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What model/brand of active crossover is anyone using? There doesn't seem to be too many options, and they all are really expensive. I'm not sure I want to spend $1,000.00 on a crossover. I have a DBX Driverack PA2 and a couple of old 2 and 3-way DBX crossovers.
My other options would be to run one passive crossover, use a 3 and 2-way in series, or run two 4-ways in mono.
Quote:
Originally Posted by robertg
Hi robertg,
May be this can help (Xilica XP4080 as ab example):
https://www.amazon.com/Xilica-XP-408.../dp/B019J5XJQI
Its S/N ration is very good, from my point of view.
Or You can try with two units: 3-way stereo that can work together so to rech 4-way stereo, such as a mentioned DBX Driverack PA2.
Using 4-way DSP driven can allow time compensation (alignment), that is not possible with analog type network.
regards
ivica
The XP-4080 would suit my needs but not my budget. I also found a Rane AC24, Ashly XR4001 and a DBX480 which are also expensive.
I was thinking of running the DBX Driverack PA2 first and splitting the lower frequencies with a two-way DBX analogue crossover. This way the Driverack would still be able to control everything. The low and mid-low would be split at approx 200 HZ by the analogue crossover, and the Driverack first crossover point would be 1200 HZ. The low and mid-low would not need any time alignment because they are cones mounted on the baffle.
A very tardy response to this thread, but something that's been on my mind lately.
The crossover, passive or active, is very close in importance to the speaker drive units themselves.
And, once one is "going active," so are the requisite measurement tools, such as the now-popular, and inexpensive, REW measurement software, a laptop, and the associated calibrated microphone.
$1000 is not an unrealistic investment for a good speaker processor such as a used dbx DriveRack 4800 or 4820 or, new, one of the Xilica models already mentioned. (There are of course other options.)
Quality drivers such as those made by JBL, Altec, Tannoy, TAD, etc. are not cheap. And we will not achieve anything like the quality of reproduction of which they are capable with second- or third-order quality crossover hardware.
I wish I could have found a used DBX 4800 or 4820 for $1.000.00 They are more like $3,000.00 CDN. Running two crossovers in series is working fine for me, however my ears don't agree with the Driverack PA2 when it does a level assist and auto EQ. I end up turning the mids down and the bottom up.
I don’t know anything about the “Driverack PA2’s” auto adjustment system, but even the very best auto calibration systems are only as good as the mic placement. Better systems average numerous measurements as no single location will every give you an accurate sonic picture, but even with numerous measurements, the locations are critical.Quote:
Originally Posted by robertg
Trust your ears and feel free to correct the “auto correction”.
Widget
Please describe your loudspeaker systemQuote:
Originally Posted by robertg
Any active crossover is a cool 😎 way to do diy
It will sound between- okay and good in a sunny day scenario.
No amount of AI is going to replace the skill and experience of a world class engineer like GT when it comes to crossover networks.
If you are following a Jbl design Biamping would be a good place to start.
The bottom end is 2-2226J up to about 300 hz, 2123H up to 1200hz, 2446 with a 2311 or a LE85 with a 2307 up to 8000 hz, and a 2405 on top. I change between the right and left horn once and a while. I'm also going to try a 2350 with a 2440 one of these days.Quote:
Originally Posted by Ian Mackenzie
I think I would get board with a passive crossover.
Robert - very nice! Are you into computer audio? If so, then I would recommend Audiolense XO as a "digital" XO that would run in a software music players convolution engine like JRiver Media Center or Roon as examples. The digital XO is linear phase and sum perfectly in the frequency and time domains. Additional to the XO, one can optionally time align the drivers, provide frequency and time domain (i.e. excess phase) correction.
I wrote a few articles on it here and here. I upgraded the subs that went with my JBL 4722 and one can see the frequency and time domain correction here. Audiolense would have no problem with a 4 way system.
All the best,
Mitch
Hello,Quote:
Originally Posted by robertg
First I am not a pro. After years with an analog EQ Orban674A, afterwards I used a passive JBL 3105 for the high in combination of the EQ. so I looked for a more versatile DSP for my 4-way project, I played with a pair of EV DX-38, I liked it but I was lucky to be offered a used XTA DP448 to an affordable price, I like it, believe me the sound quality is satisfactory. In my research I also looked in the new and the Xilica seemed to me the best choice of the moment.
Hi robertg,Quote:
Originally Posted by robertg
Very, very interesting solution, i have not seen such yet. As You have said, You can exchange 2446&2311&2398 with 2420&2307&2308.
Any of the combos operates from 1200Hz to 8000Hz. What is Your experience. Any differences ????
Regards
ivica
The 1" horn has an aluminum radian diaphragm, and a metal McCauley 416 lens. The 2" is the original titanium diaphragm with a replica 2308 lens. To be honest, I don't hear that much of a difference. I like the 2" horn slightly better, but I can't say why.
I'm going to change over to a McIntosh 7108 multi channel amp to run the top and probably just use one RAMSA WP9440 on the bottom. Using two is overkill. I walked outside when it was playing at a moderate level, and I can't believe how much everything on the outside of my house vibrates. That can't be good for the house.
I don't know if this is any help but I run 4 way active with a Marchand XM44 3 way crossover, the Crown class D on the bass has its own crossover.Quote:
Originally Posted by robertg
With the DAC having such a large influence on the sound I find I am getting some nice sounds out of my system.
I never knew an amp like that was available. What model of Crown is it?Quote:
Originally Posted by David Ketley
Its a Crown XLS 2500 not an expensive amplifier but it controls the JBL 2245s far better than my Musical Fidelity KW 500 did.Quote:
Originally Posted by robertg
Another revelation one of my Yamaha M60s went faulty so in desperation I hooked up an old Denon RCD M37DAB unit, class D I think, onto the Beyma slot tweeters, 105 db and was very surprised at the clarity of the top end! Maybe I've got cloth ears and no testing equipment but I wonder if one really needs to spend vast amounts on high powered amplifiers when you are driving speakers Actively that are highly efficient?
If you’re up to a swim in the deep end of the pool you can buy a used BSS160 well within your budget.
Imagineering really applies when you’re deep into these things with programmable logic objects and all the other tools available as drag, drop and virtual wiring.
There is a real learning curve as with anything this open and powerful.
Barry.
Your direction or progression depends on "what" or the "reasons" for thinking about going active.
Are you just playing around for fun or looking to improve it.
If you are playing around then by all means go full active with anything you like because unless you have a bunch of expertise in the programming and a DSP system and experience in the theory and practical aspect of measurements its a very long road to audio nirvana and a short road to hell.
If you want a better sound go passive with the 2123H - Horn - 2405 using the 3155 equivalent crossover charge coupled you will be out of the blocks closer to a JBL designed and voiced system straight off.
Simply bi-amp the woofers to the 2123H with an analogue Bryston 10B or something of similar quality. Use the Mac on the mid, horn and slot and you are done. Game over.
DSP time alignment will only give you a time aligned response at one 3D point in the room.
Yes that's fact. Ask Wilson loudspeaker owners who have paid a fortune for a time aligned SOA loudspeaker.
One JBL engineer told be me the DSP crossovers used by JBL are rubbish in the context of SOA digital system required for a hi end home system. Yes that's what he said.
So go figure.
I started this thread over a year ago when I built these speakers. Using a three way and a two way active crossover in series is working fine, but I’m always looking to change things. I might try making a passive crossover later in the year when Winter arrives, however I don’t have the time now.
I was under the impression that an active crossover sounds better?
Have you considered using a DSP based crossover? I’ve used miniDSP products in the past with great success? DSP is the ultimate tool to voice your system according to your liking.
The problem with DSP is the DACs. A Dac has a major influence on the sound.Quote:
Originally Posted by Champster
My ideal system would be DSP outputting in 4 channels digital to four dacs using Stereo Coffee Lightspeed attenuators for master and channel volume controls.
Having Limited funds I find A Marchand XM44 and a Lampizator DAC with a Stereo Coffee Lightspeed attenuator as the master volume control gives me what I want. No Eq. I had the system tested and it threw up some problems I adjusted some speaker parameters to fix them eliminating Eq.
I just keep it simple.
I was under the impression that a DBX Driverack PA2 was a DSP?Quote:
Originally Posted by Champster
It certainly is. :)Quote:
Originally Posted by robertg
Barry.
You have to appreciate we get a number of members post threads like this.Quote:
Originally Posted by robertg
The difficulty is without context of an actual conversation with you or a visit to fully understand your situation any response can only be general. Every diy Audio person is after a better sound but what is better? I don’t under what better is without clearly defining what aspects of the sound you like and dislike at home? What anyone hears from their audio system is an illusion of the recorded event. Your likes, dislikes and sensitivities about the illusion you hear from your system are unique to you.
As an example say l visit your home. You sit me down to hear your system and ask me what do l think about the sound? I will only be able to relate that sound to my illusion. I might own the similar system or something very different but my likes, dislikes and sensitives are going to be different to yours. So you are going to get a variety of different responses.
Btw what analogue crossover are you using? The DBX?
If your are adventurous you might try and borrow from an audio buddy a large Jbl 2397 Smith horn or Tad style horn and place it on top using the 2446 drivers. Why? Because typically this is what people do with these large systems.
I know one guy who did this for a while and then changed to a large multi way horn system.
After the DBX Driverack I am using an analogue ART CX310 to split the 2226 and 2123 at 300 hz or so. I had a DBX 223 also but one channel didn't work. The ART was really cheap.Quote:
Originally Posted by Ian Mackenzie
I tried a pair of 2350 horns with 2440 drivers for a week of so, and now I'm using a pair of 2345 horns with 2470 drivers. Each one sounds slightly different, however I can't say which I like better. They both don't really cut it in the looks department. Hopefully I will find a pair of 2397 horns to try.
You could stay fully analog.
- The DBX 234 is a very good filter, but not so exact regarding frequencies. You will need a 223 to get 4 way.
- The BSS FDS 360 has a good reputation. You need 2.
- Klark Teknik DN 800.
The BSS and Klark needs soldering to change frequencies.
You will also need an EQ. Primarily to get baffle step sorted, but it is also handy if the drivers or boxes are not linear. Good EQs:
- DBX
- Klark Teknik
- BSS
Mårten
I liked the 2309 horn with lens 2310.
Make shure the horns doesn't ring. Very simple to test by knocking them. The ringing will affect the sound a lot.
/M
The 2446 diaphragm being Ti generally could use a little magic dust , some of the chaps here may still have some. Works a charm.
Ian you got any , or Rich ?
I changed out my speakers but they are still a 4-way, the upper mid is now a 2440 with a 2311 horn, and the bottom is a single 2245.The cabinets are 4345 clones.
I tried a Crown XLS2502 on the bottom end, it has a built in crossover so I just used it with the DBX Driverack. My preamp has two outputs, so one went to the Driverack, and the other went to the Crown. It worked well, but I couldn't stand looking at the Crown, so dam homely looking. I still think a good amp should weigh at least 60 lb also. I'm back now with the bottom end of the Driverack split up with a DBX 223XL. I'll probably leave it like that for a while.
I also tried a Fostex H425 horn and a D252 1" driver in place of the 2440.2311 combo. I thought it sounded slightly better. When I finish restoring the horn I will try it again.
It's the old school way of thinking here. I'm not running my stuff in the living room so my thoughts are probably different.Quote:
Originally Posted by robertg
I got a couple of the newer crown XTI and CDI amps. The programming is easy and there's a lot of stuff built in. They don't weigh much and they put out a lot of power. I don't know the technical side fully, or at what price that power comes?
I'll find out just how much they draw. I love the built in stuff so far. I have to be honest that it scared me at first to trust it fully. I always used separate stuff for all this control.
I still have a set of LN Crown Micro tech 1200s here and will keep them for back up and/or monitor use. Seems like a XTI or CDI 1000 does just as much if not more at a fraction (1/2?) of the weight. I also got a QSI amp before realizing that there's no real DSP control inside on that model. It is also light weight and puts out more than the smaller Crown's do.
Again probably of no concern for sound systems that don't move.
Has anyone had any experience with a Ashly Protea Digital Speaker Processor?
What is your impression of it's sound quality?
And how does it compare with other Digital Speaker Processors out there?
I am currently using a Ashly XR4001 crossover and I am thinking switching to a Ashly Protea 4.8SP DSP 4 in & 8 out Digital Speaker Processor.
And I am wondering if it would be an upgrade or not?
My current system does use some passive EQ networks between the amps and the 2012 and 2446 drivers to get a fairly flat frequency response.
I am thinking that with a Digital Speaker Processor and my CLIO speaker testing software that I might be able to dial it in a lot better.
So, any advice would be helpful.
Baron030:)
I think I saw where Widget was using one, but on the woofer only. Found it.
http://www.audioheritage.org/vbullet...l=1#post424651
I have one and have played around with it (3.6), but didn't really try to compare to anything else. It's easy to use.
Yes, I am using it as a simple DSP and only on my Sub1500s... it is quite invisible in this application. I haven't limited its functionality in my system due to extensive listening tests and felt it wasn't up to snuff full range, I simply have no need for it beyond the application I am using it in.
I suggest you try it out and let us know what you think.
Widget
Not many posts here in recent times.
Just wondering if anyone wants to share their active crossover experiences?
I have acquired propensities for long wordy posts so l will try and break up my recent experiences in single posts.
To my unnecessarily structured way of thinking an active crossover is not necessarily the go to solution for musical enjoyment or your next loudspeaker project.
An active crossover is not like a preamp or a source component.
The basics cannot be assumed or overlooked.
1. It’s a processor in that it divides the audio spectrum into bands that are delivered to specific individual loudspeaker drivers. Sometimes the crossover makes an approximation or a different crossover characteristic. Or your just guessing what’s required. The bearing on the significance of this requires investigation.
2. The user needs a degree of understanding and familiarity with the said loudspeaker drivers, crossover network principles and how the said active crossover can be programmed or set up.
That’s often a void of unknown limitations towards the success of an effective active crossover in a system.
3. What goes in one end of the active crossover and out the other end is not entirely to be assumed a straight wire with unity gain. Stereophile Speak. Just like any preamp. There’s differences is performance that are next put into context of your existing audio components.
4. User error and false assumptions plays an influence in the psycho acoustics of what is perceived in the absence of proper measurements. For example some Pass labs XVR1 users l met in HK were adjusting the slopes and the Q of the low pass filters and making assessments on the performance of the drivers in an Everest DD67000. Their impression was the woofer diaphragm was too slow. It was simply louder than the horn. It try telling that to the hifi nerd. What they weren’t aware of is that these adjustments increased the Gain of the low pass filter outputs. This lead to incorrect observations. So users can get lost in quest which on the face of it is ideally perfection.
So in summary it can work very well but is best done in a controlled way. That generally means simpling the user interactions with the active crossovers.
Where to from here?
Again applying more structured thinking the application of an active crossover can be classified into some applications. This then enables a more specific focus on the active crossover design and user interactions. Nelson Pass and myself spent a long time discussing the active crossover needs of various end users and we came up with two basic categories outside of Pro Sound applications. Greg Timbers was instrumental in providing technical insights to determine the precise requirements for JBL systems.
1. Pre determined loudspeaker system. The plug in and go customer.
The premise of this application is the loudspeaker has been previously designed and or built. The loudspeaker has built in active crossover capabilities and known active crossover settings. The active crossover can be thus implemented with program preset crossover settings with limited user requirements for system set up. The setup can get further defined of a limited range of level settings.
2. The project/diy louder system. The thinking cap customer.
This application is more open ended in that the user has license for prescribing the loudspeaker system design meaning the component choices, enclosure
requirements and owns the design of the crossover characteristics and system set up.
Classification of the JBL driver range and horns can be used to define the frequency bandwidth of each filter and deliver guidance to the user. This simplifies the selection of crossover filters requirements.
A selection chart can be drawn up much like in JBL enclosure kit to provide compatible loudspeakers drivers, horns and appropriate crossover characteristics.
Subject to further investigation the existing pre determined systems can be improved with active crossover approaches not available in passive crossover implications. This was applied to the JBLDD67000 where the helper woofer was actively driven by a dedicated power amplifier in a Tri amp arrangement. The active crossover filter arrangement was entirely different to the passive configuration. The results were a significant improvement over the stock bi amp mode and stock passive mode of operation. Greg Timbers originally designed the DD67000 as a Tri amp system but Harman limited the market offering to passive and bi amp. Much of this is about the skill of the loudspeaker designer.
Improvements can be applied to other JBL systems including the legacy 43XX systems which go beyond what is possible with passive crossover implementations.
If your following these posts the structured approach to the application of active crossover very much makes the application of the active crossover easier implement successful. Take out the guest work, the unknown unknowns and assumptions and success is well within reach of the consumer or novice.
Looking at the hardware choices the pre determined loudspeaker systems can be catered for with crossover cards much like the JBL5234/5235 and the JBL DX1. None of these units are now in production. The post author is currently engaged in a pre determined active crossover design which will be manufactured in limited quantities. A thinking cap customer version is also being designed.
Looking at other options there are not many of any commercially available active crossovers specific pre set crossover characteristics for pre determined loudspeaker systems. JBL have the M2 covered via the Crown amplifier range only.
The limitation of all universal active crossovers including dsp digital and FIR digital crossovers is as stated above. You have to know the precise crossover settings and a detailed understanding of how to program the active crossover. There are no guarantees your crossover or you are going to get it right. Unless you have a lot of time and patience and so does your spouse the novelty can wear thin as the days, weeks and months and potentially years pass while you explore numerous adjustments. Not to mention test equipment. This can be like navigating a life boat through the solar system with only stars as your guide.
Some consumer loudspeaker manufacturers such as Dynaudio and Kef are spearheading full active loudspeakers. An active loudspeaker as a rule has all the power amplifiers built inside the loudspeaker.
It’s keeps the loudspeaker cables from cluttering your room and looks tidy. But you have to give up your choice of power amplifier.
The success of these systems is varied based on my own assessment but they are getting better.
The inherent limitation of these systems is the 61/2 drivers used cannot project the same output of a floor standing JBL system without distortion. Such small drivers are low in efficiency and they waste power through heat. This results in power compression.
Looking more closely at post 34/35 above in more detail.Quote:
Originally Posted by Ian Mackenzie
One of the misconstrued notions about a digital universal active crossover or any universal active crossover is that its quick easy fix to diy loudspeaker projects.
The novice is lad to believe he can quickly dial in the crossover for a flat response and I am done. Unfortunately thats not how it goes.
Unless the user has detailed understanding of the compression driver and correct loading of the horn in use a satisfactory result beyond PA sound is unlikely.
The best place to start is the closest passive crossover recommended from JBL or JBL designed system and simulate the passive crossover in SPICE.
This analysis will provide valuable insights into an appropriate voltage drive for that driver and horn combination.
If you are unfamiliar or don't have the skills to use this analysis you are far better off considering a pre determined loudspeaker design. JBL aren't stupid and they hold the key for diy active crossover users in their passive crossovers.
The crossover options in a universal active crossover are really only appropriate for a theoretically perfect driver. That doesn't exist in practice. A typically horn and driver will start to reduce output at the lower edge of its lower pass band at 6-12 db per octave. Using a LR 24 db crossover will not provide the correct phase response in the crossover region because of the phase response of the horn and driver. The user will need to assess different crossover slopes and different crossover frequencies until a measured uniform 24 db acoustic slope is obtained. The level of practical skill and experience required is not a cake walk and is beyond most amateur loudspeaker builders. The optional vertical polar lobe response of a LR 24 db crossover is only obtainable with a phase alignment of the drivers at the crossover point os optimal. This must be measured and then an all pass filter applied to the low or high pass crossover output.
If this exercise is done with your ears or you rely an flat response from your simple RTA it will not be a satisfactory result. Psycho acoustics will lead you down an endless rabbit hole long after the sun turns into a Black Hole. With some white board exercises and practical tutorials a novice can grasp the necessary principles and the process of obtaining an optional crossover. I plan to trial a webinar on this topic for interested diy loudspeaker builders. For those invested in obtaining a result as good or better than a commercial system a kick starter course on this topic is a must.
Such a course might run for 6-10 weekly instalments and cover.
Basic loudspeaker principles
Loudspeaker measurement techniques
Crossover design basics.
Loudspeaker system design basics
A practical tutorial sessions covering
1. System driver selection
2. Use of REW free measurement system with a calibrated mic
3. Loudspeaker driver measurement on a baffle
4. How to interpret loudspeaker measurements, amplitude, impedance, phase, distortion
5. Acoustic crossover response measurements, amplitude and voltage drives
6. Techniques for optimisation of crossover frequencies, phase transform, amplitude
In a webinar attendees can ask live questions, share experiences and make a contribution to the discussion. This format of workshop is run at some catch ups in the diy audio scene and people get a lot put of it. If this interest you let me know.
To answer the previous, years old question I've been using an Ashly Protea 4.24D DSP as my living room stereo crossover for several years. It's software is easy to navigate and its feature set is ideal with the only real shortcoming being a lack of FIR filters. Not something that I've missed for my applications. I still prefer the sound of the venerable BSS FDS366 but I had a dozen of the Ashlys so inventory won out. The fan on the BSS also needs more remediation if used in a home setting. Both are gained staged for use with +4dbm levels so also need some gain staging attention when used with -10 hifi amps.
In my experience DSP crossovers yield far better results than passive networks or analog electronic crossovers but then I have decades of training and experience in acoustic measurement and plenty of tools for measurement making. If you don't have those elements then it'll be an adventure and a potential disaster along the way but with a few exceptions it affords much greater chances for better sound.
Quote:
Originally Posted by Ian Mackenzie
Great 👍 post.
Your point on the fan is noteworthy.
A while back a number of users of BSS units hit this fan noise problem and attempted various diy adventures to mitigate the noise. The same with some Crown power amps recommended for the M2.
In a domestic situation what route you decide on is going to be a compromise in one way or another.
If you goal is better sound then consider what that means to you and your budget. In the hifi genre side of the hobby as opposed to thrift or eBay purchases you generally get what you paid for.
In my experience with the DD67000’s those users had the means to buy anything and they went analogue with Pass XVR1 universal crossover. But those crossovers are by no means straight forward to set up. They are sonically great once set up using measurements but not the last word in transparency according to Greg Timbers who made his own modifications including bypassing a number of electrolytic coupling capacitors in the signal path. Pass to this day refutes electrolytic coupling capacitors are an issue and points to active gain devices. Pass stopped manufacturing the XVR1 a while ago.
On the fan noise it really is a pain if you run your system a normal domestic levels.
The quietest fans are around 30-40 db or so. But around 60db is going to annoy you after a while. To explain the drone of a fan masks the resolution of your expensive beryllium drivers. A lot of people want accuracy, a clean sound and so on but they underestimate the significance of noise impacting on those goals. If the noise floor of your system is not sufficiently low enough the noise will ride on top of the low distortion levels and the lowest level clean signals and your back to square one.
A simple way to assess your system noise floor is to pause your source with the preamp volume at your normal listening level. Then carefully listen to the level of apparent background noise. This could include faint but perceivable mechanical or electrical buzz, your refrigerator, a sound like ocean surf or a hiss. When you un pause the source it’s noise floor will also intrude.
One solution is to put your equipment in an adjacent room.
One of the bug bears with using an active crossover is the issue of ground loops that can intrude as a hum or buzz. In most but not all cases this is mitigated with balanced equipment inputs and outputs.
However, the balanced system relies on the absolute cancellation of the common mode noise signal on the differential signal. This is very much determined by the absolute impedance balancing of your balanced output of your equipment and balanced inputs. A mismatch of 1% can have serious detrimental effects on the effectiveness of balanced connections.
Secondly, balanced equipment inputs are in face much noisier than unbalanced inputs. A balanced input typically has a signal to noise ratio of -104 db. An unbalanced input is typically -117 db. This has to do with a trade off between common mode noise rejection which requires high impedances to work and the inherent noise of a high impedance circuits. The noise performance can be significantly improved but it’s more expensive to design and manufacture so most equipment manufacturers not bother to tell you this.
As a rule the noise level should be at least 70 db below the lowest signal level in normal operation. Not the manufacturers rated noise performance at the rated output. The reason is that in practice your signal from your preamp could be -52 db below the rated output of your 200 watt Macintosh power amplifier.
To prove this where the power amp has a balanced voltage gain of 23 db and a rated output voltage of 40 volts for 200 watts rms into 8 ohms, the input voltage required the rated output is 2.83 volts from your active crossover and your preamp.
But for a mere 0.1 volt output into your loudspeakers which is quite audible the input signal to your power amp from your active crossover is -52 db below the 2.83 volt input level for the rated output of 200 watts. If your noise floor is at or around this level then your dynamic range is 52 db which is not really acceptable. As l mentioned above your noise floor should be way below the threshold of audibility. That threshold might be another -20 below that 0.1 volts of noise at your loudspeaker terminals. That’s -72 db below the 2.83 volts input for the rated output of the power amplifier. The power amps noise level might be -110db.
After starting this post I did end up buying an Xilica XP-4080. I ended up parting out these speakers and building a pair of 4345 clones. I used the Xilica with the 4345s for a bit, but running four amplifiers was a real pain. I then built a passive crossover for the 4345s and used a 2-way Bryston 10BLR.Quote:
Originally Posted by Ian Mackenzie
My current set-up is a pair of M2 clones with a Crown DCI 4x2400N. I got rid of my pre-amp and DAC and just use a BSS BLU-USB connected to my amp with a Cat 6 cable, nice and simple. My Mac keyboard is the volume control and I have a Furman RS-2 remote control panel and MP-30 to turn on and off the amp. The amp is in my basement right below the speakers. It had really loud fans so I had to move it to a different space.
To sum it up I would never do a four way active system again.
The story does not end there.
If your crossover has a rated noise level of -110 db then it’s connected to your power amp with a rated noise of -110db the noise level jumps to -104db. How do? The residual noise level of the crossover and the power amp sum together or double. This is a +6db level increase. If your crossover has a noise level of -104db the crossover will be the limiting factor. In practice this noise level is only -32 db below the example above. When your turn your preamp right down to just audible it’s around -35 on the volume scale.
With these relatively sensitive JBL systems that sensitivity is your friend for those dynamic peaks but your foe with that residual noise floor.
So how do l reduce my noise floor?
As equipment designers we look to what is referred to as low impedance design. In audio circuits there are a number of noise sources. Johnson noise is the noise generated by resistance values in the circuits. To reduce the noise by 10 db we need to bring these circuit resistance value down to 1000 ohms or lower. However the monolith Opamps used in this kind of equipment begin to loose linearity and the distortion level rises rapidly.
Another problem arises. The monolithic op amp only has a small fraction of output current in class A. It therefore has to drive this load in class B. But class B leads to higher distortion and noise of the circuits power supply.
The brute force way around this problem is to use parallel monolithic opamps which is a practice in some mixing desks. The more elegant and superior solution is to employ a discrete operational amplifier. A discrete op amp can drive a 75 ohm load is some cases all day every day. The trade off is cost and power consumption. Your power supply will need to be re designed and upgraded. So the overall manufacturing cost goes up and you have to pay a more.
What this comes down to is don’t skimp on your active crossover. It kind of defeats the purpose of the exercise overall. Particularly if you have a high or premium grade of other audio equipment.
Digital is one path but take Riley Casey’s comments into consideration.
My analogue crossover l have mentioned will use discrete operational amplifiers and low impedance design. The estimated cost ex works will be around US$2400 mark. In adjusted US$ the JBL DX1 would be US$2110 today. This thing will cover the pre determined loudspeaker category and diy / project users with a suitable measurement kit. I will be looking to obtain a BSS OmiDrive or evaluation. I think it’s a case of being aware of developments in this area as it is the gate way to your end result.
Getting something really good and knowing how to use it properly can in fact mean a much shorter journey in terms swapping and changing out horns and drivers. This is because your finding out first time around what’s really what. You definitely don’t want to be stuffing around too long because it will become wearing and ultimately frustrating.
I have seen some people upgrade the legacy JBL 5234/5235 active crossover with new monolithic opamps in the past.
This is a good idea where the Opamp used was a TL074. This Opamp and is dual package TL072 have a much inferior common mode distortion performance when used in Sallen Key active filters (1) (2).
Unfortunately there are relatively few good audio opamps in a quad version without looking at a SMT package. Texas Instruments now manufacturer superior monolithic opamps if their marketing can be believed. However, not many of their Soundplus range of opamps are only specified for their rated performance in 2k ohm loads. All of these op amps rely on complex distortion cancellation circuits to produce low distortion in class B operation. We can’t see these cancellation systems because Texas Instruments do not disclose the Opamp schematics.
Class B operation is used because of its efficiency. Because everything in a monolithic Opamp is contained on a tiny silicon substrate problems associated with heat and temperature must be avoided.
(1) Douglas Self . The Design of Active Crossovers.
(2) John Caldwell . Distortion and source impedance in Jfet opamps
https://www.ti.com/lit/an/slyt595/sl...-df-pf-null-eu
In the previous post l discussed some of the performance limitations of monolithic opamps in audio applications.
But this is not really new news. Dean Jensen, an astute and very talented American audio engineer realised the limitations of monolithic opamps in the sound recording and motion picture industry back in the 1970’s. What he did off his own bat was thoroughly research the subject of operational amplifiers and then designed a discrete operational amplifier and patented the design. Jensen then made the patent public. The Jensen 990 discrete op amp became the industry standard. All discrete operational amplifiers used in professional recording microphones are based on the original work of Dean Jensen.
Dean Jensen worked in the installation of large format studio mixing desks in the 1970’s. Jensen went on to establish Jensen transformers because he was dissatisfied with the performance of audio transformers of that era. Bill Whitlock, a close friend of Jensen refers to their technical efforts and that of many others as the sound of the 1970’s. Whitlock reasoned it was not one particular piece of equipment but the collective sum of the recording process that gave analogue recording a particularly natural sound that has been adopted as the vinyl sound today.
Today recording studios with analogue equipment are highly revered by well known artists.
So why are discrete operational amplifiers not more widely used in professional and consumer electronics. The answer they are used in premium equipment but that comes at a cost. The question then is is it justified? Only the user can answer this question. If you own a quality record collection, a quality turntable and associated audio equipment you will probably justify the cost over the mass market lower cost monolithic Opamp based equipment.
If your largely a digital based user who streams largely from a provider and has dsp based equipment you might not justify the cost.
The cost of a discrete Opamp as component starts at US$50.00 and goes up from there. In comparison a NE5532 monolithic opamp costs US$0.30. That’s a whole magnitude difference in cost and some equipment would have ten or more opamps. If you cringe at the price then think about the cost of manufacture and inventory. This is why such manufacturers are small boutique businesses. Their products that they manufacture are highly sort after by those who place value on this level of equipment.
One way of looking at is to draw an analogy with maintaining your jbl driver collection. These days you can buy a new replacement woofer for the cost of the repairs. But once it’s gone then it’s gone forever and that sound you cherished.
Riley Casey commented in another thread that some in built Eq in an active crossover can be quite useful.
Without doing a deep dive into what EQ can and can't fix as a rule EQ can't fix phase cancellations caused by room modes which cause deep narrow dips. This is also true of phase cancellation in the crossover region due to differences in path lengths in sound waves reaching the listening position.
EQ can however be useful to moderate some room induced effects in the low frequency response. These effects depend on the location of the loudspeaker and the listening position in a room.
Typically bass cut is required to reduce a peak causing boom or a broader shelf cut action where the loudspeaker is located near a floor and wall boundary. These effects can be in the order of 3-10 db. Other room effects can occur between 60-150 hertz as a series of peaks or dips where sound waves wrap around the enclosure and either cancel or add. The best approach is to use modest cut to subdue these effects. So this EQ might be presented by an LP shelf EQ and a parametric EQ. Measurements are best used to assess where the EQ is required.
Other room effects are more subtle but can influence the perceived clarity of the system. For example it is not uncommon for a room to have a resonance in the 250-340 hertz region which can mask midrange clarity. This can be dealt with using a fixed frequency low Q EQ and a switchable level of attenuation.
EQ can also be useful where the actual monitor has a broad frequency response variations both on and off axis. This can be assessed using high resolution measurements on and off axis and averaged to provide broad low Q EQ in subtle amounts of 0.5db to 2.00 db correction in defined areas. The correction can be preset on a plug in EQ card in the crossover or a user access switchable corrections in incremental amounts to their own taste. This is the power of a high quality active crossover. The key is having very accurate data from which to make these corrections. In most cases its simply a case of measuring a system in a defined environment accurately and then determining the EQ correction. This can be done with a test system. Unfortunately an accurate set of measurements is unlikely to be accomplished effectively by the user at home unless they are enthusiastic.
This is a much more tidy approach than offering the users a knob farm to fiddle with. Your time is far better spent listening to your music than messing around with EQ adjustments when your not sure what your really doing.
The legacy systems have somewhat sloppy and imprecise L PADS.
There are several ways of dealing with this to obtain a level overall tonal balance. The L pad can bypassed with precision calibrated fixed pad for the mid, horn and slot. Or the calibrated pad could have three or five switched positions. I can organise that to replace the variable L PADS. a descent Greyhill or Lorlin rotary selector switch and a small pcb with some MILLS resisters is a better way. The mid LPAD can be a fixed pad when bi amping.
Alternatively the user can conduct their own measurements using REW and trim the L PAD settings. I am inclined to view this as messy.
By adopting a structured approach all these small variables can be defined and measured. The result is a significant improvement in L+R tonal balance matching and stereo image. In my experience this kind of approach makes a surprising subjective improvements. I experienced this when Greg Timbers set up and bi amped a 4331 system at his home and we were very pleased with the results. Its s a very good loudspeaker if properly set up. So you imagine the improvements with a more sophisticated system.
.
Hello IanQuote:
EQ can also be useful where the actual monitor has a broad frequency response variations both on and off axis. This can be assessed using high resolution measurements on and off axis and averaged to provide broad low Q EQ in subtle amounts of 0.5db to 2.00 db correction in defined areas.
Just adding a little clarity. For Constant Directivity systems, think 4430 where the on and off axis response are very similar you would get the most benefit. With system using beaming horns or systems with abrupt changes in directivity think 4333, Urei 811 this will not work as well. So it's important that the user understands the ramification's of trying to "fix" the overall power response and the influence that directivity plays on the effectiveness of EQ.
This is a good read
http://www.audioheritage.org/vbullet...me-1-Number-11
Rob:)
Hi Rob,
That is exactly right.
That’s why l think offering some preset EQ options that have been thought through carefully is possibility. The measurements l or Greg would do on a test system such as in the case of the 4333 would need averaging and then related to how the user positions the system and their room acoustics. Two or possibly three different preset of EQ would be available depending of the users set up.
People tend to ask too much of EQ according to Nelson Pass. If you try to knock out a kink in the response completely it can cause other problems. What Pass found with the late Dr Linkwitz in the LX Linkwitz crossover was that the more gentle analogue EQ compared to the abrupt DSP EQ was indistinguishable in carefully listening by Dr Linkwitz. The consensus was the analogue was subjectively better compared to the mini dsp. That’s really interesting. Dr Linkwitz was a very fussy and a very smart guy so it just goes to show what can be done when it’s done carefully and correctly.
It’s a space that needs a thorough examination or trials by users for feedback
I have measured some polar responses of the 43XX system and they track not bad over defined arch. But of course toe in has an impact. JBLs suggestion of a 5-10 degree toe is in fact because the 4344-45 measurements are smoother with small toe in and you get less differential reflections off the walls. They know their designs well. LF problems in rooms is where EQ can make obvious clean up.
Used sparingly to solve specific issues EQ is a useful tool in your tool box.
An extension of classic analogue EQ in the studio recording process is the selective addition of tonal colour. This is done using various techniques which exhibit saturation. The effect is what Neve call silk in their high end equipment. API and other legendary studio equipment manufacturers have this genre of analogue equipment used by major studios. The intention is to make an otherwise lifeless digital stream more natural. In the past some consumer CD players used broad bush tube buffers. The effect is more selective and precise in analogue EQ.The audiophile does this by trading in and out various brands of equipment until they feel comfortable with the subjective sound. There is therefore application of analogue EQ for the digital streamed program source.
When the weather here clears l will post some driver and system measurements with and with out EQ for illuminative purposes.
Another application of structured design is to provide precise EQ for different compression driver diaphragms, alternative drivers, horns and wave guides.
This give the adventurous Thinking Cap Customer the opportunity to explore with confidence the subjective qualities of alternatives. People who enjoy high fidelity sound reproduction are generally curious individuals. The above pre determined EQ gives this interest group the opportunity to efficiently sculpt their own sound. Offering the ultimate frontier. But done right the first time “in a systematic and controlled manner”. That’s a phrase straight out of a JBL brochure.
The implementation of these approaches can be arranged by plugging in a card specific to the users drivers and system in use. The thinking’s been done. A small amount of user engagement might be offered for fine adjustments within a defined range. A 0.75db change in sound level is generally accepted as the perceived difference in sound level. (1). Wow l did that and l like it better! But the subjective effect of such small measured differences can have a noticeable effect on tonal balance with low Q equalisation.
(1) Douglas Self. On psycho acoustics and subjectivism.
I'm using a JBL DSC280 in my main setup.
Works very well for my needs
My main setup uses a 5 way left and right. Every driver is on it's own amp. 13 channels of amps running it all including my 3 way center channel. No buzz or hum at all. Very quiet.
Everything time aligned thru the crossover.
I really want a room corrector for that system.
Do you not have enough EQ on the input side of the DSC260 to do your "room correction" ? In my experience room correction is done with a sledge hammer but I think I understand what you mean.
Quote:
Originally Posted by jblguy
Yes I do use the DSC 280 for time alignment. As well as crossover too. But I don't add any EQ at all. All driver are run flat and set at equal volumes.
That's why I always felt the final tweek would be to add the corrector to fix my fuck ups. plus it can fix any rooms issues.
I have the Mcintosh MEM220 on one system I have and it really sounds goods. But that room is an odd shape so it needed the correction for sure. It's running a Paragon which could use some help anyway. so pretty good all over that room for sure.
We’re all cloth eared at this late stage…Lol
I have always wanted to play with one. The Lyngdorf Room Perfect system that is the heart of the MEN220 is great at integrating subwoofers into a system and can eliminate low frequency room problems. I am very familiar with Room Perfect. I have it in my Lyngdorf processor in my home theater and use the Lyngdorf processors in customer’s systems regularly.Quote:
Originally Posted by jblguy
Are you bi-amping the Paragon or using the lower outputs for subs?
Widget
THe Paragon is all on the original spec crossovers from JBL. I just forget each crossover number. But the same unit s JBL used. I do cheat a bit and use a 15 inch separately powered sub as well for this. The paragon doesn't go very low. We use for TV and movie sound too. so needed some kinda sub. The sub has it's own plate amp for it's power. I do use a Paradigm volume and phaze shift box on the sub. With cutoff dial as well. X30 model. Gives some nice control over the sub.Quote:
Originally Posted by Mr. Widget
Attachment 90661
The odd part is you kinda set and forget the room corrector of course. Once setup unless you move stuff around or change the room somehow it doesn't rely need tampered with again. Yes I love the thing. Stupid money though.Quote:
Originally Posted by Mr. Widget
IMO it's the icing on the cake for any serious system and you really don't know if you have it right with out one. Ya can think you do....but it knows better.....smart little thing it is . Way better at telling than me.
If I had a Paragon I would probably add a subwoofer too.Quote:
Originally Posted by jblguy
I’m confused about your setup though. Are you using a self powered subwoofer with the Paradigm X30 and the McIntosh MEN220?
Widget
Yes that's correct Mr Widget.Quote:
Originally Posted by Mr. Widget
Hmmm... seems pretty unusual.Quote:
Originally Posted by jblguy
Widget
My mistake no X30 in system. It's coming from the sub output of the MEM to the input of the sub the way it should be.Quote:
Originally Posted by Mr. Widget
Just getting back to comment on your post.Quote:
Originally Posted by robertg
Was it the inconvenience, complexity or difficulty with dialling in the rests with the four way set up?
Ian
It wasn't that difficult to set up, I think I had it sounding good. I just thought it wasn't worth the effort to turn on seven devices to listen for music for 30 minutes.Quote:
Originally Posted by Ian Mackenzie
I got back in to audio about six years and the novelty of having a complex system is wearing off. I'm trying to simplify my life in general.
That's too funny. Sounds like my life. With the thirteen channels of amps I have you need a weekend to get it turned on. Too funny.Quote:
Originally Posted by robertg
Gotta love Mcintosh's little power cable system to turn on everything at once. I don't have that on my mains setup though. As I've only got one Mcintosh unit there.
Actually I have most of them on a few power conditioners so it's a one button power up for most of the amps. But yes, after adding in the preamp and whatever else I need to turn on I need a nap.
Luckily it's all dead quiet. The cables I've got is rather a lot. No noise though. Whew! It took me about 5 weeks to build it all and wire it. Endless trip back to my local pro-music shop for cables. I tried to buy the best ones I could afford. Seems to have worked out.
I think it depends if you like to tinker and play.
I personally can’t live without at least bi amping for that rocket fuelled visceral impact. A full passive system is the ultimate in simplicity but it’s like driving an underpowered Toyota Prado diesel towing a van into a headwind. 135 kw is no fun 🤩. In comparison my Nissan Patrol’s 300 kw HP 98 octane fire breathing direct injected 5.7L V8 with full time 4WD you experience everything happening instantaneously. No lag, no waiting to get past that shit box in front of you!
I might put the digital plate woofer amp on the rear panel of my wonderful but ancient 4345 clones.
That way l don’t need all those egg cup holders to keep the speaker cables off the floor…..Lol. Everything matters with Audio….Lol
Please tell me Ian that you DON"T leave your speaker cables to touch the floor....eeeekkkk. :eek::eek::eek::eek:Quote:
Originally Posted by Ian Mackenzie
Are you mad man? :spchless::spchless::spchless:
Don't you know that's how Government Demons can infiltrate your copper and contaminate you cable ends. I heard of one guy who left cables on the floor and ended up eating at Arby's. You really want that Ian? For you and you family. Even your Grand kids will mock you and disown Gumpa
I suggest without any further hesitation you do what I do.
Nail them to the ceiling with 6 inch timber spikes. Right threw em nice and clean like.
Now there you go....go and get a baconator now. Demon free too.
If there's 2 things I know ( and that's about it ) it's cables and fast food.