Im about to bi amp my K2 S9800. The manual says 800 hz, but wich type of filter is to prefer? I use a DBX driverack PA2.
Im about to bi amp my K2 S9800. The manual says 800 hz, but wich type of filter is to prefer? I use a DBX driverack PA2.
Hooked it up yesterday. I use MC 1,2kw for the 1500AL and MC275 for the HF-section. A DBX driverack PA2 at 800Hz 24db/oct LR.
No equalization.
Im not satisfied with the sound. The image is smaller and has less depth than before, lots of details are gone...
I know that equalization would be needed i the driverack, but it sounds to me that the tonal balance isnt "way out"... but the imaging and resolution are.
Is the driverack not competent enough for this type of critical listening?
From Sweden so kinda hard to explain...hope youll understand.
Hi,Originally Posted by Heliac
Assuming that you switched the existing passive crossover to "BiAmp" from "Passive" ( accomplished on the hidden 2-way switch found behind a removeable plate ) and also removed the strapping connecting the Bass and HF sections >> then yes, ( trust your ears ) and conclude that the DriveRack PA2 isn't sonically up to the task.
- Smaller/Tighter images , with less depth of field are definitely moving in the wrong direction.
Did you try "Passive" type Biamping ( using 2 amps that are each fed full-range signal that are then connected independently to the LF + HF inputs > once the connecting straps are removed ) ??
Read the S9800 User Manual for a How-To" reminder.
Hello, yes i i did change the switch to bi-amp.
Havent tried the ”passive” bi-amp method yet. It could also be the MC275 that lacks of detail but im more suspicious to the driverack..
You need to match the voltage drives and understand exactly what needs to be done to bi-amp them. They use an 18dB electrical on the Woofer and a 6dB electrical on the horn 2435Be. Look at the schematics and voltage drives posted in the referenced links. Going generic will never get it right. If you don't understand how to do the conversion to match the voltage drives best to leave them be in passive mode.
When you switch to bi-amp mode you shunt/short out the 12uF capacitor. There are no other series capacitors so there is no DC protection for the 2435Be. This can be very risky. Normally when you bi-amp or go active with compression drivers you put a large value series capacitor to keep any DC out of the driver so it does not get damaged if there is an issue with the amp.
The 435Be may not be available if you need replacement. At the very least you should seriously consider adding a high value series capacitor just in case.
Rob
http://www.audioheritage.org/vbullet...10639-K2-S9800
https://usermanual.wiki/JBL/JBL5235manual.1031736606 Page 16/17
Last edited by Robh3606; 02-12-2022 at 08:57 PM.
"I could be arguing in my spare time"
With the caveats mentioned to protect your horn driver this is what you may wish to try.
I suggest you use a non polarised capacitor per the JBL 5235 manual for protection from pops or low frequencies. Go larger x 2 or 3 times as otherwise this will interfere with the crossover function on the horn. You can use a non polarised electrolytic crossover (60uF or thereabouts) capacitor 50-100 volt rating bypassed by a 0.1uf 250 volt rating polypropylene capacitor.
Going into the menu do not engage any of the PA functions such as limiter or compressor.
Go to the menu for the crossover filter type (refer to the manual or you will go crazy) and select Butter-worth 18 db slope for the woofer amplifier Frequency 800 hertz. Select Butter-worth 800 hertz 6 db slope for the high frequency amplifier.
Using the mic and analyser (refer to manual) measure the loudspeaker at 1 metre on axis with the horn.
Then refer to the tech sheet link posted by Robert H and look at the acoustic crossover response of the woofer.
Look in particular at the scale and the slope the woofer curve.By adjusting the crossover frequency either up or down in increments of 25 hertz you should get reasonably close to the tech sheet acoustic crossover curve of the woofer.
Do the same with the high pass crossover filter looking at the acoustic crossover curve for the horn.
Then combining both filters again measure the overall loudspeaker response. It should be a smooth response in the crossover region. The vertical mic position will impact on this measurement an you might try several measurements at different height levels in front of the horn.
As a test of the correct crossover setting you can reverse the polarity of the high frequency amplifier speaker leads to the loudspeaker. Then measure the system response again at 1 metre. What you should see is a uniform null or notch in the crossover region of 15-20 db.
If you see this notch you are close to the original passive crossover characteristics.
You can fine tune the crossover frequency of both the woofer and the horn slightly to obtain the most uniform and deep notch. The put the speaker leads back in the correct phase.
As a further step you can also make fine adjustments to the frequency response below 300 hertz. This is to compensate or the woofer operating directly from the power amplifier. You may find you need add a low frequency shelf filter below 100 hertz of 2-4 db boost. You may also find that a low Q PEQ filter at 290 hertz of -1 tp-2 db improves the mid range clarity as this is often a problem frequency in domestic listening rooms.
DO NOT attempt to use further equalisation offered by the active crossover. Use the adjustments on the loudspeaker only.
This will take you a whole Saturday afternoon and you ae best to do it without interruptions. Send the wife or girl friend out shopping.
I take no responsibility for any accidents that may occur. I suggest you keep the volume settings at a low level and follow all the guidelines in the DBX PA2 manual.
You might find you prefer some subjective aspects of the bi amp mode of operation but not necessarily other aspects. This is a multi faceted problem. The human mind/ear takes time to adjust and you need to be patient and re learn the subjective changes. The S9800 was optimised for the passive crossover. When you bi amp it does have a real effect on the bass. This is because the woofer is influenced by the passive crossover losses and this has a subtle but audible effect on the woofer low frequency response in terms of damping and the apparent low frequency extension. You might find while the bass is preferred overall that you somehow find the transparency or fine high frequency details are different. This is because you are processing the signal and some changes are to be expected. Like all things with high quality sound reproduction its subjective and personal taste comes into it.
This is only your first attempt and it may take some time to reach at pleasing level of enjoyment
Good luck
Ian
This has been my experience with every DSP I have used. I have found the image depth, inner detail, micro dynamics, and spatial qualities of a top flight analog system seem to get constrained or lost when digital conversion is inserted into the system.
In my new HT, the sound is amazing. The sound of a singer or instrument that is panned to the center is so well handled by my digitally ED'd and phase controlled D'Appolito LCRs that in 2 channel mode I had to unplug the center channel to prove to myself that the center was indeed off. The system is dynamic as hell and the EQ super neutral, but there is that lack of depth etc. that I notice in stereo from my 2 channel analog system. Obviously in a surround system this isn't such a big deal, but I'd love to have it all.
I doubt you will be satisfied with the DBX unit... and based on my experience I doubt you will find a DSP that fully satisfies. If you do, please let me know.
Widget
Hello Mr. Widget
"In my new HT, the sound is amazing."
Well plan on sharing why don't you start a thread!
Rob
"I could be arguing in my spare time"
OT!Hello Mr. Widget
"In my new HT, the sound is amazing."
Well plan on sharing why don't you start a thread!
Rob
When I have some time I will tackle that.
Widget
If you are into computer based audio there are several state of the art DSP software packages that don't kill dynamics or microdetails. One can obtain the ideal minimum phase response at the listening position using these tools. See https://www.youtube.com/watch?v=yfGAUvyvdNU for details.
Here is an example of biamping JBL M2 using 4 subs: https://youtu.be/yfGAUvyvdNU?t=4196
Good luck on your journey!
Thanks for all answers.
I have done some testing now. The details and imaging were lost in the MC275. Thats not what i wanted because i really like that amp, but its like that and its just to face it.
I also think that the driverack isnt really up to this job...have to find something else. It seems like many others use BSS and is happy with that..
Surely JBL must have done tests with using BSS DSP XO on all K2 speakers (including E2
If not else just because the flexibility and speed in exploring alternative setups compared to doing the same in a passive environment.
If such files indeed do exist, it would be wonderful if they could be made available to our community. Given the time passed since these speakers hit the market it should not be sensitive either, I guess.
The files for the M2 are readily available and I would hope that similar files do exist for the others, albeit maybe not in final production standard but good enough for us DIY to start from.
On DSP I would argue that a proper set up modern DSP with a "neutral" DSP chain is not detectable electrically or audible (except for a few clock cycles delay). If it is perceived to alter the sound, it may be attributable to the quality of the DSP algorithms in that brand/unit, poor level matching ( the ear is very sensitive to levels, less so to frequency), chosen DSP digital path is indeed not neutral (GUI lying?) or the input level to low giving the ADC to little voltage to work with.
The last point is easy to solve by increasing the level in or, especially in BSS units, by feeding digital signal (SPDIF, AES, BLU-LINK or USB (via BLU-LINK).
I have also tried many DSP's over the years and with the newer units (HW+SW) I can't detect or measure when such DSP is being punched in or out of my systems, A/B (various JBL's of pretty decent quality or my Genelec refs).
With BSS you can also use digital output cards and then use the DAC of choice, to eliminate any bias related to that area.
The M2 is a fully digital DSP system and I don't think too many would argue that it is not analytical or detailed. Worth noting is that some of my contacts in BSS (UK) are a little skeptical to the built-in DSP's in the Crown amps and argue that those are not the same as the stand alone units. Maybe the HD amps do have a full Soundweb, but the lesser units maybe don't.
Maybe that is why Harman is offering the M2's with a stand-alone DSP SDEC (JBL rebranded BSS BLU-160 unit) for critical installations. That is how they were set up their NYC show-room when I heard them the first time many years ago. They used ML amps. They were side by side with E2's. That was a day to remember! They also had the Revels but they were downstairs, so not easy to compare. I spend considerable more time there than what my better half though was warranted...
Most studio monitors are today DSP based (both near and mid field) and most sound real good, ref JBL LSR708. They often use FIR filters to be phase linear over the entire spectrum, something that is extremely difficult with passive filters. Most Genelec's are DSP based and use Fir filters. DSP just give you tools that are great. Pls see Genelec curve below.
I know that Mr. Widget do prefer his passive E2's to M2 (and probably rightly so) but I would suggest that it pertains mostly to the 476 being a better driver than the D2. I may even be so bold to suggest that an M2 with a 476Be (and potentially with a 045 UHF as the Be falls off quite early) would out-gun them both, if it was given the same amount of development as the M2. However, that would be at a price point that would not fit in the marketing positioning today.
I have been skeptical to the digital revolution but started with digital XO's in early 2000's. They were generally not so good back then. However they were like Pandoras Box, the advantage in ease and flexibility gives us DYI'ers possibilities that were impossible 20 years ago. Or at least slow and expensive. Even with less than stellar digital quality they were even then a decent trade-off back due to flexibility and the ability to do thing that is very difficult with passive arrangements (time/phase).
Today with the quality of digital audio and the dramatic price drop have made really good quality DSP's available to everyone (and exclusive passive components ridiculously expensive especially when building charge coupled filters). They do sound good and, as I see it, there are really no reasons to spend money and time to develop passive XO's that do have limitations the DSP does not, unless you really like passive filters or want to avoid the additional electronics needed.
But even the last argument is loosing ground as electronics is getting cheaper and smaller by the day. Take the Benchmark AHB2 power amplifier with lots of power, small footprint and better data then most "high street" very expensive power amplifiers. It may not be enough to power a pair of E2's but plenty for the rest of us. A DAC that outperforms any 5 year old expensive High End DAC can today be had for $150 and for $700-1200 you are in High Street $25k territory. Wonderful.
Just my 25 cents
//Rob
Below Genelc 8340 curve on the bench in my shop 1,3m out, 5ms curve (so some reflexes) and NO SMOOTHING. Not too shabby. (LSPCad + Calibrated Earthworks mic on Focusrite Solo V3)
The solution to the problem changes the problem.
-And always remember that all of your equipment was made by the lowest bidder
Hi Rob,
You make some interesting points.
I would say that not all Diy DSP users or audio amateur users of DSP are created equal or have your skill level with DSP active crossovers. In fact some don’t have the vaguest notion of what such equipment can do or how it works. It’s a specialised niche area. They know about CD players and home theatre receivers. A little bit of knowledge can sound like fun but in the hands of a lay person there are many barriers to a successful outcome.
As to your comments on the JBL consumer loudspeakers from what l know Harman steered right away from promoting active crossovers for their consumer systems. The JBL Synthesis receivers and processes may have Bi amp programming for JBL synthesis HT loudspeakers. That’s a niche area.
It’s a “thing” the hifi industry is sensitive about. If someone bucks the trend they can find themselves out of business. The DD67000 was conceived as a tri amp loudspeaker. That involved the woofers and the horn but not active horn EQ. Harman weren’t interested in promoting it as an active system so it as bought to the market as a passive system.
Associated with this is the significance of the vinyl aspect of sound reproduction which despite the “tech” in hifi is still very popular. Virtually all major HiFi brands are marketing turntables these days because if they don’t they will miss a big share of wallet. People who are invested in vinyl don’t like converting analogue back to digital and then back to analogue. That’s not going to change.
The diy or audio amateur space is a niche with a long legacy associated with what is now a luxury mens toy industry. Although it’s merged with a much larger home entertainment industry. The diy audio space is a lot more sensible than hi end Hifi. Personally l would rather spend $27.000 on 300 hp jet ski that will do 0- 60 mph in under 5 seconds with a hot babe enjoying every moment of it.
https://www.sea-doo.com/au/en/models...nce/rxp-x.html
I think it also worth noting that the studio environment even a home studio is in a number of respects different to home entertainment dsp platform.
In a simplified explanation the recording process and the associated monitors are run at the native digital standard of the equipment in use via the digital mixer and other relevant hardware. There is no digital conversion until the recording is mastered for a particular consumer media.
On the other hand at home the diy /audio amateur is reliant on a music streaming provider, a music streaming hifi component, DA conversion either before the use of a dsp based crossover or after the dsp crossover.
The problem as reported widely by users is the significant variation in recording standards. To a lesser extent HIFi music streamers vary in quality less in relative terms.
Even Tidal MQA which l have subscribed to has wide variations in the quality of the recordings that have been MQA mastered to the original artist or producers requirements. You can’t make a silk purse out of a sour’s ears.
Therefore it comes back to the recording along with the loudspeaker and it’s interactions with the room which are the weak link.
I am not disagreeing with you. Just that in the context of a bigger picture there are answers to some of your points. If it was a perfect world and we could predict everyone’s scenario and individual needs it would be up for discussion.
I have come up with what is analogous to an algorithm for distillation of the diy /audio amateurs scenarios and needs down to specific analogue active crossover requirements. It’s very much a systems driven approach in which the users needs are carefully assessed and predicted across a range of loudspeaker systems.
It’s a bit like modern lego. You can make anything out of lego as long as it’s been thought about by the developer.
Hello Ian
Happy New Year!
Nice Ski!
The funny thing is I have limited experience with digital actives just use them in my Crown subwoofer amp. I just imputed a couple of filters to replicate what a BX-63 A does. The advantage being having a BX-63A to measure and see what the voltage drive actually is beyond anything printed in the brochure. Have built DX-1 cards and used LEAP to do a bi-amp conversion of L250 Jubilee by matching the voltage drives. Doing analog active/ passive crossovers gives you a huge leg up for understanding how to use DSP for a crossovers and do the conversion.
I think your crossover project has good merit and would be a perfect solution for this case if the desire was to stay analog and avoid DSP. When you see questions like the OP asked on a public forum you can see a real need to have good technical support for using these DSP crossovers beyond the presets. Your idea of doing system specific support is spot on.
If you get a response online how do you know it's correct?? If you get 2 and they are different which one do you choose?? How do you know who to listen too??
The problem is aside from the manuals and the general tech support from the manufacturers specific system set-ups for systems that are outside the system presets is very limited.
From the manufacturers point of view you take a lot on chances making a system "bi-amp ready" and then just post a voltage drive and that's it??
Is the assumption that you can get this kind of technical support through the dealer??
You go through all the trouble of making a passive crossover, voicing the system and then throw it all out the window with no bi-amp presets or technical support?? Nuts!
Rob
"I could be arguing in my spare time"
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