DIY tri-amped 2226 2445 2405 system update

[danvprod]

I figured it was time to do an update on my system in a new thread, since I've made considerable changes. It's still in a state of flux, but I believe moving in the right direction.

The system is comprised of JBL 2226J, 2445J and 2405Js. Previous set up was to run everything through a MiniDSP 2x4 with a passive 8 kHz crossover to the 2405.

Added a new DSP to the system: Xilica XP 4080. I had gone back and forth on what DSP to use. I ended up with the Xilica has I found one on eBay for the same price as a MiniDSP 4x10, and I think the Xilica is in another league. Setup of the Xilica was not as easy as the MiniDSP (software is not as nice), but once it's up and running having the metering on the front and the mutes on inputs and outputs are really nice.

Previously I had been running my 300B mono blocks for the 2405/2445 and a Rotel RB1050. I am now running a Pioneer VSX-D912 after getting some pretty stellar recommendations to do so from AudioCircle. I do consider it a temporary solution, but it is working OK. It's nice to have 6 channels of application in a single device. (My 300Bs need some repairs done to them -- I will likely have them back powering the 2445Js when I get them back).

Once it gets a bit nicer outside, I need to get this out and measure them and tweak the crossover. Right now I am running the following:

2226: LP 500 Hz 24 dB/Octave; +8 @ 35 Hz, Q 1.1 (Thanks, Lee).
2445: 47 uF Dayton Protection Cap, HP 500 Hz 12 dB/Octave; LP 8000 Hz 24 dB/Octave; - Polarity (In Xilica) -- -20 dB Gain
2405: 2.2 uF Dayton Precision Audio Cap, HP 8000 Hz 24 dB/Octave. -15 dB Gain

I have the 2226 delayed by .6 ms and the 2405 delayed by .8 ms.

Next step is to find a better audio rack, get the tube amps fixed, get my turntable hooked back up and figure out more permanent amplification (any suggestions?).

The Xilica has balanced outputs, so I was considering just running 3 power amps -- I had been looking at the Behringer Reference A500.
The balanced outputs and a potential negative of the Xilica in a home system, it would also be nice if it had a digital input. Right now I am running the output of my Apogee Duet into Analog input 1/2 of the Xilica. The Turntable will be in 3/4.

Anyways, would appreciate some thoughts and comments.

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[Lee in Montreal]

I encourage you to go to a full 3-way system with tweeters on their own amp. When you do so, I recommend either an amp with low power if it has output relays (20 watts?). Or any amp will do if it has no output relays. My experience with amps running output relays is that the power required to run those 2405 is so small that it tends to damage the relays. They kinda stick shut. No output unless you really crank the amp to unstick the relays, then reduce volume.

On the woofer, I suggest you test different Q values. Could be anything from 0.8 to 1.1 and it is a matter of taste. For a more natural sound, I recommend crossing to the mid at 12db or 18db per octave. I find that 24db sounds less natural. Especially when crossing at a "low" 500Hz. The Linkwitz-Riley mode has some advantages as the end result remains flat.

And your 2405 deserve better stands. Check my avatar ;-)

http://upload.wikimedia.org/wikipedia/commons/thumb/d/d7/Linkwitz_vs_Butterworth.svg/300px-Linkwitz_vs_Butterworth.svg.png

[.:hb:.]

The balanced outputs and a potential negative of the Xilica in a home systemNo problem at all. You just need XLR/RCA adapters or cables with the right plugs fitted on each end.

it would also be nice if it had a digital inputEssential in terms of quality. Adding a completely unnecessary D/A-, followed by an A/D conversion isn't a good idea at all.

[ivica]

....... For a more natural sound, I recommend crossing to the mid at 12db or 18db per octave. I find that 24db sounds less natural. Especially when crossing at a "low" 500Hz. The Linkwitz-Riley mode has some advantages as the end result remains flat.
....

Hi Lee,

Interesting observation. May be using compression driver with the horn around so low frequency ( 500Hz), driver&horn 12dB hi-pass characteristics 'interfere with' the network 24dB hi-pass characteristics, resulting in such not natural reproduction.
From your large experience, is it the same behavior recognizable if say over 1kHz, 24dB L-R crossover frequency filter is applied.

What about around 10kHz ?

Reagrds
Ivica

[Lee in Montreal]

Hi Lee,

Interesting observation. May be using compression driver with the horn around so low frequency ( 500Hz), driver&horn 12dB hi-pass characteristics 'interfere with' the network 24dB hi-pass characteristics, resulting in such not natural reproduction.
From your large experience, is it the same behavior recognizable if say over 1kHz, 24dB L-R crossover frequency filter is applied.

What about around 10kHz ?

Reagrds
Ivica

You are flattering me too much ;-) I don't have a large experience. Just a few observations. I think that at such low frequency (500Hz is maybe low for a comp driver) trying to extend down to 500Hz with a 24db slope is maybe taking the risk of loosing a few dbs down there. While with a 12db slope, you get some content from the woofer. I don't think 24db is a problem at higher frequencies.

As for L-R vs Butterworth, the diagram I posted explains clearly the benefit of L-R's flat response instead of getting a slight bump at separation frequency such as is the case with Butterworth.

BTW our hobby is great as it allow us to try so many options, and what could be heresy for somebody might end up being heaven for another. Give a man (or a woman) a couple of drivers and amps, and he will keep busy all his life... ;-)

Lee

[danvprod]

The reason I use 24 dB/octave on the woofer and 12 dB/octave on the midrange CD is because it's already falling off pretty steep below 500 Hz (about another 12 dB/octave). The combined result is a 24 dB/octave slope on both. If I wanted a 12 dB/octave, I'd have to move the crossover frequency up -- perhaps up to 750 Hz. But as you said: give a man a few drivers, amps and DSPs and you can keep him busy for a lifetime.

BTW, I decided to return the Xilica XP-4080 and stick get the MiniDSP 4x10 HD instead. This will let me run full digital in and avoid an extra A/D D/A in my signal path. And I still have an extra pair of analog inputs for my turntable and a volume control should I want to explore some different power amps.

Re: 2405 stands. Lee, do you want to make me some :)?

I really really really need to get these outside and do some quasi-anechoic measurement. Because right now I am just guess or relying on in-room measurements in my relatively small room and I can only learn so much from that.

[Lee in Montreal]

Re: 2405 stands. Lee, do you want to make me some :)?


I have two dozen units on the shelves. They are stainless steel. PM me if you want a set.

Lee

[danvprod]

Couple of updates on the system -- the MiniDSP 4x10 HD is working well. I've ordered a pair of aluminum stands for my CDs and some stainless steel stands for the 2405s from Lee. Thanks Lee! They should be here soon.

This weekend I purchased a new amplifier on eBay -- it's a JBL AVA7. Should be perfect for this setup. This is the same unit as the Lexicon LX7 amplifier which is manufactured in the USA by ATI, so I figured that can't be bad.

This will replace my Pioneer VSX D-912 receiver. Currently also trying to sell my 300B tubes amps, although I may test how they sound coupled to the 2445s with the AVA7 powering the 2226s.

[danvprod]

Very cool metal stands thanks to Lee:
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[danvprod]

I just received the JBL AVA7 that I purchased off of eBay, but I am a bit disappointed with the amount of hiss that is being put through the CDs and Super Tweeters. Even with nothing plugged into the input, there is a very audible hiss that can be heard at the listening position.

There are no level controls on the amp, so I have to trim the 2" CDs by 18 dB in miniDSP and the STs by 12 dB.

I would assume that this is causing the unwanted noise floor to be heard.

This amp is likely not the best choice for home for the CDs and STs, even though it is a really nice amp. I am bummed.

Would it be stupid to put an l-pad on the horns to act as an output attenuator on the amps?

The more I read, the more I think it was a bad decision to buy this.

Seems like people have had good luck power these types of systems with Crown D-45/D-75a (20/25 watts/channel into 16 ohms), Crown D-660 (25 watts/channel into 16 ohms). Both have attenuators on each channel, which would likely help.

Any advice would be appreciated.

[4313B]

Greg Timbers recommends a 6 to 10 dB resistor pad between the driving amp and the compression driver.

[danvprod]

Thank you for the suggestion. I tried a L-pad network on the 2445 this evening (10 Ohm parallel/10 Ohm series) for about 8 dB of attenuation. It definitely helped.

I think the AVA7 is just way overpowering the 2445/2405. Would you agree.

[Lee in Montreal]

I think the AVA7 is just way overpowering the 2445/2405. Would you agree. 2 x 10 watts would probably be enough. Solid state amp on bass and tubes on top. ;)

PS Did you find the enveloppe with the stickers in the box?

[danvprod]

Yes I found the stickers :) I still need to put them on.

Yea small tube amp is the right idea for the 2445/2405s. Ordered the parts for the crossover (mills resistors for the l-pads and protection caps for the 2445/2405s).

[danvprod]

Is there anything detrimental about using l-pads to improve the noise floor on the amps? e.g. 10 dB l-pad brings my 100 watt amp down to 10 watts (equiv) and drops the noise floor by 10 dB.

I also saw these little tube amps on amazon (3w x 2):
http://www.amazon.com/gp/product/B00APC0WWE/ref=ox_sc_sfl_title_2?ie=UTF8&psc=1&smid=A1V0149CC6WCAD

Might be good to power the 2405s? Or get 2 and power the 2445s with 1 and 2405s with the other. I'd replace the tubes immediately, but seems to be reviewed favorably.

Other option is a d-45 crown amp for the 2405s. I'd prob. still end up using the pad, I would think?

[BMWCCA]

Other option is a d-45 crown amp for the 2405s. I'd prob. still end up using the pad, I would think?

Why? The Crown has input attenuators.

[1audiohack]

The D45 is a 13 Volt output amp that will drive a whopping 14 Watts into the 12 Ohm load that ALL JBL ring radiators present to the amp.

I would also say that there is no good reason to put any passive components between the output of a D45 and the 240X that is actively crossed on the input side. Working properly the D45 has no transient on-off clicks or thumps. A nearly perfect amp for a pair of rings. :)

All the best,
Barry.

[BMWCCA]

I would also say that there is no good reason to put any passive components between the output of a D45 and the 240X that is actively crossed on the input side. Working properly the D45 has no transient on-off clicks or thumps. A nearly perfect amp for a pair of rings. :)

That's why I purchased three of them! ;)

[danvprod]

Well that may be the answer! Thanks for the input, guys.

[danvprod]

What are your thoughts about using the Crown D-45 vs. something like a low-powered SET to power the rings? Something like this: http://www.decware.com/newsite/SE84CKC.html

Obviously, there is a huge price difference. I could get a pair of D-45s (for the 2405s and 2445s) and an Adcom GF 555 ii (for the 2226s) for the same price as the SET and power my whole rig. Or pad down my CD/ST as I am trying to do now and keep the AVA7, which is a pretty solid amp, too.

Or maybe just let the AVA7 power the 2226s and pick up a pair of D-45s.

[JeffW]

I've never used one, but Emotiva has a passive attenuator to use with amps that have no means of adjusting the input signal.

https://emotiva.com/products/electronics/control-freak

Of course you'd need 1 unit for each pair of channels, just something else to consider.

There are other passive attenuators out there, but $50 is a pretty decent price point.

[pos]

Fostex has a cheaper version for those looking for unbalanced attenuation: the PC1-e, at around 25€.

[rusty jefferson]

..... it would also be nice if it had a digital input. Right now I am running the output of my Apogee Duet into Analog input 1/2 of the Xilica....

As stated earlier, having a digital input and avoiding the extra a/d transfer will be your largest source of improvement.


What are your thoughts about using the Crown D-45 vs. something like a low-powered SET to power the rings? Something like this: http://www.decware.com/newsite/SE84CKC.html


I don't think the Decware would be a good choice. It's essentially a current source amp designed for use with single driver type speakers. An EL-84 amp with no feedback means it'll have high output impedance, and I don't think that's what you're after. I can't comment on the Crown, but an excellent (imo), and inexpensive small amplifier for the task could be:
https://www.parasound.com/ParasoundZ/zampv3.php

[danvprod]

Thanks @rusty jefferson -- re: the D/A issue, I have switched the Xilica out for a MiniDSP 4x10 HD, which lets me go directly from my MacPro via Toslink optical, so no extra D/As.

Interesting thoughts on the Decware amp. Is this your opinion for both the 2405s and 2445s, i.e. that this type of amp would not be well-suited to drive these?

Thank you for the Parasound amp link, I will check that out.

@JeffW -- I'm not sure the emotiva attenuator would solve my problems, since the noise in my system is present even without anything hooked up to the inputs of my JBL AVA7. I think I need attenuators on the output of the amp in the form of an l-pad for corse level matching and then fine level matching done in the MiniDSP software. Ideally, the MiniDSP would be close to no attenuation for any of the channels, right now the 2445s have 18 dB and the 2405s have 15 dB, which is certainly attributing to my audible noise problem, I would think.

[rusty jefferson]

Thanks @rusty jefferson -- re: the D/A issue, I have switched the Xilica out for a MiniDSP 4x10 HD, which lets me go directly from my MacPro via Toslink optical, so no extra D/As.....


Sorry, I missed the update about the miniDSP. Have you experimented with a USB-S/PDIF converter? I've not heard an optical connection I thought was very good.



...Interesting thoughts on the Decware amp. Is this your opinion for both the 2405s and 2445s, i.e. that this type of amp would not be well-suited to drive these?...


Correct.



..Thank you for the Parasound amp link, I will check that out. ..


You bet. They are remarkably good (again, imo), affordable, and have level controls.

[danvprod]

I will definitely investigate adding a USB-S/PDIF interface. Right now the optical out of the MacPro is convenient. Any suggestions?

[rusty jefferson]

I will definitely investigate adding a USB-S/PDIF interface. Right now the optical out of the MacPro is convenient. Any suggestions?

My friend with a triamped system uses this one, apparently rebranded by several different seller. You should hear a significant improvement with this, or something like it, compared to the optical input. And, you can't beat the cost.
http://www.ebay.com/itm/CM6631-USB-DAC-to-Coaxial-fiber-192KHz-32bit-I2S-192K-24BIT-SPDIF-in-case/161615784487?_trksid=p2047675.c100011.m1850&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%2 6asc%3D29268%26meid%3D0c44cf79fa7d4ead8b2c13b3a9a3 c413%26pid%3D100011%26rk%3D1%26rkt%3D10%26sd%3D190 826768041

Here's another one. More compact, for use with a laptop, but also more expensive.
http://www.m2tech.biz/hiface2.html

[danvprod]

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My USB to S/PDIF convertor arrived today. Now I am going from my Mac Pro to the MiniDSP via USB and into the S/PDIF input. Very nice unit. The interface was a CM6631 USB DAC to Coaxial. $50 shipped. ~ 2 weeks to get here. Very happy.

Also managed to get 2 x Crown D45 very inexpensively. Currently have one powering the 2226s and one powering the 2405s. My 300Bs are powering the CDs. I also purchased a Parasound Zamp v3 yesterday, which should be here in a few days. I am going to swap that out for the 300Bs while they get some work done.

I'm going to compare the Parasound amp to the Crowns and decide which one makes the most sense.

I also purchased a Crown CP660 6-channel amp very inexpensively locally on CL. I am going to try that out as well and sell back what doesn't make it.

Sadly both of my Crown D45s make a pretty audible 'click' when I turn them off. I decided, at least while I am performing these experiences to build a simple protection network for the 2405s and 2445s. JIK I do something stupid. The D45s run cool and draw very little power at idle, I don't mind keeping them on.

I've been very impressed with the D45s ability to power the 2226s. And they seem like a nice match for the rings. I have the rings padded down 20 dB and everything trimmed to 0 dB in the MiniDSP, which is ideal. Everything is sounding very good ring now.

Some positives about the D45s:

Quiet as can be, especially with the rings. I have to really put my ear to the diaphragm to hear the hiss. This is several orders of magnitude better than the previous AVR and JBL AVA7.
Sound Quality is very good.
Runs cool and pretty compact at 1 RU.
Some negatives about the D45s are:

Audible turn off click heard through both the 2226s and 2405s.
Terminal block wiring is annoying.
On my 300B amps, I ended up trying to replace the rectifier tubes (5z4p) with a pair of NOS 5z4 RCA metal rectifier tubes. So far tonight's listening session has had minimal static interference. The metal tubes kind of scare me for some reason. And they run really really hot.

The USB DAC is a notable improvement over the stock digital out of the Mac Pro.

And everything is quiet -- even the 300b amps after replacing the rectifiers. I've been struggling so much with hiss, noise, hum and the like in the last few months, and it is nice to have this where I can listen and not be annoyed. I'll post some additional listening impressions with the CP660 and the Zamp. And take some photos of the protection network after it is done.

[rusty jefferson]

Glad to hear the S/PDIF converter is working out better than the optical.

There may be a small audible click at turn on from the ZAmp, but I don't think it's anything that would cause damage.

I see you've switched the speakers left for right from the earlier picture. I would have thought they'd sound a little better with the slots on the inside. They must be in the shadow of those horns, yes?

[danvprod]

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Found this nice stand at my local ReStore. Much better and cleaner looking than the two end tables. Better cable management, too and I can get to everything to make changes/adjustments.

I have to try with the slots on the inside and on the outside. It's easy enough to change, nothing is really tied down. I suppose they are in the shadows of the horns a bit, although the picture makes it looks worse than it is.

[danvprod]

I built my protection circuit for my 2405s and 2445s. Basically I have a 6dB/octave HPF with a bypass cap and a 47 ohm damping resistor wired in parallel with the driver. I can't hear it -- which I think is a good thing.

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[1audiohack]

That's really looking good! I can't hear it from here though. :(

All the best,
Barry.