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Active Bi-Amping/Tri-Amping FAQ


Chris A
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I ran a stack of Yamaha Pro P2500s amps in my old HT, and they were great...absolutely zero fan noise. I will be running 2 pair of them in my new setup for my height channels too.

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1 hour ago, robi2 said:

1)Do you think exist in miniDSP lineup a similar product that could provide 6 (or more) digital outputs too ???

Perhaps you can draw a picture of what you're trying to do.  I'm a bit confused as to where you're heading. 

 

Chris

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  • 2 months later...

I'm aware that there is a Dayton Audio 4 in, 8-out DSP crossover that sells for $150 or less from Parts Express.  There is a thread at diyAudio on this box:

 

https://www.diyaudio.com/forums/digital-line-level/347871-dayton-audio-dsp-408-a.html

 

There is also a tear-down article on it in Japanese referenced from user CyberPit at diyAudio.  Here is a link to that article translated by Google Translate:

https://translate.google.com/translate?hl=en&tab=wT1&sl=auto&tl=en&u=https%3A%2F%2Fcyberpithilo.web.fc2.com%2Faudio%2Fopenit%2FDayton_dsp%2Findex.html

 

It looks as if this device has some potential, but also some potential for noise, etc., if not careful.  Read the diyAudio thread carefully and also any comments over at Parts Express to understand if this little box might work for you.  Caveat emptor definitely applies to this one.  If anyone decides to spring for one and tries it out, let us know here how it performs with high efficiency loudspeakers.  If it performs well enough, this would represent a 72% decrease in the price of a 4-in, 8-out DSP crossover over the miniDSP 4x10 HD unit (also a 4-in, 8-out unit).  That's big news...in that it would undercut the price of passive crossovers for a stereo 3-way setup with subwoofer.

 

Chris

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I haven't followed the market on consumer-level DSP units, so I'll ask here. Do any of them come with a true SDK? I don't mean just being able to string together processing blocks and specify filter parameters; I mean a true software development environment so that the user can write custom programs in, for example, C or assembly.

 

I think that it would be fun to create a software library specifically for Klipsch products. I have the knowhow for both the signal processing and the programming. I suspect that others here do, too.

 

- Greg

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I did a quick search--and no one that I can see currently offers SDKs for their products.  In fact, miniDSP support techs on their forum specifically swore off trying to support "engineers in a third party debug of their code over and above the basic support of their products". 

 

I suppose that it will still take a while for a "Raspberry Pi DSP crossover" to appear.  As you have already stated, most Linux installations aren't really real time OSes, among other issues that you've raised in the support environment. 

 

I believe that as the DSP crossover market moves in to gradually supplant passive loudspeaker crossover networks, even small loudspeaker manufacturing companies will catch on and begin to realize what the potential means to their products if they adopt early, or what happens if they don't...

 

Chris

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I definitely agree about the potential. 

 

Really, the affordability of such units can now be applied widely and provide big, big improvements.

 

There are some other roadblocks that will then become the challenges in properly implementing these tools (measurement, goals etc). It will be interesting to see how it all spins out.  It will also be interesting to see how the hucksters try to corrupt (or is co-opt) this endeavor. 

 

Good luck,

-Tom 

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41 minutes ago, Chris A said:

I did a quick search--and no one that I can see currently offers SDKs for their products.  In fact, miniDSP support techs on their forum specifically swore off trying to support "engineers in a third party debug of their code over and above the basic support of their products". 

 

Yeah, I ran into exactly that when I inquired directly to miniDSP.

 

Quote

I suppose that it will still take a while for a "Raspberry Pi DSP crossover" to appear.  As you have already stated, most Linux installations aren't really real time OSes, among other issues that you've raised in the support environment.

 

This looks like a promising alternative to Linux on the Raspberry Pi: https://ultibo.org, but I haven't had time to look into it.

 

- Greg

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  • 1 month later...
On 11/7/2019 at 4:49 AM, Chris A said:

None that I'm aware of accept optical inputs.  The requirement for 2-in (assumed), 6-out is also difficult to find.  I see amplifiers like the following 8-channel I/O DSP amplifiers (which I know nothing about):

 

https://www.qsc.com/resource-files/productresources/amp/cxd-q/q_amp_cxdq_8ch_specs.pdf

 

In short, I think that a separate DSP crossover box with S/PDIF (TOSLINK or coaxial) connected to a 6 channel amplifier box is a much more likely configuration--like a miniDSP 4x10 HD with your choice of multi-channel amplifier (6 channels in your case, leaving two unused output channels from the 4x10 HD).  I'd recommend balanced connections (XLR) to reject common mode noise.

 

Chris

 

Hi all, new poster here.  May I first say, it's been very enjoyable and informative studying many threads and posts on these klipsch community forums.

Hope to try making a DIY K-402 MEH soon ! 

Maybe in exchange i can provide some info about the qsc amp that Chris A linked...

 

I'm familiar with the QSC CXD-Q amplifiers, owning a couple of the 4 channel models.

They are network amps that connect via Ethernet to a QSC Core processor. A Core processor is mandatory.

QSC makes a number of different Core processors, with the smallest, the Core110f  being the most flexible in terms of  built in I/O capability.

 

Unfortunately, I'd be reluctant to recommend any of the CXD-Q amps for home use, simply because their fans are loud. 

It's a crying shame because they do provide a multi-channel digital signal flow solution, between processor and amps.

 

The Core110f processor however, I can wholeheartedly  recommend to anyone looking for a multi-channed dsp.

It uses the Q-SYS Designer software to make open architecture processing schematics.  

The flexibility is awesome....you can design just about anything.  I'm running 8 channels with 4096 taps of FIR on each channel.  Along with traditional IIR EQ banks, timing, levels, peak and rms limiters, etc.

It has 8 balanced mic/line inputs, 8 balanced mic/line outputs, and another 8 channels that can be independently configured as inputs or outputs. USB 16x16.

It's silent too :)  About the only negatives are no AES/spdif inputs, and 48kHz only.

 

Another network amp solution with Q-SYS is to use what QSC terms an I/O frame and connect to any of their amps which have data-port connections.

The amps are their CX install series, and Powerlight touring series.  The only issue with these is the damn fans in the I/O frames are also loud.  Not nearly as loud as the CXD-Q amps, but not quiet either.

 

I got my q-sys stuff off ebay. It's robust enough I feel used is fine.  The Core110f typically trades for $1200 - $1800, from used to like-new. The CX amps go for peanuts compared to new.

 

Previous processing  rig was 4 openDRC DI's connected to an 8 channel Midas digital I/O/DAC box. Worked super, but at twice the cost of the Core110f, and not nearly as flexible.

 

Apologize if I sound like a q-sys shrill....it's just it's so dang hard to find the processor we need...and when we do !! :)

Edited by Mallette
First post with commercial links.
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1 hour ago, Mallette said:

No links in first post to anything commercial. You may post now but review the TOS first.

Dave

Sorry, my bad.  I saw the link in a previous thread to the qsc 8 ch amp., and thought product links were aok.

But i now see the link is a spec sheet....so i guess pure specs links are fine, anything else is a no-go?

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12 minutes ago, gnarly said:

But i now see the link is a spec sheet....so i guess pure specs links are fine, anything else is a no-go?

No. You can post product links but but if you do mainly that and for only one or a couple of sites you may be monitored to determine whether you are touting something you have an interest in. You may post freely now... We just don't have time to check every link on first post, so most of us delete them. You may repost those links now if you wish.

Dave

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1 hour ago, Mallette said:

No. You can post product links but but if you do mainly that and for only one or a couple of sites you may be monitored to determine whether you are touting something you have an interest in. You may post freely now... We just don't have time to check every link on first post, so most of us delete them. You may repost those links now if you wish.

Dave

Understand,  makes sense..cool to have such moderation in place.

And there's no reason for me to repost the product links....they were out of simple courtesy, to keep someone from having to search.

 

 

 

 

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  • 2 months later...

Hi All.  This is a great thread that has been very informative and helpful.  I do have a question that I don't think was covered so far.  I have a 2 in/4 out electronic crossover, the XTA DP200 and would like to use it as a crossover for the tweeter and mid-range horns in a La Scala that will allow me to time align them.  My plan is to run the bass horn through its stock passive crossover (AL-3) and then use the XTA DP200 to feed the tweeter and mid-range.  Is this not preferable to using the DP200 to split the signal between LF and MF/HF and using the passive to split the frequencies going to the mid-range horn and tweeter?  Any thoughts and input you all may have would be most appreciated. 

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7 hours ago, Tizman said:

Is this not preferable to using the DP200 to split the signal between LF and MF/HF and using the passive to split the frequencies going to the mid-range horn and tweeter?

 

Yes.  The greatest time misalignment in the La Scala II (i.e., generally the same as the original La Scala) is between the tweeter and midrange drivers/horns.  Here is a spectrogram (on-axis) from REW that shows the several-wavelength relative time misalignment at 4.5 kHz between the tweeter and midrange, and again at 400 Hz but only about a wavelength mismatch between the midrange and bass bin:

 

LSII spectrogram showing 1.723 ms tweeter to midrange delay.jpg

 

Just add about a 1.7 ms delay to the tweeter channel (La Scala II).  If you want to dial it in closer, then take a REW measurement in-room.  Then we can see SPL and phase response to dial everything in much closer.

 

Here is the same spectrogram plot for a tri-amped La Scala II using a Xilica XP4080, and completely dialed in:

 

1939614125_LaScalaIITr-ampedusingXilicaXP-4080spectrogram.thumb.jpg.6f9e3a0dafcbd8a05f45d32e937d4043.jpg

 

Chris

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9 hours ago, Chris A said:

Here is the same spectrogram plot for a tri-amped La Scala II using a Xilica XP4080, and completely dialed in

  
Thanks Chris.  I think that I can use delay on the midrange and tweeter relative to the Incoming signal feeding the bass bin to get all three in alignment.

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  • 11 months later...

Older thread but hope people will respond. 
Super basic question about the digital to analog signal chain.

is the common method for a digital source go Streamer...Dac...preamp...Xilica...amp...driver?

so it’s digital to analog back to digital, back again to analog.

Just checking that this is the signal path for digital sources.  Or do people eliminate the preamp and stay digital as long as possible?

thanks, Ted

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2 minutes ago, VDS said:

Older thread but hope people will respond. 
Super basic question about the digital to analog signal chain.

is the common method for a digital source go Streamer...Dac...preamp...Xilica...amp...driver?

so it’s digital to analog back to digital, back again to analog.

Just checking that this is the signal path for digital sources.  Or do people eliminate the preamp and stay digital as long as possible?

thanks, Ted

 

So i've been tinkering with both since my yamaha DSP has both analog and AES inputs. So I've done analog pre-outs from my AVR where there's a D/A to A/D to D/A conversion, and then variations of DACs/Streamers with digital passthrough at 24/96 so the only DAC conversion is at the final stage within the Yamaha. There's a difference, but I think it has more to do with the gain structure differences between the analog and digital connections, rather than the additional ADC/DAC conversions.

 

One thing I found ultimately annoying with the all digital chain was that I was left to use the little app-based volume sliders which can be pretty fiddly and annoying over the long term. So my latest iteration is a benchmark dac2 with a remote that I can use as both a headphone amp and pre-amp in front of the yamaha. I haven't used the pre-amp function yet, but I'm confident that this piece of kit is competent enough that any degradation in sound with the extra conversions will be entirely inaudible by me.

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  • 1 month later...
  • 2 weeks later...
On 6/14/2021 at 10:16 AM, parlophone1 said:

Curious about Benchmark too.

I have been looking adds for quite some time, but there were more important things to solve.

Report back how is DAC2 in your system.

 

As far as headphone systems go, it's a really solid piece. I haven't integrated it into my main stereo system yet (it and my headphones are currently at the office so I can use them more), but I anticipate it working quite well as a dac/preamp.

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