I'm looking at my options for DSP crossovers, and the DBX Driverack Venu360 seems my strongest option.
DriveRack VENU360 | dbx Professional Audio
The problem with that option is that because it's for a triamp setup, and I'm not running a mixer and matching levels etc, I need a volume control post-unit. Pre-unit would lead to low input levels and lead to noisy/truncated performance.
Right now I'm leaning towards this minimalist solution-
Overview
Combined with the breakout cables needed, that puts me at around $1500 all-in- not a piddling investment but having a good volume control and full DSP with either line-level analog or AES/EBU inputs will be extremely flexible and ensure that I'm not feeding the driverack with low-level signals that will underperform when I'm using the analog input.
I don't really want to build a 6ch volume control using premium goodies, or turn more than one knob, so the SPL Volume 8 seems to be a solid choice (knowing that it's single-ended on the potentiometer).
Any thoughts? Anyone found a solid 6ch balanced volume control option besides this? Is there a $1500 DSP I'm missing that would do stereo 3 ways, well, and not require the additional box? One alternative is analog XOs, but I like the power and flex that the Venu affords me for other uses besides this project.
DriveRack VENU360 | dbx Professional Audio
The problem with that option is that because it's for a triamp setup, and I'm not running a mixer and matching levels etc, I need a volume control post-unit. Pre-unit would lead to low input levels and lead to noisy/truncated performance.
Right now I'm leaning towards this minimalist solution-
Overview
Combined with the breakout cables needed, that puts me at around $1500 all-in- not a piddling investment but having a good volume control and full DSP with either line-level analog or AES/EBU inputs will be extremely flexible and ensure that I'm not feeding the driverack with low-level signals that will underperform when I'm using the analog input.
I don't really want to build a 6ch volume control using premium goodies, or turn more than one knob, so the SPL Volume 8 seems to be a solid choice (knowing that it's single-ended on the potentiometer).
Any thoughts? Anyone found a solid 6ch balanced volume control option besides this? Is there a $1500 DSP I'm missing that would do stereo 3 ways, well, and not require the additional box? One alternative is analog XOs, but I like the power and flex that the Venu affords me for other uses besides this project.
This a dubious claim from their blurb :
"In contrast to passive volume controls which alter the phase and frequency response there is no alteration in sound with an active volume control"
I use this Alps Rk16816mg 6-way High-end Motor Potentiometer 10k Logarithmic | eBay with a Behringer DCX2496
"In contrast to passive volume controls which alter the phase and frequency response there is no alteration in sound with an active volume control"
I use this Alps Rk16816mg 6-way High-end Motor Potentiometer 10k Logarithmic | eBay with a Behringer DCX2496
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If instead of using HARDWARE to do DSP you used SOFTWARE you could pay a fraction of the cost, and do the volume control/balance in software, even interface to an external knob if you want to set global volume levels. Ten years ago this was the way to go, but not anymore. You now need a small, low cost linux computer, some free software, a multichannel onboard sound card or external USB multichannel DAC (and ADC if you want to process the audio from other analog components), and some time to bring it all together. This page is an example of what you can do:
Digital Crossover/EQ with Open-Source Software: HOWTO | Richard's Stuff
I only use this approach now for loudspeaker crossovers and DSP where I previously (10 years back) used a Behringer DCX2496 and then (5 years back) some different miniDSP boxes. I can do more and different stuff under linux, and that makes it a more powerful and versatile solution for my systems.
If you want a self-contained, ready to roll solution (which the Linux way is not), then check out miniDSP products.
I use their 4x10 to do a stereo three way crossover (it can handle four way). There is a master digital volume at the digital processing output, controlled with any IR remote or the front panel knob. See their website for products/info.
Creating a DSP crossover requires different software tools than passive xover and ideally these tools match the hardware you buy. There is an excellent Excel based program to do almost all the work with the family of miniDSP products I use.
Interestingly the author of this program is (wait for it) Charlie Laub!
Charlie have you written a page somewhere with the tradeoffs between miniDSP and the Linux box solution?
I use their 4x10 to do a stereo three way crossover (it can handle four way). There is a master digital volume at the digital processing output, controlled with any IR remote or the front panel knob. See their website for products/info.
Creating a DSP crossover requires different software tools than passive xover and ideally these tools match the hardware you buy. There is an excellent Excel based program to do almost all the work with the family of miniDSP products I use.
Interestingly the author of this program is (wait for it) Charlie Laub!
Charlie have you written a page somewhere with the tradeoffs between miniDSP and the Linux box solution?
Not really, if you set it up right. I've run that way for years and it's every bit as good, if not better, than analog control post x-over.
If you set up your gain structure properly, you'll only need about 10dB of volume control. Since most software will be working in 32 or 64 bit float, that's not a problem. Your DAC might be 24 bit (still no problem) with an effective 20 bits of S/N. That's still huge.
Digital attenuation is a problem I worried about for years, until I actually listened to it and measured it. Doing it right isn't difficult and the results are worth it.
Thanks for the thoughts guys. Pano, I need this to be relatively flexible for different configs- I can't always run a decent input voltage IF I'm controlling level on the input side. 10dB won't cut it for me on control range.
Charlie, PC based is stronk for sure- I get hung up on a good multichannel balanced dac/sound card, as well as concerns on noise etc, but I guess those can be mitigated in a modern setup. I'd want something I can leave up to enable the wifely unit to operate things without too many headaches.
Mark: I haven't seen a good master gain solution in the venu documentation anywhere. The presence of that would go a long way, I'll keep looking.
MiniDSP doesn't quite meet what I think I want in terms of power and flexibility, same with behringer and a vol pot.
So PC needs some more review, I'm not sure I'm okay with adding the SPL unit just to have a decent VC, even though it seems well-suited to this app.
Charlie, PC based is stronk for sure- I get hung up on a good multichannel balanced dac/sound card, as well as concerns on noise etc, but I guess those can be mitigated in a modern setup. I'd want something I can leave up to enable the wifely unit to operate things without too many headaches.
Mark: I haven't seen a good master gain solution in the venu documentation anywhere. The presence of that would go a long way, I'll keep looking.
MiniDSP doesn't quite meet what I think I want in terms of power and flexibility, same with behringer and a vol pot.
So PC needs some more review, I'm not sure I'm okay with adding the SPL unit just to have a decent VC, even though it seems well-suited to this app.
Yeah, that Venue360 manual is one bugger to figure out IMO !!
It's a bit more $$, but I have a Danley SC-48 (Linea-Reseach ASC-48) that I can highly recommend. 4x8 analog or aes3. Great global/individual control/routing, rms and peak limiting, and the equivalent of linear phase LR24s that can be moved on the fly, with timing staying in place between output channels. it's pretty slick...
The dB-Mark XCA48 has some interesting specs and its cheaper (£485) than the Venue 360:
I have a miniDSP 2x4HD that i will use for a 2 way crossover for a TPL-150H + AE TD12M, but some users have reported some hiss with high sensitivity CD's, so if face the same with the miniDSP i'm considering trying the dB-Mark.
- DAC Chip: Texas Instruments PCM1798
- ADC Chip: Asahi Kasei AK5388
- DSP Chip: Texas Instruments TM320C6726
- Op Amps: Texas Instruments MC33078, ST Microelectronics MC33079
I have a miniDSP 2x4HD that i will use for a 2 way crossover for a TPL-150H + AE TD12M, but some users have reported some hiss with high sensitivity CD's, so if face the same with the miniDSP i'm considering trying the dB-Mark.
Understandable, it can be source dependent.
I don't use a CD player, doing all file playback from hard drive via a software player. For phono I used a preamp with volume control, then a stand alone audio card to go from analog to SPDIF, then on to the crossover. With all that I was surprised to find that a range of 10dB was plenty. I expected maybe 20dB or more.
IME, getting the system set up so that every source can be used over a volume range of ~12dB is well worth the effort. Digital volume control is super clean.
Particularly if it is done by adjusting the DAC voltage reference, a pity it isn't standard practice. Otherwise it will depend on available bit depth
Sorry, but I don't understand the fear of loosing S/N or dynamics or sound quality with level adjustment, with dsp systems. First, you must have at least 24-bit or processor, rest is easy.
I have almost four years experience with minidsp 4x10HD and one year with 2x4HD. Both get analog signal from preamp, and in most challenging setup I have 3 DA/AD conversions and digital/analog level adjustments chained. Never heard any hiss or lowered dynamics! I suppose that to get in trouble, you must try really hard to do many things wrong!
Gain should be such that when source is giving maximal voltage, dsp/xo almost gets overloaded and power amp starts to distort. I don't have quite this but close. Hiss or hum can be heard at full spl setting without signal, but it is induced in analog interconnects. Spl with signal at 2 meters is then something like 110dB from a single loudspeaker, and still if I turn it down to 30-40dB sound is still very clean.
I have also tested minidsp 4x10HD with digital input from a CD-player, but it sounded just the same. My sources are laptop, CD, FM-radio, TV and BD. The "preamp" is 2002 model Yamaha RX-V830RDS and all signals go through it's DA and digital volume control, analog to minidsp. It works also as power amp for center and rear channels of 5.0 listening. Works like a train's toilet! And was voted to give best sound in a national diy event!
I have almost four years experience with minidsp 4x10HD and one year with 2x4HD. Both get analog signal from preamp, and in most challenging setup I have 3 DA/AD conversions and digital/analog level adjustments chained. Never heard any hiss or lowered dynamics! I suppose that to get in trouble, you must try really hard to do many things wrong!
Gain should be such that when source is giving maximal voltage, dsp/xo almost gets overloaded and power amp starts to distort. I don't have quite this but close. Hiss or hum can be heard at full spl setting without signal, but it is induced in analog interconnects. Spl with signal at 2 meters is then something like 110dB from a single loudspeaker, and still if I turn it down to 30-40dB sound is still very clean.
I have also tested minidsp 4x10HD with digital input from a CD-player, but it sounded just the same. My sources are laptop, CD, FM-radio, TV and BD. The "preamp" is 2002 model Yamaha RX-V830RDS and all signals go through it's DA and digital volume control, analog to minidsp. It works also as power amp for center and rear channels of 5.0 listening. Works like a train's toilet! And was voted to give best sound in a national diy event!
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Well yes, as said above. And 24 bits is plenty. Even the real world S/N performance of most DAC circuits equivalent to 20 bits is plenty.
Yeah, DACs don't seem to be a problem with gain staging anymore.
I get hiss with multiple AD/DA conversions in the signal chain...so I'm led to speculate that AD conversions aren't in the same league as DACs yet..but that's pure speculation......
I just try to keep everything digital till the last DA conversion.
Right now my "A signal" rig is jriver, to a x-32, to a midas DL-155 I/O box, to 4x opendrc's, back to the DL-155..all digital.
Then the DL-155 performs 8 channel DAC duty.
And I keep amp gain as low as works...
This gives me about a 30dB working range..with low hiss and room to crank...on a system about 103dB 1 watt..
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I agree that digital volume control is the way to go, avoiding additional A->D / D->A conversions as much as is practical for your routing. https://www.rme-audio.de/download/adi2pro_e.pdf Page 89 has a good technical explanation of how to do digital volume control “right” without losing fidelity.
