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Multi-Way Conventional loudspeakers with crossovers

Thoughts on DSP multiamp/attenuator setup?
Thoughts on DSP multiamp/attenuator setup?
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Old 22nd May 2019, 07:29 PM   #61
KaffiMann is offline KaffiMann  Norway
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Thoughts on DSP multiamp/attenuator setup?
Every single bit increase on audio bit depth in sum just about double the theoretical reference points of signal resolution.
I honestly think that the potential signal degradation in the doubled amount of interconnects might have a slightly larger impact than a slight decrease in input signal on the adc.
It might be nearly impossible to measure any difference in signal quality between the two, so I think it is a waste.

Want higher quality? Use AES in and skip a conversion stage, live with digital volume control.
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Old 11th July 2019, 01:32 PM   #62
badman is offline badman  United States
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Originally Posted by KaffiMann View Post
Every single bit increase on audio bit depth in sum just about double the theoretical reference points of signal resolution.
I honestly think that the potential signal degradation in the doubled amount of interconnects might have a slightly larger impact than a slight decrease in input signal on the adc.
It might be nearly impossible to measure any difference in signal quality between the two, so I think it is a waste.

Want higher quality? Use AES in and skip a conversion stage, live with digital volume control.
For absolute best-quality digital you're absolutely right. If I get rid of the multipurpose functions of the stereo that would work better, however, my "big rig" is multi functional so the analog in was pretty important for general use (without separate A/Ds)

Regarding progress:

I finally got things hooked up yesterday Perfect example of "perfect is the enemy of the good", I was overthinking it before I even tried it. The network connectivity and software made it really easy to implement an EQ and crossover solution (right now I'm just using it as a sub processor/high pass filter for the 2 way mains). I wound up with some asymmetrical filters and notches, stuff that would have been very difficult with analog solutions.

We had a brownout while things were running (summer in new england) and everything fired back up cleanly afterwards, no scary pops or any such, which is very good to know both for peace of mind but also for power management solutions.

The 24dB attenuators were a good call, there would have been a lot of extra pre-dsp attenuation needed had those been excluded. Because it's a multifunctional system, sometimes volumes are very low (late night, background while working, etc) and other times more robust. The clipping settings in the DSP control gain structure, so there are a few levers to pull, but the analog attenuation was very helpful to have on the tops.

Key takeaways- unit doesn't have uglies on powerup/down, is working as intended, seems to be as-new from proaudiostar (at a very affordable $419). The software is limited in that some setup functions are front-panel only, but you can make full, high-resolution adjustment to everything that needs repeated tweaking- filters, XOs, EQ, compression, etc. Sound quality, I can't speak to as yet. It seemed to be a very neutral device, but it was a setup with a lot of changes happening so I can't speak to much of the little things.

I'll update as I continue to play with this setup- adjusting crossovers live from a networked laptop is very, very fun, and I can break out the other toys pretty fast and try some other serious stuff.
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Old 11th July 2019, 01:39 PM   #63
KaffiMann is offline KaffiMann  Norway
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Thoughts on DSP multiamp/attenuator setup?
As long as you think it's worth it that's all that matters.
It would be nice if you would try to compare with/without the extra proaudiostar kit, if it is at all possible to try remain semi-neutral during testing.
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Old 11th July 2019, 01:55 PM   #64
badman is offline badman  United States
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Originally Posted by KaffiMann View Post
As long as you think it's worth it that's all that matters.
It would be nice if you would try to compare with/without the extra proaudiostar kit, if it is at all possible to try remain semi-neutral during testing.
Wow, somebody answers fast! The attenuators were from Naiant, I'm assuming those are what you mean. Proaudiostar is just the place with the great price on the Venu360 DSP itself.

I'll experiment with and without the attenuators as I get used to it, but we're going to be talking some pretty severe sensitivity differences in some cases. The tops are some 96dB or so, while the subs are probably 86 in their passband, but they're EQ'd to operate below Fc (sealed and boosted). When we get into 3 ways with a 108dB comp tweeter, high 90s efficiency midwoofer, and low efficiency subs, every way to adjust levels will come into play I'm sure.
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Last edited by badman; 11th July 2019 at 02:04 PM.
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Old 11th July 2019, 03:12 PM   #65
bentoronto is offline bentoronto  Canada
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Thoughts on DSP multiamp/attenuator setup?
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Originally Posted by badman View Post
...Because it's a multifunctional system, sometimes volumes are very low (late night.
I'm all digits until the DSP output into the amps. At that point, easy to make a little box with ganged pots (4 of them) to control the volume (2 mids, 2 subs) with a single knob. Couldn't be easier to make or work better.

B.
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Old 11th July 2019, 07:19 PM   #66
badman is offline badman  United States
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Originally Posted by bentoronto View Post
I'm all digits until the DSP output into the amps. At that point, easy to make a little box with ganged pots (4 of them) to control the volume (2 mids, 2 subs) with a single knob. Couldn't be easier to make or work better.

B.
Right now I only use 4 channels, balanced, but likely this weekend I'll start with the serious stuff, using separate driver channels etc. 6 channels isn't really any harder to do, but if they're properly balanced... that's now 12 gangs. It's getting a little squirrely at that point, not to mention pots are the noisiest and least consistent performers out of pretty well all passive components (speakers get a pass).

I spent enough time building stepped ladder attenuators, wiring transformer volume controls, and all that jazz to know the pitfalls- I've done everything from single-stage stepdown with a mil spec pot hung off the back to relay-controlled ladder networks, and just fixed-attenuation for entire systems- couple resistors in-line, swap them out to change level. Knowing what's to be lost makes a compromised volume control a hard sell for a guy like me- even if my ears aren't what they were when I was designing those types of solutions some years back.

What I'm really looking forward to trying out are some of the horn bits- I'd previously used analog XO primarily, whether active, passive, or hybridized. Being able to just throw a curve at a horn is going to be very satisfying indeed, particularly when some things just don't fit right. The best measurements I've ever seen from a top octave were from a modified dome tweeter attached to a deep horn with a foam collar to keep device diameter small but add additional directionality below the natural device cutoff.

I took all the time prototyping the device, and made a solution that worked amazingly well as a supertweeter for a wide-band midrange type system, but never could make the XO work for a supertweeter in a horn system. Now, I just will throw protection caps on that and the main horn, hook 'em up to amps, and away I goes.
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Old 11th July 2019, 07:43 PM   #67
bentoronto is offline bentoronto  Canada
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Thoughts on DSP multiamp/attenuator setup?
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Originally Posted by badman View Post
... Knowing what's to be lost makes a compromised volume control a hard sell for a guy like me.
OK, no need to go into the arithmetic of noise from pots at the far end of the chain. Just think about this: compare the natural ease and precision of twisting a knob which is perhaps at arm's length to your chair (like mine is) to fooling with a graphic interface.

(Not sure where you get 12 pot count from?)

B.
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Old 11th July 2019, 08:29 PM   #68
badman is offline badman  United States
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Originally Posted by bentoronto View Post
OK, no need to go into the arithmetic of noise from pots at the far end of the chain. Just think about this: compare the natural ease and precision of twisting a knob which is perhaps at arm's length to your chair (like mine is) to fooling with a graphic interface.

(Not sure where you get 12 pot count from?)

B.
12 gangs (not necc 12 devices) total for truly balanced operation- 2 per channel. Regarding end of chain, most of my gain happens in my amp, so anything immediately preceding that will have a significant impact. If I had lower gain in my amps (which would be preferable but I'm not screwing up my NCore with my giant mitts that can't solder SMD to change gain structure) I could do things somewhat differently.

My current front end setup runs into my pre-processor (McIntosh Mx121 for source selection, HT decoding, RIAA EQ) into the Venu, so from an ergonomics standpoint, I get a knob or a remote (When I'm streaming I can also control volume from the network client, digitally, with a phone or remote).

If I'm so inclined, I can always set up the system for AES/EBU stereo input and forego HT and Vinyl functionality for that time.
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Old 11th July 2019, 09:07 PM   #69
bentoronto is offline bentoronto  Canada
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Thoughts on DSP multiamp/attenuator setup?
Quote:
Originally Posted by badman View Post
12 gangs (not necc 12 devices) total for truly balanced operation- 2 per channel....If I'm so inclined, I can always set up the system for AES/EBU stereo input and forego HT and Vinyl functionality for that time.
I went through similar contemplations so you have my complete sympathy and without me trying to second-guess your choices* except to suggest have a look at my signature below.

I presently have my Macbook Air as the centre piece. Analog sources like my golden-age Sony FM tuner go to an ADC, then into laptop via USB (although a sound-card input (if Macs had such things) or the stock Mac analog input measures perfectly good - surprise).

My Behringer DSP is fed by an inexpensive USB to AES converter, so digital right to the DSP output stage.... which makes it logical to use 4 ganged VCs.

You may vomit at the thought of having the output of a fine moving coil cartridge reduced to mere dots and dashes. Until you try it.

B.
* a bit odd you think the big gain takes place in your power amp
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Old 12th July 2019, 12:09 PM   #70
badman is offline badman  United States
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I went through similar contemplations so you have my complete sympathy and without me trying to second-guess your choices* except to suggest have a look at my signature below.

You may vomit at the thought of having the output of a fine moving coil cartridge reduced to mere dots and dashes. Until you try it.

B.
* a bit odd you think the big gain takes place in your power amp
26 dB of gain from the amplifier. Thereís dac output stage gain in the prepro of course, but I view that as the source level. I have run arrayed 1541s with no output stage, just transformer loaded, but really, isnít it best to consider fixed source gain as source level for the purposes of a setup like tuhis? Similar situation for the hdmi, lp, and all other fixed level devices (without modification).

So when I say gain, I mean that Iím running both the prepro main level at less than unity taking the dac and phono as source level before the mc attenuates/buffers, the dsp at a little more than unity in the bass, and more than unity but attenuated at amp input for the 80hz+, and then 26dB from the amp for both the bass and full range.
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