Dayton Audio DSP-408

[gigantic]

Coming back to this, I'm now using it to multi-amp the LaScala clones in my profile pic, with a pair of Alesis RA-150 bridged mono blocks driving JBL 2225H woofers, a 15WPC Glow Audio Amp Two on the mid horns, a pair of PRV Audio WG45-50 w/ PRV D2200PH drivers and a couple Schiit Audio Rekkr mono blocks on the tweeters, Machined Audio Horn Lens L-MAHL & B&C DE10 drivers with a combined sensitivity around 105dB. I'm quite happy with the functionality of the DSP-408, particularly the PEQ and time alignment, which have really allowed me to dial in the response of the speakers, from:

to +/- 3dB from 23Hz to 20kHz:

I suppose I can live with the mediocre ADC performance and relatively mild distortion, but one thing I'm finding difficult to live with is the ever present hum coming from the unit. it's relatively low-level and can really only hear it when music isn't playing, and the amplitude doesn't seem to vary with input voltage, but it's annoying just the same. I'm pretty sure it's coming from the cheap wall-wart that was shipped with it. Have any of you had acceptable results with an upgraded PSU? I'd really like to make this perform better, but I'm also considering throwing in the towel and opting for a professional unit, but I'm a bit in the woods in finding one with similar features for PEQ and time alignment; (the marketing/documentation on many of the ones I'm finding are not particularly good or thorough)

 

[xrk971]

I recall the factory remote control volume knob causes an audible hum. It’s for a microcontroller and shaft encoder knob - the circuit generates noise if plugged in. Are you using that?

It’s been a while since I used mine but don’t recall it was the PSU. However, if it’s 12v, there are a lot of pretty quiet 12v 1A ones (SMPS but quiet). I have had reasonable luck similar to this one for preamp duties. Exact one not available anymore but looks like it.

 

[gigantic]

I'm not using the remote. I've been able to mitigate it since I've first posted by reducing the input and output gain and giving more headroom to my mid and bass amps. The noise is still there, but it is barely discernible. I may pick up an isolated transformer, but for the time being, I'm exploring pro DSP options with balanced connections, but the trick will be finding a pro unit that matches or improves the functionality of the Dayton, while reducing noise and improving sample rate. I'm currently using almost every available bit (admittedly more than is probably necessary) of parametric EQ to tweak and flatten the response of my LaScala clones and it's a crutch that I'd rather not go without.

 

[xrk971]

The ADAU-1452 eval board from AD works well and has a lot of I/O options (optical, I2S, SPI, and analog). Program using free Sigma Pro DSP suite. It has 8 single ended channels or 4 balanced.

https://www.digikey.com/en/products/detail/analog-devices-inc./EVAL-ADAU1452REVBZ/9809249?utm_adgroup=&utm_source=google&utm_medium=cpc&utm_campaign=PMax Shopping_Product_Low ROAS Categories&utm_term=&utm_content=&utm_id=go_cmp-20243063506_adg-_ad-__dev-c_ext-_prd-9809249_sig-Cj0KCQiAwbitBhDIARIsABfFYIJWoE-ivPIN3Y6dB0T1Cym2gpIrxrleqUrqUVScZa4VJoNA4QdYZL0aApC5EALw_wcB&gad_source=1&gclid=Cj0KCQiAwbitBhDIARIsABfFYIJWoE-ivPIN3Y6dB0T1Cym2gpIrxrleqUrqUVScZa4VJoNA4QdYZL0aApC5EALw_wcB

I think the latest variant is this one but I have not personally used this one:
https://www.mouser.com/ProductDetail/Analog-Devices/EVAL-ADAU1467Z?qs=BZBei1rCqCCDsBku5vHNkw==&mgh=1&gad_source=1&gclid=Cj0KCQiAwbitBhDIARIsABfFYII8Ta5IlhxExVlFWeh0ijPx9zPj2F4nY_hokzkitDu_1T_H1L6xfQ8aAtnWEALw_wcB

 

[gigantic]

That's fascinating, but way above my pay grade. While I've built computers from parts, re-engineered speakers, built crossovers and modded amps, doing a DSP crossover from a board like that may be beyond the limits of both my skills and patience. Ideally, I'd want something a bit more plug and play, with at least a pair of balanced ins and a minimum of 6 balanced out. I've only been doing this a little over a year...

 

[wafflesomd]

I just got one and the noise overall seems a tad on the high side. Hum is there. Gonna try some other power supplies and see if that helps. I only got to toy with it for a bit and of course, easy filtering. I'm going to go more in depth tomorrow, but at the moment I find the noise pushing me towards a passive xover.

Quick question, why is that directly hooking up a tweeter with active filtering seems to have a lot more noise than having passive components in line? Do the resistors or cap maybe act as some sort of noise sink?

 

[xrk971]

Passive components by their nature, don’t add noise. Except at very low signal levels, where you may have things like Johnson (thermal) noise in resistors - but that’s very low relative to the noise you are hearing. Active circuits use opamps which have 20 to 30 transistors each. There are low noise opamps but they are more expensive. Active filters also use DSP sometimes so you are talking about taking the signal from analog to digital in a ADC then processing/filtering it, then a DAC again.

I also prefer passive crossovers for ultimate low noise speaker systems.

 

[wafflesomd]

Tried a different PSU, no noise change. But also I ran the amp with no input and same noise so I suppose the unit is not really adding any noise to that amp and driver combo. The woofer seems to have a bit more noise than before though.

Passive might be a better option for me, I've gotten pretty used to the quiet of my passive towers, just so much more work to measure these things for passive integration.

 

[wafflesomd]

This unit just doesn't want to play nice with my crown xli800, ground loops everywhere. Amp seems to register some sort of constant signal but I don't hear anything. I'd argue what I'm hearing doesn't sound as good as filtering done in EQ APO. I speculate it's because I'm running into another ADC/DAC in the Dayton. Same problem I had with minidsp, just kinda kills something about the sound stage and dynamics that I could never put a finger on, but your brain just knows something isn't right.

 

[wafflesomd]

Oh man, I had to update the thread this one. Don't know if anyone would believe me unless I showed them on a recording because it sounds silly.

I was toying with cabling and listening to the woofer, when I set the unit down on floor and let it kinda fall over a short distance to lean on my entertainment center. It made for a knock similar to a tap from your knuckle. That tap caused the unit to hum and then dissipate. Reminded me of a spring reverb. But yeah you can tap it with your knuckle and it will hum with it.

 

[CyberPit]

I suppose I can live with the mediocre ADC performance and relatively mild distortion, but one thing I'm finding difficult to live with is the ever present hum coming from the unit. it's relatively low-level and can really only hear it when music isn't playing, and the amplitude doesn't seem to vary with input voltage, but it's annoying just the same. I'm pretty sure it's coming from the cheap wall-wart that was shipped with it. Have any of you had acceptable results with an upgraded PSU?

I guess the hum-noise might not coming from the mains. I also have DSP-408, here is the remaining noise spectrum.

This is the same measurement but the Wired Remote is connected

The frequency of hum-like-noise is different from the mains supply (my place is 50Hz)
This 158.9Hz-based noise was gone if I disconnected the remote unit.

You'd better disconnect the Remote Control Unit if you are using it.

CyberPit

 

[gigantic]

I've since made some changes to my system. I've replaced the amps driving my woofers and tweeters, 5a pair of Alesis RA150 mono blocks and an Emotiva Bas-X a100, respectively, with a quartet of Fosi Audio ZA3 mono blocks. The hum persisted and was most present in the tweeters. Getting the gain staging right, improved, but did not eliminate the noise. I swapped the Dayton Audio DSP-408 with a Thomann T. Racks DSP-408 and after disconnecting the cooling fan, my system is utterly quiet. I'll likely be selling the Dayton unit, shortly.

 

[wafflesomd]

Good news about the tracks, the 206 would be plenty for me.

 

[wafflesomd]

Passive components by their nature, don’t add noise. Except at very low signal levels, where you may have things like Johnson (thermal) noise in resistors - but that’s very low relative to the noise you are hearing. Active circuits use opamps which have 20 to 30 transistors each. There are low noise opamps but they are more expensive. Active filters also use DSP sometimes so you are talking about taking the signal from analog to digital in a ADC then processing/filtering it, then a DAC again.

I also prefer passive crossovers for ultimate low noise speaker systems.

I know passive doesn't inherently add any noise, what I meant was, if I hook up say the Amiga (Paul C) speaker to an Aiyima A07, there is basically no noise at all. But if I hook up that amp to just the tweeter, there's a lot of noise. Is it just because the tweeter is padded down, thus bringing the noise down with it?

 

[Markw4]

...passive doesn't inherently add any noise...

Maybe better not to simplify things quite to that extreme. There is such a thing a current noise, excess noise, etc. Such can be a property of passive components which can then be significant in some circuits. If you like I could attach some references on the subject.