Compact amp with volume control for desktop setup

[earthtodan]

Hi all,
I'm shopping for a desktop amp to power a pair of small full range, single driver speakers, and the kicker is that it needs a volume knob (because my DX7 Pro DAC disables the volume control in line output mode ). A Topping PA3 would fit the bill nicely, but I'm turned off by the frequency response in Amir's test.

Desired specs are thusly:
- 3.5" height or less
- XLR balanced inputs preferred, RCA okay
- 20WPC is probably plenty
- Class A, A/B or D, but I want to stay away from the cheap Class D stuff
- Minimally featured. Power amp + volume.
- Under $500 preferred

Any ideas?

Dan

 

[Bob-23]

If you're able of putting together modules + ps + case + volpol, or if you have some DIYer as a friend, or if you find somewhere an already complete version of it, I can recommend an amp based on the power opamp LM1875. - For 500 $ you can get about ten of them.

I've soldered two of them, one as an amp for big speakers with the gain of 21, another one as a power headamp with the (lowest possible) gain of ten. A third kit is waiting for the winter time to be built. They are good. As they're are getting really hot, a (very) big heatsink is needed. And note: Never - even only for testing - power them on without heatsink.

Including a switch-on muting plus dc-protection circuit with relays (OmronG2R-2-DC12), based on the PC1237 chip.

Read what Rod Elliott on his great ESP has to say about LM1875:

20 Watt / Channel Stereo Power Amplifier​

Elliott Sound Products - The Audio Pages (Main Index)

DIY Audio from ESP - Audio articles, projects to build and general information about hi-fi and audio in general.

sound-au.com

(project 72)

Audiophonics offers an already soldered module for (ridiculously low) 25 Euros (which seems to be the same as the kit, available on amazon.de):

https://www.audiophonics.fr/en/amplifier-boards/stereo-amplifier-module-2-x-lm1875-2-x-20w-class-ab-p-9298.html

You need a 15-0-15V symmetrical transformer, or maximally a 18-0-18V. It gets rectified on the board.

Good luck!

EDIT: If you've never dealt with mains voltages, you should only do it with the assistance of an experienced DIYer. Note that the big caps - after having been powerd on - may contain deadly currents, and thus have to be discharged before working on the board!

 

[earthtodan]

Ah, but where is the volume knob?

I have a miniDSP 2x4+miniAMP from back in my DIY days (circa 2011), plus a DC-DC converter, but no DC power source, plus that kit doesn't have a volume knob either.

A bit of searching brought up the Burson Funk. This might fit the bill nicely.

Burson Funk | Headphone and Speaker Amp

Funk is a true-blue 45Watts per channel Class-AB. Powered by our proprietary Max Current Power Supply. Or for headphones, use it as a fully discrete, Class-A, 3Wpc. Funk is also a vastly improved Burson Fun, which won Product-of-Year on Headfonia and loved by head-Fiers since 2017.

bloomaudio.com

 

[Midwest Blade]

Gladly offer you my Emotiva A-100, it is not exactly compact has only rca connections but it does have a nice big volume control knob in the center. Send me a private message if interested and I can give you more details.

 

[sharpty]

A Topping PA3 would fit the bill nicely, but I'm turned off by the frequency response in Amir's test.

If this is what you're referring to, a +1dB boost at 90kHz is nothing to worry about. It will have no effect on the sound.

If you only need ~20W, the PA3s seems like a winner imo. Price to performance is fantastic.

EDIT: oops, I guess you actually meant the PA3, not the PA3s. The latter is quite a bit better.

 

[earthtodan]

Yep, the PA3 is a bit wonky. I didn't know about the PA3s though, and it looks just fine. Also, it's available now.

The PA3s uses TRS balanced inputs, which I've never heard of, while my DAC uses XLR line outputs. Is there any problem using XLR to TRS cables?

 

[Count Arthur]

Yep, the PA3 is a bit wonky. I didn't know about the PA3s though, and it looks just fine. Also, it's available now.

The PA3s uses TRS balanced inputs, which I've never heard of, while my DAC uses XLR line outputs. Is there any problem using XLR to TRS cables?

None whatsoever.

Page 4 | Balanced Leads

Page 4 | Professional Balanced Cables for Performers and Technicians

www.designacable.com

 

[sharpty]

The PA3s uses TRS balanced inputs, which I've never heard of, while my DAC uses XLR line outputs. Is there any problem using XLR to TRS cables?

No problem at all, they achieve the same function. Balanced 1/4" TRS I/O is pretty common on audio interfaces and studio gear.

I would avoid the Monoprice XLR/TRS cables though. They're way too heavy and use crap connectors.

 

[earthtodan]

Awesome, I ordered the Topping PA3s! Also tempted to get the Burson class A/B amp just to compare, but now I'm just getting carried away.

 

[Ears of Tin]

I have this and like it a lot.

https://www.amazon.com/S-M-S-L-Bluetooth-NJW1194-Hi-Res-Amplifier/dp/B091C9WV9Z