• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required as is 20 years of participation in forums (not all true). There are daily reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

Compact amp with volume control for desktop setup

earthtodan

Member
Forum Donor
Joined
May 29, 2021
Messages
14
Likes
10
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 :facepalm:). 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

Senior Member
Joined
Jul 3, 2019
Messages
425
Likes
369
Location
Berlin, Germany
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​

(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):
ma-lm01-inpage.jpg


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!
 
Last edited:
OP
E

earthtodan

Member
Forum Donor
Joined
May 29, 2021
Messages
14
Likes
10
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.
 

Midwest Blade

Senior Member
Joined
May 8, 2019
Messages
354
Likes
464
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

Member
Joined
Jan 11, 2019
Messages
76
Likes
92
Location
Queen City
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.
index.php


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.
 
OP
E

earthtodan

Member
Forum Donor
Joined
May 29, 2021
Messages
14
Likes
10
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

Major Contributor
Joined
Jan 10, 2020
Messages
1,289
Likes
2,621
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.

 

sharpty

Member
Joined
Jan 11, 2019
Messages
76
Likes
92
Location
Queen City
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.
 
OP
E

earthtodan

Member
Forum Donor
Joined
May 29, 2021
Messages
14
Likes
10
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.
 
Top Bottom