Audiophile options for a HQ external USB DAC

If you're interested in something with advanced design, this Topping A-90 discrete sits at the opposite end of the spectrum to the simple quad op-amp design of the little canford amp I've got here. This is just to give an idea of how sophisticated headphone amps can get. You will pay a lot for it of course :). I have to say, this does look like a very nice amp.

www.audiosciencereview.com

Topping A90 Discrete (A90D) - Teardown and personal thoughts

I found not many teardowns with this model, especially with the output transistors uncovered and with surrounding close-ups, so I decided to purchase one for myself (second hand) to pair it with my D90 MQA then write an article here on ASR. Looks like taking the PCB out from the case if somehow...
www.audiosciencereview.com www.audiosciencereview.com
 
blackbird9 said:
If you're interested in something with advanced design, this Topping A-90 discrete sits at the opposite end of the spectrum from the simple quad op-amp design of the little canford amp I've got here. This is just to give an idea of how sophisticated headphone amps can get. You will pay a lot for it of course :). I have to say, this does look like a very nice amp.

www.audiosciencereview.com

Topping A90 Discrete (A90D) - Teardown and personal thoughts

I found not many teardowns with this model, especially with the output transistors uncovered and with surrounding close-ups, so I decided to purchase one for myself (second hand) to pair it with my D90 MQA then write an article here on ASR. Looks like taking the PCB out from the case if somehow...
www.audiosciencereview.com www.audiosciencereview.com
Click to expand...

That's a nice unit (and teardown).
 
Yes, ASR has some quality content.

I think that Topping amp would be somewhere near the current state of the art, looking at the measured performance he got, the build quality and the features they added. The op-amp version of the A90 gives the same measurements, but they added some nice upscale features to the 'D' version (covered in the 'pros and cons') section and the review conclusions. The only thing I don't like is the main-pcb mounted headphone jack sockets, I prefer headphone sockets to be mounted on daughter boards so that the sockets can be easily replaced when they inevitably break from having the jack plugs pushed in and out repeatedly; but for a home unit this is probably less important.

For anyone interested in making their own, Doug Self's website is of course one of the best resources in the world: http://douglas-self.com/
- though I wish he would update it to https!

And his book "Small signal audio design" is really the business (available on amazon, etc)

Small Signal Audio Design: 4th edition

The Douglas Self Site, audio amplifiers, Small Signal Audio Design
douglas-self.com

Another good book (that unlike the Self book is free!) is the natsemi audio book from 1977, admittedly this is now out of date, but it covers a lot of good ground.

archive.org

National Semiconductor Audio Handbook 1977 : National Semiconductor Corporation : Free Download, Borrow, and Streaming : Internet Archive

National Semiconductor - Audio Handbook 1977
archive.org
 
Just a bog-standard 3.5mm stereo cable... don't need anything special. On the one I've got the input is stereo 3.5mm jack, so I use one like this.

www.ebay.com

AUX Headphone 3.5mm Cable Male to Male Car Stereo Audio Cord Headphone PC Car | eBay

Model Number: Baseus M30 Stereo Audio Aux Cable. Style: 3.5mm Stereo Audio Aux Cable. Type: AUX Cables. Connector A: AUX. Connector B: AUX. Type: 3.5mm male-to-male Aux Cable. This cable is a great solution to protect your 3.5mm aux port from repeat pluging and unpluging.
www.ebay.com

Or if your headphone amp has 1/4" jack or 2 phonos, then you need the appropriate cable. Doesn't need to be anything expensive. It might be worth paying a little more for gold plated connectors, but I wouldn't worry about anyting like OFC cable or the other nonsense. The cable I'm using right doesn't even have gold plated plugs.
 
One more tip, if you're connecting the headphone output of the thinkpad into the line input of the headphone amp, then I would keep the master volume on the thinkpad fairly low, say 30%, and turn up the volume on the headphone amp itself, to avoid clipping in the headphone amp input stage. At least try that to start with. Let the headphone amp do it's job rather than feeding it with too high an input signal. You can then experiment with increasing the output of the pc's headphone socket.

Of course if you're connecting the line output of the PC into the headphone amp then this isn't an issue.
 
I checked the price of that Topping amp, it's ridiculously expensive IMHO. I would certainly want to listen to it and compare to other types before shelling out that kind of money on a headphone amp. The measurements ASR got in the review are very good, but whether that would actually sound any better listening to music, I don't know. I suspect the law of diminishing returns very much applies.
 
This looks like an interesting project for anyone who wants to try making one, and pretty low cost too. The concept is based on Doug Self's parallel 5532 investigations. He's got some very good reviews, FWIW.

www.diyrecordingequipment.com

HC1 High Current Headphone Amp

The HC1 is an expandable, high-powered headphone amp designed specifically for critical studio monitoring. The HC1's circuit employs parallel amp stages for greater power and lower distortion. This parallel-opamp concept has been known in theory for decades and was put to practical use in...
www.diyrecordingequipment.com www.diyrecordingequipment.com

He's done a video giving an intro to the HC1.

View: https://www.youtube.com/watch?v=qU4i7Pd2PRE


Another place well worth a look is elektor magazine, they always used to publish high quality audio designs and provided a custom PCB service.
It appears they are still in business here: https://www.elektormagazine.com/magazine . It looks like you have to register to read their stuff. If you search archive.org you can find back-issues though, a lot of their older designs will still give excellent performance. Whether you can still get the pcb's from them is another question.
 
Elektor headphone amp kit. This is an all-discrete design (no IC's). Spec looks very good, THD+noise < 0.005% @ 1 kHz (five parts per thousand, which is excellent).
Uses standard widely available transistors and they have a PCB for it. The designs they publish are usually excellent. Definitely worth a look.

www.elektormagazine.com

Low-cost Headphone Amp

There have of course been numerous designs for headphone amplifiers before this one, either more or less successful and simpler or more elaborate. The design presented in this article is straightforward, sounds quite good and can be built using well-established components.
www.elektormagazine.com www.elektormagazine.com
 
You must log in or register to reply here.
Back
Top