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Stereo Amplifiers >$500 (Not Integrated)

Sylafari

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#21
Get a bigger power supply for your PC? I had chirping from my graphics card, but this went away when I went to a Platinum Seasonic 800W power supply. Of course this is a guess as I don't know any details about your setup, but google GPU chirp/noise and power supply. Maybe this is what you are hearing, not sure... My noise was coming from the PC obviously, sounds like your noise is from your speakers.
I have a mini ITX build and my PSU is a 600W Gold which is more than enough for my PC (I chart max W used at about 400). I know for a fact (or at least I hope so) the noise is coming from the PC because when I unplug the USB cable from the PC the noise disappears instantly followed by the noise reappearing the moment the USB cable is plugged in. Also the DAC doesn't even have to be on when I recreate this noise.
 

trl

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#22
Yamaha A-S2000/A-S2100 Integrated Amplifier:
- http://i.nextmedia.com.au/avhub/pdf_yamahaas2000hfnov08.pdf?128701600396577735
Probably above your desired budget, but it's 100% balanced inside and with floating ground (amp's ground is not tied up to case's ground, so lower background noise, no ground-loops possible and less distortions at full power vs. similar amps with similar power specs).
A-S1x00/S2x00/S3x00 measures the same way and is also sharing the same internal schematic, only the no. of output transistors differ and, of course, output power and PSU/transformer are more powerfull as well.
A-S1x00/S2x00/S3x0 are using Circlotron technology and are using MOSFET in output buffer (overheating cause auto-decreasing the output power, so less worry about overheating defects); also, using several linear PSUs inside and lot of reservoir caps. Also, there's included a dedicated high-quality headphone amplifier around transistors and with 10uF input cap; separate PSU for the headamp as well. Several protections inside: DC-output for speakers, thermal protection for most power bridges, transformer, output transistors for each heatsink, over-current etc. Also, firmware upgradable not only for the inside DAC (on A-Sx100 models), but also for the microcontroller that takes care of the protection circuits and the relays inside.

Yamaha A-S700/A-S701/A-S800/A-S801 Integrated Amplifier:
- http://i.nextmedia.com.au/Assets/Yamaha_AS-700_Amplifier_Review_LoRes.pdf
- https://audio.com.pl/testy/stereo/wzmacniacze-stereo/2786-yamaha-a-s801
- https://audio.com.pl/testy/stereo/odtwarzacz-cd-wzmacniacz/2676-yamaha-cd-n301-a-s701
- https://audio.com.pl/testy/stereo/odtwarzacz-cd-wzmacniacz/1510-yamaha-cd-s2100-a-s2100
A-S70x/A-S80x measure the same way and is also sharing the same internal schematic. Also https://www.audioholics.com/amplifi...1-amplifier-review/yamaha-a-s801-measurements worth a read. These amps are using BJE/bipolar transistors in output buffer and dual PSU for entire amplifier, but separate smaller PSUs for DAC, preamp etc. Like most amp in this price-range, there's no dedicated headamp inside, just couple or resistors that creates a resistive divider, connected to the 6.3mm output jack. Several protections inside: DC-output for speakers, thermal protection for most power bridges, transformer, output transistors for each heatsink, over-current etc. Also, firmware upgradable not only for the inside DAC, but also for the microcontroller that takes care of the protection circuits and the relays inside.

BTW, if you like a bit of DIY, then you could have a look over https://www.neurochrome.com/lm3886-done-right/ and how well it measures (almost 100dB between fundamental and its 2nd harmonic!). Also, https://www.neurochrome.com/product/modulus-286-2-2/ and recommended PSUs, plugs wires and case might be even better.

P.S.: I do own A-S701 and I'm enjoying it. It can push over 2x130W RMS with less than 0.1% distortions on my 4-16 Ohms speakers, that would be over 100dB in my living room, so quite powerful.
 

Krunok

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#24
I know for a fact (or at least I hope so) the noise is coming from the PC because when I unplug the USB cable from the PC the noise disappears instantly followed by the noise reappearing the moment the USB cable is plugged in. Also the DAC doesn't even have to be on when I recreate this noise.
It shouldn't be like that. IMHO it would be much better if you solve that problem at its source (within your PC) than with balanced connections between your DAC and amp.

Btw, which DAC do you have?
 
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#25
What about the micca origain?
 

amirm

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#26
Anyone know any great stereo amplifiers that measure well that are close to $1k (maybe a little more)?

Seems hard to find as most reviews are just subjective opinions backed by nothing.

The stereo amplifiers measured by Amir so far all seem to be not so great compared to the great amplifier options we have for headphones!
See the first one that does perform well at that price: https://www.audiosciencereview.com/...and-measurements-of-hypex-nc400-diy-amp.5907/
 

amirm

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#27
Amir will need a bunch of non-inductive high power dumy loads and obviously build the LPF that kills all the extraneous crap that comes out of Class D amplifiers. Someone has reverse engineered the overpriced AP one and I have a schematic someplace. Maybe I should build one for him and one for me.
I got talked into buying the AP one for $1,500 (AUX-0040). They use custom wound inductors so even with the schematic, there is work to do if you want to build yours. The one I bought has flat response to 40 kHz (and almost up to 200 kHz with not much drop) so it does include any crap that may be audible to us.
 

Krunok

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#28
Anyone know any great stereo amplifiers that measure well that are close to $1k (maybe a little more)?

Seems hard to find as most reviews are just subjective opinions backed by nothing.

The stereo amplifiers measured by Amir so far all seem to be not so great compared to the great amplifier options we have for headphones!
I thought @Blumlein 88 would recommend this one.. :cool:
 

restorer-john

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#29
I got talked into buying the AP one for $1,500 (AUX-0040). They use custom wound inductors so even with the schematic, there is work to do if you want to build yours.
Those AP guys sound like your crack dealer. :)

I first read your sentence as "custom wood inductors" and I thought AP had gone all 'audiophool' for a second.
 

Sylafari

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#31
It shouldn't be like that. IMHO it would be much better if you solve that problem at its source (within your PC) than with balanced connections between your DAC and amp.

Btw, which DAC do you have?
I have a RME ADI 2 DAC, I don't think the problem is solvable within the source as I would have to possibly buy replacement PC parts (GPU, Motherboard, PSU) and test them out each and hope the same issue doesn't occur and its possible I might even make the issue worse.

Those Yamaha amplifiers are interesting but indeed a bit out of my budget.

Those Hypex Nc400 amplifiers do look interesting, maybe if I stretch my budget I can buy 2 DIY monoblocks. Also the March Audio ones are coming out soon hopefully. Might need to patient. (Hard to be patient :( )
 

trl

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#32
[...] Those Yamaha amplifiers are interesting but indeed a bit out of my budget.
[...]
You could still give a try to the A-S701 or A-S801 amps, if the A-S1100/2100/3100 are too pricey. If you don't like the sound after 1 week of testing, just return it.

I did my purchase of the A-S701 from amazon.de and after couple of days I was thinking to return it. Reason: the bass was just not as expected, my old Pioneer A-209R had a better bass...more punchy and with a better impact. I've no idea what happened, but after 1-2 week of listening things were settled down and bass got alive. Worth mentioning that I don't believe in the burn-in crap, because I see no technical justification, but maybe I'm wrong; also, maybe my initial tests were done with the amp cold...don't know what to say, but now my A-S701 sounds perfectly well. Also, ARTA, RMAA and REW tests were completed and results are per my liking.
 
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Sylafari

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#34
Well I solved the ground noise problem by using an optical cable instead of a USB cable (all the usual popping during GPU load is gone!). My speakers still hiss a little, I feel that is because my speaker amplifier isn't very clean...

Wish the Nuforce STA 200 measurements were up before I bought them. Guess I'm still looking for a new amplifier maybe.
 
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#35
I did my purchase of the A-S701 from amazon.de and after couple of days I was thinking to return it. Reason: the bass was just not as expected, my old Pioneer A-209R had a better bass...more punchy and with a better impact.
Good to know. I really loved having the US version. Warm and clear, like most of Pioneer's 'Direct Energy MOSFET' designs, and 106 dB SNR is a good measurement considering it came out in 2004.
 
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#36
I once had a similar noise issue, with a cheap Behringer UCA 202 usb DAC connected to my old desktop PC. After a while I figured out that it was the old video card. Shortly afterwards the video card failed and was replaced. Since I also replaced the UCA 202 with an Odac, I cannot say which of the two was responsible for the disappearance of the irritating noise, but I suspect it was the new video card.
 
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#37
The Yamaha AS 501 now sells for euro 350 and is more than powerful enough (2x85 watts conservatively measured) for desktop use. It also has optical and coaxial inputs.
 

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