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Inside Yamaha amps

Let's try and stick to the topic please. Search for relevant existing threads to ask.in or create a new one for specific advice . Thanks
 
To continue the unequal warm Heat-sink issue:

Yesterday; I connected (wife's Insignia NS-B4111 CD Boombox) to the Yamaha A-S2200. I was playing music for 5 hours at 110db. The room was 59°-Fahrenheit.

I checked the temperature of the left and right heat-sinks. (they were both 88°)

I played music on the Technics SL-PD8 (compact disc player) connected to the Yamaha A-S2200 (at the same 110db volume) and the heat-sinks reached got warmer (left reached 92° and the right reached 90°).

Anyone know the reason for this?
 
GuyIsDamGood said:
To continue the unequal warm Heat-sink issue:

Yesterday; I connected (wife's Insignia NS-B4111 CD Boombox) to the Yamaha A-S2200. I was playing music for 5 hours at 110db. The room was 59°-Fahrenheit.

I checked the temperature of the left and right heat-sinks. (they were both 88°)

I played music on the Technics SL-PD8 (compact disc player) connected to the Yamaha A-S2200 (at the same 110db volume) and the heat-sinks reached got warmer (left reached 92° and the right reached 90°).

Anyone know the reason for this?
Click to expand...
Difference in the source? Measurement error?
 
GuyIsDamGood said:
To continue the unequal warm Heat-sink issue:

Yesterday; I connected (wife's Insignia NS-B4111 CD Boombox) to the Yamaha A-S2200. I was playing music for 5 hours at 110db. The room was 59°-Fahrenheit.

I checked the temperature of the left and right heat-sinks. (they were both 88°)

I played music on the Technics SL-PD8 (compact disc player) connected to the Yamaha A-S2200 (at the same 110db volume) and the heat-sinks reached got warmer (left reached 92° and the right reached 90°).

Anyone know the reason for this?
Click to expand...
Because the temps of 90 and 92 are so close the cause will be small too. It might be more signal on the hotter heatsink channel, variation in metering method, bias calibration variation, venting to each heatsink. I would meter the offset voltage and check the bias if there is a small potentiometer for recalibration then that may be done and the same goes for the offset voltage. What amp is this? I'll see if I can find a service manual.
 
Audiofire said:
Only a block diagram (based on what I can find):
Click to expand...
The A-S1200 seems to be very similar. It does have idling current and DC offset adjustments. I was able to source an A-S1200 service manual. The idling current and DC offset calibration requires probing and attaching meter clips @ the amp PCB(s) and measuring down to millivolts and a single mistake as you probe the circuit PCB will result in a fried amp module. So for the sake of interest I can email you the A-S1200 service manual for your review but I recommend you take it to a authorized Yamaha service depot for calibration. If you want the service manual private me and give me your email address.
 
I have the A-S2200 manual. Can I get the same or similar info from the manual that came with the device?
 
By the way, we can find A-S2100 "service manual" in PDF (consists of 115 pages) here.

At least for me, it is also very nice finding A-S3000 "service manual" in PDF (102 pages) here since I have been, will be, using A-S3000 in my audio rig (ref. here for the details).
 
Last edited:
I tried this:

A-S2200

(I changed the Tone Control settings to: Flat (Bass and Treble at 50%). While playing music (at 94db) in a 67° room; the Amplifier ran a bit cooler. Left heat-sink 95° and right heat-sink 92° (temperature taken after 35-minutes of music-playing).

But; I believe I've heard some distortion. I went back to the Tone Controls set to: Bass at 50% and Treble at max. I know it'll run warmer at the heat-sinks; but it'll play louder. (like many have said: "a little heat-sink warmth won't the Amplifier")

I'm basically done; with all this Amplifier stuff. (for now)



Thanks to everyone for their help and insite.
 
So I bought a Yamaha RNA1000 to replace my much more expensive tube amp in my second living room. Running 2.1 with an SVS sub and some Elac Carina bookshelves. Gotta say the amp is rock solid. HDMI is a big plus for me and really don’t need more speakers to introduce an AVR with more channels. The tube amp did have a sub out so pretty much an equal trade out but the Yamaha has room correction. Also the tube amp has 10 tubes to fiddle with. The KT88s are about $100 each and the preamp tubes not much less. The rectifiers are getting hard to find so they are up there too. Pretty happy with the change but do miss the tube glow. So I moved it to my bedroom. When I’m sick of biasing a tube amp and cost of tubes I’ll give it to my kid who thinks retro is f%caking awesome.
 
Yamaha AX-930

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I've never had the chance to listen to a pre-TopArt series Yamaha integrated. Would be great to one day A/B a nice example like this.

Thanks for sharing.
 
Mazza said:
I've never had the chance to listen to a pre-TopArt series Yamaha integrated. Would be great to one day A/B a nice example like this.
Click to expand...
I would start with the specifications, then this:
www.audiosciencereview.com

Audibility thresholds of amp and DAC measurements

Introduction A recurring theme on ASR is whether or not the various measured qualities of the devices are audible. In this post, I'll present some clear and visual thresholds for when those imperfections can be considered a potentially audible concern. I will not explain the basics of amp/DAC...
www.audiosciencereview.com www.audiosciencereview.com
 
Mazza said:
I've never had the chance to listen to a pre-TopArt series Yamaha integrated. Would be great to one day A/B a nice example like this.

Thanks for sharing.
Click to expand...
The AX-930 is a somewhat rare model, and this one is my latest project. I really love its design.

It needs some TLC work -cleaning the speaker relays, as well as the knobs and switches. I’ll be fully disassembling and thoroughly cleaning it, marking the positions of the bias potentiometers before cleaning those as well. The thermopads for the transistors will be replaced with new Sil-Pads.

In terms of sound, there’s not much difference between these amplifiers. "TopArt" was simply Yamaha’s branding for the internal component layout.

The AX-930 was essentially an evolution of the AX-900 (1986-), introducing HCA (Hyperbolic Conversion Amplification) and refinements in circuit design rather than just a cosmetic facelift. It was succeeded by the AX-1050 in 1990-91, followed by the AX-1070 and AX-1090 in the mid-'90s. I also own the AX-1090, which recently received a full servicing. Before the AX-900, there were the A-1000 (1983) and A-1020 (1985).

This entire series represented Yamaha’s high-end integrated amplifiers, all sharing a similar pedigree, power output, and low-impedance drive capability, despite their varying designs and layouts. However, the AX-930 was the first in the line to introduce HCA (Hyperbolic Conversion Amplification), a form of sliding bias.

After the AX-1090, Yamaha didn’t release another high-end integrated stereo amplifier until 2007, with the A-S2000 and A-S1000. I also owned the A-S1000.

To reiterate the blood-line:
  • Yamaha A-1000 (1982-1984)
  • Yamaha A-1020 (1984-1986)
  • Yamaha AX-900 (1986-1988)
  • Yamaha AX-930 (1990-1991)
  • Yamaha AX-1050 (1992-1994
  • Yamaha AX-1070 (1994-1995)
  • Yamaha AX-1090 (1995-1997)
 
The Yamaha AX-590.
1995-1997

I bought it defective; the seller said it only worked with CD-Direct until it failed completely. It was the filthiest amp I’ve seen, covered in layers of pet hair and nicotine residue, with resistors barely visible.
After a full teardown and cleaning boards, components and pots, I inspected components and solder joints. Everything looked fine. With a new fuse and pre-out/main-in RCAs connected, it worked perfectly. The issue must've been one of the pots in the pre-amp board and the fuse probably blew because of all the filth was shorting somewhere.

The bias is low (1.5–1 mV ~ 6.8–4.6 mA) and non-adjustable, but it sounds great.

I fixed the dents and repainted the originally titanium-colored cover in black, which, in my opinion, looks much better than the lighter shade.
I wish I had taken some before pictures so you could see the improvements.

High-quality components throughout and a Top-ART design. Its resemblance to the A-S series is clear. Despite being a mid-budget amplifier, it retains Yamaha’s signature strength -delivering substantial dynamic power into low-impedance loads effortlessly. The AX-592, which shares the same design, was measured at 460W at clipping into 2 ohms. Pushed further into 1 ohm with a 10ms signal, it reached 478W. -Anecdotal, I saw no actual measurements of this.

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@TheBatsEar will you update the OP index some time?
 
^^^^ nifty!
Beautiful, in fact. I do like that 'gunmetal' (or graphite, or whatever they might have called it) finish.
 
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