Any info on Yamaha A-30D?

tthoms

Member
I picked up an A-30D, and it is an interesting beast. I wish I could get a hold of an owner's manual.

The sound is decent. Supposedly, it's a 100 watt amp, but the "output level" never seems to exceed 8 watts/8ohms even at a dial setting of "8". On the loudness slider "10" seems to be no adjustment, and "0" is max.

Any clues to it's mysteries?

Is there anything I should do in maintenance to help it shine? Mods to improve it?
 
The output level will depend upon the input level and the amplifier's gain and the 'taper' of its volume control attenuator potentiometer. If you use a source with higher output voltage, you may be able to get more power out -- but whether you need it or not will depend on your speakers' sensitivity, your room, the source material (music) and your ears.

It's worth noting that the power output meters (which I assume your amp has) are typically voltmeters; they measure the output voltage level and "do the math" to convert volts to watts according to Ohm's Law and assuming a fixed load impedance (typically 8 ohms). The power level measured by the meters isn't accurate in any real sense unless the amp is driving a load of fixed impedance (e.g., an 8 ohm power resistor). Even then, the meter may not measure "true RMS" AC voltage, so it's best viewed as a light show, or at best an index of the output level. These meters are basically useless except as cosmetic adornment.

The loudness control function you describe sounds like the traditional Yamaha variable loudness, EDIT but calibrated backwards relative to most Yamaha variable loudness controls (see image below). The idea is to set the volume control to your maximum listening level, then use the loudness control to turn the sound level down as needed. The Yamaha loudness control approximates the Fletcher-Munson loudness perception curves, so that the apparent frequency balance is maintained as the sound output level is decreased. Many, many Yamaha hifi products featured this -- as, by the way, did numerous hifi manufacturers in the 1950s and early 1960s (EICO and Sherwood, to name two examples).

YamahaCR-2020loudnesscurves by Mark Hardy, on Flickr
 
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Thank you for the explanation! So, if I understood that right, set the "volume" to the max level, and use the "loudness" to control the perceived volume.

I'm going to try that, and see what the listening experience is like.
 
That's generally the way the Yamahas work - the loudness control is a "turn down" control in their typical implementation.

I don't have any info on the specific amplifier model in this thread, however -- maybe someone does?

EDIT: Is this it? umm....

http://www.hifiengine.com/gallery/images/yamaha-a-30d-power-amplifier.shtml

YAMAHA%20A-30D%20POWER%20AMPLIFIER.preview.jpg
 
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I think it's a cool looking amplifier. I have no problem with 80's designs especially if they can back it up with some power. Hopefully the sliders behave and don't become a pain to keep from crackling all the time.
 
Thank you for the explanation! So, if I understood that right, set the "volume" to the max level, and use the "loudness" to control the perceived volume.

I'm going to try that, and see what the listening experience is like.

Sorta.

Typically you'd start with the volume and loudness both at zero. Then, turn up the volume until you're at the loudest you'd usually go. Once you have the max dialed in, then use the loudness control as the volume adjustment.

Maybe it's just semantics and that's what you're saying, but wanted to be clear that volume "at max" doesn't necessarily imply WFO/maximum possible of the adjustment range. It means the max of desired listening level.
 
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I think it's a cool looking amplifier. I have no problem with 80's designs especially if they can back it up with some power. Hopefully the sliders behave and don't become a pain to keep from crackling all the time.

Sliders seem well-behaved. So far so good!
 
Sorta.

Typically you'd start with the volume and loudness both at zero. Then, turn up the volume until you're at the loudest you'd usually go. Once you have the max dialed in, then use the loudness control as the volume adjustment.

Maybe it's just semantics and that's what you're saying, but wanted to be clear that volume "at max" doesn't necessarily imply WFO/maximum possible of the adjustment range. It means the max of desired listening level.

Thanks! That was my understanding, although I appreciate the clarification.
 
I know that this is an old thread, but one thing not mentioned is the adjustable EQ. It can be set for 7 band, 5 band or just bass and treble. Found this a neat feature when testing before listing on eBay.
 
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