ELECA EAA-60 Solid State Amp- Low output/volume. Thoughts please.

[BStringThumper]

Help please. I have an ELECA EAA-60 Solid State Amp with low output/volume. It's not the typical really low volume problem, it makes it to about 60% of what we think it should. This amp has worked this way since new. (long story) It's a two channel unit, both channels perform the same. All controls work. It just doesn't put out enough sound. The op-amps are 4558s, power to the op-amps are +-14.68 VDC. The output transistors have been removed and tested, both are good. Supply rails are +-34.68V. Any thoughts would be greatly appreciated. Thanks.

[olddawg]

Have you put a 1 khz sine wave in the input to maximum output then calculated the output power in watts?

[Enzo]

Have you tried different speakers?

I can't find a rear photo, are there any jacks back there, like power amp in, or preamp out or effects loops?

[BStringThumper]

Good morning, Olddawg & Enzo. I don't have a 1 khz generator. I've been troubleshooting/repairing with a volt meter, cd player, and signal tracer.
Enzo, I did try another speaker, same low volume. There are no input/output jacks on the back of the chassis. It just has wires coming from the bottom of the chassis going to the speakers. This amp has been this way since new, it could easily have the wrong components somewhere on the board, but I can't find a schematic to check it over. Possibly just the wrong wattage output transistors???? Any thought, please? Thanks.

[J M Fahey]

It sounds to me it simply isn't as loud as what you expected, nothing worse.
Inefficient speakers will not help either.
For 1KHz generator, google and download the equivalent MP3.
Any run of the mill players supplies around 200mV on its headphone output.
400 Hz will be even better.
Raise the volume until the flute type sound becomes buzzier, then lower it very slightly until it cleans again.
You have found the highest undistorted power without a scope.
Measure AC volts (probably on the 20VAC scale) .
If over scale, go to the 200VAC one.
Power is V squared divided by impedance.

EDIT: I googled it.

It's not the typical really low volume problem, it makes it to about 60% of what we think it should.

Maybe what you think it should is not that realistic.
Sorry.

[BStringThumper]

Hi JM. Thanks for the reply. I downloaded the audio file. Thanks for the tip, it worked great! You nailed it, my cd player put out 200mv. I injected the signal. I didn't grab my dummy speaker load, I covered the speaker and put my ear plugs in. I cranked the gain and volume full up. The speaker was reading 31.3Vac., squared 979.69 divided into 8 = 122.46............... this unit has the additional 8 ohm speaker, which was not hooked up, if in parallel (16 ohms) I get 61.23 watts. This is a 60 watt amp, but we had another one to compare it to and it's quieter. If the speakers were wired wrong it would be 4 ohms and 244 watts. Please correct any errors in my math. Maybe that's the way it's supposed to be???? I don't have the schematic. Thanks again for the tip, very neat trick.

[J M Fahey]

Fine.
Your amp *does* have 60W then, no surprises there.
Now, the *big* factor is speaker efficiency.
Hi Fi speakers (as probably used there, since it's an *acoustic* guitar amp), trade efficiency for quality.

[BStringThumper]

I understand what you are saying, thank you. I need to clarify that this amp was tested against the same exact type of amp, this one is quieter. Unfortunately I was not there to see what speakers were used or what ohms. We "assume" they were the same. These were both new amps from ELECA. The test amp has since been sold. Maybe the ELECA factory put the wrong speakers in this unit? We tested it with a different speaker, as Enzo suggested, and it was still low.
Is there any way to tell what impedance it's designed to run at? It does not say anywhere on the chassis. Two 8 ohm speakers in series or parallel??? Thank you for your help.

[BStringThumper]

CONCLUSION- I talked with the people at ELECA, very nice people, very helpful. Just as JM Fahey stated, the amp is working perfectly, just not what I/we expected. The amp sounds great. So basically "It's hard to fix something that isn't broken" Thank you to JM Fahey, Enzo and Olddawg for their assistance.