Hey, I recently purchased a cheap gemsound amplifier on ebay. It works decently however, when there is a constant noisy hiss in the background. Is this just from cheap parts used or is it faulty? The music sounds good (Not Super High Quality).
I say noisy hiss becasue its not like a regular hiss it almost sounds as if the hiss was encoded to a really low qualty Mp3 and them played back.
If this is just cheap components is there any thing i can do to reduce it of make it less noticable? (Circuitry or AC filter)?!? I'm kind of new to this topic... but fimilair with audio...
Any help would be greatly apreciated. (model number is EXA3950)
I say noisy hiss becasue its not like a regular hiss it almost sounds as if the hiss was encoded to a really low qualty Mp3 and them played back.
If this is just cheap components is there any thing i can do to reduce it of make it less noticable? (Circuitry or AC filter)?!? I'm kind of new to this topic... but fimilair with audio...
Any help would be greatly apreciated. (model number is EXA3950)
I have been doing some research on google and found some posts where people say that gemsound uses cheap (thus noisy) components.
Am i correct in assuming that, there is no resonable cheap way of fixing this?
Am i correct in assuming that, there is no resonable cheap way of fixing this?
Can anyone give me any advice on this??
Could it be as simple as adding a DC filter or perhaps a different power supply?
Could it be as simple as adding a DC filter or perhaps a different power supply?
Hi sound_prodigy,
I'm guessing no one is familiar with it. Do you have a manual or schematic. Finding one may get things started for you.
Also, do you have an oscilloscope? Does it run warm / hot? It may be oscillating.
-Chris
I'm guessing no one is familiar with it. Do you have a manual or schematic. Finding one may get things started for you.
Also, do you have an oscilloscope? Does it run warm / hot? It may be oscillating.
-Chris
no experience with them directly, but i see their stuff at radioshack all the time. a house brand, i assume.
i would start with a major power supply upgrade. how good can the PSU really be at the prices i've seen their stuff for new? not very. beef up capacitance and add some bypass caps. for upgrading typical consumer midrange stuff i just use cheap RS mylar caps and they do the job pretty effectively.
i would start with a major power supply upgrade. how good can the PSU really be at the prices i've seen their stuff for new? not very. beef up capacitance and add some bypass caps. for upgrading typical consumer midrange stuff i just use cheap RS mylar caps and they do the job pretty effectively.
I think I've read that metal film resistors are better than carbon resistors, at 0.06 cents each thats a cheap swap.
here are some pictures from within the amplifier.... the power supply looks to be extream bottom of the line.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
i don't have an osciloscope. But if the amp were oscilating wouldnt the output be weak?... I have an unrepairable marantz 510m, Missing one of the main drive chips, would the preamp or possibly the power supply from it be any use to me? I am going to check the outputs on the power transformer, but if anyone already knows what they are that would be extreamly helpful.
gemsound amp
This thing looks better then I thought it would! Looks to be a true 160 to 200 watts per channel, and probably about 350 to 400 bridged, by the outputs and transformer rateings.
Rewire the thing, get the signal line from the power lines, get read of all that AC line sitting on top of the right amp board ect....
looks like typical cheap construction, look for resistors in the low signal line that are sitting with an extra inch of lead length on the output boards, stuff like that, then look at 1% metal film in critical circuit areas, it a straight forward design no surprises.
This thing looks better then I thought it would! Looks to be a true 160 to 200 watts per channel, and probably about 350 to 400 bridged, by the outputs and transformer rateings.
Rewire the thing, get the signal line from the power lines, get read of all that AC line sitting on top of the right amp board ect....
looks like typical cheap construction, look for resistors in the low signal line that are sitting with an extra inch of lead length on the output boards, stuff like that, then look at 1% metal film in critical circuit areas, it a straight forward design no surprises.
the marantz might have some PSU parts you can take, but check the voltage rating on the caps and stuff first. it's not likely that the transformer is the right rating but you can always check.
The Marantz 510M is not unrepairable.
Don't part it out!!!! I can fix them, so can any good technician. Please don't destroy it.
-Chris
Don't part it out!!!! I can fix them, so can any good technician. Please don't destroy it.
-Chris
I would say that the Marantz is most likely far better build than the Gemsound. Here's another vote to concentrate on the former.
/Hugo 🙂
/Hugo 🙂
Hi sound_prodigy,
The technician who works on the 510 has to be a good one. Learners will only destroy it. The average TV tech will accomplish the same feat. The outputs are series - parallel.
Fix it right or sell it to someone else who will (repair it properly). I have repaired a few of them (10 or so).
-Chris
The technician who works on the 510 has to be a good one. Learners will only destroy it. The average TV tech will accomplish the same feat. The outputs are series - parallel.
Fix it right or sell it to someone else who will (repair it properly). I have repaired a few of them (10 or so).
-Chris
The marantz 510m is missing the left amp board... the right is still working for the most part... I'm willing to sell it if someone is willing to give me a good deal on it. I dont know what it's worth. Right now i think it would cost more to fix than its worth. Or if someone can repair it at a resonable price.
I inherrited the faulty amp. I wanted to see why it wasnt working so I took a look inside. There were several burnt resistors so I removed the board in hopes to find a marantz repair technition. However I never got around to it and after several moves it's no where to be found. You can only imagine my anger. The thing that sucks is that i imagine the problem had a very easy fix. Makes me angry thinking about it. I doubt theres anyway to douplicate such a vintage board.
Hi sound_prodigy,
The board could be duplicated. It might be a nightmare though. Just getting the parts that fit the board.
There is no way to repair just the PCB. I don't know any tech that would work on just the board. Try not to bring in a sub assembly ever again. Keep the unit together.
What I would do at this point is put it aside, don't rape it for parts. You may find that board in an unexpected place, or find another amp like it. Between the two you can get one working.
-Chris
The board could be duplicated. It might be a nightmare though. Just getting the parts that fit the board.
There is no way to repair just the PCB. I don't know any tech that would work on just the board. Try not to bring in a sub assembly ever again. Keep the unit together.
What I would do at this point is put it aside, don't rape it for parts. You may find that board in an unexpected place, or find another amp like it. Between the two you can get one working.
-Chris
Thanks for the advice, i think your right... the marantz is a great peice of equipment. I'll hold on to it.
....the gemsound on the otherhand... worst purchase i ever made.sound quality sucks. Ill probaly end up using it to drive subs or something where you cant hear the awful distortion in the high end.
....the gemsound on the otherhand... worst purchase i ever made.sound quality sucks. Ill probaly end up using it to drive subs or something where you cant hear the awful distortion in the high end.
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