Help needed resolving Amplifier issue!

[bcan]

Hi all,
I'm hoping to get some advice solving a mystery with sporadic amp performance... I'm using a very nice Spectron Musician amplifier - 500 watts x 2 with PSB Gold i speakers, Denon 2900 CDP and a Promitheus Audio passive preamp. Also use a Panamax 5300 power conditioner and the Spectron is plugged directly into the wall, not the Panamax. Generally I'm very happy with my "working mans" 2-channel system. But periodically my right speaker works only very faintly where I barely get any sound - but I do hear very soft music - about 10% of the volume of the other speaker. If I continue to play music for an hour or so the problem goes away and all is good. This happens every few weeks and I can't figure it out. I've troubleshot/isolated the problem to the right channel of my Spectron amp (it's not the source cd player, speaker, speaker cable or ic cables, so I am deducing it is the amp). My Spectron is under warranty - I sent it in for repair and they could not find any problems with the amp. I did not have this problem again after receiving the amp back from Spectron (about a month ago now) until today. Any thoughts or suggestions as to the problem and how to fix it?

Many thanks!

[dakatabg]

O man I don't know what to tell you! If it is something inside the amp try the connectors! If it is not the connectors there is nothing else you can do! Could be a defect in the amp! If you turn it on and if you play it for hours and it starts working good that means something has to warm up inside before you get the music going!

[blackraven]

Are you sure its the amp and not the CDP or pre amp. Try a different source and preamp if possible.

[harley .guy07]

If this problem is starting to come back then I would check every available source for this problem. Cables, Ac power, preamp, cdp. Any source for the problem outside the amp. Once you have done that and you still can't find the problem I would get back on the phone with spectron and tell them that the problem has come back and see if you can send it in again and they spend some time with it to make sure they did not miss something. Some times companies will put equipment of test benches and test them for short periods of time and miss the problem because they don't run the component long enough for the problem to show itself. The problem could be in the thermal protection circuit in the amp and the problem won't show up until it gets to a certain temperature or it could be one of the other protection circuits kicking in prematurely or at the wrongg time. I had a Bass head(I am a bass player) that would click off at high volumes and come to find out the first generations of this head had a triac transister that was part of the clipping protection circuit that was way to sensitive and after this transistor was taken out then the head worked perfectly. I am not saying that this is your problem but it could be in the protection circuits since they usually control output of the amplifier. Do some testing yourself and see if you can't figure it out. Play your amp for a while and let it warm up and see if it only happens at higher temperatures. Or does it happen at higher output levels. there is also a very slight possibility that your speaker has a short in it or a crossover component is damaged causing a short and making the amps protection circuit kick in. I would take everthing into concideration in your system before sending the amp back in so that the company will know its in their amp and spend more time with it to see what is wrong with it. Good luck!!

[harley .guy07]

I did some research on Spectron and they only make digital amps. I have not worked with digital designs myself except with plate amps for subwoofers and car amps I do know that the music signal is digitized when it enters the amp or at least from my understanding of how they work and that is part of why they are more effecient. I am forced to wonder if there could be something in the digital process that could cause this problem as well. Just a thought.

[manlystanley]

>But periodically my right speaker works only very faintly where I barely get any sound - but I do hear very soft music - about 10% of the volume of the other speaker.

Oh man, does this sound familiar. My HK has this real bad. But, with mine it occurs much more frequently. It turned out to be the integrated/separate button on the H/K integrated amp. Since I only now run the H/K as a power amp the problem is much less (but still does occur sometimes.). When it occurs I just flick the pushin button 50 times and it works better. I'll need to upgrade the H/K sometime.

Try this:

-- Move the balance knob to the side that the problem occurs on (e.g. right side). (So that you can hear it when the sound stage collapses).

-- Then start wiggling cables, buttons, etc.

-- It sounds like it heat sensitive. When it get's warmer the problem disappears. So do this at the start of a listening session.


Hope this helps.

Best Regards,
Stan

[Jim Eck]

>But periodically my right speaker works only very faintly where I barely get any sound - but I do hear very soft music - about 10% of the volume of the other speaker.

Oh man, does this sound familiar. My HK has this real bad. But, with mine it occurs much more frequently. It turned out to be the integrated/separate button on the H/K integrated amp. Since I only now run the H/K as a power amp the problem is much less (but still does occur sometimes.). When it occurs I just flick the pushin button 50 times and it works better. I'll need to upgrade the H/K sometime.

Try this:

-- Move the balance knob to the side that the problem occurs on (e.g. right side). (So that you can hear it when the sound stage collapses).

-- Then start wiggling cables, buttons, etc.

-- It sounds like it heat sensitive. When it get's warmer the problem disappears. So do this at the start of a listening session.


Hope this helps.

Best Regards,
Stan


If you find that wiggling or turning the knobs improves the output, or if you hear scatchy sounds when operating any controls or dropping out when used or come back, get a good contact cleaner, I use DeOxit 5, you will need to get to the inside of the contact or potentiometer that is the issue, (after unplugging the amp) get under the hood, spray the inside of each pot and or switch and then work what ever control you are cleaning through its full range of operation several times, while you are inside clean all pots and contactors/switches. I have repaired more amps with this than any other thing, dirty controls will contribute static and intermittant sound more times than anything. Cleaning the rca plugs and any jumpers will also improve them.

This really sounds like the issue with the HK, when you work the contol back and forth you are cleaning it, however not enough, it needs the contact cleaner, and you still may need to repeat once or twice.

Good luck, let us know.

Keep em spinning, Jim

[Jim Eck]

Research checking the DC offset and then check this but I would think they would have done this while they had it at the service station. It is a simple procedure, you will need a multimeter.

Jim