ADCOM GFA 555se

[PENG]

It seems that we missed the point....
The issue is that one of the amps on the left Chanel raises the temperature to 42 C on low volume, the Right Chanel is 20 C and there is a slight buzz from the transformer.
On the other amp both channels are running cool 20-25 C.
They both stand at the moment one on top of the other with plenty of ventilation.
Photo shows that there is plenty of room around it.
I am asking if the bias/ dc offset has something to do with it at least for this Chanel.

It seems that we missed the point....
The issue is that one of the amps on the left Chanel raises the temperature to 42 C on low volume, the Right Chanel is 20 C and there is a slight buzz from the transformer.
On the other amp both channels are running cool 20-25 C.
They both stand at the moment one on top of the other with plenty of ventilation.
Photo shows that there is plenty of room around it.
I am asking if the bias/ dc offset has something to do with it at least for this Chanel.

I did miss your vertical bi-amp wiring diagram at the time. One point I do notice now is that if you are getting the uneven temperatures when wiring up as shown in the diagram, you have one channel powering the mid/bass driver while the other channel powering the tweeter that takes very little power. I understand if that was the reason for the uneven heat then you will get the same uneven heat on the other amp as well but you are saying that the other amp does not have the same symptoms right?

So it is highly possible that the one with the uneven heat (between L/R channels) have some quality control issues, such as the way it is connected to the heat sinks, or as you mentioned, the bias, or other reasons.

Just to be 100% certain though, I would still use a test tone instead of music to ensure both amps are getting the same input signal, and obviously in that test you should put the jumper back on the speaker terminals so both channels of the amp will be working equally hard. Again, I tend to agree with you now one of the amp has a problem, but it wouldn't hurt to do just one more test before you send it back.

If it is too much trouble to do the test tone thing, you can also do a quick test by swapping the preamp outputs to see if the symptoms would transfer one one amp to the other. If the issue remains in the same amp, then I am convinced you do have a problem, but the bias adjustment is only one of several possibilities and if you try to do anything yourself you may void the warranty.

 

[APAPAS]

PENG

Thanks for you attention
swapping the preamp outputs the symptoms remains in the same amp.
They are willing to replace the unit but i have to wait to see about shipping cost.

 

[APAPAS]

Most good Hi-Fi gear now are made in China !!!!!!

I am still wondering if i did a mistake going for an old proven design with its drawbacks, but taking in to consideration the bulletproofed GFA 545 II that I have i didnt want experimenting. I was between the Cambridge Audio 851W and the 555se but i was not willing to live with an amp that was runing really hot and with a buzzing transformer. Checking what is available to drive my B&W 805s, all available amps are made in china/Taiwan. Even respected brands... Cambridge Audio, Quat, Hegel, Musical Fidelity e.t.c
May bee after sorting this issue with my ADCOM amp, I may start looking for alternative speakers. There is a never ending .... expensive story here.

 

[PENG]

Most good Hi-Fi gear now are made in China !!!!!!

I am still wondering if i did a mistake going for an old proven design with its drawbacks, but taking in to consideration the bulletproofed GFA 545 II that I have i didnt want experimenting. I was between the Cambridge Audio 851W and the 555se but i was not willing to live with an amp that was runing really hot and with a buzzing transformer. Checking what is available to drive my B&W 805s, all available amps are made in china/Taiwan. Even respected brands... Cambridge Audio, Quat, Hegel, Musical Fidelity e.t.c
May bee after sorting this issue with my ADCOM amp, I may start looking for alternative speakers. There is a never ending .... expensive story here.

My original GFA-555 was quieter than my other four power amps, including one that costs a lot more than the Adcom I hope they will send you a new one on warranty.

 

[AcuDefTechGuy]

Most good Hi-Fi gear now are made in China !!!!!!

I am still wondering if i did a mistake going for an old proven design with its drawbacks, but taking in to consideration the bulletproofed GFA 545 II that I have i didnt want experimenting. I was between the Cambridge Audio 851W and the 555se but i was not willing to live with an amp that was runing really hot and with a buzzing transformer. Checking what is available to drive my B&W 805s, all available amps are made in china/Taiwan. Even respected brands... Cambridge Audio, Quat, Hegel, Musical Fidelity e.t.c
May bee after sorting this issue with my ADCOM amp, I may start looking for alternative speakers. There is a never ending .... expensive story here.

If you enjoy your speakers, why spend more money?

Any high quality 200WPC amp should be able to drive any B&W, Revel, or any other high-end speaker brand unless you are listening to dangerous volume level.

 

[APAPAS]

First i would like to thank PENG and AcuDefTechGuy for their very helpful comments.
Two weeks it took to get my replacement Adcom GFA 555SE from the factory. (Far East) Top... after sales service I have to admit without having to pay for anything.(No heat issues any more)

-There are multiple levels of Chinese manufacturing. At one end are factories that develop and build products they then offer to importers, attaching a brand the importer specifies. It's common among bargain-basement brands. The next level is the assembly of components sent into China by international brands. After that are processes such as that used by European, American, Japanese, in which some assembly is done in China and then items are shipped back to their Country, where the job is checked and manufacture is finished. Ultimately, a brand builds a factory in China to get total control.
Similar factories make equipment for Quad, Hegel, Cambridge audio,NAD, Marantz, Krell, Arcam, Creek, and many more to mention also speakers wearing badges as exotic as B&W,Kef, Focal, Wharfdale and even Cabasse are being made in China
It all depends on what they're being paid and how they're being monitored.

Anyway

After so many months Home auditioning and experimenting with various Hi Fi gear including new speakers (Kef LS50s, ATC SCM11) and various Amplifiers Hegel, Pathos, Rogue Audio, believe it or not I am back and happy with my ADCOM GFA 555se and my B&W 805s. Switching few times with different cables and I ended up sleeping at nights without the upgraded es not to bother me any more.

A very happy music Lover

Thanks for sharing this with me