[msm_1]

Hi

I just got home and there was a msg left from a place that is fixing one of my Rogue 88 Tube amps ( using them on Apogees )
The msg said that they are 99% complete and had to replace 6 transistors, do a complete retube and critical coupling caps upgraded.

Not being a tech person I was wondering...What would be the critical coupling caps ? and does this really effect the overall sound?

They said that there is a very slight hum on the right channel and would prob cost me another $1000cdn to fix, and depending on the efficiency of my speakers I may not even hear it.

Any input is appreciated

Thanks

Mike

[blownrx7]

Replacing coupling caps would DEFINITELY affect the sound. They are directly in the signal path. 
They should be consulting with you as to what was there in the first place and what they propose to replace it with.
Beware of paying for "sideways improvement". Many are fooled into thinking different is better...
 
1000cdn sounds like replacing a transformer or two - WAY too pricey.

You should also check with Rogue, if you haven't already. They have an upgrade plan for your amp - not saying it is the way to go, but it is an option
If you want to upgrade, you may do better economically and sonically by stepping up the Rogue line on the used market -just another option.
HTH

[raindance]

Ask them to define "upgraded" for the caps. Sounds like a ripoff to me.

Where did they put the 6 transistors in a tube amp?

Hum is usually due to bias mismatch between push-pull pairs in a channel, or there needs to be some hum balancing circuitry installed. Either way, I don't see ANY need to spend $1,000, especially if it is slight...

I'd suggest sending it to Rogue next time.

[Delacroix]

I agree that asking you to pay $1000 to fix a hum that may or may not be audible in your system sounds like a bizarre proposition. I presume this is a reputable shop you are dealing with but I'd want to know exactly what they are planning to do before proceeding, and I would definitely speak with Rogue for guidance.

[JackD201]

Replacing coupling caps would DEFINITELY affect the sound. They are directly in the signal path. 
They should be consulting with you as to what was there in the first place and what they propose to replace it with.

Exactly so. Changes in coupling caps can be quite huge. They could go as far as altering the character of an amplifier depending on the circuit. The choice of coupling caps is one not to be taken lightly. As RX7 says different isn't always better. If you like your Rogue as is, then I suggest using what Rogue spent lots of time deciding on.