[mca]

I am the new owner of a used RM-200 purchased from a fellow Audiocircle member. I have noticed my speakers "ringing" while using this amp. Could this be tube "ring"? The amp is sitting on the floor between the speakers on a maple butcher block. I cant put it on my rack because I don't have the space you mention in the manual. Someone suggested trying tube dampers, any thoughts?

Also, this thing gets HOT. Not just the tubes, but the entire metal top plate. Much more so than my Response audio 3205 amp. Is this normal? I have checked bias and they are all within range.

[miklorsmith]

We could try the amp at my place to see what it sounds like there.   

Not this w/e though, I'm at Whistler through Monday (gratuitous brag).

[mca]

I'll take you up on that when you are back. Are you biking there?

[miklorsmith]

Yep, one day at the North Shore and two at the bike park.  There will be plenty of opportunities for bodily damage.

[Roger A. Modjeski]

Hello Music Reference owners, old and new.

Just a few things to help me answer your questions more accurately and easily. If you mention another product in your question please provide some information on that product. It is important for me to know the tube complement, power rating, bias level and any other information that pertains to your question.

For power questions you listening level (in dB) is essential. For noise questions your speaker sensitivity and distance from it are important. For preamp to power amp drive concerns I will need to know the output impedance of the preamp.

Roger

[Roger A. Modjeski]

I am the new owner of a used RM-200 purchased from a fellow Audiocircle member. I have noticed my speakers "ringing" while using this amp. Could this be tube "ring"? The amp is sitting on the floor between the speakers on a maple butcher block. I cant put it on my rack because I don't have the space you mention in the manual. Someone suggested trying tube dampers, any thoughts?

Also, this thing gets HOT. Not just the tubes, but the entire metal top plate. Much more so than my Response audio 3205 amp. Is this normal? I have checked bias and they are all within range.

As to the ringing I need more information. What happens with the volume all the way down on your preamp? What frequency and level is the ringing? How far is the amp from the closest speaker? What part of the space  requirements are you short on?

From what I can tell the 3205 amp was lower in power. The RM-200 runs very cool for a 200 watt amplifier, but keep in mind amplifier power dissipation goes along with output power.

Roger

[mca]

I don't use a preamp, just the digital volume control on my Squeezebox. When the volume is down, all is fine. The ringing starts at about mid volume and gets worse as the volume is raised. It is a very high frequency ring heard through the speakers. The amp is centered between the speakers in front of my rack, there is about 3' on each side of the amp to the speakers. I don't have the 2' height above the amp in my rack. The top glass shelf is only about 8" from the top of the amp.

The 3205 only puts out 60wpc and has been the largest tube amp I have owner thus far. I guess I'm just not used to the heat a larger amp puts out.

Oh yeah, as for tubes, the KT-88's are Gold Lion reissue while the 6BQ7 drivers are stock. Maybe it's time to replace the driver tubes?

[Roger A. Modjeski]

Go ahead and tap on the amplifier transformer cover with the volume set to zero. Tell me what you hear.

Since the ring rises with the volume setting it would appear to be coming from your source.

8 inches above the amplifier is adequate if the sides are not blocked off.

There should not be a big difference in heat. In this case imagine your old amp as a 100 watt light bulb in the space that contains it then imagine two such bulbs in the same space. From a thermodynamic point of view the temperature rise would be twice as much. Keep in mind that we become very temperature sensitive above 100 degrees F and 150 degrees is about as hot as something can be and keep your hand on it. Being that our experience of temperate is not linear it doesn't take much when you get in that upper range. I am testing the new EM7 power transformer today and it tops out at 138 F after being on for 3 hours. At one hour its only 102 which feels a lot cooler. The change from starting temp at 74 to 102 (28 degrees) feels like a very small change. The change from 102 to 117 degrees feels like a lot more but is only 15 degrees.

I have been looking at common transformer specs lately and find the rise at full load to be 40 degrees C that's 72 F. Added to room temp gets you to 147 which feels quite hot.