C-26 loudness control

I decided to hook up mt C-26 yesterday and give it a whirl with another system and now the loudness control is screwy. If it is flat it works fine but when I try increase it the sound starts to diminish and becomes very faint, even at higher volume levels. It does sound a bit scratchy as I raise the loudness level. Can it be something as simple as a dirty pot? Should I deox and see what happens, or do you think it is something more serious/technical.:scratch2: Have a good one.

What diminishes? I'm not sure what the problem is. The loudness control on that pre is intended to add more EQ when the volume knob is turned down and reduce it as you increase volume.

Or is something else whacky?

Off the top of my head the way you use the loudness control is to leave your master volume control at the desired normal listening level. Then advance the loudness control which subtracts the lower midrange, midrange and highs to a comfortable background listening level with the bass being elevated to correct for the ears loss in sensitivity. This assumes you have calibrated your amp and speakers to the C-26. How do you do that? You set the volume control to between 12 and 1:00 o'clock and advance the volume controls on the power amp to a level just above what is comfortable for you in your listening space. Once that is done the loudness control will track properly with the master control set at 12:00 o'clock. Go to hifi manuals.com and down load the owners manual for all the details.

Somethings different. Maybe it's because I am running the MC-206 which does not have gain controls like the MC-250's. If I have the volume on the pre set at 12:00 and I try to increase the loudness the sound will diminish. I could try increasing the volume on the pre more and then increasing the loudness tonight when I get home. Normally if I increase the loudness It would increase bass and smooth out the highs. For some reason it is almost as if the volume is being turned down when I increase the loudness. IDK? Maybe I'll hook the MC-250's back up and see if it makes a difference. I have a C-28 too. I can try that. It is stepped loudness though. Thanks.

You guys made me pullout the schematic......the loudness control is in series with the volume and balance controls. It however is selective in that it decrease the level of mids much more than the bass and treble as Twii stated. It is designed to lower the volume for low volume listening.....I found the C32 loudness far superior which replaced the C32 in my system back in 1979.

I believe it is the only Mac to work like this......Yamaha did something similar which drove me crazy when trying to explain it to customers.

Although I can appreciate the intent of the design, I've never cared for volume-dependent loudness circuits.

TS, you'll probably need to stick with power amplifiers having gain controls when using the C 26.

Update: The C-26 works as it should with the MC250's. It doesn't like the MC-206 six channel amp for some reason. Thanks for checking the schematic cdk.