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Yamaha C-80 puts out anemic signal??

Z

zangsax

New Member
Hi. I need help. I bought a Yamaha C-80 preamp on E-bay ( yeah I know) and I have to turn it all the way up to get a reasonable level, If I put a Carver C-1 on the same system I get tons of level and drive my carver TFM-15 power amp to mars (not that it sounds good that way) even when the Carver is not cracked much at all. Is something really wrong here? I do plan to get a much more powerful amp when I can afford it but it seems that the carver should? least get loud the way it does with another preamp. My Dynaudio contour 1.8 MKII are even driven with a no big deal sony receiver of 80 WPC. If this is normal for a high end Yamaha preamp? Will going to 350wpc from 120wpc solve this? The C-80 sounds beautiful. But can't drive my amp and I'm not a very loud music guy at all.
Ist preamp from ebay DOA , 2nd this one ,3rd Carver C-1 and I don't like the way it sounds. I think I,m learning something here but I can't afford it. Thanks for any help. I'm a professional jazz musician this is imp. to me.
 
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My C-80 has plenty of output.

What is the source?

As you may or may not have noticed, the C-80 has a dual concentric volume and loudness control. The outer ring is a variable loudness control and the inner knob is the actual volume. Have you experimented with various positions of both controls?

Either adjustment can/will affect the overall volume.
 
My pre has a -20dB level switch for high-gain amps, you might look for a similar setting on yours... I can't imagine you've got that much of an impedance mismatch, but what are the rated impedances of the pre and power amps?
 
Have you tried both the normal out and the inverted out?
How about using different inputs - Aux, Tape 1, Tape 2, DAD, Tuner ?
Check the inputs with the headphone output?
Don't leave headphones plugged into the preamp, it mutes the output.
Try the rec out if the amp has level controls and set them way low. Or feed the Yamaha tape output temporarily through the Carver, this will also check to see if the problem is before or after the volume control. Watch out for that concentric loudness - it is great once you get used to it.
You did get the manual, right? Find it on the Yamaha website.
Let us know, we also want it to work for you.
 
There is no attenuator switch per se on the C-80, only a phono gain pushbutton on the back panel.

The output impedance of the C-80 is like 47 ohms so it should be able to drive darn near anything.
 
whoaru99 said:
There is no attenuator switch per se on the C-80, only a phono gain pushbutton on the back panel.

The output impedance of the C-80 is like 47 ohms so it should be able to drive darn near anything.
Click to expand...

I kinda figured that but had to ask. Is the C-80 cap-coupled output? If so might be something to check...
 
Thanks for your input_heres the deal

I have tried both outputs, reg and inverted. I have tried all inputs including phono set at high gain. This all yields the same result-sounds great no dynamic room The phones out yields the equivilent of speaker level into the phones. I think you should have to take them off all the way up. Again I'm a classical and jazz guy with some 60's-80's jazz funk so I'm not trying to shake anything. When I tried the C-80 record out and slowly turn the channels up on the power amp I get what I expected from the preamp outs i.e. it's a little hotter than carver pre outs but in the same ball park. Way hotter than the C-80's own pre outs. I can certainly make it louder with the loudness control but i like the way it sounds when loudness is off because these speakers are great, the room is pretty good, and I listen to well recorded material since I've spent plenty of time in recording studios myself. I notice the loudness control is not radially synced with the volume control but I think that's just mechanical and I can fix that right now with a screwdriver.. Thanks for continued brainstorming It's fully appreciated. Zangsax (John Z)
 
First; here is a link to the manual :) http://www2.yamaha.co.jp/manual/pdf/av/english/SepA/C-80.pdf

Now the second thing; Yamaha is different regarding Loudness than others, they cut where others boost. So to turn off the loudness you have to turn the knub all the way to the right! As a jazz man you will like the way Yamaha is doing it, read about it in the manual.

It seems you have allready checked the mute button, but do it again (after adjusting the loudness).

If non of this works it seems the Volume pot is dirty and has to be cleaned/changed, but before doing this thy to massage it by turning it up and down a lot of times. It is a normal malfunktion on old Yamaha pre's, so don't wory too much as loong as you get a good signal out of the rec out. The phones out is also controlled by the Volume pot, so therfore the problem will be the same as main out.

You may try to force a conecktion in the Volume pot by lifting a bit on the knob while turning, but be carefull doing this and only for diagnose sake.


Hey Autobot... no looking over the sholder!! :)
 
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Thanks Autobot! This forum is a great resource

After using too many graphic EQ's in my life, I assumed the loudness control boosted highs and lows as opposed to dumping mids as it does. They of course are synced as they should be and I have proven for 756,452 2nd time the adage " If you assume you make an ---------------" My DOA was a C70
will I like it better if I am able to fix it (in your opinion). Thanks again, Zangsax
 
zangsax said:
After using too many graphic EQ's in my life, I assumed the loudness control boosted highs and lows as opposed to dumping mids as it does. They of course are synced as they should be and I have proven for 756,452 2nd time the adage " If you assume you make an ---------------" My DOA was a C70
will I like it better if I am able to fix it (in your opinion). Thanks again, Zangsax
Click to expand...

:scratch2: Now thats a tough call since I have not auditioned the C-80 and it is the top flight unit to the the C-60 which I got one of those for for my nephew feeding a M-50 and is does sound great really great. :thmbsp:

So without me actually comparing the C-80 to the C-70 I really cant say.

That question would be better answered by someone with more experience
The-Real-Mandak
image.php


Heck even I have a question.. for him...
Is the C-70 the only unit that had the Varigain Volume control?
When the rest all have the 4-Ganged?
 
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I believe the theory is that you turn the loudness control "flat" by turning it fully clockwise/right. Then, you set your maximum desired volume with the volume knob.

Then, from that point forward, you control the volume with the loudness control so that the loudness curve is theoretically applied correctly throughout your selected range of volume.
 
zangsax said:
My DOA was a C70 will I like it better if I am able to fix it (in your opinion). Thanks again, Zangsax
Click to expand...

If you use a tt I have no dought you will like the C-80 better, if has a newer phono design than the C-70. The C-80 phono design was spoken highly about back in the days and in general I think the C-80 has a small advantige with stuff like ZDR to the C-70, but we are talking small stuff here.

Autobot: yes I think the C-70 is the only one with the varigain volumecontrol, but I don't really think this a an advantage - depending on how it works.
 
ryuuoh said:
The C-50 uses the varigain circuit. You can dl the brochure I scanned in the yamaha manuals linky.
http://www.audiokarma.org/forums/showthread.php?t=154865&highlight=yamaha+database

The file is c-x0_m-x0_t-x0-b.pdf
Covers the c-50-70, m50-70.
Click to expand...

I am such a geek I downloaded that brochure then had it professionally printed and bound. (looks great BTW)
and read it cover to cover the C-50 uses the 4 ganged volume.
As where the C-70 uses the Varigain.
Which actually works at the line level much like an amplifier with level controls does.
here is the C-70 volume pot it is not as long as the C-50 pot
C-70VOL.jpg

now the C-50
FridayJune1920093.jpg
 

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A little funny; first they say how fantastic this new volume control is, then they say that the 4-gang volume of the C-50 takes care of the conventional problems. Hmm...

The varigain way of doing things also persent a problem, any amp has a sweet spot where it creats a minimum of distortion. So for optimal sound it's all about getting as close to this a possible, if you take a look at some of the Yamaha pro amp manuals you will find a curve showing the distortion at different levels. The same is going on in a pre amp and low levels of sound signal is not easy to deal with, just think of the phono stage. So not just good things in the varigain volume, Yamaha also left the design with bough the C-2x and C-80.

Not saying the varigain is bad, just that it presents new problems.
 
I just purchased one of these. If there's a volume problem the first 2 things I would look at are Audio Muting and the Variable Loudness Control.
 
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