Yamaha C-70 impressions, questions etc...

Greetings,

Only until few days ago I was not aware how good this vintage yamaha preamp sounds. I wanted capable preamp with top notch phono section, nice tone controls and possibly ballanced inputs/outputs.
My current DiY speakers needed little EQ-boost to compensate for BSC, and I thought that it was a good idea to use tone controls for this instead of fiddling with crossover.
I was wondering how many people are using tone controls on their yamaha pre-s?
I found tone(EQ) controls on yamaha c-70 very capable in terms of adjustments, but unfortunately it seems to me that it takes away plenty of details, decay and overall musicality from records.
However, I must say that sound in direct mode (with EQ off) is really great. I expected much worse result because previously I listened my DAC directly connected through balanced connection into my crown power amplifier.
I took signals from both regular and inverted RCA outputs, and connected it balanced to my power amp. I did not compare with other types of connections because it already sounded great.
Bass also seems to be little louder with preamplifier in line.
Musicality is improved without loosing details.
Phono is also very very good.
I am basically repeating impressions that are many times said before for this preamp, but I just had to chip-in my own opinion

I have one problem with tone controls-right channel sometimes seems to drift away when EQ turned ON, and than return by itself.
Since I mostly listen without EQ turned on it doesnt worry me that much.

Cheers !

Welcome to AK! The #1 complaint on the C70 seems to be relays causing troubles and #2 the RCA jacks being weak. I have one that I also use without the EQ, it sounds very nice. The jury is still out on the phono section- I use outboard phono pre amps for the most part.

Hi and thank you for the welcome.
I donˇt believe that the RCA jacks are problem because channel does not cut out when EQ is off. I also tried switching between mute relay and EQ on/off relay (I think it is RY503) but this would not bring any result.
Someone have idea which relay should I check, or maybe something else?

Of these series of preamps the C-80 and C-85 are the tops. They all have weak RCA terminals so don't use tight fitting interconnects as you will destroy them. The C-70 has monster relays inside that look like total over kill but seem to be troublesome. I don't believe replacements are available? The C-80 and C-85 have traditional relays and even better tone controls than the C-70 (parametric).

Only thing I don't like about these are the RCA terminals and the cases are cheap with lots of plastic.

But they do sound great with very good phono stages.

Wouldn't call them "monster" , but they are prone to failure. The little orange colored relays are about the same size as a TT cartidge.Maybe just a little bigger.

The C-80/85 uses transistor switching --ie. no relays.

avionic said:

Wouldn't call them "monster" , but they are prone to failure. The little orange colored relays are about the same size as a TT cartidge.Maybe just a little bigger.

The C-80/85 uses transistor switching --ie. no relays.

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The C-70 I was in a while back had these big elecro-mechanical relays for source selection? They were huge?

stoutblock said:

The C-70 I was in a while back had these big elecro-mechanical relays for source selection? They were huge?

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Those are not as prone to failure as the little orange cubes.

avionic said:

Those are not as prone to failure as the little orange cubes.

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On the one I had they needed some serious cleaning and cycling of the source button dozens of time until the electrons flowed correctly. That method of switching could not have been cheap?

stoutblock said:

On the one I had they needed some serious cleaning and cycling of the source button dozens of time until the electrons flowed correctly. That method of switching could not have bee cheap?

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I have one of these on my " when I get around to it" shelf.. I know it has at least one of those orange reed relays flaking out in it.

This thread inspired me to put my C70 back in my main rig. I've never been inside of it since I got it from another AKer. Knocking wood, it's working & sounding nice!

I am glad you still like your C-70
Last few days I mostly listen vinyls with "disc direct" on.