C-85 preamp?

valicious

AK Member
Is it any good? There's one on the bay I've been watching. I'm looking to replace my Denon receiver that's being used as a pre right now.
Which is generally better, the CX- or the C- line? I'll be playing FLAC files from my computer. I do need multiple inputs though.
How much is a good deal on a C-85?
 
Control amp

What do you mean "control" amplifier?

I'll take a stab at in and Avionic or others can correct me or chime in. The 'power' amp like a Yamaha M-85 amplifies the sound (really the relatively low frequency electronic signals that a speaker converts into pressure waves - say 20 Hertz to 20 kHz) and the 'control' amp controls the volume, "shapes" the sound, determines which source goes to the power amp or tape deck, etc.
 
The C-85 is a great sounding little pre-amp with a fine phono stage. It has great parametric tone controls if you are into that sort of thing. The adjustable loudness is a little funky but works. The switches seem a little cheap but I find them more reliable than some of the older (cooler) Yamaha mechanical switches.

The bad, the case is a little cheap with some poor use of plastic in some critical areas. The RCA terminals are typical for the era but can come loose from the PCB causing problems.

I sold one with upgraded RCA terminals for around $200 he on BT a few months back.
 
Is it any good? There's one on the bay I've been watching. I'm looking to replace my Denon receiver that's being used as a pre right now.
Which is generally better, the CX- or the C- line? I'll be playing FLAC files from my computer. I do need multiple inputs though.
How much is a good deal on a C-85?

I have a C-80 which is identical to the C-85. I bought mine on eBay for $200 in great working condition. A few months into owning it I had one of the pre-amp output jacks fail. I took it in and had that repaired for about $75. More recently, after owning it for a bit over a year, it developed a new problem where after being on for about 5 minutes, all I would get is a hum. It's back at my tech right now having that issue fixed, to which he told me it would cost ~$135.

Both of the issues that I had are relatively common with these units from what I understand. One thing is that these units run pretty hot, which might be at least part of the problem.

I really love my C-80. The main reason I got it was so that I could use it's inverted pre-outs to bridge some of my amps. I wasn't expecting to be blown away by just how good it sounded, and how much better it was than what I was using as a preamp before. Even when I use it to drive my Beyerdynamic DT990-Pro headphones it sounds amazing. My poor C-80 was being used almost all day long some days.

I hope my tech does a solid job because I'm counting the days until I get my preamp back. It left a big void in my system that would be difficult to fill otherwise. I never once regret purchasing the C-80 despite the additional repair costs.
 
I have a C-65 which I really like. It has a great phono stage with a lot of adjustmenets. It is like the C-85 but has simplified tone controls. Otherwise the same problems that afflict the C-85 can also afflict the C-65, though the series is definitely a worthwhile investment.

Mine had bad main power supply caps when I bought it, which I changed out with quality replacements. It has worked perfectly ever since. there are a lot of electronics in these and no ventilation in the case, which is why they tend to get so warm inside. I've considered adding ventilation to my case, but haven't done it.

Definitely DO read the operation manual if you get one - as has been mentioned the loudness control is a bit funky, but once I understood how it was supposed to work I've grown to love it.
 
Last edited:
I truly love my C-85.
Mine does not run particularly warm but has recently developed a bad RCA out. Damn.
 
The bad, the case is a little cheap with some poor use of plastic in some critical areas. The RCA terminals are typical for the era but can come loose from the PCB causing problems.

Stoutblock,
Interesting what you say about the RCA terminals. I have a C-60 that over the last serveral months has been acting flaky with the Phono 1 now also Phono 2 inputs. The right channel would drop out. If pulled out TT phono plugs then reseated it would be OK for awhile then drop out again. I suspect this is a RCA/PCB cold-solder joint problem. Just procrastinating putting the pre-amp on the bench and opening up to investigate further. So, is this a common problem with this series/vintage Yamaha pre's and once opened is this something pretty easy to trace and resolder?

Bill C.
 
This is a common problem with many brands of equipment from the 80s. These stamped RCA terminals that are soldered directly to the PCB will have problems. I have upgraded a lot of equipment through the years to modern RCA terminals and have never been sorry. I you used modern (tight fitting) interconnect, it will damage these old terminals quickly.

Stoutblock,
Interesting what you say about the RCA terminals. I have a C-60 that over the last serveral months has been acting flaky with the Phono 1 now also Phono 2 inputs. The right channel would drop out. If pulled out TT phono plugs then reseated it would be OK for awhile then drop out again. I suspect this is a RCA/PCB cold-solder joint problem. Just procrastinating putting the pre-amp on the bench and opening up to investigate further. So, is this a common problem with this series/vintage Yamaha pre's and once opened is this something pretty easy to trace and resolder?

Bill C.
 
I found a CX-1000 in super mint condition, so I ended up snagging that instead.

:thmbsp:

Not everyone uses the optical inputs nor needs the second set of outputs to run a second amp, but it's nice to have those options in the CX-1000 (and the remote!).
 
The CX1000 didn't have the remote, so I'll have to buy that separately.
Anyone know a good place?

I love having the luxury of using the remote on my CX-1000.
I found my CX-1000 at the local thrift for 7 bucks but sans remote.
By chance I found that the remote from the RX-900 thru 1100u receivers from the same year(s) remotes worked.
Keep an eye on Ebay.
 
I love having the luxury of using the remote on my CX-1000.
I found my CX-1000 at the local thrift for 7 bucks but sans remote.
By chance I found that the remote from the RX-900 thru 1100u receivers from the same year(s) remotes worked.
Keep an eye on Ebay.

0.o
*drools*
 
All of the suppliers I've used for original Yamaha remotes show the remote for the CX-1000 or any of the compatible ones I'm aware of as "no longer available". So it looks like eBay might be your only bet for full-function (or nearly so, with compatible, as for CX-600, 800 or those mentioned by tubed above) remote.

The remotes for CX-600 & 800 are identical with the exception that they have fewer direct input selection buttons, i.e., only one DAT, and only one VCR, etc., since those units have fewer inputs compared to the CX-1000.

Otherwise, they'd let you, power on, select *most* of your inputs, play/cut phono, operate the tuner, operate a tapedeck, operate the CD, and control volume--so there'd be most of the utility in a romte for a 600 or an 800, if you could find one on eBay.
 
Search eBay with number 121016017678. This brings up a non-original replacement purporting to work with the CX-1000 "out of the box". It *does* appear to have the majority of the functions, just organized a bit differently from the original.
 
yamaha c 70 distortion

Hello everybody. I have a c 70 with loud distortion on one channel. Channel 2 works fine. Problem is on all inputs with tone disabled or enabled. As soon as balance control is moved off hard right, problem occurs. Measured resistance on balance control (both sides) and it is in spec.

I checked all the usual suspects ( de oxit all interconnect cables, & balance contol)re flowed solder joints on balance and volume, etc.
Replaced op amp bypass caps ( 0.1 UF0 to no avail.

Power supply caps show 600 mv ripple.

Any Ideas?
Thanks in advance for any advice.

Best regards
thaedra
 
There is are 5 little orange reed relays that are notorious for going intermittent in that C-70. Tap on them one at a time and see if your distortion clears up intermittently.
 
Back
Top Bottom