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Yamaha C-70 Phono Preamp Question

B

back2audio

New Member
Hello all-

Been enjoying my C-70 for years. Lately I’ve been further modifying the analogue output stages on some of my older CD players with Vishay film resistors in place of the OE carbon crap.

Got me thinking- has anyone replaced the resistors with higher tolerance metal film types in the MC and or MM section? I did all the electrolytics with Nichicon and the Muse variants in the phono signal path some time ago.

My C-70 aside, has anyone heard any appreciable difference upgrading type and tolerance of resistors in their pre amp phono circuitry? This of course, is asked with the caveat of modifying “Mid-Fi” to higher end equipment to start with.


Cheers-
 

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I have seen quite a few threads where people replace resistors. I’m not sure if the title of your post will attract those people.

Rob
 
Thanks much Rob. I can’t edit the title now.

Didn’t find anything on the resistor topic searching specifically for C-70 so started a new thread.
 
I haven't specifically worked on this preamp but am aware of its great reputation for SQ. In general terms though, the effect or change in sound (if the effect is audible at all) with metal film has been the same regardless -at least from my experience. For me, the change when going from carbon film (and carbon composition probably moreso) to metal film is towards a cooler, more modern/ detailed sound. One thing you can do is ask yourself what do you like about the sound of the C-70? What, if anything, don't you like about it or wish sounded different with regards to lows, mids, highs / emphasis or under-emphasis, etc? I've heard it's quite a good preamp to begin with already and probably sounds pretty "balanced"?

Looking at it this way can sometimes help inform component choices to achieve an end desired result if you notice a particular discrepancy somewhere. If it sounded pretty "balanced" for starters, I am not sure if I would do more than recap, because changing out all the resistors may alter the sound signature. Then again, even though it may sound just fine/ balanced before, you may think it sounds even better with new caps and resistors. It's possible that as good as it was before, it will turn out sounding better afterwards. Sometimes you can reach a point of diminishing returns where it may even sound worse as well if you change too much (depending). My experience is that it usually doesn't end up worse afterwards as long as materials going in are of higher-quality than oem or have different/better electrical properties and characteristics compared to originals.

For sure, the UES caps you used are some of my favorites and always sound better compared to what was in there before in all cases that I've heard at least. This, despite the fact that even something that sounded "good" all-around before always sounded "better" all-around with them afterwards. This is when they (Muse BP) were compared to both the old caps that came out as well as the best (new) general-purpose types with the best specs I could find.
 
Thanks for the input.

Soundstage and clarity is what I’m looking to improve. Even if barely audible it’s still a fun exercise to do the board level work and rewarding to complete.

Agree, tighter specs, improved caps- all should point towards improving performance. I’ve not been disappointed on any CD player yet, nor was I with an NAD pre amp phono section I did the same to a while back.

I did a few searches on the C-70 and never saw a resistor specific thread. I’ll keep digging.

Appreciate it!
 
Just keep in mind. Some of those resistors may be fusible. <---- Do not deviate resistance or wattage. Flame-proof coating is a must. Fire hazard.
 
avionic said:
Pretty damn good sounding crap. Your C-70 would benefit more with a SW503 upgrade and a new set of HB2E-DC24V relays.

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The SW503 was my first modification.

I’m not familiar with the relays- thanks for the mention.

I say crap as things below Vishay metal film in the signal path to me are less than desired
 

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