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  #1  
Old 09-08-2017, 08:12 PM
Robes Robes is offline
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Thumbs up How to set cartridge loading on Yamaha C-85?

Wow! Last post in 2010?
Hoping to find someone at home here......it's hard to find those in the know on 80's Yamaha Pre amps. I am original owner of a C-85 & M-65 both bought new in 1988. Neither have ever given me a problem-nothing.

NOTE: I have attached specs to my amps

I'm here because I'm upgrading to a VPI Prime turntable and need a cartridge for it. To find a good match it has lead me into the realm of understanding the pre amp I have, the C-85. Through my internet surfing I see that I have indeed bought a good product but, I need to know more about it & I can't find answers to my questions, electronics are not my forte.

I notice that some of the present day "phono stages" (not that I want to get one at this point) available on the market have selectable gain & loading levels, eg. several levels of gain anywhere from 40 - 70+ dB as well as several selections for ohms like 100 - 47K ohms. This is what made me look at what selections I have.

It looks like I have two choices of gain, per the RED BUTTON on the rear Pre amp panel. That being, #1, whatever "normal" dB is on the RED BUTTON and #2, the ("normal" dB) - 10dB, by selecting -10 dB.

My question is, what is the "normal dB"? Knowing the normal dB and - 10dB would then tell me what the value for my 2nd dB level would be. I assume it would be good to know those two dB values when trying to select a good match in cartridge for my system. So, is it correct that I only have 2 choices in dB level on the C-85, and those I don't know?

I also have a problem understanding the line level association. I was told the line level for this unit is 150mV. For example, if a cartridge has a 2.5 mV output voltage you need to multiply it by 60mV to reach line level at 150mV, which then goes to the power amp (M-65). I can understand that. So, if 150mV can be converted to dB is that the value of the "normal" gain on rear panel red button? Then that value - 10dB is the 2nd dB value I could select?

Looking at the front panel Phono switch, I'm only selecting the ohms right? Some carts give recommended ohm loads so that I just pick the closest on that selector right? I also found this: A good rule of thumb (i.e. place to start) is 25 times the coil resistance of the cartridge. That generally winds up somewhere between 100 - 1000 ohms as most moving coils have an internal resistance between 4 and 40 ohms. Then you can vary it up or down 50% (from the 25 times number) until you get the best results.

Bottom line. I've read that the carts with low output voltage eg. 0.25 have to be multiplied far more then higher output voltage carts eg. 2.5 to reach line level value and therefore will then be more of a dirty signal. So are the higher voltage output carts as a rule, the best choice for cleaner signal? Seems more MM carts are higher output over MC carts, but would high MC be best or at least at par with MM of similar output?

So, if I had carts of different output voltages say: .23, .8 & 5.0mV does the pre amp know that voltage and automatically, specifically multiply each to reach/equal the line voltage of the system at 150mV? Because I don't see that I have any control over that aspect.

Well, I'm sure you can see I don't know what I'm talking. Maybe you can suggest something to help me understand some of this so I can buy a good matching cart to optimize my C-85.

Well, lets see if the dead can be resurrected......

Robes
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  #2  
Old 09-08-2017, 08:49 PM
john from seattle john from seattle is online now
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The best way to know is what is considered "normal" for Ohms is 47K, but not all cart follow that so a selection is provided to better match the cart to the phono preamp.

I run my SHURE M97xE at an Ohm other than 47K, I forget what now, I have to open it up and document what I have mine set to, it's the Muffsy PP3, that is heavily based on the Audio Karma CNC design from several years ago.

I found that by running it either at 63 Ohms or 53Ohms gave me a better top end extension, but it is still on the soft side, but that's without inducing too much of an upper mid bump in the process. Capacitance loading will solve that, but I need the pins necessary to swap out the caps to achieve that, but the space for them is provided if you needed them.

Most phono stages that are not adjustable default to 47K in the first place.

I hope this gives you a starting point when it comes to your cart/phono pre combo.
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my system Kenwood KD12-RB turntable, SHURE M97xE cart, Muffsy PP3 phono pre, Receiver: Sherwood RX4030R, TEAC A4300SX R2R, Denon DCM-370 CD changer, Speakers: sansui SP1700 and in testing/restoration phase, Sansui SP-3000, eMachines PC for multimedia use and recently got a Nakamichi BX100 cassette deck
  #3  
Old 09-08-2017, 09:30 PM
Robes Robes is offline
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Hi John, thanks for your input-

In conclusion, from multiple replies on several post on different forums it seems I usually get answers that completely overwhelm me and to which I don't have a clue what they said as well as not answering a specific question of the many I usually ask.

But, what seems to be the final answer is everyone seems to agree my Pre amp will run practically any present day cart I would buy. And, that outside of what manufacturer & audiophiles suggests for loading criteria it really don't matter much, maybe select the MC/MM choices, but in the end switch between all your options till it sounds good.

I still think, it must be possible for someone to look at the Pre and say go with an MM with xmV output and select best sound from your Phone selector and Gain selector, MC go with Highest or lowest mV output and again, select as MM.
I guess I'm left to think just buy something and turn knobs till it sounds best. Yet, if I didn't supply all the specs everyone would say "How can we suggest anything when you don't supply us with the vital specs of your components"
Robes-
  #4  
Old 09-08-2017, 09:55 PM
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GeneL GeneL is online now
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Ok, it's not a Yamaha, but I thought I'd throw up a pic of my 70's Paragon 12A pre....

BTW, I am a Yamaha lover,my favorite right now is my KX-1200U cassette deck.
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My first reel to reel was a Midland 3" rim drive, but I've graduated to a Teac 2340R, Technics RS-1500US, & a Pioneer RT-1050. Oh, and a Yamaha KX-1200U
  #5  
Old 09-09-2017, 08:53 AM
Mark J's Avatar
Mark J Mark J is online now
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Quote:
Originally Posted by Robes View Post
Hi John, thanks for your input-

In conclusion, from multiple replies on several post on different forums it seems I usually get answers that completely overwhelm me and to which I don't have a clue what they said as well as not answering a specific question of the many I usually ask.


Robes-
This is because you are trying to understand the minutia of the issue instead of asking the pertinent question..."I've got tt x with tonearm y (for mechanically matching the cartridge) and a budget of $$$$ and a yamaha c-85 preamp, the only item concerned with electrically 'matching' the cartridge. What cartridge will work well with this combo? I like the sound to be full of ...(describe the sound you like, zingy highs, gut punching lows, sweet midrange or whatever) and I listen to mostly...(describe the music you like). You might mention speakers, too so folks don't get you too crisp with the horn speaker and an AT high frequency peak for example. You will get answers you need to help select a cartridge.


A VPI should have a fine Moving Coil cartridge of low output. Since most of these today have an output of 0.4-0.9mV or 400-900V they will work perfectly with the 100V minimum input for the preamp.

You are trying to learn too much in one step to allow you to select a cartridge.
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10X, 10XD, C300, CD-301, K-12, K-112, K-117, MXD-D3 (x2), MZ-N707, MZ-G750, 7525, RC-9, RS-20, SX-724, TCD-330

Last edited by Mark J; 09-09-2017 at 08:57 AM.
  #6  
Old 09-09-2017, 10:01 AM
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kcbluesman kcbluesman is offline
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Quote:
Originally Posted by Robes View Post
Well, I'm sure you can see I don't know what I'm talking. Maybe you can suggest something to help me understand some of this so I can buy a good matching cart to optimize my C-85.

Well, lets see if the dead can be resurrected......

Robes

The job of the preamp is to optimize the performance of the cartridge, not the other way round.

Optimal performance from a particular cartridge may require a particular impedance or capacitance loading. Your Yamaha preamp has limited choices in this regard - 47K impedance for moving magnet carts, with either 220 or 330 pf of added capacitance, 100 ohm impedance for high-output moving coil carts (using the moving magnet 100 ohm setting), and a choice of 100 or 1000 ohms for low-output moving coil carts.

For optimal performance, you will want to assure that the recommended loadings of the cartridge you choose can be accommodated by the C-85. Most can.

VPI provides recommendations regarding appropriate cartridges for the Prime TT; see here:

http://www.vpiindustries.com/prime

While most recommendations for a table of that caliber will be for moving coil cartridges - the great majority of which the C-85 preamp can accommodate quite nicely - there are certainly some moving magnet carts also capable of doing it justice.

Among them would be the AudioTechnica 150MLX, the Ortofon 2M Black or Bronze and the Nagaoka MP-500. And if your record collection is less than pristine, or your budget is highly restricted, you might consider something with a slightly less-refined stylus...such as the Ortofon 2M Blue or the AT VM540ML.

Finally, don't get overly hung up on cartridge loading or specific voltage gains. If your preamp/phono amp has both MC and MM capabilities, you don't really need to know much more than that as regards gain. Use MM for moving magnet carts and high-output moving coils, and MC for all other moving coils. For impedance loading, close (+/-20%) willl generally be good enough.

If you are the type of person who must have it 100% perfect (vs 99%), you will need to invest in a stand-alone phono amp with a broad array of loading options. Alternatively, if you want to play with impedance loading, you can make up some loading plugs fairly easily....see this link:

http://daveyw.edsstuff.org/vinyl/loading/

Final thought...the 10dB gain button is only there for situations in which the voltage from your cartridge is so high that your volume control becomes overly sensitive (in other words, has only a very small range between very soft and very loud). Dropping the voltage (which is what this button does) would give you back a wider control range. This has very little to do with sound quality, and I would advise that you don't make cartridge output a consideration in your cartridge decision, given that your preamp can accommodate both high and low output carts.

Last edited by kcbluesman; 09-09-2017 at 10:11 PM. Reason: Added info re loading plugs
  #7  
Old 09-09-2017, 10:38 AM
john from seattle john from seattle is online now
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What KCbluesman said,

I did look inside my phono preamp, and I had the gain set to 40dB and the impedance at 47K, or where I had left it with the SHURE M97xE cart, though I think it should be at 53K Ohm to extend the top end a bit and I may need to adjust the capacitance at some point as the SHURE rolls off the top end by attenuating rather sharply at about 8K or so, with increased impedance, the top end extends, but with a risk of a bump in the 5-8K range, but with the right capacitance, I can extend it with a relatively flat response to roughly 15K with a much slower drop off of the top end after that if memory serves.

This is the function of a good phono preamp, to best mate up with the cart, and get the most out of it in general.

So I'm currently running, as an experiment to see if my older Ortofon Super OM-10 is as bright as I seem to recall and thus was tiresome to listen to. Even at 47K, it was not as bad as I remember, and even now with some better speakers with a horn based super tweeter and a horn midrange included with the cone midrange driver for an even more detailed and open top end than my previous speakers.

That all said, I switched the impedance on my preamp to 53K and the cart suddenly went TOO bright, so dropped it back to 47K, but decided to try it at 36K and it attenuated a little the top end, taming it a bit and I'm going to leave it there and see if I like that as the OM series carts tend to extend the top end to about 23K, and in some systems may be too much of a good thing vocally speaking.

I hope this helps you to better understand how this all works and interrelate to each other and the rest of the system.
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my system Kenwood KD12-RB turntable, SHURE M97xE cart, Muffsy PP3 phono pre, Receiver: Sherwood RX4030R, TEAC A4300SX R2R, Denon DCM-370 CD changer, Speakers: sansui SP1700 and in testing/restoration phase, Sansui SP-3000, eMachines PC for multimedia use and recently got a Nakamichi BX100 cassette deck
  #8  
Old 09-09-2017, 11:43 AM
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Mark J Mark J is online now
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From a pioneer SA-8800 owners manual:



Let us know if you have questions about this as that is the starting point for understanding what the changes in capacitance and resistance will do for the MM cartridges. The MC cartridges are a whole nother conversation with the capacitance having little effect and the resistance being a completely different range compared to MM which want in the tens of thousands of ohms. MC usually in the 10-1000 range. HOMC is another discussion, again.

Way too much learning for the simple task of selecting a cartridge.
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10X, 10XD, C300, CD-301, K-12, K-112, K-117, MXD-D3 (x2), MZ-N707, MZ-G750, 7525, RC-9, RS-20, SX-724, TCD-330
  #9  
Old 09-19-2017, 02:44 PM
Robes Robes is offline
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Thanks for the reply kcbluesman-

"Finally, don't get overly hung up on cartridge loading or specific voltage gains. If your preamp/phono amp has both MC and MM capabilities, you don't really need to know much more than that as regards gain. "

So, I'm still finding possible cartridges which I have no way of knowing if I could use them, certainly with the VPI Prime but will they work through my Pre Amp? For example, the Dynavector 17D3 Karat MC states: "will work with any phono pre-amp with at least 60dB of gain". Audio-Technica ART9 MC recommends a gain setting of 56dB. There are others. So I still have no idea what the total gain is of the Yamaha C-85 Preamp. I have searched every available service manual on the Yamaha, owners manuals and forum threads available but have never found a guess or mention of it's gain.

Besides yourself ( in this thread), I also had one of the VPI owners suggest the Ortofon 2M Bronze MM and he was given my Yamaha specs also, yet never made mention of them. I believe that may be the only cart that I could within a reasonable doubt trust to work. I just can't get over how a spec as that is not mentioned anywhere...

I'm inclined to think when I come across carts as the examples I mentioned that I best not consider them. I was considering buying used for some but that could be a big loss for me-
Robes
  #10  
Old 09-19-2017, 06:30 PM
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kcbluesman kcbluesman is offline
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I can't be sure regarding the C85, but I own a C4 that I use in my workshop system and I was told by the tech who rebuilt/restored it for the previous owner that it has 60dB of gain for moving coil and 40dB for moving magnet. He measured outputs using a scope. I would guess that the C85 would be the same.

Think of phono gain as "equal to or greater than"...it's ok if it's higher than the manufacturer's recommended gain. If it's way high, you can use the -10dB gain switch. Too low a gain is more of a problem, as the cart will not perform at its best and you will add noise as you turn up the preamp's volume control to get to the desired listening level.

I really think you will have no problems with most MC carts (and no problems with any MM cart).

Last edited by kcbluesman; 09-19-2017 at 06:48 PM.
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