Phono Amp Spec’s

@viridian Thank you again for your reply.  Believe me, it is very much appreciated!

I understand that the KAB is suggesting the optimal gain for my cartridge is from 43 to 53dB.

However, as @tablejockey had correctly posted above... the Benz website says my cartridge is ideally suited for tube phono amps that have 50-60dB of gain.

I have used my cartridge with phono amps that had 40dB, 52-54dB and 60 - 62dB.  I have found that "in my system" the cartridge really comes alive and is full bodied with at least 60dB of gain and it works beautifully with my current 62dB all tubed phono amp.

Based on these experiences, I was hoping 64dB would be close enough and still work well, but obviously I am concerned about the overload margins with this new phono amp.

I was really hoping to avoid the use of step up transformers, because oftentimes you may have to deal with hum - due to placement, etc.

I do have an extremely nice vintage Hirata Tango step up transformer that offers 1:6.6 ratio.  There are times when I get no hum and then other times when I do... it can be frustrating at times.... but when there is no hum - it's simply stunning!

Anyhow, I'm at a point in my life, with all of my health issues, etc I don't want anymore stress.  So, I guess that is why I'm trying to avoid using my SUT if at all possible.

Best wishes,

Don

"I do have an extremely nice vintage Hirata Tango step up transformer that offers 1:6.6 ratio.  There are times when I get no hum and then other times when I do... it can be frustrating at times.... but when there is no hum - it’s simply stunning!"

That means the sound of your MM Phono is stunning. That is why I use a SUT, to keep using my beloved McIntosh tube preamp mx110z's MM Phono EQ.

You simply MUST find a hum free location for the SUT, put it inside an isolation box  ,,,,, different length or type of cables ..... Don’t walk away from ’stunning’.

Your cartridge's impedance is 38 ohms, they say it should see around a 400 ohm load (that fits the formula 38 x 10 = 380 ohms).

That cartridge: you might need a unit that provides separate control of gain and impedance. My Fidelity Research FRT-4 SUT (gain and impedance are a 'resultant' relationship) to 'get' 470 ohm load, it would be x factor of 10.55 which may be too much signal.

..........................

@elliottbnewcombjr 

Hello and thank you for your message!

When you say an isolation box.... what materials should it made of?  

Is this something that I would build, or is this something that you purchase?

I do love the Hirata Tango transformer... when it doesn't cause any hum, that is.

Best wishes,

Don

2db's over the stated "optimal" range is likely negligible.

You'll maybe experience a click or two more sensitivity on the volume knob?  

I wouldn't stress over it. 

With that spec showing overload occurs at 5.7mV output from the cartridge when the phono is set for 64db gain, and given that the cartridge has a nominal output of 1mV, then for a hypothetical 20db of overhead margin, you would like to see at least 10mV before overload.  5.7mV is about 15db of margin above the nominal 1mV of output. "db" are in log scale so half the voltage is not half the db.  As others have mentioned, 64db is probably more gain than you need, but the next lower gain you can select, if it is 40db, is too little gain. You are better off with 64db, IMO.  As for the rest of it, just listen. If you hear distortion on loud passages, maybe the cause is phono overload but maybe not, as distortion on loud passages can have many other causes as well.

In general, the overload margin of a phono stage is inversely proportional to its gain; the higher the gain, the lower the overload margin, but since you use high gain with cartridges that have a very low output to begin with, overload is less likely to be an issue. Also, in general, tube phono stages tend to have a higher overload tolerance than SS ones.