Need some help sizing an SUT

[jwags81818]

I need more gain out of the phono amp I built and am exploring the SUT route. I have a Dynavector DV20X2H cartridge.
Output 2.8mv
Impedance 150Ω
Recommended load >1000Ω

From the reading I have done and I'll admit I don't have a comfortable amount of understanding but it seems like I would want to increase the output to roughly 5mv to put it on par with most MM carts. What ratio SUT do I want? 1:2?
Then to get my 1000 loading parallel the 47000 with a 5.1k resistor which is divided by 4 the square of my ratio.

These numbers seem a bit extreme. Is the output of my cart too high to use a SUT?
I also posted about raising the gain of my amp. Maybe if thats possible would be a better solution?

 

[analog_sa]

This cart is a poor candidate for a SUT. Raising the phono stage gain is not always a great option, really depends on topology. Don't you have a line stage?

 

[6L6]

Being the “H” model, your cartridge is intended to be used straight into the MM input of your phonostage.



You mention something about raising gain, what phonostage are you using?

 

[jwags81818]

I an running a 300B SET amp with autoformer volume controls. No linestage. Phono amp is the ANK L3 phono kit, I don't need a ton of gain. Say 1/4 of my volume knob would get me back where I want to be. I know this cart is suppose to work with a MM input but then again they made the output 1/2 the level of most MM carts.

 

[jwags81818]

This is my phono stage..

 

[6L6]

Say 1/4 of my volume knob would get me back where I want to be.

So you have enough system gain, but only if you turn the knob “further” than you’d desire?

 

[jwags81818]

Correct sir... that is it exactly.

 

[jackinnj]

You're throwing away the gain of the first stage using a passive RIAA compensation network AND as the tube ages, r(A) changes so the compliance to the RIAA curve will change from optimal.

 

[jwags81818]

Well this is what I have. Any way to increase the gain a little? Raise the voltage? Change a resistor value?

 

[6L6]

In all seriousness…

Turn up the knob.

Problem solved.



You already have the gain, you just need to adjust the knob so you throw away less of it. (Because that’s how volume controls work…)

 

[jwags81818]

even on full I don't think it will get as loud as my other sources

 

[6L6]

Ok, that is useful information.

So… turn it all the way up and determine if it can get loud enough.

Report back.

 

[jwags81818]

even if it can I would rather keep all my sources more closely matched level wise.. Looking at the schematic I posted is there anything simple I can do to increase gain? What about rolling in a 6N2P for the 6922?

 

[6L6]

Eh. In that circuit things would get pretty messed up. Go back to the SUT idea.

Rothwell makes one specifically for HOMC -


http://www.rothwellaudioproducts.co.uk/html/sut_for_homc.html

 

[jwags81818]

THANK YOU...
That is the ticket right there.. I love my cartridge since I had a boron cantilever and a new diamond put on it. That is the ticket for sure....

 

[6L6]

Boron is awesome. Who did the work?

 

[analog_sa]

as the tube ages, r(A) changes so the compliance to the RIAA curve will change from optimal.

Seriously? With a 270k resistor?

 

[jwags81818]

VAS in NJ did it. I moved to PA from Oregon and my stylus didn't make the trip. When it arrived it was missing. The cantilever broke due to the extreme cold weather and riding in a truck. He did it fast for like $400 if I recall correctly. I couldn't believe the improvement the boron made. It was a major upgrade in the sound. He did it fast too. His shop was packed FULL of gear to die for. I didn't want to leave..

 

[russc]

Pad your other sources down to the same level so you have volume on 7/8 for all sources.
But then, my budget doesn't stretch to MC carts & SUTs.

 

[jackinnj]

You can change the values of R9 and R5