Let's discuss the different head amps folks are using...or SUTs

Blue Shadow

Waiting for Vintage Gear from this century
I started this thread to get info on the SOTA head amps that 4-2-7 has decided to collect as they work well in his system. He complied and supplied what appears to be all the info he has on them.

To make this thread a bit broader, let's open it up to a discussion of the moving coil phono preamplifier or head amp, a device that amplifies an LOMC about 20-30dB to allow it to go into a standard MM phono input. Another device that does the same thing but is passive is the step up transformer. We'll put that in the discussion, too.

Since this is a discussion of a NON-equalized 20-30 db gain amp/transformer, it does not include all those generally newer phono preamps that have line level outputs. Looking to discuss the LOMC into MM phono amplification options at this point.

I'll ask Billfort to change the title to reflect this broadened topic.
 
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SOTA started earlier than that in Oakland CA, I also have three different types of the amp and the manuals. I'll weigh in after work
 
I had bought a NOS in a seald box and here is the paper work..

img008_zps7whjaqkw.jpg~original



img009_zpspdbyvhks.jpg~original
 
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How does using a step up transformer like this (That is what this is right?) through a regular phono stage compare with just sending the signal to an MC stage... Is there some sort of inherent advantage to this?
 
Alright I have 4 of these things and they sound great so that's why I have 4.

Here is a rechargable unit and is the last one I bought, sold as parts only. No charger and the batteries are original and the contacts were broken when I got it.

IMG_2535_zps92smcdhg.jpg



IMG_2538_zpslxrvvtqd.jpg



IMG_2532_zpsqq0oxsgu.jpg



IMG_2533_zpsrr5vbdzf.jpg
 
How does using a step up transformer like this (That is what this is right?) through a regular phono stage compare with just sending the signal to an MC stage... Is there some sort of inherent advantage to this?

Lets see:scratch2:

It's a head amp not a step up transformer (SUT) Blueshadow can discribe the difference better i'm sure. It has to do with the SUT is not powered and the Head Amp is.

If you have a HOMC and use it in a MM input while it works, your overall systems volume level when playing records will be quite low.

The same HOMC played though a MC input while it works very good, will have higher gain and your overall system volume will increace.

Enter the head amp and truthfuly was designed at a time when built in MC inputs were not as common and the LOMC was getting popular. So something needed to be done and a head amp was one of the ways to boost the signal of the LOMC cartridge to play in the MM input. Other wise unlike the HOMC above you would not really hear anything and in fact thats why they started to make HOMC so that they will play without any further boost.

Now as above you can play a HOMC in the MM & MC Stage of your preamp/reciever that has RIAA EQ. The MC input adds gain to boost the signal higher than you would get playing it though the MM input. I can add the head amp between the cartridge and eather of thes inputs and add even more gain not to mention it has adjustable impedance settings. What I get from doing it is a vinyl playback front end that blows away any of my other sources and is equal in total output of say a CDP. I also get an awesome soundstage that really raises the celling and makes my smallish room sound like a concert hall.
 
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BTW this is now the most info and photos you will find anywhere on the internet about the SOTA Phono Head Amp.
 
BTW this is now the most info and photos you will find anywhere on the internet about the SOTA Phono Head Amp.

The reason I asked. And I did wait until you said you have bought all the ones you need.

I like the box..."Batteries not included."

With these units showing up occasionally it is nice to see the specs, gain and impedance info are most helpful.

I have a Musical Fidelity AC-1, had two but sold one and Tom Clone bought a third one but no one has any of the paperwork for it. Since I bought mine with a consignment TT back in 86, it is from the same era at the SOTA. The AC-1 is also fully shielded, but has set gain and internally fully adjustable cartridge loading (by installing resistors). I've added a nude of the AC-1.
AC-189.jpg

On another board, I asked about this unit and got one response with as much info as the poster had available: “From my 1982 Audio Annual Equipment Guide: Dual Mono Design for Moving Coil Cartridge. Adjustable Input Impedance. THD .03%. IHM IM Distortion .03%. Input Capacitance 250pf. Does not invert phase. Max Output 2 Volts. It sold for $550.”

This unit runs on a ±voltage wall wart that is hard-wired but also has an AC line cord so it isn't really a ww, just a wart. The AC cord is 24" long or so and the low voltage wire is quite long.

Let's get this discussion back to the SOTA for the Q & A after our presenter 4-2-7 opens the floor for questions. If that doesn't happen maybe we change the title of the thread and talk about MC head amps also known as pre-preamps. Thanks for the info on this unit.
 
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The reason I asked. And I did wait until you said you have bought all the ones you need.

I like the box..."Batteries not included."

With these units showing up occasionally it is nice to see the specs, gain and impedance info are most helpful.

I have a Musical Fidelity AC-1, had two but sold one and Tom Clone bought a third one but no one has any of the paperwork for it. Since I bought mine with a consignment TT back in 86, it is from the same era at the SOTA. The AC-1 is also fully shielded, but has set gain and internally fully adjustable cartridge loading (by installing resistors).

On another board, I asked about this unit and got one response with as much info as the poster had available: “From my 1982 Audio Annual Equipment Guide: Dual Mono Design for Moving Coil Cartridge. Adjustable Input Impedance. THD .03%. IHM IM Distortion .03%. Input Capacitance 250pf. Does not invert phase. Max Output 2 Volts. It sold for $550.”

This unit runs on a ±voltage wall wart that is hard-wired but also has an AC line cord so it isn't really a ww, just a wart. The AC cord is 24" long or so and the low voltage wire is quite long.

Let's get this discussion back to the SOTA for the Q & A after our presenter 4-2-7 opens the floor for questions. If that doesn't happen maybe we change the title of the thread and talk about MC head amps also known as pre-preamps. Thanks for the info on this unit.

I don't really know anything technaly about this kind of stuff I just plug things in to see if they work....:D

Truthfully It had a SOTA name on it at the auction site and I had to have one. The end result was it works good within my system. I have had other stand alone stages and nothing sounded as good. The Coph Nia was close but good luck finding one of those, I had #8 & #9 and sold 8 and still have 9 it was a Michael Fremer test unit.

It's your thread and nobody uses head amp and I don't know why. But if one is into vinyl, MC carts and wants great SQ they need to start looking at these "Head Amps"
 
Back in the day the head amp was the way to go for the most part. Many companies had these available. Some had transformers for SUT, even Pioneer for their receivers. But the active amplifier was considered the better unit, generally. Today there is a strong movement to the SUT and some wouldn't even consider another amplifier in the chain unless it went from MC to line level.

I'll watch this thread and see what might make it more popular instead up us talking to each other.
 
Back in the day the head amp was the way to go for the most part. Many companies had these available. Some had transformers for SUT, even Pioneer for their receivers. But the active amplifier was considered the better unit, generally. Today there is a strong movement to the SUT and some wouldn't even consider another amplifier in the chain unless it went from MC to line level.

I'll watch this thread and see what might make it more popular instead up us talking to each other.

I did find this quite interesting


img014_zpsrsinlflc.jpg
 
I have always been in the SUT camp but find this discussion interesting and informative.

Thank you for the wealth of information. [emoji106]
 
D'oh.....Guess I should post what I listen to.

My favorite SUT is the Quicksilver Audio followed by the Denon AU-320 and the Ortofon STM-72.

Also have a PS Audio Head Amp.
 
are you using a vlomc cartridge with the stm-72? Here is a pic of that unit:

Ortofon.jpg



that unit has lots of gain, having been designed to go with Ortofon's MC20 with a 0.07mV output. The more expensive MCA-76 was the head amp for that cartridge and its gain is spec'ed at 34.5dB, much higher than the typical 20dB or so.

Here is the MCA-76:
MCA_76.jpg
 
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Back to Blue Shadows unit, I found it to be very quiet with wonderful attack and decay with a Ortofon MC20. This was into a Acurus RL11 line stage.
Regards,
Jim
 
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