FOUND: SUT, Moving Coil Step up Transformer.

[classicallover]

Price Range: Negotiable. SNA, HIFI Shark rates.

Item Condition: Good.

I want to compare my MC phono stage with a SUT plus MM phono stage.

I am looking to buy a step up transformer ideally based on the  Lundahl transformer but will also consider CineMag, Altec Lansing, Hashimoto HM-7 depending on condition, price and performance.

 

The required ratio: 1:10 to 1:20. Ideally closer to 1:20.

Current cartridge is a Hana ML with an output level of 0.4mV/1kHz, impedance of 7Ohms/1kHz and suggested load impedance >100Ohms.

 

Brands/models that I'm thinking (not exclusive): Bob's Devices SK-20, Ortfon Verto, K&K Audio, Auditorium 23, Hashimoto HM-7, Cinemag 1251, Rothwell MCL.

Edited yesterday at 11:02 AM by classicallover

[andyr]

Have you thought of using an active 'head amp' ... instead of a SUT?

 

The advantage of a head amp is that gain can be altered without affecting the optimum cart loading - whereas a SUT imposes a loading which depends on the SUT's coil ratio.  For instance (with the standard MM phono stage loading of 47k):

• a 1:10 SUT delivers a maximum of 470 ohms (this can be lowered)
• a 1:15 SUT delivers a maximum of 209 ohms
• a 1:20 SUT delivers a maximum of 118 ohms.

(The equation is: resulting cart load is:  47000 / (squ of the coil ratio).)

 

For a 0.4mV Hana ML and a standard 40dB (100x) gain MM phono stage ... I would suggest the best gain is ~15x.  This is because the standard 100x MM gain is designed to deliver 500mV output with a 5mV MM cart.  15x 0.4mV ... is 6mV - whereas:

• 10x delivers only 4mV and
• 20x delivers 8mV - which I suggest is a bit too high for a 'standard-gain' MM phono stage.  (Note: some MM phono stages have <40dB gain; some even have more.)

And the Hana coil impedance of 7 ohms, I suggest, will have an optimum loading of between 70 (10x) and 700 (100x) ohms.  With my 'Paris' head amp ... you can try any res value between these.  

 

[classicallover]

2 hours ago, andyr said:

Have you thought of using an active 'head amp' ... instead of a SUT?

 

The advantage of a head amp is that gain can be altered without affecting the optimum cart loading - whereas a SUT imposes a loading which depends on the SUT's coil ratio.  For instance (with the standard MM phono stage loading of 47k):

• a 1:10 SUT delivers a maximum of 470 ohms (this can be lowered)
• a 1:15 SUT delivers a maximum of 209 ohms
• a 1:20 SUT delivers a maximum of 118 ohms.

(The equation is: resulting cart load is:  47000 / (squ of the coil ratio).)

 

For a 0.4mV Hana ML and a standard 40dB (100x) gain MM phono stage ... I would suggest the best gain is ~15x.  This is because the standard 100x MM gain is designed to deliver 500mV output with a 5mV MM cart.  15x 0.4mV ... is 6mV - whereas:

• 10x delivers only 4mV and
• 20x delivers 8mV - which I suggest is a bit too high for a 'standard-gain' MM phono stage.  (Note: some MM phono stages have <40dB gain; some even have more.)

And the Hana coil impedance of 7 ohms, I suggest, will have an optimum loading of between 70 (10x) and 700 (100x) ohms.  With my 'Paris' head amp ... you can try any res value between these.  

 

Hi Andy,

 

Thanks for your input and suggestion. I am trying to stick to a SUT due to the lossless nature of the passive transformer. It is my opinion that with an active headamp, by  amplifying the voltage is impossible not to alter the audio signal and thus the music will not sound as clean.

[andyr]

12 hours ago, classicallover said:

Thanks for your input and suggestion. I am trying to stick to a SUT due to the lossless nature of the passive transformer. It is my opinion that with an active headamp, by amplifying the voltage is impossible not to alter the audio signal and thus the music will not sound as clean.

 

Aah, that's a shame, c.  

 

My own view is that you in fact get a cleaner signal from a head amp than a SUT.    (It's just a different religious view to that which you have.)

 

Edited April 29 by andyr