SUT or SS LOMC preamp

Re: SUT or SS LOMC preamp

Postby edw » Sat Mar 03, 2018 9:53 pm

audiom3 wrote:I'm curious if you guys have compared a SUT to running your MC cartridge directly into your phono preamp 'wide open' (@47k) assuming you had ample gain available. And if you did and you still prefer the SUT, what exactly were the benefits/improvements over just the phono stage? Thank you.


I do prefer the SUT over just a phono stage (Lehmann Audio Black Cube SEII and Decade). t's a bit hard to describe but, with the SUT inline, there was improvement in air around voices and instruments, dynamics, and low level detail and decay, not overly done as to call attention to itself, but it is there. It is a very seductive sound with the SUT.

SUTs differ though and also depend on properly mating your setup & turns ratio/impedance. That's one reason I like the Lehmann audio. It makes adding a customer parallel resistor to get the right impedance a breeze.


Letsmakeadeal wrote:I headed down the same path a while back and spent some significant money on one of the top SUTs there is. That device was the Coincident Signature. No matter how hard I tried and no matter the interconnect cables there was no way I could eliminate hum. :evil: Belive me, I tried everything. If you purchase an SUT, try to get a money back satisfaction guarantee


So very true. The SUT's I tried all had a money back guarantee.
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Re: SUT or SS LOMC preamp

Postby Jazzgene » Sun Mar 04, 2018 6:48 pm

Edw,

Thanks for the link. I will check them out and perhaps order. My other choice is to get the Miyajima KSW as the unit was designed for the Shilabe/Kansui by Mr. Miyajima himself.

My main amp is a WE91a monoblocks using 300b and Hashimoto OTs. They sound really great and I know Hashimoto has a great reputation.
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Re: SUT or SS LOMC preamp

Postby edw » Sun Mar 04, 2018 9:41 pm

Jazzgene wrote:Edw,

Thanks for the link. I will check them out and perhaps order. My other choice is to get the Miyajima KSW as the unit was designed for the Shilabe/Kansui by Mr. Miyajima himself.

My main amp is a WE91a monoblocks using 300b and Hashimoto OTs. They sound really great and I know Hashimoto has a great reputation.


As the KSW SUT was made your your cart, Id think that it would be a great match.

Yes, the Hashomotos have a great reputation. Besides the HM7, they make other SUTs as well.
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Re: SUT or SS LOMC preamp

Postby Bill Stevenson » Tue Mar 06, 2018 4:32 pm

I see this thread has new life, so thought I would chime in. About a year ago I called and at his recommendation bought a Sky 10 from Bob at Bob's Devices to go with my Conrad Johnson TEA2MAX, 55 db gain. Of several, the cartridge most demanding is an Ortofon Per Winfeld at 0.2mV output. Without the SUT I was not happy with the S/N, but it did work. With the Sky 10 installed at 5:1, it is like magic, open, sweet, quiet. Wonderful! I could not be happier with the result. Thanks Bob!
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Re: SUT or SS LOMC preamp

Postby digitallc » Fri Mar 09, 2018 11:24 pm

edw wrote:Hashimoto/Sansui - http://www.tube-amps.net/




I have the Hashimoto HM-7, and prefer it's sound to the Cinemag 1254 (not made by Bob). Mr Isao Asakura still builds and sells the HM-7, and is very responsive to questions.

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Re: SUT or SS LOMC preamp

Postby edw » Sat Mar 10, 2018 12:22 am

digitallc wrote:I have the Hashimoto HM-7, and prefer it's sound to the Cinemag 1254 (not made by Bob). Mr Isao Asakura still builds and sells the HM-7, and is very responsive to questions.


Yup he built mine too. Classy guy.
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Re: SUT or SS LOMC preamp

Postby DanaFHolmes » Sun Mar 11, 2018 1:58 pm

jmcox wrote:Hi -

I also have a Manley Chinook that I'm using in conjunction with a couple MC carts. Did you find the performance better fed into an SUT then in turn into the 47K load/45db gain the Chinook as opposed to feeding the MC signal directly into the Chinook and utilizing the MC 60db gain of the Chinook? Right now I'm using the Chinook to step up the gain . . . .(??). Improvement with the SUT for gain?


My Chinook sounded way better set at MM 47K with a Bob's Devices SKY 30 then just running the Chinook in MC mode. I am talking like night and day better.
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Re: SUT or SS LOMC preamp

Postby Jazzgene » Tue Mar 13, 2018 2:09 pm

So most feel with a LOMC, it is better with a SUT. I am considering a sut -> tube phono preamp. Many choices out there but leaning towards the Hashimoto SUT.
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Re: SUT or SS LOMC preamp

Postby Bob » Wed Mar 14, 2018 10:38 am

Caveat, This is Bob from Bob's Devices.

Several years ago a group in the Los Angeles area compared the Hashimoto to the 1131 Bob's Devices. Consensus was that the Hashimoto added some smoothing to the sound and colored it a bit. Some said that it sounded a bit fat or bloated. In comparison, the 1131 did not color the sound and it appeared to be more clear and open. Since then, the 1131 was improved with a redesign. The SKY was designed with an unprecedented low inductance to better match moving coil cartridges. The SKY is currently in the Stereophile Magazine A list.
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Re: SUT or SS LOMC preamp

Postby Bob » Wed Mar 14, 2018 10:40 am

Why should you use an external MC step-up transformer into a MM phono stage, versus using a self-contained phono preamp that does it all?

Background: Matching Moving coil Cartridges to phono stages is a difficult process. For MM cartridges it is relatively easy since there is a standard for MM cartridges at 5mV and 47k Ohms. With MC cartridges, there is a wide spectrum of output voltages and internal impedances, as well as a variety of inductances. For a Phono stage manufacturer, it requires some serious design considerations.

Basically, almost all MC phono stages have a MM mode. The designer in most cases, builds a second stage to convert the signal from a MC cartridge to the MM level. Most do this with an active stage designed and built with FETs. Some use internal step up transformers. The challenge is accommodating a wide variety of MC cartridges. This is typically accomplished using a set of switches or jumpers on a circuit board. Many have adjustments for impedance and output voltage (different gain settings). If you look at the specs of each phono stages and compare them for MC cartridges vs. MM cartridges, there is usually a significant different in signal to noise ratio, except for those that use internal step up transformers. For active stages, the ratio is lower by about 8-10dB for MC cartridges vs. MM cartridges. This results in a louder background noise floor for MC cartridges. Additionally, adding switches to low output signals is very difficult to do without degrading sound.

For those phono stages that use internal step up transformers, there is a limited range for MC cartridges and typically, the internal step up transformers are not as good as some of the best in the industry. One step up transformer cannot be made to work properly with most MC cartridges.

A stand-alone step up transformer can be used to better match a cartridge to a MM phono stage, instead of using the internal active stage or the internal step up transformers. You can use a step up transformer ranging from 1:5 to 1:40. For those who say that using a stand-alone Step up transformer is not a good idea because it adds an additional set of interconnects; well, the active stage or internal step up transformers are connected by wires or printed circuits inside the phono preamp. Perhaps one could also say that a console stereo or integrated receiver is better than separates since no interconnects are required. There are many excellent interconnects and connectors that are very transparent.
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