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In the Forum: Analog Playback
In the Thread: The Expressive Technologies SU-1
Post Subject: Re: The "bad" S&B resellers...Posted by Thorsten on: 1/24/2005

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 Antonio J. wrote:
MFA e-mailed me aknowledging that I was perhaps going to try the DIY way getting a "raw" transformer from S&B and offered me assistance. The "problem" is that their unit with a gain selector and load selector is way too expensive for my budget (1500 UKP), while the raw transformers are about 250 euros each.


The fully build stepup is priced for retail distribution in your local shop. As such it has dealer and distributor profit margins build and is a product build with general compatibility in mind etc. For anyone who can solder well and who does not mind the absence of a "finished product" finish the raw transformers are available too. You might be surprised to know that MF-Audio actually does make proportionally to the work required makes about the same income as S&B does for a TX-103 and JB is not getting rich from it.

One might also consider that the nearest competitor, namely the EAR MC3 Stepup costs more than 1/2 of the MF Audio unit and offers less adjustability, the sound has been commented on elsewhere.

 Romy the Cat wrote:
Antonio, I never understood this concept of “gain selector”.


It is not a "gain selector" as much as it is a selector to match the cartridge source impedance. Very low impedance cartridges (many modern MC's) should be used on the highest stepup setting (1:20/26db), as that matches the transformers operation correctly. On the other hand, MC's like the Denon DL-103 do not sound under such conditions as their internal impedance is much higher, so they should be connected ideally with the lowest stepup (1:5/14db) as that matches the impedances best.

Failure to match impedances well will invariably colour the sound, I would say worsen it.

 Romy the Cat wrote:
If I remember correctly S&B had 10, 20 25 db options via re-wiring of the primary coil. It is not complicated to place primary in some kind of rotary 3-position switch but it would be completely unnecessary.

 
I disagree. In order to be able to get the best out of an expensive cartridge and stepup one MUST have the ability to both match the input connection of the transformer and to apply varying loads.

The normal approach to handeling primary impedance matching is to use multiple taps on the primary and to simply leave the unused part of the primary unconnected. That usually impacts on the sound and not in a positive way.

Therefore the MF Audio Stepup (which you might call my design if you so wish) has a Selector for the input connections and for loads down to the nominal 10K secondary impedance.

 Romy the Cat wrote:
Presumably all those aftermarket S&B resellers try to convince buyers that by they would “have a flexibility to select a gain whatever they wish” but I find that it is quite a bogus benefit.


No, the point is actually that unless you wish to actually design a transformer specifically for a given cartridge you must be able to select the correct primary impedance OR you must accept sonic losses, which BTW are by far greater than the ones caused by the switch.

 Romy the Cat wrote:
Fist: it is VERY difficult to fine a switch that would commutate 0.3mV signal without any sonic degradations (at list I was not able to find any).

 
Maybe. The switch that is used proved itself sufficiently transparent that there was in several systems, including much more elaborate ones than my own, no material degradation between a hardwired and a switched version.

 Romy the Cat wrote:
Second: people need one permanent gain for one given cartridge/phonocorrector and no one doing the switching after a necessary gain was found (people who use multiple needles and multiple arms usually have multiple phonocorrectors).

 
Yes, you need only one primary impedance and one gain and one load for a given combination. However, if you alter this combination you need to change. I felt giving users the ability to do this change direct and for themselves is of value.

 Romy the Cat wrote:
Therefore, if you’re willing to use S&B then get them raw and considering that the cable between the transformer and phonostage is the most critical of all then just mount those S&B directly to the binding posts of your phonocorrector. The S&B despite of very simple mu-metal can are quit quiet and it can easily work in this application.

 
I agree. However there are enough people who refuse even to consider something where they may need to take the lid off in order to adjust something.

 Romy the Cat wrote:
I would go for 20-25db and then just tune the loading resistor.


I would choose a primary connection that is actually apropriate to the internal impedance of the cartridge, eg. for Cartridges in the 3-10R region 1:20, for those in the 10-30R region 1:10 and for pickups above 30R 1:5.

 Romy the Cat wrote:
To have those “luxury” options that Bent Audio and few other offers I find not only unnecessary but also “bad for sound”.


Sorry, but in order to make that call you would have had to have compared an MF-Audio Stepup to a hardwired 103, which you have not done. We have done it and found the sonic impact rather slight, if notable on VERY CRITICAL audition.

Ciao T

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