Strain Gauge cartridge at Heathrow Show

I don't understand how you use a "phono" stage without the "pre-amp active gain" ?

What does this mean - quote Bri "but I want a phono with volume control but without the preamp active gain stage" unquote.

and presumably you want an ADC not a DAC ? .... Coops, I presume the MSB does both ?

FWIW, I sometimes just put the cartridge straight into a "mic" input with an appropriate impedance, and do the "eq" in software.

 

Brizon, I passed your query on to Soundsmith and here is the response from Peter Ledermann:

"We have, outputs from the first gains stage -called "fixed"; both positive
and inverted are available for each channel (so you have your choice of
balanced or unbalanced) low impedance outputs that can go directly to
anywhere; a biamp setup (all one needs to do is invert the polarity of one
of the set of drivers to get it back into proper phase). If his gear HAS a
volume control in his biamp gear, then that’s perfect.

We DON’T provide an output from our control as the output from any control
has varying impedance; our volume control is between the first and high
input impedance of the second gain stage, so that the output impedance is
constant from the second stage.
That ultra linear 10 dB ONLY gain stage features the same types of outputs
as the first stage, so it can be used in any number of ways - MAXIMUM
flexibility.

Again, both the first and second stages are available at the rear panel;
positive and inverted, so and each set can be used together, independently,
or in whatever way one would like. If one needs a volume control after the
first stage, and wants to use the SG in that way, there are plenty of good
quality attenuators out there to purchase, and they can be hooked up to the
"fixed" outputs from the first gain stage, assuming there is enough signal
for them to use (0dBm - .775 Volts RMS for normal groove modulation)."

Ralph

 

jcbrum the question relates to the Soundsmith Strain Gauge cartridge system - which comprises a cartridge and a dedicated phono preamp. The cartridge requires a current for the strain gauge sensors to read the modulations in the record groove.

The preamp has two gain stages - the fixed output is taken from the first gain stage and the variable output from the second.

If you plugged this cartridge into a 'mic' input you wouldn't hear anything!

Ralph

 

Coops - my PT Dacapo II has balanced outputs and a volume control so I am not currently looking for a dac. The requirement I described is for a phono stage.

JCBrum - it means a phono stage with a volume control as part of its output buffer stage which can then be connected directly to a power amp, say, without the need for any preamp.

 

Effectively I want the direct fixed option bypassing the additional preamp stage but I do need an attenuator to be incorporated into the phono gain stage. This will feed via a balanced switch into my crossovers. My DAC already has balanced outputs and a volume control. I wish to avoid passive so I dont want to use use a passive attenuator after the first stage. It all depends on the design of the phono gain stage. For instance the PS Audio gain cells have exactly this functionality. Or perhaps the attenuator could be placed before the gain stage in the phono unit?

 

Briz I understand but the MSB is so much better than your da capo, and you can plug the phono directly into the DAC.

 

Coops - I have the DC II not the DC I. As only half a dozen were ever made it seems unlikely you have heard one. You mean to plug the phono into the ADC or to utilise its inbuilt preamp? Either would be inferior to running volume equiped phono stage straight into the crossover unless I am misisng something here.

 

Brizon, I understand where you're coming from and don't disagree with your hypothesis. The manufacturer has been very responsive in coming back with a detailed recommendation of how you could integrate the strain gauge in your system with some good supporting reasons.

If you had heard the Strain Gauge you might not be so quick to reject the manufacturer's suggested options. How about auditioning it?

What's your objection to a passive attenuator? Which models have you considered?

Ralph

 

I have tried TVCs like mfaudio and high quality passive resistive solutions like audio synthesis. None of them match the CDP direct - falling short by a very large margin. I consider preamps to be an unneccesary evil. Souce components can have integrated volume controls as part of the output stage - effectively adding a single extra attenuating component (the benefit of a passive) but without the passive drawbacks as it is part of the output stage, which would be part of the unit anyway. It is the optimal solution.

By way of an example some years ago I compared the brinkmann fein (a "good" phono stage) versus the Groove (a "state of the art" phono stage) via the vibe preamp (a "state of the art" preamp). In this setup the groove was way way better. However as the Fein had a volume control built into its output stage it enabled direct connection to the power amp. In this configuration the fein was so far ahead of the groove / vibe it made the difference observed when both went through the vibe pale into comparison. This illustrates the detrimental effects of even the best preamp stages. Getting rid of any one component in the chain will largely dwarf any other changes you might make. I also conducted comparisons with TVC and resistive passives using my PT dacapo II - going direct using the inbuilt volume control was a revelation even using 10cm cables with preamps like the AS that are supposedly completely transparent.

I dont really need or want a preamp anywhere in my analogue or digital playback chains and have gone to great lengths to avoid it.

No doubt the strain gauage is excellent - but however good it is it will sound better with the 2nd gain stage removed. If the design cannot accomodate volume control via integration in the first gain stage then it doesnt really fit my requirements sadly.

 

What differences did you hear? In what way(s) was it better?

 

In every way - the difference in every area was profound. Its a metaphor I overuse but it was somewhat akin from switching from AM to FM radio. Every aspect of performance was improved significantly. At least as profound than going from a £100 cartridge like a goldring MM to a top of the range MC say.

 

Maybe you should audition the Strain Gauge running from the variable outputs. It sounds nothing like a £100 cartridge or AM radio!

All audio is a compromise - with an MC you lose the speed, agility, tracking and precise imaging of the Strain Gauge and have to live with some magnetic circuit colouration. With the Strain Gauge through the variable outputs I don't think you would be making as big a compromise as that.

I've passed your question on to Soundsmith however the key people have left for a show in Montreal so there may be a delay in response this time.

 

I am sure you are right - it sounds like a great concept.

I dont mean to say any of the systems sounded like a £100 cartridge or AM radio - just that the degree of relative improvement was the same as going from AM to FM.

The improvement of getting rid of the preamp was far bigger than any change in cartridge I have ever heard - unless you go to the real low end. I am currently using a pretty good cartridge (brinkmann emt) so I would estimate the improvement going to the strain gauge would be significantly less than the degradation from adding a preamp. Or even if that was not the case it would still remove most of the benefit due to the magnitude of the preamp effect.

If you have another deck with a conventional cartridge we could compare strain v cartridge using my phono stage through the preamp v cartridge using my phono stage direct into the power amp to demonstrate the issues.

 

Good suggestion. I do have two (well more than that actually) turntables.

I've just come off a call with Mr Ledermann of Soundsmith whilst he's driving to Montreal. We have talked around your query extensively - are you using the Brinkmann Fein currently?

The volume control can't go before the first gain stage for technical reasons we didn't go into. If it goes after the first stage then you have the issue of presenting a variable impedance to your crossovers.

Mr Ledermann commented that the follow-on gain stage is limited to 10 dB with unmeasurably low distortion. In customer evaluations with some very high end preamps, it has always been an improvement to run the variable outputs direct into the power amps ahead of the fixed outputs through the preamp. The implication is the second gain stage does not have the drawbacks of a conventional preamp.

He's back in the office on Monday and is very happy to talk this through with you personally if you wish.

Ralph

 

Hi,

I am about to receive a cullen modified PS Audio GCPH. I have used the Fein previously.

Would it be possible to plumb an attenuator somewhere in the middle of a single gain block? I doubted it could go before - also for reasons of impedance.

It will be easy enough to test his assertion by comparing phono + SG pre versus phono direct for the PS Audio.

What turntable / arm / cartridges do you have available and where are you based?

Feel free to PM me.

Regards,

Nick.

 

Hi Nick

PM to follow. I've just had a look at the PS Audio web site and the two gain stage architecture looks to me like the same concept as used in the Strain Gauge phono pre.

Ralph

 

Hi,

The PS audio has two gain stages as it has to - you need to have one either side of the passive RIAA. The SG only needs one to do what I want so one would be preferable. If a stage can be cut out it should be to get the best sound. Thats the aim rather than a set or comparable number of gain stages.

In addition the PS audio gain cells have adjustable gain control to provide the volume control which is a useful feature.

Regards,

Nick.