Moving coil via Croft 25R Pre

[Jimbo]

I may be considering a MC cartridge as I have recently heard the absolutely superb Dynavector Te Kaitora using my Turntable and to be honest it gave about twice the SQ abilities of my 2M Black, although it was 4 times the price!

However I would like to run a Moving coil cartridge with my Croft 25R pre which is obviously only MM compatible.

What would I need to use to get the very best out of a MC cartridge via my Croft linestage? A SUT or MC phono stage?

Sorry I am a bit ignorant in this area having never used a MC cartridge, hence the request for AOS help:)

[Riislingen]

You would need a SUT matched to the cart for best performance IMO.

[walpurgis]

You're going to get all sorts of opinions on this one James.


I've always favoured a good MM phono stage with a decent SUT. I've been using MCs that way with various amplifiers for over thirty years.

I've tried a lot of MM phono stages. In the last few years I've gone from an EAR 834P valve stage to a solid state Graham Slee ERA Gold V and am currently running a Graham Slee Reflex M.

My SUT is an unobtainable Osawa unit!

[Jimbo]

You're going to get all sorts of opinions on this one James.


I've always favoured a good MM phono stage with a decent SUT. I've been using MCs that way with various amplifiers for over thirty years.

I've tried a lot of MM phono stages. In the last few years I've gone from an EAR 834P valve stage to a solid state Graham Slee ERA Gold V and am currently running a Graham Slee Reflex M.

My SUT is an unobtainable Osawa unit!

Please excuse my ignorance but how does a MM phono stage differ from a SUT?

[walpurgis]

MM cartridges have higher output than MCs as a rule so the input sensitivity of an MM phono stage does not have to be as high as one for low output MCs. An SUT is a transformer unit that steps up the output of low output MCs sufficently to drive an MM stage.

[Ali Tait]

The same job can also be done with a head amp, which can also give great results.

[Jimbo]

MM cartridges have higher output than MCs as a rule so the input sensitivity of an MM phono stage does not have to be as high as one for low output MCs. An SUT is a transformer unit that steps up the output of low output MCs sufficently to drive an MM stage.

Sorry Geoff, I meant to ask how does a Moving Coil Phono stage differ from an SUT?

[Ali Tait]

A SUT is just a transformer.

[walpurgis]

Sorry Geoff, I meant to ask how does a Moving Coil Phono stage differ from an SUT?

A moving coil phono stage has higher gain than an MM unit and therefore the 'boost' provided by an external SUT is not needed. Some MC phono stages have SUTs built in, others use circuitry to do the same job.

[Firebottle]

As a picture is worth a 1000 words, I have done a little sketch to show all the combinations of MC operation, for those that are a little unsure.

http://i601.photobucket.com/albums/tt97/Paramotorpilot/P1040676.jpg

The last two show when the SUT is built in to the MC stage, or when built in additional circuitry provides the necessary gain, typically a JFET cascode circuit or low noise op-amp.

:cool: Alan

[hifi_dave]

You have a great phono stage built into your Croft 25R and unlikely to equal it at many times the cost. You just need a GOOD step-up transformer or a head amp, which are rare beasts.

If you want an excellent transformer, the RFC MC-1 is very reasonably priced and for a head amp, the Albarry MCA-11 is the kiddie.

[Jimbo]

You have a great phono stage built into your Croft 25R and unlikely to equal it at many times the cost. You just need a GOOD step-up transformer or a head amp, which are rare beasts.

If you want an excellent transformer, the RFC MC-1 is very reasonably priced and for a head amp, the Albarry MCA-11 is the kiddie.

I think this would be the route for me Dave, a good SUT.

Would the SUT be connected via the phono inputs or linestage inputs on the Croft pre?

[hifi_dave]

The phono stage not only amplifies the tiny signal from your cartridge but also applies equalisation necessary for a balanced sound. The step up transformer or head amp just applies matching for the moving coil cartridge and also boosts the signal a bit more, so that it drives the phono stage properly. Without a step up transformer or head amp, the moving coil cartridge will not drive the phono stage properly and you will have insufficient volume.

Therefore, yes, the SUT connects to the phono stage on the Croft and not a line input.

[Jimbo]

The phono stage not only amplifies the tiny signal from your cartridge but also applies equalisation necessary for a balanced sound. The step up transformer or head amp just applies matching for the moving coil cartridge and also boosts the signal a bit more, so that it drives the phono stage properly. Without a step up transformer or head amp, the moving coil cartridge will not drive the phono stage properly and you will have insufficient volume.

Therefore, yes, the SUT connects to the phono stage on the Croft and not a line input.

So i get the benefits of using the fabulous Croft phono stage:) Thats what i'm after. I suppose the other option would be to ask Glenn if he would kindly build in a MC stage but not sure if this is that easy as difficult to get quiet enough valves.

Think SS SUT via phono stage would work very well. I am thinking of Dynavector MC cartridge which is very low output so finding a suitable SUT will be critical.

[worrasf]

I may be considering a MC cartridge as I have recently heard the absolutely superb Dynavector Te Kaitora using my Turntable and to be honest it gave about twice the SQ abilities of my 2M Black, although it was 4 times the price!

However I would like to run a Moving coil cartridge with my Croft 25R pre which is obviously only MM compatible.

What would I need to use to get the very best out of a MC cartridge via my Croft linestage? A SUT or MC phono stage?

Sorry I am a bit ignorant in this area having never used a MC cartridge, hence the request for AOS help:)

Hi James - after you have read and digested all the good advice above - if you are interested I have a Dynavector SUP-200 SUT for sale. Being Dynavector it would be a perfect match for the Dynavector cartridge you are interested in.

It's currently listed on eBay at: http://www.ebay.co.uk/itm/171618443800?ssPageName=STRK:MESELX:IT&_trksid=p3984.m1555.l2649

Steve

[hifi_dave]

So i get the benefits of using the fabulous Croft phono stage:) Thats what i'm after. I suppose the other option would be to ask Glenn if he would kindly build in a MC stage but not sure if this is that easy as difficult to get quiet enough valves.

Think SS SUT via phono stage would work very well. I am thinking of Dynavector MC cartridge which is very low output so finding a suitable SUT will be critical.

Glenn is most definitely not a MC fan, which is why he doesn't make any MC phono stages. One of the problems is noise induced into the extra gain stage needed for a MC. A separate step up transformer or head amp is the way to go. As I mentioned earlier, RFC make an excellent and very reasonably priced step up transformer. Another good choice would be the Dynavector from Steve.

[Jimbo]

Glenn is most definitely not a MC fan, which is why he doesn't make any MC phono stages. One of the problems is noise induced into the extra gain stage needed for a MC. A separate step up transformer or head amp is the way to go. As I mentioned earlier, RFC make an excellent and very reasonably priced step up transformer. Another good choice would be the Dynavector from Steve.

Funny that,I was just looking at Steves SUT on ebay.

Thanks for the help chaps, at least now i know what my options are and the best way for me to use a MC cartridge with my Croft set up.

Will have to save up a few more pennies as moving to a MC does not come cheap:rolleyes:

[hifi_dave]

No, moving-coil done properly isn't a cheap option. A decent MM will sound better than a good, expensive MC played through an indifferent phono stage.

[Sondekker]

For what it's worth, I currently use a MC (Lyra Delos) via a SUT into a Croft 25R having made the move from previously using a variety of MC phono stages for many years.

I agree with others that a good SUT driving a MM phono stage can offer excellent sound quality. In the last year I have tried a Rothwell MCL, A Reference Fidelity MC1 and a Bob's Devices Cinemag into my Croft and all have provided excellent results. All these SUT's retail around the £500 mark and all sound slightly different. I settled on the Cinemag finding it offered a slightly deeper and fuller presentation than the others in my system and I also liked its ability to switch between two gain options.

It can be great fun experimenting although the one downside is that good SUT's are not cheap. I've always yearned to hear some of the really top quality (and really expensive) SUT's in my system in order to see what further improvements can be had.

[walpurgis]

Glenn is most definitely not a MC fan, which is why he doesn't make any MC phono stages. One of the problems is noise induced into the extra gain stage needed for a MC. A separate step up transformer or head amp is the way to go. As I mentioned earlier, RFC make an excellent and very reasonably priced step up transformer. Another good choice would be the Dynavector from Steve.

Is that really the case? Seems a pretty blinkered point of view, if true. Other manufacturers manage to offer decent MC facilities, so it can't be an insoluble problem. I don't see the logic in a well known amplifier maker not catering to the large number of MC users.

[worrasf]

Is that really the case? Seems a pretty blinkered point of view, if true. Other manufacturers manage to offer decent MC facilities, so it can't be an insoluble problem. I don't see the logic in a well known amplifier maker not catering to the large number of MC users.

Maybe I can shed some light on this as I am one of the (I suspect) very few folk who own and use a Glenn Croft MC headamp. These are as rare as rocking horse manure and I was really lucky to find it in (according to Glenn) as new/unused condition. I discussed it at length with Glenn and the reason he stopped production (alluded to by hi-fi dave) is the problem of noise that can come with the gain required. Glenn's view was that nowadays virtually none of the readily available "affordable" valves (it uses E88CC's) are quiet enough. I have tried several sets of valves - the ones it came with (no name Colomore) were OK but a tad noisy if the volume was up a bit - the second best I have found are NOS Phillips Miniwatt E88CC SQ gold pins (lovely "liquid" midrange) but the uber best are my NOS NIB Siemens & Halske CCA's - these are almost as rare as the headlamp itself and not cheap but with them inside the Croft MC headamp sounds sublime into my Croft 25R/7 monoblocks.
Steve

[Firebottle]

£500 for a SUT strikes me as a very expensive way of going about it.

OK I've got the advantage of my technical understanding and design skills, but what the Croft needs is an add on 'stage' that can just be plugged in.
This has me thinking now, with just a couple of extra phono sockets, a very minor internal re-wire and an MC module the Croft could have MC capability.

The price difference between my MM and MC is only £100.................:mental:

[Jimbo]

£500 for a SUT strikes me as a very expensive way of going about it.

OK I've got the advantage of my technical understanding and design skills, but what the Croft needs is an add on 'stage' that can just be plugged in.
This has me thinking now, with just a couple of extra phono sockets, a very minor internal re-wire and an MC module the Croft could have MC capability.

The price difference between my MM and MC is only £100.................:mental:

Now Alan thats more like it - just what i was thinking, if Glenn does not make a SUT or MC Module, I know a man who can.

Would this be a linestage module or would it use the Croft phono stage?

[Firebottle]

This would use the Croft phono stage, you already have 80% of what's needed for MC. It is only gain that is lacking, plus the right input impedance but that bit is trivial.

The extra 20% is the bit that would convert the Croft first stage to a cascode stage, plus with two sockets this could be made 'plug and play' with the original biasing components.

This would enable existing operation with the MM input; remove two 'biasing plugs' and connect the MC module and you have a separate MC input, simples?:mental:

:) Alan :)

[Jimbo]

This would use the Croft phono stage, you already have 80% of what's needed for MC. It is only gain that is lacking, plus the right input impedance but that bit is trivial.

The extra 20% is the bit that would convert the Croft first stage to a cascode stage, plus with two sockets this could be made 'plug and play' with the original biasing components.

This would enable existing operation with the MM input; remove two 'biasing plugs' and connect the MC module and you have a separate MC input, simples?:mental:

:) Alan :)

This sounds a simple solution Alan. Do you think the stage will be quiet or does this depend on the current valves used in the phono stage?

[Firebottle]

No reason at all why it wouldn't be quiet, the ECC83 is a quiet valve.

:cool: