I got that point. As far as I know phono stage is a recent lable. Names vary. Doubtless what we call them was the British importers name of the time from the German.
Transformers, a point too easy to forget. We can also invert things with ease. That opens all sorts of possibilities further up the chain.
Transformers, a point too easy to forget. We can also invert things with ease. That opens all sorts of possibilities further up the chain.
Ummm - which particular point?
It's been used for as long as I have had a TT - which is over 4 decades?
AIUI:
* a phono stage - which, yes, is sometimes part of a preamp - amplifies the cart signal and applies the RIAA correction.
* a headamp is a ss (and powered) device which simply amplifies the cart's signal - so an LOMC cart can be used with a MM phono stage.
* as distinct from a SUT - which is another device (but not powered) which amplifies a LOMC's signal so it can be used with a MM phono stage.
And so?
Andy
My opinion is 100% subjective. I tried various combinations with an adjustable gain phono stage and settled on the one that sounded best to me. Now I use a transformer + MC cart as a matter of habit and pick the load by ear.
I have experimented recently with various loads with Benz Micro Gold cartridge in my Pass XOno clone.It has 20 Ohms resistance , 20 microhenries inductance and 0.56 mv output at 5cm. My preferred load so far was 470 Ohms. I switched to 820 Ohm and sound changes I am not sure in which way. Bass was markedly
more focused , mid range more open but harsher , but whole sound was harder to listen and less fluid with harsh trebles and much more record surface noise.I briefly tried 220 Ohm position and it gave less defined bass and warmer vocals which is probably pleasant coloration.My conclusion was that MC cartridges with voltage amplification are not able to give neutral sound due to loading resistance.Just personal preference. Transimpedance, current amp. phono stages are not so popular. Members of this forum probably know why. My next step will be to adapt my Borbely 419 phono stage to current amplification and eliminate loading resistors.Or return to my old Shure VST-V MM cartridge. With right C loading which is not difficult, MM cartridges coils are not influenced by loading resistance in the same way as MC .
more focused , mid range more open but harsher , but whole sound was harder to listen and less fluid with harsh trebles and much more record surface noise.I briefly tried 220 Ohm position and it gave less defined bass and warmer vocals which is probably pleasant coloration.My conclusion was that MC cartridges with voltage amplification are not able to give neutral sound due to loading resistance.Just personal preference. Transimpedance, current amp. phono stages are not so popular. Members of this forum probably know why. My next step will be to adapt my Borbely 419 phono stage to current amplification and eliminate loading resistors.Or return to my old Shure VST-V MM cartridge. With right C loading which is not difficult, MM cartridges coils are not influenced by loading resistance in the same way as MC .
Sorry to not be up to speed with namings.
One thought that comes to mind. One can have the option of common base in phase output and the more used common emitter out of phase output when MC. Time was the the common base amplifer was held to be a bit magical. To my mind common emitter has an interesting advantage or two. It will if conditions are right allow an inverting op amp stage to follow. The larger advantage of this is the noise levels should be lower. As LP's are not low distortion sources a little more experiment than usual is OK.
Lentek had a circuit which was called a heap amp ( I think ). This is said to be it. It was a special device, nothing like Audiolab which is said to be the same designers.
One thought that comes to mind. One can have the option of common base in phase output and the more used common emitter out of phase output when MC. Time was the the common base amplifer was held to be a bit magical. To my mind common emitter has an interesting advantage or two. It will if conditions are right allow an inverting op amp stage to follow. The larger advantage of this is the noise levels should be lower. As LP's are not low distortion sources a little more experiment than usual is OK.
Lentek had a circuit which was called a heap amp ( I think ). This is said to be it. It was a special device, nothing like Audiolab which is said to be the same designers.
In the "Optimal cart loading with a SUT" thread that Pieter T complained about my input on, all the maths was about the 'R' loading for an MC. The SUT reduces the default load in the phono stage by the square of its turns ratio - so for a 1:10 SUT, 47K is seen by the cart as 470 ohms ... which might be fine for some carts.
And - if your cart prefers a lower value, you can reduce this by putting the appropriate-value resistor across the output terminals of the SUT (so it acts in parallel to the 47K to bring down this value).
And if you want to be even more precise, you can include the effect of the primary & secondary coil windings.
It so happens I have been going through various posts and articles that I have collected over the past 30 years and I found an email from Jim Hagerman from 2003, which talked about the effect of a SUT:
* not only does it reduce the value of the phono stage's input R-load by the square of the turns ratio but
* it also increases the phono stage's input C-load by that same factor!
So a phono stage with a 100pF input capacitance presents itself as a 0.01uF capacitance load, in the case of a 1:10 SUT. Not all carts would like this.
And in the case of a 1:20 SUT ... you are looking at an input capacitance of 0.04uF (if the phono stage uses 100pF)! Not many carts would like this.
And in the case of someone with a 1:32 SUT that I was conversing with recently ... the number is 0.102uF. Which is very high.
This, I suggest is a big - but almost unknown - downside of a SUT.
Andy
And - if your cart prefers a lower value, you can reduce this by putting the appropriate-value resistor across the output terminals of the SUT (so it acts in parallel to the 47K to bring down this value).
And if you want to be even more precise, you can include the effect of the primary & secondary coil windings.
It so happens I have been going through various posts and articles that I have collected over the past 30 years and I found an email from Jim Hagerman from 2003, which talked about the effect of a SUT:
* not only does it reduce the value of the phono stage's input R-load by the square of the turns ratio but
* it also increases the phono stage's input C-load by that same factor!
So a phono stage with a 100pF input capacitance presents itself as a 0.01uF capacitance load, in the case of a 1:10 SUT. Not all carts would like this.
And in the case of a 1:20 SUT ... you are looking at an input capacitance of 0.04uF (if the phono stage uses 100pF)! Not many carts would like this.
And in the case of someone with a 1:32 SUT that I was conversing with recently ... the number is 0.102uF. Which is very high.
This, I suggest is a big - but almost unknown - downside of a SUT.
Andy
How about a transformer in between active stages if throwing money about? Valve guys do this. It can for them be the highly desirable Ultra Linear type having a centre tapped winding to g2, higher gain and linearity over triode. For the engineering advantages use a valve as they are not the worlds worse voltage amps.
If a transistor can be made to be a current amplifier it also should be device of first choice. Maybe don't ask it to be a I to V converter.
As far as I can see the major adantage of a transformer is to force more current to do more work from an MC pick up. If we load the output that should give the reflected input load ( 47K = circa 100R at gain of 20 ). If that load is eqaul to the coil resistance we " might " be at current Zenith. We also filter RF nasties a bit so get a bonus.
From my experiance MC loading is to suit the preamp. Sure it sounds different, is that for the reason you guess? With MM it is more complex and is each has it's own merrit. Shures really like 1M if you can re EQ, try 100K first .
If you build a really good preamp don't be surprised if all loadings with MC sound the same. One cartridge is said to like only 845R. I really don't know.
If a transistor can be made to be a current amplifier it also should be device of first choice. Maybe don't ask it to be a I to V converter.
As far as I can see the major adantage of a transformer is to force more current to do more work from an MC pick up. If we load the output that should give the reflected input load ( 47K = circa 100R at gain of 20 ). If that load is eqaul to the coil resistance we " might " be at current Zenith. We also filter RF nasties a bit so get a bonus.
From my experiance MC loading is to suit the preamp. Sure it sounds different, is that for the reason you guess? With MM it is more complex and is each has it's own merrit. Shures really like 1M if you can re EQ, try 100K first .
If you build a really good preamp don't be surprised if all loadings with MC sound the same. One cartridge is said to like only 845R. I really don't know.
in the case of someone with a 1:32 SUT that I was conversing with recently ... the number is 0.102uF. Which is very high.
This, I suggest is a big - but almost unknown - downside of a SUT.
Andy
I think typical LOMCs have inductances measured in the uH range which would center the filter well above audio. Even at 100uH which I think is 10x higher than expected you are looking at around 1dB and 5 degrees of phase shift at 20kHz
In the "Optimal cart loading with a SUT" thread that Pieter T complained about my input on, all the maths was about the 'R' loading for an MC. The SUT reduces the default load in the phono stage by the square of its turns ratio - so for a 1:10 SUT, 47K is seen by the cart as 470 ohms ... which might be fine for some carts.
And - if your cart prefers a lower value, you can reduce this by putting the appropriate-value resistor across the output terminals of the SUT (so it acts in parallel to the 47K to bring down this value).
And if you want to be even more precise, you can include the effect of the primary & secondary coil windings.
It so happens I have been going through various posts and articles that I have collected over the past 30 years and I found an email from Jim Hagerman from 2003, which talked about the effect of a SUT:
* not only does it reduce the value of the phono stage's input R-load by the square of the turns ratio but
* it also increases the phono stage's input C-load by that same factor!
So a phono stage with a 100pF input capacitance presents itself as a 0.01uF capacitance load, in the case of a 1:10 SUT. Not all carts would like this.
And in the case of a 1:20 SUT ... you are looking at an input capacitance of 0.04uF (if the phono stage uses 100pF)! Not many carts would like this.
And in the case of someone with a 1:32 SUT that I was conversing with recently ... the number is 0.102uF. Which is very high.
This, I suggest is a big - but almost unknown - downside of a SUT.
Andy
I would advice to read a bit more into the subject instead of spreading nonsense.
This is a good read wrt cartridge-SUT-preamp interface:
http://www.diyaudio.com/forums/diya...oise-thoroughly-modern-tube-phono-preamp.html
With modern MC cartridges, quality SUT's and well designed phono preamps, capacitance is not an issue.
I am curious with what you might come up next time
.I would advice to read a bit more into the subject instead of spreading nonsense.
This is a good read wrt cartridge-SUT-preamp interface:
http://www.diyaudio.com/forums/diya...oise-thoroughly-modern-tube-phono-preamp.html
With modern MC cartridges, quality SUT's and well designed phono preamps, capacitance is not an issue.
I am curious with what you might come up next time
Very interesting article link, Pieter. Thanks. If you desire a tube phono stage then you could do a lot worse than what Stuart did.
But the view put forward by Stuart is that of a 'tubophile'; while I love what tubes can do ... in a phono stage, I myself prefer to use JFETs. And (for noise reasons) run them off SLAs. About 3 years ago, I was lucky enough to be able to compare v3 of my 'Muse' phono stage, as I call it, against the Brinkman 'Edison' - which I'm sure you know of. The Muse came 2nd in the comparison ... but only by a small margin. As I charge $1,300 for the Muse, I thought that was a good result - given the then-price of the Brinkman in Australia was $15,000. Re. "spreading nonsense" I don't see it that way - I'm simply putting forward a different way of thinking.
You are perfectly free to hold the view that "With modern MC cartridges, quality SUT's and well designed phono stages, capacitance is not an issue" ... I hold a different view. What I am pretty sure about, though, is that most folk who have a tube MM phono stage and want to run a LOMC with it ... don't compare the sound resulting from using a good SUT to using a good headamp.One that has is a customer of mine (who caused me to buy 5x 'Paris' kits off Hugh Dean) who was running his Benz LP into a high priced, well regarded US-made tube phono stage which uses a 1:10 SUT for the MC input. And so was listening to his LP loaded at 470 ohms.
I lent him my own Paris - which I'd built in the mid-2000s - with a collection of loading resistors, so he could listen to his LP through the MM input of the phono stage, with different loads applied. He made the comparison against the inbuilt SUT - and realised how much better the LP sounded, loaded at several thousand ohms ... so he asked for a 'Paris'.
Regards,
Andy
I am OK with your (subjective) preference for headamps over SUTs, but please stick to facts: the second quote above is complete nonsense. It's difficult to take you serious this way.
Transformers have ratios which treat voltage and current, and they can act to match source and load impedance wise. They don't treat capacitance that way.
Pieter - as I said earlier in my post #27, I found (in my files) a printed email from Jim Hagerman, from 2003 (which I had forgotten about for 14 years), which said that SUTs used in front of a MM phono stage:
* yes, decrease the 'R' loading of the MM phono stage
* but increase the 'C' loading acting on the cartridge.
Now, you may be aware that Jim H is considered to be a guru of things phono - in particular, cart loading. So if he says something ... I believe it.
Regards,
Andy
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No I don't think that is what Jim is saying at all.
My take on what he said is that whatever capacitance is present at the input of an MM phono stage - which can be produced by:
* either a cap in parallel with the 47K input R-load
* or by the Miller capacitance of the 1st gain stage
... will be multiplied by the square of the turns ratio of the SUT.
Andy
Andy, my 2 cents - if you want the best outcome, why don't you just design a phono stage amp that is suitable for m-c cartridges? Why would you build an amplifier that will not work with m-c cartridge, then build another amplifier to put in front of it?
Here is what I use. 2 gain stages, all in one RIAA. In my build I have included variable input impedance (100ohmto 1.4kohm). Output for my Lyra cartridge (about 0.5mV) is 2 volt, however i have implemented adjustable gain via a variable resisitor across the output. All the flexibility you want in one amplifier. And its balanced so its quiet as, no need for high capacitance shielded cabling. Well, my power amps are balanced so I do prefer balanced sources in any case.
I don't have a view on SUT vs head amp because I would never build 2 amps when a simple design can do it in one. Actually since I have variable gain in my Phobos, I don't even use a pre-amp, so it is reasonable to say that I have replaced 3 amplifiers with one amplifier. Do you use a pre-amp? If so, why? Its just another redundant box.
And yes I have different phono stages for my strain gauge cartridges, and my m-m cartridges. This is DIY audio, why not? I can understand that the average consumer will not want 3 different phono stages but its very easy when you can make them yourself.
http://www.diyaudio.com/forums/analogue-source/289428-phobos-balanced-mc-phono-stage.html
Here is what I use. 2 gain stages, all in one RIAA. In my build I have included variable input impedance (100ohmto 1.4kohm). Output for my Lyra cartridge (about 0.5mV) is 2 volt, however i have implemented adjustable gain via a variable resisitor across the output. All the flexibility you want in one amplifier. And its balanced so its quiet as, no need for high capacitance shielded cabling. Well, my power amps are balanced so I do prefer balanced sources in any case.
I don't have a view on SUT vs head amp because I would never build 2 amps when a simple design can do it in one. Actually since I have variable gain in my Phobos, I don't even use a pre-amp, so it is reasonable to say that I have replaced 3 amplifiers with one amplifier. Do you use a pre-amp? If so, why? Its just another redundant box.
And yes I have different phono stages for my strain gauge cartridges, and my m-m cartridges. This is DIY audio, why not? I can understand that the average consumer will not want 3 different phono stages but its very easy when you can make them yourself.
http://www.diyaudio.com/forums/analogue-source/289428-phobos-balanced-mc-phono-stage.html
Absolutely, H500!
But so many people buy an MM phono stage and an MM cart ... and then decide they want to try an MC cart ... so they need some way of amplifying the LOMC signal to MM levels. And if they have a tube phono stage - they automatically choose a SUT for this amplification (because they don't know any better! ).I do actually build 2 versions of my 'Muse' - one for MMs and one for MCs. I can adjust gain to a limited extent for each of these:
* MM - from 40 to about 46dB, and
* MC - from 50 to about 60dB
Very cool, Similar to mine except in my case, variable input impedance is done by having parallel input RCAs, so you can use load plugs to bring down the default R and C values to whatever your cart prefers. I provide this on the MM version as well as the MC version, because MMs like different cap loadings and some like something other than 47K resistance loading.
But it is not balanced.
I do use a preamp - as this provides me with:
* source selection, and
* volume control.
Regards,
Andy
Ah you are a guru-believer, even if the guru is wrong
That makes the discussion not easier.
Jim H mentions SUT's in his article; nowhere I see this incorrect statement wrt capacitance.
Now you change your statement: instead of "increasing C-loading by the square of the winding ratio", it's now "increasing C-loading acting on the cartridge".
Of course there is extra capacitance involved when using a SUT; however the very low self inductance of the MC cartridge deals with it perfectly.
A good MCcart-SUT-preamp interface yields a bandwidth reaching up to 150 kHz, enough for most of us....
Curious if you could come up with a copy of that illustre printed email; I might have overlooked something during the last twenty years
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As I said, Pieter, the information I quoted (about a SUT increasing whatever capacitance is at the input of the phono stage) came from a private email from Jim - not Jim's paper on cart loading.
Curious if you could come up with a copy of that illustre printed email; I might have overlooked something during the last twenty years
It would be very easy for me to do this, Pieter - simply scan the printout of the email which I have kept ... and include it in my post.
But I will not be going this because it was a private email - and, in my world anyway, one does not make private emails available to the general public.
If you really did want to delve deeper into this issue ... you could always email Jim yourself and ask him his opinion of whether SUTs increase C-loading, at the same time as decreasing R-loading.
Me - given I had forgotten about Jim's comment until just the other day - it reinforces my belief that I am on the right track when I espouse headamps, rather than SUTs. Andy
Let's be clear:
- SUT's increase C-loading, however not the way you stated initially;
- SUT's decrease R-loading, giving the opportunity to load MC carts correctly.
I am having no problems with promoting headamps over SUT's; it becomes nasty when false statements come into play.
- SUT's increase C-loading, however not the way you stated initially;
- SUT's decrease R-loading, giving the opportunity to load MC carts correctly.
I am having no problems with promoting headamps over SUT's; it becomes nasty when false statements come into play.
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