Dear Almandog, by altering the load resistance of a MC-cartridge you do alter the level of feedback. When going down with the load resistor you do increase the feedback and the bass will ever tighten up and the whole sound do get more controlled (which can get pretty worse....).
In the whole discussion about cartridge loading one very important aspect is sadly forgotten and often neglected: the source impedance of a MC-cartridge is but only ONE of TWO important factors determination the correspondent partner (phono input stage or mc-step-up transformer).
The other one is the inductance.
You need matching impedance AND matching inductance.
Its the very same as with all coil-based transducers in the audio-chain (your speakers (...the drivers coils and the coils in the x-over ...) and the output-stage of the amplifier are the other "link") - inductance AND resistance.
A point often discussed and never neglected in amplifier/speaker design.
Thats why a perfectly matched step-up transformer does always MORE for a given MC cartridge as any high gain phono stage.
The high gain phono stage sans transformer has always some difficulties offering the MC-cartridge the requested and expected matching inductance......... |
Dear Lewm, any moving coil cartridge does have a coils whose movement in a given magnetic field gives the output. This coil (singular - as we are looking at one channel now...) has a source impedance - that is the parameter everybody knows about and does care about. So far so good. However - any coil does have an impedance AND an inductance.
So you have TWO source parameters.
Everybody does care about the matching load resistor in the following stage to match the source impedance.
Hardly anybody does care about the 2nd parameter - the matching inductance of the following stage.
We agree about the source impedance calling for a matching load impedance.
So far so good - that is ONE parameter.
But your cherished moving coil is also calling for the matching load inductance.
Sadly this desperate call and longing is hardly ever heard...... let alone satisfied.
If you are using a step-up transformer, you do get the matching inductance as a "freebee" with the matching impedance, as the impedance in a step-up is a result of coil-windings - as is the source impedance and source-inductance of your MC cart.
Loading a given MC cart with different resistors does alter the sound. The more so, as the resistor becomes very small. Why ? - Because you increase the amount of feedback applied on your cartridge circuit.
A suitable - yet often abused way to adapt your cartridges sound to the audio-chain it is already part of.
A cartridge of overall sound lacking bass impact and control - simply load down the beast and - รจ voila! - here we go with a surprisingly tight bass line!
But the mid-range magic is gone and the sound is somewhat lifeless........
This is what happens all too often.
Back in the late 1980ies I thought a step-up transformer was a waste of time and quality - high gain phono stage and one link less in the chain.
Wrong.
Only (sorry......) a matching step-up transformer does offer the ideal matching (technically spoken) next and first amplification stage for ANY low-output moving coil cartridge.
As any high gain active phono stage can offer adjustable load resistor - but hardly an adjustable inductance.....
So - you are looking for the "perfect" match for your moving coil cartridge ?
It is a matching step-up transformer.
The ideal type depends on your MCs output and its source impedance and corresponding inductance.
Its that easy.
If you have the REALLY matching transformer, load resistors are no longer any discussion. Its a natural match.
All this was no question in the late 1950ies when the first low-output moving coils were introduced.
The abundance of step-up transformers being an integral part of the moving coil based phono front-end came, when the high gain phono stages emerged in the late 1980ies. |
Lewm, - a further add-on to my earlier statement and more direct in answer to your questions.
- the mismatch between the source impedance and inductance of the moving coil cartridge with the following amplification-stage does result in a NOT optimum performance. This may and will mean the frequency response, as well as dynamics, timbre, most likely soundstage reproduction (= low level resolution).
- the matching inductance is only correctly obtained with a matching coil as following stage.
- I would not try to simulate the inductance with a wire-wound resistor.
Nor would I add an inductor in series.
Depending on the circuit and principle, your phono input stage may not like the idea at all.
I like looking at technical aspects in the most straightforward and "natural" way. The concept of a moving coil cartridge does longing for -and ask for - a matching first amplification stage in the form of a matching coil - a step-up transformer.
Here - and only here - he find the natural corresponding partner with exact the technical periphery and resulting inductance and impedance needed to ALLOW the moving coil cartridge to perform at its optimum.
Give it a try.
There are good reason why - even given today's high gain phono stages - there are still a lot of step-up transformers around.
Just get a good one which does match the requirements of your given moving coil.
It may open up ears and eyes.
Thanks. |
Atmasphere, I took the term "feedback" for good reason.
It illustrates nicely what happens when the MC cartridges gets "loaded down" into the 10 - 30 Ohms region and gives a nice idea too about the sound you may expect to get.
The point of inductance matching in moving coil cartridge and the following step-up transformers was throughout explained and discussed when you and I weren't even born yet.
I can only recommend to every audiophile really interested to get the most out of his moving coil cartridge to give it a try with a high-class (Jensen Transformers is indeed a very good address...) step-up transformer with a suitable step-up ratio (not too high...).
The resulting sound will proof that there is more than just correct resistance loading to get the full and real sound of a high-class low output moving coil........ |
Atmasphere, apparently you totally miss my point - your initial two sentences in your last post seems to imply that...
Anyway - I have built, bought, had and still have active phono stages with gain up to 78 dB. Suitable for almost everything the cartridge industry has ever produced.
Tube based and J-Fet based.
Hybrids too.
All very quiet - you would be happy (and surprised...) with any of them.
Lets further assume, that my playback system is the sonic equal of anything - for any price tag - the industry has (or had) to offer ;-)...
Lets assume further, that I am not deaf.
Lets assume even further that I do have a very precise idea about live-like sound and what REALLY is possible in analog-playback and have (big surprise....) the tools and (even bigger surprise...) the skill to get what I want.
Based on all those assumptions I am favoring a GOOD (wide range...) and WELL-CHOOSEN (skill-depending...) step-up transformer not out of despair or lack of gain.
I favor it because I know and have heard often enough its benefits vs an active gain stage.
That your experience is different is fine with me.
Everybody has and had his own.
Whatever assumption you may have from my posts is - again -fine with me.
And not my problem - nor the problem of others.
Whether anybody wants to follow my suggestion regarding a step-up (and seeing moving coil cartridge and corresponding primary .... and secondary if you want ..... of a step-up transformer as a "team") or not is (...you guess it...) fine with me too. |
Lewm, I am very familiar with hybrid cascoded phono-inputs.
Getting gain galore in teh 1st stage is always tempting. I am currently using a full balanced differential all triode phono stage with split passive RIAA. I have experimented with a hybrid cascode input stage too, but I went back to the "conservative" triode input stage. |
Allenwright, Atmasphere, I do agree with Atmasphere (surprise...?). All (low-output) Moving Coils do need "some" dampening. And yes, - in my experience too that extra "air" is going in most (maybe all) cases along with "lack of body" and has a sense of being "artificial" and "somehow ringing".
Saying this I have to mention, taht back in the late 1980ies and early 1990ies I was a vivid frontman accepting nothing but high gain active phono stages and judging all step-up transformers as a waste of time and money.
In the following years however - mostly by using very low source impedance moving coil carts - I learned that there is more than just gain to a happy marriage between a top-flight mc and the matching transformer.
Knowing 3 cartridge designers personally, I do know that they do care about sound and the last jota of possible performance a lot less than I do.
Still the best "loading" and "dampening" for a low-output (= very often low source impedance) moving coil is in my ears and eyes a matching transformer. |
Lewm, just a general guideline I have found very useable and giving very close to perfect results: choose a transformer which primary is about 10x to 12x the source impedance of the moving coil. Go for a step-up ratio not higher than 1:12. The resulting transformers primary will give a very good matching inductance (and resistance....) to the given moving coil.
The basis has to be a SUT which prime design goal and feature is extremely wide frequency response and extremely little derivation from phase.
Try to restrict yourself for the above recommended step-up ratio - its a kind of "royal device" when going for the best matching in moving coils.
If your source impedance is rather high - say 20 to 40 Ohms (some DL-103 clones etc, Koetsu Urushi, Clearaudio etc.) - do lower the step-up ratio to 1:4 or 1:6.
Always go for quality and low step-up ratio in SUTs - NEVER go for high "gain". The majority of the gain must always come from the phono stage itself.
The extra gain from the SUT shouldn't be as much as possible, but as little as possible.
I do use a SUT always as a matching device in the first.
The extra gain is a bonus to me - certainly not the core issue.
Thanks,
D. |
Lewm, as you are one of the true audiophiles who do NOT settle with what the industry put in the package they bought (you have (have had) parts custom upgraded and modified the amplifiers you use), let me suggest you give it a try with your modified Atmasphere MP-1 and a Jensen or Lundahl transformer.
The Jensen 347-AXT can be used with the Urushi and the Lundahl LL-1931 or 1933 can be used with the Ortofon 7500. However none of these is really ideal suited for a VERY low source impedance (and thus inductance....) LOMC while offering a decent (1:8 to 1:12) step-up ratio. If you want to restrict yourself to one SUT first, I would go for any of the two Lundahls mentioned first - they do offer primary options which can accommodate all your top-3 cartridges (vdH Colibri ...).
In SUT - as in cartridges/tonearm combinations - there is no single "BEST" SUT. There are superb matching combinations - and combinations of great individual components (MC and SUT) which do NOT match.
Its again applied skill and knowledge to get the best possible performance.
If you give it a try, I'd really look forward to learn, if you too do hear the "degradations" Atmasphere (..the human person - not the preamp....) hears with his MP-1.
Select the best (read: .... widest frequency response, close to perfect phase = most expensive...) SUT, settle for low step-up ratio, use Lundahls or Jensens recommendations or spread sheets to careful fine-tune the secondary resistor in accordance with the phono input resistance and try to meet the above stated matching rules.
I bet it will proof worth the effort. |
Lewm, please do not get me wrong. A hybrid casode phono input stage is favored by many and for good reason. Technically seen it looks like the best of both worlds and addresses many important technical aspects and solutions in a very smart and tempting manner.
But - as always in life (sic...) there is a price to pay.
That price is NOT high, it is not anything really worth mention, but in the end it is the very tiniest point which keeps the doors of (sonic ...) heaven closed for the demanding listener.
There are sonic trade-offs (as in ALL designs) in ANY hybrid cascode phono input stage. Its open, airy, fast, dynamic and direct sounding. It gives you gain to burn the house and rock the street.
Yes.
But regardless of the tube or FET/J-FET/Bipolar etc. in use - you loose on color, you loose on 3-dimensionality, you loose on micro detail.
The picture is clear, in bright light and alive if a little bit artificial - but less convincing, less like the real thing.
I have favored hybrid cascode (and all-tube cascode...) phono-inputs for a long time and years before they showed up in custom gear in high-end showrooms.
Similar as with my earlier years preference for active phono input stages, I have gone a long way to find out that this is not yet the end of the road.
One should always remember, that the sonic impression is never a lonely one - its the impression we get from a certain set-up and is always depending on the periphery.
You do favor the hybrid cascode phono input now - in the set-up you have put together and listen to with joy.
This is fine and correct.
This may however change (as preferences, individual parts of the set-up or room conditions may change) and you may go back to the original or an input-stage with a different tube one day and may find it suits you better.
Maybe - not necessarily. |
Dear Nandric, plainly spoken: - "we, the people" do prefer the more demanding (complex, problem ridden...) above the simplified because of better performance on the large scale.
Would MMs really be that good, no one would mess with MC - especially not with LOMC.
There are good MMs out there, past and present, but the best can still not compete with the best MCs (...and I was pro-MM all my life and still am..... but they simply are no real match).
God - I hope that this doesn't brings up all the MM-lunatics against me.....
|
Axel, MMs do ease things and they smooth them too - thats why many SS gear do sound "better" when feed by a top class MM.
And sorry, - its not blonde versus brunette (I had many experiences with both....) - its a smart, sophisticated, highly educated and complex girl (some may name it neurotic....) on one hand and a simple minded, good sports country maid (easy to handle..... less demanding) on the other.
Many of my friend say about my wife: "great girl ! But she is very complicated isn't she ?"
I reply: "not at all for me....".
I for one will always go for the more demanding - its the more rewarding too.....
But it needs skill, knowledge and experience to handle..........
The girl and the LOMC.
Message transmitted and received ?
Cheers,
D. |
Lewm, Nandric, my wife saw the thread and my last post and........... smiled.
See - that's why I love LOMCs and a very special blonde I am married to ...... demanding, but rewarding. |
Guess it was a modern day american philosopher who stated that persistence was the only true omnipotence force in human existence (if not in the universe...).
If you had been grown up with german language in the 1960ies and 1979ies - before marketing took over all language in the western world and made us accustomed to 6-word-sentences without any commata - Kant wouldn't be all that frightening.
Funny thing that in England I was always mistaken for being french and in the USA for being british......... now what does it tell us about being german in modern times ? |
Atmasphere - in general I do have respect for your work and the components you have brought to the public. Your designs are well executed and do have the sonic trademark of a designer who listens and has a clear concept.
That is much more than I would say about most other audio designers.
As for the sonic footprint of SUTs.
I would say that EVERY component - passive or active - has a sonic footprint. The skill is to blend the combo into a team which gives us the music with as little signature as possible.
There are SUT out there which do have extremely little signature (footprint). But they are not readily available off the shelf.
We have to dig for them and sometimes have them made to very specific parameters. |
