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. |
A slight bit closer to topic... Dertonearm, your description of the difference between hybrid and all-tube cascode is very similar to how I would have described it.
There are a number of manufacturers that use semiconductors right at the input of their otherwise 'all tube' preamps. I feel they loose that last bit of natural detail, so I go for the tubes, although there is a little more noise. Despite that, I win back the detail that the semiconductors seem to loose.
In the last 2 years, we added a new CCS circuit that is able reject noise from the power supply while maintaining precise current for the differential cascode gain stage. This reduced noise, increased bandwidth, increased gain and reduced distortion all at once. The RIAA spec works out to 0.15mV; so with good tubes in the unit I've found no need for transformers.
We have offered the Jensen SUT as an option for years, but with the introduction of this circuit no-one has installed that option. We do run into noise issues on occasion- we have found that the vast majority of NOS tubes (that occasionally get installed by end users) are simply not quiet enough to do the job. However there is an ample supply of new tubes.
I have yet to find a transformer of any variety or application that does not have a sonic footprint, be it SUT, line, interstage or output. There are of course advantages- gain and isolation being two, but if a simple circuit can be devised to bypass the need for a transformer, then greater transparency is the immediate reward.
From a previous post I am asked to assume that you have one of the most neutral systems in the world; however I exhort you to consider that if you have heard a particular piece by a particular manufacturer, please keep in mind that we manufacturers are often doing our best to make improvements over the years and are often quite successful at that. So you would be doing any manufacturer and yourself a disfavor by 'assuming' that since you heard a unit five or ten years ago, that you thus 'know' what that product sounds like today. |
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 ? |
Dear Lewm, Colling them 'Kantian' is an diplomatic way to
say that they are stubborn (the Germans). BTW I was not able to reach page 12 of 'The critic of the pure reason' and I was trying for an month or so. Beacause of the lenght
of his sentences as well as the used vocabulary I lost the Ariadne thread halfway of each of those sentences. I assume
that my phylosophy teacher was confronted with similar problems because I pass somehow for Kant.
Regards, |
Nandric, Here you invoke the categorical imperative, no doubt. |
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. |
Dertonearm, There may actually be women who read this thread, so I would be careful. For example, your wife may have access to the internet. Nevertheless, this reminds me of the belt-drive/direct- or idler-drive controversy as well. But seriously, I found and am finding with the hybrid cascode that the sound was very affected by the choice of the tube in the top part of the cascode. Once I made that choice, the sound is further greatly affected by the value of the plate resistor (which of course has a critical effect on gain) and the amount of current through the circuit. (Primarily, I found that lower value plate Rs sounded better, less sterile, up to a point where the plate R = about 10X the Rp of the tube itself.) Also, how one sets the voltage at the grid of the top tube makes a noticeable difference. All of these elements greatly alter the presentation of the qualities you discuss, not to mention the similar choices that needed to be made with respect to the phono output stage. That's what makes this an endlessly interesting and sometimes frustrating hobby. (PS, I would never recommend doing what I have done to a brand new Atma MP1, which is a great unit bone stock. My own unit was VERY used when I bought it and needed a lot of refurbishing to begin with, so I let my imagination run a bit.) |
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. |
Dear Dertonarm. I dont belive that Kantians are suitable for 'corps diplomatique' but you should use some other expression,say,'MM lovers' to 'baypass' the problems that you already anticipated.
Regards, |
You guys are getting interesting and funny too. Well, thank you for sharing some of this empowerment.
Messing with MCs problems, as messing with any on-going problem has a 'pay-off', otherwise no-one would bother. As long as it is fun and entertaining and not frustrating, it's jolly good entertainment.
As to the MM side of things, it also should better be fun and not any of this competitive BS like: like my 'spanner' is longer than yours...' etc.
I think a lot of phono-pres are ultimately not up to the task of really GOOD! and COMPLETE! low-signal amplification.
Just pumping up the gain without loosing some of the incredibly delicate detailed LOMC signal output is a VERY demanding task.
In this case an SUT will make a difference, or an MM in its own unique way also.
I find in my (all) SS system, MM carts generally have more 'information density' in the mid-range, than MCs provide through my phono-modules. There is something very natural and touching in how MMs handle that area. The interesting thing for me is, that *ANY* resistive MC loading makes for some of this 'coldness', experienced with CD reproduction -- and it maybe simply a more 'favourable' impedance match when using a step-up that improves on this.
With MMs the trade-of mostly (or always?) is some degree of lower-treble to upper-treble lack of definition. The sort of thing that slightly lesser recordings often might show.
With excellent recordings this 'lack' is hardly noticeable, unless in an A/B shoot-out, which comes with its own set of problems.
So I say, enjoy both! as both have there characteristic strength and weaknesses (a bit like blonds and brunettes :-)
Cheers,
Axel |
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.....
|
Dear Dertonarm, The comment of an cseptic (?) by the first evidence that sigaret-smoking causes cancer was:'everybody
will swich to pipe'.
Now I am not sure if LOMC causes cancer but,looking at your
exchange with Lewm,I am sure that LOMC already causes considarable headache.Shall we all switch to MM carts and follow Raul? I can't remember any comment from you about the MM carts (Also wenn Sie so freundlich sein wollen?).
Then we have some kind of an paradox. The most of us prefer
the LOMC. Do we prefer difficult problems obove the simple?
I.e. there are no (intellectual) rewards for solving simple
problems.
Regards, |
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. |
Dertonearm, Re your sentiments on the hybrid cascode, we have another subject where you and Atmasphere are in agreement. Ralph also recommended that I stick with tubes in both positions. I have no axe to grind; I know for a fact that the topology can sound very good either way. The MAT02 is pretty special in this application, so conclusions drawn using other solid state devices on the bottom of the cascode may not be so applicable. But I am a neophyte in these matters and not qualified to argue either way, except based on my own particular listening experience with this set-up. If I get the energy, I could go back to an all-ECC99 cascode and use a low gain SUT to make up the difference. |
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. |
Thanks, Axel. I am comforted to know that you like that set-up, because I never could quite understand how a 13-ohm load could be superior to any higher value resistance, using your cartridge. 47 ohms is more in the ballpark of what I would guess would work well.
Dertonearm, thanks for the tip. Unfortunately or fortunately, I modified the phono input stage of my MP1 to use an MAT02 bipolar transistor as the bottom half of a cascode, where the top half of the cascode is now an ECC99, in dual-differential configuration. This, in conjunction with the output stage gain section, gives oodles of gain, even for the Orto MC7500. (The MAT02 has a Gm of 400!) And I am very pleased with the sound quality. I guess I could use a VERY low step-up ratio SUT, just to test your hypothesis. And there are tricks I could use to reduce the gain at the input, as well, without changing the topology. (I have to do this when I use the Colibri, which puts out 1.0mV.) |
Lewm,
+++ ... Axel, are you saying that you now like a 47-ohm resistor on the primary side of your SUT? I presume you also have a 47K-ohm resistor on the secondary side. Is this correct? +++
No! please see below.
A 30dB SUT (1:31.6 ratio) has a "natural impedance" of 47 ohm when going into a 47k secondary input impedance (the phono-pre).
Since the primary impedance = secondary input imp./ ratio ^2 = 47k/31.6*31.6 = ~ 47 ohm primary impedance.
So what I now like is the 47 ohm primary *impedance* of the SUT without ANY resistive loading (other then the negligible 1.1 ohm of the primary coil winding itself...)
I hope this should clarify the matter.
Greetings, |
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, FWIW in working with the Jensens we notice more degradation when they are set for the higher stepup ratios and almost none at the lowest stepup. (Jensens have multiple windings that allow a variety of combinations for different stepup ratios.) The lowest possible is usually sufficient for most preamps (1:4). While I don't agree with Dertonearm (the effects of the transformer degradation are easily heard, at least on our gear), his recommendations otherwise corroborate what we have found. |
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. |
Guys, All of this stuff is anecdotal and subjective. Dertonearm wrote that the inductance of an MC cartridge is a major factor contributing to his finding that SUTs are inherently the superior method for the first stage of amplification of the output of an LOMC. He inferred that a simple resistive load in front of a high gain phono stage cannot properly correct for the inductive property of an LOMC. I am trying to find out how one uses that information (the cartridge's inductance as quoted by its maker) in selecting a SUT.
In another vein, Axel, are you saying that you now like a 47-ohm resistor on the primary side of your SUT? I presume you also have a 47K-ohm resistor on the secondary side. Is this correct? Thanks. |
I had not used a SUT since the early 80s but decided to try one. I ended up getting a Bob's Devices Cinemag one. I was surprised at how good it was at a moderate price[$395]. I use a Blue Circle 707 which has enough gain without it. With it I can hear detail that was not present before and can detect no downside to its use. I only read the review of it on Ten Audio after I bought it but it is very close to what I hear also. I don't really care about the technical details, just the final sound. I have not had extensive experience with it yet but so far I would agree with Axelwahl. |
Lewm,
you are quite right when you state:
...this suggests that the inductance has a negligible effect on the cartridge's internal impedance at low frequencies and only a modest effect at the top-most frequencies,...
Knowing this will tell, that in my example the 20Hz - 20kHz impedance will not vary too much in terms of the 4 ohm quoted DC Resistance.
Now, what parameter(s) make for a good SUT match? --- the 1k$ question *without* listening!
Example:
With a ~'faulty VTA' cart of same make and build the SUT mentioned worked best with a 13 ohm loading resistor in primary, which produced a impedance match of 2.5 times the cart's quoted DCR.
With a new replacement cart, 47 ohm (i.e. no resistive loading) sounds better.
Therefore the next impedance match rule of (SUT): primary input impedance to be >10x cart output impedance, seems a better match. The >10* is a voltage favouring match, the 1:2.5 is a current favouring match for power transfer.
Therefore you can still figure good matching by use of resistive loading.
The first point: to have *NO* phono-pre over-load and the second point is impedance matching by listening test.
In the case of 20uH it is OK to neglect it in your CALCULATION! B U T it still makes for the better LO-MC cart match, using an SUT rather then a resistor.
It can be heard: the proof is in the eating of the pudding.
My own theory: practically ALL high gain phono-pres of AFFORDABLE designs loose micro information when amplifying ~ >0.3mV cart out puts... YMMV
Greetings, |
Axel, Can you or Dertonearm tell me how the quoted 20 uH inductance of the Windfield was taken into account in your choice of SUTs? You make no mention of the way in which you may have used that information, and Dertonearm did not really quite get there either, in responding to my earlier question. By my calculation, an inductance of 20uH will result in an impedance of 2.5 mohms at 20 Hz and 2.5 ohms at 20,000 Hz. In an MC cartridge, this suggests that the inductance has a negligible effect on the cartridge's internal impedance at low frequencies and only a modest effect at the top-most frequencies, not enough to affect dramatically the choice of an ideal load R, if no SUT was used, but obviously the impedance will increase with frequency ad infinitum. |
It is a pity, that common Phono knowledge gets buried. Of course the user will find THE exception (SUT or high gain Phono) but may I add something important:
I listened to transformers from horrible-excellent, but honestly, horrible was majority. Colored, wrong in reproduction, channel separation and so on... I did that for 3 years with various units (EAR, Kondo, endless cheaper units) and at the end of the road I use now a top unit with 1.rate studio specs. No Hype, no miracles, just measured - and compared - datas.
And before I did that, I wasn't really mad for them.
Most manufacturers have no idea about the sense behind, they offer it - more or less - to make some money, top trannies are ALWAYS expensive, there is no way out and we know from former discussions, "expensive" is the most hated word in High End
(High End but lowest price, funny eh?)
But honestly, before some readers will say: "Great" after reading that and think, that is the - cheap - solution for everything: no, it's not.
It is just one more piece in the analog puzzle. |
Hi,
looks like we are back with the SUT business...
Let ME state categorically that the Dertonarm IS RIGHT with regards to a LOMC (>=0.3mV) producing more 'natural' sound with a correctly matched SUT.
Even with a pretty modern design cart like an Ortofon Windfeld that can pretty much work OK with loads from 500 - 47k ohm it sound *absolutely* better more natural with SUT.
In this case example: 4 ohm source impedance, ~ 20uH source inductance, and 0.3mV output.
Matched to an SUT of 30dB (1:31.6) i.e. 47ohm primary input impedance going into 47k phono-pre.
Primary DCR of SUT = 1.1 ohm)
Phono-pre is all SS, and in fact MORE quite! without SUT when set to 78dB. Using the cart with SUT gives more natural 'ambience' and depth information without perceivable loss of detail what so ever.
In comparison 1k resistive load gets to 'hot' in very dynamic passages, and already too 'sat-on' with ~500 ohm. Loading with 100 ohm sounds completely dead, or as Dertonarm pointed out by using the simile of far ยtoo much feedback likeย sounding.
Now go figure...
Greetings,
Axel |
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. |
Allen, a peak past 'audibility' will have effects not unlike a tube without grid stoppers, exhibiting oscillation; IOW it can behave as if there is excessive ultrasonic energy. This can cause some preamps (not all) to exhibit excessive ticks and pops (in addition to brightness), due to the various instabilities introduced. The effect on the cartridge is easily measured, and without loading often there is more 'air' but when you examine it on the scope you will find that the 'air' is mostly just ringing (distortion).
This is why critical damping is such a nice value to achieve- you get out the the transducer just the signal, without additional 'commentary'. I suspect many cartridge distributors don't listen to any cartridge for very long so it might be that they don't bother, but they are simply missing bet, that's all. |
I know personally five top line cartridge makers, and when quizzed on this question, they all confided to me that they themselves, use 47k. loading.
When asked why they then recommend much lower values in their instructions, they all said it was because of the "fixed opinion" of most reviewers and audiophiles that such low output MCs need a low value resistive load, and that they didn't want to buck the trend!
I have found every cartridge I have owned, or have ever used, sounds more alive and vibrant at 47k - except for one - the unusual IKEDA, which did sound better at around 100 ohms.
IME, loading a cartridge is not the correct path to handle unwanted tonal qualities, changing the connecting cable can do more with less losses. And my own theory on why loading can change the characturistics of a cart is that they all have a HF peak, and loading can flatten this out. But this peak is normally well above audibility, so what's the problem? I say it's overloading a non optimum phono section, and that's the area you should be looking at to really hear what your cartridge can do!.
Regards, Allen (Vacuum State) |
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. |
Dertonarm, I'm not familiar with any MC unit that actually loads correctly at 10 ohms! I imagine that the results might sound like the application of excessive negative feedback, but it is *not* in fact feedback.
Even though the Jensen transformers are some of the best (we offer then as an option), I've yet to hear a situation where they actually sound *better* in all regards. Usually, they help a lot with noise, but the best I've heard over the years, time and time again, they rob the signal of detail and 'air', as well as bass impact.
The exception to that is if the MC signal by itself is too low for the phono stage, then the transformer is a benefit; actually *adding* impact, reducing noise (and thus revealing detail). So from your posts above, is it simply that the phono section you are using falls into that category? |
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........ |
Dertonarm, the use of the word 'feedback' in your posts above either has a new meaning for the term or else the term is misapplied (language issue). My theory is the latter right now. There is an ideal loading for any inductive audio device wherein the device does not exhibit either ringing/overshoot (under-damped) or excessive rounding (overdamped). This can be accomplished with or without a stepup transformer. Loading can be used as a sort of tone control but is ill-advised, but sometimes very difficult to set up otherwise if the right equipment is not available (which is a 'scope and a squarewave generator). With the test equipment, the inductive device (cartridge) can be 'rung' by the square wave and the resulting waveform displayed on the scope. Without loading ringing will be observed. A load in parallel with the output of the device will cause the ringing to decrease- there will be some point where the ringing will cease altogether. If loaded excessively, the corners of the square wave will be rounded. The debate about where critical damping lies centers around whether or not any overshoot is allowed (I tend to go for a slight amount). At this point the loading value will be only slightly higher- often the difference of only a few ohms. A transformer can complicate the matter as the transformer can ring also. In addition, the load on the secondary will be 'transformed' by the transformer to a load on the cartridge, so if you are loading the secondary this must be taken into account. Jensen transformers has published a chart of how this is done with their transformers (they make some excellent SUTs BTW). http://www.jensen-transformers.com/design/MC_Table.zip |
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. |
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. |
Dertonarm, Can you please amplify on your statement? For example, what would be the effect of a mismatch between the inductance of the phono input in a SUT-less connection and the inductance of the cartridge itself? I am having trouble visualizing this. Also, how would one calculate the inductance at the input of a phono stage? In almost all cases, the cartridge is "looking at" a resistor that constitutes the load. Most resistors have reactance (i.e., inductance and capacitance) at extreme frequencies but not significant at audio frequencies. If inductance is so critical for a direct connection between cartridge and phono, then perhaps the choice of resistor type is also critical, e.g., wirewounds are the most inductive types that I know of. Further, would you ever advocate adding a very low value inductor in series with the load resistor, in order to match the input to the cartridge? (That brings up another question, are you thinking about inductance in series with the connection or in parallel, where the load resistor sits?) Most of us who don't use a SUT are not used to thinking about inductance with respect to cartridge/preamp matching. Thanks. |
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......... |
That reminds me, when someone listens to his System with a dull cable and asks for something better, that there will be an advice from a friendly "supporter":
"Buddy, turn the volume up"
and the answer will be:
"Great idea. Thank you"
Having no idea isn't the solution |
Dear W8aaz: You are spot-on on the subject, especialy when you go from 100 Ohms to 47K!
regards and enjoy the music,
Raul. |
beware that the audio level will probably change going from a low load to very high, so sometimes louder sounds better, be sure to compensate the volume setting to be sure. |
I have found that the lower the setting, the thinner and lifeless the sound gets. Too high of a load and the sound is bright and brittle with too much edge detail. It will not hurt anything to try different settings. Let your ears tell you what is right in your system. |
Thanks for your reply.
I am using a Modwright phono stage, I set the switches on it to 100 ohms first with the Denon S1, and it sounds good but a bit on the thin side with much less bass than when I set the switches to 47K ohms. At that setting the system sounds louder and the bass is deep, and the highs sounds good also. I did this test with the volume at the same setting. I will do some more experiment with the phono stage set to different load setting to hear the result. |
You have to try it. There is no Standard (unfortunately). The result will be different from Manufacturer to Manufacturer. Phonstage A with 100ohm will not sound identical to Phonostage B with 100ohm...There are a few MC Phonostages out there which have excellent results- Speed, airy high frequency Aera, headroom, deep soundstage, holographic Body - with 47kΩ (Stan Klyne, CTC, Vendetta...) but most will sound thin and lifeless at that Setting. Depends on Design. |
I'll add my 2 draxmas into this discussion. Its mostly personal taste. I experimented with the settings in my ASR basis exclusive and found that with each change there was a very subtle but obvious difference. In this case, there are dip switches that allow for immediate change while listening to the music. BTW, I use a ZYX airy 3 with .24mv output. I dont remember what setting I left the dip switch on, but it was mainly based on sound rather than any technical info. Cheers |
Dear Almandog: I own that cartridge an works beautiful at 100 ohms. Btw,, according with the phono stage ( you own ) manufacturer specs that phono stage works well with LOMC cartridges with an output level as low 0.2mv, the DL-S1 has a lower output than that figure so chances are that you can't achieve the best performance for that cartridge.
Regards and enjoy the music,
Raul. |
It won't hurt to try it, this is a highly debated topic. Could they have tested it using one of Denon's step up transformers? These would work into 47K without question. I have three different Denon MCs and use them this way. They make a series of transformers designed for their moving coils , without them I always thought the loading would be in the 100 ohm range. |
