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New Custom PhonoCartridges

Nat said:
produce a Decca ffss or London that I can afford
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That is probably not my goal. Fixing the short comings of other folks designs doesn't quite excite me as exploring some new spaces does. We learn from these older designs, some things to do, and some things not to do. But probably best to leave the past where it is.

Nat said:
I join those asking for something like the Stanton/ Pickering low impedance cartridges
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ripblade said:
add my vote for a low impedance/low output MI cartridge, something with some of the benefits of an LOMC but with a user replaceable stylus
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Given the improvements in energy of permanent magnets (50MGOe with NdFeB these days) there should be no trouble to keep impedance low and still have high output. Just have to be careful with the soft magnetics circuit design to stay out of saturation.

ripblade said:
What is your experience with cartridge break-in? Is this something that occurs in the suspension, the stylus, or is it purely psychological?
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This is a suspension issue. A properly designed suspension should not have to have break-in time to "bed" itself. If it isn't properly assembled, it might walk itself into a slightly better case where the motional impedances are balanced as they should be. Or perhaps some suspension designs (note I am talking most about tie-wires in almost all MCs and in bunches of MM and MI designs) are too taut initially to account for the stretching of the tie wire with time. I am not a big fan of tie wires for a couple of reasons. One: their general length in a cartridge from connection point at the stylus to the ground point back in the body somewhere necessary leads to a resonance typically around 15-17kHz (the guitar string effect). That resonance can be damped with the application of some schmutz against the wire but the 1800 phase change that accompanies that resonance is there to stay!! Reason 2: Well, more of the magic. Sorry but you can expect that I will never use a tie wire!!
 
I can understand your lack of enthusiasm for trying to fix other people's designs. But it seems to me that the standard diamond on the end of a wagging stick with something else on the other end to generate a signal is also someone else's design, and certainly it has shortcomings, too. In my experience, no cartridge that uses a conventional cantilever has the immediacy and dynamics of the Deccas. Looking at the folded metal piece (Decca calls it an armature, I think) that holds the stylus and transmits its motion to the generating system (which I'm assuming is moving iron), its not obvious to me that it shouldn't have the same issues that cantilevers have, but it sure seems like it doesn't. Other issues, yes, and in spades.
I'm curious what is going on. Is there a relationship between low compliance (and maybe compliance in different axes) and vividness? It does seem that surprisingly old cartridges like the GE and first Shure moving magnet have devotees who speak about them in somewhat similar ways to Deccaphiles.
Any insights?
 
I second the AKG type of cartridge. The 7 and 8 were very,very nice. The trick would be to offer a Moving Iron design that you could buy with different compliance. Say for instant a Stanton 681that sounds the same but one works in a low mass arm,also in a med mass arm, and one in a high mass. That way no matter the arm you have it covered. And do all this for under $200. Yeah, I know I need to wake up now.
 
Pio: I'd guess keeping such a cart in or at least closer to the affordable range would require a direct sales approach, so that the profit wouldn't have to be shared with distributors and dealers and thus the total profit margin wouldn't have to be as high.


Eric, let me have a guess: Second main disadvantage of tie-wired designs might be that there's less of a well-defined pivot point and more of a pivot area. Then again, when I listen to my AT dual/V magnet design MMs with high quality needles, I'm not sure whether that really is that much of a disadvantage - but of course that's always hard to judge, if there's no easy way of making an "everything else equal but x" type of comparison...


Greetings from Munich!

Manfred / lini
 
The other thread had some discussion on a defined rotational pivot point re tie wire vs free pivot and armature "pistoning".
 
The tie wire in AT designs appears to me to be closer to the pivot point than most other designs, so it may have less of an effect in terms of confusing the pivot point.
 
I am pretty sur that you know more about cartridge building than all of us combined. Perhaps it is best to pick a couple of price points and build the best possible cartridges you know how to, and bring those to market. Most of us may have wants/needs, but are not knowledgeable enough to know what is possible when you start putting those itty btty parts together. We can have an opinion on the end product, but how to get there is a whole different story.

Regards
Mister Pig
 
I'm guessing that actually a bunch of wacko suggestions might be very helpful, Despite (or maybe because of) the diminished market for cartridges, the obvious niche/price points are pretty well met. It is going to be hard to compete at the very low end with the cheapest AT or the Red Ed variants, which are decent cartridges for very little money, and a bit above that the AT 95 E and Shure M97 and similar, and then Ortofons and so on filling in the upper ranges of the mass (such as it is) market. I would guess it would be tough selling a new low end cartridge in the face of existing competition -- you'd need a lot of volume, and the market may not be that expandable. And up at the high end, there are a surprising number of alternatives at expensive to berserkly expensive prices, but less and less volume of sales.
So a distinctive product, or one that might sidestep the current organization of the market, might be the route to success.
How about a ceramic/piezo that people without phono preamps could use, but that was of very high quality. I know that Sonotone was getting there (and I believe the MIcroAcoustics was the descendent of their designs, but used a small circuit to lower the output so it could be used through regular phono preamps, something that wouldn't be necessary today). Matched with a U Turn or similar entry table, it would expand the potential market, I would think.
 
Oo, an updated piezo! I like that. I wonder if Kynar (PVDF) film would work.
 
Thank you for all your inputs. For those who suspect that my ramblings point to the pivot and suspension design as critical score high on reading comprehension and insight!! For those interested, I suggest constructing a 6 degree of freedom model for a mechanical mass/compliance system externally driven over a significantly broad frequency range where, unlike loudspeakers which split that range into segments (woofers, mid-range, and tweeters) all of the velocity dependent drive must be linearly handled with a single system. I believe you will find that solving for the power spectral density (PSD) will be nigh onto impossible without a stable and direct correspondence between the center of rotation (should be zero translations) and the center of percussion. The center of percussion is that rotational center which would exist were the system essentially free of any constraints, ie the natural mass balance. If one forces an artificial center of rotation (non-concurrence between rotation and percussion) then off-diagonal elements of the 6 DOF dynamic tensor will not normalize out. The tensor cannot be diagonalized and cross-coupling terms are finite. Tie wires necessarily suffer this fate. Non tie wire designs need to find an adequate solution to the non-translational constraint. Net result: Life Is Hard!!

Regretfully, this text editor does not handle math!! One is looking essentially for the integrated spectral response over the whole frequency range. ie Take the integral of the driven response over the freq range from say 5 Hz to 30kHz for driving function F(w) that is velocity dependent. That means are individual response terms are functions of the recorded velocity signal, x(v), y(v), z(y), Theta(v), Phi (v), and Omega(v). Solution forms for a complex response are often set up easiest (not easily) as the Hamiltonian, H(w). Note that given the velocity dependence of all the response terms, any in-band resonances, even adequately damped in the amplitude domain, will have significant phase rotations ( you must solve for both amplitude and phase).

Thoroughly enjoying the conversation. Frankly, from a market point of view, I wouldn't invest in the tooling necessary to productionize to price assault what little is left of the mass market. Yet, the custom prices some are asking are simply absurd and mostly ego driven. Prices for low volume high end hand constructed should really fall in the $500 to $1500 range. Not cheap, but not $12k either!!!
 
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Would it be possible to produce something unusually good but affordable by utilizing an existent inexpensive body, like that of the Red Ed, but equipping it with a mechanically rigid stylus assembly with the sort of precisely centered moving system you describe?
Without digging into the math, in your view, would something like the AKG suspension, which intuitively seems like it should very tightly locate the pivot point (and whose imaging qualities seem to confirm the intuition) actually locate it more precisely than the usual elastomer block?
 
Nat, I do believe the AKG suspension design to be a good one and does try to address the stability of the pivot point. There is an elastomer block that holds the armature but also an additional tight clearance hole metal plate which tries to stabilize the rotational point. It is a pretty good design and images well as you note.The elastomer is always a part of these designs as it provides the motional damping term for the resonant system. You have some effective moving mass, and some compliance (ie resistance to motion) and just like a cars suspension and shocks, you have to have some damping or the whole thing will be out of control. This brings us into the age old questions of underdamped, overdamped, or critically damped. It is these features in different cartridge designs that determine the sonic characteristics that people identify as "really smooth" (a touch overdamped), "hot", "sparkly", "edgy", "bright" (underdamped), and "balanced", "open", "neutral", "boring" (critically damped). And yes I picked works for those who both like and dislike each of these conditions! Haha

As for ceramic cartridges, I think it would be a while before I played with piezo crystals. I believe I have had my dose of them in the laser business. Kinda want to play with magnetics again.
 
Hello Eric, Tensors and Hamiltonians? Oh dear, reminds me of Bessel functions to model vinyl deformation. I’ll chime in to say that I am very interested -– actually excited! – about the possibility of your returning to the cartridge design world. So I'll offer a few musings.

Experiments re modeling phono pickups has convinced me that achieving flat frequency response is easy. Achieving low mechanical impedance (to allow low VTFs for reasons of record wear and vinyl deformation loss) is also easy. But to achieve both goals concurrently is extremely challenging.

I’ve long been a fan of various top ADC and Shure models (and Paul Weather’s designs before then). The later models in these lines started to demonstrate that low mechanical impedance AND extended flat FR can be achieved concurrently. Unfortunately the goal of low mechanical impedance has been largely abandoned, both for new pickups and replacement styli. Absurdly expensive MCs are the current darlings.

It seems to me that MI/MM technology is more amenable to these goals than is MC. (a.) They are simpler mechanically and probably easier to manufacture. (b.) Having a user-replaceable stylus should be a must. (c.) Tayloring the MI/MM source/load impedance electrical response against the stylus mechanical response is a useful tool to tame the inevitable HF resonance peaks. Low-Z MCs can’t do this, and thus need to heavily mechanically damp the stylus to tame the HF peak – thus leading to today’s overdamped MCs with low compliance, heavier VTF, and the popularity of heavier arms. (d.) A side issue with Low-Z pickups (not having electrical HF rolloff) is that their response above the audio range introduces unwanted ultrasonic input to the associated preamp, leading to potential overload which can affect the audio range signal. (e.) Probably stronger modern magnets can allow coil structures with lower source impedance. (f.) Perhaps also provide greater eddy current damping of the stylus.

So … I see a need for an updated version of the ADC XLM, Astrion, Shure V15V, et al. Probably with a single prescribed VTF (not a range) so that the generator geometry is defined. But are there current compatible arms? Perhaps a matching arm integrated with the cartridge, is the answer. That way the designer has fuller control. (Yep, we’ve been there, done that. Didn’t sell. But still valid.)
 
Charlie S said:
Hello Eric, Tensors and Hamiltonians? Oh dear, reminds me of Bessel functions to model vinyl deformation. I’ll chime in to say that I am very interested -– actually excited! – about the possibility of your returning to the cartridge design world. So I'll offer a few musings.

Experiments re modeling phono pickups has convinced me that achieving flat frequency response is easy. Achieving low mechanical impedance (to allow low VTFs for reasons of record wear and vinyl deformation loss) is also easy. But to achieve both goals concurrently is extremely challenging.

I’ve long been a fan of various top ADC and Shure models (and Paul Weather’s designs before then). The later models in these lines started to demonstrate that low mechanical impedance AND extended flat FR can be achieved concurrently. Unfortunately the goal of low mechanical impedance has been largely abandoned, both for new pickups and replacement styli. Absurdly expensive MCs are the current darlings.

It seems to me that MI/MM technology is more amenable to these goals than is MC. (a.) They are simpler mechanically and probably easier to manufacture. (b.) Having a user-replaceable stylus should be a must. (c.) Tayloring the MI/MM source/load impedance electrical response against the stylus mechanical response is a useful tool to tame the inevitable HF resonance peaks. Low-Z MCs can’t do this, and thus need to heavily mechanically damp the stylus to tame the HF peak – thus leading to today’s overdamped MCs with low compliance, heavier VTF, and the popularity of heavier arms. (d.) A side issue with Low-Z pickups (not having electrical HF rolloff) is that their response above the audio range introduces unwanted ultrasonic input to the associated preamp, leading to potential overload which can affect the audio range signal. (e.) Probably stronger modern magnets can allow coil structures with lower source impedance. (f.) Perhaps also provide greater eddy current damping of the stylus.

So … I see a need for an updated version of the ADC XLM, Astrion, Shure V15V, et al. Probably with a single prescribed VTF (not a range) so that the generator geometry is defined. But are there current compatible arms? Perhaps a matching arm integrated with the cartridge, is the answer. That way the designer has fuller control. (Yep, we’ve been there, done that. Didn’t sell. But still valid.)
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Thanks for your inputs, Charlie. Very much appreciated. I am firmly in the high compliance, low VTF (as long as tracking is under control) school of thought. And I do agree on replaceable styli. You are correct about the complexity of construction differences between MC and MM/MI designs although I have never thought that it had to be so. What I mostly believe, consistent with a number of your comments concerning HF response and resonances, is that tie wires are evil. I will also comment that I don't believe that induced eddy currents in these magnetic circuits can provide damping of sufficient scale to tame mechanical resonances. I can visualize a variable reluctance design where the minimum magnetic circuit reluctance provides a restoring force similar to poling in a multi-pole motor but again, the scale differences in driven forces and reluctance forces would be tough to normalize.

And I sincerely appreciate your enthusiasm for a new (well, re-cycled) player in the present market. I am proceeding with some of the background work necessary to move this forward and we'll see if it can be made sensible to see this all the way through. It isn't just a technical question but a decent business case has to be made as well. The resurgence of interest in analog audio provides the opportunity. Just have to do enough market analysis to see if it is sustainable and not just a passing fancy. Asking those participating here if they think analog is the way to go is a bit too much like preaching to the choir. The question has to be posed to the larger audience to have the answer be valid.
 
OLDADC, it warms my heart to hear that you're interested in re-kindling some of that old ADC magic. I agree that with the resurgence of vinyl there may indeed be a niche for a good (I presume Induced magnet?) design. I too prefer a non-tie wire design and may be crazy but swear the tie wire adds a coloration that detracts from the sound. With your association as Engineer and designer with the legendary ADC name you should capitalize on it and maybe one of the crowdfunding web sites might be a direction you might want to consider. I am very enthusiastic though being retired I probably wouldn't be able to afford one of your cartridges.

Dave/ChairSpud
 
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