[neobop]

First a little background - A few members here, participated in a group review of the DL-S1 on another forum. That thread is probably no longer there but it was very interesting, at least for the participants. While most of the reviewers has great results and thought it to be a wonderful cart, two of us had mixed feelings. I had a lot of trouble nailing down the the right load. I started out around 300 ohms, varied it up and down somewhat but couldn't get entirely satisfactory performance. On acoustic music it sounded as if there was a distortion that emphasised the overtones. It gave everything a goosed up sound that became fatiguing. I wasn't able to resolve that and finally mailed it to John TCG, for the next evaluation.

The DL-S1 is rather unusual in that it has 0.15mV output and 30 ohms impedance. It also tracks light, something like 1.3g, if I remember correctly. It has an aluminum cantilever and a special elliptical stylus. On an Audiogon thread there was a discussion about cantilevers and the DL-S1 was mentioned. Johnathan Carr (designer of Lyra carts) came on and mentioned that some aluminum cantilevered carts have extended response, and all of them do not resonate within the audible band. In response to my mentioning these loading problems, his response:

>The current DL-304 and DL-S1 are somewhat unusual.

>They also have very low output and 30 or 40 ohm impedance!

That is because the coil former is non-permeable, and therefore, rather inefficient in terms of generating electrical output from physical motion. But in return for that inefficiency, they avoid the distortions that all permeable cores inflict. All MMs and MIs have this distortion. So do most MCs that offer relatively high output voltage in comparison to their impedance. So do Raul's beloved step-up transformers (^o^). But non-permeable core MC cartridges like the DL-S1, FR-7, JVC L-1000, Benz-Micro Ruby et al, don't.

>Results seem very system dependant.

A cartridge like the DL-S1 prefers to have as few electrical contacts between itself and the phono stage input as possible, and a v-e-r-y good phono stage. In this sense, their requirements are no different from any other low-output MC. A little bit more extreme in degree, that is all.

That's interesting. I didn't know why those Denons had such high impedance and minuscule output. Some more considerations:

A "forgiving" phono stage is not what I would recommend for the DL-S1, nor for that matter, any other LOMC. The obviously desirable properties for a good MC phono stage are high gain, low noise, high immunity to RF, high overload margins (which implies high maximum output levels), and minimal deviation from the RIAA curve. Low capacity within the input stage benefits resolution and sound quality, but this partly conflicts with the requirement for low noise, so the phono stage designer must keep a sense of balance and trade offs.

One more critical requirement IMO is low capacitance between cartridge and phono stage, with the tonearm cable being the biggest contributor. The signal coils of the cartridge possess inductance, and this will react with any capacitance between the cartridge and phono stage to create a big resonant peak at ultrasonic frequencies (frequently in the RF range). This peak is much higher in frequency than any human can hear, but it can upset the circuitry of a phono stage that hasn't been designed with adequate consideration to RF or high-frequency overloading. This is eminently capable of of causing IMD at a much lower frequency, and this you can hear. This kind of IMD is quite obnoxious to the ear, since it is non-harmonically related to the LP signal, and therefore can sound outright dissonant.

Reducing the input impedance at the phono stage helps squash the RF resonant peak and thereby can reduce the phono stage's IMD that the ear finds so grating, but in return such heavy loading throttles the dynamics, transients and low-level resolution of the cartridge. Far more advantageous, IMO, to use a phono stage that doesn't need for the cartridge to be throttled down to make it listenable.

A phono stage designed according to this philosophy should have the side-effect of making records sound more quiet, because ticks and pops and tracking distortions will simply be treated as normal signals, and will not trigger circuit misbehavior.

FWIW, I have never had the need to load down any cartridge to under 100 ohms, for any phono stage that I have designed, and believe that I could afford considerably higher loading than 100 ohms with the DL-S1.

The loading situation with LOMCs is very different from MMs and MIs, where capacitance is needed to properly tailor the frequency response.

I note that some designers of MC cartridges and phono stages use quite massive amounts of capacitance to roll-off any ultrasonic peak from the coil inductance-cable capacitance resonant peak, but personally I have found this approach to take away more than it gives.

So there you have it. The loading down with < 100 ohms came from somebody on Asylum who loads it at 30 ohms. You lose half the output doing that. I didn't go below 100. My AHT phono has almost no capacitance. If I knew the situation I could have gotten a couple of caps and tried that. That overtone thing I heard was probably IMD. I guess system dependant was right after all. Now I think I know why.
neo

[neobop]

I thought that some others (beside myself) might find this bit about non-permeable cores in some MCs, interesting. Here is a further description in response to David's questions:

When a piece of permeable material is placed in an external, alternating magnetic field, it takes on varying degrees of magnetism and alternates polarity (to follow the field), but that magnetization follows a lagging, hysteresis curve (which is therefore non-linear). Also, the curve that the permeable piece follows for increasing magnetism and the curve for decreasing magnetism are not the same, and are offset (remanence).

Even when testing inductors, which don't move and are therefore simpler in their behavior than the moving cores, magnets or iron in cartridges, if you have a sensitive measurement setup, you should be able to measure intermodulation distortion with a permeable-core coil and not so (or much less so) with an air-core coil, and probably a certain degree of hysteresis losses as well.

For non-permeable materials, the ratio of magnetic field strength to flux density (in a cartridge this means the material's ability to attract magnetic flux lines to itself, and is therefore tied to conversion efficiency and output) is constant and linear. With permeable materials, the ratio of magnetic field strength to flux density, varies with flux density.

When the cores, magnets or irons move, as in a cartridge, the closer a piece of permeable material approaches a magnet, the more strongly it is attracted (but again following a non-linear curve), and therefore requires comparatively more energy for the piece of permeable material to change direction. With this, we start to see that there can be interactions between the electromagnetic and the physical behaviors of the cartridge.

As an aside, I devised "The New Angle" technology as used in our Delos and Kleos cartridge models largely because I wanted to break or at least significantly reduce these undesirable interactions.

The Barkhausen effect tells us that a permeable object takes on greater or lesser degrees of magnetism when subjected to an external magnetic field, but does so in distinct steps rather than smoothly. It also tells us that the difference in energy between steps is subsequently released as noise bursts.

And so on.

>When I measure a cartridges response, what patterns could I look for that would identify or be associated with permeability?

All MMs and MIs use moving permeable materials. Most MCs do as well.

>How do I identify a non-permeable core cartridge?

If you see an MC that shows very low signal output in comparison to the internal impedance, chances are that it uses an air-core coil, although it is possible that the magnets are simply old and weak.. Again, you could search for Benz-Micro Ruby and others, Denon DL-1000A, DL-S1 and others, Fidelity Research FR-7 and others, Highphonic MC-D15 and others, Jan Allearts MC2 (not MC1), JVC L-1000 and others, Nagaoka / Jeweltone JT-RII and JT-RIII, Satin M-21P and others, Ortofon MC-3000 and others, Sony Soundtec XL88, XL-MC9 and others, Yamaha MC-1000 and others,.

neo

[DaveyW]

Hi Neo,
I was actually typing a response when you came in with your second installment - some very intersting points there.

As you say there was some division amongst the various users which left that study rather frustratingly, a little open ended. The capacitive loading angle offers some extra light which possibly helps close it out.

So just to compare  - I run the DL-S1 thru a Pro-ject Phonobox SE II with 120pf capacitance, the Linn's cable is reputed to be in the region of 140pf.
Hits the spot for me at 100-200ohms with the fixed 60dB of gain, at sub 50 ohms the output becomes an issue.
I have never grown tired of this cart and love the extra body it delivers over (to varying degrees) the other MC's (low and high output) I've auditioned.
Ten months now on the Ittok and still no urges to look elsewhere 

Thanks for the update,
Dave

[neobop]

Hi Davey,
Yes, I remember at the time it was frustrating for me. It isn't a quick and easy task to change resistance on my AHT. I have to unplug it and physically change the resistors in little sockets. Then the DC offset has to be reset, which takes a little time. I was doing this after work and had too little listening time. I heard the potential but couldn't get rid of that harmonic distortion. I have 50pF on the input and no other caps (except power supply) anywhere else on the board. If I get to try a cart like that again, maybe a couple of caps across the inputs would fix that.
neo

[TheChairGuy]

It's been a while now, so I cannot remember which table I paired it with....either the VPI Classic or JVC QL-Y66F. 

For neither do I know the interconnect capacitance levels, either.

My pre-amp is a Pioneer Elite A9 receiver acting as a full functioned preamp only.  The MC section is simply not that good - a few low output devices have sounded barely fair on them.  Despite this, the DL-S1 sounded the best of all and was entirely enjoyable.

The MM stage is really very enjoyable, so I tried an outboard, battery powered step-up and I didn't find it offered up an improvement over the built in MC section. 

All in all, just a great cartridge, tho.  I still find the uber-modded Grado1 to be more enjoyable (and one of these days I'll get the right loading for the Pickering XLZ-7500 and it might end up the best of all)...but, I could understand where one might love the experience with the Denon more. 

I remember neobop mentioning issues he had with it (and vastly more experience than me with MC's) and I couldn't make sense of it myself, but chalked it up to greater experience or something else.  So, above, we may now see the reasons for the divergence of opinions on the cartridge.

John

[neobop]

I suspected that the specs had something to do with the odd results. I had no idea what it was. It's only those two Denons that are built that way. I saw a review of the 301/II and apparently it's the same as the old 103d. That was called the high compliance 103, but it had the special elliptical tip.

I don't know if it was mentioned on this forum, but most current Denon carts can be bought at a heavily discounted price at Comet Supply. You might have to wait for months, depending on their stock. People have gotten them though. I think it's safe to say that they're grey market. That means your warranty is only as good as Comet is willing to back them. This isn't an endorsement for Comet. I haven't dealt with them.

http://www.cometsupply.com/advanced_search_result.html?keywords=denon&x=3&y=4

Davey has some samples on his site.
http://daveyw.edsstuff.org/

neo

[DaveyW]

How about some pics to add a bit of extra context?

DENON DL-304



100X



DENON DL-S1



100X



200x



And again at 200x - modified lighting





Both are very nice carts 

[dlaloum]

Hmmm another area of cartridges to explore...

magnetic core permeability....

I do wonder whether that aspect is possible in a MM/MI design?

The XLZ7500 seems to have the sort of specs that might.... (does anyone have copies of original marketing material for these?)

For the time being I will wait for my Karat 23RS to be delivered and pray that it is in fact a "minty" as advertised.....

The Dynavector Karat series fascinate me due to the very short cantilever made of extremely rigid material (theoretically should eliminate the mid-high droop common to all longer cantilevers I have tried so far...)

Now I find myself interested by the non-permeable core idea.... and there is no information on this topic from Dynavector (so I assume that they use a permeable core...) - on the other hand 0.2mV or thereabouts (hard to find specs for the 23RS) from 30ohm.... perhaps it is using a non permeable core after all?

Maybe a Denon DL-S1 or 304 will find its way into the stable at some point...


bye for now

David

[DaveyW]

Guys - Do we think there are any relevant comparisons that can be drawn between this and the Shure V15 (III, IV & V) Laminated Magnetic Core approach?

[dlaloum]

I have been wondering that myself.... also the Technics TOTL cartridges also used laminated cores....

But I have never been clear as to what the impact of that lamination is....

[neobop]

No moving magnet or moving iron can be non-permeable. Even though designs differ, they rely on the magnetism for the high output voltage. Comparing the output to impedance in the Dynavector, you'd think it would be a good bet that it's non-permeable. I don't think it is. If you take a look at the other (current) models, some also have low output compared to impedance, but are permeable.

**Another unique feature to Dynavector is their softened magnetism, ferrous metal strips arranged to alter the magnetic field. These two features combine to eliminate the distortion caused by excess magnetic flux produced by the high energy magnets used in modern cartridges.**

The 17D3 has similar output/resistance relationship as the 23RS, but has a similar description of magnetic properties -

 http://www.needledoctor.com/Dynavector-17D3-Phono-Cartridge?sc=2&category=370

I think you'll have to look at the list (above) for vintage models that are non-permeable. For me, this is a two edged sword. In order to use a non-permeable cart, I would have to add capacitance to squelch the ultrasonic havoc. I'm not even sure it would be effective. Apparently, the inductance of the cart combines with the capacitance to create this effect. So, if I put some caps across the inputs, who knows if it would work? I guess I could use it with a different phono stage. Obviously it sounds great with a Phonobox SE-II. When this bike (group review) was going on, I wrote that this cart was the one that got away. Now I think I know why.
neo