Not sure I follow you there..
It would probably mean designing or modifying a tube phono design for a little less overall gain and a bit more headroom in the first stage or dispensing with the transformer and designing for a little more gain. Not too hard actually.A dedicated mono phono pre might not be a bad idea imo. A single channel of my muscovite mini for example with a well filtered or regulated 300V supply would do quite nicely at modest cost.. (Cheap Russian tubes)
For those you out there like me who own one or more TD-124 turntables I can confirm that under certain circumstances that the SPU and the cast iron platter are not a combination made in heaven; specifically if you are not running the top platter and mat.
I recently installed a cast iron platter on my older TD-124 which was pieced back together from bits and pieces acquired over a long time. I've run with a glass top platter for a while and tonight decided to remove it and put the gem dandy mat right on top of the platter. I reduced the tracking force on the clone 3012 by a gram and put a record on. Unfortunately the magnetic attraction pulled the cartridge to within a mm of the record surface and it mistracked. Experiment ended with no damage done.
Note that the glass platter places the mat at approximately the same height as the gummis and upper platter.
Just something to bear in mind with the SPU and cast iron platters. I've otherwise not had a problems over a year or more and have found these platters to be a worthwhile upgrade on the 124.
I recently installed a cast iron platter on my older TD-124 which was pieced back together from bits and pieces acquired over a long time. I've run with a glass top platter for a while and tonight decided to remove it and put the gem dandy mat right on top of the platter. I reduced the tracking force on the clone 3012 by a gram and put a record on. Unfortunately the magnetic attraction pulled the cartridge to within a mm of the record surface and it mistracked. Experiment ended with no damage done.
Note that the glass platter places the mat at approximately the same height as the gummis and upper platter.
Just something to bear in mind with the SPU and cast iron platters. I've otherwise not had a problems over a year or more and have found these platters to be a worthwhile upgrade on the 124.
On one of my TD124's. 13943. I have used the 5mm thick Boston Audio Mat 2 directly over the pads of the iron platter. Just before doing this I was able to determine that the Standard aluminum outer platter with mat have the same cross sectional thickness as does the BA Mat2. So in that exercise no vta adjustments necessary. Same amount of magnetic pull from the iron platter below.
Fwiw, the BA Mat 2 works well and does provide some sonic benefits in direct comparison to the aluminum outer platter with rubber mat.
At that time I was using a Wood bodied Denon Dl-103R with SS ruby/FL diamond tip. I had also been able to determine that at 5mm above the pads of the iron platter, the Denon exerts .5 grams of pull toward the iron.
See link to see how I determined this:
mag attract
I do think that the primary means of mitigation is to provide greater distance between the iron below and the magnet above. It is an easy and livable adjustment to make. At this point I've no experience with SPU on a TD124. I expect the SPU magnet to have more energy than the Dl-103R.
fwiw 5mm is the standard distance from top of the rubber mat to top of the pads on the iron platter.
-Steve
Referring to your helpful mag platter link I've always used the stylus gauge on the platter. The scale height is probably slightly higher than would be the case with the stylus directly in contact with the record surface, but I set for the middle of the SPU tracking force range and a couple of tenths of a gram additional are not going to cause an issue.
The cast iron platter is just so much better damped than the zamac platter that I can live with the minor magnetic deficit.
The cast iron platter is just so much better damped than the zamac platter that I can live with the minor magnetic deficit.
The electronic scale I'm using does closely approximate record height up off the platter mat. But I recognize that many/most scales do not attempt to duplicate this height.
It does make me drool for one of those Schopper non-mag / austenitic iron platters. Sigh. I think I saw one listed on Agon 2nd hand at $750.
-Steve
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I thought for a while about getting one, but at least two people commented on issues with the strobe ring, and it is also a lot of money. I might be inclined to get one if I were stepping up to something like an Ortofon Xpression LOMC cartridge, but for my two remaining SPUs (Royal N, Meister Silver) it seems overkill.
My recently ordered SPU A95 arrived at the local Ortofon dealer yesterday, and today I went and picked it up.
I also own a Meister Silver GM II and Royal N (Royal without the SPU head shell) and have to say even though the A95 is not broken in it is clearly a significant improvement.
The focus of this design is controlling/reducing unwanted resonances within the physical structure of the cartridge.
I guess all of the emphasis on resonance control paid off, it clearly resolves better that the Royal N which is no slouch, and has a more neutral tonal balance - the Royal sounds a bit brighter and not in a way that adds anything to the music, it just is. All round better.
The cartridge specifications included with the cartridge are slightly better than the specifications listed on the site. Tracking ability is now 80um @ 315Hz and 3g tracking force, compliance increased to 10.
It is also slightly lighter than the SPU A90 I had here for a while, or my Meister Silver which means that without a couple of dimes blue tacked to the arm tube of my Schick I cannot set the tracking force to the required value. I know now what I did not know when I ordered the Schick, and that is that I should have ordered the standard counterweight and not the heavy one.
For the few out there into SPUs this might be a must have, I have a more favorable initial impression of it than of its predecessor although as far as I know they are close to if not identical.
I also own a Meister Silver GM II and Royal N (Royal without the SPU head shell) and have to say even though the A95 is not broken in it is clearly a significant improvement.
The focus of this design is controlling/reducing unwanted resonances within the physical structure of the cartridge.
I guess all of the emphasis on resonance control paid off, it clearly resolves better that the Royal N which is no slouch, and has a more neutral tonal balance - the Royal sounds a bit brighter and not in a way that adds anything to the music, it just is. All round better.
The cartridge specifications included with the cartridge are slightly better than the specifications listed on the site. Tracking ability is now 80um @ 315Hz and 3g tracking force, compliance increased to 10.
It is also slightly lighter than the SPU A90 I had here for a while, or my Meister Silver which means that without a couple of dimes blue tacked to the arm tube of my Schick I cannot set the tracking force to the required value. I know now what I did not know when I ordered the Schick, and that is that I should have ordered the standard counterweight and not the heavy one.
For the few out there into SPUs this might be a must have, I have a more favorable initial impression of it than of its predecessor although as far as I know they are close to if not identical.
Attachments
Steve this is what Thorens advices do do with the Ortofon SPU carts, I use a Correx scale.
Volken
The output level is dictated by the number of turns in the moving coil assemblies along with the magnet strength. The 0.3mV is normal for all standard SPU, but excludes certain related mono models as well as the SPU-GT and SPU-GTE which incorporate transformers.
I generally set the tracking force between 0.75gm and 1gm low for the SPUs I use on my TD-124s unless I am using a digital scale on the platter in which case I set it pretty close to the nominal value.
I generally set the tracking force between 0.75gm and 1gm low for the SPUs I use on my TD-124s unless I am using a digital scale on the platter in which case I set it pretty close to the nominal value.
All three I currently own are 0.3mV, and coil dcr depending on model varies between 2 and 6 ohms.
The models with lower coil dcr have significantly better bass performance probably as a consequence of transformer interaction.
The published specs are often incorrect or out of date, I generally go with the leaflets that come with the cartridge for the most correct specification.
The models with lower coil dcr have significantly better bass performance probably as a consequence of transformer interaction.
The published specs are often incorrect or out of date, I generally go with the leaflets that come with the cartridge for the most correct specification.
Anybody here with EMT carts on their "clunkers" ;?) My friendly dealer gave me a donor cart for complete rebuild and EMT can either make it with spherical or line stylus . I'm too poor at the moment (another surgery) to send the cart out but will do it when the time comes because of legendary status of the cartridge. Some say that original spherical styli is the only true EMT , others that line stylus offers significant improvement . I was leaning towards spherical but now when I don't have to decide right away the old dilemma returns . TIA , L
PS , sorry for crapping the thread about SPU's
PS , sorry for crapping the thread about SPU's
I'm not really a fan of spherical styli and the cartridges equipped with them and I would even lump the spherical version of the SPU in there with the DL-103, Shure M75 and some others I have heard.
That said the line contact can be fussy about set up, azimuth and vta IMLE are both significantly more critical than with either spherical or elliptical. Weighed against better HF performance (lower tip mass) and lower distortion I think the increased care required in set up is a fair trade off.
That said the line contact can be fussy about set up, azimuth and vta IMLE are both significantly more critical than with either spherical or elliptical. Weighed against better HF performance (lower tip mass) and lower distortion I think the increased care required in set up is a fair trade off.
OK, so if the DCR is low but the output is high because of extra turns of wire on the coils, one might expect moving tip mass to be on the high side?
These cartridges all use different coils, wire and magnets. An output level of 300uV @ 5cm/sec lateral recorded velocity would not be categorized as high output. Hard to know what the exact internal differences are.. Here is what I do know:
The "equivalent tip mass" of the Royal/Royal N and the Meister Silver is 0.45mg and of the GM E II and A95 1.0 mg. All but the Royal are elliptical styli. I don't know how to interpret these numbers as I do not know whether this includes the mass of the cantilever or not. My understanding is that coil mass is typically just a few % of the total. Magnets are Alnico or Neodymium depending on model. The higher output models have more powerful magnets and less wire in the coils than the GM E which is the baseline elliptical model with OFC copper coils and alnico magnets. (Wire is OFC copper, silver, electrum or silver plated copper.)
To further add to the total confusion: Meaning of Effective tip Mass ?! - Vinyl Engine where meaning of equivalent tip mass is also discussed.
Save the Royal/Royal N none of these cartridges have usable frequency response that extends much beyond 20kHz.
A good deal of the specification information is included with the individual cartridges I own and may contradict information on the web which is also usually less comprehensive.
The "equivalent tip mass" of the Royal/Royal N and the Meister Silver is 0.45mg and of the GM E II and A95 1.0 mg. All but the Royal are elliptical styli. I don't know how to interpret these numbers as I do not know whether this includes the mass of the cantilever or not. My understanding is that coil mass is typically just a few % of the total. Magnets are Alnico or Neodymium depending on model. The higher output models have more powerful magnets and less wire in the coils than the GM E which is the baseline elliptical model with OFC copper coils and alnico magnets. (Wire is OFC copper, silver, electrum or silver plated copper.)
To further add to the total confusion: Meaning of Effective tip Mass ?! - Vinyl Engine where meaning of equivalent tip mass is also discussed.
Save the Royal/Royal N none of these cartridges have usable frequency response that extends much beyond 20kHz.
A good deal of the specification information is included with the individual cartridges I own and may contradict information on the web which is also usually less comprehensive.
OK, that's all consistent, thanks. Note that the etm of the Technics MM that I favor is 0.055mg.