Stax Cp-X Electrostatic Direct Pickup System

[decca4]

Hi Andy and other rare owners

Sorry for not responding earlier. I looked for a response for one or two weeks after my posting and when nothing happened I did not think that there would be an answer. Now I return somewhat red faced.

The few times (3 I think) that I have had the chance to listening to my STAX I did not notice any thinness in the treble, only a delicate, tuneful and precise one.

My Pod is totally dismounted. Someone had promised to adjust it some 20 years ago and then returned it in small pieces. It could probably be restored with much effort but as things stands I am aiming for a new one with a crystal oscilliator and a tube stage. Fortunately a friend of mine who is gifted in these matters has taken an interest in this cartridge and may come up with something very useful.

Although it is many years since I heard it it is still in fond memory and in my mind the best that I have ever heard. Previously I used a Kouetzu Onyx. Very smooth and delicate but with no life or temperament. This was replaced by a Garrot Decca and I have stayed with various Deccas until now when I am trying out an IKEDA. I have also had a WIN strain gauge which was interesting but not really a winner in my system.

Your pictures are excellent and your try with the Souther most interesting. You say that you experience noise with the Souther. Here is an idea why: The cable and its capacitance is in parallel with the capacitance of the cartridge. If this cable is lose and can move anything that makes it move will probably induce a signal. When you touch any part of the new arrangement you are probably also creating a signal. I suggest that you ask someone clever. I will ask my friend for an explanation.

Are there by chance any pictures of your friends arrangement with the STAX in the RABCO?

I have some written material in English (specs and explanation of the principal, 3 or 4 pages written by STAX) which I could scan and mail to anyone interested.

I promise not to wait another 6 month before checking back to this thread.

Stefan

[decca4]

A friend of mine is very interested in trying to find a CP-X. Does anyone know one that is up for sale?

Stefan

[tubes4life]

Hi Stefan,

Ever since I reinstalled my Stax last December, I've not been able to take it out again. I tried it on two systems with three turntables - Thorens 125, Goldmund Studio and Panasonic SP-10. Eventually, I decided to let it stay on the Panny. As I have several other cartridge/tonearm/turntable combinations already set up, I have plenty opportunities for comparison. So far the Stax/Panny combo has certainly gotten played as often as the others.

For some reason, this time around, I found my POD-X quite stable needing hardly any adjustment during listening sessions, long or short. The major gripe I had in the past was an annoying thumping sound through the speakers when records being played are off center or otherwise imperfect. I finally found the culprit. It's related to the VTA. When VTA is "correctly" adjusted, the thumping noise simply vanishes. Of course, the tracking force has to be set at 1gram as specified by the factory for optimum performance.

I'm sorry I don't have any picture or specifics for the Rabco setup. I tried to re-establish contact with my friend who had it done but was informed that he had passed away a few years ago. He was the one who told me that the total capacitance of the Rabco internal wiring and the additional interconnects

had to be exactly right otherwise it wouldn't work, as I eventually found out for myself during my Souther experiment. I wasn't happy with the outcome of Stax/Souther but before I quit fooling with arm swapping for good, I'll give the Versa Dynamics arm a try. Again this requires a suitable adapter for mounting. I will have to get a machinist to do the job for me. If I don't get better performance out of the combination, I'll just have to put up with the UA-7. To be fair, I'm really quite happy with the CPX on the Stax UA-7 with its dedicated arm wand, now that I've solved the major annoyance.

I'm very interested in your friend's proposal of a stable detector/oscillator circuit for this wonderful cartridge. I hope it will eventually happen. I don't know why Stax didn't do somthing similar, but then I heard or read somewhere that the oscillator has to be broadly tuned and x'tal might not be ideal. At present I would gladly just settle for a good low noise tubed voltage amp with 10db gain to replace the stock FET circuit in the POD box.

For those who wish to upgrade the performance of their POD, there is an article in Japanese with schematics and all on the internet. Unfortunately, it's very difficult to make sense out of the machine translated text in English.

http://web3.incl.ne.jp/tetsu/c8dekirukana/podrstr.html

I probably have the same hand-written instructions in English provided by Stax. Thanks for the offer. Is your friend looking for just the cartridge or the complete system which includes the cartridge, dedicated tone arm and the Demodulator/Oscillator? I haven't seen them offered on the used market for years.


Regards,

Andy

p.s. How do you like the Ikeda? Which model is it? How does it compare to your Deccas? I'd love to try one of these unusual cantileverless MCs, but do not want to have to give up my right arm for it. I already have a Ikeda designed Jeff Rowland Complement tonearm waiting here just to be used for the purpose.

[album]15571[/album]
my final setup for the CP-X for now...

[decca4]

Hi Andy

I am glad to here that the STAX CP-X is still you favourite. It inspires me to get mine up and running again. When looking at my Pod wreck I found that it is absolutely possible to get back in shape. That will be my first priority. I will probably change all the electrolytics and the cole resistors.

My friend has grown some confidence in my judgement regarding worthy stuff after pointing him in the direction of the Futterman OTL H3AA and the very able Yamaha NS-2000 (very much better than and different from the NS-1000). I also helped him find these items. Now he believes I can find any rare item. He reacted favourably to the intellectual challenge of designing a better POD. However I think that finding him a CP-X will speed up matters and secure that he actually takes on this job. He would of course prefer that he could by the complete system incl tonearm. However just getting him the cartridge would most probably trigger things.

I was sorry to hear that you friend past away. As it is some years ago do you think that it is still inappropriate to inquire as to what happened to his stuff?

Thanks for the Japanese link. I also tried to do a machine translation both in english and in swedish. Although it is guess work what he says it is still useful info. In particular I was pleased to see the picture of the inside of the cartridge. That spares me destroying mine. Furthermore the circuitry is useful to see when embarking on the new project. I will keep you posted as to what happens as regards this.

Is the Pannasonic SP-10 more or less the same as the Technics SP-10? I used to have a Goldmund many years ago. At the time I found it very good but a bit to lean and would perhaps not marry well with the CP-X.

I have used a Garrott modified Decca IV for many years. It is extremely fast and gives a very lifelike presentation of the music. The midrange is tuneful and real when it comes to voices. It is not easy to live with and requires proper matching regarding tone arm and set up. You can also run into hum problems. There is one thing that I have found that this cartridge does better than any that I have heard. That is it's ability to present the whole tonal spectrum equally during dynamic passages. I believe that this quality is what makes the cartridge so life like. The top end is not anything to write home about. However you like it because of it's strength and have to live with it's weaknesses.

The IKEDA that I presently use is the model 9C/V and is mounted in the RABCO. I tried another IKEDA many years ago and was very much taken in by it. It had most of the qualities of the Decca without the quirks. However there was no way that I could make it track. The tone arms I tried was the Forsell and another linear tracker. I now realize that these arms were the wrong choice for the IKEDA. There are no problems whatsoever with the RABCO. The sound of the one I presently use is not as impressive as I remember the sound of the other one. It is sweet, tuneful and the best moving coil that I have heard. However he dynamics are not nearly as dramatic as that of the Decca in my mind. Neither is the speed. I would have no problem living with this one as the musical presentation is very realistic and involving. However if you remember the sound of the Decca and in particular that of the CP-X one want's more.

My present system is: Thorens TD-124, a homebuilt tube pre amp, the Futtermans and the Ymaha NS-2000. I also have some modified Beveridge 2SW which were my speakers for some 15 years. These are resting at the moment although I have plans to put them back into service if only to check if they are as good as I remember them. What components are you running?

Cheers Stefan

[tubes4life]

Hi Stefan,

I'm sorry I used Panasonic SP10 and Technics SP10 interchangeably. I always thought they were the same and that I had a Panasonic turntable but the other day when I was taking pictures, I noticed that it had a Technics logo on it.

Goldmund is a wonderful table but somehow the CP-X and UA-7 just don't go with the table aesthetically. They look puny and somewhat lost on the table.

SC4E has been one of my favorite cartridges, stock or modified. I had one with a line contact stylus and it performs very well indeed on my Versa 1.2 table. As you said, Decca just sounds more dynamically realistic than its competitors. It's certainly one of the most musical sounding cartridges I've ever used. Residual hum used to be a major problem with the Decca but now, after I upgraded my AC power supply to dedicated lines with "isolated ground" outlets, I no longer experience any hum at all with them. They are as quiet as any MC or MM cartridge.

I wonder why the Forsell arm is not as good for Ikeda as the Rabco. However, I used various Deccas with Rabco for a while and as I remember they performed very well together also. I still have my Rabco and someday soon I'll set it up again and see how it stacks up with the more modern air bearings.

I used a pair of 3aa to drive my KLH9s for a while. Wonderful amps. I waited over a year for them as they were hand made to order by Julius Futterman at the time. Everybody had to wait in line since Futterman couldn't be rushed. Everything was practically hand-made by him with the help of his brother-in-law. I used to visit his tiny workshop on Broadway in NYC. He had this huge hand wired "burn-in" board on one of the benches with twenty or thirty output tubes all plugged in and burning at the same time. Each individual tube was then tested and data recorded in his black notebook. In the corner of his workshop there was this tub of tar cooking his hand wired AC transformers. My pair of 3aa was taken by force from me by a friend who just couldn't wait. I got a 3a which was one of the Model 3 trade-ins refurbished and upgraded to the 3a status by Julius himself. Looked much better but didn't sound as good as the 3aa. I put my name back on the waiting list but Julius never got to mine before he passed away suddenly.

The Beveridge 2SW you have is a true classic. I heard them at one of the CES shows in the 80s. The cartridge used a Decca at the demo. Sounded great.

I'm currently using Infinity IRS-Beta and Quad 63 in two different rooms. All my electronics are tubed except for the cross-over and the amp that drives the Beta woofer columns. I have a few turntables hooked up permanently and can be called to service at the flip of a switch. I'll probably post the details of my system with some pictures in the readers systems forum in the near future.

Andy

[Alec124c41]

My SP-10 label reads "Technics by Panasonic."

Cheers,
Alec

[decca4]

Hi Andy

It's most interesting to note that our respective "search enginges" or ears are looking for similar stuff.

I have allways heard a lot of good things about the KLH9 but never had a chance to here them. What a pity.

The SC4E is a wonderfull cartridge redardless of if it is modified or not. I feed all Deccas into a 1 meg Ohm load in the Pre amplifier. This is unconventional I know but it realy opens up the cartridge. Please try and see or here what you think. A friend of mine who is an audio enginere gave me this tip. The better my electronics were the better this load worked.

The reason that the IKEDA does not work in the Forsell or other simiar arms is probably that the IKEDA is rather stiff in the lateral complience mode. The IKEDA is 6 x 10 and the SC4E is 30 x 10 which in itself is extremely complient. They seem to have the same vertical complience 6 x 10.

It is almost spooky to come across someone who has so many of rather rare component as I have. You even have the Futtermans. I don't know what the difference is beween the H3AA and the H3A. Do you? I had a similar experience with my first pair of the Futtermans as you had regarding someone grabbing them. Ther was a Norwedgian that was interested in buying my STAX ESL-6 fullrange electrostatic speakers. He came and listened for a full evening and than said that he wanted to buy my Futtermans that I used to drive the STAX with. I replied that they were not for sale and he responded that would surely be a matter of price. I said that I could not contradict him on his statement. He then followed up by giving me a silly offer and so they were gone. The pair I am using presently was bought two years ago for the purpose of restoring and passing on to Japan or elsewhere. Howeve when listening to these there is no way that I will let go of these. I will not let any Norwigian or anyone else with funds into my flat.

It must have been a fantastic experiance to have met Julius Futterman. I wish that you will have the oporunity to lay your hands on a pair of the H3AA.

My Beveridge will hopefully be up an running in a couple of weeks. The woofer system I use is allmost the same as what you use for your IRS-Beta. Mine are a copy of the collums used for the IRS but mine uses 5 12" woofers per side with the active feed back system.

Sorry for the spelling. My spelling corection system does not work.

Best Regard

Stefan

[tubes4life]

My SP-10 label reads "Technics by Panasonic."

Cheers,
Alec

Hi Alec, Just out of curiosity, I checked in Wikipedia for the history of Panasonic and Technics brand names used by Matsushita and I found this:

In 1927, the company founder adopted a brand name "National" (ナショナル, National?) for a new lamp product, knowing "national" meant "of or relating to a people, a nation."[5] In 1955, the company labeled its export audio speakers and lamps "PanaSonic", which was the first time it used its "Panasonic" brand name.[6] The company began to use a brand name "Technics" in 1965.[6] The use of multiple brands lasted for some decades.[6]

No wonder we have different logos on our tables. One thing is for sure though - Technics is no different from Panasonic.

Regards,
Andy

[tubes4life]

Hi Stefan

I never tried any load over 47k for Decca. I may try it someday. Will let you know how it turn out. Thanks for the tip.

Ikeda is not alone in the stiffness department. Stock Decca SC4E probably has the highest lateral compliance of all Decca cartridges. However, the one modified by Len Gregory has a very stiff compliance both vertically and laterally and this causes some compatibility problems with my Versa Dynamics arm which works perfectly with the stock version. Incidentally, my Nagatron AU-2000 ribbon cartridge is spec'd at 7cu. It has a SME type headshell connector but works rather poorly in most low/medium mass 9" arms with detachable headshells. I was flabbergasted at the sonic difference it made in a 12" high mass arm.

I know a little about the Futterman OTL amplifiers. The first Futterman OTL which gathered wide attention was the Model 3 stereo version which used eight 6HJ5 output tubes. According to Futterman the production run was very small. Only 300 chassis were made. This is the only "commercial" version which was marketed by Futterman himself. The business didn't take off since the whole hifi industry had gone solid state(mid 60s). Futterman then set up a small workshop in the upper West Side New York hand building his amps for the very few tube fanciers still left. He said most of the 300 pcs were sold to Japan. All the subsequent Futterman amps built himself were on DIY-type of chassis without cage. If my memory still serves me, there was this huge stereo 3a version using four 6KG6s on open DIY chassis, then came the final monoblock 3aa version using six 6LF6s per channel. Not too long before Futteman's death, Harvey Rosenberg of New York Audio Labs acquired the rights to manufacture the OTL amps under the name Futterman. All of the newer model made by New York Audio Labs used printed circuit boards.

My 3a was built on the commercial chassis as the 3. It has an out-sourced power transformer unlike the later 3a and 3aa with transformer hand-wound by Futterman himself. I like how my 3a looks but when driving the KLH9s it sounded subtly dry and thin compared to the 3aa and the later NYAL models. Several years ago I was at a used hifi shop listening to a pair of Stax Electrostats. I didn't pay any attention to the model number but they were

rather tall. I liked the sound so much so that I went to the back of the speakers to see what was driving them. I was surprised to find a Futterman 3a just like mine except it was sitting on an add-on chassis full of capacitors. So I know there is still hope for mine.

Hope you can get your Beveridge up and running soon. Do you still use the build-in woofers when paired with your woofer columns?


Cheers,
Andy

p.s. Thank you for bringing up Futterman. I took the 3a out of storage. It's been close to 10 years the last time I used it with the Infinity RS-1. I dusted it off and took a couple of pictures last night and this morning I put it on the variac for a couple of hours before I hooked it up to to the Quad 63. With FM broadcasting, it sounded a little shap at first but after a while It started to sound good. Clear blue sky all the way. No cloud, no haze, no veil, just wonderful! I'll try it with the CP-X this evening and see how it fares. There should be 8 output tubes, but you only see 4 in the picture as I accidentally broke one tube a few years ago. Since the pair are wired in parallel, I removed the other 3. The power dropped to 45w from 90, but quite adequate for the 63.

[album]15618[/album]
Futterman Model 3a OTL Amp

[decca4]

Hi Andy

Ones more we have followed similar paths. I sent my Decca 4RC (the conical needle) to Len Gregory for re tipping some 2 years ago. I also ask him to remove the LC linkage sitting inside the cartridge. My reason for asking this is that I at the time I intended to build a dedicated pre amp for the Decca with LC linkage inside the pre amp. To build such a freak turned out to be more complicated than I had anticipated so it is another project waiting for materialisation. The LC linkage inside the cartridge takes care of the high resonance of the coil that scans the lateral movement. There is also a resonance in the coils scanning the vertical movement. As the resonances are rather high up, 65 kHz as I recall it, damping is perhaps not necessary. As I know none of the modern ones have any compensation. So the plan is now to try it out in the RABCO within short. The original 4RC has half the compliance (15) of the SC4E in the lateral mode and 4 instead of 6 in the vertical mode. I have no idea of what my modified 4RC has.

The info you have on the Futtermans is most interesting. I have never seen or listened to any other than the H3AA and the NYAL OTL 3 here in Sweden. Ones we compared those two and the H3AA came out as the clear winner at this occasion. I have also listened to the OTL 1 at one occasion when I was invited by Harvey Rosenberg to his home. He was a most interesting and entertaining host. The stories were endless and his glowing dedication to the OTLs were very apparent. I understand that he was a controversial person in the industry however I feel fortunate to have had the chance of spending an evening together with him and having the opportunity to listening to his very colourful language. I honestly don't recall much of how it sounded other than good.

Your H3A looks really nice. Are those tubes the 6LF6? My mono H3AA were rated at 60 w into 8 Ohms so if your amp has the same tubes as mine your are probably getting less than 45 w. As I racal it the OTL-3 were rated at 65-70 W. Another factor to consider is that using fewer tubes will rais the output impedance of the amplifier so using more will improver matters. If you cannot find a replacement for the broken tube please let me know and I will see what I can do.

The subwoofers that came with the Beveridge 2SW are nice to look at but not really suitable at all so they do a better job staying away from any listening room than being included in the system.

It will be most interesting to here how the STAX and the Futtermans sound when joined together.

I intended to post some pictures but don't know how to do it. Can you give med some hints?

Cheers

Stefan[/img][/quote]

[decca4]

Hi Andy

Ones more we have followed similar paths. I sent my Decca 4RC (the conical needle) to Len Gregory for re tipping some 2 years ago. I also ask him to remove the LC linkage sitting inside the cartridge. My reason for asking this is that at the time I intended to build a dedicated pre amp for the Decca with LC linkage inside the pre amp. To build such a freak turned out to be more complicated than I had anticipated so it is another project waiting for materialisation. The LC linkage inside the cartridge takes care of the high resonance of the coil that scans the lateral movement. There is also a resonance in the coils scanning the vertical movement. As the resonances are rather high up, 65 kHz as I recall it, damping is perhaps not necessary. As I know none of the modern ones have any compensation. So the plan is now to try it out in the RABCO within short. The original 4RC has half the compliance (15) of the SC4E in the lateral mode and 4 instead of 6 in the vertical mode. I have no idea of what my modified 4RC has.

The info you have on the Futtermans is most interesting. I have never seen or listened to any other than the H3AA and the NYAL OTL 3 here in Sweden. Ones we compared those two and the H3AA came out as the clear winner at this occasion. I have also listened to the OTL 1 at one occasion when I was invited by Harvey Rosenberg to his home. He was a most interesting and entertaining host. The stories were endless and his glowing dedication to the OTLs were very apparent. I understand that he was a controversial person in the industry however I feel fortunate to have had the chance of spending an evening together with him and having the opportunity to listening to his very colourful language. I honestly don't recall much of how it sounded other than good.

Your H3A looks really nice. Are those tubes the 6LF6? My mono H3AAs were rated at 60 w into 8 Ohms with six tubes per side so if your amp has the same tubes as mine your are probably getting less than 45 w with just two tubes. As I racal it the OTL-3 were rated at 65-70 W. Another factor to consider is that using fewer tubes will rais the output impedance of the amplifier so using more will improver matters. If you cannot find a replacement for the broken tube please let me know and I will see what I can do.

The subwoofers that came with the Beveridge 2SW are nice to look at but not really suitable at all so they do a better job staying away from any listening room than being included in the system.

It will be most interesting to here how the STAX and the Futtermans sound when joined together.

I intended to post some pictures but don't know how to do it. Can you give med some hints?

Cheers

Stefan[/img]

[/quote]

[tubes4life]

Hi Stefan,

According to Markse the LC or RC network is re-introduced in the London Reference. I have 3 SC4Es two of which I opened didn't have any compensating elements. All the 4RCs I opened had the network. Nothing in MK V and up.

Markse recommended John Wright for Decca refurbishment. I'll try him next. I'll also give Expert Stylus a try someday.

Harry Rosenberg was a colorful person. I visited him several times in Croton-on-Hudson where his factory was. Later he moved to Connecticut somewhere. I was there once. He was heavily into triode single ended equipment at the time. I remember his 7w Wavac drivining the Tannoy Westminster Royal to full volume and sounding wonderful. That was the last time I saw him before he passed away.

The wattages for the Futtermans I quoted were probably measured at 16 ohms. The official published power outputs are 60w for 3, 90w for 3a and 120w for 3aa. Inflated? Maybe. But these were the claimed figures by Futterman. However, I can't vouch for it since it was so long ago and my memory may not be trustworthy.

Your're right about the increased impedance with reduced number of tubes. The 3a uses 6KG6s. Thanks for the offer anyway.

The Stax and Futterman must sound good together since I still remember my departed friend used Stax, Rabco, Thorens, Futterman and Quads. I don't remember the preamp, however.

The instructions to upload pictures and to use them in your posts are available in the FAQ of VE. The following info I lifted from the FAQ may help you.

How do I upload images to my personal gallery?
Navigate to your personal gallery using either the my account link on the home page, the profile link in the forum or the personal gallery link on the gallery page
To upload images click the upload pic button and follow the on screen instruction

How do I add a gallery image to a forum post?
(1) Browse to the gallery page that displays the full size image that you want to display in your post
(2) Copy the code in the 'BBCode' box under the image
(3) Paste the code into your post where you want the image to display
note there is no need to add image tags or any other code, just paste the code exactly as shown in the BBCode box

There are other ways to post pictures on the forum. I've never used them. Maybe other members can help you on this. Lookin forward to seeing your pictures.

Regards,
Andy

[decca4]

Hi Andy

I have the 4RC. C4E and the SC4E. In my C4E and the 4RC there was a LC compensation. I have not looked inside the SC4E. It is interesting info that the Reference has one also.

The H3AA was rated 60 W into 8 Oms and I was told 120W into 16 Ohms. So your figures makes more sense if valued into 16 Ohms.

I have not sent anything to Expert Stylus but talked to bot father and son over the phone. My impression is that they are very dedicated to the cause. It seems this is where most Deccas are sent by others for retipping so it would make sense to sent it to them directly. I have it from reliable sources that the needle in the reference is made by Expert Stylus. It is designed by the father and called Paratracer. I have plans for sending one of my Deccas there for the purpose of puting on a Paratracer. There is a big following of the Decca cartridges. If you go there just search for Decca topic and you will find it.

Do you know roughly how many H3AA Julius Futterman made?

Thanks for the tip about posting pictures. I will give it a go shortly.

Do you know of any people to contact in the States that could possibly put me in the right direction to find a Stax CP-X?

Cheer/Stefan

[tubes4life]

Hi Stefan,

Markse, one of the Decca gurus on this forum, told me that his SC4E had the network. The two I opened didn't. I have to say that I did send mine back to Decca for quality checkup in the 70s. It's very possible they removed the network at the time.

I have no ideas how many sets of 3aa were made, but I was told Futterman only made a couple of pairs per month. I had to wait 1-1/2 years for mine. BTW, I have the schematics for the 3a and 3aa and also their setup instructions. If you or anyone else should ever need them, please let me know.

If you go through the earlier posts of this thread, you'll find there are a few people who still have the CP-X. They may give you some leads or perhaps even be willing to part with their own.

Cheers,
Andy