SPU Cartridges and Transformers Thread

[Panicos K]

Originally Posted by brianco

But they were used in-line usually at least 1m from the cartridge, giving that length (of typically low quality cable) for an extremely low level signal to be interfered with by whatever is in the vicinity by way of magnetic flux, RFI, whatever, whereas the "T" version of the cartridge had but 1.5 cm approx for such problems to gain entrance to the signal-path. The trade off was of course extra mass.

The mass of the SPU-T headshell was not the same as the GM.The GM had a thick and heavy brass(or lead) spacer inside,while the T had a thin brass spacer(or tall aluminium washers).The total mass in both cases was around 32gr .

A good way to use these miniature transformers is at the exit of the internal arm wire inside the turntable plinth.From there you can continue with the arm cable as usual.

I'm trying unsuccessfully to upload a picture showing these transformers and the innards of 2/15K.I hope to manage soon.

[kevinkr]

I'm pretty familiar with the sound of the 2/15K transformers integrated in the SPU G/T or G/T E.. They are pretty good, but the combination of external transformer with the GM E easily output performs the G/T E in some areas - particularly in LF extension, depth of image, and HF extension - no audible hum either.. My Schick arm has captive cables and as it is still under warranty I'd rather not modify it..

Note also that the G/T E based on a quick measurement is very slightly heavier by a gm or so than the GM E II.. Both are >30gms... I have the higher mass weight on my Schick arm..

As an EE I would be likely to design my own head amp if I chose to go that route, but thanks for the MPP reference.. I actually prefer transformers and have an all tube signal path that I would like to keep that way..

[Panicos K]

As brianco says,SPU's are popular in Grmany,but not as popular as they are in Japan.It is actually the Japanese that have kept the SPU alive till today.

This is the reason why you will also find some ortofon transformers that are only recently available in many countries but were selling in Japan a long time ago,also they are made in Japan.

These may be a good choice for SPU but they are not cheap today.

[GaryB]

Kevin,
I've got no hands on experience with the SPU but there is quite a bit of discussion on the web. There's a very nice German web page on the use of Siemens/Klangfilm for MC step up duties that claims the VL23 is the bomb when it comes to SPU pickups. It's a 1:30 transformer with impedance ratio of 3.2ohms:2500ohms. But these transformers have already been discovered and aren't cheap. There's a finished step up transformer box for sale on ebay (not mine) for sale for $699. Perhaps if you keep your eyes open you can find the raw transformers for less.

If you're willing to pay other people some big bucks then I've read good things about Auditorium23 and Silvercore transformers.

On the other end of the price scale, I've seen one person say they liked the Edcor RMX-1, a modern day clone of a 1953 RCA ribbon mic transformer. It's got very high gain at 1:37 and goes for around $23 direct from Edcor. As with most transformers, these are sensitive to loading and one person liked these loaded with 150k ohms instead of the "normal" 47k load.

---Gary

[kevinkr]

Today I ordered a pair of Lundahl LL1941 from K&K and will report back once I have had them for a while.. In the mean time the current UTC HA-100X transformers sound really good. I'm hoping the Lundahls will better them in bass extension and should result in an even lower noise floor since their primary and secondary DCR is about 1/10th that of the UTC. In theory I should expect a slight enhancement in resolution, but the current transformer is good enough that is hard to imagine. Worst case I will just buy these.

The SPU is now fully broken in, and in combination with a Schick arm and my TD-124/II gives me the best vinyl reproduction I have ever owned. Shame it took so long..

[kevinkr]

I decided to split my SPU posts off of my old TD-124 thread as they are OT in that thread and I thought would eventually end up lost.

Hope this thread is useful to others besides me.

[Telemann]

Well done. I have a Schick arm coming to me in October, and will benefit hugely from you going to the trouble of finding the best solutions!

[kevinkr]

Much appreciated.. The SPU is really good and I just want to make sure I end up with the most suitable SUTs I can afford. There are a lot of extremely expensive options out there, and a limited number of DIY solutions which might or might not be competitive. The 1941 has a good pedigree and the technical description sounds promising, ultimately it depends on how it sounds in my system of course.. The big problem for me is that almost nothing has been written about the performance of this transformer so the purchase was entirely on faith that good engineering is going to give me what I expect..

The 1941 is based on a cut cobalt amorphous core and the 1943 on permalloy. The 1941 is supposed to offer the greatest resolution, and the permalloy 1943 is targeted at those who prefer its tonal characteristics. (I currently have permalloy transformers in several locations in my system and find them a big improvement over grain oriented silica steel in resolution, and distortion, but the amorphous core is supposedly better still.)

Lundahl 1941 data sheet http://www.lundahl.se/pdfs/datash/1941.pdf

Lundahl 1943 data sheet http://www.lundahl.se/pdfs/datash/1943.pdf

They are higher gain versions of the 1931 and 1933 respectively.

[kevinkr]

I picked up the transformers at the post office this morning and plan to wire them up tonight and give them a listen.. Can't wait..

[kevinkr]

I've only be listening to the LL1941 for a few hours over the past evening and today, but I will say they are quite good.

They are very neutral sounding and perform well right to the bottom of the bottom octave. They sound quite extended. I'm not sure they have much personality, they are quicker sounding, image slightly better and seem to present a slightly deeper sound stage than the HA-100X I have been using. The HA-100X has a warmer, more palpable midrange, but the trade off is a clear loss of detail - subtle but there, and their bass performance is bested by the Lundahl as are the extreme highs which are clearly more present.

I'd say these are a good choice with the SPU Classic GM E MKII at least.