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Sunday, December 8, 2013

Serious Silver!


After my previous positive experiences with silver transformers and silver LCR RIAA coils, I ordered a set of silver transformers from Lundahl for some cost no object all silver power amplifiers.

A pair of silver LL1691BAg/70mA, the silver version of the LL1691B which has proven to work well in 211 amplifiers.

These will be used along with LL2746Ag interstage transformers, the silver version of Lundahls relatively new LL2746.

These transformers are on a larger core as Lundahls other interstage transformers, suitable for a serious driver tube which will be another 211 in this case. The tubes which will be used in this amp will be 2 ELROG ER211 per channel. To make the silver theme complete the amp will use silver wiring throughout, including tubes with silver wiring in the base. Of course the amp will use an equally suited input transformer, the LL7903Ag. Here a photo of the transformer set of one channel:

The LL1691BAg transformers are big blobs of silver, here in comparison with the LL1660Ag, which works nicely in a silver line stage which I built earlier this year.

Stay tuned for posts about this cost no object amplifier. I will also write another detailed post about the Elrog tubes which will be used.

Besides this rather high power amplifiers I also plan a 45 amp at the other end of the power spectrum. Since the 45 has proven to work well as driver for the 45 as described here, it will be 45/45. Using the LL2746/30mA which fits well for this application. This is the transformer set for the 45 amp:

It will use the LL1682Ag, a silver version of the LL1682:

As can be seen in the photos, these silver transformers finally come with much better quality solder terminals:

Sturdy solder lugs are used on fiber glass boards. Smaller lugs for the interstage transformers and primaries of the output transformers:

The solder lugs for the speaker connections of the output transformers need larger lugs with a center hole of sufficient diameter for the thicker silver wire used in the output windings:

Some detailed shots of the wires coming out of the winding stacks, here the LL1682Ag:

The output transformer for the 211:

The primary connections of the 211 transformer:

Some samples of the enamelled silver wire which is used:

Close up:

Stay tuned for updates on these exciting new projects!

Best regards



  1. I anticipate these being the largest amps on your website, 4 chassis?

  2. Hi!

    Yes these will be the largest amps I have shown only site yet


  3. Hello Thomas,

    on one of the transformers we can read P-P. is this an push pull design? Where will this be used?

    Best regrads,

  4. Hi Bernd,

    sorry, but I will not share details about the intended circuit for this transformer yet ;-)


  5. Thomas,

    I was wondering why you use the Tribute OPTVC with silver wire and Finemet core if the "copper" loss is almost 12%?

    Tango dos 0,2dB - 0,3dB (4% - 7% loss)

    1. Hi!
      It is not about reducing loss. I have compared the same transformers with identical winding arrangements. In these the silver makes a negligible difference in DCR. The Silver versions always sounded remarkably better. I don't know yet what it is that makes this difference. While I hear only small differences when I compare silver hook up wire against copper, it makes a much bigger difference in transformers

  6. I think you have to start with a good designed transformer, not a transformer silver/copper with high wire loss. It makes no sense to invest in silver and a finemet core if you have not a 95% or better transfer design. Of course a good frequency response and good square wave response (= absensence of resonances)

    1. Hi!
      There is more to transformer design than just wire loss. I have evaluated many transformers and I select them based on the overall performance, sound and measurements. The Tribute OPTVC which I think you are referring too is unique in that. I am not aware of any suitable alternative to it

    2. Sorry, but there is no magic involved in transformer technology. I understand that there are not many winders who make a OPTCV but i.m.o it would be a shame to sell a "quality" transformer with a loss of 12%. But, if it would be a cost no object myfi, all is possible.

    3. Hi!
      No problem if these are not to your standards. Also nobody claimed any magic involved. These transformers are existing units which I tested and tried and they work nicely. I don't know about which alternative you are talking and if it exists at all. I had been approached by transformer winders in the past, especially one who seeks lowest possible losses. But the results I saw and heard were not impressive. So, anybody can follow his way. I have no problem with that. But I don't give much for theoretical claims about superiority or flaws if not proven to me. So lets leave it at that.