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SET Asylum Single Ended Triodes (SETs), the ultimate tube lovers dream. |
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SET Asylum Single Ended Triodes (SETs), the ultimate tube lovers dream. |
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In Reply to: ELECTRAPRINT Single-Ended Output Transformers, DIY Modifications posted by drlowmu on July 15, 2016 at 08:26:00:
The ending paragraphs got cut off as posted, am not able to edit it. So, here is a re-post, complete.Jeff
DIY Modifying Single Ended ElectraPrint Output Transformers
This is a UN-authorized set of 2016 mods, to ElectraPrint SE output transformers, that I want to share with others.
As I see it, there are two areas where improvement is needed in these SE transformers.
(1) First, it seems as if all the laminations are held together with steel ( magnetic ) bolts, 2.5 inches long and 8/32nds thread. My friend in the U.K. tells me even his deluxe "extra interleaved, Partially Silver Stranded Secondary" SE Output has STEEL bolts holding the end covers.
These need to be converted to brass bolts and nuts, as per Mike LeFevre's early Sound Practice article on "Transformer Potting". Mikey explains, steel hardware through the core adversely RAISES the core's exciting threshold.
(2) The stock lead wiring on the Primary and the Secondary is a HIGH LOSS area, that begs to be fixed. From what I see, its 22 AWG wire, and it looks very ordinary to me. There are SEVEN strands of wire internally, comprising each lead.
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The first FIX, steel bolts and nuts :
(1) Measure the bolt length. Mine were 2.5 inches, threaded 8/32nds, and "Ace Hardware" carried only up to 2 inches long in brass. Go to eBay and buy a pack of 12 brass machine screws ( search words ) - which can be landed to your door for about a dollar a bolt. More than a pair of these outputs??, order from the 25 pack auction, even less per bolt, shipped. Order 8/32 brass nuts, and if easy, a brass lockwasher too.
CAVEAT: When you replace the steel with brass, it is ULTRA CRITICAL to EVENLY tighten the laminations, and it must be tightened snug enough to hold the laminations in place, but do NOT wildly over-tighten the bolts. Very very firm, and EVEN torque is the key.
The second FIX, 22 AWG lead outs :(2) Purchase multiple colors of 16 AWG teflon coated wire. Best would be stranded silver, hard to find, costly. Excellent bang for the buck, and good enough for this quality of an output, is M22759/11 16, which is copper stranded, silver plated, teflon jacketed, eBay, Apex Junior ( Steve ), etc .
Use TWO 16 AWG leads in parallel, in place of each single stock 22 AWG ElectraPrint stock lead wire. (1) Take care to run equal wire lengths, and (2) maintain the SAME DIRECTION of both leads in a pair, relating to how it was manufactured. I cut my 16 AWG Mil Spec wire leads into 13 inch long lengths.
Cut the stock lead 3 inches out of the bobbin. This will leave you with about an 11 inch piece of stock 22 AWG wire to PRACTICE upon.
CAVEAT : Very very IMPORTANT : Do a minimum of three to five practice wire strippings on the cut-off eleven inch leads, until you can strip it twice in a row with six to seven of the seven wire strands left INTACT, after you have pulled off the insulation.
( I goofed and did no practice runs, got FIVE of the seven strands left, which is mediocre, to be AVOIDED. PRACTICE ( on the cut-off long pieces ) makes PERFECT !! Please.. DO NOT skip practice stripping !! ) Next, the surgery :
On the three inch stub, coming out of the bobbin, carefully strip the wire 1 1/2 inches from the end, to get ALL SEVEN, six minimum, strands left intact. Wind the stock 22 AWG wire three times ( minimum ) around the paralleled 16 AWG newly added leads. Use good stuff, Wonder Solder Signature, or Cardas Solder to solder this joint. Heatshrink the entire joint . I would add a label, INSIDE the bell cover, or on the bottom of the trannie's core, to designate in future years which leads on the Primary and Secondary are which "new" colors ( the double 16 AWG colors ). Designate "Anode and B+"colors on Primary and "Ground and 8 Ohms etc" for the Secondary.
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I have a question for any of you who have read this through. We can't control the winding wire, but .... Would you run the wire from the amp to your loud speaker with 22 AWG wire ? No, of course not !! Double 16 AWG is the equivalent of 13 AWG, without the negatives of the usual "large wire" sound.World class Siltech wire for audio is also about 13 AWG. So we are emulating that amount of wire. Siltech is unobtainium to a DIYer, made of silver with maybe some gold in it. First Class stuff, unparalleled in performance. To share this conceptually, the perspective is - think music and think "instantaneous PEAK currents," in and out of the output transformer .
On amps we now build, the ear easily hears "all" of this. Many thanks to Dennis Fraker, for his ingenious help. Also, see my prior 2016 Forum post on Power Transformer lead-out re-doing.
Please share with us your direct actual listening results. 'No need for EE theory here, HOW do these two changes sound to you, upon hearing it ??? Have fun.
Jeff Medwin
http://www.siltechcables.com/
Edits: 07/20/16 07/20/16
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Follow Ups
- Correction, above Post - drlowmu 13:41:51 07/20/16 (0)
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