|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
71.50.19.0
This is a UN-authorized pair of mods, to ElectraPrint SE output transformers, that I wanted to show you.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.
---------------------------------------------------------------------------------
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 ½ 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.
-------------------------------------------------------------------------------------
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 !! WHY have 22 AWG as lead outs into and out of the Output Transformer???Double 16 AWG is the equivalent of 13 AWG, without the negatives of the usual "large wire" sound. Siltec wire is 13 AWG BTW. 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
Edits: 07/15/16 07/20/16 07/20/16Follow Ups:
I told Jack to use brass hardware years ago...apparently he didn't listen...
Apparently they not want to invest in quality at all....
Edits: 07/27/16
What a pitty that this transformers uses very thick EI laminations. Did they never heared of c-cores? What also is a disign failure is that they didnt use the winding space optimal, the Rdc could be a lot lower.
For your friend: more interleaving is not always the best solution http://www.turneraudio.com.au
While you may have a variety of opinions on transformer design, Electra-print do in fact make very good output transformers. I have compared them to a number of other popular makes and they consistently measure well and sound great in the same circuits.
Also, I have two EP transformers that differ only in that one has added on leads and the other has the windings coming out directly. The direct leads transformer measures the same with my limited equipment but sounds much better in the same circuit. Subjective opinion only, but it's repeatable and others can tell the difference as well.
Edits: 07/27/16
With all respect, how can you call this good for there very high prices?
They use M19 EI transformer laminations which is a non grain oriented steel (higher losses, high magnetizing force and lower exitation ). They didn't use the bobin optimally (extra high copper losses).Maybe the frequency response is good* (no info on there site) but at least two very important parameters are not good or even bad.
*but always less then when they used better cores.
Edits: 07/28/16 07/28/16
The EP Cu-wound transformers are solid all-round performers at a reasonable price. I have not heard their PSS or silver wound versions, but there are some really good winders of transformers at those price points and I'd probably be looking at them instead.
Just my opinion.
Regards,
91.
"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein
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.
---------------------------------------------------------------------------------
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.
-------------------------------------------------------------------------------------
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
What happened to parallel 12AWG runs of APEX Jr. wire?
I found some improvements with an 12AWG Apex Jr. ground buss in a SE 6V6 amp recently - subjectively more silent background.
Good. Different applications call for differing AWGs. 12 AWG in one place, 14, or maybe 16 AWG in another, although usually almost always try to do PARALLELED .
The entire audio chain needs to be wire optimized !!!
Jeff Medwin
Jeff,
The next mod is to remove the magnetic wire in the windings and optimize with a larger gauge wire?
Just thinking out loud.
.
.
.Thou shall not stand where I type for I carry a bottle of Certified Audiophile Air and a Pure Silver Whip.
But my point was a no-brainer pair of easy to do mods to improve the sonics of an existing, wound output. Something the original manufacturer overlooks consistently, likely till this day.
If you LOOK at the photos, the wire abound the bobbin does not fill up the bobbin. So, there is two large gaps internally on the top and bottom of the bobbin, between the bobbin and the iron core.
I would think this is sub-optimal from a design and material usage point of view.
Jeff
"The next mod is to remove the magnetic wire in the windings and optimize with a larger gauge wire?"
Sure, go ahead. But then you will find the wire bundle won't fit on the core sized for the laminations. So now you need to re-engineer the whole transformer. IOW, by that time you will be building an entirely new transformer.
And to do that the weekend tweaker is now faced with rather complex mathematics and physics to produce the results (specs) you desire. Don't just assume you can scale the size in a linear manner. And once you learn all that and have many years of experience - just as the original transformer winder does, you will no doubt find that the original design INCLUDING the leadout wires are in fact properly sized for the application.
So what's the point?
Hi, how did you put laminations back together with the same gap as before?
Thanks!
There is a piece of paper which determines the gap. EZ as pie.
Jeff Medwin
Are you sure that's a Welborne transformer? My transformer leads look very different and are much bigger solid core wire.
Palustris
The wiring mod as shown by Drlowmu is for the output transformer not the power transformer as you have shown.
The wiring mod pictured above is to a ElectraPrint 5 K to 8 ohm SE output transformer, gapped to do 100 mA. Notice, four lead wires total, two for 5 K primary and two for secondary, which I am guessing is 8 Ohms, 'have not measured it yet to know for sure.The double 16 AWG Mill Spec wire needs to go on ALL FOUR leads, to get the best improvement.
The referenced URL is my modification of a Hammond 274BX, a power transformer which is what I sometimes use to do two stage DC Type 45 SETs.
These mods are WONDERFUL, and it needs to be done throughout the audio chain, so there are no weak links.
An inch of bad wire can ruin the musical experience !! Imagine speaker lead outs of 22 AWG, off an output trannie !! Heck, imagine them IN and OUT, ugh, ... NO thinking in the implementation. Low fi to mid fi...... at best.
EZ to fix , do it thoughtfully !! Practice DILIGENTLY stripping insulation on the cut-off stock lead out wire, and you can execute graft, stock wire wrapped three times around, Wonder Soldered, even closer to the core !!!
Jeff Medwin
Edits: 07/18/16 07/18/16
That is NOT the power transformer. It is a 3K Electra-Print output transformer with multiple output impedance possibilities depending on how you arrange the various windings. There are provisions for 16r, 8r, 4r, and 2r.
.
Have Fun and Enjoy the Music
"Still Working the Problem"
I had output transformers from Electra Print once. Good bang for the bucks. "Sonically", What are the improvements?
Its the same type of improvements, giving you a automobile analogy, of taking a normally aspirated V-8 engine, with two double barrelled carbs, and feeding this very nice engine with
** a fuel line that is 1/8th of an inch in diameter ( 22 AWG from DHT anode) and
** using high resistance spark plug wires ( 22 AWG B+ lead in wire ). That is the EP Primary.
On the EP Secondary,
** its like running an exhaust system with a 1/2 inch diameter single exhaust pipe and
** powering the tires with a Yugo rear end ( two 22 AWG secondary wires).
How does it sound??
Depending upon how well your amp is executed ...every performance an audiophile and a music lover likes, is improved when these weak links are abolished. The better the amp's execution, the more the mods will bring to the table.
Jeff Medwin
What does Jack think about the mods?
Never asked him. His response may be predictable, one never knows. Who cares ??
More important is what I HEAR, and what "I" think, when I change things.
My added listening pleasure.
I've offered two no-brainer mods, tell me what you hear !!
Jeff
I concur with what Genp asked? Is there any sonic improvements after the mods?
Wouldn't the nylon bolts and nuts instead of the brass is better fitted for the application if minimizing magnetic flux shorting across the core is a concern? Just asking. And you know exactly when you are over torquing one of these nylon bolts.
.
.
.Thou shall not stand where I type for I carry a bottle of Certified Audiophile Air and a Pure Silver Whip.
Stainless steel bolts are much stronger than Brass or Nylon, and have no magnetic properties.
Some steel bolts can be magnetic. I used to think a better and higher grade "stainless steel" is non-magnetic but I changed my mind after reading this article.http://www.bssa.org.uk/topics.php?article=5
I am sure most "real" stainless steel would be non-magnetic but I am a little doubtful of the ebay ones from HK and China and some local hardware store.
Even when they are non-magnetic; they are still conductive.
I mostly skid steel and brass hardware on transformers whenever I can. Nylon and plstics bolts are quite strong for transformers and you won't screw up the lams and windings with over torqueing them. And they are excellent when you want to electrically isolate the transformers from the main chassis. I always try to isolate the OPT from the chassis ground in audio stuff.
.
.
.Thou shall not stand where I type for I carry a bottle of Certified Audiophile Air and a Pure Silver Whip.
Edits: 07/16/16
Post a Followup:
FAQ |
Post a Message! |
Forgot Password? |
|
||||||||||||||
|
This post is made possible by the generous support of people like you and our sponsors: