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The Dynaco Tube Audio Forum

Dedicated to the restoration and preservation of all original Dynaco tube audio equipment - Customer support for Tubes4hifi VTA tube amp and preamp kits and all Dynakitparts.com products


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Bob Latino
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    Toroidal Versus EI Transformers

    deepee99
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    • Post n°1

    Toroidal Versus EI Transformers Empty Toroidal Versus EI Transformers

    Post by deepee99 Fri Sep 15, 2017 4:44 pm

    All other things being equal, including quality of wire, workmanship and physical isolation, which is better in terms of performance, stability, longevity and sound? Toroidal or EI Xformers? A lot of varying opinions flying around in the ether, I think it's a worthy discussion. Or are they application-specific: toroids for pre-amps and EIs for power amps. Inquiring minds want to know, and also to start a food-fight. Smile
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    corndog71
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    • Post n°2

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    Post by corndog71 Fri Sep 15, 2017 5:16 pm

    From what I've heard toroids are great as power transformers but not so good as output transformers or plate load transformers.
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    sKiZo
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    • Post n°3

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    Post by sKiZo Fri Sep 15, 2017 7:44 pm

    I've heard the same - also supposed to be more stable with less fluctuation and variation under load.

    My favorite toroidal ...

    Toroidal Versus EI Transformers Skizo-label
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    deepee99
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    • Post n°4

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    Post by deepee99 Fri Sep 15, 2017 7:56 pm

    A quadrophonic xformer? WOW! Is it made with unobtanium?
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    vtshopdog
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    • Post n°5

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    Post by vtshopdog Fri Sep 15, 2017 11:44 pm

    Skizo - you're making me pine for my beloved, long lost Sansui AU-919 ......
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    Bob Latino
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    • Post n°6

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    Post by Bob Latino Sat Sep 16, 2017 1:35 pm

    There is a discussion of toroids vs. EI type transformers at the link below. Yes - it's almost a 20 year old discussion but a lot of what is said is pretty accurate ..

    Soundtage magazine > torids vs. EI transformers

    My opinions > Toroids are fine for power transformers ... As OUTPUT transformers on tube amps > consider that McIntosh, Conrad Johnson, Audio Research, Rogue and other USA manufacturers of have never used toroids as output transformers on any of their tube amps .. Maybe they found that are harder to wind and/or more costly to wind ? Maybe they don't sound as good as a comparable EI transformer ? I can't really say ?

    Bob
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    j beede
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    • Post n°7

    Toroidal Versus EI Transformers Empty Re: Toroidal Versus EI Transformers

    Post by j beede Sat Sep 16, 2017 4:15 pm

    Toroids make fine output transformers. The issue is that a similarly specified EI or C transformer will have a larger core and will therefore operate at lower frequencies without saturating. Can a toroidal be wound onto a larger core? Yes it can. This results is a larger, more expensive transformer that is equivalent to an EI or C.
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    deepee99
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    • Post n°8

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    Post by deepee99 Sat Sep 16, 2017 5:03 pm

    Bob Latino wrote:There is a discussion of toroids vs. EI type transformers at the link below. Yes - it's almost a 20 year old discussion but a lot of what is said is pretty accurate ..

    Soundtage magazine > torids vs. EI transformers

    My opinions > Toroids are fine for power transformers ... As OUTPUT transformers on tube amps > consider that McIntosh, Conrad Johnson, Audio Research, Rogue and other USA manufacturers of have never used toroids as output transformers on any of their tube amps .. Maybe they found that are harder to wind and/or more costly to wind ? Maybe they don't sound as good as a comparable EI transformer ? I can't really say ?

    Bob

    Bob L., with all due respect, Mac, ARC, etc. are all owned by the same holding company. My guess is that they buy in bulk from the lowest bidder and they're no longer the companies of Gordon Gow, Roger Russell and Frank McIntosh era. From what I've seen of the latest Mac offerings are they were coronated by the bean-counters, not by engineers or sound junkies. Ergo, I don't see them as a useful reference point. VTA is the new reference point.
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    • Post n°9

    Toroidal Versus EI Transformers Empty Re: Toroidal Versus EI Transformers

    Post by Bob Latino Sat Sep 16, 2017 5:45 pm

    David,

    We can agree to disagree ...Almost nobody uses toroidal output transformers because they are more expensive to manufacture than EI output transformers. USA transformer companies like Edcor and Hammond do not make them. Read the 5th paragraph on Hammond's web site at the link below .. Hammond will not make toroidals "due to their inability to handle tube imbalance and high manufacturing cost."

    Hammond transformers

    There probably is a place for toroidal transformers in higher end specialty gear but not for the average Joe who wants good sound at a reasonable price ..

    Bob
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    deepee99
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    • Post n°10

    Toroidal Versus EI Transformers Empty Re: Toroidal Versus EI Transformers

    Post by deepee99 Sun Sep 17, 2017 12:26 pm

    deepee99 wrote:
    Bob Latino wrote:There is a discussion of toroids vs. EI type transformers at the link below. Yes - it's almost a 20 year old discussion but a lot of what is said is pretty accurate ..

    Soundtage magazine > torids vs. EI transformers

    My opinions > Toroids are fine for power transformers ... As OUTPUT transformers on tube amps > consider that McIntosh, Conrad Johnson, Audio Research, Rogue and other USA manufacturers of have never used toroids as output transformers on any of their tube amps .. Maybe they found that are harder to wind and/or more costly to wind ? Maybe they don't sound as good as a comparable EI transformer ? I can't really say ?

    Bob

    Bob L., with all due respect, Mac, ARC, etc. are all owned by the same holding company. My guess is that they buy in bulk from the lowest bidder and they're no longer the companies of Gordon Gow, Roger Russell and Frank McIntosh era. From what I've seen of the latest Mac offerings are they were coronated by the bean-counters, not by engineers or sound junkies. Ergo, I don't see them as a useful reference point. VTA is the new reference point.

    A bit of esoterica in that Soundstage article: the DC offset issue that jams up toroids. You can create your own DC offset if the two sides of your circuit-breaker panel aren't reasonably load-balanced. This is where I yield to professional electricians. But if you're pulling all the 20-amp breakers off one side and just a few 15-amp breakers for 15 amps on the other side, you've likely got an offset issue in the making. And it ain't safe, either.


    Last edited by deepee99 on Mon Sep 18, 2017 1:07 pm; edited 1 time in total (Reason for editing : clarification)
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    • Post n°11

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    Post by fp2000 Tue Sep 19, 2017 2:16 pm

    Since we are on this topic of transformers. I am planning to build a vta st-70 type amp with a custom chassis. I still need to source the transformers (most limely from Bob
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    • Post n°12

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    Post by fp2000 Tue Sep 19, 2017 2:37 pm

    the question was. Are there any disadvantages from mounting the power transformer vertically?
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    • Post n°13

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    Post by Bob Latino Tue Sep 19, 2017 3:00 pm

    fp2000 wrote:Since we are on this topic of transformers. I am planning to build a vta st-70 type amp with a custom chassis. I still need to source the transformers (most limely from Bob

    fp2000 wrote:the question was. Are there any disadvantages from mounting the power transformer vertically?

    I do not sell any of the VTA amp's transformers separately outside the kits. Check with Dynakitparts for a set of ST-70 type transformers.

    However you mount the three transformers, make sure that the plates of the power and the output transformers do not run in the same direction. On a stock Dynaco ST-70 the plates run horizontally on the POWER transformer and vertically on the OUTPUT transformers. This will minimize any type of interaction between the power and output transformers because the magnetic fields are in opposing directions.

    Bob
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    • Post n°14

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    Post by Peter W. Tue Sep 19, 2017 3:14 pm

    I believe that McIntosh still winds their own transformers in-house.

    At the same time, and given that they have been doing so for a *VERY* long time, the machinery is entirely paid-for, the R&D negligible, and the process very well understood. There would be no reason at all for them to experiment with toroids for any purpose whatsoever.

    Note also: Best Buy is now selling McIntosh along with a number of other 'high-end' brands. Interesting.

    Poll: Anyone here actually LIKE green LEDs shining up the fundaments of their small-signal tubes? I do not.
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    • Post n°15

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    Post by deepee99 Tue Sep 19, 2017 3:21 pm

    Peter W. wrote:I believe that McIntosh still winds their own transformers in-house.

    At the same time, and given that they have been doing so for a *VERY* long time, the machinery is entirely paid-for, the R&D negligible, and the process very well understood. There would be no reason at all for them to experiment with toroids for any purpose whatsoever.

    Note also: Best Buy is now selling McIntosh along with a number of other 'high-end' brands. Interesting.

    Poll: Anyone here actually LIKE green LEDs shining up the fundaments of their small-signal tubes? I do not.
    I vote "Nay." Catchy show-room eye-candy, one supposes. Serves no other purpose.
    Best Buy? Good Lord. I recall back in the "fair-trade" days when each Mac dealer had to be individually certified by one of Gordon Gow's tekkies, and could not sell below list price. The old Mac clinics were great, too. You could bring in a rat's nest of an old McIntosh amp and they would restore and bring it back up to spec right on the spot. Ah, the McIntosh of yesterday (sigh)
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    Post by fp2000 Tue Sep 19, 2017 4:24 pm

    thanks Bob
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    • Post n°17

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    Post by Tubes4ever Fri Sep 22, 2017 4:25 pm

    Peter W. wrote:I believe that McIntosh still winds their own transformers in-house.

    At the same time, and given that they have been doing so for a *VERY* long time, the machinery is entirely paid-for, the R&D negligible, and the process very well understood. There would be no reason at all for them to experiment with toroids for any purpose whatsoever.

    Note also: Best Buy is now selling McIntosh along with a number of other 'high-end' brands. Interesting.

    Poll: Anyone here actually LIKE green LEDs shining up the fundaments of their small-signal tubes? I do not.

    Absolutely not. The only glow I like is heater glow.
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