Re: WTB: ODS transformer set

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Re: WTB: ODS transformer set

Post by pompeiisneaks »

I'm curious about this myself, I'm going to build an ODS or SSS after I finish my wreck liverpool, what are the recommended brands? I've seen the docs and they seem to imply just standard fender parts numbers are fine, but I'm guessing that's the OS type, is there a current manufacturer out there that does a good job? Like mercury, heyboer, classictone, etc? Or any that fit the general specification?

I'm personally not yet convinced that transformers have some magic in them, and that so long as the transformer can handle the current given, and has the right voltages, it should be fine, but if someone has some compelling proof I could learn about, I'd love to see it :)

(xtian sorry to derail a bit but...)


EDIT: This was moved from this thread, as it derailed the actual request: http://ampgarage.com/forum/viewtopic.php?f=2&t=30135

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Re: WTB: ODS transformer set

Post by MakerDP »

pompeiisneaks wrote: Fri Apr 14, 2017 6:46 pm I'm personally not yet convinced that transformers have some magic in them, and that so long as the transformer can handle the current given, and has the right voltages, it should be fine, but if someone has some compelling proof I could learn about, I'd love to see it :)
~Phil
I totally agree with you as far as power transformers go. However, I do think there are plenty of sound samples out there that prove the output transformer can make a difference. But of course, with all things "guitar amp" the quality of each tone is totally subjective. It's all in the ear of the beholder. I don't think the bobbin material is where it's at, but the steel laminate type used and how it's wound (technique, tolerances, winding patterns, tightness, etc) are the determining factors.
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Re: RE: Re: WTB: ODS transformer set

Post by pompeiisneaks »

MakerDP wrote:
pompeiisneaks wrote: Fri Apr 14, 2017 6:46 pm I'm personally not yet convinced that transformers have some magic in them, and that so long as the transformer can handle the current given, and has the right voltages, it should be fine, but if someone has some compelling proof I could learn about, I'd love to see it :)
~Phil
I totally agree with you as far as power transformers go. However, I do think there are plenty of sound samples out there that prove the output transformer can make a difference. But of course, with all things "guitar amp" the quality of each tone is totally subjective. It's all in the ear of the beholder. I don't think the bobbin material is where it's at, but the steel laminate type used and how it's wound (technique, tolerances, winding patterns, tightness, etc) are the determining factors.
I wish I could remember where I read it, but some article or book excerpt was talking about how 99% of all audio amplifiers use almost identical core size, as the math for optimizing this is extremely complex, whereas older engineering books indicated a standard core size made perfect sense in this type of transformer. But I read this a while ago and don't recall all the details

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Re: WTB: ODS transformer set

Post by Krinkle »

[quote=pompeiisneaks post_id=371634 time=1492195566 user_id=16952]I'm personally not yet convinced that transformers have some magic in them, and that so long as the transformer can handle the current given, and has the right voltages, it should be fine, but if someone has some compelling proof I could learn about, I'd love to see it :)/quote]

I think it depends on the circuit and application. I don't have compelling proof (I'd have to swap PT's and get you to play them both) but I can tell you that I swapped out a Heyboer PT from Metroamp for a PT from Chris Merren in my 12000 Plexi build and I was blown away. I had always heard about OT's being critical to tone, but then I thought about it. It's not about handling the current, it's about the current able to be supplied, or to put it a better way, not being able to supply current, which is sag.

When you do the old all knobs on ten trick with a plexi, the PT sags when you play very aggressively with your right hand. The PT can't supply enough current and the voltage drops. A lower voltage means earlier clipping, meaning earlier distortion. Roll your guitar volume knob back (depending on the pickup of course) and play lighter, and you have that amazing dirty/crispy clean tone. As a matter of fact, pick dynamically and the amp will follow, if your amp is properly built/tuned.

My friend and I have the exact same build and had pretty much exact sounding amps and when I told him about it he was very skeptical. He came over and we A/B'ed them and he wasn't happy when he left. I told him it was just money.

In an ODS, it may not matter though, as the circuit and application are different from a Plexi from what I can see.
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Re: WTB: ODS transformer set

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pompeiisneaks wrote: Fri Apr 14, 2017 6:46 pm ".........that so long as the transformer can handle the current given"
This is where many get it wrong, the power supply is an integral part of the process. The key is duplicating the specs of the originals and many of the great amps had very poor power supplies from an engineering perspective.A great example is the Tweed Bassman, most of the power transformers used for modern builds are based around the BF models and some of these PT's have an HT rating at twice as much as what's found inside the originals. The end result is an amp that does not compress and respond like a period correct Tweed Bassman would, 470 -500 volts on the plates and stronger HT secondary is not a Tweed Bassman.

Plexi's.......the parts power transformers that was sold in one vendor's store and used in his kits had different specs that the PT's used in the amps with his nameplates on them......don't gave away the secret sauce.

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Re: WTB: ODS transformer set

Post by pompeiisneaks »

Okay, so now that's all some compelling evidence about the why. I now want to try some a/b comparisons. Logically it makes sense now too as they were cheap in the early fender days, trying everything to save a buck

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Re: WTB: ODS transformer set

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pompeiisneaks wrote: Wed Apr 19, 2017 2:26 pm Okay, so now that's all some compelling evidence about the why. I now want to try some a/b comparisons. Logically it makes sense now too as they were cheap in the early fender days, trying everything to save a buck
While Leo Fender was very frugal in ways and certainly cost was an issue, you have to think in the context of music at the time. In 2017 we have a solid 65 year history of electrical musical amplification evolution with entire cottage industries built around just electric guitars. In 1957, rock bands or even loud bands and playing to stadium sized crowds only 15 years later didn't even exist nor was even a concept.Thus, for the times Fender and other pioneers procured materials from what was available, the consumer electronics market and then of course as musicians needs evolved, the equipment evolved.


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Re: WTB: ODS transformer set

Post by JazzGuitarGimp »

Considering when the tweets were made, no one, including Leo, ever imagined guitarists driving amps into distortion. So no need for an over-speced PT.
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Transformer Technical Discussion

Post by pompeiisneaks »

I started a side topic on another thread that shoudl not have been there, I'm moving all posts related to it to this thread to clean that one up.

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Re: WTB: ODS transformer set

Post by ToneMerc »

JazzGuitarGimp wrote: Wed Apr 19, 2017 7:45 pm Considering when the tweets were made, no one, including Leo, ever imagined guitarists driving amps into distortion. So no need for an over-speced PT.
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Re: WTB: ODS transformer set

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Tone Merc, translate this if you don't mind: "470 -500 volts on the plates and stronger HT secondary is not a Tweed Bassman."

When I've worked on original '59 era Bassmans, 5F6-A, the voltages have been high on the plates. 495-503VDC (at 122VAC) seems a norm. The Fender schematics are not accurate here if that is your reference. The 6G6-A and 6G6-B may have used a different coded PT than the 59 Bassman (but identical to each other) with typically 495-503VDC on the plates. Here, looking at the Fender schematics, between the A & B it says 470VDC on one and 428VDC on the other - with the same tube compliment and the same PT. Impossible.

Anyway, all this aside, I used to think the PT was not that important. I should say that I thought, if the voltages were correct and the transformer functioned properly, it would do nothing to impact the tone and feel of the amp. But now I don't feel that way. I think the PT is very important. Also for reference, I would ask you all a question: Do you think a PT with a 7A filament supply would sound different than an identical one with a a 5A filament supply? I do.

And frankly, this is where I disagree with Ken in regards to the 7A supply that he seems to have decided on in the Express. Why did he do this? A Twin Reverb requires a 4.5A filament supply and a SR requires 4A. The TR has 10 tubes in it, the SR 8 (forget the rectifier for this example).

So, to break my thoughts down, recently I've come to believe that the filament supply, the windings themselves, actually generate a vibration that affects the core of the Secondary supply that in turn affects the sonics of the amp. ?? I think that there is a symbiotic relationship to the vibrations that the PT makes and the sound that arrives at the speaker, and further, if you could imagine an overriding frequency/hum that exists in an audio spectrum we can't necessarily hear, that that frequency/hum will impact the even the tone response of the amp circuit.

Haha, OK. That's my thought on this subject.
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Re: WTB: ODS transformer set

Post by ToneMerc »

rooster wrote: Fri May 26, 2017 8:36 pm Tone Merc, translate this if you don't mind: "470 -500 volts on the plates and stronger HT secondary is not a Tweed Bassman."

When I've worked on original '59 era Bassmans, 5F6-A, the voltages have been high on the plates. 495-503VDC (at 122VAC) seems a norm. The Fender schematics are not accurate here if that is your reference. The 6G6-A and 6G6-B may have used a different coded PT than the 59 Bassman (but identical to each other) with typically 495-503VDC on the plates. Here, looking at the Fender schematics, between the A & B it says 470VDC on one and 428VDC on the other - with the same tube compliment and the same PT. Impossible.

Anyway, all this aside, I used to think the PT was not that important. I should say that I thought, if the voltages were correct and the transformer functioned properly, it would do nothing to impact the tone and feel of the amp. But now I don't feel that way. I think the PT is very important. Also for reference, I would ask you all a question: Do you think a PT with a 7A filament supply would sound different than an identical one with a a 5A filament supply? I do.

And frankly, this is where I disagree with Ken in regards to the 7A supply that he seems to have decided on in the Express. Why did he do this? A Twin Reverb requires a 4.5A filament supply and a SR requires 4A. The TR has 10 tubes in it, the SR 8 (forget the rectifier for this example).

So, to break my thoughts down, recently I've come to believe that the filament supply, the windings themselves, actually generate a vibration that affects the core of the Secondary supply that in turn affects the sonics of the amp. ?? I think that there is a symbiotic relationship to the vibrations that the PT makes and the sound that arrives at the speaker, and further, if you could imagine an overriding frequency/hum that exists in an audio spectrum we can't necessarily hear, that that frequency/hum will impact the even the tone response of the amp circuit.

Haha, OK. That's my thought on this subject.
Rooster, it's simply in the context of modern mains voltages. I don't consider 122V /470V true vintages specs. Did the ones you worked on have the Triad or Schumacher power trannies. The Triad's are different from the Schu's. Also, I agree about filament loading, not sure though if it's vibration.

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Re: WTB: ODS transformer set

Post by TUBEDUDE »

Mains of 115V or so more likely in the late 50's, when I was a tyke.
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Re: WTB: ODS transformer set

Post by martin manning »

The voltages on Fender's original 5F6-A schematic show 117VAC line and 432V B+. Some of the Fender schematics have errors, but there is no reason to doubt these voltages. The '59 Bassman reissue schematic seems to be faithful to the original circuit but the voltages are all too high with 491 B+. The Limited shows a bit lower voltage at 476, using the same P/N for the power transformer and a vacuum rectifier... Still more than a 50's original running on modern line voltage. Why would Fender spec a PT that runs 45-60V higher than the original? It must come down to cost or a screw-up, which costs money to fix.
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Re: WTB: ODS transformer set

Post by rooster »

Martin, good question. What I can share is that the guy responsible for the redefined Strat body (getting back to the vintage body shape that was found on the early Fender 'Original Contour Body') reintroduced in '99 (or thereabouts) and also responsible for the Bassman RI, was a fellow named Ritchie Fliegler (formerly of Korg, then Marshall and ultimately being hired by Fender). He is on record as saying that both the new body shape and Bassman were copied from his personal '61 Strat and '59 Bassman. I'm sure there is no doubt they could have produced whatever they wanted in regards to the PT on the RI Bassman. They did (Fender) suggest that a 5U4, a GZ34, or a silicone rectifier plug could be used if the customer wanted to change the plate voltage. (But, oops, no bias pot was in the circuit!)

In regards to the original Tweed Bassman running a GZ34 (if 470VDC on a schematic can be believed), as Fender continued with the same PT (or same PT specs) as they moved to the 6G6, switching to silicone diodes could easily bring 500 VDC on the plates.
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