6.6k vs 8k Output Transformer Primary

Wrench66

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I'm planning a 5E3 build in the very near future and I am trying to nail down the output transformer. I was planning on using the classic tone 40-18090 output transformer. It has an 8k primary and a 4, 8, and 16 ohm secondary and is rated at 20 watts.

However, I have on hand a classic tone 40-18080 output transformer. It is substantially larger, 35 watts, and has a 4.6k and a 6.6k primary and a 4, 8, and 16 ohm secondary.

Could I use this OT for my 5E3 build?

The classic tone website describes the OT as: "This is a great multipurpose, 35W high fidelity, ultra linear, paper layer wound output transformer. The primary features both 4.3K Ohms and 6.6K Ohms. The secondary includes 4 / 8 /16 Ohm taps. It has a frequency response of 20-20 KHz. It comes with the aesthetically pleasing and classic looking fully enclosed, black powder coated end bell covers."

Thanks for your help.
 

ErictheRed

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So I'm not looking at a schematic diagram and even though a 5e3 is extremely common, I've never owned or messed around with one. But the 6.6k tap should be just fine, I would think.

On the other hand, do you really want a 35W high fidelity ultra linear transformer in a 5e3? That doesn't sound right to me offhand. What is the output transformer normally used in that circuit? I can't think of a Fender amp that uses an ultra linear transformer. I don't think you'll get any sag with that at all, and isn't sag a big part of the 5e3 sound?
 

Soul Tramp

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That's an ultra-linear transformer, not exactly what you'd build a 5E3 around. I'm sure it's intended for hifi use.
 

Wrench66

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Thanks for quick reply. I ordered the correct OT, 40-18090, but they sent a 40-18080. I know it isn't the correct OT, but wanted to make sure it wouldn't work before I went through the trouble of sending it back.
 

Wrench66

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So I'm not looking at a schematic diagram and even though a 5e3 is extremely common, I've never owned or messed around with one. But the 6.6k tap should be just fine, I would think.

On the other hand, do you really want a 35W high fidelity ultra linear transformer in a 5e3? That doesn't sound right to me offhand. What is the output transformer normally used in that circuit? I can't think of a Fender amp that uses an ultra linear transformer. I don't think you'll get any sag with that at all, and isn't sag a big part of the 5e3 sound?
The correct OT is the 40-18090, which is the one I ordered, but they sent the wrong one. I'm far from an expert in these things and was just curious if the one they sent would work.
 

ErictheRed

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It will "work," but you would probably find the amp very sterile. I'm not exactly sure what it would sound like, to be honest. You might install it as a science experiment, otherwise just return it.
 

Wrench66

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It will "work," but you would probably find the amp very sterile. I'm not exactly sure what it would sound like, to be honest. You might install it as a science experiment, otherwise just return it.
It would be interesting to see how it works, but I’m just going to return it. What’s hilarious is that the ot they sent is twice as expensive as the one I ordered.

What’s not hilarious is that I was hoping to have all the parts in hand and working on it by now. Instead, I’m sure the proper ot is a week from my door.
 

Wrench66

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I've contacted the vendor and they are sending the correct OT, so I will not be using the OT they sent. However, I would like to pick your guys brain a little more.

I've done a bunch of research online about this stuff and I think I could have made the OT they sent work. Since I am using a pair of 6V6 in push-pull, I need 8k of effective load resistance. So, I could use the 4.3k primary taps and the 4 ohm secondary taps to connect an 8 ohm speaker. The actual impedance at the 4 ohm tap would be 7.4 ohms, but I think that is close enough.

So my question is how would it sound? has anyone used an OT in this manner?

Like I said, I'm not looking to use the 35 watt OT in this build. The vendor has already sent me the return UPS label, but I want to have a better understanding of how all of this works.
 

ErictheRed

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It's hard to know how it would sound exactly if you don't just try it, and it's hard to describe sound with words, anyway. The issue is not the impedance, but rather the high power capability and ultra linearity. It doesn't seem like a transformer designed for a guitar amp. So I suspect that it would sound "sterile," for lack of a better word. You won't have any sag and you might find that the amp doesn't react to your playing like you would expect.

On the other hand, it might have a unique characteristic that you actually like. I don't know of an amp design that uses a transformer like that to compare it to (though there probably is one out there).

If it was me, I would wire it up as a science experiment, like I said. But then you may not be able to return it.
 
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Soul Tramp

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I don't know of an amp design that uses a transformer like that (though there probably is one out there).

Ultra-linear was/is used by Ampeg and Sunn for their bass amps. I build a 150W quad KT88 guitar amp that is ultra-linear. Note the size of the massive transformers!

r_DSC01912.jpg


r_DSC01914.jpg
 

ErictheRed

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Well okay, I don't know of a guitar amp that uses a transformer like that! Googling would probably find something, though.

With the right speakers (probably not typical guitar amp speakers), it might work well...
 
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grumphh

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Funny, i had always understood the term "ultralinear" in reference to guitar amp builds to be a particular way of wiring the power stage* - not an intrinsic property of a transformer?

EDIT: Just found out that the transformer apparently needs an extra tap in order to be able to be wired ultra linear :)

*And afa guitar amps are concerned actually "ultralinear" is, according to what i have read, not really a desirable way to wire them as they apparently lose a lot of the characteristic power stage breakup most guitar players seem to love.
 

Soul Tramp

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I designed this high-power 150W amp as a pedal platform for outdoor and large stage venues. The intent is to have a powerful amp that does not add coloration so all the tone shaping can be done with pedals. Think of a Twin Reverb on steroids.
 

Wrench66

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The ot had a 4.6k, a 6.6k, and ultra linear primary taps.

While I’m not trying to build a 5E3 clone, I want it to sound pretty close. I shipped it back today. Won’t get the proper one till next week
 

grumphh

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Now i am curious: To the best of my knowledge, the to large transformer with UL taps could have been used in the "traditional" way (non-UL) by simply isolating and not using the UL taps.

But what would using a far larger transformer than necessary do to the circuit/sound?
I mean, as long as the winding ratios are the same, it should perform the same as a smaller one.
Is it the primarys impedance/resistance that would somehow affect the performance? Or are other factors at work?

I'll freely admit to only having a rudimentary understanding of this - hence the question :)
 

Soul Tramp

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There are other factors. Core saturation contributes to the tone/voicing of an amp. It can be a good thing or a bad thing depending on your goals.
 

ErictheRed

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There is a very important factor called reactance, or magnetizing reactance. I've never sat and compared different transformers in the same circuit so I don't personally know how all of those factors would affect the sound. My experience here is in the realm of induction motor design, mostly.

I doubt very much that many other people on internet forums have ever rigorously compared transformers, unless you find someone working for a company that designs guitar amps. Designs, not just builds! Perhaps Soul Tramp here has. Most knowledgeable posters have probably at most tried 2-3 different but similar transformers and then decided on which one sounds best for their build.

So you could safely wire up that transformer, sure, and it would "work" fine. But I think that it's very hard for anyone to predict how it would affect the sound, outside of knowing that you wouldn't get any sag. You may get some more headroom in some designs, but I would guess not in a 5e3 circuit.
 
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The Ballzz

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There was recently a discussion, either here, at the Marshall forum, TDPRI or maybe even Strat Talk about why a Deluxe Reverb puts out 22 watts and a Princeton puts out 12 or 15 watts all with the same fixed bias power tubes and same rectifier. If I recall, a lot of that difference in wattage was due to to output transformer differences. I will provide a link, if I find it. I believe it was that same thread that included a brief description of the use of "Ultra Linear" design in some of the Silverface amp models. My take away was that the actual "ultra linear" amps required much more modification (maybe even transformer swaps) to get them to Blackface specs than did most other Silverface units.

While it is certainly enjoyable to cook and taste the sausage, it is also fun and enlightening to discuss "how" that sausage has been made! :h5:

Just My $.02,
Gene
 

Wrench66

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Now i am curious: To the best of my knowledge, the to large transformer with UL taps could have been used in the "traditional" way (non-UL) by simply isolating and not using the UL taps.

But what would using a far larger transformer than necessary do to the circuit/sound?
I mean, as long as the winding ratios are the same, it should perform the same as a smaller one.
Is it the primarys impedance/resistance that would somehow affect the performance? Or are other factors at work?

I'll freely admit to only having a rudimentary understanding of this - hence the question :)
That was exactly what I was asking originally! :)
 


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