Full coil 16 ohm vs 8 ohm partial coil - matching speaker

[Helmholtz]

I think that his point, that the difference between 8 and 16 ohm versions of the same speaker model are likely to be rather more significant than differences between the 8 and 16 ohm OT taps of any given transformer, is valid.

Not sure.
The measurements of Martin Manning do show significant difference, e.g. 3dB at 10kHz (probably more with a higher source resistance).
I don't agree that frequencies above 5kHz don't matter with a guitar speaker, as that's where most of the "chime" happens.

[didit]

Hello --

Opening apology to Phil D for adding another somewhat off-topic note into his thread. It'll be my last.
-----

[...]
There is no "mystique/mojo/voodoo hoodoo" about them.

No one invoked anything relating to "tone" mystique until your post. Nor was anyone disagreeable, with the obvious exceptional.

No claims on output transformers having "flat" or even linear transfer -- just that application of sound R&D can make relative positive improvements in audio output transformers, and those improvements have no utility and certainly zero if not negative value for a narrow band transformer application. For fun and enlightenment, read up on the excellent example captured and key within this patent:

https://patents.google.com/patent/US4321553A

Steel mass is but one of several contributing ingredients to transformer engineering. Having designed SMPSs I'd agree transformers are certainly smaller, though size and weight for that sub-element is just one beneficial aspect of the "whole premise".

Regards ..

[flemingmras]

Hello --

Opening apology to Phil D for adding another somewhat off-topic note into his thread. It'll be my last.
-----

[...]
There is no "mystique/mojo/voodoo hoodoo" about them.

No one invoked anything relating to "tone" mystique until your post. Nor was anyone disagreeable, with the obvious exceptional.

No claims on output transformers having "flat" or even linear transfer -- just that application of sound R&D can make relative positive improvements in audio output transformers, and those improvements have no utility and certainly zero if not negative value for a narrow band transformer application. For fun and enlightenment, read up on the excellent example captured and key within this patent:

https://patents.google.com/patent/US4321553A

Steel mass is but one of several contributing ingredients to transformer engineering. Having designed SMPSs I'd agree transformers are certainly smaller, though size and weight for that sub-element is just one beneficial aspect of the "whole premise".

Regards ..

In light of this thread, and just to get an answer from an actual transformer manufacturer to either (a) prove a point, or (b) maybe grab knowledge I didn't have previously, I took the liberty to email my rep at Heyboer Transformer -

When it comes to tube amp transformers, are there really any differences at all in the construction of an output transformer vs a power transformer? I mean…either one can be wound in a plastic bobbin or paper interleave, and the core dimensions are usually different (not by much on some really), but they’re all wound the same, use the same type of magnet wire, same core steel plates, and operate identically correct? Like the magnet wire sizes are different and they may be constructed for different ratios, voltage and current handling, but otherwise the same? Or am I thinking wrong?

The response I got was " You got it figured out, that is the basics of it."

While there may be different design considerations for each application, once we get down to the core theory of operation, output transformers are really just power transformers for speakers. That's not an oversimplification.

I implicated the "tone mystique" to shut down any potential cork sniffery that this thread may bring about.

[pjd3]

Tell ya what,

I'm fortunate to work as an R&D electronic tech at one of the biggest manufacturers of medical Defib/monitors and ventilators in the world, and I"m pretty friendly with the principal systems engineer who is the engineer that all other engineers report to. Hes a "fart smeller" and finds my interest in tube amps humorously admirable. He has been big in audio, designing 4-way towers and crossovers, and spend some years as the main transformer designer at some company; He knows alot about transformers and about audio and always welcomes my questions about these things (unless he's busy which is quite often).

I will describe the tenets of this thread and see what he knows about any varying design and configuration of transformers, particularly output transformers and see what he knows about potential differences that could produce differences in sonic presentation. I'm sure there are plenty of measurable variances but, we are probably mostly concerned with what we might hear.

I'll bring that back here sometime this coming week when I see him. He's been absolutely great at priming me on how to test transformers for leakage inductance and a few other characteristics, and I've done some of them using the expensive LCR bridge that we have in work - shorting various taps and primary and taking measurments. It was all very interesting to me.

Best,
\PHil D.

[TUBEDUDE]

Must be Zoll...unless Physio-Control makes vent now.

[sluckey]

I implicated the "tone mystique" to shut down any potential cork sniffery that this thread may bring about.

You seem to be quite knowledgeable and that's good. But your arrogance and quickness to belittle others is just gonna make you very unpopular in the garage. Hopefully you will find a "smart" crowd to hang with.

[didit]

Despite prior pledge of a "last", there's enough directional shift that calls for least one more.

I will describe the tenets of this thread and see what he knows about any varying design and configuration of transformers, particularly output transformers and see what he knows about potential differences that could produce differences in sonic presentation. I'm sure there are plenty of measurable variances but, we are probably mostly concerned with what we might hear.

I'd reinforce an observation Dynaco's output transformer line (along with Peerless et al) as representative for how superior wide band designs differ from narrow band 50-60Hz power transformers.

..

[flemingmras]

I'd reinforce an observation Dynaco's output transformer line (along with Peerless et al) as representative for how superior wide band designs differ from narrow band 50-60Hz power transformers.

..

You make a bold assumption that power transformers are "narrow band".

Transformers have a minimum frequency that they will operate down to without saturating. They don't just say "Oh! 61/80/100/250Hz" or "Oh! 49/30/20Hz" and then tank. For most tube amp power transformers, 50Hz is the minimum frequency they will transform at without saturating. If they were wound with the proper ratios and magnet wire, they'd work fine as output transformers...because they're literally the same thing.

Output transformers are just power transformers for speakers. Your typical push-pull output section is just a full wave center tapped rectifier circuit flipped upside down and backwards. The tubes modulate DC from the power supply back into AC through the output transformer primary, which ends up transformed down to a much lower voltage on larger wire for higher current. Your guitar pickup signal is literally running a DC to AC pump that's pumping DC back into AC through that transformer. If you had a 60Hz sine wave generator on the input and the transformer had a 120V secondary tap, you could easily run a 120VAC light bulb at full brightness right off the output.

[flemingmras]

You seem to be quite knowledgeable and that's good. But your arrogance and quickness to belittle others is just gonna make you very unpopular in the garage. Hopefully you will find a "smart" crowd to hang with.

I'd be name calling if I were belittling others. Not sure where you're getting "arrogance" from. I'm simply shooting down myths and misinformation that continues to run rampant in these circles here 25+ years after it was created. Much of it by the School of Aspen Pittman. Many of these people who read this garbage are so committed to what they read that they refuse to believe anything to the contrary just because they like the person who wrote it that much.

Nothing in this industry seems to have changed. It's not about what you know, or even who you know, or how solid your product is. It's about how many people like you, and that's a dangerous business model.

[Helmholtz]

A PT typically has a narrower bandwidth than an OT. Many years ago I measured a few for frequency response. A PT might have a bandwidth <5kHz, while a good OT can have a bandwidth >20kHz.
Lower limit is mostly determined by Lpri/Raa and the upper limit depends on leakage inductance and winding capacitance, which both can be lowered by construction/winding pattern.
Saturation is something else. It depends on V/f (more exactly on the voltage-time area), significantly lowers inductance and causes distortion.
PTs are often operated close to saturation for cost reasons.

[flemingmras]

A PT typically has a narrower bandwidth than an OT. Many years ago I measured a few for frequency response. A PT might have a bandwidth <5kHz, while a good OT can have a bandwidth >20kHz.
Lower limit is mostly determined by Lpri/Raa and the upper limit depends on leakage inductance and winding capacitance, which both can be lowered by construction/winding pattern.
Saturation is something else. It depends on V/f (more exactly on the voltage-time area), significantly lowers inductance and causes distortion.
PTs are often operated close to saturation for cost reasons.

Yes, but certainly not 50-60Hz narrow, and that doesn't mean it doesn't work identically in regards to operating principles.

People like to find just one small difference and all of a sudden "Oh...it's completely different".

[pjd3]

Yeah, I do find you a bit arrogant flemingras, not that that is the worst thing to be - you can know alot and be arrogant, you can be generous and be arrogant, you might even be able to be a decent father and husband and be a be arrogant. Proving your own correctness is a great way to mask arrogance, "See, I'm right about this? How can it be arrogant if I"m correct?" which I'm getting that from you in hordes.

You've given me alot to think about, more than I could have anticipated, but in your quest to "straighten everyone out", you pretty much highjacked the original tenets of my original post, which was to hear from someone that actually did the work of A/B testing the "8 ohm to matching tap, 16 ohms to matching tap".
For whatever the technical reason is that makes for any perceivable differences (if it is perceivable to the person involved), its likely to come down to the aesthetic preference of one person to the next. After all, we tend to make our final judgement of what we like, not on technical grounds but on "Does it sounds good?" grounds. And thats OK, regardless of what is causing the technical elements that drive the difference.

You have alot of very interesting thoughts and facts to share and I know I would learn alot from you. I just hope you don't end up ruining that, that would kinda suck.


Sincerely yours,
Phil D

[pdf64]

the original tenets of my original post ... was to hear from someone that actually did the work of A/B testing the "8 ohm to matching tap, 16 ohms to matching tap".

Even if someone has done such a comparison, I'm sceptical that it would prove anything about the respective tonality attributable to different points on the OT secondary winding -

... the difference between 8 and 16 ohm versions of the same speaker model are likely to be rather more significant than differences between the 8 and 16 ohm OT taps of any given transformer ...

[flemingmras]

Yeah, I do find you a bit arrogant flemingras, not that that is the worst thing to be - you can know alot and be arrogant, you can be generous and be arrogant, you might even be able to be a decent father and husband and be a be arrogant. Proving your own correctness is a great way to mask arrogance, "See, I'm right about this? How can it be arrogant if I"m correct?" which I'm getting that from you in hordes.

You've given me alot to think about, more than I could have anticipated, but in your quest to "straighten everyone out", you pretty much highjacked the original tenets of my original post, which was to hear from someone that actually did the work of A/B testing the "8 ohm to matching tap, 16 ohms to matching tap".
For whatever the technical reason is that makes for any perceivable differences (if it is perceivable to the person involved), its likely to come down to the aesthetic preference of one person to the next. After all, we tend to make our final judgement of what we like, not on technical grounds but on "Does it sounds good?" grounds. And thats OK, regardless of what is causing the technical elements that drive the difference.

You have alot of very interesting thoughts and facts to share and I know I would learn alot from you. I just hope you don't end up ruining that, that would kinda suck.


Sincerely yours,
Phil D

Honestly, it all comes down to the hills that many of you are willing to die on.

The guitar world is full of non-tech types rife with confirmation bias. They take anecdotal evidence at face value because they don't know any better, then latch on to anyone else high up in the industry who appears to "confirm" their anecdotal evidence.

Then, when the guys who actually know a thing or two step in to dispel the misinformation, and perhaps explain why your anecdotal evidence presents as you see it, but explains why it is not as you interpret it, it becomes "shoot the messenger" style credential wars.

"Oh...well...<INSERT FAVORITE "GURU" HERE> has worked on amps for <INSERT FAVORITE CELEBRITY GUITARIST HERE>. What celebrity guitarists have YOU done work for?"

That is called "argument from authority", or "appeal to authority" logical fallacy. It's a mental shortcut to prevent having to explain their "evidence" themselves by appealing to testimony from someone higher up in the chain (because they truly don't understand it themselves).

My argument is either good or it's bad. Citing to credentials is a horrible way of making an argument.

I'm actually shocked (and perhaps not at the same time) that much of this misinformation seems to have survived as long as it has. So after many years of doing this and still seeing the same crap floating around, it gets a little irritating. Like "Why are we still talking about this nonsense? This has been debunked with empirical data and non-disputable evidence 100,000 times over."

It begins to feel as if you're not listening either because (a) you don't understand it, or (b) it's not what you want to believe because it doesn't sound as cool, or (c) they just don't like you.

This is why we use the term "corksniffer". Sniffing the cork tells you literally nothing about the wine in the bottle, but they'll keep right on sniffing the cork swearing that it does.

The "does it sound good" is a dangerous territory to be in. Just because something is user adjustable does not mean it is a "tone tweak". Some things are adjustable as a means of keeping the amp operating within its designed operating limits regardless of load impedance, whose brand of tubes you have in it, wall voltage, etc. Output impedance is selectable solely to match the amp to the load. Bias is adjustable solely to set the amp into its spec'd operating class within safe limits. 70% plate dissipation is a maximum limit, not a "must be set here to sound its best" ("more" != "better"...the classic "If you're not biased at 70% then you're not using the amp to its fullest potential" fallacy). For your tone to be magically "corrected" by altering a critical electrical property means that your amp is not voiced to your liking, which comes down to the preamp circuit design/topology, voltages, component values, etc.

Lastly...no one buys speakers for tone based on impedance. Speaker impedance is based on speaker configuration and intended use. If you want a 2x12 16 ohm cab, you use two 8 ohm speakers in series (the drawback being open load condition if one should fail), or if you want an 8 ohm 2x12 cab, you use two 16 ohm speakers in parallel. If you want a 4x12 16 ohm cab, you use four 16 ohm speakers in series parallel. Four 4 ohm speakers will also work, but then you end up with an open load condition if one fails. 16 ohm is an ideal impedance for speaker cabs as it maximizes the number of cabs you can connect to the same amplifier. But for one to say "I like how my amp sounds at "X" ohms"...if you're having to tweak the impedance at all to get the right sound, you either have the wrong speakers or your amp just isn't voiced properly.

[flemingmras]

Even if someone has done such a comparison, I'm sceptical that it would prove anything about the respective tonality attributable to different points on the OT secondary winding -

This right here. You have a reciprocating motor wound with different coil wire, different inductance, different electrical properties overall. Too many variables in play to make a valid determination when one property may offset the effects of another to say with any amount of conclusivity that it's because you're using a different tap, or because you're using the whole secondary vs 70.7% vs 50% of the secondary. All bets are off with mismatching impedance as well (which you shouldn't be doing anyway if you want the tubes/transformers to live any reasonable length of time). Results from any sort of resistive load analysis will be invalid as it relates to driving an inductive load, such as a reciprocating motor.