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Guest

Mon Dec 24, 2018 4:45 pm   



On Monday, 24 December 2018 12:46:10 UTC, Tauno Voipio wrote:

Quote:
Some time ago the OP posted a transistor amplifier with two
emitter followers in push-pull and the autotransformer as
the emitter feed choke. The speaker load was to be connected
between the emitters. The expected frequency range is simply
not realizable with audio transformers. Five decades is a
heavy challenge even with RF transmission line and magnetics
transformers.

I just do not understand him wanting all the troubles of the
transformer, as there is no such pressing need for it as in
tube amplifiers. But more than 50 years in professional electronics
has not given me an understanding of the audio things ...


Maybe splitting the frequency range over 2 transformers is possible. Though I'm not clear why this arrangement.


NT


Guest

Tue Dec 25, 2018 2:45 am   



>"Some time ago the OP posted a transistor amplifier with two
emitter followers in push-pull and the autotransformer as
the emitter feed choke. The speaker load was to be connected
between the emitters. "

You are correct. My design skills were not as good back then and if you remember those outputs were biased from the CT of the driver transformer.

I am eliminating that transformer and the problem I had back then is I was not confident enough to to it. I am now.

Quote:
"The expected frequency range is simply
not realizable with audio transformers."


Bullshit, I had a pair of amps built by my Uncle (had been RADAR Man in USAF) using Chicago Transformer BO-15s (rare as hell) as the out put iron. I am talking FULL Williamson, with the cathode winding. It reproduced turntable infrasonic rumble. The cones moved as if they were backed by lead acid batteries.


>"Five decades is a heavy challenge even with RF transmission line and magnetics transformers."

Yes but it has been done. My project should be simpler because I do not wan a high impedance primary. Just the secondary, or a one to one.

>"I just do not understand him wanting all the troubles of the
transformer, as there is no such pressing need for it as in
tube amplifiers. But more than 50 years in professional electronics"

The part apparently you do not understand is that I am after a certain sound which people with fifty fucking grand turntable will buy. We are not talking about a buck a watt there. The lowest powered one maybe 60WPC will be about four grand or whatever. This is not going to be at Bestbuy.

>"has not given me an understanding of the audio things ... "

A murky field to say the least,l but I am starting to feel my way through it. All I need is two prototypes, with approved credit they will be shipped all over the world for people to audition. People in that realm do such things. Send each other amps n shit.

But I want mine to be exceptional. I mean truly above and beyond. The circuitry, everything. I'll make it public. Fuck a patent, MY people will want it built by ME.

My want for transformers is because of certain reasons. I GOT transformers I can use right now. But any metrics derived from that incarnation of the unit will be useless when the real transformers get here. I can't count on that.

Of course I can use what I got for test, and there is a hell of alot of work to do. If I drop everything I might have the design done by 2020. You wanna try ? Go right ahead but it will be chopped off at the neck thousands of times because it is not to my specs.

The idea here is to produce the cleanest tube-like sound with all its trimming without the transistor sound. If the tone is in the bypass mode, and if soft clipping or clip proof is invoked you are not to the level of actually invoking it, the sound is all tubes until it hits the JFET at the input of the real power amp.

Non=clip, soft clip, tone controls (not loudness, which I will get into why mine is better) as long as the are not invoked, they stay out of the audio path and 12AU7s do the job.

Then I need a low speed silent fan to keep that heat off my transistors.

More later.

I detect a market and have access to it/them. I CAN do this, therefore I shall. In for a buck, in for a bullet.

Tim Williams
Guest

Tue Dec 25, 2018 11:45 am   



<jurb6006_at_gmail.com> wrote in message
news:e6ec3759-fdbd-4eb7-9c0e-4dd95f7d3507_at_googlegroups.com...
>>"Some time ago the OP posted a transistor amplifier with two
emitter followers in push-pull and the autotransformer as
the emitter feed choke. The speaker load was to be connected
between the emitters. "
Quote:

You are correct. My design skills were not as good back then and if you
remember those outputs were biased from the CT of the driver transformer.


Well hell, emitter followers, tubes wish they could have an output impedance
so low -- even in class AB, neither transistor is really let go of
controlling that load. As long as you're driving the bases with
complementary signals and no weird predistortion business (which would only
make things worse, anyway), the transformer really doesn't matter.

Get a 120/240V 50Hz toroid, probably uh, 500VA or so. More is better. If
it's isolation (120:120V), wire it together in CT. If it's just whatever
primary, hook the two halves together in CT and ignore the secondary.

You won't know the difference. I guarantee it. Full money back, pending
double blind testing, offer expires non transferrable etc etc...

Honestly I'd be more worried that you're going to blow your spec (such that
it is) on output impedance alone. Even a fairly high gNFB tube amp does
worse than an emitter follower with none. Zo is the dominant part of tube
sound.

Tim

--
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Design
Website: https://www.seventransistorlabs.com/

Tauno Voipio
Guest

Tue Dec 25, 2018 4:45 pm   



On 25.12.18 11:57, Tim Williams wrote:
Quote:
jurb6006_at_gmail.com> wrote in message
news:e6ec3759-fdbd-4eb7-9c0e-4dd95f7d3507_at_googlegroups.com...
"Some time ago the OP posted a transistor amplifier with two
emitter followers in push-pull and the autotransformer as
the emitter feed choke. The speaker load was to be connected
between the emitters. "

You are correct. My design skills were not as good back then and if
you remember those outputs were biased from the CT of the driver
transformer.


Well hell, emitter followers, tubes wish they could have an output
impedance so low -- even in class AB, neither transistor is really let
go of controlling that load.  As long as you're driving the bases with
complementary signals and no weird predistortion business (which would
only make things worse, anyway), the transformer really doesn't matter.

Get a 120/240V 50Hz toroid, probably uh, 500VA or so.  More is better.
If it's isolation (120:120V), wire it together in CT.  If it's just
whatever primary, hook the two halves together in CT and ignore the
secondary.

You won't know the difference.  I guarantee it.  Full money back,
pending double blind testing, offer expires non transferrable etc etc...

Honestly I'd be more worried that you're going to blow your spec (such
that it is) on output impedance alone.  Even a fairly high gNFB tube amp
does worse than an emitter follower with none.  Zo is the dominant part
of tube sound.

Tim


There is one point the OP may not be thought about: The emitter
followers need bipolar drive, so he has to provide a negative
supply out of the originally intended unipolar car voltage supply.

He'd better off with a DC-coupled H-bridge and a suitable diode
function generator to bring the tube 3/2-power distortion.
The DC coupling will get rid of the lower frequency limit, but
it brings along possible problems with DC offsets.

--

-TV

Tim Williams
Guest

Wed Dec 26, 2018 1:45 pm   



"Tauno Voipio" <tauno.voipio_at_notused.fi.invalid> wrote in message
news:pvtgjj$lud$1_at_dont-email.me...
Quote:
There is one point the OP may not be thought about: The emitter
followers need bipolar drive, so he has to provide a negative
supply out of the originally intended unipolar car voltage supply.

He'd better off with a DC-coupled H-bridge and a suitable diode
function generator to bring the tube 3/2-power distortion.
The DC coupling will get rid of the lower frequency limit, but
it brings along possible problems with DC offsets.


I'm assuming it's going to be an old-fashioned "resistance coupled"
interstage, so the negative voltage comes for free as long as you aren't
expecting it down to 0Hz. But, as I've said many times in this thread --
who knows.

Tim

--
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Design
Website: https://www.seventransistorlabs.com/


Guest

Tue Jan 01, 2019 12:45 pm   



Sorry to top post but this is the only way.

I will post up the design. It doesn't matter. If I even get a provisional on it,l that gives the Chinese, the Japanese, and whoever else-ese the design. If I sell two of them, them people will make sure to have one at least.

My thing now is fuck it,l you think you can build it better - DO IT. I think people will buy mine for a couple of reasons,l and I will of course tout them in the ads.

Fuck a patent, copying me is better flattery than any money could buy.

Soon.

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