A friend gave me an amp out of a Baldwin organ a few days ago. While looking up schematics for different types of EL84 amps I discovered something interesting but I don't know the reason for it. The organ transformers are both (single pair for the auxilary amp & dual pairs of EL84s for the power amp) PP non-linear and almost ever schematic I've found for a hifi or guitar amp that uses these tubes shows linear transformers.
Why would the organ not use a linear transformer with these tubes and other amps do?
I can't find any Baldwin schematics that use this tube but I have seen others on ebay and found out it's a 54A.
EL84 transformers
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gui_tarzan
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EL84 transformers
--Jim
"He's like a new set of strings, he just needs to be stretched a bit."
"He's like a new set of strings, he just needs to be stretched a bit."
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Stevem
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Re: EL84 transformers
I do not understand what you are stating in your post here, if you mean that the aux amp(s) run one output tube which must be single ended and the main amp runs two outputs in pp, than yes organ amps of many manufactures do that a lot!!
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Re: EL84 transformers
I'm not clear what you are saying. Did you say there are a total of 6 transformers:
Aux: PT + SE OT?
Main 1: PT + PP OT?
Main 2: PT + PP OT?
What do you mean by non-linear and what leads you to this statement?
Aux: PT + SE OT?
Main 1: PT + PP OT?
Main 2: PT + PP OT?
What do you mean by non-linear and what leads you to this statement?
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martin manning
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Re: EL84 transformers
Maybe Jim meant to say the OT's are not ultra linear types?
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martin manning
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Re: EL84 transformers
Yes, I've understood "not-UL" as martin did.
But... who knows...
But... who knows...
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gui_tarzan
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Re: EL84 transformers
There are two amps on this chassis. One uses a quad of EL84, the other uses a pair. Both are PP circuits and transformers, but they have the standard, non-linear blue/red/brown primary wires. They don't have the extra pair of leads like my Traynor amp transformers have.
It's more or less a philosophical question - why run linear vs non-linear on a guitar amp?
It's more or less a philosophical question - why run linear vs non-linear on a guitar amp?
--Jim
"He's like a new set of strings, he just needs to be stretched a bit."
"He's like a new set of strings, he just needs to be stretched a bit."
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martin manning
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Re: EL84 transformers
It's the use of the term "non-linear" that is throwing people off. What you mean to say is these power amps are non-UL (or non-distributed load) configurations. Nothing says they have to be... for examples of guitar amps that use EL84's without DL OT's, how about Marshall 18W or Vox AC30? The argument against DL usually runs along the lines of it sounds too Hi-Fi for a guitar amp.
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gui_tarzan
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Re: EL84 transformers
Ok, that's fair. By "non" linear I'm referring to the three-lead primary since most people refer to the five-lead as an ultra-linear transformer. Probably not the correct terminology but it's how I separate them in my mind.
--Jim
"He's like a new set of strings, he just needs to be stretched a bit."
"He's like a new set of strings, he just needs to be stretched a bit."
Re: EL84 transformers
So, I think you've got a real score on your hands. Lots of promising iron -- enough to build 3 amps!
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Stevem
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Re: EL84 transformers
On a UL type OT the extra two leads are on the secondary winding, not the primary!
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
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martin manning
- Posts: 14308
- Joined: Sun Jul 06, 2008 12:43 am
- Location: 39°06' N 84°30' W
Re: EL84 transformers
Steve, you need more coffee!Stevem wrote:On a UL type OT the extra two leads are on the secondary winding, not the primary!
Re: EL84 transformers
??? They are on the primary. You need to connect screens to them.
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gui_tarzan
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Re: EL84 transformers
Did someone hack your account Steve? 
--Jim
"He's like a new set of strings, he just needs to be stretched a bit."
"He's like a new set of strings, he just needs to be stretched a bit."
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gui_tarzan
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- Joined: Thu Jan 16, 2014 3:10 am
- Location: The 26th State
Re: EL84 transformers
Ok, so the Vox AC30 power amp uses a 50 ohm resistor on the cathodes, is that really enough?
--Jim
"He's like a new set of strings, he just needs to be stretched a bit."
"He's like a new set of strings, he just needs to be stretched a bit."