PT vs OT difference

ce24 · March 3rd, 2008, 02:13 PM

Well I've got the amp build bug and I have come across a number of old amplifiers of various types that I can scavenge what looks tobe some real nice transformers and lots of other parts. I've been looking at different sites and haven't been able to find some designation of how to tell them apart...They look the same in their different styles. any web sites to look at for info. plus what wires do what?

Thanks
ce24

OK PT multiple taps
OT has three wires coming out of it.

tazzboy · March 3rd, 2008, 05:08 PM

PT = Power Transformer
OT = Output Transformer

ce24 · March 3rd, 2008, 05:23 PM

I wasn't very clear was I? I know OT and PT, if they aren't stamped is it just the number of wires that tell you which one it is?

Thanks

CE24

4 Strings · March 3rd, 2008, 05:24 PM

"I have come across a number of old amplifiers of various types that I can scavenge"

Sounds interesting, TELL US MORE!

I may over simplify a bit, but along with some other guys' tips this may help you:

The OT has two of its leads - its secondaries - attached to the speaker jacks (or at last one of them, one may be grounded to the transformer Tweed Deluxe OT style, in which case only one of the leads go to the speaker output).

The PT on the other hand is connected to the rectifier (tube or SS), the pilot light, the mains switch et.c. and is often located farthest away from the input tubes.

Could you post a few pics of the amps? That would make it a lot easier to help you. Also if you could tell us what brands and models the amps are.

Good luck!

ce24 · March 3rd, 2008, 05:31 PM

I'll do that tonight when I get home...Thanks

CE24

JohnnyCrash · March 3rd, 2008, 06:25 PM

PTs generally have:
2 Primaries (usually Black wires).
2 Secondaries (usually Red wires), with a center tap (usually a Red-Yellow wire).
2 Tube Heater Filament supplies (usually Green wires). Sometimes a heater center tap too (most times Green-Yellow).
Usually 2 rectifier heater wires (most often Yellow).

Sometimes there is a bias supply wire too.

OTs generally have:
A black ground wire.
A main voltage wire (usually Red).
A wire for each tube's (or pair of tubes) plates (usually a Blue and a Brown).
One to three secondary wires (different impedance taps of varying colors).

If you got the trannies from the same amp, the PT is generally the larger of the two trannies.

ce24 · March 3rd, 2008, 08:39 PM

here is one amp...making sure I know how to post pics...

Cheers ce24

ok got it I'll post again after i take the pics and get them on my band site.

quackerz · March 3rd, 2008, 08:44 PM

That thing is tiny!

ce24 · March 3rd, 2008, 10:11 PM

some are tube radios but I'm sure that something can be salvaged.

What do you think? I also have 3 butter tubs of orange drops/the red colored ones too. and 3 tubs of resistors that I'm getting.

Cheers
ce24

guess the pics wont play and I cant delete this post I'll try one more time

March 3rd, 2008, 02:13 PM	#1 (permalink)
ce24 Tele-Meister Join Date: Jan 2008 Location: Idaho Age: 58 Posts: 469	PT vs OT difference Well I've got the amp build bug and I have come across a number of old amplifiers of various types that I can scavenge what looks tobe some real nice transformers and lots of other parts. I've been looking at different sites and haven't been able to find some designation of how to tell them apart...They look the same in their different styles. any web sites to look at for info. plus what wires do what? Thanks ce24 OK PT multiple taps OT has three wires coming out of it. __________________ www.motagator.net/slackwater "you can be happy or you can be miserable..the amount of work is the same" Last edited by ce24; March 3rd, 2008 at 03:03 PM.

March 3rd, 2008, 05:08 PM	#2 (permalink)
tazzboy Friend of Leo's Join Date: May 2005 Location: Eugene, Oregon Age: 31 Posts: 3,188	PT = Power Transformer OT = Output Transformer __________________ tazzboy

March 3rd, 2008, 05:23 PM	#3 (permalink)
ce24 Tele-Meister Join Date: Jan 2008 Location: Idaho Age: 58 Posts: 469	I wasn't very clear was I? I know OT and PT, if they aren't stamped is it just the number of wires that tell you which one it is? Thanks CE24 __________________ www.motagator.net/slackwater "you can be happy or you can be miserable..the amount of work is the same"

March 3rd, 2008, 05:31 PM	#5 (permalink)
ce24 Tele-Meister Join Date: Jan 2008 Location: Idaho Age: 58 Posts: 469	I'll do that tonight when I get home...Thanks CE24 __________________ www.motagator.net/slackwater "you can be happy or you can be miserable..the amount of work is the same"

March 3rd, 2008, 10:11 PM	#9 (permalink)
ce24 Tele-Meister Join Date: Jan 2008 Location: Idaho Age: 58 Posts: 469	here's the pix of amps n stuff some are tube radios but I'm sure that something can be salvaged. What do you think? I also have 3 butter tubs of orange drops/the red colored ones too. and 3 tubs of resistors that I'm getting. Cheers ce24 guess the pics wont play and I cant delete this post I'll try one more time __________________ www.motagator.net/slackwater "you can be happy or you can be miserable..the amount of work is the same"

March 3rd, 2008, 05:24 PM	#4 (permalink)
4 Strings Tele-Meister Join Date: Jun 2007 Location: Gossip County Posts: 276	"I have come across a number of old amplifiers of various types that I can scavenge" Sounds interesting, TELL US MORE! I may over simplify a bit, but along with some other guys' tips this may help you: The OT has two of its leads - its secondaries - attached to the speaker jacks (or at last one of them, one may be grounded to the transformer Tweed Deluxe OT style, in which case only one of the leads go to the speaker output). The PT on the other hand is connected to the rectifier (tube or SS), the pilot light, the mains switch et.c. and is often located farthest away from the input tubes. Could you post a few pics of the amps? That would make it a lot easier to help you. Also if you could tell us what brands and models the amps are. Good luck!

March 3rd, 2008, 06:25 PM	#6 (permalink)
JohnnyCrash Poster Extraordinaire Join Date: Mar 2005 Location: Lost Angeles and Orange County Posts: 7,128	PTs generally have: 2 Primaries (usually Black wires). 2 Secondaries (usually Red wires), with a center tap (usually a Red-Yellow wire). 2 Tube Heater Filament supplies (usually Green wires). Sometimes a heater center tap too (most times Green-Yellow). Usually 2 rectifier heater wires (most often Yellow). Sometimes there is a bias supply wire too. OTs generally have: A black ground wire. A main voltage wire (usually Red). A wire for each tube's (or pair of tubes) plates (usually a Blue and a Brown). One to three secondary wires (different impedance taps of varying colors). If you got the trannies from the same amp, the PT is generally the larger of the two trannies.

March 3rd, 2008, 08:44 PM	#8 (permalink)
quackerz Tele-Holic Join Date: Sep 2006 Location: New Jersey Age: 45 Posts: 924 8 Photos	That thing is tiny!