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Post subject: PT for 5E3?
Posted: Tue Dec 10, 2019 6:37 pm
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Hi all.

I have a PT that came out of an organ, Part No. A0_22111 4 that I'd like to use in a 5E3 build but need a check on the voltages.

This is what I found when testing it with no load on the bench
Red-Red = 673 v
Red-Yel CT = 336 v
Yel - Yel = 5.8 v
Brn-Brn = 6.8
Brn - Grn CT = 3.4.

Does this look acceptable? I was advised elsewhere that the PV is going to be too high for my needs but I'm not ready to toss it without another check. I haven't found the specs for this exact part No. but it came from a Hammond AO-29 chassis.


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Post subject: Re: PT for 5E3?
Posted: Tue Dec 10, 2019 9:07 pm
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The loaded voltages will be lower. I think you will be alright.
Most of the Hammonds used 6V6 for outputs. The pics of the A0-29 chassis looks like it has 6V6s in it.


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Post subject: Re: PT for 5E3?
Posted: Tue Dec 10, 2019 10:25 pm
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TimsAudio wrote:
The loaded voltages will be lower. I think you will be alright.
Most of the Hammonds used 6V6 for outputs. The pics of the A0-29 chassis looks like it has 6V6s in it.


Thanks. I couldn't find solid specs on the trans but it should provide a ton of current with the tubes it was driving: 1, 5U4,,1-6B6,,2- 6V6,,2-12AU7,,1-12AX7,,2-6C4,,2-6AU6.

I wouldn't be opposed to a 5E3 with 6L6's either.


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Post subject: Re: PT for 5E3?
Posted: Fri Dec 13, 2019 5:12 pm
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The available voltage taps seem to be a bit "overkill" for a 5E3 but with a correctly-designed voltage dividing network it should work fine.

The 673-volt tap would be more than adequate to drive a pair of 6L6GC's or 5881's should you so choose.

Arjay

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Post subject: Re: PT for 5E3?
Posted: Sun Dec 15, 2019 12:33 pm
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Retroverbial wrote:
The available voltage taps seem to be a bit "overkill" for a 5E3 but with a correctly-designed voltage dividing network it should work fine.

The 673-volt tap would be more than adequate to drive a pair of 6L6GC's or 5881's should you so choose.

Arjay


Thank you Arjay. I also have a PT pulled from a 50's Motorola record player that ran 6V6's. Data sheet says 600VCT (tested 612VCT with 121VAC on primary) at 93ma and 2A on the heaters. It looks a tad small for that rating but apparently packs a punch for it's size. I suppose I could use that.

My reasoning for picking the overkill behemoth PT was so I could use 6L6's if I wanted but it isn't necessary, and to eliminate or reduce sag for a tighter bottom end but that last part is mostly my own SWAG.


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Post subject: Re: PT for 5E3?
Posted: Sun Dec 15, 2019 1:06 pm
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If you really wanted to eliminate or reduce P/S sag you could always replace the tube rectifier with a Weber Copper Cap. But sag is part and parcel of the traditional 5E3 tone so you'd be making a trade-off. More food for thought.

Arjay

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Post subject: Re: PT for 5E3?
Posted: Wed Feb 12, 2020 11:29 pm
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Thanks Retro.

I've been delayed a couple of weeks so no progress yet, and I have just one day off before leaving again for another week so hopefully I'll get to break ground when I get back.

I like the 5E3 the way it is. If I could put anything on a wish list it would be to have more of a blackface clean at low volume. That's not a must-have and I can mess with the tone stack if it bugs me enough, but I doubt it will. I don't want to mess around and lose that snarl.

I have another PT with 310VAC @ 93ma (IIRC) that also ran a pair of 6V6's. It's also a pull from a 50's (Motorola) console player. Can you tell me what tonal effect if any I would notice using the 310v over the 336v? Seems I read lower voltage makes the amp more touch sensitive when played, or maybe it was higher voltage. I'm not sure and I can't find that thread again.

Many thanks.


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Post subject: Re: PT for 5E3?
Posted: Wed Feb 12, 2020 11:58 pm
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I think you're correct about the lower B+ providing more touch sensitivity but as far as getting a clean blackface tone (at any volume) it ain't gonna happen due to the 5E3's tone control configuration and its location within the signal chain. You might have to build two amps to fulfill those parameters.

Arjay

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Post subject: Re: PT for 5E3?
Posted: Thu Feb 13, 2020 12:48 am
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Retroverbial wrote:
I think you're correct about the lower B+ providing more touch sensitivity but as far as getting a clean blackface tone (at any volume) it ain't gonna happen due to the 5E3's tone control configuration and its location within the signal chain. You might have to build two amps to fulfill those parameters.

Arjay


Thanks Arjay!


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Post subject: Re: PT for 5E3?
Posted: Thu Feb 13, 2020 7:51 pm
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I agree with Arjay and Tim, I wouldn't put too stiff power supply into that amp. You are going to lose its tweed magic. The original PT is okay, right?

I suppose you could keep the 5Y3GT in the amp. That would keep most of the sag and drop the B+, even with the bigger PT. I think?!?

:?:


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Post subject: Re: PT for 5E3?
Posted: Thu Feb 13, 2020 10:21 pm
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BMW2002Ti wrote:
I suppose you could keep the 5Y3GT in the amp. That would keep most of the sag and drop the B+, even with the bigger PT. I think?!?


+1

The 5Y3GT should be sturdy enough to support a B+ of +/- 325 VDC.

Arjay

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