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PPP KT66, Jensen P15N, Hammond PowTran 378CX/193L Choke

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Layberinthius

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Joined 2004
#1
I know I can use the Hammond 378CX (400-0-400 465mA) for Power Transformer and Hammond 193L (5H 300mA) choke...but.

http://www.triodeel.com/acpppar.gif

What OPT can I use with this schematic?

I've looked at Hammonds 1650K OPT capable of PPP however it is off by about 400 ohms in respect to the original design, IS this going to affect the operation of the amplifier to an extent that I should be worried and what can I do to counteract it?

And how does it affect the design?

Is there any other OPT's available from someone else?

Can you provide any further advancements to the original schematic's design?

The idea is to construct two 19x19 inch floorstanding boxes and install a pair of bell-cover Jensen P15N's into either one, Then incorporate the quad KT66 into either one with power unit at the bottom and amplification unit at top with upside down KT66 tubes.

This way I can build seperatley the all important midrange/top-end amps later down the track when I'm more keen with tubes but for now "practice" and get the bugs out of my system with the bass..

Improving on the bass amplifier later on.

Cheers!
 
#4
Layberinthius said:
I've looked at Hammonds 1650K OPT capable of PPP however it is off by about 400 ohms in respect to the original design, IS this going to affect the operation of the amplifier to an extent that I should be worried and what can I do to counteract it?
Click to expand...
I presume you mean that the OPT's primary Z in the original design is 400 ohms different from the Hammond. Not enough difference for me to worry about.
The idea is to construct two 19x19 inch floorstanding boxes and install a pair of bell-cover Jensen P15N's into either one
Click to expand...
Why are you using guitar speakers with an Fs of 77hz, an octave above E1? You'll get MUCH better sound from proper bass drivers.
 
#5
Re: Re: PPP KT66, Jensen P15N, Hammond PowTran 378CX/193L Choke

Brett said:
I presume you mean that the OPT's primary Z in the original design is 400 ohms different from the Hammond. Not enough difference for me to worry about.Why are you using guitar speakers with an Fs of 77hz, an octave above E1? You'll get MUCH better sound from proper bass drivers.
Click to expand...


Oh please recommend recommend!


Lately I've been listening to rock a lot however..I'm an odd ball, I like both contemporary psychadelic and classic rock, either rarely come together.

I know that the circuit won't do my sources justice, and the output tranny won't either, but what choice do I have when it comes to a KT66 Push pull parallel? That's what this thread is for.
 
#6
Layberinthius said:


Can I still use it with the schematic above? If so, how?

Sowter U060
Click to expand...
Not directly. The Sowter doesn't have UL taps and the Acro is a UL amp.

Besides, do you really want to spend UKP237 + shipping etc on an OPT? As against $A182 for the 1650K?

I don't want to rain on your enthusiasm, but you have no idea what this amp will sound like, ie will you even like it, so I'm really against a novice builder spending large sums of money up front. Having it not work out the way you want is an even bigger enthusiasm killer.
If you're only going to use this in your bedroom, then it's too much power and expense, for most stage work or jamming with a drum kit it's too small but it might be OK for studio.

FWIW, I play bass, and I build amps on a semi-commercial basis.
 
#7
Brett said:

Not directly. The Sowter doesn't have UL taps and the Acro is a UL amp.

Besides, do you really want to spend UKP237 + shipping etc on an OPT? As against $A182 for the 1650K?

I don't want to rain on your enthusiasm, but you have no idea what this amp will sound like, ie will you even like it, so I'm really against a novice builder spending large sums of money up front. Having it not work out the way you want is an even bigger enthusiasm killer.
If you're only going to use this in your bedroom, then it's too much power and expense, for most stage work or jamming with a drum kit it's too small but it might be OK for studio.

FWIW, I play bass, and I build amps on a semi-commercial basis.
Click to expand...

Thanks for the advice!, Would you consider 6L6 to be a good mid-bass contender? I already have the powtran and tubes...

http://www.triodeel.com/ac6l6280.gif
 
#8
Layberinthius said:
Oh please recommend recommend!
Click to expand...
Budget? Used OK? What are you planning on using this rig for?How low do you want it to go?
Lately I've been listening to rock a lot however..I'm an odd ball, I like both contemporary psychadelic and classic rock, either rarely come together.
Click to expand...
I like both at times. Had the Who blaring most of today.
I know that the circuit won't do my sources justice, and the output tranny won't either,
Click to expand...
Dunno what you mean by that. Is your bass and playing, superb? The Hammond will be fine and it's probably a better OPT than is in most bass amps.
but what choice do I have when it comes to a KT66 Push pull parallel? That's what this thread is for.
Click to expand...
According to the GEC KT66 datasheet, in UL at 450VB+, you're going to get 60W from the PPP KT66's and be running them quite hot doing so. If it were me, I'd go with a pair of 6550, tetrode and a 1650R.

If you're not prepared to experiment a lot, and deal with the expense that involves, copy an existing, known good design (preferably one you can try first like an Ampeg). Just building any amp design and throwing it into a box with a couple of speakers isn't going to get what you want, unless you're extremely lucky.
 
#9
Layberinthius said:
Thanks for the advice!, Would you consider 6L6 to be a good mid-bass contender? I already have the powtran and tubes...

http://www.triodeel.com/ac6l6280.gif
Click to expand...
I was typing when you replied so some of what I said above may not apply.

If you have the PT, what are it's specs?
6L6's are good tubes and can sound great in the right circumstances.
If you can deal with 30W then the second Acro design is better looking. Built plenty of similar stuff. Hammond 1650H ($A178) would work well here.

You'll also need a preamp section. Try the one I've linked below as I know it sounds good as a basis to start from. Tweak the B+ voltages to the pre section with some extra RC sections from your poweramp PSU.
 
#10
This might help
 

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#11
Brett said:
I was typing when you replied so some of what I said above may not apply.

If you have the PT, what are it's specs?
6L6's are good tubes and can sound great in the right circumstances.
If you can deal with 30W then the second Acro design is better looking. Built plenty of similar stuff. Hammond 1650H ($A178) would work well here.

You'll also need a preamp section. Try the one I've linked below as I know it sounds good as a basis to start from. Tweak the B+ voltages to the pre section with some extra RC sections from your poweramp PSU.
Click to expand...


Refer to this reply: PT Specs
 
#13
Giaime said:
I agree with brett: chose strictly bass-related circuits!

My idea:
Pre - Alembic F2b, or Ampeg SVT, mid '70 Fender Bassman
or if you're after a more '50s sound, build a Tweed Bassman circuit.
Power stage: a pair of KT88 or a quad of 6L6 and you can't go wrong! Or if you're in needing for power a 6550 quad is well-know in bass amps.

http://www.kbapps.com/audio/schematics/tubeamps/ampeg/Default.htm
Click to expand...


How about an Ampeg SB-12 PP 6L6GC?

Does anyone have the PT's taps on this specific amp, "by rights" I should be able to use this one I have here...

What kind of OPT should I be looking for aswell? Am I back to square one with this or should I just go and construct another Fender clone? Hey I don't mind! 😀

Ampeg SB-12 Schematic

Last but not least,Is the SB-12 any good? What kind of Drivers should I use, Should I construct an open baffle cabinet?
 
#14
For the transformers, I think anything that's hi-fi and not too outrageus (think Hammond) will be good. For the OPT look for one of abundant power and the right primary Z. Frequency response for a bass amp is not to worry for (i.e. they are full range). For the PT look for a powerful one, with the right voltage, so you won't suffer much about extreme sag, not so good in bass amps. But the schematic you're linking is lacking most of the information you need (ok, for the primary Z of the OT you can copy it from whatever Fender, but for the PT voltages? I assume a 350-0-350 or something...)

For cabinet construction, I admit I'm not an expert. Try to find photos of the model you are interested in, maybe on ebay or something.

But I have to understand you: you point to a 50w design, tube rectifier. So you want just a recording / micked amp, not a powerful 200w jam amp? Are you after power or sound? I think I misunderstood you, if you're after a great tone to record or to be micked, 50w will be enought.

Sorry, my misunderstood!
 
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