I have not been here for two years, I do have a question

[catnine]

 I built an amp using a fender MM bass amp chassis that was in need of help . I stripped it and installed an Allen amps PT that is a beefed up champ/princeton PT , it was a drop in fit and allowed the use or 6V6's or 6L6's and it either has 325-0-325 with 180 mA or 310-0-310 with 150 mA , when I got it it was listed at the 325 VDC , I believe it is a TP25 , the instuctions came with it said 310 VDC.

 I used a Allen amps OT for a Deluxe or princeton an TO 25 which is no longer offered yet it has two secondaries that used with 6V6's you have either 4 or 8 ohm taps and with 6L6's 2  or 4 ohm taps.

 Since the MM bass amps chassis has only a vol and tone and two input jacks what I did was use the front end of  princeton 6G2 and left off the trem circuit. This allowed me to use the vol and tone pots as the only controls. I then used a 5E3 power section and since the 6G2 uses 1/2 of V1 and 1/2 of V2 for the PI I wired mine up like the 5E3 which V2 is the PI and V1 is just the one triode preamp. I did this because this began as a sort of 5E3 and it allowed me to use a 12AY7 as the preamp tube for less gain , I like headroom.

 On the power section I changed it from a cathode bias to an adjustable fixed bias to provide a way to swap the 6V6's for the 6L6's and the reverse. The PT has a 50V bias tap which I used and had to select the proper bias resisters so I could use either tube.I used the 5k and 22k dropping resisters like the 5E3 . How is it that voltages are very close to the AA1164 princeton. Even with a 5Y3 rect tube . I don't know much about math but somehow it workled out . Is it just the extra Ma of the PT and larger OT or just shear luck?
I

[jjasilli]

Wow, it's been 2 years!

I changed it from a cathode bias to an adjustable fixed bias to provide a way to swap the 6V6's for the 6L6's : nothing wrong with fixed bias, but with cathode bias 6V6's and 6Lt's can be swapped and use the same cathode resistor; it balances out.  Alternately, cathode bias can be changed by splitting the cathode resistance into 2 resistors in series, and using a SW to short one out. 

How is it that voltages are very close to the AA1164 princeton. . .Is it just the extra Ma of the PT and larger OT or just shear luck? 325 and 310 are within 10% of one another, which is smaller than the margin of error for transformers.  Also modern trannies tend to be rated for 115VAC primaries, but wall voltage tends to be about 123VAC.  Your tranny is stepping-up the wall voltage about 2.7X, so this throws about an extra 20VAC "into the mix" on the secondary side.

[PRR]

> installed an Allen amps PT that is a beefed up champ/princeton PT
> How is it that voltages are very close to the AA1164 princeton.

You used a Princeton PT, you got Princeton voltages...... what was the question?

[catnine]

> installed an Allen amps PT that is a beefed up champ/princeton PT
> How is it that voltages are very close to the AA1164 princeton.

You used a Princeton PT, you got Princeton voltages...... what was the question?

 Actually not really. My line voltage at night when it is at the highest is 119 VAC . And I built the amp as I said with a 6G2 front end and a 5E3 power section . The AA1154 prinecton uses a GZ34 rect tube rather a 5u4gb I use a 5Y3 and it is not a stock Princeton PT it is beefed up and instead uses 150 mA instead of the standard 70 mA PT used on AA763 silver faced champs and also 6G2 princetons . I also use one less 12ax7 because I don't have the trem circuit and I do have the fixed /adj bias of a 6G2.  My amp has 1/2 of the preamp tube in play and no reverb so yes my question is why my voltages are close to a AA 1164 or even a princeton AA964 and my build uses a 5000K 1st dropping resister and a 22K second dropping resister. The 6G2 uses a 1k and a 10 K the AA 1164 with reverb and trem uses a 1k, a 18k and a 18K which is even less than I am using so that is my question.

[RicharD]

>my question is why my voltages are close to a AA 1164 or even a princeton AA964

So.... you took a bunch of bits -n- pieces of different circuits and stuck em together like legos and you're curious why your voltages are close to a know circuit.  I'd say luck, that and all those various AB763, AA1154, EIEIO circuits tend to act just about the same.  Splatting out a bunch of this that and what nots makes it impossible to analyze a circuit.  Simply telling me you have X value for a dropping resistor tells me absolutely nothing.  I have no clue what's connected to it.  Probably a bunch of tubes.  Post an entire schematic and someone will slice -n- dice it all proper like for you.

[catnine]

>my question is why my voltages are close to a AA 1164 or even a princeton AA964

So.... you took a bunch of bits -n- pieces of different circuits and stuck em together like legos and you're curious why your voltages are close to a know circuit.  I'd say luck, that and all those various AB763, AA1154, EIEIO circuits tend to act just about the same.  Splatting out a bunch of this that and what nots makes it impossible to analyze a circuit.  Simply telling me you have X value for a dropping resistor tells me absolutely nothing.  I have no clue what's connected to it.  Probably a bunch of tubes.  Post an entire schematic and someone will slice -n- dice it all proper like for you.

 It's not really like I had no plan or thought this out and took a bunch of bits and pieces and stuck them together like legos . It was two simple curcuits put together with a different PT and OT . I don't have a drawing or I would have provided one. I see from two replies that there would be no point , it is not that important really. The amp is well thought out and well planned and it works . It does not require a mastermind to take a princeton 6G2 after the tone stack before the PI  and feed it into a 5E3 power section and change the cathode bias into a adj/fixed bias.

[catnine]

I'll answer my own question . Provided I have only 119VAC line peak and don't have the trem circuit of a 6G2 there for 1/2 of a 12ax is not used and since the dropping resisters are 5k and 22K where the 6G2 uses 1k and 10K then I would assume the PT with the 5Y3 as a rect is where the later black faced princtons used a stiffer rect that the PT is why I have higher voltages than a 6G2 or 5E3. The larger OT may also play a part.

[jojokeo]

I'll answer my own question . Provided I have only 119VAC line peak and don't have the trem circuit of a 6G2 there for 1/2 of a 12ax is not used and since the dropping resisters are 5k and 22K where the 6G2 uses 1k and 10K then I would assume the PT with the 5Y3 as a rect is where the later black faced princtons used a stiffer rect that the PT is why I have higher voltages than a 6G2 or 5E3. The larger OT may also play a part.

I'm sorry but I can't exactly figure out what the questions are either except as to guess that you're wondering why your voltages are what they are and that you've measured them as? If the amp works, sounds good, and is reliable then why is there a question (or doubt?) in the first place?

In any case, I will guess "out loud" for a sec: you have a beefed up power supply so voltages w/ be a bit higher than normal but we still don't, know and you don't either, exactly which (out of production) PT you actually have installed correct? Anyway, you will get less voltage drop from the 5ar4 recto and more drop by using a 5y3 so this puts things back down "more to normal levels" of your Princeton circuit and iron w/ the princeton power resistors. But you also have used higher dropping resistors which is also helping to drop more voltage than normal. So in the end, your voltages have been corrected and it's all a wash!? If this was all planned and/or calculated then it could be considered skill. If it was just thrown together (which it sounds like) since you have no schematic or other concrete info then I'd say just plain lucky but also w/ a bit of understanding sprinkled in. Is this simply what you're trying to find out and/or confirm here?

[catnine]

I'll answer my own question . Provided I have only 119VAC line peak and don't have the trem circuit of a 6G2 there for 1/2 of a 12ax is not used and since the dropping resisters are 5k and 22K where the 6G2 uses 1k and 10K then I would assume the PT with the 5Y3 as a rect is where the later black faced princtons used a stiffer rect that the PT is why I have higher voltages than a 6G2 or 5E3. The larger OT may also play a part.

I'm sorry but I can't exactly figure out what the questions are either except as to guess that you're wondering why your voltages are what they are and that you've measured them as? If the amp works, sounds good, and is reliable then why is there a question (or doubt?) in the first place?

In any case, I will guess "out loud" for a sec: you have a beefed up power supply so voltages w/ be a bit higher than normal but we still don't, know and you don't either, exactly which (out of production) PT you actually have installed correct? Anyway, you will get less voltage drop from the 5ar4 recto and more drop by using a 5y3 so this puts things back down "more to normal levels" of your Princeton circuit and iron w/ the princeton power resistors. But you also have used higher dropping resistors which is also helping to drop more voltage than normal. So in the end, your voltages have been corrected and it's all a wash!? If this was all planned and/or calculated then it could be considered skill. If it was just thrown together (which it sounds like) since you have no schematic or other concrete info then I'd say just plain lucky but also w/ a bit of understanding sprinkled in. Is this simply what you're trying to find out and/or confirm here?

 Once again this build was hardly "thrown together" I don't have a drawn out schematic , I built it off the fender field guide diagrams , chose a PT that is an Allen amps TP25 because it is a drop in fit in a fender music master bass amp chassis which is the same chassis in size as a silver faced champ and this PT would give me the power to run a push/pull 6V6 amp. I wanted it simple so I chose the 5E3 power section yet only had two inputs and a vol and tone control, this is where the 6G2 input preamp and tone stack was a great choice . I had no place to fit the trem circuit of the 6G2 and never cared for trem so all I had to do was leave that part of the circuit out . it is all wired proper . The PT does have 150mA spec which is over twice the 70mA of a stock princeton PT used in later champs and the 6G2 . I attached a photo of the inside of the chassis . Next to the input jacks between them and the first pot there is an none connected input jack because I did have a blackface tone stack in there to try it the jack is just a way of filling the hole.

[catnine]

 Since i had the chassis out last night I took readings and drew up a hand drawn schem with voltages . The PT I wrote 2.0mA on the rect , it is 2.0 amp and I put 4.5Ma for the heater it is 4.5 amp. The bias board is on the far left of the eyelet board just to the left of the first filter cap and there is a 50 k pot through the bottom of the chassis so I can set the bias without removing the chassis and using a bias rite.

 Here is the hopefully readable schematic .

[DummyLoad]

How is it that voltages are very close to the AA1164 princeton. Even with a 5Y3 rect tube . I don't know much about math but somehow it workled out . Is it just the extra Ma of the PT and larger OT or just shear luck?

You used a Princeton PT, you got Princeton voltages...... what was the question?

my answer.

You used a Princeton PT, you got Princeton voltages. + the load of missing princeton preamp tubes is essentially insignificant.

not documenting a build is not well thought out. if you have to replicate or service the device, then you're relying solely on memory and that fades. guaranteed. you then have to waste time reverse tracing what you did; granted a two knob fender is not rocket science, but still...

--DL

[catnine]

 While I had the chassis out last night I removed the dummy jack and installed a switch so I can have the no NFB of the 5E3 and the 56k NFB of the 6G2 . here is the photo and the schem... I put the wrong photo that was not wired proper so I replaced it to how it is actually wired . I had both ends of the bypass cap and 56k NFB resister to ground . I had to run a wire to the cathode of the 12ax7 for it to work . I never powered up the amp , I was tired but saw the problem right away.

[catnine]

How is it that voltages are very close to the AA1164 princeton. Even with a 5Y3 rect tube . I don't know much about math but somehow it workled out . Is it just the extra Ma of the PT and larger OT or just shear luck?

You used a Princeton PT, you got Princeton voltages...... what was the question?

my answer.

You used a Princeton PT, you got Princeton voltages. + the load of missing princeton preamp tubes is essentially insignificant.

not documenting a build is not well thought out. if you have to replicate or service the device, then you're relying solely on memory and that fades. guaranteed. you then have to waste time reverse tracing what you did; granted a two knob fender is not rocket science, but still...

--DL

 I just posed a photo and a schem hand drawn but it's the best I could do and besides the circuit is VERY simple I know it by heart and there are the fender feidl guides if I need them and a few books with the schems I have here.

[jojokeo]

I think this was just a simple communication breakdown and you're showing your work for us to see!?
Your amp looks well done and you acheived your goal. Good work on your build. I'm sure it's much better than the stock MM circuit I'm sure. If it was mine though, I'd parallel that first 12ax7 but then you'd have to adjust your cathode & load resistors for the same response. I'm sure you know that. I bet it sounds great.

[catnine]

I think this was just a simple communication breakdown and you're showing your work for us to see!?
Your amp looks well done and you acheived your goal. Good work on your build. I'm sure it's much better than the stock MM circuit I'm sure. If it was mine though, I'd parallel that first 12ax7 but then you'd have to adjust your cathode & load resistors for the same response. I'm sure you know that. I bet it sounds great.

Thank you . I thought about a parallel circuit on the pre amp tube .  I did wire one amp with a parallel 12ax7 but never really understood the advantage . I used a 12 AY7 instead of a 12ax7 , 12ax7 was too much breakup . Even with the 56K NFB on a switch the amp should act more like a 6G2 but still the 12ax7 was too much breakup , perhaps that's the way a 6G2 sounds , don't know I never played through one. Also when I first built this amp I used a weber 12 inch silver bell with the ceramic magnet 30 watt yet even with the tone on full treb it sounded fine , anything past three was getting sort of full on bottom and little highs . I had a weber sig 12 s alnico and installed that and then the tone worked full sweep and gave me much more control. Most likely because the silver bell was a higher powered stiffer speaker and if I cranked up the vol then the tone worked much better but by then the amp was far too loud, the sig 12 is also loud but works better at room levels .