PT Wiring

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Cygnus X1
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Location: Midlands South Carolina

Re: PT Wiring

Post by Cygnus X1 »

I'll go ahead and use the diodes I have.
I usually use tube rectifiers, but this amp doesn't call for it,
so I didn't know there was a difference in the 4007's when I bought them.

I'm using a 6550 in this amp. It calls for a KT88.
But that's a whole other thread:
http://ampgarage.com/forum/viewtopic.php?t=5647
tubetek
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Joined: Wed Mar 08, 2006 8:04 pm
Location: RedRiverGorge, KY.

Re: PT Wiring

Post by tubetek »

UF4007 exhibit less switching noise than the 1N4007. An old-school fix is to bypass each 1N4007 with a .01mFD, 1000Volt ceramic capacitor. (but Fender and others built many amps using un-bypassed 1N4007s) This works well for standard full-wave OR bridge Recto setups. HTH
Tom
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Luthierwnc
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Location: Asheville, NC

Re: PT Wiring

Post by Luthierwnc »

I'm sorry. I saw the AX84 and didn't blow up the schematic to check the power tube. Your draw will be double what I said in my previous post. That won't make a big enough difference not to stick with the same voltage ratios on the trannie.

I made one like this last winter and it came out really well. Mine is based on the class act except I used a panel switch instead of the alternate jacks to engage the extra gain stage. It was built for a KT66 but I liked a 6L6 better. There are stories out there on an amp called the "Octal Fatness" using a pentode front-end. I only mention it because the schematics from New Zealand show the resistor values for a variety of power tubes. Worth a look.

sh
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Cygnus X1
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Re: PT Wiring

Post by Cygnus X1 »

tubetek wrote:UF4007 exhibit less switching noise than the 1N4007. An old-school fix is to bypass each 1N4007 with a .01mFD, 1000Volt ceramic capacitor. (but Fender and others built many amps using un-bypassed 1N4007s) This works well for standard full-wave OR bridge Recto setups. HTH
Tom
Please elaborate for me.
Does this mean putting a cap in between each diode in the bridge configuration...like diode/cap...to diode/cap etc, all the way"around"
the series of four?

Or do the caps get one leg routed to what becomes ground in the chain?

I'm going slow at this point. weekdays don't offer much quality time for building, so reading the advice of the much more knowledgeable is the wisest use of my limited time! :)

I also think I should should shoot for the voltages described on the schematic, before playing with other options...let me get this engine running first, then adjust valve lifers and whatnot later, I think.
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Ears
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Location: New Zealand

Re: PT Wiring

Post by Ears »

Cygnus X1 wrote:
tubetek wrote:UF4007 exhibit less switching noise than the 1N4007. An old-school fix is to bypass each 1N4007 with a .01mFD, 1000Volt ceramic capacitor. (but Fender and others built many amps using un-bypassed 1N4007s) This works well for standard full-wave OR bridge Recto setups. HTH
Tom
Please elaborate for me.
Does this mean putting a cap in between each diode in the bridge configuration...like diode/cap...to diode/cap etc, all the way"around"
the series of four?

Or do the caps get one leg routed to what becomes ground in the chain?

I'm going slow at this point. weekdays don't offer much quality time for building, so reading the advice of the much more knowledgeable is the wisest use of my limited time! :)

I also think I should should shoot for the voltages described on the schematic, before playing with other options...let me get this engine running first, then adjust valve lifers and whatnot later, I think.
Cygnus, if you would take the time to read power supply material on both the websites I cited earlier you will find the answer to this and more.
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Cygnus X1
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Location: Midlands South Carolina

Re: PT Wiring

Post by Cygnus X1 »

Ears wrote: Cygnus, if you would take the time to read power supply material on both the websites I cited earlier you will find the answer to this and more.
Yeah, I know (hangs head a bit sheepishly)...I glanced.
Looking for easy answers doesn't teach me. I'm just trying not to fry anything because I missed something that is so glaringly obvious to others who have more experience.

I promise...I shall read!
(I'll still have some questions, though...I know me) :)

Thank you, Ears...and all.
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Luthierwnc
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Re: PT Wiring

Post by Luthierwnc »

Each diode has a parallel cap. If you look at late Fender silverface schematics you'll see how they are arrayed. I wouldn't bother for what you're making.

You can also get bridges already configured in plastic cases for a buck and a half. In the larger sizes they usually have a mounting hole in the middle and legs on the corners. Either you can drop them into turrets/lugs or just mount them upside down and tie off the leads on the legs. Here's a Mouser example:

http://www.vishay.com/docs/88613/gbpc6.pdf

sh
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Ears
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Location: New Zealand

Re: PT Wiring

Post by Ears »

Cygnus X1 wrote:
Ears wrote: Cygnus, if you would take the time to read power supply material on both the websites I cited earlier you will find the answer to this and more.
Yeah, I know (hangs head a bit sheepishly)...I glanced.
Looking for easy answers doesn't teach me. I'm just trying not to fry anything because I missed something that is so glaringly obvious to others who have more experience.

I promise...I shall read!
(I'll still have some questions, though...I know me) :)

Thank you, Ears...and all.
The valvewizard site is particularly specific to guitar amps. In fact it makes for a good little (and free) reference book.
Select all the text and pics in webpage, copy it then paste into Word or similar, tweak position of the pictures in the page and then print it. Keep it in a clear-file. Each web page makes for a neat 2 to 6 page chapter. I understand that that website is actually a dry run for possible future hard copy publication.
Aiken material is also worth treating the same way.
joebob
Posts: 82
Joined: Sun May 18, 2008 11:43 am
Location: Georgia

Re: PT Wiring

Post by joebob »

Jack Darr's series on guitar amps has 2 sections on power supplies. One has quite a bit of info on the tube and SS rectifiers.

http://www.pacificrecone.com/JackDarrBook.html

And as mentioned earlier 'The Valve Wizard' has excellent info too.

http://www.freewebs.com/valvewizard/index.html

I am building the AX84 p1 extreme and putting in a 5u4gb recifier tube instead of the SS recitifer. I am using a 5881wxt, Hammond 270FX PT and MPS OT10SE OT. I am just staring to paint the chassis today, I have already built the board and populated it with the parts.

Dave
Instructions...I don't need no stinkin instructions
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Cygnus X1
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Location: Midlands South Carolina

Re: PT Wiring

Post by Cygnus X1 »

Thank you, all...


I'm breaking it in as I type. (Running a radio through it).
:D

Not only did I read the treatises recommended, I went back to the old college book, and of course, it was me just blocking my own knowledge.
I already knew it, but still, I don't alter power supplies! So the cowbwebs get really thick....

But the AX84 SEL sounds really good for high gain, I made some changes to the layout and star grounded it...so it is quiet as well as having plenty of gain. It doesn't push a lot of bass, but the plan calls for a clean power section, and saturation in the preamp.
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