Pete Cornish - P-2 guts

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lolbou
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Post by lolbou »

sinner wrote:Transistors are MPSA18??? :roll:
Just as 2N5089 or 2N5088 but with lower noise (1.5dB)...
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ech0es
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Post by ech0es »

simulation on TSC:
Image

A little hump in the mid at 50%, and fully counter clockwise we can see a huge attenuation around 3Khz, as described one the cornish website:
The tone facility on the P-2™ has been designed to provide an attenuation of 14dB at 3KHz when set fully Counter Clockwise.
http://petecornish.co.uk/SAEP-2.html

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dav9rock
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Post by dav9rock »

I'm sorry but the schematic says that the capacitor in tone section is 1nF instead of 10nF as you entered in the TSC

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Post by frequencycentral »

Greg_G wrote:
frequencycentral wrote:I just see babes and boobs. :oops:
You have to click on the big orange button and then wait a while for the time to count down.
Big orange button or babes and boobs.............and you hit the big orange button. :roll:

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Post by lolbou »

dav9rock wrote:I'm sorry but the schematic says that the capacitor in tone section is 1nF instead of 10nF as you entered in the TSC
And what about the generator Z and the load Z? I bet these values are default but they do not really match the real ones. It might affect the sound...
- Are you a mod or a rocker?
- Uh, no, I'm a mocker.

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Post by analogguru »

Oh, oh, oh..... I can see dark clouds coming up across the nimbus.

BTW, my Ibanez FZ5 has an additional input buffer too - the OD-850 already had it.
lolbou wrote: Too bad, and there isn't anything about the varistor and two resistors used on the input jack (his RF stuff?)..
Who cares about this ?
BTW, a varistor is not "RF-stuff" - it only protects against overvoltage. If there is any, a S07K12 or S14K12 should do it.

analogguru
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Post by culturejam »

lolbou wrote:
sinner wrote:Transistors are MPSA18??? :roll:
Just as 2N5089 or 2N5088 but with lower noise (1.5dB)...
I though the MPSA18 usually had higher current gain than the 5088/89?

Skreddy has gone on about how the hFE has an impact on the sound of a Muff. I've never tested this myself.

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Post by lolbou »

analogguru wrote: Who cares about this ?
BTW, a varistor is not "RF-stuff" - it only protects against overvoltage. If there is any, a S07K12 or S14K12 should do it.

analogguru
Well, I do... Quite hard to know what is the blue disk on the blurry pic. I can see resistors. And I thought at first it was a varistor. Or is it a capacitor for RF rejection? This other choice was just a question that I wrote down in brackets...

And I'm interested in the switching board too (many solders on it), looks like a 3PDT?

And the buffer too.
analogguru wrote:Oh, oh, oh..... I can see dark clouds coming up across the nimbus.
Indeed! :D But some more details of the whole unit may have brought thunder or sunshine, delete where inapplicable...
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dav9rock
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Post by dav9rock »

lolbou wrote:
dav9rock wrote:I'm sorry but the schematic says that the capacitor in tone section is 1nF instead of 10nF as you entered in the TSC
And what about the generator Z and the load Z? I bet these values are default but they do not really match the real ones. It might affect the sound...
Yes, it can affect the sound but the comparison is only for the tone stack... I don't think that a change in the generator Z can be a problem to understand how the P2 works... i mean that this graphic is not far from the truth but the cap. is wrong... it's must change it with 1nF to have the right graph

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Post by Ulysse.Gaunarol »

In fact, EchO is right with his simulation, i did a mistake in copying what i have, it's 10nF. (I did it from a handwritten schemo, I can scan it if you want)

Image

Sorry for the inconvenience, let me know if you have others questions.
Last edited by Ulysse.Gaunarol on 22 Aug 2009, 21:52, edited 1 time in total.

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Post by lolbou »

culturejam wrote:I though the MPSA18 usually had higher current gain than the 5088/89?

Skreddy has gone on about how the hFE has an impact on the sound of a Muff. I've never tested this myself.
Yes, slightly higher, or at least the minimal values on the datasheet are lower. I bet you can select equivalent one out a bunch?
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Post by Dirk_Hendrik »

:popcorn:

Glad to see we learned from te mistery Klon schematic!
Sorry. Plain out of planes.

http://www.dirk-hendrik.com

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Post by Dirk_Hendrik »

frequencycentral wrote:I just see babes and boobs. :oops:
so?
What exactly is the problem!? :mrgreen:
Sorry. Plain out of planes.

http://www.dirk-hendrik.com

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Post by madbean »

I needed something fun to do afternoon, so I adapted this from another muff project I have. Maybe I will have time to actually build it :)

I added some power filtering, LED stuff.
P2.pdf

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Post by lolbou »

A fast reverse, the team is getting really efficient.. :lol: :lol:

Thanks Brian...
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Post by culturejam »

Dirk_Hendrik wrote:Glad to see we learned from te mistery Klon schematic!
Dirk, are you suggesting that the above posted schematic might be a fake?

:popcorn:

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Post by modman »

Well have you ever.... :shock:

Thanks Ulysse, for sharing, don't take this personal, but here's the devil's advocate...

If you didn't draw it yourself last night, it's still an important document. Then it's circulating (already sometime) as if this is the P2. That's why gutshots and degooping is still important, although JiM's remarks are the way to go, for now. Counting components. On the other hand, if it's already circulating since 2006, this might explain the source of all rumours.

The only thing that's very suspicious is the use of the Cornish logo - this makes this document a trademark infringement. Why, is this necessary? It really might be some zealous guy's copy past work... but why devote so much time to the logo and none on tracing the mysterious Cornish buffer :scratch:

Even pictures of gooped Cornish boards are important - sad Ech0es didn't take any. But we'll get by, n'est ce pas, mon ami?
briggs wrote:
JOHNO wrote:I dont think this is right. Surely pete cornish would not jump on the bootweek big muff band wagon.
I wouldn't be surprised. It's been thought for a long time that the P-2 was a big muff...
Yeah you cannot jump a bandwagon you're pulling yourself...
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Post by pf_fan »

modman wrote:Even pictures of gooped Cornish boards are important - sad Ech0es didn't take any. But we'll get by, n'est ce pas, mon ami?
Don't forget about pics uploaded by hoppekee here:
https://www.freestompboxes.org/viewtopic.php?f=7&t=4721&

Tone pot is Alpha, B25k...

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Post by ech0es »

On the other hand, if it's already circulating since 2006, this might explain the source of all rumours.
If we look at thegearpage thread about the rehoused P2
He did the rehousing of the Ted Witcher's P-2:
http://www.thegearpage.net/board/showth ... 9&page=257
The ted witcher message is dated of the 28 december 2006, and the schematic is dated 5 december 2006.
The only thing that's very suspicious is the use of the Cornish logo - this makes this document a trademark infringement. Why, is this necessary? It really might be some zealous guy's copy past work... but why devote so much time to the logo and none on tracing the mysterious Cornish buffer :scratch:
The cornish logo can be reproduced with the font "army", the logo on his website and paint, nothing difficult. But yeah, why one circuit and not the other ?
Maybe Paul garisson didn't degooped it because he doesn't have enough space in the new box for the buffer.

pf_fan wrote: Don't forget about pics uploaded by hoppekee here:
https://www.freestompboxes.org/viewtopic.php?f=7&t=4721&

Tone pot is Alpha, B25k...
Maybe the are several version of P2, all builder change their circuits, boss,ibanez, ehx etc...
Moreover, pete cornish do some several adjustment if you order directly from his website, you can ask him to have your own sound. (more bass, less gain etc...)
Last edited by ech0es on 22 Aug 2009, 23:16, edited 1 time in total.

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ech0es
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Post by ech0es »

P2 clone ?

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