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archimedes
Silver Member
United Kingdom
191 Posts |
 Posted - 09/10/2009 : 22:21:45
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Hi
I have a PH-1 from 1981 which I have just taken apart to fix a broken input jack (no I didn't break it using in-line connectors!) and it set me wondering if there is any point in upgrading / updating any of the caps on the signal path to reduce noise. Some of them such as C1 are green and flat and could be metal film in any case but I am not sure. Others such as C9 are electrolytic which I believe can degrade over time. I have to admit that apart from these two which are obviously on the signal path I am not too sure what else is. Also is there any way of making the phase shift a little deeper? Any advice gratefully received.
David |
Edited by - archimedes on 09/10/2009 22:21:59 |
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cctsim
Silver Member
United Kingdom
418 Posts |
Posted - 09/11/2009 : 00:31:46
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C2, C3, C4, C5 and C12 are 10 nF metal film capacitors and all in signal path. Panasonic metal film type is a good substitute for these.
C7 and C8 are 47pF ceramic capacitors and also in the signal path.
Silver mica type is a good substitute for these.
C6 1uF electrolytic can also be replaced with Panasonics.
C11 is also a 15uF electolytic in the signal path. This one could be a bit difficult to find.
C10 is 47uF in the 4.5V bias voltage divider.
C20 is 100uF in the power supply filtering.
The rest of the capacitors are in the switching parts of PH1.
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Edited by - cctsim on 09/11/2009 00:34:06 |
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archimedes
Silver Member
United Kingdom
191 Posts |
Posted - 09/11/2009 : 08:49:20
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Many thanks!
p.s. I also figured out along the way that the components that need removing and jumpering for ACA to PSA power supply conversion so that it will work without a daisy chain on a 9v supply are D5 and R45. This may be of use to someone.
p.p.s. I should also have said that my PH-1 is running on two TL074s which have reduced the noise, flattened out the tone nicely and I think possibly deepened the shift a tad. A friend of mine who works in electronics for a living recommended them and fitted the chip adapters. It's a pretty beat up PH-1 so I don't have any qualms about modding it as the main if not only reason I have it is to use it. This also means that I have the 3403s available for other things, they are supposed to be really good in an OD-1 aren't they? Shame I don't have one!
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Edited by - archimedes on 09/11/2009 12:17:37 |
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 09/11/2009 : 14:38:54
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Hi archimedes
quote:
This also means that I have the 3403s available for other things, they are supposed to be really good in an OD-1 aren't they? Shame I don't have one!
Very cool - keeping the 3403's.
Yes you could use one to build the very first version of the 'all op-amp" OD-1
I don't own one of that era, but have it on good recommendation that they are better sounding tone wise, than the later hybrid 4558-discrete versions.
I do own a couple of the Rev-E OD-1's - as I have not been able to find anything older here in Oz.
Do you have the Sch. for the 3403 OD-1's?
PM me if you don't.
I believe I saw a Vero/PCB clone 3403 version, on one of the German pedal enthusiasts sites, but I can't remember the web link.
Regards Dr. Bob
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archimedes
Silver Member
United Kingdom
191 Posts |
Posted - 09/11/2009 : 15:06:10
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quote:
Originally posted by Dr. Bob
Very cool - keeping the 3403's.
Yes you could use one to build the very first version of the 'all op-amp" OD-1
I do have a schematic marked OD-1A which seems to include the 3403 so maybe I'll just have to build one some time, it looks fairly simple. Now there's a thought! |
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Boss PH-1 cap changes?
