[sdiy] demagnetising spring reverbs

[Harry Bissell]

Iwonder if that is a good idea at all... how will you demagnetize the drive coil assembly but
NOT demagnetize the tiny little magnet that is glued on the spring.

Why not take a small piece of ferrous metal, and see if it sticks to the drive coil assembly...
if not you probably don't need to de-magetize.

think... would you want to de-magetize a guitar pickup ?  :^)

H^) harry 


----- Original Message -----
From: Eric Brombaugh <ebrombaugh1 at cox.net>
To: synth-diy at dropmix. xs4all. nl <synth-diy at dropmix.xs4all.nl>
Sent: Wed, 12 May 2010 09:35:47 -0400 (EDT)
Subject: Re: [sdiy] demagnetising spring reverbs

I wonder if a tape head demagnitizer would work?

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=400029874181&rvr_id=&crlp=1_263602_263622&UA=M*F%3F&GUID=8167aee21250a0aad5326dd2fce85c78&itemid=400029874181&ff4=263602_263622

Eric

On May 12, 2010, at 3:04 AM, James Dunn wrote:

> Hi list,
> 
> Some time ago I came across a suggestion to increase the signal to noise ratio in the ARP 2600 reverb unit by reducing the value of R273 by half. I tried this mod and it was indeed louder but after a while the reverb seemed to deteriorate. It now sounds very muddy and distorted. I looked at the signal being sent to the reverb tank on a scope and it was also distorted, although it only had a minor glitch when I disconnected the tank. So I concluded that the tank must be faulty (probably by overdriving it). This <http://sound.westhost.com/project34.htm> website would seem to confirm this - it says:
> 
>> ...but you must be very careful, because overdrive causes the small pole piece to become magnetically saturated, leading to gross distortion that increases with decreasing frequency
> 
> So my question is how can I demagnetise it or otherwise repair the tank? I know there was some discussion a while ago about repairing tanks, but not specifically demagnetising...
> On the other hand, should I just buy a new tank? Where can I get one?
> 
> many thanks
> 
> James
> 
> PS - the transducer input impedance is 175 ohms and I temporarily connected another tank which worked fine.
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-- 
Harry Bissell & Nora Abdullah 4eva