GARY HURST CASTLEDINE MK vero layout 9ed15c8d61c1

GARY HURST: Tone Bender MKI – Castledine, 0.15″ Vero

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I wasn’t aware of this version of the MKI until today.  I’m sure you have probably seen the new line of Tone Benders that Sola Sound is releasing.  I noticed that the Stu Castledine version was on vero, and the rest were all on the more familiar MKI board. 

So after a little digging, it turns out this is based on a very early Tone Bender that Stu has – so early in fact that Gary Hurst said that it was rehoused from one of the original wooden enclosures.

Here’s a link to a site that Graham Green used to run, talking about the providence of Stu’s MKI.   The excerpt below, as it is quite a long article.  Graham has several original MKIs and is a keen collector and historian of early guitar pedals (British in particular).

Of the wooden ones though that’s very different!! To the best of mine (and Garys) knowledge, (as well as many many contacts with similar interests) this is the last complete original example. A friend Stu has one that has the same board but clearly re-housed in an early prototype metal case (with no battery Hatch – Gary acknowledges that to be the case with that particular pedal) 

GARY HUSRT MKI TONE BENDER – CASTLEDINE 0.15″ VERO LAYOUT

UPDATE:  After taking a close look at the values on a Reverb listing (images below), I’ve updated the layout and MKI component table.  It clearly has 22n input and output caps, which is certainly a detour from the usual 10n in and 100n out.    
Despite the relatively small output cap, it still sounds fat.  22n and 33k = ~220hz roll-off as opposed to 100n and 47k coming in at ~34hz.  It starts with more bass input care of the 22n and a larger coupling cap on the second stage, so it has less to lose on the output.   I tried a 100n and it sounded too woolly in the low-end.
Worth noting that the 100n and 8.2k usually found before Q3 has a roll-off of ~194hz.  The larger 25u and 8.2k has a roll-off of less than 1hz.  So basically things even out somewhat by the time it reaches the level pot.  This does of course lead to a different tone, as all three transistors are receiving more bass in this version.   

CASTLEDINE MKI PHOTO CARE OF REVERB



note the 22n input & output caps

I believe the output resistor is 3m3 instead of 2m2 – maybe to trim some level off, as this doesn’t have a resistor across the 500k pot.


MKI VIDEO DEMOS




MODDED MKI TONE BENDER LAYOUT

I trimmed the layout down and spaced the components out, as I had a piece of vero this size to use and the one above is a little cramped.  


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