JHS - Treble Booster ( Hornby-Skewes )

Discussion regarding early stompbox technology: 1960-1975 Please keep discussion focused and contribute what info you have...
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Electric Warrior
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Post by Electric Warrior »

Great new gut shots on Graham's site: http://decadeoffuzz.com/index.php?/proj ... es-pedals/
Another confirmation for the .022µF in/.001µF out proposition. :mrgreen:

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Post by Electric Warrior »

Turned out the Shatterboxes with Mustard caps have the 0.022µF cap at the booster's input as well. I've been told those had a 0.01µF cap, like the Vero board Shatterbox we traced. So it wasn't a different spec. Just the usual input cap inconsistency. I guess they increased the size of the input cap over the years, but I would need much more data to confirm that.

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Post by DougH »

I breadboarded the JHS treble booster tonight with .022u and .001u output caps. Ran my strat through it into my "Marshall" and it did sound pretty "Blackmore-ish". Nice sound and a lot of gain. Only thing is it really cuts the bass. Rangemaster does too so I will have to compare. I used an AC188 I had lying around- collector voltage was -5.3v. Not exactly the same but close. Nice thread. It's time we got to the bottom of this one. :wink:
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Post by DougH »

Okay, funny... For some reason I thought the 2n4061 was a Ge PNP, but it is actually just a general purpose Si PNP. Hmm... I wonder how a simple everyday 2n3906 might sound in this...
"You have just tubescreamered or fuzzfaced yourself " -polarbearfx

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Post by Electric Warrior »

Give 'em a try :)
I've tried two different kinds of TI 2N4061 in my Shatterbox so far. One type seems to have sweet midrange honk, while the other is kinda harsh sounding with more treble and less honk. HFE's were roughly the same. The trebly ones all measure between 95 and 120, while the honky ones cover a much wider range (up to 230). The honk always comes through, no matter what HFEs I select.

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Post by DougH »

OK, played with it again last night. .022u on input is way too thin for me, but I'm liking a 1uf film cap right now. 1000p on output sounds good because it is still a treble booster. Higher value output caps make it sound too fat and the bass gets flubby, more like a fuzz. 10uf in/out sounds ridiculous to me, unless you just want a fuzz box sound. I tried a 2n5089 Si and AC188 Ge. Both sound good, the Si has slightly more high freq response- can't go wrong either way.

Today I'm going to try some NPN's and a neg ground circuit. Seems that the key to this thing, for me anyway, is to keep the input cap pretty high to get full freq response through the gain stage. This creates more harmonics and distortion- then keep the output cap thin (1000p sounds good to me). But I'm looking for a "Blackmore" sound with my strat through my cranked "marshall". I don't care about fuzz box sounds- I've got plenty of those already, or building yet-another-rangemaster- already have one. I want something more unique for the strat and don't care if it works with humbuckers.
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Post by DougH »

BTW, I think it's kind of useless to agonize over these coupling caps and which are "correct". From all the photos it looks like these were all over the map. Tweak them the way you like and leave it alone. That's my diy credo anyway...
"You have just tubescreamered or fuzzfaced yourself " -polarbearfx

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Post by phibes »

I've always overlooked this circuit. Is it worth building up?
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Post by phibes »

I'll have to dig through the thread later tonight. Anyone confirm any schematics? I'm just scanning through right now and there's a lot of talk.
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Post by Electric Warrior »

biffa wrote:For sure!
It's not the most powerful booster,or feature packed,but it does its job in a very natural way
Its 'raison d'etre' tho',is to feed a zonk
They say put the booster after,but you'll get no 'swell' on the vol. that way,and booster first will emphaslze the octave-up element of the zonk
Put a 100k pot pulldown on the output,,u have the 'blackmore mod'(smoothed out his treble/mid tone a bit)
He also used an aiwa reel-reel tape recorders pre-amp
Oh, you need to put the booster in front of the Zonk for the octave up thing?
My effort sounds nothing like yours. It's more or less exactly like the first T.Rex album. Shitty and radical, but it kinda works in the right context.

I've tried the 3k9 in parallel with the Fuzz pot today. It fixes most noise issues, but it causes some severe gating when used with humbuckers (but that's no big deal, reducing the volume helps).

btw, do we need a dedicated Shatterbox thread or should we discuss this on the Zonk II thread? The Zonk II thread seems to be mostly about the Zonk I..
phibes wrote:I'll have to dig through the thread later tonight. Anyone confirm any schematics? I'm just scanning through right now and there's a lot of talk.
Confirmed and working schematic on page 3 :wink:

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Post by phibes »

I'm assuming the one you drew? :hmmm:
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Post by Electric Warrior »

yeah :mrgreen:

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Post by DougH »

OK, for a standalone booster for strat->marshall I'm really liking 1u in, 1n out, and a PNP 2n5087. This one is getting built like this.
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Post by Electric Warrior »

1u in :?: sounds kinda large to me..

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Post by DougH »

Gives it a good amount of distortion/harmonics. The 1n keeps it from getting blatty.
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Post by DougH »

Well, after messing with it some more I'm starting to think "full range" works better for me than "treble boost" with this thing. I've got .022u's on the input and output and they sound pretty good right now. Works with the guitar vol better and gives the strat neck pup a much "rounder" sound, which is one thing I'm after with this.

Heh-heh, darn pedals... Drive me nuts sometimes...
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Post by bobster »

they do indeed drive ya crazee!
ive tried all sorts of combos 2 x 10uf , 2x 0.1uf , 0.022 in 0.010 out.
current one which is showing some promise and sounded good on weekends gigs is 10uf in , 5n out.
maybe not so good at full setiing but wound back just a little was very pleasing

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Post by DougH »

Well, mine's back to the AC188 Ge transistor and .047 in and out. I like this sound a lot. I think I'm going to build it like this.

Here's an interesting site on Ritchie Blackmore's gear btw. I don't know how factual this stuff is, and it's obviously a thinly-veiled marketing page for BSM, but it is interesting nonetheless:

http://www.treblebooster.net/blackmore.html
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Post by DougH »

FWIW I finished this thing today, finally. .047 in, .022 out, 5K pot in place of 3.9k Rc for a "gain" control, 68k in place of 62k, 100k shunt on out, 10M shunt on input (to eliminate "switch click"). I just put it in a box in place of my old rangemaster (still have the newer one). Does it sound like Ritchie Blackmore? I don't know... I love it with my strat though- much more than the rangemaster (which IMO works better with humbuckers). With the hardtail strat vol on 8.5-9 it sounds pretty close. With it on max it's a little heavier than most Blackmore, but sounds great and has a lot of sustain. Cool circuit!
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