JHS - Treble Booster ( Hornby-Skewes )

[Professor SourTone]

http://cgi.ebay.co.uk/John-Hornby-Skewe ... dZViewItem

[analogguru]

That´s a "fake" - the real thing didn´t have 10µF coupling caps:



with 10µF it would be a booster, but not a treble booster.

analogguru

[Professor SourTone]

To be fair he does decribe it as having a more full range effect than just a treble boost. I've never seen one before.

[analogguru]

Here are full size pictures of the first unit (owner is/was "Cozzigreen"):
http://i269.photobucket.com/albums/jj52 ... s/JHS5.jpg

JHS5.jpg

Here you can see the original capacitor in blue:
http://i269.photobucket.com/albums/jj52 ... TBGuts.jpg

HSTBGuts.jpg

then replaced:
http://i269.photobucket.com/albums/jj52 ... SGuts3.jpg

JHSGuts3.jpg

The funniest thing can be found in this article too:
http://www.geofex.com/Article_Folders/z ... onkbst.pdf
where the treble booster is based on this - totally wrong - schematic:
http://www.diystompboxes.com/pedals/schems/HS/HS.gif

HS.gif

which was traced from this picture:
http://www.diystompboxes.com/pedals/schems/HS/HS2.jpg

HS2.jpg

without ANY coupling caps because somebody took them out.

The result is/was wild speculations about the function of this circuit instead of a little bit critical thinking. Sorry, but no technician would bias a FET with 62k/10k.

Ammscray who traced the circuit even misread the 2N 4061 which can be seen here:
http://i269.photobucket.com/albums/jj52 ... sistor.jpg

JHSTransistor.jpg

and here:
http://i139.photobucket.com/albums/q312 ... tranny.jpg

tb_tranny.jpg

as 2N 4861 and for this reason assumed that it would be a FET.

Anyway, here is a schematic which is closer, even when I doubt the 1n at the input - maybe it is 10nF

http://i139.photobucket.com/albums/q312 ... 2N4061.gif

analogguru

[JHS]

JHS built at least 2 different versions of this Booster, one for the use with the Zonk-Machine and the other as a standalone TB. The standalone version has an output cap, the other doesn't.

As far as I know the first bunch JHS TBs have PNP Ge-trannies and are similar to a RM.

JHS

[analogguru]

JHS built at least 2 different versions of this Booster, one for the use with the Zonk-Machine and the other as a standalone TB. The standalone version has an output cap, the other doesn't.

This are rumours and it is pure nonsense.

As you can see here:
http://i139.photobucket.com/albums/q312 ... 571d_1.jpg
http://i139.photobucket.com/albums/q312 ... 54f4_1.jpg
http://i139.photobucket.com/albums/q312 ... 50ac_1.jpg
http://i139.photobucket.com/albums/q312 ... sb_2_a.jpg
http://i139.photobucket.com/albums/q312 ... sb_2_b.jpg

was the Treble Booster also part of the SHATTERBOX but not of the Zonk-Machine. Even in the Shatterbox were the coupling caps as you can see.

As far as I know the first bunch JHS TBs have PNP Ge-trannies and are similar to a RM.

The only unit rumoured to have ge-pnp and supposed to be the blackmore-boost looked like this:
http://i27.photobucket.com/albums/c162/ ... 1186_2.jpg

analogguru

[MoreCowbell]

Anyway, here is a schematic which is closer, even when I doubt the 1n at the input - maybe it is 10nF

http://i139.photobucket.com/albums/q312 ... 2N4061.gif

analogguru

10n would make more sense given the description of the "sound" of the HS. 1n would be incredibly bright, like the Electro Harmonix Screaming Bird

Theres almost as much disinformation about this circuit as the CJOD.

[JJabaman]

So is this a working schematic for the "original" Hornby Skewes TB?

http://i139.photobucket.com/albums/q312 ... 2N4061.gif

Anybody know the "mods" to the Blackmore HS?

[Solidhex]

Yo

Has anyone confirmed the input/output cap values for this? It drives me crazy how every picture you see is always at the wrong angle!

--Brad

[Electric Warrior]

Yo

Has anyone confirmed the input/output cap values for this? It drives me crazy how every picture you see is always at the wrong angle!

--Brad

22n in, 1000p out, if the HS Treble Booster is identical to the Highfield unit pictured in this thread: http://www.vintageamps.com/plexiboard/v ... =6&t=80259 (he got it wrong in the schematic..)

the shatterbox we traced over at the D*A*M forum has a 10n at the booster's input: http://stompboxes.co.uk/forum/viewtopic ... 1&start=40

[Electric Warrior]

when it uses the same enclosure and circuit board it's more than just a "clone".

[Solidhex]

Yo

Ugh. .001 cap? For input or output it sounds like a bummer.

--Brad

[Electric Warrior]

there's another one with a .001 at the output on this thread: http://dawkmods.proboards34.com/index.c ... 696&page=1
the input cap is harder to read..

[Electric Warrior]

Same enclosure and circuit board means it's right?
So,if I took a ferrari shaped body,and a ferrari shape chassis,and built it up from what people who had never seen one told me,I'd have a ferrari?
The enclosure is just a bloody box,man
"and same circuit board",how do you know?
Some guy builds it,and says,"built from the original circuit",and you then say to me,"it must be right,it's the original circuit" (sic)

what makes you think the highfield unit is a fake?
it's only a small part in the puzzle, but I think it fits right in.

and please stop quoting me wrong.

There are many views on the correct circuit,so logically,most must be wrong
Also looking at photos taken at stange angles,to ascertain component values,seems to me an exercise in futility
AG said the fet had been read wrong,it was really a 2N4061. How often do you think this happens?
In the British pedal industry of the 60's&70's, they used whatever components would work that were at hand,other countrys i don't know

I KNOW that part numbers have been read wrong in the past. And I also KNOW that some part values varied. that's exactly why I gather information from photos and don't want to rely on schematics.

[PurplePeopleEater]

Same enclosure and circuit board means it's right?
So,if I took a ferrari shaped body,and a ferrari shape chassis,and built it up from what people who had never seen one told me,I'd have a ferrari?
The enclosure is just a bloody box,man
"and same circuit board",how do you know?
Some guy builds it,and says,"built from the original circuit",and you then say to me,"it must be right,it's the original circuit"
There are many views on the correct circuit,so logically,most must be wrong
Also looking at photos taken at stange angles,to ascertain component values,seems to me an exercise in futility
AG said the fet had been read wrong,it was really a 2N4061. How often do you think this happens?
In the British pedal industry of the 60's&70's, they used whatever components would work that were at hand,other countrys i don't know
Much better is to start with a pedal 'everyone' is ok with,like a rangemaster,and tweak it till your ears are happy with the result
Build others of course,but getting hung up over a cap,when you don't have a mint example to check from,is anorak behaviour
Like train-spotting

Here is a composite of boards from pictures linked in this thread to help suss things out. Clicking on the attachment will show it full size.

Compare to this picture of the Highfield : http://farm4.static.flickr.com/3076/311 ... 44.jpg?v=0
You can find an enlargement of that photo here: http://img.villagephotos.com/p/2008-12/1329951/hf.JPG

Keep in mind that the Highfield is less likely a clone of the HS than it is a "rebranded" unit actually manufactured by HS, as was common practice during the era. See Vox, Colorsound, Arbiter, etc for other companies that built units and sold them for rebranding.

[Electric Warrior]

another clue for a .022 input cap: http://www.diystompboxes.com/smfforum/i ... #msg338505

I suspect somebody misidentified the in- and output caps again...
that would make the output cap a 1000pf - again. so it seems to have been very consistent. it's also in the highfield, the vero board shatterbox, a pcb shatterbox I've got a picture of and the hornby skewes treble booster with the small, grey caps.

[Electric Warrior]

another clue for a .022 input cap: http://www.diystompboxes.com/smfforum/i ... #msg338505

the picture that analogguru posted is from the very same auction, btw

[Electric Warrior]

found the source of the highfield pics: http://www.bossarea.com/forum/topic.asp?TOPIC_ID=5903

[Solidhex]

Yo

I just did some breadboarding with a TI 2n4061. Swapped .001uf and .022uf caps as the ins and outs. With the .001 as the input it just basically cuts the bass out. No real "boost" to speak of. Maybe some very slight distortion. The other way around with the .022 as the input you get more of a throaty cocked wah style treble boost as you would expect. The 100k pull down saps a fair amount of gain on the way out.

--Brad

[PurplePeopleEater]

But really,british pedal builders would use whatever did the job,not what was 'correct'
Back then,components were not always available,which to me,makes researching an input caps value an exercise in futility
Best to worry about how to make it work the way you want
Start with what's accepted,then explore...

I disagree. It certainly isn't an "exercise in futility" as you say. No manufacturer WANTS to use substitute parts, they always start with a "standard". The JHS Treble Booster certainly had a "standard version" that they started with, and occasionally had to make part subs depending on what was available. All people here are doing is trying to discern what the standard version is, from the available photos and information.
EH used lots of substitute parts throughout their early years, yet we still want to have a definitive triangle BM schematic. Different part values were used here and there, and even different transistors. However, EH certainly had a "standard" for the values, and that is what we are going for here. If people didn't look for information on the "standard version", then we wouldn't have accurate schematics for any of the early BMs, a lot of Colorsound products, etc. - we would simply have schematics that said "this is close enough".