Sola Sound - Tone Bender Mark I (1965)  [schematic]

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

I had a closer look today at the guts mentioned in the above links and I have to say that at least all ungooped Hurst Tonebender-RI shown (stripboard or etched board), are exact copies of the Tonebender Professional Mk II - with AC12x or NKTxxx transistors.

IMHO it´s a little bit questionable to put this circuit in a different case similar to the Tonebender MkI.

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Post by JHS »

IMHO Hurst built a Mk1.5 RI because it's nearly impossible to get those TI C381 trannies (didn't found any info on the web) but trannies for the 1.5 are still available.

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Post by analogguru »

IMHO Hurst built a Mk1.5 RI...
Sorry, but the Mk1.5 uses only two transistors: OC 75 (which are still available on ebay). Also the Mk 1.5 has 47k as collector-resistor for the first trannie of the fuzz-circuit. Hurst uses 100k, as in the MkII.

As you can see in the guts there are three transistors in the Hurst-RI and I did a trace - not only a quick look - and came to the conclusion that what I saw is identical to a Pro MkII - except the transistors.

If you don´t believe it, you can verify it by tracing it for yourself.

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Post by JHS »

Right you are. It's a MkII.

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Post by Torchy »

I fail to see how Jimminy Hendrix could of used a FF, when Zvex didnt invent it until, like, a couple years ago. :roll:

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Post by vanessa »

Torchy wrote:I fail to see how Jimminy Hendrix could of used a FF, when Zvex didnt invent it until, like, a couple years ago. :roll:
As you can clearly see here he's using a Analogman NKT-275, that predates ZVex's Fuzz Factory at least by a few years. :lol:



Image

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Post by Torchy »

Dammit, pwned again.

I'm sure I've seen those wah-wah boots on though.

Good god, that Jimminy bloke's here as well ...

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Post by vanessa »

Yes and what most people "in the know" have come to realize is that Jimi's tone actually comes from those boots (see photo).

It was in later years, after his wah-wah boots were stolen backstage at a gig in Manchester (which caused him to cancel his appearance at Altamont, opening for the Rolling Stones), that his tone suffered, ultimately causing him to spiral down from there until his death in 1970.
A sad but true story that parallels such greats as John "Stumpy" Pepys who died in 1969 in a bizarre gardening accident or Eric Childs who died in 1974, choking to death on someone else's vomit.

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Post by analogguru »

Yes and what most people "in the know" have come to realize is that Jimi's tone actually comes from those boots (see photo).

It was in later years, after his wah-wah boots were stolen.....
...and from there on his sound could be described more as "stink-foot-wah"-sound, that some ingenious guys at Electro-Harmonix developed the "Hotfoot-Wah" to overcome this problem..... :lol: :lol: :lol:

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Post by $uperpuma »

I've breadboarded a MKI from the mains schematic... and after a few trannies tried, I have an approximation of the sound I hear in 1966 Jeff Beck Yardbirds stuff. Has anyone recorded clips of this that I can compare to?

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Post by frank.clarke »

On the subject of the MkI, I give up on trying to make it sound good. I'm going to change the Q1 buffer to a Q1 gain stage with a gain control on Q1. Plus, the MkII has way too much gain for me, I have a 1k base-emitter resistor on Q1 to cool it down, with the "Silicon" gain mods for the Fuzz Face section. I assume the TBII was a way of using up low gain transistors.
Plus Jeff Beck, when he went on Cherry Blossom polish in the '80s his tone went down the drain, but I here he's back on the Kiwi and Nam-era paracord laces.

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Post by vanessa »

frank.clarke wrote:On the subject of the MkI, I give up on trying to make it sound good. I'm going to change the Q1 buffer to a Q1 gain stage with a gain control on Q1. Plus, the MkII has way too much gain for me, I have a 1k base-emitter resistor on Q1 to cool it down, with the "Silicon" gain mods for the Fuzz Face section. I assume the TBII was a way of using up low gain transistors.
Plus Jeff Beck, when he went on Cherry Blossom polish in the '80s his tone went down the drain, but I here he's back on the Kiwi and Nam-era paracord laces.
I don't have the info in front of me but if you set it up with hfe's like others have set up the Fuzztone you'll get it to work fine. It's sort of a pain to find the various hfe's that it needs. It also requires a certain amount of leakage to get it to bias right for "that tone". So if you threw all those crappy ge transistors away that you sorted for your killer fuzz face you'll be smacking yourself in the head because those are the ones that make this thing tick.

[smilie=a_doh.gif]

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Post by frank.clarke »

Thanks Vanessa, mine goes from pleasant overdrive to Foxx Tone Machine depending on the transistors. It sounds exactly unlike something Mick Ronson would have used. I'll give the AC128s that just arrived a shot and that's it, so under the knife it goes.

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Post by vanessa »

frank.clarke wrote:Thanks Vanessa, mine goes from pleasant overdrive to Foxx Tone Machine depending on the transistors. It sounds exactly unlike something Mick Ronson would have used. I'll give the AC128s that just arrived a shot and that's it, so under the knife it goes.
I would not waste those on this one. You have to step back... This one is not a top shelf project by any means. Buy up some 2n404's cheap, the crappier the better. :wink:

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Post by frank.clarke »

OK, I can get a pretty good Led Zep BBC sessions tone now (NTE102A as Q2) so that will do, I'll box it up tomorrow. Q3 needs to be very low gain, Q2 collector resistance gets low and pulls the battery voltage down.
Gary Hurst said he got 20 seconds of sustain on the prototype (on an Italian website), that isn't the vibe I get. Mind you, it is very loud, so maybe the amp is supposed to contribute. Enough for tonight!

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Post by modman »

I split the topic keep discussion here on builds based on vanessa's mk I schematic above

Mark II experiences here
http://freestompboxes.org/viewtopic.php?t=920

Frank, really want to hear those clips! any chance?
Please, support freestompboxes.org on Patreon for just 1 pcb per year! Or donate directly through PayPal

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Post by DougH »

Re. the MarkII and hfe: I built a Si MarkII with 2n5089's (hfe 700+ (!)) and it sounds great! I added a tone control to it, but otherwise its pretty similar to the MkII. Very smooth fuzz and one of my favorites. I wonder if there is some issue other than hfe involved here?

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Post by vanessa »

frank.clarke wrote:It sounds exactly unlike something Mick Ronson would have used.
If you're talking about the MK I, I hear there was a transitional period between the early MK I circuit and the MK I.5 (the one with two transistors). I hear there's been some original MK I boxes found with MK I.5 guts in them and I think Mick Ronson's might have been one of these (just a hunch).
Try building a MK I.5 and put a wah-wah half cocked in front of it (not after). I think you'll hear what I'm talking about.

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Post by BIGSMITTY »

awesome! ive been looking for mkI schematic for awhile now i just need to find the transistors. will same ones for mkII circuit work? vanessa your the best.

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Post by frank.clarke »

BIGSMITTY wrote:awesome! ive been looking for mkI schematic for awhile now i just need to find the transistors. will same ones for mkII circuit work? vanessa your the best.
Apparently not. Give us your tired, your poor, your leaky. I mean, they work, but it sounds too distorted. I don't know what the original sounded like, so who knows. I ended up with this: http://www.guitar-pedals-effects.com/Toneblender.html 'cos I don't like the input buffer.

edit to fix link which was broken by a comma
Last edited by frank.clarke on 20 Dec 2007, 19:30, edited 1 time in total.

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