The Yardbox™. A faithful sonic copy of the original Sola Sound Tonebender, purportedly the only distortion pedal used on Led Zeppelin's first two albums. The pedal has no similarity to Jumbo, Supa, or the Vox Tonebender. Wide variation in tone and smooth dynamics at all volumes.
Ohh more reason to germanium it up!... can I use an other diodes in place of the 1N270?
ReplyDeleteHave you got any other germanium, 1N34A maybe? If not a Schottky diode will have a similar voltage drop, or a silicon will work fine in there, it will just change the fuzz character somewhat. It's all to taste mate, socket and use what you like best.
DeleteAlso, all the pots are linear? just thought I'd make sure as you've labelled them in pairs
DeleteYes I have 1N34A's.. I try them in it, Cheers mate.
DeleteYes all linear, and only mentioned in pairs because two + two use pots of the same value.
DeleteI'll have a crack at this tomorrow. As the tonebender MkII was a hit I can see this one being a keeper too.
Delete.Any transistor recommendations? ill probably have to source from mammoth electronics to keep multisource shipping down. They are pretty expensive and I don't have any on hand
ReplyDeleteA Tonebender measured set would be a good choice. The part number isn't as important as the gain and leakage.
Deleteunsolicited plug for Guitar PCB and Small Bear both measure and matech pairs and sets, specifically for Rangemaster, FF and TB. Both US unfortunately.
DeleteYes if you don't have your own stash it's much better to get a matched set. You could buy 20 from some random eBay seller and struggle to get a set if the quality wasn't very good, so it's worth it for the peace of mind that what you'll be getting will be useable.
DeleteFrom where I sit, you can call this one verified. What a sweet little circuit. I did take the liberty of adding column 11 (15 total) so that Q2 was a three pin SIP socket. I am using three 2N404a's, 93/0, 122/.04 and 130/.06 (hFE/mA)leakage. WOW!
ReplyDeleteExcellent thanks for verifying Pete, and yes I'd probably make it 15 columns too.
DeleteBeing very similar to your Soulbender´s layout, i think that i´ll put some extra sockets and experiment... why not?
ReplyDeletePlus some of that "secret countermeasures" to help with the temperature issue ;)
Mark, thanks again for this layout, sure it can be found everywhere on the net, but your designs plus the constant participation of the other builders are very encouraging for me!
Do you think a bias trimmer could be useful in any way, Mark?
ReplyDeleteIn case, the way should be to replace the 18K resistor on Q3 collector with a 50K trimmer, isn't that? I'm asking just because I can see a singular biasing system on the Soulbender's schematic, and so... :)
That would be the logical choice in my mind, although the Soulbender omits the 10K collector to ground resistor completely and biases with a 500K trimmer and 10K resistor in series from collector to base. I'd go with the 18K with this I think, there's no point in modding it into a Soulbender.
DeleteJust a quick heads up, the Soulbender biases to the sweet spot fairly high up that 500k trimmer, I don't know if that would make any difference to this layout, as Mark said it's baised differently, but I just thought I'd let you know in case you weren't getting any joy with the 50k trimmer. To be honest it still sounded pretty sweet even without being biased correctly so I'm sure you'll like the sound of this one too!
DeleteThe trannies has finally arrived, (OC77, OC76 and OC75 with hfe 113, 81 and 73 respectively) smallbear has even included the Ge diode (leakage-matched?) with the set... a very nice bonus. I´ve built it without any bias mods (I´ve just omitted the two volume thing, as its seems to be useless... just connect tone 2 to volume 2 and be happy) and, maybe thanks to the matched set, it sounded very good with the stock bias values, no gated sounds, nice sustain, nice decay and the overall character is very like the Tonebenders demos on the net... its just have more gain that i´ve spected... maybe i´ll put a pre-gain control and a pre-filter to cut some lows for more clarity with humbuckers.
DeleteI'm not used to these -9v circuits, do I have to reverse the polarity of the battery, that is connecting the battery - to the -9v and the battery + to the input jack sleeve ?
ReplyDeleteYes, connect battery -ve to the -9V connection, battery +ve to the +ve ground connection(s).
DeleteThank you Mark
DeleteWould it be possible to have in the offboard section a layout showing how to wire these >0 ground fx, including battery, 3pdt and dc jack ?
Actually I'm gonna post that in the request section
Cheers
Denis
This is a very useful layout for experimenting with 3 knob Tonebender variants. The original had a 220k resistor from the tone pot to the volume control and the "Prescription Electronics Yardbox" basically replaces that resistor with a pot and calls it a "Gain" control and has a couple of minor value changes. I did away with both and upped the value of the Volume pot to 500k Log and connected pin three direct to pin 2 on the tone pot. Works fine.
ReplyDeleteI socketed the three transistors and the diode. I tried 3 x 2n4044s, 2 x 2n3906 for q1 and q2 (silicon pnp) plus a 2n404 for Q3 and finally 3 x AC128. The gains of the germies were 60/70, 70/8 and 115/120. The 3 x 2n404 gave most volume but was a tad brittle a bit like a russian trannie. The 2n3906 experiment did not really work with the existing biasing and since I did not socket the darlington resistors I did not pursue it further. Basicially it gave a very quiet impression of a Zvex or Devi ~Ever effect i.e very gated. Some might like it - a bit. The 3 x AC128 version was by far the best. I played with that one so long if I had a dog my dinner would have been in it! As to the diode I was surprised to find that it is actually necessary and not some germie stabilisation/ lightning strike protection or whatever. Without it we are back in very gated effect country although not as bad as with the 2n3906's. I didn't have a 1n270 so I tried BAT85 - shottky with low forward voltage, an 1n34a the usual suspect and an 1n60P - a poor mans 1n34a. The 1n60P was the winner. The BAT85 was too harsh and gatey, the 1n34a was OK until I tried the 1n60p which seemed clearer. I suspect that the specified diode is probably better; either that or an OA91 perhaps? But as I said at the beginning this layout is ideal for experimenting with. Fun fuzz!
I didn't box this one yet because I also find it to be very gated
Deletejust built it last night and mine doesn't sound gated. it sounds great. BTW, I also saw a schematic of it that use B250K pots for the gain, fuzz and volume controls instead of B100K's ( http://www.turretboard.org/wp-content/uploads/2011/09/Yard-Box.pdf), while another shows B250K's for the gain and fuzz and B100K's for the tone and volume: http://fuzzcentral.ssguitar.com/3knob.php.
ReplyDeletewhat's up with that?
BTW, if you're getting too gated of a fuzz from building this one, you might try replacing the 18K resistor with a 50 or 100K trimpot. you should be able to dial it out so it has a much smoother decay. I also replaced the top left 10K resistor on mine with a 20K trimpot so I could control and tune the bias at the collectors of Q1 & Q2.
ReplyDeletejust made it with some toshiba germs and a 1n34a sounds sweet!
ReplyDeleteI made this with transistor i took out of an old transistor radio. I didn't measure them or anything. I looked up the average hfe on the internet and put them in the right places. I think toshibas are supposed to be good low leakage. I also cup the 1n34a out of the same radio.
ReplyDeleteThis is one of the best sounding fuzzes I have built to date. So far I have only tried high gain and leakage AC125s - but it sounds really good.
ReplyDelete