Nice bit of MKII history on fuzzboxes.org The MKII might be the most popular of the Tone Benders, although personally I'm split between the MKI & MKIII.
There's also this interesting timeline on the D*AM forum. Not sure who made it, but it's a handy reference (thanks ClassicFuzz).
TONE BENDER MKII COMPONENT VALUES TABLE
R7
Apparently, this resistor was used to shave a bit of gain off circuits that were prone to making unpleasant noises when Attack was set to full. It's said that this was only on some short board Solas, and some Marshall Suapfuzzes.
C6
My experience with this circuit is that if you don't have a cap on the power, it can oscillate/make terrible noises like hell.
LEAKAGE & HFE
A lot of talk about this - I'm not going to get into absolutes but keep in mind that these originally used quite leaky transistors and there are reports of nice sounding ones with very high hfe.
APPROXIMATE VOLTAGES
As the heading suggests - these are approximate voltages only. Results will vary from unit to unit, and if it sounds good to you, then don't stress about some numbers.
All voltages shown below are negative
Q1
C 8.5
B 0.3 to 0.06
E 0.0
Q2
C 0.13 to 0.32
B 0.07
E 0.0
Q3
C 7.5 to 8.5
B 0.13 to 0.22
E 0.1
-4.5 volts is not what you're after on Q3 collector - that's fuzz face territory.
Tuning tips by Dave Main - if you're using a trimmer in place of the 8k2 resistor.
You can also do it by ear, which is much more fun. Get the MKII running into a clean amp at a reasonable volume. Set the Level full and the Attack totally off. Roll your guitar's volume control back a wee bit, about 7-8 if you have a Strat. The tone here should be pretty clear and clean, if you can hear some fuzzy artefacts then inch the trimmer over to the left until they disperse. If you then crank the Attack and pull up your guitars volume you'll also have maximum sustain from the unit, that too should give a little play on any temperature fluctuations.
Hi! In the Sola Sound original version the transistors were mostly OC75 (just for a brief time they used the OC81D) this means R1 and R3 were 10k/47k.
ReplyDeleteIf you want you can add the very first versions of this circuit (named as short circuitboard, that were just MK1.5 with the additions to be a MKII. In this case they were the same as the Sola Sound but without C1, and at least in one pedal the 10k were 12k.
I'm working in one of this but a little souped-up (bigger output capacitor and a Bias external control for the spanish hot days)
Keep the amazing work!
Thanks Mister Hate - I’ve added that to the list. Appreciate the info.
DeleteOh and hope the souped up version goes well - I’m sure it will.
DeleteHi Andy! I plan to build one of each TB version, so this is useful info. Which do you think would be the closest to the one used by Jimmy Page?
ReplyDeleteI found a nice video playing with MKI.5 circuit, if you want to take a look at it: https://youtu.be/fdDEWTUDNRU
Hi Felipe - cool video. Thanks for sharing.
DeleteI’m not sure which one would be best for Jimmy Page. They’re all going to be pretty close, as the differences aren’t major.
I’m going to say not the Marshall, but that’s about it. Let me know how your builds turn out (please).
Andy
The main difference between the Fuzz Face and the MK1.5 is the voltage.
DeleteThe Fuzz Face was biased colder than the MK1.5 because the leakage of the NKT215 and the 33k. The bias of Q2 collector was between 3 volts and 6.5 volts. On the MK1.5, because the OC75 were pretty leaky transistors and the 47k to the collector of Q1C, were biased around 7.5v to 8v. For this reason Sola Sound added a booster before the circuit (the born of the MKII), because during the summer season with the leakage of the OC75, and the hot bias a lot of the pedals starts to cut the sound completely.
If we come back to the topic, the one Tone Bender that is known for sure that were used during a brief time for Jimmy Page is the Rotosound MkIII. In this lovely blog you will find a chart like this with the Rotosound variant. The MKII that was used by Jimmy Page is still a mistery...
Interesting Mister Hate. Did not know that about the evolution of the MK1.5 to the MKII.
DeleteThe video was cool, but the moment I saw they were using silicon transistors, I was a little thrown. I get why they did it, but still...
I have a few OC75s and they are pesky little beasts. Sound awesome when they work, frustrating when they don’t behave.
Silicon is no replacement for a 75.
In the last post where I wrote NKT215, I was trying to say NKT275.
ReplyDeleteI love the sound of OC75, but they only work in circuits that calls for leakage.
Q1 in Tone Bender MKI, Q1/Q3 in Tone Bender MKII and Q3 in Buzzaround/Tone Bender MKIII (I really love it in this circuit). Even as Q2 in circuits similar to Fuzz Face/MK1.5. But I had a hard time trying to make it work on Q1 (unless I use a much smaller Q1C resistor). I think this is why DAM makes a mod on the MK1.5 when he uses OC75 in the MK1.5 (https://stompboxes.co.uk/forum/viewtopic.php?p=235648#p235648)
All good - I knew what you meant.
DeleteI know right; OC75 in a MKIII is magic. A tad noisey a times, but it has something extra going on. I gave someone a few to try with different transistors and they were fixed on the 75. Had to have it.
It’s actually one of the few pedals where I can sit and test Q3 transistors and love nearly everyone I try for different reasons.
Thanks for the DAM link. Makes sense to do that.
Andy
Sure, right now I'm stacking up with some mojo parts 😄 I'll keep you updated. Cheers.
ReplyDeleteConcerning the Vox Tone Bender Professional MKII, I was just reading this on fuzzboxes.org:
ReplyDelete"Earlier examples were built with slightly larger value input & output capacitors; and the very last of the Vox MKII’s were built without an input capacitor at all."
https://fuzzboxes.org/voxtonebendermkii
What kind of effect has leaving out the input capacitor soundwise?
Hey there ClassicFuzz. I read the story and I was also a bit confused about the missing input cap. Then I read the comments. The cap that was removed was not the input coupling capacitor, it was the 10n cap to ground on the input.
DeleteThe input cap to ground only cuts high end. In the Vox Tone Bender MKII with 15nf input caps to ground, the fuzz has less top end than the Marshall Supa Fuzz (usually 10nf), this less top end than Sola Sound (usually 5nf) and this less than the original short board circuits that miss that cap.
ReplyDeleteIn any case, this cap appears and disappeared (or changed this value) along the production timeline and, probably, because of the stock Sola Sound had during the time of building specific issues.
This cap is C1 in the schematic above.
ReplyDeleteJust an idea, and please correct me if I am wrong: So basically I could build the SCB, Normal Sola Sound and Vox in one and just use two switches (1. Input cap Switch 3-Way DPDT (None-10n-15n) and 2. Output Cap Switch 2-Way DPDT (10n-15n)? Or would there be an easier way to do this?
ReplyDeleteHello
DeleteYes, you could add switches for caps. Maybe even a rotary switch to mix and match even more options.
Hey, I was wondering I currently scanning for different versions of the MKII and saw this post in the D*A*M Forum concerning the Macari Reissue. Apparently he does not always use 15n for C1 and C5. Why would he switch between these capacitors for the regular MKII?
ReplyDeleteThe 15nf in C1 and C5 were find in the Vox Tone Bender MKII, but not always. This version has more low end (C5) and dump more high end to ground (C1). But the changes in production were usual yesteryear, depending on availability, probably.
DeleteHard to say - he may have just felt like it, as 10n and 15n were both seen in vintage pedals. Maybe a personal preference? They both sound good.
DeleteForgot to post the link: D*A*M/Sola Sound Professional MKII
ReplyDeleteDid we already tallk about this version?
ReplyDeletehttps://reverb.com/de/item/74372013-sola-sound-tone-bender-mkii-trojan-horse-led-zep-edition?show_sold=true
Apparently this so-called "Tojan Horse" is based on Jimmy Page's Tone Bender MKII. Are the values any different? 10n Input and Output Cap.
It looks fairly normal. I think there’s an electrolytic input cap hiding under Q1 on the left hand side.
DeleteAnd no, had not looked at this one before. Thank you for pointing it out. I’ll have a closer look.
…and this is what it sounds like: https://www.youtube.com/watch?v=dHAzMw_XzGg
Delete…and more gutshots: https://www.guitarscanada.com/threads/d-a-m-sola-sound-mkii-professional-trojan-horse.295388/
Delete…and more: https://scontent.cdninstagram.com/v/t51.2885-15/281554305_522318442931698_8322857976835839770_n.webp?stp=dst-jpg_e35_p640x640_sh0.08&_nc_ht=scontent.cdninstagram.com&_nc_cat=110&_nc_ohc=0v2DrMQK4bAAX8IU69e&edm=APs17CUBAAAA&ccb=7-5&oh=00_AfCiwVJVjifXRhMcMDv1AVO8T8_u5UDv9ZX2o00Q9F2mDQ&oe=653C3445&_nc_sid=10d13b
DeleteRegarding R7, did you ever come across this timeline in the D*A*M forum: https://stompboxes.co.uk/forum/download/file.php?id=7096
ReplyDeleteHello - No I had not. Thank you for sharing.
Delete