Soul Sonic - Folk Driver, The Honey Bee Challenge!

earthtonesaudio · Post by **earthtonesaudio** » 27 Apr 2009, 11:52

Using 2n5089 might solve the problem, but it might not. The collector-base feedback bias used in this circuit is hFE dependent, so while the 5089 will get you a little closer, it might not bias up "perfectly" without making some (either collector or C-B feedback or both) resistors into trimpots.

Hearing sound with no battery means you were running off the capacitors. You can't replicate that exactly with just a pot, but you can get a similar sound.

earthtonesaudio · Post by **earthtonesaudio** » 27 Apr 2009, 16:10

Don't know what the collector voltages "should" be, but the emitter voltage on Q2 should not be zero. Maybe you've shorted R7.

soulsonic · Post by **soulsonic** » 27 Apr 2009, 22:15

490 Hfe is probably too low. This circuit wants high gain transistors - something in the 700 to 1000 range should be fine. If you use transistors in that range, everything should work as intended. I've done them with random transistors, not tested or anything, and the results were consistent.
MPSA18 would probably be an excellent substitute.

There shouldn't be any need for adjusting or trimming or any of that. The 1M feedback resistors between base and collector do the biasing. High gain transistors are crucial because of the high amounts of feedback used.

Whoismarykelly · Post by **Whoismarykelly** » 30 Apr 2009, 06:18

Built one up with MPSA18s and this pedal is the very definition of low gain. I'll need to crank it and my amp up a bit in the morning to see whats what with some air moving. At bedroom volumes with the timbre maxed on the bass side it gets a very very mild overdrive / smooth lightly clipped clean boost sound. I like the way the highs are a little tamed. Its an overall more neutral tone than the Honeybee is. The HB has a pretty strong midrange emphasis and a real focused sound with the gain up a bit. The Folk Driver seems a bit flatter across the frequencies and more transparent (what an icky cliche tone word, sorry). I need to see if it stacks like the Honeybee since thats what everyone raves about. I will say that Im impressed that you've got a circuit with two really high gain transistors and four diodes and almost zero clipping. Plenty of volume though

soulsonic · Post by **soulsonic** » 30 Apr 2009, 09:59

Looks nice!
I got some cool results by stacking the Folk Driver with the Honey Bee... got a cool overdrive/distortion thing happening...
Yes, there's very little clipping... it's all about the feedback! This should be considered a lesson in how feedback can be used in cool ways. It is very neutral... I tried to "clean up" some things that sorta bothered me about the HB, but still have the basic gist of it.
What kind of pickups did you try it with? I tested mine with high-output humbuckers and it got some noticeable overdrive when maxed, but it may almost be too clean with low-output pickups. I tried to give it a gain range somewhat similar to what you get on the HB, minus the low-end splat crap that happens when the Nature is all the way down.

Personally, I don't really like having the HB at the end of the chain because it's volume is so limited... when used after a Klon, you can get a great heavy drive out of it, but you lose alot of the volume that you get from the Klon. It just sort of clamps everything down... it bothered me especially because I got a cool thing happening with just the Klon for rhythm and then kick on the HB for leads, but there was a big volume drop when the HB was turned on, even with it's volume up at max. In fact, I pretty much find myself running the volume on the HB on max all the time.
I made a point of making sure the Folk Driver has plenty of volume on tap. I think low gain overdrives work great as solo boosts, and a boost should have lots of available volume.

Whoismarykelly · Post by **Whoismarykelly** » 30 Apr 2009, 18:03

soulsonic wrote:Looks nice!
I got some cool results by stacking the Folk Driver with the Honey Bee... got a cool overdrive/distortion thing happening...
Yes, there's very little clipping... it's all about the feedback! This should be considered a lesson in how feedback can be used in cool ways. It is very neutral... I tried to "clean up" some things that sorta bothered me about the HB, but still have the basic gist of it.
What kind of pickups did you try it with? I tested mine with high-output humbuckers and it got some noticeable overdrive when maxed, but it may almost be too clean with low-output pickups. I tried to give it a gain range somewhat similar to what you get on the HB, minus the low-end splat crap that happens when the Nature is all the way down.

Personally, I don't really like having the HB at the end of the chain because it's volume is so limited... when used after a Klon, you can get a great heavy drive out of it, but you lose alot of the volume that you get from the Klon. It just sort of clamps everything down... it bothered me especially because I got a cool thing happening with just the Klon for rhythm and then kick on the HB for leads, but there was a big volume drop when the HB was turned on, even with it's volume up at max. In fact, I pretty much find myself running the volume on the HB on max all the time.
I made a point of making sure the Folk Driver has plenty of volume on tap. I think low gain overdrives work great as solo boosts, and a boost should have lots of available volume.

I always run my honeybree pretty early in the chain but I've been using a 386 drive more and more lately for low gain tones so its been sitting in the pile of pedals for a few weeks. I usually stack it into things rather than after them but stacking does weird things so it all depends. Im using an esquire with a barden danny gatton which isn't a screamer but it is a humbucker and has a reasonable amount of output. I have to check it out at full volume for a bit but when I was really digging in I was getting some grind last night. The Honey Bee is dynamic but I think you have to puch the folk driver a bit more to really pull out the overdrive.

Whoismarykelly · Post by **Whoismarykelly** » 30 Apr 2009, 18:34

I got everything really cooking and this pedal really does behave like the honey bee with other pedals. It stacks into things well without adding too much flub or compression. Into a 386 distortion it sounds really warm and fat with good midrange but not a huge congested hump. On its own into a loud clean amp its very responsive and can go from clean to a little bit of rock grind just by really hitting the strings hard. Im using it with the volume around 2:00 and the timbre at about 4:00.

soulsonic · Post by **soulsonic** » 01 May 2009, 05:24

Great Success!

I have to get another one built now to send to Donner so he can pass it around. Looks like it will be a popular build... I need to get the kit thing together, and I'll probably have to start building them for people who can't DIY...
I'm going to use some extra fancy parts in this next one.

playon · Post by **playon** » 01 May 2009, 06:16

Yep the Honeybee has to be early in the chain IMO if you want to stack it. My problem with the Honeybee is that I hear some weird stuff going on in the low end, even at the neutral "nature" setting. I first noticed it when I tried to use it for a session and then later at home. I ended up getting rid of it, but I'll have to try building this thing. I like low-gain overdrives and they usually play well with other pedals, esp I'm looking for ones that do not use an op-amp.

Whoismarykelly · Post by **Whoismarykelly** » 01 May 2009, 06:44

soulsonic wrote:Great Success!

I have to get another one built now to send to Donner so he can pass it around. Looks like it will be a popular build... I need to get the kit thing together, and I'll probably have to start building them for people who can't DIY...
I'm going to use some extra fancy parts in this next one.

I think mine was all metal films and panasonic caps. The 470pf was a kemet box ceramic and for some reason I only have 33k resistors in half watt carbon comp so I have a mojo resistor in mine.

NOC3 · Post by **NOC3** » 01 May 2009, 15:48

Slightly off topic,

I noticed that the lettering on both soulsonic's and whoismarykelly's build looks the same. What are you guys using to do that? Would you mind sharing where to find it? Looks like a stamp, what kind of paint/ink are you using with it?

Also Soulsonic, what is the sonic advantage of using positive feedback on Q1 to increase its gain VS. just setting the gain of Q1 higher? Just seems like the positive/negative feedback would be working against each other there.

Fuzzer · Post by **Fuzzer** » 01 May 2009, 16:10

soulsonic wrote:It's a rubber stamp kit I got from a craft store. The ink is solvent-based stamp ink.
Fuzzer wrote:How do you do that labels Soulsonic?

It's from another thread, I asked the same thing.

soulsonic · Post by **soulsonic** » 01 May 2009, 22:36

NOC3 wrote:Also Soulsonic, what is the sonic advantage of using positive feedback on Q1 to increase its gain VS. just setting the gain of Q1 higher? Just seems like the positive/negative feedback would be working against each other there.

The main advantage of the positive feedback is that it takes the place of an emitter bypass condensor. The result is less space taken up on the board and less failure-prone components. It also has the advantage of less phase shift of the signal due to the elimination of the time delay component introduced by the bypass caps.... this can very well be responsible for the increased "transparency" of the sound. You may think that the positive and negative feedback networks work against each other, but as you can see, they are happening at different frequencies, so it becomes a crucial part of the overall tone-shaping of the circuit. And, if the gain of Q1 were set higher, it may distort, and we don't want it to distort.
Plus, projects like this should be new learning experiences, and I figured these feedback techniques would be good to learn about. They are old old tricks that are tried and true... stuff straight out of the big red RCA book. Another thing to note is that whether an active component is a transistor, or a tube, or an opamp, they all can be used in similar ways when it comes to sound shaping.

RnFR · Post by **RnFR** » 02 May 2009, 00:00

did you ever find the formula for the positive FB ratio?

soulsonic · Post by **soulsonic** » 02 May 2009, 00:35

RnFR wrote:did you ever find the formula for the positive FB ratio?

Actually... no, not specifically... at least not in something quick and easy. The formula I found had to do with positive feedback between the cathodes and its effect of increasing the plate load resistance of the second stage... I'm going to try and translate it into something more digestible, but that means that I will need to digest it first, and higher math isn't my strong point. I guess I could just put the whole section up here verbatim, and maybe someone better with math can explain it.

Greg · Post by **Greg** » 03 May 2009, 04:45

Wow.. sounds really nice.
Thanks for the clip.

repetitive riffs are the best way to compare things..

earthtonesaudio · Post by **earthtonesaudio** » 04 May 2009, 12:56

This combo pos/neg feedback arrangement got me thinking, wouldn't it be cool to have a feedback looper pedal that had maybe a pos/neg blend with some tone controls perhaps?

I gotta get a copy of the "big red" RCA book someday...

playon · Post by **playon** » 04 May 2009, 22:59

Greg_G wrote:Wow.. sounds really nice.
Thanks for the clip.

repetitive riffs are the best way to compare things..

I agree, I'd much rather hear what you did than endless lead guitar wanking. I like to hear some chords played. It sounds really good for going direct.

soulsonic · Post by **soulsonic** » 05 May 2009, 06:02

The thing about feedback loopers is that they only really freak out if it's a positive feedback situation - that's why they don't seem to work with some pedals. The idea feedback looper (which I've designed and have yet to build....) would have a polarity flipping switch so that you adapt it to any pedal and still get oscillation.
As far as tone controls go... of course! See my TWMNBN freakout noise fuzz; the different value caps in the loops are there for good reason! Touch terminals add an entirely new dimension as well. (note: if you build a TWMNBN, you should probably use a higher value for the "freakout" pot...10k doesn't really do much, I have no idea now why I chose that value!)

Yes, that RCA book is unbelievably useful. It has top-notch information about everything! I'm pretty sure there's a CD-ROM version of it available.
I also scored a copy of Tremain's Audio Cyclopedia a few months back... that's another beast of essential info!

earthtonesaudio wrote:This combo pos/neg feedback arrangement got me thinking, wouldn't it be cool to have a feedback looper pedal that had maybe a pos/neg blend with some tone controls perhaps?

I gotta get a copy of the "big red" RCA book someday...

JiM · Post by **JiM** » 05 May 2009, 11:25

earthtonesaudio wrote:I gotta get a copy of the "big red" RCA book someday...

Not as bench-practical nor collectible as the original, but here is the knowledge nevertheless :
http://geek.scorpiorising.ca/RDH4.html
http://frank.yueksel.org/other/RCA/Radi ... index.html
http://www.pmillett.com/technical_books_online.htm (along with lots of other books of interest)