DAM FR-69

[rocket88]

i'm thinking of building a DAM FR-69 which is basically a Mosrite Fuzzrite, or the Ge version of the FR-70 which Mark had made and is posted on the main site. i found a layout and schematic from the old turretboard site, but felt it was too big for no reason, so i made my own layout.

here's a link to the original turretboard layout, and below is mine. if someone could give it a once over just to make sure i didn't miss anything i would appreciate it. plus, a new Ge fuzz on this day of blizzards....

[Silver Blues]

Checked it, looks good

[rocket88]

Awesome. Thanks buddy

[Beaker]

Nice layout!

I have built this layout using MP38s:

http://tagboardeffects.blogspot.co.uk/2010/07/mosrite-ge-fuzzrite.html

 and incorporated the tone switch mod from this layout:

http://tagboardeffects.blogspot.co.uk/2010/02/mosrite-fuzzrite.html

It screams!

I hope the FR 69 sounds as good.

[rocket88]

In the video it sounds like badass 60's garage rock. With it being pnp, there's a lot of transistors to choose from. I'll take a look at the tone switch and might incorporate it. I dig the suggestion.

[Beaker]

Yeah, it's easy done as it's offboard. I can't see any reason why it should not work just as well as on the NPN layout.

[rocket88]

btw, ambiguous demo video.

[rocket88]

so i finally got around to building this one. the layout is verified, i just had to make a correction in the notes for the layout. i'm still playing around with transistors, but i can tell you this much so far. Q1 should be around 90-110hfe, but closer to 100hfe. the higher the gain of Q1 the pedal can get very very hissy, as in a massive amount of white noise when you stop playing. I'm still working on the correct gain for Q2 to get it to sound like the actual thing, so i'll report more when i figure it out.

so far sounds pretty good. i think the suggestion of the 22k resistor on the switch is actually incorporated into the schematic already, as there's a 22k resistor from Depth 3 to ground, which i don't see in any schematic for the regular Ge fuzzrite. if you wanted to you could take it off the board and put it on a switch. i can modify the layout if anyone really wants that done.

[rocket88]

think i cracked it. my gf left me alone for a bit on V-day so i got to do some research and playing with this effect. now, i forget who mentioned it, i think it was travis, that this effect was setup origianlly to run AC128's and OC81D's that are reissues. so i began to do a lot of digging into the hfe's of the reissues since the suggested values made this sound like utter shit. i mean it was grainy, gated, noisey, you name it, i mean i nearly went heath on it and take a dremel to it.

now, to the important part. the AC128's in Q1 is without a doubt in the neighborhood of 90-110hfe, it gets more compressed the closer you get to 120hfe, and over 120hfe mine started to make a shit ton of white noise making it unusable. now the interesting thing is the reissue OC81D's seem to have a max hfe in the 40's, so after playing with values suggested for the fuzzrite which were in the 60's, i popped in an MP20a with hfe in the 40's and holy shit does it sound awesome. i then tried one in the 30's and it started to get gated, so i tried one in the 50's and same issue.

then i tried different model transistors: MP41a, MP16A, and MP39B. each one changed the tone of the effect just a bit. i ran out of time to try others, but i ended up sticking with the MP39B. The MP20a was rather neutral, the MP41a was a little fuller, MP16a just didn't sound right can't put my finger on it, and the MP39B seemed to be in between the MP41a and MP20a. which is awesome because i bought some of them to try and they were all low gain, most being in the 40's, and i thought they were going to just go to waste or end up in buffers, but i know they're used in the joe bonamassa fuzzface, and now they sound awesome in this.

so, long story short:
Q1: 90-110hfe, i used an AC128
Q2: 40's hfe, i used MP38b

it sounds like 60's garage/psychedelic rock goodness, but has a little more balls on the top end.

[Heath]

rocket88 wrote

i nearly went heath on it and take a dremel to it

Behold... my Legacy.

[rocket88]

Hand to god heath, I had the dremel loaded and sitting right next to me. Then I just thought that I might have the transistors wrong.

[Heath]

That's even better, because after posting, I decided to build this at, yeah, almost 3am... I used PN41 or whatever, 40hfe and a Chinese 3AX type at 99hfe.  

I had a piece of vero sitting out that was nearly perfect, except it was one column short, so I set the rightmost link diagonally, starting under the resistor, thereby shrinking it by one column (ugly, but it kept me from having to cut a new little piece out of a bigger board at near 3am).  Sounded pretty simple.

Thing is, I'm not used to powering positive ground -9v stuff.  I have a -9v feed from the power supply I built, but I wasn't thinking about wether it was tip neg or tip pos.  Right or Wrong, I got nothing out of it.  I double checked everything and didn't find anything wrong.  So I built a little negative voltage inverter daughter-board and wired it up and plugged things in +9v, still nothing.

Fuck me.  It was way too late to bother trouble shooting at that point.  I figure, and I could be idiotically wrong about this, the only thing I would have potentially damaged by plugging in the wrong polarity, or whatever, is the 1 electrolytic and possible the transistors, right?  Non-polarized caps and resistors don't give a shit (unless voltage or wattage is exceeded), if I understand correctly.

"Cut dat beetch!" I heard a small muffled voice say from the drawer where I keep the dremel secured.  I don't know why mine has a Jamaican accent, he just does.

[anders]

Built and it roars!  Thanks for the layout! This is going into the box!

[rocket88]

Awesome. Glad to make another positive contribution. Out of curiosity, what transistors did you end up using and did you follow the gains I found worked for me? Curious to see the if there's differences between my build and others, for science .

[anders]

Yeah, I followed your gains with NPN Germs, MP38A for Q1 (hfe 85) and MP38 for Q2 (hfe 40). Finally I found use for all these low gain russian germaniums; they're great for Q2 in fuzzrites, orpheums and some other buzztones...

[Heath]

Don't hate me, but I finally rebuilt this one and went through all of the transistor choices I had available and... I just do not like this circuit at all.  Sounds to me like a hundred pieces of velcro being ripped apart.  Definitely not my thing.  No fault of Zach's layout, I should have listened closer to the video demo.  Mine sounded almost just like it, but it's butt-ugly sounding to me.

I WILL say, however, it lacks the gatey-ness which turns me off of a lot of fuzz circuits.  It's nicely tuned in that aspect.

This is probably a perfect example of why I end up really loving the less popular fuzzes.  Everyone seems to love the MkI and II Tonebenders, but I love the MkIII which seems to be the less popular version.  Also, I have a lot of trouble finding a "muff-style" circuit I like.  

So, yeah, I'm definitely in the minority on this.

[Beaker]

Don't look at the Conrad then - this is polite in comparison!

[rocket88]

Suuuuurrrreee Heath, you're not blaming me and the layout, I see how it is now.

But in all seriousness. It's all good and I completely agree about the MKIII tonebenders, I think they're my favorite too, while I still love the other generations there's something about the MKIII that I love.

I compared to this version to the Si version, FR-70, and this is warmer, smoother, and less in you face at all settings. The FR-70 have an ass-ton of treble, and more zipper like then the Ge version. To each his own, and with fuzzes it's even more so with fuzzes. I can't tell you how many times I've been told "hey try this fuzz, it's awesome!!!" and I end up being like "meh, it's ok...." For instance, I played an analogue man sunface, and I just didn't like it, no one bit. Meanwhile, I built my own Ge fuzzface with bias knob and love it. It's hard to find one that really fits you're tastes, not to mention how often do our tastes change in a second. And right now, I've been in a 60's psych rock mood and dig the nasty, raw, seeing the stooges live with iggy cutting himself throwing shit at the audience sound. Btw, don't have sex listening to the stooges, things get crazy and fast.....

[Heath]

Oh, I hear ya.  My favorite "vintagy" fuzzes are my Ge Fuzzface (don't remember model specifics at the moment), my Tonebender MkIII, and The Joe Gore Ge Fiend Face (that's not the real name, just what I call it... )

You'll notice those all tend to be less ragged sounding and more "crunching on a Butterfinger."  I guess on a scale with Static on one end and Distortion on the other, I like fuzzes that lean more towards Distortion.

Al that said, those DAM pedals sure do have a following, which means, to me, that my ears aren't the be-all end-all of what is great and what is not.

BTW, my build sounded damn near exactly like the video demo (well, like one of the samples anyway since they demoed a bunch of different amps) so I believe your layout is perfect.  Good job on this nasty pedal

[Kinski]

Oh. Hell. Yes. This thing sounds so good. I used a voltage converter and a two MP20A transistors. I tried a ton of different HFE on both Q1 and Q2. All the way from 40 hfe to 105 hfe. My ears liked Q1 87 HFE, Q2 74 HFE.

One question, the only setting I like on this thing is with the depth all the way up where it sounds the fuzziest and brightest. Is there a way I can ditch the depth pot and just stick a resistor somewhere?

Thanks for the awesome layout, Rocket88! Gonna 1590A this baby!