Dream Fuzz op amp muff build

[cdwillis]

I assembled this over a couple weeks. I started on it then realized I was missing a few parts, hence the eternity it took to finish. I used a couple resistors from the odds and ends section of my parts stash. Since a couple were 1/2w I had to stand them up. Of course I got the resistors I needed when my capacitors came in, but I hate desoldering so I left the standing resistors in. I've seen both 150pf and 330pf caps in different schematics, so I used a couple sockets to test between them. Right now it has the 150pf cap in place. I haven't tried the larger cap. It'll probably make it smoother, but I don't find this build nearly as scratchy sounding as some of the op amp muff demos I've heard on youtube.

I've never played an op amp muff, so I wasn't sure what to expect. It doesn't sound nearly as full or bass heavy as most of my other muffs. I'd say it may be close to something like the NYC muff as far as low end. The tone bypass option give it a nice full sound. Activating the tone knob cuts signal as I anticipated. What I find strange is turning the tone control counterclockwise / down does remove high end, but also seems to cut a lot the signal down as it goes. I'm guessing this is just how the tone control works since I put the tone control values into the BMP tone stack calculator on the online version of Duncan amps and it shows the signal being cut starting at the bottom of the guitar's frequency range.

Tone control at noon:



Tone control backed all the way down:

 

[fig]

It looks great!

 

[jwyles90]

Clean looking build! I've got one of these lined up pretty soon here and can't wait to see how it sounds. What kind of SPDT toggle did you use? I'm assuming it's the On/On but noticed it doesn't specify in the build docs.

 

[gheorge77]

Clean looking build! I've got one of these lined up pretty soon here and can't wait to see how it sounds. What kind of SPDT toggle did you use? I'm assuming it's the On/On but noticed it doesn't specify in the build docs.

I used an on/on for this build. Nice sounding muff but I prefer the Rams Head and the Russians. I built a Rams Head Number 3 from the Kitrae site and the Civil War in the build docs. Both are awesome.

 

[cdwillis]

I used an on/on for this build. Nice sounding muff but I prefer the Rams Head and the Russians. I built a Rams Head Number 3 from the Kitrae site and the Civil War in the build docs. Both are awesome.

You took the words right out of my mouth. On/on and I also prefer the Russian variants, but I think one of the Triangle variants I've built is my favorite.

 

[gheorge77]

You took the words right out of my mouth. On/on and I also prefer the Russian variants, but I think one of the Triangle variants I've built is my favorite.

My favorite muff right now is a triangle variant, the Hizumitas. Been using it on my board since it was first released by PPCB. I went through my short phase of liking tone benders but I ultimately came back to muffs. Just the best fuzz for the type of music I play these days.

thunderon.bandcamp.com

 

[jeffwhitfield]

I built the AionFX version some time ago. Sounds really freaking cool. However, I noticed some differences between that one and the PedalPCB version in the schematics. As such, figure I’ll build a Dream Fuzz and compare them.

 

[Feral Feline]

Interesting graphs, thanks for that.

 

[jwyles90]

You took the words right out of my mouth. On/on and I also prefer the Russian variants, but I think one of the Triangle variants I've built is my favorite.

I've never really used the Op-Amp variant before, but it's a tie between the Civil War and Ram's Head for me. I figured I'd build the op-amp myself to see if I even like it. I'm also of the mindset that you can never have too much fuzz haha

 

[cdwillis]

I also built the op amp variant because I'd never played one. I think I'm glad I built one instead of spending a lot more money on buying a production version. It doesn't really sound like any other big muff I've ever played, even more so than I expected since it was op amp based. I do wonder if a large part of it is the tone control values. It's been weeks since I've even messed with it, so I should probably get it out and mess around with it again. I think opening it back up and tweaking the tone control values to something a little more traditionally Muffy would really make it sound more pleasing to me. Then if I want more midrange I can just hit the tone bypass toggle.

 

[Coda]

I built the AionFX version some time ago. Sounds really freaking cool. However, I noticed some differences between that one and the PedalPCB version in the schematics. As such, figure I’ll build a Dream Fuzz and compare them.

I believe the Aion version is based on a V5 BMP, where as the PedalPCB is based on the current EHX Opamp Muff reissue…

 

[jeffwhitfield]

I believe the Aion version is based on a V5 BMP, where as the PedalPCB is based on the current EHX Opamp Muff reissue…

Yep, which makes me wonder how much difference there is with the sound.

 

[mdc]

Pick your adjective, but on a quick glance the only substantial difference is C7 (150pF v 330pF)—tone sections are the same, so theoretically the PPCB version might be somewhat "brighter/more aggressive/harsher/etc."

 

[Bricksnbeatles]

Do you have any issues with the tone knob pointer hitting the tone bypass switch?

 

[cdwillis]

It looks close in the picture, but it clears it fine.

 

[Bricksnbeatles]

Pick your adjective, but on a quick glance the only substantial difference is C7 (150pF v 330pF)—tone sections are the same, so theoretically the PPCB version might be somewhat "brighter/more aggressive/harsher/etc."

Don't mean to necropost, but I've been doing some research for accuracy's sake, comparing the Aion schematic to the PPCB so I can build a true V5, rather than a reissue circuit, on the Dream Fuzz board, and it seems that the 150pF vs 330pF matter is actually due to a common schematic error. as you can see here, there are both 150pF and 160pF caps that have been used in V4/5 muffs, but they were also marked with N330, which is just the series, not a 330pF marking. https://www.diystompboxes.com/smfforum/index.php?topic=107247.0

That said, there are a few other differences between the Reissue circuit as seen in the Dream Fuzz, and the V5 as seen in the Aion Corvus. Notable differences are that (using the refdes from the dream fuzz):

• for a V5 muff, R9 should not be connected to the R8/C5 net, but instead tied to ground from that end
• C6 should be replaced with a 1uF cap in place of the default 4u7 cap
• the clipping diodes should be 1n914 instead of 1n4147 (though the diodes used in v5 muffs probably varried from day to day, given the inconsistencies back then.
• C2 and C8 are also boosted up from 1u and 220n respectively, to 10u or 47u, though that's just additional power filtering and shouldn't impact the sound. likewise, c12 (220u) is replaced with a 100u and 100n cap in parallel in the Corvus. again, no difference in actual sound, and that's probably an Aion modification rather than the stock configuration of a V5.
• The Volume pot is suggested to be A100K by Aion. While the volume pots in muffs are one of the biggest inconsistencies from one to another, it seems to be a liberty taken by Aion rather than the original taper, as all evidence I found shows that the value was inconsistent for muff volume pots, but that they were always linear. Regardless, the audio taper seems a worthwhile change.

 

[mdc]

I can't see how any of those changes would make any sort of noticeable difference but if you happen to A/B please do report back!

Also, per this note:

• for a V5 muff, R9 should not be connected to the R8/C5 net, but instead tied to ground from that end

The two schematics are numbered differently, but look the same around this particular resistor. R8 on the aion schematic is labeled "omit" which leaves you with R6/R7/C4 which looks the same as R8/R9/C5 on the ppcb schematic. Are you referencing a third schematic?

 

[Bricksnbeatles]

I can't see how any of those changes would make any sort of noticeable difference but if you happen to A/B please do report back!

Also, per this note:

• for a V5 muff, R9 should not be connected to the R8/C5 net, but instead tied to ground from that end

The two schematics are numbered differently, but look the same around this particular resistor. R8 on the aion schematic is labeled "omit" which leaves you with R6/R7/C4 which looks the same as R8/R9/C5 on the ppcb schematic. Are you referencing a third schematic?

In the notes they mention that it’s a modification (devised by analog guru) to the original circuit, but that for the stock V5 you should populate R8 and omit R7 as well as jumper C5 (in this case going by the Aion refdes)