Engineer's Thumb Comp and Baby Bactrian (mini Llama) - both on perf!

[midwayfair]

The Baby Bactrian:



How much fun was it to call the last picture "baby bactrian guts?"  

It's "almost a Red Llama" - I had to sub a 120pf cap for the 100pf cap because I ran out of 100s. I'm not entirely convinced it was an okay substitution. This one sounds a little harsher than the other llama I built, even though I'm almost certain it should have reduced the highs.

The case sure came out better than last time! (http://www.madbeanpedals.com/forum/index.php?topic=4327.0) But still not perfectly by any means. It was ridiculously humid here the last couple days and the paint just wouldn't dry properly, so there's some dirt and finger marks and touch ups.

And the Engineer's Thumb:


It's a feed forward compressor designed by MerlinB (aka ValveWizard). He posted the schematic over on DIYStompboxes. This was by far the most complicated thing I've tried to tackle on perfboard. I think I did okay with the layout - MerlinB's etch layout was actually a little more complicated (it had more jumpers, though it was a little smaller). Sabro also did a vero layout, but it won't fit in a 1590B and I hate working with vero most of the time because it's so wasteful of space. (I also didn't feel like decoding and reversing the millenium bypass used on the Vero).

Generally, it sounds a little like a Dynacomp, but the bright switch corrects the loss of highs without turning it into a janglebox (which I think sounds harsh), and there's both more and less compression and transparency available in the stock design. It's also got a TON of headroom. Enough to run a boost in front and almost certainly enough to take any guitar pickup you can throw at it. If you're interested in reading more, I suggest checking out MerlinB's thread. http://www.diystompboxes.com/smfforum/index.php?topic=97123.0

I also posted a little review there and more details of my initial experiences with the pedal's sound.

[TheCobbenator]

Diggin it!! I like the hand painting!! Something i've been wanting to get more into. I've been super curious about that comp since I found that thread the day he posted it by chance... Instead of writing that 10-page paper on feminism last month. Shinfo

I gotta try it!

[mgwhit]

Nice builds!  Your perfboard gut shots look cool...and make me feel like a chump.  The only perf project I ever started is still sitting half-finished in a box somewhere.

Re: the Llama, I just read a review of the reissue in GP where they frequently lamented the lack of a treble roll-off tone pot, but my recent build doesn't have any harsh treble at all.  I wonder if this is just a circuit where slight variances (or wide tolerances) can make a dramatic change?  If only we knew how those inverters worked their magic!

P.S. I consider Merlin's book on guitar pre-amps to be the bible on the subject.  I've only had a few seconds to look at that thread, but I have a strange feeling that this one might drag me (kicking and screaming) into perf/vero/etching.  Thanks for the link!  I'll try to get through it all later tonight.

[timbo_93631]

 I also consider Merlin's writing on tube amp design to be nearly holy.

[jkokura]

Would likely enjoy a link on that one...

My experience with Merlin is he's a great guy.

Jacob

[midwayfair]

Jacob, here's the link: http://www.freestompboxes.org/viewtopic.php?f=13&t=17213

I read everything MerlinB's written on his site after discovering his stompbox designs. Even if I don't plan on touching the actual circuitry in amps (because I want to live), his stuff really helped me understand what I could make an amp do. And some of the principals are no doubt transferable to stompboxes.

[jkokura]

It is good. Too bad I don't understand half the stuff MicTester is saying. I think he's a member here too...

Please by kind to all who write around here, it's only polite.

Jacob

[midwayfair]

It is good. Too bad I don't understand half the stuff MicTester is saying. I think he's a member here too...

Please by kind to all who write around here, it's only polite.

Jacob

Fair enough. I'll edit my other post.

[jkokura]

Thanks boys! We like to keep things positive here, and I hope you keep me in line if I get grumpy...

But back to the topic at hand - how does the engineers thumb sound? Live up to Merlin's hype?

Jacob

[midwayfair]

Thanks boys! We like to keep things positive here, and I hope you keep me in line if I get grumpy...

But back to the topic at hand - how does the engineers thumb sound? Live up to Merlin's hype?

Jacob

I put my long-winded review in this post:
http://www.diystompboxes.com/smfforum/index.php?topic=97123.msg851927#msg851927

Retyping it here might contribute to global warming.

In brief: Overall, I much prefer the sound over a Ross-style circuit, but I found the stock ratio pot value to be overkill with low-output pickups. It's got some of the transparentness of optical comps with the character of Dynas.

mgwhit: Go for it, man! I prefer perfboard to etches, believe it or not. It's more visual, and closer to reading a schematic or working on a breadboard, so I find it very intuitive, if a little time consuming.