Search found 478 matches

by grrrunge
13 Dec 2018, 20:56
Forum: DIY Stompbox designs
Topic: Yet another OD idea
Replies: 11
Views: 3460

Re: Yet another OD idea

My thought exactly Baja!
Whichever pair of diodes is clipping the most would depend on the gain setting of U3, as i see it.
Looks cool though Phil! How does it sound?
by grrrunge
29 Mar 2018, 06:01
Forum: Parts Sourcing & Trading
Topic: 1:1 transformer (for audio isolation)
Replies: 20
Views: 7516

Re: 1:1 transformer (for audio isolation)

What I found rather interesting for this application were the Wurth WE-DD inductors that were recently put to my attention: http://katalog.we-online.de/en/pbs/WE-DD As an example the 744878101 is quoted 2.16 eur/pc at Mouser. With DC-resistances ranging from 0.03Ω to 1.4Ω, i guess you'll have a har...
by grrrunge
29 Mar 2018, 05:40
Forum: Parts Sourcing & Trading
Topic: Can I get a specially ordered reverse audio curve?
Replies: 6
Views: 2612

Re: Can I get a specially ordered reverse audio curve?

Lots of manufacturers make reverse logarithmic potentiometers. Look for reverse log, anti log, reverse audio taper etc. - they should be rather easy to find. :thumbsup
by grrrunge
21 Feb 2018, 12:58
Forum: Amplifiers
Topic: Krank Rev Jr Pro 50W
Replies: 5
Views: 2395

Re: Krank Rev Jr Pro 50W

Here goes! Have fun :) https://www.dropbox.com/s/gm3t640z7usj0bv/krank_rev_jr_pro_50w_1.png?dl=0 https://www.dropbox.com/s/aby9bs02ixxirwh/krank_rev_jr_pro_50w_2.png?dl=0 https://www.dropbox.com/s/dbqmbd686mdjftl/krank_rev_jr_pro_50w_3.png?dl=0 https://www.dropbox.com/s/3vn80m106dl91nk/krank_rev_jr_...
by grrrunge
16 Feb 2018, 09:12
Forum: Amplifiers
Topic: Krank Rev Jr Pro 50W
Replies: 5
Views: 2395

Re: Krank Rev Jr Pro 50W

The preamp board is pretty much done - this was a messy bugger to trace out. When comparing it to the Mesa and Soldano amps I've otherwise worked on, even the japanese SP-77 knockoff sports a nicer PCB layout :lol:
by grrrunge
14 Feb 2018, 16:00
Forum: Boutique Stompboxes dissected...
Topic: Friedman BE-OD Pedal [traced]
Replies: 663
Views: 190580

Re: Friedman BE-OD Pedal [traced]

I could be wrong, but I certainly see a lot of traces and no ground plane on the top side of his PCB. My guess is that a poor grounding scheme and ditto choice of component placement is the major contributor to the noise floor in this case.
by grrrunge
13 Feb 2018, 20:33
Forum: Boutique Stompboxes dissected...
Topic: Friedman BE-OD Pedal [traced]
Replies: 663
Views: 190580

Re: Friedman BE-OD Pedal [traced]

Ive been using my BE-OD as a booster lately for tube amps. It's pretty great for this apart from the noise floor Has anyone figured out a way to drop the noise floor down a bit? I'm wondering if a opamp swap might help as a first step Is that the original production model you're using, or a clone? ...
by grrrunge
11 Feb 2018, 18:02
Forum: Amplifiers
Topic: Krank Rev Jr Pro 50W
Replies: 5
Views: 2395

Re: Krank Rev Jr Pro 50W

Looks like they have quite a bit in common, though it seems this PCB accomodates circuitry to switch between a solid state or tube buffered effects loop instead of multiple master volumes ;) Here's the work in progress. It's linking to my dropbox, so this will always be the latest revision. https://...
by grrrunge
09 Feb 2018, 01:41
Forum: Amplifiers
Topic: Krank Rev Jr Pro 50W
Replies: 5
Views: 2395

Krank Rev Jr Pro 50W

I Haven't had much action around these parts lately, and the channel switching in this bad boy started acting up, so let's get the trace show running. I haven't seen schematics for these elsewhere :horsey: First up: Board A - the preamp board. IMG_7828.jpg IMG_7837.jpg combo1.jpg combo2.jpg combo3.j...
by grrrunge
30 Dec 2017, 13:02
Forum: Modern Stompbox Effects (1975 - ...)
Topic: TC SPARK BOOSTER MINI [schematic]
Replies: 26
Views: 11293

Re: TC SPARK BOOSTER MINI [schematic]

You are correct that miller capacitance is involved. You also need to know the current gain of the pnp, the re of the pnp, and the output impedance of the j-fet stage. Once that is all done, it doesn't really matter because the feedback loop will correct the response (to the limits that it can). Th...
by grrrunge
30 Dec 2017, 12:36
Forum: Modern Stompbox Effects (1975 - ...)
Topic: TC SPARK BOOSTER MINI [schematic]
Replies: 26
Views: 11293

Re: TC SPARK BOOSTER MINI [schematic]

For a fairly accurate estimate, assume the usual textbook conditions for DC analysis; Vbe=0.7V, VT=25mV and Hfe=infinite: The bias current for T1 and T4 is half of the current generated by T2 and T3: IC2=IR8=Vbe/R8=7mA IE1=IE4=IC2/2=3.5mA To find the gain of the differential stage, we find re and th...
by grrrunge
28 Nov 2017, 23:21
Forum: Amplifiers
Topic: Orange Crush 10 Gutshots
Replies: 4
Views: 4216

Re: Orange Crush 10 Gutshots

kciuq wrote:
e45tg4t3 wrote:Hi there guys.... i thought may some of you are interested in gutshots auf the Orange Crush 10 Solid State Amp... so here they are...

http://www.megaupload.com/de/?d=Q48SUEL1
Re-Upload Schematic please.
It's right here: https://www.freestompboxes.org/viewtopic.ph ... 69#p260277 ;)
by grrrunge
14 Nov 2017, 06:43
Forum: Modern Stompbox Effects (1975 - ...)
Topic: TC SPARK BOOSTER MINI [schematic]
Replies: 26
Views: 11293

Re: TC SPARK BOOSTER MINI [schematic]

You do technically have a point about the dominant pole. Adjusting C8 changes the dominant pole. C6 however, like I said- Try it! Slew rate distortion might be the next big thing. Also; C8 is in the negative feedback loop, and as such it is affecting the closed loop frequency response, not the open...
by grrrunge
14 Nov 2017, 06:41
Forum: Modern Stompbox Effects (1975 - ...)
Topic: TC SPARK BOOSTER MINI [schematic]
Replies: 26
Views: 11293

Re: TC SPARK BOOSTER MINI [schematic]

It's predictable? What is the formula to predict it? Let's put -3dB @ 1kHz. What is the value of C6? Once you calculate your small signal equivalents its trivial to employ the Miller theorem in order to calculate the open loop frequency response. I'll try to give an example, when i get off work :) ...
by grrrunge
14 Nov 2017, 00:04
Forum: Modern Stompbox Effects (1975 - ...)
Topic: TC SPARK BOOSTER MINI [schematic]
Replies: 26
Views: 11293

Re: TC SPARK BOOSTER MINI [schematic]

Increasing C6 is a creative idea and should be experimented with. Think of C6 as being part of the open loop gain calculation. If C6 is increased, the feedback mechanism will try to compensate for this. At larger and larger values of C6, you will get greater and greater slew-rate limiting. The ampl...
by grrrunge
12 Nov 2017, 21:58
Forum: Modern Stompbox Effects (1975 - ...)
Topic: TC SPARK BOOSTER MINI [schematic]
Replies: 26
Views: 11293

Re: TC SPARK BOOSTER MINI [schematic]

Hey guys, I have experience modding tube amplifiers but not pedals. I would like to turn this into a tube screamer type boost that rolls off some highs and lows. Where would be the best places in the circuit to do this ? I would imagine a 22nF (starting point) capacitor would cut some lows and then...
by grrrunge
19 May 2017, 11:19
Forum: Pedal Debugging & Troubleshooting Support
Topic: Fuzzface Build
Replies: 3
Views: 183

Re: Fuzzface Build

If the pedal sounds too flabby, its often because the clipping stage is being hit with too much low-frequency content.
For a tighter sound, try lowering the value of the 2µ2 input capacitor. I built a couple of fuzz faces a while back with 470n capacitors instead of the 2µ2 - they sounded awesome :)
by grrrunge
04 May 2017, 12:32
Forum: Boutique Stompboxes dissected...
Topic: Seppuku - Fuzz Overloader [traced]
Replies: 42
Views: 17370

Re: Seppuku - Fuzz Overloader [traced]

For some weird reason OSHpark turned off sharing for the PCB i designed. Here's a new one, in case someone wants to build one...
https://oshpark.com/shared_projects/uM1MDI0a
top.png
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bottom.png (10.95 KiB) Viewed 84 times
by grrrunge
04 May 2017, 11:56
Forum: Ready-To-Build Effect Projects
Topic: Condor Cabinet Simulator, RunOffGroove
Replies: 18
Views: 1017

Re: Condor Cabinet Simulator, RunOffGroove

I just realized people are still using my layout, so I gave the board a quick do-over for aesthetics reasons :P The "modern mod" values has been included on the silk screen, FET-pinout has been denoted on the board, and all other text has been tidied up :) New project link here: https://oshpark.com/...
by grrrunge
10 Feb 2017, 09:12
Forum: Modern Stompbox Effects (1975 - ...)
Topic: The great "I'd like to see the guts of" thread
Replies: 224
Views: 339965

Re: The great "I'd like to see the guts of" thread

kingmafw wrote:Here are some guts of the DOD Boneshaker...
Awesome! could you get some detailed pics of the standoff boards as well?