Search found 79 matches

by turbofeedus
20 Jan 2022, 16:16
Forum: Boutique Stompboxes dissected...
Topic: Analogman - King of Tone [traced]
Replies: 465
Views: 240184

Re: Analogman - King of Tone [traced]

Who would have thought there's be a necro post in the infamous KoT thread :o Anywho, I did some more plots on KoT diodes, expanding specifically the 1S1588. I had three different "styles" of (allegedly) 1S1588 in my collection, which I will refer to as "big", "mid", and...
by turbofeedus
21 Jul 2021, 16:50
Forum: Boutique Stompboxes dissected...
Topic: Hagerman Amplification (schematics)
Replies: 9
Views: 2271

Re: Hagerman Amplification (schematics)

I was wondering when I was going to see someone using those hammond flanged enclosures
by turbofeedus
13 Feb 2021, 03:05
Forum: Boutique Stompboxes dissected...
Topic: Benson - Germanium Fuzz [traced]
Replies: 21
Views: 8357

Re: Benson Germanium Fuzz [traced]

Curiosity got the better of me...
Tested with Peak DCA75.
Q1
hfe: 98
leak: 20uA

Q2
hfe: 79
leak: 82uA

Q1 is marked 2N527 BSC2040
Q2 is marked 2N527SEL2049

gefuzz-7.JPG
by turbofeedus
11 Feb 2021, 12:42
Forum: Boutique Stompboxes dissected...
Topic: Benson - Germanium Fuzz [traced]
Replies: 21
Views: 8357

Re: Benson Germanium Fuzz [traced]

george giblet wrote: 11 Feb 2021, 06:12
John Hollis's Rock Face (2001) tries to achieve a similar goal but with less power,
http://www.hollis.co.uk/john/rockface.jpg
There's something kinda fun about the benson concept though, like sure, just slap couple hot resistors on there with some thermal paste. Done.
by turbofeedus
11 Feb 2021, 03:48
Forum: Boutique Stompboxes dissected...
Topic: Benson - Germanium Fuzz [traced]
Replies: 21
Views: 8357

Re: Benson Germanium Fuzz [traced]

The collector voltage is floating right around -4.2V, obviously fluctuating as the heating circuit turns on and off. You can goop over the power resistors and Ge transistors with polyurethane sealant or other non corrosive compound, in order to have more thermal mass and increase the on time and in...
by turbofeedus
11 Feb 2021, 02:07
Forum: Boutique Stompboxes dissected...
Topic: Benson - Germanium Fuzz [traced]
Replies: 21
Views: 8357

Re: Benson Germanium Fuzz [traced]

A couple observations; To confirm a couple earlier calculations, the V- is right about 8V, and the threshold voltage at pin 2 is ~1.83V. The collector voltage is floating right around -4.2V, obviously fluctuating as the heating circuit turns on and off. The pots are marked "keeley", sugges...
by turbofeedus
11 Feb 2021, 00:05
Forum: Boutique Stompboxes dissected...
Topic: Benson - Germanium Fuzz [traced]
Replies: 21
Views: 8357

Re: Benson Germanium Fuzz [traced]

If the battery voltage stays constant, it's sort of a temperature control in that it is using collector voltage vs temperature to control the heating. However, if the battery voltage changes it also try to keep the collector voltage to some ratio of the supply. Not quite as the buffer base-emitter ...
by turbofeedus
10 Feb 2021, 15:31
Forum: Boutique Stompboxes dissected...
Topic: Benson - Germanium Fuzz [traced]
Replies: 21
Views: 8357

Re: Benson Germanium Fuzz [traced]

Good stuff Jose and George. I understand the concept here, that temperature regulation isn't inherently the purpose of the warming circuit, but because germaniums are so temperature sensitive, holding the trans at a relatively constant temperature is necessary to stabilize the bias point, and theref...
by turbofeedus
10 Feb 2021, 00:21
Forum: Boutique Stompboxes dissected...
Topic: Benson - Germanium Fuzz [traced]
Replies: 21
Views: 8357

Re: Benson Germanium Fuzz [traced]

A100k seems like a good value for input resistance (impedance) and for the volume pot but it is completely useless for a gain/fuzz pot. I see there's a B1k pot in the picture of the actual pedal. That would make an excellent gain/fuzz pot. Maybe you can check and update the schematic. Thanks for tr...
by turbofeedus
09 Feb 2021, 18:46
Forum: Boutique Stompboxes dissected...
Topic: Benson - Germanium Fuzz [traced]
Replies: 21
Views: 8357

Re: Benson Germanium Fuzz [traced]

I'm not slick enough to understand the warming circuit, but it looks similar to these thermostat designs: http://www.craig.copperleife.com/tech/thermo/ Maybe someone more technically adept can explain. Also the schematic is unverified. I just moved house and am a bit scatterbrained, might have misse...
by turbofeedus
09 Feb 2021, 02:26
Forum: Boutique Stompboxes dissected...
Topic: Benson - Germanium Fuzz [traced]
Replies: 21
Views: 8357

Re: Benson Germanium Fuzz [traced]

schem1.png
UPDATE #1: Fixed gain pot value from A100K to B1K
by turbofeedus
08 Feb 2021, 17:05
Forum: Boutique Stompboxes dissected...
Topic: Benson - Germanium Fuzz [traced]
Replies: 21
Views: 8357

Benson - Germanium Fuzz [traced]

Working on a schematic now
It's a fuzz face, but with an interesting heating circuit using a pair of carbon comp resistors.

gefuzz-6.JPG
gefuzz-1.JPG
by turbofeedus
21 Nov 2020, 11:45
Forum: Boutique Stompboxes dissected...
Topic: Monster Effects - Mastortion
Replies: 7
Views: 3944

Re: Monster Effects - Mastortion

nooneknows wrote: 21 Nov 2020, 10:58 YATS with a fixed tone shaping
yep. To be fair, I think they admitted as much.
by turbofeedus
21 Nov 2020, 04:13
Forum: Boutique Stompboxes dissected...
Topic: Monster Effects - Mastortion
Replies: 7
Views: 3944

Re: Monster Effects - Mastortion

Picked up one of these on Reverb as "not working".... seems fine to me :) Enjoy! Image gallery EDIT: I was staring at the schematic, trying to wrap my head around why there's a fudgin' FWBR in there. I knew there must have been something I missed. See updated schematic. Polarity protection...
by turbofeedus
17 Nov 2020, 04:04
Forum: Boutique Stompboxes dissected...
Topic: JHS Prestige
Replies: 9
Views: 4841

Re: JHS Prestige

bbkassel wrote: 14 Nov 2020, 14:22 Inside view...
That's an... interesting grounding method. Yikes.
by turbofeedus
13 Nov 2020, 11:54
Forum: Amplifiers
Topic: Requesting Laney Klipp circuit analysis.
Replies: 6
Views: 2670

Re: Requesting Laney Klipp circuit analysis.

Hi turbofeedus, That schematic looks "almost" like other Hiwatt amps, but the difference lies in the second preamp tube and associated components that are arranged to create insane amounts of distortion. Cheers, Jose Ohhh I see, that's weird I could have sworn the klipp thing was a separa...
by turbofeedus
08 Nov 2020, 23:14
Forum: Amplifiers
Topic: Requesting Laney Klipp circuit analysis.
Replies: 6
Views: 2670

Re: Requesting Laney Klipp circuit analysis.

Been slowly getting around to learning how to draw load lines and all the stuff related to tube charts but I was wondering how the Klipp circuit on the Laney Klipp amp works. I got an idea how the bypass is executed but I was wondering what is going on in the Klipp tube stage that creates the hybri...
by turbofeedus
28 Oct 2020, 00:50
Forum: Parts & Tools Sourcing & Trading
Topic: BF245A ebay testing
Replies: 0
Views: 1940

BF245A ebay testing

After some success with the 2SK117, I wanted to push my luck. Obsolete JFETs are still on the menu, this time some (allegedly) Fairchild BF245A ( datasheet ). ebay item link: https://www.ebay.com/itm/284031825834 ebay seller xripley from Czech Republic: https://www.ebay.com/usr/xripley From a batch ...
by turbofeedus
18 Oct 2020, 01:47
Forum: Boutique Stompboxes dissected...
Topic: smallsound/bigsound - mini [traced]
Replies: 51
Views: 34655

Re: smallsound/bigsound - mini [traced]

This article is a good read for anything regarding JFET amplification.
http://runoffgroove.com/fetzervalve.html
by turbofeedus
16 Oct 2020, 05:00
Forum: Boutique Stompboxes dissected...
Topic: smallsound/bigsound - mini [traced]
Replies: 51
Views: 34655

Re: smallsound/bigsound - mini [traced]

Hello! Just built the ssbs mini and it’s sounds awesome ... ! .. except that I cant get the bias pot and trim to work properly. The lowest voltage on the 5457 drain I can muster is approx 5v via the trim.. the bias pot also only has a 2v range (max is 7v min is 5v). It’s making some difference alth...