Search found 16 matches

by j_flanders
21 Dec 2019, 00:32
Forum: Modern Stompbox Effects (1975 - ...)
Topic: Harley Benton - PA100 Power Attenuator [schematic]
Replies: 30
Views: 12808

Re: Harley Benton - PA100 Power Attenuator [schematic]

Looks weird having a bridge rectifier as part of the speaker circuit Here's another project using a similar setup: https://i.screwtopdb.com/ftl274mqd.jpg https://arduino.openexpanse.com/en/arduino.openexpanse.com/article/id/330 I measured the AC voltage at the speaker output of my amplifier and it ...
by j_flanders
20 Dec 2019, 22:23
Forum: Modern Stompbox Effects (1975 - ...)
Topic: Harley Benton - PA100 Power Attenuator [schematic]
Replies: 30
Views: 12808

Re: Harley Benton - PA100 Power Attenuator [schematic]

Here's what I traced when I got the unit which is slightly different from the schematic posted above. I didn't trace the line out or the mic out btw.
Image
by j_flanders
20 Dec 2019, 22:20
Forum: Modern Stompbox Effects (1975 - ...)
Topic: Harley Benton - PA100 Power Attenuator [schematic]
Replies: 30
Views: 12808

Re: Harley Benton - PA100 Power Attenuator [schematic]

Thanks for the reply phatt. Great post, highly informative! Love the load test smiley. :) I'll check out some of the references (UA, Guytron). Bottom line is that Mr. Benton did well making the resistive load higher and that I certainly shouldn't change that 16Ohm switching jack to get closer to 4 O...
by j_flanders
20 Dec 2019, 01:00
Forum: Modern Stompbox Effects (1975 - ...)
Topic: Dunlop JDF2 Fuzz Face [schematic]
Replies: 13
Views: 3285

Re: Dunlop JDF2 Fuzz Face [schematic]

Oh, and because the thermistor and pot values were missing in your schematic.

(where's the post edit button?)
by j_flanders
20 Dec 2019, 00:59
Forum: Modern Stompbox Effects (1975 - ...)
Topic: Dunlop JDF2 Fuzz Face [schematic]
Replies: 13
Views: 3285

Re: Dunlop JDF2 Fuzz Face [schematic]

I'm not seeing any difference between your schematic and mine (other than mine has all the header connections). Maybe I'm missing something. What makes it the "correct" one? You gave the impression having doubts about the one you posted so I posted one from a pedal I traced. Yours is nice when work...
by j_flanders
19 Dec 2019, 22:55
Forum: Modern Stompbox Effects (1975 - ...)
Topic: Dunlop JDF2 Fuzz Face [schematic]
Replies: 13
Views: 3285

Re: Dunlop JDF2 Fuzz Face [schematic]

Bside2234 wrote:
j_flanders wrote:Here's the correct schematic:
Which is what I have but the negative of C3 clearly goes to C5 on the PCB.
Correct, C3 neg to C5. Thanks.
Corrected my schematic:
Image
by j_flanders
19 Dec 2019, 17:20
Forum: Modern Stompbox Effects (1975 - ...)
Topic: Dunlop JDF2 Fuzz Face [schematic]
Replies: 13
Views: 3285

Re: Dunlop JDF2 Fuzz Face [schematic]

Here's the correct schematic:
Image
by j_flanders
19 Dec 2019, 16:56
Forum: Modern Stompbox Effects (1975 - ...)
Topic: Harley Benton - PA100 Power Attenuator [schematic]
Replies: 30
Views: 12808

Re: Attenuator broken?!? [schematic]

It's a Harley Benton Power Attenuator. In this web has a schmeatic: https://blog.brixit.nl/blog/2016/2/harley-benton-power-attenuator-measurement-and-teardown/ I measured all the amp inputs: 4Ohm: lpad min: 8.3R lpad max: 16.6R 8Ohm: lpad min: 12.3R lpad max: 20.6R 16Ohm: lpad min: 16.3R lpad max: ...
by j_flanders
06 Dec 2018, 00:40
Forum: Pimp-My-Cheap-Pedal
Topic: Behringer VM1 Vintage Time Machine
Replies: 107
Views: 58869

Re: Behringer VM1 Vintage Time Machine

Frequency reponse of the delay / feedback signal. Level and mix set for unity gain, feedback at 50%. In real life the signal coming out of the bbd section has been filtered by the anti-alias filter and the reconstruction filter, but to see the effect of the differences between the DMM and VM1 feedba...
by j_flanders
05 Dec 2018, 22:50
Forum: Pimp-My-Cheap-Pedal
Topic: Behringer VM1 Vintage Time Machine
Replies: 107
Views: 58869

Re: Behringer VM1 Vintage Time Machine

Some more frequency responses. The dry signal as it arrives after the compressor, just before the anti alias filter and the BBD section for the Deluxe memory man: (Level and mix is set for unity gain, feedback is at 50%) DMM_INPUT_TO_AAFILTER.jpg Same thing but for the VM1: The VM1 delivers a much m...
by j_flanders
12 Nov 2018, 20:25
Forum: Pimp-My-Cheap-Pedal
Topic: Behringer VM1 Vintage Time Machine
Replies: 107
Views: 58869

Re: Behringer VM1 Vintage Time Machine

Another correction for the schematic:
The overload circuit should come after the antialias filter, connected to the emitter instead of the base. Same goes for C54, but I posted that before.

Currently:
vm1-antialiaswrong.png
Corrected:
vm1-antialiascorrection.png
by j_flanders
11 Nov 2018, 17:32
Forum: Pimp-My-Cheap-Pedal
Topic: Behringer VM1 Vintage Time Machine
Replies: 107
Views: 58869

Re: Behringer VM1 Vintage Time Machine

I've found another error in the VM1 schematic, around c12 : Original: ScreenShot004.jpg Correction: C12-correction.jpg I also compared the anti-aliasing and reconstruction filters: I did this in the online Falstad web app: http://www.falstad.com/afilter/circuitjs.html?startCircuit=filt-hipass.txt Si...
by j_flanders
09 Nov 2018, 01:33
Forum: Pimp-My-Cheap-Pedal
Topic: Behringer VM1 Vintage Time Machine
Replies: 107
Views: 58869

Re: Behringer VM1 Vintage Time Machine

Maybe we need to retrace the vm1 in that location. I traced that part of the circuit and it confirmed that the VM1 schematic contains a mistake for c54 there. Instead of this: (eventually connecting to the base) ScreenShot006.jpg C54 should be connected to the emitter: ScreenShot005.jpg It's the Bo...
by j_flanders
08 Nov 2018, 22:03
Forum: Pimp-My-Cheap-Pedal
Topic: Behringer VM1 Vintage Time Machine
Replies: 107
Views: 58869

Re: Behringer VM1 Vintage Time Machine

I came across a schematic for the Boss DM2 and several sections looked very familiar. I started comparing those sections to the VM1 schematic and they're pretty much identical, part for part. So, the VM1 is a combination of the Deluxe Memory Man and the Boss DM2, we could call it the 'Memory Boss'. ...
by j_flanders
07 Nov 2018, 02:18
Forum: Pimp-My-Cheap-Pedal
Topic: Behringer VM1 Vintage Time Machine
Replies: 107
Views: 58869

Re: Behringer VM1 Vintage Time Machine

A few months ago I scored a used VM1 for 20 euros, looked like new. The 'playing a strat into an AC30' youtube video comparing it with a DMM sounded so promising. Mine sounded nothing like it, but I have no strat nor ac30 and all my guitars have rather hot and high output pickups. I greatly prefer m...
by j_flanders
07 Nov 2018, 02:14
Forum: Pimp-My-Cheap-Pedal
Topic: Behringer VM1 Vintage Time Machine
Replies: 107
Views: 58869

Re: Behringer VM1 Vintage Time Machine

Sorry to resurrect this thread, but this seems to be the definitive VM1 place on the web. What a great thread. It helped a lot. Many thanks for the excellent schematic! Here are my mods and fixes to the circuit: 1) Increase input impedance to 1M (see image below around UC3B) Added additional series ...