Search found 3258 matches

by bajaman
23 Mar 2024, 23:51
Forum: Boutique Stompboxes dissected...
Topic: Tech21 SansAmp PSA-1 PCB traces and schematics [traced]
Replies: 69
Views: 80715

Re: Tech21 SansAmp PSA-1 PCB traces and schematics [traced]

I forgot to mention that I also changed the 4k7 connected to the wiper of the level control to 470 ohms (you could just use a link instead of a resistor) to allow lower settings of the output level ;-) . This pedal doesn't seem to have much drive compared to the sansamp classic, so I took a look at ...
by bajaman
23 Mar 2024, 02:59
Forum: Boutique Stompboxes dissected...
Topic: Tech21 SansAmp PSA-1 PCB traces and schematics [traced]
Replies: 69
Views: 80715

Re: Tech21 SansAmp PSA-1 PCB traces and schematics [traced]

okay - i made the changes based on the values that Stephanovitch advised, but, I did not like the result - it sounded too bright and harsh to my old ears so i had a good look at what av500 posted originally and the values of some of the other components used in my simulation and build. I discovered ...
by bajaman
21 Mar 2024, 20:10
Forum: Modern Stompbox Effects (1975 - ...)
Topic: Tech21 - SansAmp classic
Replies: 78
Views: 32857

Re: Tech21 - SansAmp classic

Thank you Stef ;-) (although the TLC2264 appears to be the wrong way around - pin 4 should go to OPA supply NOT Gnd)
cheers
bajaman
by bajaman
20 Mar 2024, 21:18
Forum: Boutique Stompboxes dissected...
Topic: Tech21 SansAmp PSA-1 PCB traces and schematics [traced]
Replies: 69
Views: 80715

Re: Tech21 SansAmp PSA-1 PCB traces and schematics [traced]

Thanks to Stephanovitch who supplied me with the correct capacitor values for four capacitors I had wrong: here are the amended response curves and amended schematic
cheers
bajaman
PSA1 graph of response to send all controls at halfway rev1.gif
complete rev1.png
by bajaman
20 Mar 2024, 10:27
Forum: Modern Stompbox Effects (1975 - ...)
Topic: Tech21 - SansAmp classic
Replies: 78
Views: 32857

Re: Tech21 - SansAmp classic

Wow thanks Stephanovitch The elusive sansamp classic is unmasked - I notice that the two resistors that attenuate after the gain stage are unmarked though ( the two in the bottom right of the picture) as i mentioned in my previous post I used 100k and 22k for these parts (the original Japanese poste...
by bajaman
18 Mar 2024, 00:01
Forum: Modern Stompbox Effects (1975 - ...)
Topic: Tech21 - SansAmp classic
Replies: 78
Views: 32857

Re: Tech21 - SansAmp classic

Another small update - on the original traced schematic attributed to an unknown Japanese author, there is a attenuator network after the amplifier drive stage opamp consisting of two 100k resistors. I changed the bottom leg to 22k to further attenuate the signal (the sansamp PSA-1 uses a 10k and 2k...
by bajaman
17 Mar 2024, 06:43
Forum: Boutique Stompboxes dissected...
Topic: Tech21 SansAmp PSA-1 PCB traces and schematics [traced]
Replies: 69
Views: 80715

Re: Tech21 SansAmp PSA-1 PCB traces and schematics [traced]

agung asked me what schematic I used to build my pedal version - this is a snippet i saved of the schematic i used in multisim (up to probe PR11)
It may be helpful for others so i am posting it here
cheers
bajaman
complete.png
by bajaman
16 Mar 2024, 23:31
Forum: Modern Stompbox Effects (1975 - ...)
Topic: Tech21 - SansAmp classic
Replies: 78
Views: 32857

Re: Tech21 - SansAmp classic

Okay - it is an old thread and even older design, but I thought I would have a go at building another one of these with a slightly different layout. i ended up using a TL072 followed by a MC33179 in my final build (images show MC33178 which did not work properly when engaging the low drive and clean...
by bajaman
13 Mar 2024, 07:49
Forum: Boutique Stompboxes dissected...
Topic: Tech21 SansAmp PSA-1 PCB traces and schematics [traced]
Replies: 69
Views: 80715

Re: Tech21 SansAmp PSA-1 PCB traces and schematics [traced]

Here is a graph showing the response after each opamp, from the first preamp gain stage up to the send socket. This is with all the controls set to midway - you can see the extent of the heavy low pass filtering involved in this design (PR1 to PR11) The left side shows the response in 3dB increments...
by bajaman
12 Mar 2024, 06:36
Forum: Boutique Stompboxes dissected...
Topic: Tech21 SansAmp PSA-1 PCB traces and schematics [traced]
Replies: 69
Views: 80715

Re: Tech21 SansAmp PSA-1 PCB traces and schematics [traced]

My simplified build in a Tayda 1590BB enclosure - Left out the extra line level input and took the output directly from the send. I had a stash of MC33179 quad opamps, so used them instead of TL074s - sounds good to my ears although i have never heard a real PSA-1 The sound is still there when the l...
by bajaman
23 Feb 2024, 23:48
Forum: Boutique Stompboxes dissected...
Topic: Tech21 SansAmp PSA-1 PCB traces and schematics [traced]
Replies: 69
Views: 80715

Re: Tech21 SansAmp PSA-1 PCB traces and schematics [traced]

There are still some wrong bits to the puzzle ;-) There is no 47n followed by a 100k to ground between U9a and U9b in the "secret" section - U9a output connects directly to U9b input ;-) I wonder what those 14 pin devices with the sanded tops are - they appear to be supplied by the +5 and ...
by bajaman
13 Feb 2024, 20:21
Forum: Boutique Stompboxes dissected...
Topic: Bogner - Harlow Compressor (gut shots) [traced]
Replies: 40
Views: 53879

Re: Bogner - Harlow Compressor (gut shots) [traced]

the turns ratio or impedance ratio of the transformer transformer still needs to be deciphered ;-)
excellent work
cheers
bajaman
by bajaman
13 Feb 2024, 09:54
Forum: Boutique Stompboxes dissected...
Topic: Bogner - Harlow Compressor (gut shots) [traced]
Replies: 40
Views: 53879

Re: Bogner - Harlow Compressor (gut shots) [traced]

The bjt transistors are most likely MMBT4401 type and the jfet MMBF5457
by bajaman
12 Feb 2024, 22:57
Forum: Boutique Stompboxes dissected...
Topic: Bogner - Harlow Compressor (gut shots) [traced]
Replies: 40
Views: 53879

Re: Bogner - Harlow Compressor (gut shots) [traced]

wow - excellent work here my guess is that the fet is a BF245A smd equivalent (https://www.onsemi.com/pdf/datasheet/bf245a-d.pdf) The vgs and idss fall into line with this device and it was the jfet used in the classic Urei 1176 studio compressor I would think any small signal NPN transistors with a...
by bajaman
24 Jan 2024, 06:58
Forum: Modern Stompbox Effects (1975 - ...)
Topic: Ibanez AD-80 issue
Replies: 2
Views: 503

Re: Ibanez AD-80 issue

I would check all the low voltage electrolytic capacitors - the 10v and 16v ones are prone to failure ;-)
by bajaman
18 Jan 2024, 10:37
Forum: DIY Projects
Topic: I can't find information about this blues driver anywhere
Replies: 5
Views: 836

Re: I can't find information about this blues driver anywhere

looks Russian - perhaps ask on a Russian site - definitely not a Boss pedal - lol
by bajaman
31 Dec 2023, 03:40
Forum: DIY Projects
Topic: Blue Pilot, an integrated Blues Driver
Replies: 18
Views: 5740

Re: Blue Pilot, an integrated Blues Driver

nice design Dylan ;-) I love the use of the gyrator to recover some bottom end which inevitably has to be reduced in drive pedals to prevent "farty" bass On the subject of the TL072, i have noticed some really bad crossover distortion in some I purchased from Ali-Express - moral: ALWAYS bu...
by bajaman
11 Dec 2023, 21:58
Forum: DIY Projects
Topic: Baja Presence and Resonance 091118 [documentation]
Replies: 44
Views: 47039

Re: Baja Presence and Resonance 091118 [documentation]

Hi and thanks for the question The Baja Reactor design was conceived a couple of months later than the Baja Presence and Resonance pedal and was an attempt to incorporate the actual vacuum tube power amplifier output stage into the mix. Yes, they are different implementations of the same basic idea ...
by bajaman
12 Nov 2023, 20:08
Forum: Pedal Debugging & Troubleshooting Support
Topic: Aion Oceanid (Cornish OC-1) Volume Problem
Replies: 4
Views: 712

Re: Aion Oceanid (Cornish OC-1) Volume Problem

all those voltages look ok to my eyes, so maybe a faulty resistor value - i would check R11 and R12 around IC1a - this seems the most likely place to start looking for increased gain
good luck
bajaman