Search found 204 matches

by george giblet
26 Oct 2020, 12:48
Forum: Pedal Debugging & Troubleshooting Support
Topic: Boss ODB-3 bass overdrive
Replies: 14
Views: 969

Re: Boss ODB-3 bass overdrive

Perhaps a slightly better or equal way is to add another 47k (tweak to taste) resistor just like R28 but on the other two terminal of the balance port. So add a 47k (or whatever) across the counter-clockwise and wiper terminals of the balance pot. The reason it might be slightly better is this set-u...
by george giblet
26 Oct 2020, 11:25
Forum: Pedal Debugging & Troubleshooting Support
Topic: Boss ODB-3 bass overdrive
Replies: 14
Views: 969

Re: Boss ODB-3 bass overdrive

i would like to see if there are any mods for the balance control circuit. The sweep on the control is strange ( distortion kicks in when the blend control is at 8-9 o'clock Is there a way to have it at 12 o'clock with equal levels between clean and distortion? I wonder if I can just replace the Bl...
by george giblet
25 Oct 2020, 07:51
Forum: Amplifiers
Topic: Alembic - SF-2
Replies: 16
Views: 6018

Re: Alembic - SF-2

State variable bandwidth isn't determined by Q. It's really not a bandpass filter. There's a band that gets passed, but the slope of the filter sections do not vary. Think of it more like 2 overlapping filters, rather than a single stage where the reactance/resistance ratio changes. Like 2 shelving...
by george giblet
23 Oct 2020, 15:24
Forum: Amplifiers
Topic: Alembic - SF-2
Replies: 16
Views: 6018

Re: Alembic - SF-2

It's going to be a state-variable filter for sure. It's going to be a second order filter for low-pass, high-pass *and* band-pass. The second order low-pass and high-pass are naturally 12db/oct The 6dB/oct band-pass doesn't make sense. The slope of a band-pass filter depends on the Q. If the Q is le...
by george giblet
22 Oct 2020, 11:09
Forum: Pedal Debugging & Troubleshooting Support
Topic: Boss ODB-3 bass overdrive
Replies: 14
Views: 969

Re: Boss ODB-3 bass overdrive

Frightening. And all this time you were thinking it's a stock unit.

The best thing about the problem is it has given you an opportunity to clean-up the mess.
by george giblet
21 Oct 2020, 09:14
Forum: Pedal Debugging & Troubleshooting Support
Topic: Boss ODB-3 bass overdrive
Replies: 14
Views: 969

Re: Boss ODB-3 bass overdrive

The 2x470pF caps to the switch are actually 2x220pF caps on most of the Boss pedals.
by george giblet
21 Oct 2020, 00:57
Forum: Pedal Debugging & Troubleshooting Support
Topic: Boss ODB-3 bass overdrive
Replies: 14
Views: 969

Re: Boss ODB-3 bass overdrive

There's no doubt it has the common two transistor flip-flop. Here's a good schematic (no diode in the emitters on the ODB-3). The ODB-3 is likely to have another the 1M, 47n cap, and Diode off the other collector [Warning: CE-2 uses the older flip-flip circuit. New ckt has no emitter diode and has 2...
by george giblet
16 Oct 2020, 03:41
Forum: Amplifiers
Topic: Laney LC50 Mk1 and Mk2 - B+ dropping resistor
Replies: 6
Views: 532

Re: Laney LC50 Mk1 and Mk2 - B+ dropping resistor

The calculations look OK. Since the ambient temperature in the amp is relatively high you would use a higher power resistor than calculated in order to get the same life as a resistor at room temperature. You already know a 3W resistor is starting to fail before the amp does.
by george giblet
12 Oct 2020, 11:32
Forum: Amplifiers
Topic: Laney LC50 Mk1 and Mk2 - B+ dropping resistor
Replies: 6
Views: 532

Re: Laney LC50 Mk1 and Mk2 - B+ dropping resistor

Drift isn't a good sign. I'd just replace it. All cheap parts.

There's some argument to use a 3W carbon comp as it will fail open if you get a PSU short.
A 5W is unlikely to fail.
by george giblet
18 Sep 2020, 03:33
Forum: Electric Guitar Rewiring
Topic: Ibanez GSR200 Onboard Bass Preamp
Replies: 3
Views: 6041

Re: Ibanez GSR200 Onboard Bass Preamp

It's part of a gyrator (IC1B, R6, R9, C8). It looks like a 1.0H inductor in series with 1k (R9) and in parallel with 2.2M (R6) For this circuit you can ignore the 2.2M part. What you have is a 1H inductor in series with 1k and that's in series with C7 (4.7uF) and the three elements form a series res...
by george giblet
07 Sep 2020, 23:04
Forum: Amplifiers
Topic: Peavey amp
Replies: 33
Views: 3025

Re: Peavey amp

I don't know what resistors or capacitors i would have to add or takeout to add the fx loop. You will need: 10uf electrolytic cap, 1M resistor, 47k resistor 2x 6.5mm Jacks, one with a normally closed switch contact. Using your VSS 20 schematic as reference, - Lift the negative terminal of C31 (2u2)...
by george giblet
07 Sep 2020, 00:00
Forum: Amplifiers
Topic: Peavey amp
Replies: 33
Views: 3025

Re: Peavey amp

Hey if I add a fx loop do u know were I would put it. After the post volume?
Checkout the Bandit 75 schematic, it actually has the FX loop.
by george giblet
06 Sep 2020, 00:10
Forum: Amplifiers
Topic: Peavey amp
Replies: 33
Views: 3025

Re: Peavey amp

It’s just weird why they would build a amp that u can’t have a tone stack on the gain channel. Don’t make no since. They could of least put a fx loop on it were u can run some kind of outboard eq. I suppose it all boils down to economy. The early 80's and 70's Peavey amps were mostly dual channel. ...
by george giblet
05 Sep 2020, 02:26
Forum: Amplifiers
Topic: Peavey amp
Replies: 33
Views: 3025

Re: Peavey amp

The other day played around with getting the Tone stack to have an effect in Gain mode. I tried a couple of things one was along the lines of tweaking the parts in the Supersat patent. A few conclusions we clear, 1) With the tone control it attenuates a good deal of the lower mids. 2) With the large...
by george giblet
02 Sep 2020, 05:05
Forum: Amplifiers
Topic: Peavey amp
Replies: 33
Views: 3025

Re: Peavey amp

Something occurred to me about the goal of getting a notched EQ. On the Peavey circuit the tone control is *before* the clipper, so even if we get the Tone control working in gain mode you probably won't get the notched sound you are looking for. For that you would need to add a notch circuit at the...
by george giblet
01 Sep 2020, 23:38
Forum: Amplifiers
Topic: Peavey amp
Replies: 33
Views: 3025

Re: Peavey amp

It’s a good amp got a good gain channel on it. Been nodding it to Try to get in the high gain territory. Sucks not having a tone stack on the gain channel can’t get a scooped sound. It should be possible to get the tone control in the signal chain. The problem is you want to get a scooped sound but...
by george giblet
31 Aug 2020, 06:03
Forum: Amplifiers
Topic: Peavey amp
Replies: 33
Views: 3025

Re: Peavey amp

I found some schematics of supersat era Peavey's. The two Audition schematics have the supersat-ish circuit but they don't have the switching or the 22k. The Bandit 75 is the Band in the supersat era. It has the 22k. (There is likely to be a Bandit 112 supersat after this model, I can't find the sch...
by george giblet
30 Aug 2020, 23:14
Forum: Amplifiers
Topic: Peavey amp
Replies: 33
Views: 3025

Re: Peavey amp

I haven't had a chance to look into this more deeply. The idea was to see what the manual said about the intended behaviour. Maybe it explains what it should do. From the manual, is the patent for the "Super Sat" circuit. It might explain some stuff. Normally values are given in the patent...
by george giblet
30 Aug 2020, 15:12
Forum: Amplifiers
Topic: Peavey amp
Replies: 33
Views: 3025

Re: Peavey amp

I notice that R27 is 22k,, holy crap man that will just kill the ability of tone controls. Well spotted. I don't get it. I've seen the C5+R7 thing before on Peavey amps and variations on other amps but I don't remember the low R27 thing. R27 is even a weird connection when SW1-B is to the left. Loo...
by george giblet
28 Aug 2020, 23:18
Forum: Amplifiers
Topic: Peavey amp
Replies: 33
Views: 3025

Re: Peavey amp

See discussion below and patent as this now seems incorrect - in fact it's opposite. Clean: SW1-A is open, SW1-B is to the right In clean mode the LEVEL pot is disconnect the U1A provides the gain control. The tone control operates normally. Gain: SW-1A is closed (9 to 11), and SW-1B is to left In g...