Search found 1025 matches

by phatt
07 Mar 2024, 12:10
Forum: Amplifiers
Topic: Single ended tone control question
Replies: 7
Views: 745

Re: Single ended tone control question

It's a passive top cut filter across the signal path, look at the top cut tone in a Vox AC 30 same trick just done on the output side.
Phil.
by phatt
06 Feb 2024, 11:51
Forum: Amplifiers
Topic: Need help with peavey bandit 112 volume problem
Replies: 4
Views: 1366

Re: Need help with peavey bandit 112 volume problem

Some tecks will likely frown on me for this but I have used WD40 or RP7 many times to un-scratch pots with no issues. My 40 Yr old Tandy Receiver had a dying volume pot with bad intermittent static on rotation,, and was going to be a nightmare open heart surgery to replace it. so 1 squirt of WD40 an...
by phatt
20 Jan 2024, 07:57
Forum: Amplifiers
Topic: Noisy solid state preamp's (ROG, etc)
Replies: 7
Views: 910

Re: Noisy solid state preamp's (ROG, etc)

issues that I've missed. You've missed the fact that the biasing resistor has nothing to do with setting the gain of a noninverting op amp, and that impedance in parallel with the input doesn't add to Johnson noise, so your entire premise is false. [smilie=a_whyme.gif] Seems there is a understandin...
by phatt
19 Jan 2024, 05:34
Forum: Amplifiers
Topic: Noisy solid state preamp's (ROG, etc)
Replies: 7
Views: 910

Re: Noisy solid state preamp's (ROG, etc)

NOISE is your Enemy when designing high gain dirt circuits, Not just ROG but many others suffer the same fate. It's not the fault of the active components in these circuits It's the combination of having many hi Z sections all joined up. Go look at the first stage of a TS9 or similar schematic. They...
by phatt
31 Aug 2023, 10:44
Forum: DIY Projects
Topic: 2CH Mixer audio Op amp voltage sum + buffer
Replies: 13
Views: 1292

Re: 2CH Mixer audio Op amp voltage sum + buffer

FiveeveN has linked to the answer, wise to read it.... But I assume your having trouble working out how to run this on a single supply? I'm adding a quick edit of Rods circuit which should help. Everything in between the input Caps and output cap runs at Virtual Common or Half supply. Caps are likel...
by phatt
01 Aug 2023, 04:05
Forum: Pedal Debugging & Troubleshooting Support
Topic: Ibanez sc10 pedal poping noise
Replies: 3
Views: 468

Re: Ibanez sc10 pedal poping noise

Does turning the speed knob effect the speed of the ticking?
Phil.
by phatt
23 Jul 2023, 22:49
Forum: Pedal Debugging & Troubleshooting Support
Topic: AMZ Buffer Module
Replies: 2
Views: 512

Re: AMZ Buffer Module

Thanks Mr 57, Brilliant explanation, Wish I knew this years ago. :thumbsup
Phil.
by phatt
24 May 2023, 21:57
Forum: Pedal Debugging & Troubleshooting Support
Topic: Octavius kit from pcb mania
Replies: 12
Views: 1098

Re: Octavius kit from pcb mania

Maybe check that Transformer, I can't see enough but it looks like the Tx has 6 leads and the back of the PCB shows all 6 soldered.
The center lead on the primary should be left open, (as per schematic) if it's grounded them you would loose a lot of volume.
Phil.
by phatt
19 Apr 2023, 00:29
Forum: Pedal Debugging & Troubleshooting Support
Topic: Grounding Issue for DIY pedalboard
Replies: 7
Views: 832

Re: Grounding Issue for DIY pedalboard

Have you tried this yet?

Common (neg of your 9V pedal PSU) goes to the MAINS EARTH terminal.
Do not rely on alloy case for ground return.
Phil
by phatt
18 Apr 2023, 00:19
Forum: Amplifiers
Topic: Traynor YVM-1 Issues
Replies: 7
Views: 1228

Re: Ammo Can Reactive Load

Oh dear :shock: Well if there is that much damage then for sure you have carbon particles all around that area which could well be creating a pathway for the hi voltage to trace through. Sounds like you will be forced to rebuild the Board if you want it to be reliable. :( This is why you see flame p...
by phatt
17 Apr 2023, 04:11
Forum: Amplifiers
Topic: Traynor YVM-1 Issues
Replies: 7
Views: 1228

Re: Ammo Can Reactive Load

Remember electrons flow to the Highest voltage potential. :hmmm: Any power Valve would burn through the screen rapidly if the Plate voltage ever falls lower than Screen voltage. As the amp is old the plate pin might be arcing across the socket somewhere which will pull plate voltage down. And I woul...
by phatt
16 Apr 2023, 23:23
Forum: Amplifiers
Topic: Traynor YVM-1 Issues
Replies: 7
Views: 1228

Re: Ammo Can Reactive Load

Oh dear, As the Amp has already had Screen grid issues then the sockets may have hair line carbon traces (which you can't see) and once that happens it's likely the new tubes will arc again along the same path, in which case it's a Socket replacement. Also worth note is that EL34's are notorious for...
by phatt
14 Apr 2023, 11:27
Forum: Pedal Debugging & Troubleshooting Support
Topic: Grounding Issue for DIY pedalboard
Replies: 7
Views: 832

Re: Grounding Issue for DIY pedalboard

If you are going to run mains to a metal case (your module one I presume) Then For safety reasons alone you definitely need to tie the mains earth to that metal case otherwise it could be deadly if something goes wrong. :twisted: As *mauman* already noted, post a layout or picture of the setup as th...
by phatt
16 Feb 2023, 10:21
Forum: DIY Projects
Topic: Switchable PS
Replies: 10
Views: 1031

Re: Switchable PS

Hi Kiltro, An LM7809 would have no trouble dropping 9volts, They are rated up to 1Amp. FWIW, I use a Laptop power supply which delivers 19VDC at 4Amp and then use an LM7809 for the lower voltage pedals. IIRC I just added a series 220R resistor before the Reg chip and a small heat sink to be on the s...
by phatt
17 Dec 2022, 10:42
Forum: Modern Stompbox Effects (1975 - ...)
Topic: Caline CP-29 White Heat [schematic]
Replies: 31
Views: 8743

Re: Caline CP-29 White Heat [schematic]

Thanks phatt, excellent info. I think the pulldown resistor in the input is just to stop the switch from clicking from capacitive buildup of voltage since the LED is also going through it, or maybe backwards charge potential on the input cap, I remember popping being some issue with it. Yes R1 is j...
by phatt
16 Dec 2022, 13:42
Forum: Modern Stompbox Effects (1975 - ...)
Topic: Caline CP-29 White Heat [schematic]
Replies: 31
Views: 8743

Re: Caline CP-29 White Heat [schematic]

Glad to hear it helps you Manfred, The sensitivity of the input is the issue. Remove R1 as it's likely irrelevant,, R2 is the dominant load. Try looking at it this way. As *mictester* noted the input Z is way too low to be useful for guitar. OK you change R2 to 1Meg and you raise the input sensitivi...
by phatt
16 Dec 2022, 03:27
Forum: Modern Stompbox Effects (1975 - ...)
Topic: Caline CP-29 White Heat [schematic]
Replies: 31
Views: 8743

Re: Caline CP-29 White Heat [schematic]

My only issue(s) with this design is that I would have made R2 a larger value, to raise the input impedance to prevent loading on either the previous effect or the guitar pickup. I've also been wary of exposing op-amp FET inputs to the outside world - they can be more susceptible to static than a s...
by phatt
07 Dec 2022, 11:11
Forum: Pimp-My-Cheap-Pedal
Topic: Rat mod to improved clean up tome when riding guitar volume?
Replies: 8
Views: 2120

Re: Rat mod to improved clean up tome when riding guitar volume?

As you have built some Rat circuits, I would try putting a simple buffer in front. Just look at Tube screamer for clues. Or as mentioned, try another opamp. As for the guitar treble bleed trick yes it can help but there are other things you could try. I swap the tone side of my Strat switches which ...
by phatt
01 Oct 2022, 00:25
Forum: Boutique Stompboxes dissected...
Topic: Rockman Ultimatum Distortion Generator Pedal [Traced]
Replies: 9
Views: 2305

Re: Rockman Ultimatum Distortion Generator Pedal [Traced]

I see it drawn as a Variable Resistor and as such it would effect the output volume, at least down to the value of R22 If If pin 1 was grounded (bypassing R22) then at zero the output would be nil, a dead short across the signal path = no sound. I've seen this Variable Resistor idea used as Volume c...
by phatt
26 Sep 2022, 02:48
Forum: Pedal Debugging & Troubleshooting Support
Topic: need help reparing ammoon looper sudden death [SOLVED]
Replies: 5
Views: 1670

Re: need help reparing ammoon looper sudden death [SOLVED]

No, it's a fair bet it's just a silicon diode used for reversed polarity protection.
D4 most likely blew because some one used a reversed plug supply. opps