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Messages - joecool85

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Amplifier Discussion / Re: Accutronics Belton Reverb Module
« on: May 19, 2020, 09:37:06 AM »
Could you post a video or sound clip?  The Belton "brick" reverb can be a noisy thing, but not normally to the point of being bothersome.

Looks to me like a common TRS with cutouts.  Tip with cutout, ring with cutout, ground?sleeve.  Five terminals.

This was my thought as well.  I do agree with Phil though that matching it on the old PCB could be difficult as the pinout seems odd.  But point to point wiring on it should be straight forward enough.  Between a multimeter and spending some time tracing where the PCB connects which pin to what, you should be able to figure it out.

Does anyone have a schematic for this amp?  That could help as well.

Maybe something like this:

Alternatively, you could always do it without pcb or perfboard at all and simply point to point wire it.

Hi Phatt, that's a great start -- many thanks. I actually hadn't considered that the five wires might be anything other than signals from the two jacks but now you mention it...

Practically speaking, my options are i. to source exact replacement jacks and solder them to the sub-board and ii. to use standard jacks and  build my own sub-board from perf. Neither route is particularly easy. Any reason to choose one over the other apart from the non-issue of collectability/original condition?

Best, W.

Option 0, which should be tried first, is to clean the existing jacks.  Use some deoxit or similar, apply liberally to a 1/4" plug and work it in and out of the jacks for a dozen or more times.  Now try the amp.  If this doesn't fix it, you might need to replace the jacks.  They look like fairly standard PCB mounted jacks though.

Amplifier Discussion / Re: Gx-210 ultra twin mod ideas?
« on: May 18, 2020, 09:30:07 AM »
Also, you could run your effects board in the effects loop and just use your amp as a power amp.

Sent from my SM-G975U using Tapatalk

This is probably your best bet.  Typically poor amp sound, whether solid state or tube, comes from poor tone shaping in the preamp section.  Bypass this and you should be much better off.

Guitar News / Teisco coloring book challenge
« on: May 14, 2020, 01:48:50 PM »
Teisco has set up a coloring book challenge.  Download one of their pages, color it, upload to Instagram and caption your entry with the #myteiscopedal and tag Teisco at @weareteisco.  The winner takes home a Heritage H-150 Dirty Lemon Burst electric guitar! :dbtu:

The Newcomer's Forum / Re: Orange Crush 12 repair
« on: May 14, 2020, 12:47:45 PM »
You're right about cleaning up my soldering. Yes, its lead-free solder. And I will continue checking the ground connections.

Honestly, I would consider purchasing some leaded solder.  It makes repairs like this WAY easier.  Just wash your hands when done, and no licking the solder.   :dbtu:

The Newcomer's Forum / Re: Orange Crush 12 repair
« on: May 13, 2020, 02:24:49 PM »
No crackles when I wiggle any of the pots or jacks.
Joe, your mention of ground connections focused me. I think I soldered the overdrive pot, middle leg incorrectly to ground. See before and after photos below. What do you think?

Sent from my SM-A505FN using Tapatalk

Kinda rough soldering job on a few joints there.  I would suggest reheating any joints that don't look clean.  Are you using lead free solder?  If so, turn your heat up.  If not, you still may be running too cold, but just don't turn it up quite as high.

The Newcomer's Forum / Re: Newb here. I want to build an amp
« on: May 13, 2020, 07:45:26 AM »
Im done with the power amp section i bought a pbtl module for $3 it is a tda7293 100w module. Now im looking for a marshall sounding preamp. Ive been thinking of combining 3 circuits which is a Crunchbox, baxandall eq and cabsim. What do you all think?

Any reason for the cabsim?  Unless you are sending to headphones or direct out, I don't see the purpose.

The Newcomer's Forum / Re: Orange Crush 12 repair
« on: May 13, 2020, 07:43:57 AM »
1.At low levels, with overdrive at zero, a. Pretty good clean signal with a lot of hiss via internal speaker.
b. Signal disconnects intermittently when using headphones

Sent from my SM-A505FN using Tapatalk

Sounds like an intermittent ground issue.  Go over any solders/connections that go to ground.  Also, sometimes speaker outputs etc don't go direct to ground but rather pass through a 0.1 ohm resistor or similar.  If this is the case, you can cause issues by sending it straight to chassis with an uninsulated jack.

The Newcomer's Forum / Re: Newb here. I want to build an amp
« on: May 12, 2020, 10:37:01 AM »
So what chipamps are good nowadays?

Depends how big you want to go.  LM1875 is perfect for a small, but gig ready, practice amp (20-30w).  LM3886 is bigger (50-60w) and would work fine for most all gigging situations, but really overkill for at home.  Honestly I've been going the low wattage route lately as all of my playing is at home and I've found that 1/2w to 5w is the ideal for me.  More than that and I've got the amp turned just about all the way down so as not to bother the family.  You could check out the TDA7266M.  Maximum of 14watts at 18v supply.  12v supply will give about 7 watts.  This is plenty for practice and when wound up, it's going to be VERY loud still - especially with a good guitar speaker.

There are also class D amps, but these get a little more complicated in layout and design.


I am studying different preamp schematics. I am inclined to minimal amps or amps with not so many parts, just the ones needed to produce a given sound for guitar practice/bedroom playing purposes. I have several questions:

1.- Is it good to add a boost stage initially before any overdrive/soft clipping in terms of sound?
2.- Is it better to add a tone control stack before any clipping or after, in terms of sound?
Let's say you make: guitar, boost, tone control/tone stack, soft and/or hard clipping, out.
3.- Does it worth to add a classic tone stack with bass, trebble, mid respect a single pot tone control, or a BMP with some mid control (Jack Orman mod I believe...)?

It seems to me that with a simple tone control (or maybe two pots) you can get a wide range of sounds, but I am learning, and I would like to understand how many stages can have a guitar amp, and the purpose of those, to see how can I simplify or minimize them, and still get a good and wide range of sound. For instance, adding preamp stages to an LM386 can give you a good sound with control. I have tried hard clip diodes with a TL072, and the sound to me gets better. Nicer.

Thank you very much for your attention.

Regards, cheers.

For the ultimate in control of EQ and still simplicity, the two band Vox style works amazing well.  The great thing is even though it has no mid control, you can control mids by way of the treble and bass controls.  IE - you want very little mid scoop, set treble and bass to half.  Want a giant mid scoop, put the bass all the way up and treble matched (or a little down).  Check out the TSC calculators here:

When using the TSC calculators, I find it very helpful to click and drag on the graph to highlight from 82hz to 10,000hz as this is the guitar range.

You can do a lot with a modified BMP single tone control, but you are still locked into a certain type of sounds.  I've got one variant of it that will be going into the SSGuitar kit I'm putting together and it works quite well, but it is still limited compared to 2 band or 3 band EQ.

The Newcomer's Forum / Re: Randall rg80es red channel help
« on: May 12, 2020, 10:26:55 AM »
Thanks for the reply. I’ve tried this and the distortion still sounds very weak and saturated, I’ve even tried a 6 band eq still no big difference, the pull out treble knob does add a little extra, but still nothing compared to the sound clips I’ve seen of this amp.

Is it possible to do a quick video showing the issues?

The Newcomer's Forum / Re: Newb here. I want to build an amp
« on: May 11, 2020, 07:21:42 AM »
I want a preamp that is clean and pedal friendly for pedal testing purposes. And a tda2030 power amp with cd/aux input and emulated headphone out. I can read schematics but making it a pcb layout is hard to me. Can anybody help me.  :)

If you are planning on doing an actual PCB, I recommend doing the layout in KiCad.  It's open source, easy to use, and works super well.  Plus some vendors like OSHPark accept KiCad files natively.  If you want/need others, you can always output Gerbers.

Here is a set of videos I used when I was learning KiCad, they worked great:

I should note, not everything is 100% the same in the software since the video is 2 years old (some buttons have moved) but, it's close.

Amplifier Discussion / Re: Complete Rookie
« on: May 09, 2020, 07:06:13 AM »
For parts I always like talking to Steve at Small Bear Electronics:


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