Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.

Messages - blackcorvo

Pages: 1 [2] 3 4 ... 8
I agree with Katoda, the plastic jacks are pretty good!

If you don't mind waiting, there are isolation washers you could try using for this:

If you'd rather not wait, or youc can't get that kind of washer, you could cut out a square in the chassis and use a plastic panel to mount the speaker-out jack to it. Or maybe a wooden panel, whatever fits the style of your build better.

R7 and C7 aren't mentioned anywhere in the schematic, my guess is that they used the same board for some other amp model, and added/removed components as needed for each model.

You mentioned having changed the bad pots, have you changed the volume one as well? If not, it might be also bad. If you did change it, check for possible DC leakage on C8 (470nF). Check DC voltage between the center lug of volume pot and ground when it's at the humming position. It should be under 1v, ideally 0v. If it's above that, change C8 for a new one and try again.
Since the issue is at the volume pot and nothing before it affects how it behaves, it's either AT the volume pot or RIGTH AFTER it.

Amplifier Discussion / Re: Vox Pathfinder 10 mods
« on: January 27, 2018, 03:15:10 PM »
Answering these, as I have some things to add to this topic. Thought it was better than making a whole new topic.

It's little confusing, does paralleling a 1M resistor to R7 has any effect or not ? (reducing gain when we are in overdrive channel)

Paralleling resistors makes the value lower. When they're the same value, you simply divide the value of the resistors by the number of resistors. So, 2 1M resistors would be, considering 1M as being 1000k ohms, 1000k / 2 = 500k.

Pot labeles on my amp are: B104 for gain,ALPHA B50Kohm for treble, A50Kohm for bass and ALPHA B50Kohm for volume. I think I need a log taper for volume,and since I can not find any log pots where I live, can I swap bass pot with volume pot ? (won't there be any problems with bass ? )

Yes, if you swap the Bass and Volume pots around you'll have better control over the Volume, but then you might not have great control over the Bass (or at least not as gradual). Try it out, worst case you'll have to swap the pots back.

Should I use anti log pot for gain ? if so,how can I change a linear pot to anti log ?

That's not necessary, the gain pot is pretty responsive as it is.


So, besides the responses, I just wanted to add to this topic by mentioning some mods I've done to my own Vox Pathfinder 10.

Here's the schematic with the mods:

So, what these mods have done for me:
- Changed C6 from 220n to 470n to up the bass response a bit, since I like using a treble booster with this amp;
- Removed the Red LEDs from the board and placed 2x White LEDs soldered directly onto R7, for a less harsh distortion even on "clean";
- Changed R8 to 100k, to get a bit more gain on "clean", which coupled with the White LEDs, sounds sweet;
- P3 was actually not a change due to seeking better tone, I bought this amp used and the Bass knob wasn't working, so I changed it with what I had at the time and never changed it back;
- Reducing R5 is just an alternative/suggestion to increasing R8, which I haven't tried (yet).

And here's a few sound samples of slightly different configurations. The guitar I'm using is a cheap SG copy with it's original pickups, and a self-made "Brian May Treble Booster" pushing the amp, all with the amp's overdrive switch On:

I'm really loving how it sounds now! Even without the treble booster, it sounds pretty sweet!

And here's the official page on the amp in Orange's website:

I just watched this and thought it would be well received here:

Orange finally delivers after this, ages ago:

What are your thoughts on this? I think it's a welcome change!

Tubes and Hybrids / Re: Peavey VTX Classic 212 65w Need Help???
« on: December 23, 2017, 06:48:02 AM »
Bquick, post your pics on IMGUR and paste the links to them here.
I didn't notice you were talking about the plastic covers on the caps having splits, my mistake! If it's just that, then yes, they are probably okay.
I'd still like to take a good look at the board myself.

Tubes and Hybrids / Re: Peavey VTX Classic 212 65w Need Help???
« on: December 22, 2017, 01:33:20 PM »

The large Caps on the power side have slight splits in the cover of the cap.  Other than that it looked okay. 

if by "splits" you mean something that looks like this:

Then congratulations, we found ONE issue! Those capacitors are definitely blown.
Now, we need to figure out what CAUSED them to blow, IF that's the case.

Pictures help greatly, if you could snap a couple and post 'em here. Both sides of the board, if possible.

Tubes and Hybrids / Re: LND150 tube emulator attempt.
« on: December 22, 2017, 01:24:36 PM »
You are right about twice the current of course, but there is not a wholotta current flowing there.
I did find out that when you put two diodes in parallel, the voltage drop across the pair is slightly smaller than across a single diode. Maybe that is good for something.
But actually, I think my problem is that I don't really understand the "grid" limiter thing of wich the diodes are part...

After reading on the link posted at the end of pg1 of this thread, what I understood is that the source diodes are there to help shape the clipping curve for the stage, as well as act like a protection circuit against overvoltage between source and gate. I might be mistaken, however.

The Newcomer's Forum / Re: Pot switch replacement on gorilla amp
« on: December 22, 2017, 12:56:09 PM »
Before trying to change the component, I'd squirt some contact cleaner into it and turn the pot up and down, to clean it. Then I'd run some compressed air into it to remove any residual dust, turn it again, and try to see if that fixes the noisy pot issue. If it didn't, only then i'd change the pot.

Anyways, here you go. Found something that's probably gonna be suitable to you:

I tried finding the closest to the one you have there, but I don't know if that style of potentiometer has a specific name. Closest I found were these:

Good luck!

Schematics and Layouts / Re: Randall Commander 1 (rg120-115)
« on: December 01, 2017, 02:31:58 PM »
There's this japanese website that increases the resolution of pictures (I guess it's one of those "machine learning algorithm" deals at work). Here's a link if you wanna check it out:

Attached goes the image after going throught the process, with 2x the original resolution. It's not perfect, but it makes it easier to see the traces, hopefully.

Tubes and Hybrids / Re: How hard is it to build the amp I want?
« on: December 01, 2017, 11:19:15 AM »
If you want to power the tube with high-voltage, there are these DC-DC Boost modules you can get for the job:
This one is a bit overkill at 40 watts of maximum output power, but you can probably find others more suitable to what you want to do. Or you could simply build one of those "nixie SMPS" with a 555 timer and a MOSFET.

For the power amp, you could try a Class D amplifier board. There's a lot of them to choose from, they're compact, they have A LOT of protection circuits built-in, and they can easily get pretty loud.
Here's an example of a cheap 30 Watt module board that works from 6 to 18 volts DC:

Amplifier Discussion / Re: Help with TDA2003 amp, a big project.
« on: December 01, 2017, 09:29:42 AM »
A 9v battery doesn't have enough capacity to power that amplifier, that's why it oscillated.

What you need is to connect the "negative" wire from the power supply to ground. Your power supply either uses one of those 2-prong outlet plugs, or the negative isn't grounded, to keep the 12v "floating" (aka isolated from ground references), which isn't something you really want for audio.

Either get a proper 12v 7Ah sealed battery for your tests, or find a way to ground the negative of your power supply.

Sorry, not loading here.

Sent from my XT1055 using Tapatalk

Here, try this:

The Newcomer's Forum / Re: Pignose 30/60 repair. help!
« on: August 31, 2016, 10:49:49 AM »
No need to hunt down the schematic, I already did:

Sending it as an attachment as well, just in case.  :dbtu:

It has the voltages on it, so I'd make a comparison between your amp's and the schematic's and make sure everything checks out.

Pages: 1 [2] 3 4 ... 8