Blues Deluxe to ODS #183 Thread

[norburybrook]

the best solution I've found is a wet/dry, where you take the signal from your ODS pre out into a fully wet set of FX and then into another amp. Keeps your ODS clean and you can adjust your FX level with a volume pedal. In the studio I always record straight into the amp and apply time based FX afterwards.

I still think the Dumbleator is the way to go if you're using the passive FX loop on an ODS and don't want to do wet/dry. Even Larry Carlton has come back to that way of thinking


All good for discussion though and everyone has their own way I mean Robben has now gone to using a pedal for his OD so he can use time based FX in front of his ODS!! go figure


M

[pompeiisneaks]

Ok so I had a buddy play for me on the demo last night and the amp did great. Until we got to his single coil guitars. Then if the amp was on OD, and the bright or brighter switch were engaged we got the horrid squealing again. At least I know 'how' to reproduce it now. What would cause the OD to squeal only with a bright cap in the signal path? Is it just having too much high end? Should I trim down the 'treble' pot on the HRM until it subsides or just not use the bright with single coils?

Odd one. Not sure I've ever heard or read anything on something like this myself. Tapping the caps with a chopstick when squealing didn't change it at all.

I've got the raw audio if I can get around to it later, I'll pull out a bit of it for those that want to hear it

~Phil

[JazzGuitarGimp]

Hi Phil.

How long are the wires between the bright switch and the board? Shielded, or unshielded?

Thanks,
Lou

[xtian]

Silver mica and ceramic caps can be microphonic. But tapping on it should be revealing, as you suggest.

[pompeiisneaks]

Hi Phil.

How long are the wires between the bright switch and the board? Shielded, or unshielded?

Thanks,
Lou

Unshielded, I think they're very close, here's a shot, less than half an inch I'd say?

brightswitch.png

~Phil

[pompeiisneaks]

Silver mica and ceramic caps can be microphonic. But tapping on it should be revealing, as you suggest.

Yeah that's why I tapped them, to see, but didn't get a specific problem on either. also it's BOTH of the ceramic's doing the noise, not just one. Could it be a switch issue?

~Phil

[JazzGuitarGimp]

Hi Phil,

Looking at your pictures, I see a few things:
- R51 should be 100K, it looks like you’ve got 4.75K in there? Am I reading that right? EDIT: I am not seeing R52 in the pictures, but that is the one that should be 4.75K - is it possible you swapped the value of these two parts?
- the global negative feedback connection should come from the 4-ohm OT tap, which I believe is the GRN/YEL wire. It looks like you are connected to the 8-ohm tap (GRN wire).

Correcting these might help a bit.

Cheers,
Lou

[pompeiisneaks]

Hi Phil,

Looking at your pictures, I see a few things:
- R51 should be 100K, it looks like you’ve got 4.75K in there? Am I reading that right? EDIT: I am not seeing R52 in the pictures, but that is the one that should be 4.75K - is it possible you swapped the value of these two parts?
- the global negative feedback connection should come from the 4-ohm OT tap, which I believe is the GRN/YEL wire. It looks like you are connected to the 8-ohm tap (GRN wire).

Correcting these might help a bit.

Cheers,
Lou

I'd have to peek again, but the negative feedback tap is a grey wire coming directly off of the socket that was the one set by the previous amp (I am wondering if there are more than a few things different for this amp vs the hot rod deluxe)

I'll look at the values you've set, but it "IS" possible I have bad values for negative feedback since the one I was copying it from was EL34's and these are 6L6's/5881's (the latter in this case). I just copied the values from the #183 everywhere I felt I could with exceptions like the HRM because it doesn't exist in the #183 etc.

Is the theory you have there that my negative feedback is set wrong due to the value I used and maybe I've got oscillations due to that?

In the #183 he used 4.7k negative feedback, and that's what I used. I also used a 2.2k presence pot, a 1uF tantalum cap for that part etc.

If I need to swap that out due to being wrong for the tubes I can

Which now leads me to another value I didn't think of, the grid stoppers, I used the 5.6k for my 5881's is that too much? I don't hear any problems on the clean side, it sounds great to me (and my buddy that was playing it) and he and I love the drive but it just has that odd oscilation, (which does make me think maybe my NFB resistor may be too low and causing problems? Not sure though, I'd almost think too much negative feedback would just dampen things, not add oscillations no?)

R52 is 390 ohm on the LTPI in the #183 as well.

Both of these values are 'right' for the #183, but now I'm questioning R51. I know the tail resistor is fine, as that's just for the specific values of the LTPI, but R52 maybe does need a change? (BTW the 4 ohm tap is on the board in the Blues Deluxe but I think they just connect it to a non used tab to keep it 'safe' I've just shrink tubed it off and have it down in the chassis near the output area. I'm not using it.)

~Phil

[JazzGuitarGimp]

Ah, okay - it had slipped my mind that you were building a 183. I think I would leave your NFB circuit as-is for the time being, and look elsewhere for the oscillation. A few questions / suggestions:

- When the oscillation occurs, can you affect it’s frequency by changing the positions of the volume, tone, and pickup selector controls on the guitar, without changing any of amp’s controls?

- Are you using a good-quality cable to connect the guitar to the amp?

- Does moving the guitar as far away from the amp as the cable will allow change the oscillation?

- Have you tried setting the controls to the point where feedback begins, and then push the chassis wires around with a chopstick?

- Have you tried it with the amp completely closed up (I am assuming the amp has a sheet of foil on the inside of the back panel that comes into contact with the chassis flanges to shield the circuitry...)?

We’ll get this figured out...

Cheers,
Lou

[pompeiisneaks]

Ah, okay - it had slipped my mind that you were building a 183. I think I would leave your NFB circuit as-is for the time being, and look elsewhere for the oscillation. A few questions / suggestions:

- When the oscillation occurs, can you affect it’s frequency by changing the positions of the volume, tone, and pickup selector controls on the guitar, without changing any of amp’s controls?

- Are you using a good-quality cable to connect the guitar to the amp?

- Does moving the guitar as far away from the amp as the cable will allow change the oscillation?

- Have you tried setting the controls to the point where feedback begins, and then push the chassis wires around with a chopstick?

- Have you tried it with the amp completely closed up (I am assuming the amp has a sheet of foil on the inside of the back panel that comes into contact with the chassis flanges to shield the circuitry...)?

We’ll get this figured out...

Cheers,
Lou

I've tried some of them, I can't recall right now all, I can try to reproduce today and see what I get. I didn't have the chassis cover on it, though, so with LED lights, and an open back and being relatively close to the amp may all be components of this yes. I'll see what I find. (I think I recall the treble pot especially muting it a bit if you dialed it down, but never removing it But I'll test and see.)

~Phil

[pompeiisneaks]

Of course I now can't get it to do it. I used MY tele, single coils too, and have it at almost max master volume and max drive volume and drive. it's pure beef, love it. NO oscillations, but great feedback etc.

clueless.

also I must have wired something wrong with my effects loop jacks. If I plug anything into them there's no sound. /sigh. Not sure what I did there. Oddly yesterday with my reverb pedal in the loop, with it 'off' signal went through just fine, but with it on I had nothing. Now with my effects loop through my tuner, delay and reverb, I get nothing will all off or any one of them on etc.

not sure what's up there.

Edit: THOUGH I did use a different cord, the back is on and I'm not downstairs in the kitchen directly below LED's so maybe it's one or all of the listed possible issues? Yes there's a kind of metal tape on the inside of the panel to create a full shield for the chassis.

~Phil

[norburybrook]

Phil,

its possible your friends Single coils weren't potted, or not potted very heavily so it was quite microphionic . Your guitar may have more wax or whatever potting and therefore be less microphonic.



just a thought


M

[pompeiisneaks]

Phil,

its possible your friends Single coils weren't potted, or not potted very heavily so it was quite microphionic . Your guitar may have more wax or whatever potting and therefore be less microphonic.



just a thought


M

hmm yeah that's possible, he was using a warmoth parts tele, and had a fender HSS strat using single coils as well, but the strat I think were some nicer brand I can't remember.

I also did note that my other cable, albeit nice, did have an odd thing, it's a monster cable, but the tip of the tip sleeve part on one end seems to spin freely. I'm guessing it probably doesn't matter as under pressure in a jack it gets forced back into the base, and I'd also get like (0) signal through with a broken signal cable, but maybe that is still allowing for some noise to come in as well?

~Phil

[norburybrook]

Phil,

its possible your friends Single coils weren't potted, or not potted very heavily so it was quite microphionic . Your guitar may have more wax or whatever potting and therefore be less microphonic.



just a thought


M

hmm yeah that's possible, he was using a warmoth parts tele, and had a fender HSS strat using single coils as well, but the strat I think were some nicer brand I can't remember.

I also did note that my other cable, albeit nice, did have an odd thing, it's a monster cable, but the tip of the tip sleeve part on one end seems to spin freely. I'm guessing it probably doesn't matter as under pressure in a jack it gets forced back into the base, and I'd also get like (0) signal through with a broken signal cable, but maybe that is still allowing for some noise to come in as well?

~Phil

un potted pickups ONLY tend to come from the higher end boutique makers as they're a handful at times because of things like this so mainstream manufacturers always tend to er on the side of caution and pot pickups well.


M

[pompeiisneaks]

Phil,

its possible your friends Single coils weren't potted, or not potted very heavily so it was quite microphionic . Your guitar may have more wax or whatever potting and therefore be less microphonic.



just a thought


M

hmm yeah that's possible, he was using a warmoth parts tele, and had a fender HSS strat using single coils as well, but the strat I think were some nicer brand I can't remember.

I also did note that my other cable, albeit nice, did have an odd thing, it's a monster cable, but the tip of the tip sleeve part on one end seems to spin freely. I'm guessing it probably doesn't matter as under pressure in a jack it gets forced back into the base, and I'd also get like (0) signal through with a broken signal cable, but maybe that is still allowing for some noise to come in as well?

~Phil

un potted pickups ONLY tend to come from the higher end boutique makers as they're a handful at times because of things like this so mainstream manufacturers always tend to er on the side of caution and pot pickups well.


M

Oh interesting... hmm. I may have to ask him about that. He did say I think both were fancier pickups and he was thinking of reverting to fender stock on the HSS Strat.

~Phil