JimRayden

Love the shape. Les Paul goes cubist.

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Jimbo

I was wondering if the gorgeus metal pickup cover fitted for a P-bass. I know there are also some specially made for a p-bass but the jazz bass ones are cheaper. Given the pickup differences, I'm suspecting they're quite different. Anyone tried?

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Jimbo

I wonder how the factory change will affect the quality...

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Jimbo

Oh goodie! I'm gonna be the first to buy this thingy.

And the next post is reply number 1000.

but I got POST number 1000

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Jimbo

Well, that means pre-filtering probably isn't going to do any good. Try adding a 10 ohm 1/2 watt resistor and a .047uF 25v cap in series between pins 4 and 5 (the Zobel network I was referring to earlier). It might also benefit you to bypass the power supply pin to ground with a 100uF or larger electrolytic (make sure you get the polarity right!) and a .1uF film or ceramic cap in parallel, as close as physically possible to the pin. Also try to make sure your driver cable doesn't come anywhere near the guitar electronics or the pickups - you're pumping 300 to 500mW to the driver coil, so it's going to be fairly easy to bleed a little signal back to the input, and it only takes a little to start oscillations. Sorry, but without seeing your setup, that's all I got, and those are at best "educated" guesses. Anyway, maybe some combination of the above will be a solution. 

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I copied this post to my notepad and am starting to try the tricks right away.

I think the major problem is that my driver wire goes with all the wires and even passes the bridge pickup. I'll try taking the wire externally. The guitar will look like Civil War afterwards but at least it'll be working. Oh boy, here's my chance to use duct tape on my guitar. (I've always wanted to have a reason for that. )

Thanks to you too, Pete. Too bad that your posts are too long to post. But I'm certainly taking notes from all of them.

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Jimbo

Lovekraft, in harmonic mode, I get high pitched oscillation, yes. In normal mode, i get low pitched buzzing oscillation. Or was it vice versa...

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Jimbo

So yea, I built it like HB -> Sparkle boost -> poweramp of Ruby. I must say, I'm getting some good stuff going on now.

I have the sustain control between the boost and the 386 section, with the Sparkle gain hard wired to max. One bad though... I can only turn the sustain knob up to the limit of infinite feedback. If I get too much further than that, it starts oscillating. I see two solutions: either try to trim the gains of Sparkle boost and poweramp to the optimal clipping/power balance, or totally isolate the sustainer circuirity from the signal one. What would stop the oscillation? I need to start working on it because we're hitting a studio in a few weeks and I'd be really happy to complete this gadget before that.

The good news are that it looks very promising as it is.

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Jimbo

Now, Pete mentioned something about having a different preamp for his 386 amp for more gain. I'm still not getting satisfactory results but I'm getting closer and closer. I thought of rising gain capability on the Ruby. How to do that, what resistors to swap?

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Jimbo

Wouldn't the circuit's input impedance connected in parallel with the pickup interfere with something?... I mean, that would have the effect of non-true bypass switching.

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Jimbo

BTW, you need some kind of a buffer to send one pickup's signal to the Ruby and output?

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Jimbo

The coils go the same way, the magnetic polarity is different.

That's what I know at least.

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Jimbo

Alright, news. Went out and bought 0,2mm wire. Oh joy, it works better on low strings and does its thing on highs too. But it does it weak. The strings sustain but still don't pass the infinity mark. Maybe it's because I'm using 1/2 of a humbucker to drive the ruby. Does that give too little output? I don't think so...

It could also be because I'm using rather long wires to connect pots, jack, perfboard, the driver, etc.

What do you think?

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Jimbo

Thanks, Digideus. I'll run the wire from the bridge pickup.

Thanks Drak, I'm not a lightning bolt type of player. I'm more of a wire-through-bridge-pickup-ring type of guitarist.

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Jimbo

Of course, the other choice is take the wire there externally. I think I'll do that since my guitar's external looks messed up enough already (because of many attempts to install the sustainer. )

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Jimbo

The grounding wire of TOM bridge of my ESP broke off. Will I have to take out the mounting... things... I don't know what you call them. You know the things that are placed in the hole in wood to screw the TOM into. It's lots of work but I don't see any other way.

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Jimbo

Oops, I ment the Gibson 335.

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Jimbo

The cutaways look alot like a 535. I can't express how much I love the shape/color on this thing. Indeed, as someone said, there still are classic shapes out there to be invented. I might get inspiration for my next guitar here.

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Jimbo

I had the same results with 0.3 mm wire, bad to no response on the high e. that was only a 4 ohm coil too. My guess is the ohmage mostly influences the power of the driver (8 ohm being more efficient with the lm 386), while wire diameter tailors frequency response. That 0.2 mm diameter seems to be pretty crucial.

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Your experience with 0.3mm looks like a success compared to mine. You had a bad working high E. I have a bad working LOW E with other strings not working at all! What else could be wrong besides the wire?

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Jimbo

It's not working out! I have to turn the driver 90 degrees from it's normal position and place it really close to the low E string to get ANY sustain on the string. I smell a serious lack of efficiency here.

It's not about fun anymore. It's all blood, sweat and tears.

Ok ok it's not that bad, I just couldn't realise that getting audible results would be that difficult.

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Jimbo

Here's the answer to your prayers. I actually got the idea from this thread and thought to help out.

http://projectguitar.ibforums.com/index.php?showtopic=18075

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Jimbo

Thanks for the graph, finnish friend.

Ok, the graph tells me that with my thinner wire I'm having 2 times less turns than it would be with 0,2mm. My question is - is that what's wrong with my driver? Is the number of turns that important? Maybe I should wind the thing up to 16 ohms and hope for the amp to work without significant loss of volume. Yea I think I'll go and try it out right now.

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Jimbo

Ok, I also tried the thin wire with the single coil but it didn't work out either. Seems like 8 ohms of the thin wire is not enough turns to drive the strings... I think I'm going back to 0.3 wire, to at least drive the bottom strings.

Where the heck is the edit button? No wonder this thread is 65 pages.

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Jimbo

i've been thinking about this a lot lately.  here's a chance for one of you tube amp gurus not only to go down in history but to make a little money while you're at it. 

when i first got interested in repairing and building tube amps i bought several books on the subject.  with no electronics background other than repairing and custom wiring guitars i started with an old navy basic electronics book that did an admirable job of explaining tubes and how they worked.  i added "how to service your own tube amp", by tom mitchell, "the tube amp book" and a great little book titled, "how to test everything electronic."  there were a couple more that i don't see right now but the point is that i read everything i could, bugged the devil out of you guys, thoroughly investigated every other site that i could find and even bought a couple of tapes.

i can now do a reasonable job of fixin' them and haven't had a problem yet that i couldn't repair but during the entire process the one thing i found in common with all of the books, tapes and tutorials is that they assumed knowledge that wasn't there.  things like where exactly to check b+ power, what a coupling capacitor is and does and where it is in the circuit, how to test a power transformer in and out of the chassis. things that are basic to a lot of you but were greek to me.

i would have loved to see a fairly simple layout of say a fender bassman, for instance, with arrows pointing to various components and explaining what they do, how they effect input, output or whatever.  a step by step troubleshooting guide with arrows pointing to the exact place to put the positive probe on your multimeter when you're checking bias.  i'll admit that i still don't know for sure what all of the caps and resistors do and how changing their values would effect the  operation and/or sound of an amp.  i can test them and replace them if they're bad but what do they do?

anyway, you get the point.  if one of you wanted to be a real hero and get some serious mailbox money commin' in you could take all the spare time you have  for the next three or four years and write the definitive text on learning how to be an amp tech with no experience necessary.  i'd still buy the first copy and all you have to do is make a small mention somewhere in the book that it was my idea.

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Ay for that. I'd be the second to buy that book.

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Jimbo

Argh, I rewound it to a 4mm deep coil. The wire is actually a bit thicker than 0,16mm. My single coil with 0,3mm wire at least worked on the lower strings. The newest driver seems to work on all the strings equally but it's less efficient.

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Jimbo

Hmm... The last one with finer wire is the least efficient of them all. It doesn't seem to even pass the "endless feedback" mark. It does seem to make the note stand longer but it doesn't turn into harmonics and the cool stuff. Not even in the harmonics mode...

I got 10 ohms of about 0.16mm wire, potted, with about 5mm wide, 3mm deep core. I can't see that huge of a difference to make it less unefficient than my previous attempts...

Oh help me, the harmonics in my head are getting stronger!

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Jimbo