JohnH

I have one concern with this (not sure if it is a problem). A normal metal jack socket has its ground connection in contact with whatever chassis it is mounted on. The output from the amp may be to two ends of a transformer, and not intended to be grounded? If this is a concern - use a plastic jack socket, as on Marshalls. John

One thing that is true of all guitar cables is that the shorter they are, the better at preserving the high end of your sound. The cables have capacitance, which acts like a treble cut. Shorter cables have less of this. John

Hi Tom (and G'Day Unk, nice to see you out and about on the I'Net) I have a DSL401, it should be: very quiet with no input plugged in, even if volume turned up Good bass on clean channel - with a very clear vibrant sound OD channels are somewhat lacking in bass, particularly with the stock speaker (a Vintage 30 is much better), unless you turn up the gain. Its voiced to make screaming Marshall lead tones If you are getting swoshing, even with master volume at zero, something in the output stage must be amiss. And Unk is not joking. There's hundreds of volts inside, that can hang around in capacitors even when unplugged. As they would say in German (if they didnt speak German): "Achtung!...Das machinen ist nicht fur gefinger poken!!" John

You mean an "apparent boost", or resonant peak, right? Since a passive filter can only attenuate, there's never a boost without a battery. Surprisingly, it can really be a boost - and theres no rules of physics broken here! The capacitor and the inductance of the pups form a resonant circuit at a frequency dependent on their values. Responce at this frequency is greater, after which it falls sharply at higher frequencies. This is a voltage boost - of course there is no power boost (that would defy energy conservation), but it is voltage that the amp is reacting to, so you get a greater signal at this fequency. There are lots of mechanical analogies where putting a small input into a spring/mass system, at the resonant frequency, causes a larger response- which builds up over several cycles. Who ever bounced up and down on a car with no shock absorbers? John

I find normal tone controls make too much dullness, but a choice of very small caps from 1nF up to say 10ny is very useful. You get a high cut, but with a boost at the frequencies just below - really changing the voice of the guitar, not just dulling the treble John

I did this on some open coil humbuckers, and made a step by step record. take a look, it may help you: http://au.geocities.com/guitarcircuits/fou...rconductor.html good luck! John

I prefer not to solder to the back of pots. I solder a bare wire to a washer which goes over the pot shaft and gets clamped between pot and pickguard. This wire then loops back to the ground lug on the pot, and all other grounds attach to it. It saves having to heat up a pot case sufficiently to melt solder. John

Heres my guess, and it is just a guess - others please point out if it does not make sense. It sounds like your power supply works fine with this pedal on its own, but not with other pedals as well. That shows that the polarity of the supply and the pedal are compatible, ie, most probably the outer barrel of the power supply plug is positive and the inner negative? - which I believe is as for most pedals. It could well be that the signal ground connection (ie the wires that connect to the outer sleeve of the guitar cord and patch leads) is positive in this pedal and negative in the other pedals. Plugging two such different pedals into one power supply would connect positive to ground on one pedal and negative to ground on the other, hence shorting the power supply. If that is true, then a second power supply or batteries may be the easist answer, since the problem is inherent in the design. Such a grounding arrangement I have seen on designs for classic old-style fuzz boxes using Germanium transistors. Is that what this is? cheers John

Hi Mingus - Im in NSW. and couldn;t find those switches in Oz either. But you can get them at mouser in the US, heres the product link: http://www.mouser.com/index.cfm?handler=di...e_pcodeid=01019 I have one on each pup of my LP. they are a well made switch. John

Over at Guitarnuts2, we have thread happening on this subject: http://guitarnuts2.proboards45.com/index.c...read=1144936220 John

So how do you wire the dummy coil? I would expect that it would go in series with the others, say between the pups and the volume control. Then, assuming the pups are wired normally, with paralel combos, it should do a fairly good job of cancelling noise in all positions. But how are these coils normally connected? John

If you are getting into cab building - here are the plans for the mighty Marshall 1960 4x12 slant cab http://www.18watt.com/Storage/1960A-Slant-Cab_rev1.pdf The cosmetics of a cab look like the hardest part - but that is your choice as to what you want. The technical part of building a cab that works as well as any other is just basic carpentry. John

Ive have recently bought a secondhand Marshall 4x12, and am looking at heads. One thing that i have done in the interim is add an extension socket to my combo (a small 10W practice amp). This works really well and is surprisingly loud and clear. So Im suggesting that this might work even better with your 30w combo, and it would give you a chance to get to know your cab and how much power it really uses. Two things to watch for: Match the impedances of speaker and amp. If the combo works on an 8ohm speaker, you would only be using one channel on that Behringer cab, I believe it is 2 x 8 ohms in stereo. The other thing is to wire the extension socket so that there are no momentary shorts or double connections as youi insert the plug. I used a switched socket. It cuts out the internal speakr before connecting the cab. Doing this is cheap and simple, but get help if you are not confident with such wiring. also, if your combo is new, it could affect warranty. John

Does anyone have a view on whether the larger or smaller ones last longer before they wear out/go scratchy? John

I think it will make no difference at all to your sound, whatever wire you use in the guitar, and whatever gage it is. The subtleties of electron flow in different wire configurations are not sugnifacnt at the tiny currents and moderate frequencies within a guitar. Solid can be easier to strip and shape. Braided is more resistant to breakage if, like me, you want to keep changing the wiring. Even a very thin wire has negligible resistance compared to the pickups. Wires which go outside of the shielded cavity, to a jack socket, or to something like an Les Paul 3-way switch should be screened however. John

Is there another posiibility for the third wire, that it is just a screen, that connects to the pickup body/rear plate but not the coils? The screen would be wired to the ground point. I have this on some old single coils from an '80s Hondo. If you get that cheap digital or anallogue meter, youll soon find out if there is any continuity between the three wires. If it were like mine, with all three wires disconnected from the guitar, the screen wire would have no connection to either of the other wires. Short of getting a meter, how about doing this: 1. get the pickup fully disconnected from the guitar if not already 2. connect pairs of wires to a jack lead to an amp, in turn red/black, red/blue, black/blue 3. lightly tap the pole pieces with a screwdriver to hear a thump 4. if you get that thump only with one pair, then they are the coil wires, the other is a screen 5. if you get a thump with all pairs, then it is more likely that one wire (guessing, blue) is a coil tap, being a connection part way along the coil. The pair with the loudest/deepest thump will be the ends of the coil, with the other wire being the tap Any use? If you had a meter, it would be easier though. John

Thats what I mean, use an SS circuit to boost the signal but only in the clean range, and then let the tube amp go from there into overdrive. If theres not enough to get the result from a 9V supply, two batteries could be used to boost using a circuit designed for an 18V supply. I use JfETs for this type of thing, so that if the booster does saturate a bit, the result is not bipolar-nasty. John

How about just a claen solid-state booster before the input, maybe as a seperate box, to drive the preamp to overdrive? John

OPencan - when I wrote my bit about differences I have found, I was talking generally about JFETs, and as used in common source circuits which are on most of the runofgroove designs. But lovekraft is right that in that Grace design, the FET is just a source follower, which is one of the most tolerant ways of using a JFET, so as stated also in the article, any small N-channel JFET should work there. J

Ive also had trouble finding J201's For a lot of effects designs, the J201 seems to be preffered. The difference appears to be that it has a low gate-source bias voltage Vgs, compared to other types. When used in a common source arrangement, such as in most of the designs on www.runoffgroove.com for example, this results in a higher gain. The best options I have tried are 2N5457 and 2N5484, but these are not equivalent to J201, and the circuits end up with less gain. But I have still had very good results designing circuits for them. 2n3819 and MPF102 seem to have yet higher Vgs, and so offer even less gain in these applications, although they work fine where gain is not too critical, such as in buffer circuits or wher circuits are designed for them. It occurs to me, although i have not tried it, that better results may be obtained with these other JFEts, by adapting deisgns to work at a higher voltage, say 18V instead of 9V. Vgs will then be a smaller proportion of thesupply voltage, allowing a higher drain resistor to be used and improving gain. The above are just my suspicions having played with some of these recently. others please correct if you know better! J

Try wiring 'em directly across the jack temporarily, no switch, no pot, no nothin'! I agree that this "mod' is pretty underwhelming, but it does do something if you wire it correctly. Here is a sound clip that I did a while back, with one schottky wired as lovekraft suggests, using a fairly hot SC pup. It starts clean, then starts again with the diode. It is interesting to hear the decay on the last chord, which gets diode effect all the way down, not just when it is at max volume. http://people.smartchat.net.au/~l_jhewitt/...chottkytest.mp3 Its not a killer sound, but it works. John

At the other end of the Marshall scale - my little MG10 practice amp has a red and a green LED inside to run the overdrive. It is not a bad effect if you like extreme metal in a very small box. Looking through the cracks around the knobs, they light up like a christmas tree when a medium power chord is played. LEDs clip on similar principles to other diodes, but at higher voltages (about 1.8V or more, as compared to 0.6V for silicon), so it depends on the circuit as to whether they are good or bad. John

That is a good tip. With those colours, if you used all gfs for two pups, then wiring up as per SD would work. If all the coils are reversed, the sound is the same. In combo with other makes, there is the further factor of which way the magnet is polarised, whch can further reverse things. So I think the thing is to be aware of the possibiilty of phase issues as you wire up, and if you dont get a proper sounding in-phase combo when yu should, think about reversing wires. With an analogue multimeter, I use a 'screwdriver pull off test'. You set the most sensitive dc voltage setting and put the meter leads across the guitar output, (or the pup wires if you are checking before building). Place a screwdriver tip on a pole piece and lift it up sharply. The meter needle will jump either up or down. You have phasing correct when, for a basic in phase combo, all relevant coils cause the meter to jump in the same direction when you do this test. John

My contribution to these threads is to say dont buy a Blackice for $30. Spend $1 on two IN5419 Schotky diodes. Put them back to back across the output, testing them outside of the guitar. Also try it with just one. It does work, but it is a dry kind of sound and the appeal soon wears off. The best application is to replace a cap on the tone control, and set the tone to not quite max , so there is some resistanace in series with the diodes. This adds a little grit to the clean sound without squashing it too much. It is well worth $1 to try it, but not too much more. John

Heres an idea. If it was a log taper pot (as usual), but wired with the outer lugs reversed, it would behave like that. In that case, volume would be increasing with an anticlockwise turn instead of a normal clockwise. John