Helpful hint for the day!

[steeve_a]

A pin vise with a selection of small gauge drill bits comes in very handy if you are repairing or rewiring a printed circuit board. I was having a hell of a time replacing the ceramic treble cap with a mica one on a Mesa Maverick since it was wedged between the bass cap and filter caps. I could not get my desolder tool in there and needed the hole open (my desolder braid wasn't removing all of the solder). Pin vise to the rescue! I used one of the smallest bits because I did not want to screw up the trace. (I would not have had all of that trouble if I had the smaller size mica cap.) And my pin vise is indispensable when I am reconfiguring a pcb for a conversion mod for adding parts or jumpers.

They sell little kits with maybe a dozen small gauge bits that fit inside the handle of the pin vise. Those bits are tiny; if you don't have a good place to put them they will disappear. Being able to put them back in the handle when you are done is a good feature.

Steve Ahola

[gingertube]

Hint for Amp builders.
Many of those big switches (power and standby) come from the parts supplier with a plate that has ON - OFF marked on it and engages in a keyway on the switch bush. When bulding a new amp don't throw those plates away. Put them on the inside of the chassis and just before mounting the switch, wipe some 5 minute araldyte on the wings of that plate. It then sticks to the inside of the chassis and because of the keyway becomes an "anti-rotation" device for the switch.

When laying out a new chassis (I use Hammond Chassis) cover the entire outside with low tack masking tape. That allows you to mark all the holes for mounting of switches, pots, tube sockets, transformer mounts etc. It also protects the chassis from dings and scratches during the "metal bashing".

Cheers,
Ian

[gingertube]

From this:

[gingertube]

To this - a London Power Standard with full Power Scaling - 4 x 6V6G

Labelling is a Brother 'P-Touch' machine using a white on clear tape.

[gingertube]

Too plain for you - then spiff up the speakerbox with a bit of snake skin tolex

Cheers,
Ian

[M Fowler]

Ian,

Nice job on your amp. I tried using that clear label making tape but must not have your talent at making it look good.

What is the guitar your playing?

Mark

[Colossal]

Ian,

Nice work! Bet those old 6L6G/GAs sound really sweet! Well done.

[steeve_a]

Amazing! Did you add a coating over the labeling tape?

Steve

[gingertube]

No coating over the labels - the guitar is actually my friend's Guilld (the friend for whom I built this amp).
Outputs were a quad of 6V6G. Quads of 6V6 actually sound stunning - still some of that 6V6 grind but smoother than just a pair.

Here is another pic of the amp during build showing the use of those switch plates as anti-rotation devices.

The switches in this case are Fixed/Cathode Bias switch and the Triode/Pentode Switch for one Output Tube pair with the fixed bias test points and adjustment pots shown. this is duplicated for the second output tube pair.

Another hint. set those bias adjust pots to their full anti-clockwise position when you mount them. That way when you wire it it is very easy (with the multimeter) to tell which end to wire where to achieve minimum idle current (max bias voltage) at this full anticlockwise setting. Then when the amp is done, clockwise adjustment turns up the idle current.

The rotary switch is the 4/8/16 Ohm Speaker Impedance selector. It is a 3 pole, 3 position switch - I wired all three poles in parallel - why? for current rating, speaker current can get very high, this amp is about 32 Watts, that is, nearly 3 Amps into 4 Ohms. I have some more pics of the build. Yell if you want me to post a few more - don't want to hi-jack the thread or bore anyone.

Cheers,
Ian

[steeve_a]

More hints are what I wanted here- especially hints from other people since I don't learn much reading my own hints.

So is your impedance selector switch make-before-break or break-before-make, and does it really make a difference for a tube amp?

I know that a lot of Marshall OT's were trashed because of problems with their impedance selector switches so making them extra-strong is a good idea. I like to have separate jacks for the different impedances but it does take up more real estate on the rear panel.

Thanks!

Steve

[steeve_a]

The Myth of Audio Taper Pots

It is one of those things that we all just assume is true... we are dealing with audio signals so we obviously want an audio (logarithmic) taper on volume controls. Period.

I beg to disagree. If you are turning the volume control up from 0 then an audio taper usually works better for you (rather than getting blasting with too much volume too soon). However if you are turning down the volume control from 10 (as on your guitar) then a linear taper pot gives you much more control over your signal level. In fact I would even go for a reverse audio taper pot myself although some people would consider that to be overkill. The linear (or reverse audio) taper is particularly important if you are playing an amp (or OD pedal) that goes from nice'n'dirty to nice'n'clean as you back off the volume control on your guitar.

There is one notable exception: if you like to do volume swells on your guitar using your pinky, then you do want an audio taper pot (since you are interested in turning your guitar up from 0.)

If you look back to the early days of electronics you did want an audio taper volume control on an amplifier or radio so as to not blast you out of hearth and home. (Those early devices could get extremely noisy and that was with the volume turned way down.)

That is just my own opinion and I believe that everyone has the right to disagree- it's a free country and I will defend their right to be wrong if that is what they so choose.

Steve Ahola

P.S. That last line was a joke. I got unfriended over at FB because I posted something like that on someone's wall and they didn't realize that it was supposed to be a joke. Oh well- win a few, lose a few.

[LeftyStrat]

To this - a London Power Standard with full Power Scaling - 4 x 6V6G

Do you have any clips of this amp? I've never been able to find any clips of any London Power designs.

[Gaz]

Here's a little trick that made my wiring a lot faster with less wasted wire:

Before cutting a wire to length, I like to make a very light mark on the jacket of the wire with some dykes to mark where I need to strip the wire, thencut the wire a little bit above that.

I was sick of cutting a wire and guessing everytime where to strip. I'd usually end up taking off too much and have to trash the wire. This way I don't have to guess or think about where to strip.

[rp]

This isn't a hint, as we all know this, but a reminder to the lazy among you: Put a dud/cheap tube in the socket before soldering. I got lazy and stopped doing it and got nailed on my new 5F1. Lost a $3 Belton, and since the amp is ptp created a real nice PITA for myself. Just do it.

Oh, and before you freak out and decided your soldering station died, make sure you are not trying to solder with buss wire

Don't solder at 3AM.

[steeve_a]

Oh, and before you freak out and decided your soldering station died, make sure you are not trying to solder with buss wire

I'll find myself wondering why the damn solder is getting so hot and burning my fingers! Speaking of buss wire, I was going to mention that I have two rolls of 22 and 24ga that I use with heat shrink tubing for intricate wiring on guitar wiring harnesses, etc. I have had those two rolls for over twenty years.

Speaking of rolls of wire I will cut a narrow angled notch on the flange of the spool to keep the wire from unwinding. I might have to discard the piece where it is kinked but it is better than having the whole roll unwind. Another trick that lasts a few years is to use rubber bands: wrap the rubber band around the end of wire several times and then loop the rubber band around the whole roll. (If you leave the rubber band on for a few years it will probably fall apart, leaving little bits bonded to the insulation, so it is good to replace the rubber band before that happens.)

Don't solder at 3AM.

Or right before a gig when you are planning to use the equipment that you are working on. Rushing to get something finished any time of the day usually screws something up for me... "just 5 more minutes of soldering and I'm done!"

Thanks!

Steve Ahola