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Until you ship them and pay for customs charges

postage adds a lot to the price on the heavier things

yeah I might have a rethink....with the US kits with shipping etc i'll be lucky to get out under a grand

I've built a semi-working amp and worked on a couple . . . can I recommend that you start simple. Something like a Fender Champ/Vox AC4 type thing. Do the 18 watt as a second build.

yeah that's a fair point .... cheers

eh I built a 50Watt plexi for my first build, still running fine and I only got shocked the once!

You'll be fine. Just heed the warnings and do your research. You will need to know the basics. Things like Cap polarity and the voltages expected at various points in the amp to when it's complete. Be very thorough and as neat and organised as possible. I'd recommend a kit. I've built quite a bit of stuff and only 1 shock while checking voltages with the amp on. Twas terrible though.

fuzziebro wrote:ive only had one shock to date, touch wood, but it was 450vdc from 3x power 100uf caps... i was carrying the chassis and a loose wire from a top-cap valve - an 807 - dropped onto my arm, it was not pleasant, and i had heart palpitations for a week or so afterwards...

you need to dis charge the power caps each and every time before making adjustments/mods... and check with a multimeter that they are actually discharged... normally a couple of alligator clip/leads with a 10k power resistor make a useful discharge tool.. but you'll need to skill up on this stuff via suitable googling etc...

This is why building in a bleeder network on the reservoir cap is a good idea. I do this on every amp, and combine it with a heater elevation supply (see attachment).

Also a good idea to get into the habit of putting an alligator-clamped bleeder resistor across HT and ground when you work on an amp, just in case you come across one without one built in.

Yep, thats my recomendation too...as per previous post... as for building it into the power supply like tubeswell recomends, well I know some mesa/boogie schems have it as standard, but none of the early marshall/fender amps did... my only thoughts on that (and it is pure conjecture cos I havent tried it and listened for any difference in tone/feel) but I do wonder how a permanent bleeder resistor may load the power supply possibly changing how it responds dynamically... be good to test this at some point...

A permanent bleeder won't affect the B+ if it is sized appropriately. 220k-270k is a good size. To take an example, the current 'stolen' from a B+ of (say) 400V with 220k is 400/220,000 = 0.0018A (or 1.8mA), which won't affect the B+ at all.

(To put it in perspective, taking the example of a little old 5E3 PT with a 325-0-325 HT winding and a 5Y3GT rectifier, the B+ will put out about 390-400 unloaded and sink to about 350 with the tubes all plugged in. Each 6V6 draws about 40mA and each 12AX7 draws about 2mA, so that's 84mA in total making the load drop by about 50V. An extra 2mA from a 220k bleeder resistor is adding another 1/40th to this load, so the extra voltage drop on the B+ would amount to about 1.2Volts lower, which is unnoticeable from the point of view of 350V).

tubeswell wrote:A permanent bleeder won't affect the B+ if it is sized appropriately. 220k-270k is a good size. To take an example, the current 'stolen' from a B+ of (say) 400V with 220k is 400/220,000 = 0.0018A (or 1.8mA), which won't affect the B+ at all.

(To put it in perspective, taking the example of a little old 5E3 PT with a 325-0-325 HT winding and a 5Y3GT rectifier, the B+ will put out about 390-400 unloaded and sink to about 350 with the tubes all plugged in. Each 6V6 draws about 40mA and each 12AX7 draws about 2mA, so that's 84mA in total making the load drop by about 50V. An extra 2mA from a 220k bleeder resistor is adding another 1/40th to this load, so the extra voltage drop on the B+ would amount to about 1.2Volts lower, which is unnoticeable from the point of view of 350V).

This is good advise; thanks for reminding me about basic ohms law too... Cant wait to get my stuff unpacked and settle down and do some building again...

tubeswell wrote:A permanent bleeder won't affect the B+ if it is sized appropriately. 220k-270k is a good size. To take an example, the current 'stolen' from a B+ of (say) 400V with 220k is 400/220,000 = 0.0018A (or 1.8mA), which won't affect the B+ at all.

(To put it in perspective, taking the example of a little old 5E3 PT with a 325-0-325 HT winding and a 5Y3GT rectifier, the B+ will put out about 390-400 unloaded and sink to about 350 with the tubes all plugged in. Each 6V6 draws about 40mA and each 12AX7 draws about 2mA, so that's 84mA in total making the load drop by about 50V. An extra 2mA from a 220k bleeder resistor is adding another 1/40th to this load, so the extra voltage drop on the B+ would amount to about 1.2Volts lower, which is unnoticeable from the point of view of 350V).

Nah.. that's it... i'm out!

philly wrote: Nah.. that's it... i'm out!

Did you say you'd built some pedals b4?

good place to start and stay actually; pedal building is a lot of fun!