Mikey R

Cheers for the suggestions gents. Yep, hot air gun is the orthodox way to shrink your tubes (!) but I didnt have one handy, I dont think the hair dryer would be hot enough. But I didnt think of using a soldering iron - good suggestion bartelby! So ignoring the heat shrink for the moment (which might not even be necessary) I had a play with how the wiring would look on the actual bases: This single strand wire holds its shape niecely, I dont think the PTFE stuff will be quite so well behaved.

This project is really an exercise in totally overbuilding everything. The heater wiring for the power valves will carry just shy of 10A, so everything needs to be able to handle that. This is a trial run of the heater wiring. (The single strand wire will be replaced in the final implementation with PTFE coated multi strand.) Ive tried using some super chunky heat shrink to keep the wires together, however whilst shirnking it down, I melted both the wire and the cigarette lighter. Rethink needed!

[quote name='Dad3353' timestamp='1366273020' post='2050278'] Nice thought, but a bit late now, anyway, if it's not the case..! [/quote] Dont worry, the power transformer is specced so that I can use 6550s or KT88s, I could probably also use KT90s or KT120s. Unfortunately, with six power valves, tube rolling will be rather expensive! Next question, probably for Mr. Foxen and umph - Im thinking of staking my own turret boards. Ive got some phenolic board on order, does anyone know a cheap place to get turrets from? Ampmaker does screwmount ones: http://www.ampmaker.com/store/Screwmount-turrets.html Bluebell is probably the cheapest for classic turrets, when bought in bulk: http://www.bluebellaudio.com/connectorsturret.htm Any others?

Cheers dude! KT120s are a little weird, theres no typical operation on the data sheets so you have to work it out yourself from the graphs. I believe the new big Matamps are driven by KT120s so you definately can get a great tone from them. Personally, I decided to go with the tried and tested 6550 configuration from the data sheet, I just found it easier. Whatever you go for, good luck!

OP updated with the specs

The big caps and valve bases have arrived, so Ive been figuring out the best layout. Any opinions here would be greatfully received, its a bit of a squeeze. Unusual. This one maximises the space between the power valves and the big caps, whilst keeping the power supply components to one end. Plenty of space for the tag boards also: Classic. This ones a bit like a Hiwatt, with the caps in a line. Im not so keen on this one, as the caps are rather close to the power valves without leaving much space for a heat shield. Also, the wiring for the power supply will need to go right accross the width of the chasis, which will be both untidy and possibly a cause for hum: Or probably my favourite. This one should leave just enough space for the tagboards, but not much space if I want to add anything later. Theres plenty of space for a short heat shield. Also, the power supply is fairly well kept in one place, but the 600V HT supply will be right next to the center tap of the output transformer, which is really handy, and the first valve of the pre-amp is as far from the mains transformer as possible: There are compromises in all of the possible layouts, but thats always the case.

Im going to be running 6 x 6550 at 600v on the plates and 300v on the screens, theres no way I could drop 300 volts at those currents accross a resistor so Ive gone for the (fairly usual) stacked 2 x 300v HT supply.

Theres going to be two HT supplies, stacked one on top of the other, so theres one choke for each. Youre right about the big ones - output on the left and power on the right. This is the provisional layout, I'll know for sure if everything else is going to fit when the caps and valve bases arrive.

The iron has arrived!

How does a 2x10 compare with a 4x10 on axis? Is it just more sensitivity and power handling?

That body is amazing! I would be worried that a figured maple board may be too much bling, just my opinion though and happy to be proven wrong!

Can we get a gut shot? These are 2 x EL34, right?

Wow! Just, wow! Awesome work - looks incredible!

I might get shot for suggesting this - but has anyone been able to A/B the new GT200 against a modern Orange AD200? Similar beasts or totally diverged?

Personally, I think it would be a real shame if Matamp went entirely down the hybrid route and we lost the GT200 from the catalogue. There really is something special about output valves.

Friday night, and Im spending it on the sofa designing the bias circuit... Im leaning towards a Hiwatt style power amp, but modified with the inidividual bias adjust for each power valve from Merlin Blencowes book. Schematics of all the Hiwatt variants are at http://hiwatt.org/tech2.html - this is a really great resource.

Still waiting on the transformers, Johns custom winding them.

What kind of sound are you after?

Billy, was that your Matamp rig at the Harrogate bash a couple of years back? Playing through that rig has had a lasting impact!

[quote name='Sibob' timestamp='1357259883' post='1920166'] Re-jiggled my 'utility' board a bit Si [/quote] Cool, you got a Sonic Kitchen! How you like it?

Thats an odd website, the banner stays in the middle of my screen so youve got to keep scrolling up and down to see the pics around it!

Hi 6v6, Im in a similar boat but approaching it from the other end - got the speaker cab and building the head to match. One thing Ive learnt by reading into this stuff - reproducing bass is way trickier than guitar. A guitar may sound alright through a bass amp but a bass sounds pants through a guitar amp. That extra octave is really hard work and requires the engineering to be so much more precise. Enjoy yourself!

Reverb in the right context can fill alot of space. In the wrong context is also fills alot of space, unfortunately its the space that everyone else is trying to fit into as well. The real problem is sealed 4x12 cabs. A 30 watt open backed combo sits really nicely with a rock drummer and bassist, and doesnt make anyones life difficult, but then I just like that retro sound.

[quote name='thebassman' timestamp='1359983620' post='1962847'] Perhaps i should just nobble the rhythum guitards amp. [/quote] Sounds like a plan! It might be that the rhythm guitarist is stomping on your frequency range, not the other way around. Try cutting some of the low frequencies on the guitar amp.

[quote name='3below' timestamp='1359762395' post='1960182'] Excellent, share the specs please. [/quote] Youre just going to have to wait