and yet another amp build

ezietsman · 2012-12-13T16:52:09+00:00

I started building this amp yesterday. Took me forever to find all my tools. I'm working fairly slowly and carefully, I'd like this one to fire up first time too. Some pics to make this post interesting: The bottom (this one is going to be in a combo with the control panel facing upwards and the tubes hanging down). From left to right the sockets are 12ax7, 12ax7, EL84, EL84 and EZ81. Controls. That's all it will have, 3 knobs and a standby. Heater wiring is done. I'll have some more pics tomorrow, I'm on holiday so this shouldn't take too long ? I do need a few small components so I may be held up if I can't find those quickly. I'm going to start with the turret board shortly.

Blues-Brother

ez wrote Turretboard fitted inside chassis.

I need to attach the output jacks now, install the VVR's mosfet, wire the tone controls, wire the output transformer and put all the wires that connects the turretboard on the valve sockets. Laziness overcame me now so I'll do that later.

Man that looks netjies 8)

ezietsman

Wired in the grounds on the turret board (thin green and thick yellow)

Wired the Volume and Tone controls

Attila

EZ -Miester

looking good there ...

just a comment aren't those red + wire a bit light for the job ... should they not be round about AWG20 (.81mm) or 21 (.72.mm)..... just saying boss

ezietsman

Attila Barath wrote EZ -Miester

looking good there ...

just a comment aren't those red + wire a bit light for the job ... should they not be round about AWG20 (.81mm) or 21 (.72.mm)..... just saying boss

Those thin ones are solid core wire with very thin insulation, they're the same thickness as the component legs, should be fine. I used 18AWG for the heaters, where the current is high and I will use the same for the output transformer's leads. For the rest of the amp the current is really low (milliamps) so this stuff is more than fine.

Attila

yip that will do the trick .... more that fine as you say

ezietsman

Now only the input jack and VVR remains to be wired.

AlanRatcliffe

Looking good!

ez wrote Now only the input jack and VVR remains to be wired.

My only question is how do you stop at that point? ? I'd be in a rush to finish...

ezietsman

Alan Ratcliffe wrote Looking good!

ez wrote Now only the input jack and VVR remains to be wired.
My only question is how do you stop at that point? ? I'd be in a rush to finish...

When it is 1am and your eyes are struggling to focus from being tired/low light/solder fumes you stop ?

I need go over the circuit again carefully before letting the electrons in. Then, I'm hoping the stupid location of the output jacks won't cause hum or oscillation troubles. Fingers crossed.

Edit: Besides, this is not my amp and the owner is on holiday and there is no cabinet for it yet, hence no rush.

Attila

I like it - KISS format VVR, Tone and Volume

By the way with the VVR, what are 4, 6, 8 and 10 in terms of B+ voltages +

ezietsman

Attila Barath wrote I like it - KISS format VVR, Tone and Volume

By the way with the VVR, what are 4, 6, 8 and 10 in terms of B+ voltages +

No idea about the B+ voltages. on 10 it is around 300, on minimum it is a lot less, about 30 or so (amp sounds crap there).

This amp is now done, but something is wrong, it makes sound (not good sound yet) but I have some weird phase inverter voltages, there's prob a cold solder joint somewhere, I'll investigate this further today. Also, I have yet again wired the VVR to be loudest on minimum and quietest on 10. So I'll be fixing those two problems, hopefully they'll come right soon so I can start to build my Tweed Deluxe ?

Sean

Update? ?

ezietsman

The amp is done but there was an issue with the volume cutting out at more-than-half voltages on the PI and Power section, I think I have figured it out, just for fixing now (I hope). Will post an update when I get round to it, which is hopefully tonight.

ezietsman

Found the problem. I used a cap rated for 25V but it got about 50V, it didn't like that. Replaced it with a higher value cap and voila!

The cabinet must still get built so I guess I'll test the amp a bit longer here to make sure it behaves like it should (no funny solder joints and such).

Phew...

ezietsman

Here's some progress pics, of the cabinet, courtesy of lapdawg.

singemonkey

Lapdawg clearly knows his sh** ???

rikus

wow, that's super neat! These are going to look hot when they're done!!!

aja

singemonkey wrote Lapdawg clearly knows his sh** ???

I'm not quite sure how you come to that conclusion. There is nothing in the photographs that would indicate a profound knowledge of manure.

However, he clearly knows his carpentry!

bottledtone

Just gorgeous.....
Love it.
The concept of "oh its gonna be covered by tolex so why bother" is just wrong.
This is how it should be. Made with pride and passion.

ezietsman

The cabinet has been completed. I have few words. There will be a NAD thread soon, with more glamour shots, I'm guessing. ?

lapdawg is clearly a master cabinet builder.

:goodtimes:

shaunf

Breathtaking!

Well done on an outstanding build and well done to Lapdawg on that beautiful cab.

I am thoroughly impressed! ?

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