Building tube guitar amplifier

[Phil Smith]

So my second huge hobby along with the rocketry and space is music, guitar. So I play it long time and always search for "the best" sound. And one day I decided to build guitar power amp myself. after half-year work I've finished it and it works. Perfectly.
Now I've been building my second amp. The replica of Mesa/boogie mark IIc+ (you know it by metallica's master of puppets album). This is 90watt all tube guitar amp. I decided to exclude reverb and replace presence knob from back to front panel.
All pcb's are completed.

Preamp board:




Power amp board:




Power supply board:


EQ board #1:


EQ board #2:




Chassis (21-gauge (0.8 mm) stainless steel):


Chassis (upside down), Power trans, choke, output trans:


All 8 tubes (4x 12ax7 and 4x6L6):


I hope I'll drill several mounting holes and start assembling and wiring this monster this week. :lol:

 

[Notebook]

Looks very good, how many times have you had a belt off the HT?

N.

 

[Phil Smith]

Looks very good, how many times have you had a belt off the HT?

N.

Sorry but what do you mean by HT?

 

[Notebook]

High Tension! Anode volts on your valves(tubes).
Got a few "encounters" when I was doing bench repairs on CRT tellies, luckily that didn't last long, or neither would I.

N.

 

[Phil Smith]

High Tension! Anode volts on your valves(tubes).
Got a few "encounters" when I was doing bench repairs on CRT tellies, luckily that didn't last long, or neither would I.

N.

Oh yeah, 6L6 plate voltage is 450-460 VDC. but i got not bad experience dealing with that.
btw I got shocked several times (one time with 165 VAC form power trans of ma first amp) - it's not pretty funny i might admit.
so what more can i say?
SAFETY FIRST!

 

[Notebook]

Yes, if in doubt, get someone else to test it, cruel but it works.
Unpleasant experience getting shocked, can't say I ever got used to it, but it did teach me to be carefull around mains volts.

Is that a kit of parts, or is everything homebuilt?

N.

 

[Phil Smith]

Yes, if in doubt, get someone else to test it, cruel but it works.
Unpleasant experience getting shocked, can't say I ever got used to it, but it did teach me to be carefull around mains volts.

Is that a kit of parts, or is everything homebuilt?

N.

sad but true!
actually everything's home-built except chassis and output transformer. I've made the part list and ordered all details in i-net stores.
Boards are great job of my friend. They made by heat toner transfer method.

 

[Notebook]

I haven't made anything for years, did try my hand at etched circuit boards, chemicals had a nasty smell though, went back to Veroboard for most stuff. Those PCBs look excellent.

Good to see people building things, thought it had died out. Maplin is a big supplier in the UK, and I often see projects in Elector magazine I should have a go at:
http://www.elektor.com/

Last project I built was an ETI(Aussie electronics mag, now defunct) 4600 synthesiser, when I thought I was Brian Eno...haven't switched it on for twenty years, guess the electrolytics have dried out by now.

http://www.eti4600synthesiser.org.uk/

N.

 

[Phil Smith]

I haven't made anything for years, did try my hand at etched circuit boards, chemicals had a nasty smell though, went back to Veroboard for most stuff. Those PCBs look excellent.

Good to see people building things, thought it had died out. Maplin is a big supplier in the UK, and I often see projects in Elector magazine I should have a go at:
http://www.elektor.com/

Last project I built was an ETI(Aussie electronics mag, now defunct) 4600 synthesiser, when I thought I was Brian Eno...haven't switched it on for twenty years, guess the electrolytics have dried out by now.

http://www.eti4600synthesiser.org.uk/

N.

Thanks!
Oh this synthy is awesome! looks like a rock! Good job!
I really like "old school" stuff looking like that.
I hope your beauty's not dead or anyway el.caps you can easily replace

 

[Notebook]

Yes, it was good fun building it, taught me a lot, the PCBs were supplied, so that made life easier.
Its sitting on its end in a bedroom, I'll take some photo's and post them , might encourage me to get it going again.

Like to see more of your progress, keep em coming!

N.

 

[Phil Smith]

Yes, it was good fun building it, taught me a lot, the PCBs were supplied, so that made life easier.
Its sitting on its end in a bedroom, I'll take some photo's and post them , might encourage me to get it going again.

Like to see more of your progress, keep em coming!

N.

Thanks a lot!
Check out photos of your one with great pleasure!
next pics of my progress will be shot next evening. I hope.

 

[Phil Smith]

so it's been long time since my last post here, but train keeps rollin' my friends!
I've done power amp and EQ sections so far and almost complete preamp. got a few bugs, but today this baby played for the first time and did it loud & well!
So here are some pics:
Amp itself with knobs installed:


And one gut-shot (preamp pcb is not installed here):



yep, this is a mess, but amp in testing process now and almost everyday I remove/install pcbs over and over again (solder here, solder there...)
So this is my progress

 

[streb2001]

Good to see people building things, thought it had died out.

I have been designing and building electronic accordions for years. At first I etched and drilled my own boards but that was far too much pain so I stumped up and got them made in bulk by a board house ("PCB Train"). I still hand solder the boards though, lead-free solder too.

Some photos:

The finished product



PCBs for one instrument



Main board with CPU and MIDI synthesiser



AUX sockets PCB

 

[ex-orbinaut]

...Now I've been building my second amp. The replica of Mesa/boogie mark IIc+ (you know it by metallica's master of puppets album). This is 90watt all tube guitar amp. I decided to exclude reverb and replace presence knob from back to front panel.
All pcb's are completed. :lol:

:thumbup: Brilliant work!

Need one of these now, for a new metal string electric/acoustic.

Are you willing to share the schematics of the PCB's? You have made them from scratch yourself?

 

[Phil Smith]

2 streb2001 - oh seems to be intersting! like the design! Have any sound samples?

2 Keith - thanks man!
Sure I can share with schematics and PCB but only those I checked for preventing copying my errors. Power amp and EQ are 100% working by now, preamp - in a process.
I'll post them later.

 

[Notebook]

Lovely stuff, any chance of some circuits or schematics?

N.

 

[Phil Smith]

Thanks alot!
yes, I'll post them little bit later

---------- Post added 06-13-13 at 09:50 AM ---------- Previous post was 06-12-13 at 07:06 PM ----------

So here we go.
I. Shematics
a) preamp:
it's still the same pre that original mark IIc+ has. I've just removed reverb circuit:




b) EQ (taken from MARK IV):


transistors are repleced with:
Q1 - MPSA63 - ВС516.
Q2, Q3 - MPSA70 - ВС556.
Q4 - MPSA20-5 - ВС547.

c) Power amp is fusion og mark IIc+ and mark IV power section.
I've drawn my own shematic for it:


d) Power supply unit (PSU).


e) Switching matrix.. I've been workin with this one, so I'll upload it later.

II. PCB's.
I draw all my pcb's in Sprint Layout software.
Here I'll post pics of them (working and checked board only):

1) power amp PCB (100x70 mm) (EDIT - the diod at RY4 was installed wrong. Fixed):



2) EQ main board (80x45 mm):


3) Power supply board (160x100 mm):


Preamp and Eq sliders board I'll upload later.
So Have fun!

 

[Notebook]

Just noticed from drawing 1 above, the input is on the right side of the circuit though the text is not reversed.
Wouldn't have normally noticed(well I would have) usually your average valve(tube) has the grid on the left side of the drawing.

This is most peculiar to me, usually see circuits go left to right?

EDIT: ignore red herring about grid, the whole circuit is drawn the wrong way round to me, hopefully it works and sounds good! Like the "terebele switch" at the top mid-right

Another EDIT:
Just noticed across V2 is a send/return with what I would call a "cross-normalling" connection,
you don't see things like that nowadys. hopefully it goes up to 11?

http://www.youtube.com/watch?v=XuzpsO4ErOQ

Nice pics!

N.

 

[Phil Smith]

Just noticed from drawing 1 above, the input is on the right side of the circuit though the text is not reversed.
Wouldn't have normally noticed(well I would have) usually your average valve(tube) has the grid on the left side of the drawing.

This is most peculiar to me, usually see circuits go left to right?

EDIT: ignore red herring about grid, the whole circuit is drawn the wrong way round to me, hopefully it works and sounds good! Like the "terebele switch" at the top mid-right

Nice pics!

N.

left-to-right surly is a usually form, but all ORIGINAL mesa schematics of mark IIc+ and IV we got right-left direction. :lol:
When I redrawn this one, I prefer "left-to-right"

Btw I'll fix the "TERRIBLE TEREBLE" :rofl:

Another EDIT:
Just noticed across V2 is a send/return with what I would call a "cross-normalling" connection,
you don't see things like that nowadys. hopefully it goes up to 11?

this circuit came from early 80's but it still feels good!
Nice vid! Yes I'll crank it up to 11, cause 11's one louder!:lol:

 

[Notebook]

Good stuff, I know nothing of "mesa" are they an original from the 1950's?. The circuits look like they are.

n.