new build: 50w Bluesmaster HRM combo

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norburybrook
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new build: 50w Bluesmaster HRM combo

Post by norburybrook »

well it had to happen:

I had the cabinet left from the peavey Deuce which was the donor amp for my Wonderland build.

I had an old chassis lying around to so thought I'd see if I could get them to match up. I had to cut 10mm of the end of the chassis so it would fit in the cabinet which meant loosing the mounting nuts, but I've put cage nut's in the open end so should be no problem. Cut the combo cab front like the Dumble cabs and added a crossbar. I need to make a large oval cut back panel now.

I'm mounting the OT at the end of the chassis so hopefully there'll be enough room for the speaker. Transformers arrived to day from InMadOut in Italy wound to spec, they've been great in all my builds and no need for an extra transformer for the relays as I get an extra 6v secondary wound.

I've been using old bit's and pieces left over from various builds etc so it will be interesting how this turns out. Check out those diodes on the rectifier board......Jelle mention something about these diodes sounding better than the standard ones!!!!!!!! so I thought I'd give them a try.

It's a small combo , like an old messa boogie MkII but I think it should be a great grab and go machine. Goint to do blonde tolex with black vox grill as I really like that look now I've done my #102 and cab.

watch this space;
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stelligan
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Re: new build: 50w Bluesmaster HRM combo

Post by stelligan »

Yeah, man! Loves me some HRM overdrive. Looks like a great start!
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norburybrook
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Re: new build: 50w Bluesmaster HRM combo

Post by norburybrook »

thanks,

the BM has an incredible clean sound and is nice and loud so 50w should be fine.

The Deuce was originally a 100w combo and weighed about as much as a dying sun!!

I've a feeling this will weigh a similar amount but I'm liking the small for factor.

Hope it sounds as good as my last BM build which is now owned by Eric Clapton's former guitarist!!!


M

P.S. I'm on tour oat the moment so will be doing this around my live dates when I'm home.
dcribbs1412
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Re: new build: 50w Bluesmaster HRM combo

Post by dcribbs1412 »

Nice re-purpose of cab and chassis.
What diodes are you using, GP30M?

D
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norburybrook
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Re: new build: 50w Bluesmaster HRM combo

Post by norburybrook »

dcribbs1412 wrote: Wed Jun 07, 2017 3:40 pm Nice re-purpose of cab and chassis.
What diodes are you using, GP30M?

D
sorry missed this....

yes that's the ones

http://www.mouser.co.uk/Search/ProductD ... 0M-E3%2f73

marcus
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norburybrook
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Re: new build: 50w Bluesmaster HRM combo

Post by norburybrook »

Ok building relay boards today.....1/16th eyelets......fun :D

so looking at the bluesmaster layout it seems the relays are wired differently from my last build.

am I correct in thinking that I can just jumper these connections on top of my relay boards as I'm connecting with wire as it's not a PCB?
Bluesmaster relays.jpg

TIA

marcus
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gz34
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Re: new build: 50w Bluesmaster HRM combo

Post by gz34 »

Marcus, I've made boards that way before, and never thought that they looked that great. I bought some ready made boards and power supply boards from dave at colossal amps, absolute works of art. However, I've recently got some from Taylor, and could send you a couple if you want them, no charge of course. just PM me if you would like them.
Terry.
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norburybrook
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Re: new build: 50w Bluesmaster HRM combo

Post by norburybrook »

terry, that's very kind.

I've just spent half a day making these so I'm going to carry on with what I've got but I'll PM you as I've another build in mind ;D
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marcus
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martin manning
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Re: new build: 50w Bluesmaster HRM combo

Post by martin manning »

norburybrook wrote: Mon Jun 12, 2017 3:22 pm...am I correct in thinking that I can just jumper these connections on top of my relay boards as I'm connecting with wire as it's not a PCB?
No, none of that! The coil circuit is independent from the audio
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norburybrook
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Re: new build: 50w Bluesmaster HRM combo

Post by norburybrook »

yes, I'd a feeling something wasn't quite right connecting the audio side to the coil. I just remembered a previous build where there were pins on the relays connected and the layout looked just like that one.

Anyway, thanks Martin.

been working bit by bit on this and here where I am at the end of todays few hours. Transformers/choke are now in.

I have a bunch of old Mullard EL34's and though I might try a pair in this build, it would be a first. What's the bias calculation for eL34'S compared to 6L6's?

and is it a case of just manually inserting valves and measuring bias voltage to find a pair when I do get to that point?

here's some pics.
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the chassis is very 'Ghetto' as I recued it from the bin.....I'm using various bit's and pieces I have to hand so I'm not too worried about 100% authenticity with this build just using what I have.


M
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martin manning
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Re: new build: 50w Bluesmaster HRM combo

Post by martin manning »

EL34 is 25W Pa max, so you want to bias at about 17.5W. Yes you can try tubes until you find a reasonably matched set. I think I'd put just one in, bias it, mark the cathode current on it, then do the same for all the other candidates using the same socket. Then select the ones you want to use. Don't forget to connect a load.
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norburybrook
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Re: new build: 50w Bluesmaster HRM combo

Post by norburybrook »

and todays progress :D
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still looking like a rats nest but hopefully I can tidy some things up when it's done.


back out on the road tomorrow so there'll be no more updates this week.



Marcus
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norburybrook
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Re: new build: 50w Bluesmaster HRM combo

Post by norburybrook »

home for a couple of days so finished off the wiring last night.
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not my prettiest build it's a real parts bin special. The chassis did come out of the bin, rescued at the eleventh hour, I should probably get some blanking plates for the unused holes.

Everything else is stock values although there's a mishmash of resistor types in various places and the 0.1uf film cap is way over spec, hence it's size.


Going to try with some old Mullard El34's I have lying around purely because I've never used EL34's in any of my builds. and I've got half a dozen sat here in a box.

Be interesting to see if moving the OT to the far side of the chassis has had any sonic effect....good or bad.


OK time to get the trusty light bulb limiter out and check me some voltages......................TBC


M
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norburybrook
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Re: new build: 50w Bluesmaster HRM combo

Post by norburybrook »

right.

All voltages are great across the board, I've about 425 on the plates with these EL34's in.

V1,2 and 3 are all in the ball park across all pins.


BIAS; I've only got a maximum of 13 mv in my bias range with these EL34's , I recon I'll need about 40-43Mv to bias properly can I get than by changing the resistor on the pot, or do I need to change the board resistor? reason is the board resistor will be a real pig to get out now. I've got 1k2 there, and 27k on the pot.


edit...changing to a 15k on the pot was all that was needed.


right so all voltages are good now, however.....there's always a however......I've no sound through the pre amp. if I flick the rear switches to OD and Boost can just get a barely an audible sound. Plugging a guitar into the return on the back of the amp gives me a good clean signal, so the Output section is fine.

this is where an audio probe would be handy, anyone suggest a starting point to trace this issue? I'm sure it's something I've done wrong as all the voltages check out perfectly

cheers

marcus
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martin manning
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Re: new build: 50w Bluesmaster HRM combo

Post by martin manning »

I recommend changing the board resistor to raise the mid point of the bias range. The pot and ground resistor together set the range and current so you should keep them the same.
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