Maestro - Brass Master : the corrections  [schematic]

Discussion regarding early stompbox technology: 1960-1975 Please keep discussion focused and contribute what info you have...
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mancunian
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Post by mancunian »

DavidRavenMoon wrote:OK, I got it working!

gtrgeek1 is correct... there seems to be nothing wrong with the original schematic (except for Q1's supply voltage being 8V and not 9V), and RG's PCB is correct.

So here's what I did... first there was the issue where on RG's layout sheet R22 and R27 are swapped. So I removed them and put them in the correct locations. That did little to help the Brass switch, but I at least heard something when I switched it. I had tried moving where R29 connected to C13, but I switched that back to the original location.

I decided to check Q6, since that was responsible for amplifying the output of the filter and sending it back to the circuit. I looked up the pin out for the Fairchild 2N5308.. voilà! I had it in backwards. It did match the layout as far as where the flat side was, but it had the emitter and collector swapped!

So I carefully unsoldered it and flipped it around.

Here's the results. First you hear the two settings of the Brass switch, then I flip the Harmonic switch, and then switch the Brass switch again. You go from very full to very thin, just like the real thing. The very thin setting is what Squire used a lot, as in the example I play from Close to the Edge, which has the dry signal mixed back in.

Brassmaster Fixed

I don't have a real one in front of me to compare, but going from memory, this is pretty much nails the tones I remember using.

Yay! :D
Top Man!

Cheers
Nick

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lohstah
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Post by lohstah »

first, i wanna say thanks to everybody that contributed in finally getting this riddle solved. i flipped around the transistor on my build 2 days ago (had the resistors swapped right from the start), and yesterday i tried it out in my rehearsal room with my aguilar. i´m really happy, all the switch positions work now.

malekko made a clone, and he has germanium versions out. from what i can tell from the pictures, he replaces the diodes with germ diodes, and puts one germ trannie (must be npn) in the circuit. people say that the result is a smoother sound, not as harsh as the original.

cheers,
lohstah

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chicago_mike
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Post by chicago_mike »

Now its time to showcase our brassmaster builds.

Im painting my case today so long as I have some time. Sparkle Red, should be pretty cool. :)
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DavidRavenMoon
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Post by DavidRavenMoon »

chicago_mike wrote:Now its time to showcase our brassmaster builds.

Im painting my case today so long as I have some time. Sparkle Red, should be pretty cool. :)
Nothing special about mine... but it has a certain understated charm. ;) ("there's none blacker") I used a predrilled enclosure, which was a mistake. I had to move the jacks down more to make room, and I would have liked to have the foot switch more towards the bottom. I have a drill press, so I don't know what I was thinking. Seemed like a good idea at the time. This is the first pedal I've built in about (cough) 20 years (cough) so.... I was rusty!

I was also impatient to use it, so I didn't let the paint dry long enough.... :oops: Next time I'll get a powder coated case and drill my own holes. I was going to label it, but I'll wait until I build the next one. I know what everything does so...

The knobs, switches and foot switch were all in my parts bin. I've had those knobs about 30 years!

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sonicvi
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Post by sonicvi »

Here's my Brassmaster. I built it a few years ago using RG's layout, but Josh at Malekko was incredibly awesome and modified it for me maybe a year and a half ago. I recently rehoused it in a bubblegum pink box from PPP. I won't horrify you with a pic of the mess of wires inside.
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Post by DavidRavenMoon »

Very nice! I like that layout. That's how I should have done mine (and would have if I hadn't bought a predrilled case!).

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rcubed
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Post by rcubed »

What size enclosures are you guys using? I need to order one.

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sonicvi
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Post by sonicvi »

1590BB, but it's a tight fit. A 1790 will give you more room to work with.

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rcubed
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Post by rcubed »

Well I think I can squeeze it into a 1590B enclosure. If not, all use them for a different project and get a 1590BB. The 1590B is a tad thinner but has a bit more room length and width-wise than the 1590BB.

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Post by sonicvi »

You must be thinking of something else. The 1590B is much smaller than the 1590BB and far too small for this project.

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Post by rcubed »

I bought this one, going by their dimensions: http://www.effectsconnection.com/oscomm ... ucts_id=56

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Post by mancunian »

I used a 1590J for mine, probably a bit on the biggish side, but at least everything fits comfortably.

It's a great pedal isn't it! :D

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Post by lohstah »

here´s mine:
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somehow the clear coat got marred by something dropping on it, those stains cannot be cleaned anymore otherwise everything comes off. maybe i´ll redo the clear coat in the summer.
the maroon-like colour isn´t done justice in the pictures, it´s redder in reality and has a metallic sparkle.

cheers,
lohstah

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Post by mancunian »

Here's mine, a bit boring in comparison to the beautiful examples above. Need to paint it, anybody have any suggestions.
Another big thanks to everyone who sussed out the gremlins for this amazing pedal.

Cheers
Nick

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Post by noelgrassy »

So, do these only work with Bass?

Will the higher register of the guitar even get this circuit "funkin'"?

What are the Ge xistors Malekko uses? Was sourcing the parts for this rather easy or a real bitch?

I'm super stoked to see you folks isolating the contentious nits this puppy was plagued with for so long...

Thanks for sharing the wealth!!!

NG
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sonicvi
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Post by sonicvi »

noelgrassy wrote:So, do these only work with Bass?

Will the higher register of the guitar even get this circuit "funkin'"?

What are the Ge xistors Malekko uses? Was sourcing the parts for this rather easy or a real bitch?

I'm super stoked to see you folks isolating the contentious nits this puppy was plagued with for so long...

Thanks for sharing the wealth!!!

NG

They work fine with guitar too.
Malekko replaces one of the transistors (don't know which one) and the diodes, in the unit I have it's an AC127 and 1N34's.

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Post by DavidRavenMoon »

noelgrassy wrote:So, do these only work with Bass?
You can use them with guitar for a crazy octave up gated type of fuzz.

Here's my clone with guitar... various settings of the switches, and first with the sensitivity down. Near the end I turn up the dry channel and mix some fuzz in.

Brassmaster with guitar

Here is is with the sensitivity almost off, and the volume control on the guitar half way off.

Brassmaster with guitar 2
Will the higher register of the guitar even get this circuit "funkin'"?
It's great on the top register. Forget about playing chords though.
Was sourcing the parts for this rather easy or a real bitch?

I'm super stoked to see you folks isolating the contentious nits this puppy was plagued with for so long...

Thanks for sharing the wealth!!!

NG
The real thing uses silicon transistors. I don't know what Ge he's using. I ordered all the parts from Mouser. It was easy as pie. ;)
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lohstah
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Post by lohstah »

Malekko replaces one of the transistors (don't know which one) and the diodes, in the unit I have it's an AC127 and 1N34's.
could you look up which one of the transistors it is that he replaced ? that would be great.

cheers,
lohstah

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9 volt
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Post by 9 volt »

Could you use a 3k to 3k transformer? (1:1) Thanks

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Post by busterbassballs »

Could you use a 3k to 3k transformer? (1:1) Thanks
Yes, That's what I used on my first one (from Jaycar?) and it works fine!

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