Twenty-watt, simplified, customized 6g3 build "SBS"
Moderators: pompeiisneaks, Colossal
Twenty-watt, simplified, customized 6g3 build "SBS"
Building this for a client, a simplified version of a 6g3 Brownface Deluxe with SS rectification, adjustable fixed bias, adjustable NFB, and stiffer filtering.
This is all guesswork, and the layout is all new, so all comments on my third draft are welcome and then some.
This is all guesswork, and the layout is all new, so all comments on my third draft are welcome and then some.
You do not have the required permissions to view the files attached to this post.
I build and repair tube amps. http://amps.monkeymatic.com
Re: Twenty-watt, simplified, customized 6g3 build "SBS"
I may be screwing myself by using a single multisection cap for the entire filtering. No way to separate the grounds. What do you think?
I build and repair tube amps. http://amps.monkeymatic.com
Re: Twenty-watt, simplified, customized 6g3 build "SBS"
Watch the cap polarity, the 2 cathode bypasses are reversed.xtian wrote:I may be screwing myself by using a single multisection cap for the entire filtering. No way to separate the grounds. What do you think?
I like to have a safety resistor (50-100K) between the bias pot wiper and the supply end terminal.
rd
Re: Twenty-watt, simplified, customized 6g3 build "SBS"
Thanks. Caps reversed.rdjones wrote:Watch the cap polarity, the 2 cathode bypasses are reversed.xtian wrote:I may be screwing myself by using a single multisection cap for the entire filtering. No way to separate the grounds. What do you think?
I like to have a safety resistor (50-100K) between the bias pot wiper and the supply end terminal.
rd
So, if the bias pot wiper lifts, you've suggesting a voltage from a resistor that connects the wiper to the neg end of the capacitor?
I build and repair tube amps. http://amps.monkeymatic.com
- martin manning
- Posts: 13404
- Joined: Sun Jul 06, 2008 12:43 am
- Location: 39°06' N 84°30' W
Re: Twenty-watt, simplified, customized 6g3 build "SBS"
Yes, that way it fails "cold" so to speak, where the bias voltage goes to max negative instead of floating.
Re: Twenty-watt, simplified, customized 6g3 build "SBS"
Board be built.
I got a sheet of black, 3mm G10 from mcmaster. Decided to buff out the top surface, leaving a really sexy, primer-black, like a radar-invisible race car.
Then I made it extra sexy by glooping gold paint on the board while trying to mark the jumper keys. Duh.
Have just pinned down the components with solder to hold them in place, and will fill and crown after all wiring is in place. Have discovered that the solder in the holes of these large bore turrets will liquify and sink when attaching wires.
I got a sheet of black, 3mm G10 from mcmaster. Decided to buff out the top surface, leaving a really sexy, primer-black, like a radar-invisible race car.
Then I made it extra sexy by glooping gold paint on the board while trying to mark the jumper keys. Duh.
Have just pinned down the components with solder to hold them in place, and will fill and crown after all wiring is in place. Have discovered that the solder in the holes of these large bore turrets will liquify and sink when attaching wires.
You do not have the required permissions to view the files attached to this post.
I build and repair tube amps. http://amps.monkeymatic.com
Re: Twenty-watt, simplified, customized 6g3 build "SBS"
I started doing this when I found a pot that had failed where the resistive element separated from the terminal at the supply end.xtian wrote:Thanks. Caps reversed.rdjones wrote:Watch the cap polarity, the 2 cathode bypasses are reversed.xtian wrote:I may be screwing myself by using a single multisection cap for the entire filtering. No way to separate the grounds. What do you think?
I like to have a safety resistor (50-100K) between the bias pot wiper and the supply end terminal.
rd
So, if the bias pot wiper lifts, you've suggesting a voltage from a resistor that connects the wiper to the neg end of the capacitor?
The wiper still had solid contact with element strip and therefore good continuity to ground.
The high(ish) resistor between center wiper terminal and the supply-end terminal protects against pretty much any form of pot failure.
As Martin says it fails "cold" but usually can still be played through a gig at reduced output or tone.
rd
Re: Twenty-watt, simplified, customized 6g3 build "SBS"
Dimensional drawing p0rn.
You do not have the required permissions to view the files attached to this post.
I build and repair tube amps. http://amps.monkeymatic.com
Re: Twenty-watt, simplified, customized 6g3 build "SBS"
The DR trannies were mentioned in the previous thread - are you sticking with those?
Following this with some interest. Keen to see your further progress.
Following this with some interest. Keen to see your further progress.
__________________________________________
Cheers and Beers.
Cheers and Beers.
Re: Twenty-watt, simplified, customized 6g3 build "SBS"
I'm using Fender and Hammond trannies and choke from CEDist:
http://www.cedist.com/products/P-CF22707
http://www.cedist.com/products/P-TF41316
http://www.cedist.com/products/P-T1760H
Chassis drilled! Time: about three hours, including printing guide (remember to mirror for outside of chassis!), taping, double-checking components, drilling, cutting, filing, and cleaning up (best three dollars spent: deburring tool!).
Three hours means I'd never choose to do this for a client wanting a standard build, man, I'd buy a $90, pre-drilled chassis. I'd only do this much work (and this doesn't include the hours of planning this week!!) for a custom build or for myself.
Amount of blood loss: surprisingly little!
http://www.cedist.com/products/P-CF22707
http://www.cedist.com/products/P-TF41316
http://www.cedist.com/products/P-T1760H
Chassis drilled! Time: about three hours, including printing guide (remember to mirror for outside of chassis!), taping, double-checking components, drilling, cutting, filing, and cleaning up (best three dollars spent: deburring tool!).
Three hours means I'd never choose to do this for a client wanting a standard build, man, I'd buy a $90, pre-drilled chassis. I'd only do this much work (and this doesn't include the hours of planning this week!!) for a custom build or for myself.
Amount of blood loss: surprisingly little!
You do not have the required permissions to view the files attached to this post.
I build and repair tube amps. http://amps.monkeymatic.com
Re: Twenty-watt, simplified, customized 6g3 build "SBS"
Just an observation: don't be a bum. Take an extra moment and drill the index holes for the pots, instead of breaking off those tabs. My last build, the Fiddy BKB, which I put on consignment; I broke the pins off those pots. And what happened? The meat heads --um, "customers"-- turned the knobs so hard, the pots rotated in the chassis until some leads grounded to the chassis. Duh.
I build and repair tube amps. http://amps.monkeymatic.com
Re: Twenty-watt, simplified, customized 6g3 build "SBS"
Next observation: Don't put the components so damn close to the edges of the chassis! Makes it tough to tighten the nuts, man.
Also, someone let me know where I can get test points with a lower profile. People are going to be asking me what those are for…
Also, someone let me know where I can get test points with a lower profile. People are going to be asking me what those are for…
You do not have the required permissions to view the files attached to this post.
I build and repair tube amps. http://amps.monkeymatic.com
Re: Twenty-watt, simplified, customized 6g3 build "SBS"
Hoffman amps has the nice short test points.
Re: Twenty-watt, simplified, customized 6g3 build "SBS"
Looks awesome!
- Reeltarded
- Posts: 9964
- Joined: Sat Feb 14, 2009 4:38 am
- Location: GA USA
Re: Twenty-watt, simplified, customized 6g3 build "SBS"
Great work! Your amps always look great!
I love that bias trimmer tip. Very cool.
I love that bias trimmer tip. Very cool.