Completed 80's funk chassis

[Funkalicousgroove]

Here are pics.

[Funkalicousgroove]

a few more...

[Funkalicousgroove]

and more

[Funkalicousgroove]

and more

[kleinm]

Thanks for sharing these Brandon. That's very gracious of you!

[Funkalicousgroove]

I hope they help you all with your builds, sorry they took so long.

[dbeeman]

Funk

I was going to say "DYN-O_MITE" but you changed your avatar


thanks

[Funkalicousgroove]

Yes, I am Ming the Merciless now!! GRRRRRRRRR

[mdroberts1243]

I hope they help you all with your builds, sorry they took so long.

Hi Brandon,
Thanks for posting these!
I like the trick of running the screen resistors between two sockets... seems to nicely solve a mechanical problem!
It seems that both you and Heisthl put the standby switch AFTER the 1st set of filter caps, but all the schematics, including Heisthl's BM one, have the standby switch right after the diodes... putting it after the 1st set of filter caps seems nicer from the point of view of tight wiring, good layout, etc. but is there any downside to that?
What's an amp with 100k plate / 1.5k cathode on all four triodes sound like?

Thanks,

[Funkalicousgroove]

I hope they help you all with your builds, sorry they took so long.

Hi Brandon,
Thanks for posting these!
I like the trick of running the screen resistors between two sockets... seems to nicely solve a mechanical problem!
It seems that both you and Heisthl put the standby switch AFTER the 1st set of filter caps, but all the schematics, including Heisthl's BM one, have the standby switch right after the diodes... putting it after the 1st set of filter caps seems nicer from the point of view of tight wiring, good layout, etc. but is there any downside to that?
What's an amp with 100k plate / 1.5k cathode on all four triodes sound like?

Thanks,

The Schematics are incorrect regarding the standby, if that were the case then when you flipped on the switch you'd have like 500v on your plates and caps until they charged.

The 100K/1K5 sounds like HEAVEN, IMHO the way to go on a non HRM build.

[jelle]

I guess it sounds like sn#124...LOL! These 100k's sound really cool I agree. Just try it sometimes.

Funk, that is one great build and thanks for the pics. Same remark on the screenresistors...cool! Couldn't figure that out...thanks.


Jelle

[mdroberts1243]

The Schematics are incorrect regarding the standby, if that were the case then when you flipped on the switch you'd have like 500v on your plates and caps until they charged.

The 100K/1K5 sounds like HEAVEN, IMHO the way to go on a non HRM build.

I like the idea of having the standby switch located post-1st-filter-caps. I don't agree that you will see 500V on the plates... the uncharged caps will look like a dead short and ramp up in voltage based on the source impedance of the transformer, etc... The only drawback I've found in googling around is the additional voltage stress put on the 1st stage filter caps, with no load, there will be a lot more volts on those caps in standby. But this isn't an issue for the Dumble precision supply with the series connected caps, so I'm going to go for it... it cleans up the wiring so nicely!

Looks like trying various combinations of Rp/Rk is going to be a big part of tweaking the BM build.

Thanks,

[Funkalicousgroove]

The Schematics are incorrect regarding the standby, if that were the case then when you flipped on the switch you'd have like 500v on your plates and caps until they charged.

The 100K/1K5 sounds like HEAVEN, IMHO the way to go on a non HRM build.

I like the idea of having the standby switch located post-1st-filter-caps. I don't agree that you will see 500V on the plates... the uncharged caps will look like a dead short and ramp up in voltage based on the source impedance of the transformer, etc... The only drawback I've found in googling around is the additional voltage stress put on the 1st stage filter caps, with no load, there will be a lot more volts on those caps in standby. But this isn't an issue for the Dumble precision supply with the series connected caps, so I'm going to go for it... it cleans up the wiring so nicely!

Looks like trying various combinations of Rp/Rk is going to be a big part of tweaking the BM build.

Thanks,

Disagree if you like, but I speak from experience. This is the way the real ones are wired.



BTW, #124 isn't really unique, there are MANY amps with the 100K/1K5 plate/cathodes. What was most unique about #124 is the 350K trimmer/120K OD entrance network, the way the PAB was wired, and the 300UF caps at the first filtering stage(plates).

[jelle]

The 220k//250pf on the signall access loop...not unique?

[glasman]

When you initially apply power, the caps will draw the supply to 0 volts. After 5 RC time constants (Cfat * resistance of transformer windings) the supply will be at max voltage.

The screen side of the choke is a whole different matter where the LC creates a nice spring and you will have a damped sign wave with a peak amplitude of about 1.4 X nominal voltage. This is why it is a good idea to use a cap with about 1.5X voltage rating for the screen.

For me, I will keep my standby before the CFATS.

Gary