Modifications to run e80cc/12bh7a/5687 for Crack+Speedball

[kscwuzhere]

So I finally got done with the mod, voltages check out and I'm extremely pleased with the results!
I ended up replacing the two R1 resistors (237ohm) on the small speedball boards with 470ohm resistors. I then wanted a way to switch back to the original set up for 12AU7 rolling, so I wired a SPST (single-pole single throw) in series with another 470ohm resistor, which was then wired in parallel with the newly installed 470ohm resistors. When the switch is turned on the resistance through R1 drops to 235ohm and voltages check out!
Thank you bottlehead community!

edit: In terms of sonic differences, I've noticed a more controlled low end combined with an increase in detail in the mids. Current set-up is tungsol 5998 + tungsram e80cc + hd650s.

[JamieMcC]

Neat idea which I might steal it if you don't mind

[kscwuzhere]

Steal away! That's what its all about!

[xcoolhandx]

great mod  kscwuzhere,thanks for sharing

[kscwuzhere]

Absolutely! I got the idea from the ecc32 thread so I'd thank the contributors of that thread 

[xcoolhandx]

Absolutely! I got the idea from the ecc32 thread so I'd thank the contributors of that thread 

6SN7,12AU7 =( T1 75V / T2 76V )-very happy with this 
E80CC=( 85/86V )
12BH7A=(55/57V )

Thank you Sir !!

[kscwuzhere]

Absolutely! I got the idea from the ecc32 thread so I'd thank the contributors of that thread 

6SN7,12AU7 =( T1 75V / T2 76V )-very happy with this 
E80CC=( 85/86V )
12BH7A=(55/57V )

Thank you Sir !!

Nice work! Love the finish on your build.

[JamieMcC]

OK started looking for a pair of switches lots of choices but what voltage rating should I be looking at to keep things safe?

[kscwuzhere]

This: http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_317287_-1 is what i used

[Paul Birkeland]

OK started looking for a pair of switches lots of choices but what voltage rating should I be looking at to keep things safe?

Voltage rating isn't important.  The switch will have less than 2V across it, and technically will never be switched when any DC voltage is present.

I still do recommend gluing them to the PC boards.

-PB

[kscwuzhere]

OK started looking for a pair of switches lots of choices but what voltage rating should I be looking at to keep things safe?

Voltage rating isn't important.  The switch will have less than 2V across it, and technically will never be switched when any DC voltage is present.

I still do recommend gluing them to the PC boards.

-PB

When applying the glue, put some on the pc board and wait ~2mins for the glue to dry a little. Then, place the spst in the appropriate position and hold it for another minute or so. This method will ensure minimal glue overapplication, which prevents the glue to splurge from the sides and will ensure a tight fit.

Gotta thank Paul for this was his advice to me!

[JamieMcC]

Super thanks, will probably will use a dab of hot glue to fix the switch in place, already have the resistors the switches should turn up in a couple of days.

[kscwuzhere]

Super thanks, will probably will use a dab of hot glue to fix the switch in place, already have the resistors the switches should turn up in a couple of days.

Make sure to post some pictures when you get done with it

[Paul Joppa]

Super thanks, will probably will use a dab of hot glue to fix the switch in place, already have the resistors the switches should turn up in a couple of days.

You might possibly want a glue with a higher melting point ...

[JamieMcC]

Super thanks, will probably will use a dab of hot glue to fix the switch in place, already have the resistors the switches should turn up in a couple of days.

You might possibly want a glue with a higher melting point ...

Thanks Paul my glue gun is a industrial high temp one the glue melts at 195°C  so should be fine but will take some readings with the inferred thermometer to check first.