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

[kscwuzhere]

Hey so I currently have a crack with speedball driving my Hd650s. My current output tube is the Chatham/Tung-sol 5998 and the driver tube is the Tungsram e80cc. I read somewhere that there are some possible circuit changes you can make to run these two tubes optimally and I was just wondering what these changes were? Do I need to replace or add any additional resistors? Thank you bottlehead community!

 

[Paul Birkeland]

What voltages do you get at T1 and T5 with the E80CC?

 

[kscwuzhere]

Terminal 1: 130V
Terminal 5: 121V

 

[Paul Birkeland]

Yeah, that's not really so great. 

Try replacing the 237 R1 resistors with 470 Ohm resistors to see if the voltage bumps down between 55 and 85V.

-PB

 

[xcoolhandx]

Yeah, that's not really so great. 

Try replacing the 237 R1 resistors with 470 Ohm resistors to see if the voltage bumps down between 55 and 85V.

-PB

wouldn't this be a permanent change and how would this affect the other tube rolling ?

 

[kscwuzhere]

So I went ahead and ordered a bunch of 470 ohm resistors, hopefully that'll do the trick!

 

[Paul Birkeland]

wouldn't this be a permanent change and how would this affect the other tube rolling ?

Yes, it would be a permanent change.  Yes, it won't be ideal for other tubes.

 

[JamieMcC]

So I went ahead and ordered a bunch of 470 ohm resistors, hopefully that'll do the trick!

Please post some feed back here on how you get on with the resistor swap, I tend to favour the E80cc also and am very tempted to go down the same path.

Cheers

 

[xcoolhandx]

wouldn't this be a permanent change and how would this affect the other tube rolling ?

Yes, it would be a permanent change.  Yes, it won't be ideal for other tubes.

what could happen if I won't change resistors....would I need one of this attached to Crack 

 

[Paul Birkeland]

what could happen if I won't change resistors....would I need one of this attached to Crack

You'll throw off the operation of the 6080.  The results won't be great (IMO) with both the Speedball and the stock kit.

 

[xcoolhandx]

Thanks Caucasian

 

[kscwuzhere]

Please post some feed back here on how you get on with the resistor swap, I tend to favour the E80cc also and am very tempted to go down the same path.

Cheers

I'll make sure to update this thread with the voltage changes after I swap the resistors.

By switching the resistors and running the tubes optimally, what audible differences would result?

edit: Also, I ended up getting the 1/4W 470ohm 1% metal film resistor, would this suffice for the swap?

 

[xcoolhandx]

what voltage should be appropriate ,I have this circled
http://www.mouser.com/ProductDetail/Vishay-Dale/RN55C4700BB14/?qs=sGAEpiMZZMt7FrWooXVB1yjOewkIa0Gq

http://www.mouser.com/ProductDetail/KOA-Speer/MF1-4CCT52R4700F/?qs=sGAEpiMZZMv8QEQcPUP6BXh8cFBVkBnm

http://www.mouser.com/ProductDetail/Vishay-Beyschlag/MBE04140C4700FC100/?qs=sGAEpiMZZMukHu%252bjC5l7YUGjKnXnGlgNvS%252baD1SLCZo%3d

http://www.ebay.com/itm/161148100242?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

 

[kscwuzhere]

So I ordered the wrong resistor? Are 1/4W 470 ohm resistors fine or should I order something else?

 

[Paul Birkeland]

1/4 Watt will work fine, they will just be physically kind of large.

 

[kscwuzhere]

1/4 Watt will work fine, they will just be physically kind of large.

Hopefully they'll fit!

 

[xcoolhandx]

will 1W work well ..I really want to try this new resistors
http://www.mouser.com/ProductDetail/Vishay-Beyschlag/MBE04140C4700FC100/?qs=sGAEpiMZZMukHu%252bjC5l7YUGjKnXnGlgNvS%252baD1SLCZo%3d

 

[Paul Birkeland]

If a 1/4 Watt resistor is a borderline fit, a 1W really won't work well.

Also, there's no reason to use such a large resistor there, 1/10 of a Watt would be sufficient.

 

[xcoolhandx]

Thank you

 

[JamieMcC]

Would anyone knowledgeable (that rules me out) care to comment on what sort of effect running the bhc+sb+e80cc+ts 5998 & this resistor mod have on a Cracks output impedance. I have read the TS-5998 lowers the Cracks output impedance and wondered if the input tube can also effect this?

Thanks

Jamie