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

[Paul Joppa]

OK no sweat, should not go much over 60C. I was thinking the home craft type.

[JamieMcC]

So I replaced my resistors and installed the switches all went well and I am delighted with the results I am hearing. The music feels tighter more coherent with better textures and substance to it.

So a big thank you to those who have paved the way.

 


 

[xcoolhandx]

what reading are you getting when switched ? (12AU7/E80CC) ,looking good Jamie !
 P.S. I used very light "rocker switches " so direct soldier worked great for me ,switches feel sturdy,all I need to do is lift the unit on one side without flipping  to make the adjustment,this mod should be sticky in my opinion 

[JamieMcC]

Switched to run E80cc

T1 80.01
T5 79.98

Switch to run 12au7

T1 74.4
T5 76.7

[xcoolhandx]

better then what I'm getting -20v jump

[JamieMcC]

I wonder why the difference? Perhaps its down to mains voltage 240 here.

[kscwuzhere]

Yeah I'm getting the following readings:

12AU7:
T1 74V
T5 76V

E80CC:
T1:84
T5: 82

Maybe try a difference switch?

[xcoolhandx]

Yeah I'm getting the following readings:

12AU7:
T1 74V
T5 76V

E80CC:
T1:84
T5: 82

Maybe try a difference switch?

that's pretty close to what I'm getting
6SN7,12AU7 =( T1 75V / T2 76V )* [88V before]-very happy with this 
E80CC=( 85/86V )*[105V before]
12BH7A=(55/57V )*[SAME Before]

I'm not sure if this have anything to do with the switch but as long as I'm in the "55~88v " window there is  nothing to complain about 

[kscwuzhere]

Those readings are perfect! How have you been enjoying the mod?

[xcoolhandx]

I love this mod ,wish 12BH7A voltage was little higher ,since this tubes sound awesome..

[onelivewire]

I just installed this mod today, with two 470ohm resistors running in parallel for normal function and a single 470ohm for the e80cc. I also tried the 12bh7 with my t1s running on each circuit, and found that I preferred it to my current Mullard ecc82. So, I've decided that I want 3 different resistance settings, one stock (270ohm), one @470 for e80cc's, and one @200 for 12bh7's.

Would throwing the stock R1 resistor back in and adding a 634ohm resistor on one throw of a SPDT to net 470ohms (e80cc), and a 768ohm resistor on the second throw to net 200ohms (12bh7) let me accomplish this? I figure that the off position will give me the stock resistance with a On-Off-On SPDT: http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_72557_-1

Edit: Or it seems I could just add another 348ohm (I think?) resistor as the second "on" position parallel to the 470ohm I've already installed in order to achieve the 200ohm resistance for the 12bh7?

[serpent68]

This mod is really brilliant, I've decided to go for it and hope I don't break anything in the process

Does the 470 ohm take the E80CC with any power tubes or just the 5998?  If I decide to use the E80CC with a 6080, do I toggle the switch to the 237ohm or 470ohm?  I love the E80CC + Bendix 6080WB combo for faster music.

[kscwuzhere]

I believe this mod will work with the 6080wb under the 470ohm resistance position. How would you compare the sound of the e80cc+5998 vs e80cc+6080wb? Which cans are you using?

[serpent68]

I believe this mod will work with the 6080wb under the 470ohm resistance position. How would you compare the sound of the e80cc+5998 vs e80cc+6080wb? Which cans are you using?

With the E80CC, the 5998 has superior details, transparency and soundstage size.  The 6080WB betters the 5998 in terms of dynamics, drive, and bass punch. 

For jazz, vocals, and most slow music, I strongly prefer the 5998 + E80CC. With electronic and rock music, the 6080WB has the added drive and weight that makes it more enjoyable.

I'm intrigue by the 470 ohm mod and wonder how much improvement it brings to the sound pf the 5998 +E80CC combo.  One problem I have with the 5998 +E80CC is that the gain is a bit too high and I have only a small play in the volume knob.

I'm using the Beyer T90 as my main set of cans.  My other set is a Alessandro MS2i which doesn't match well with the Crack.

[onelivewire]

It's a very noticeable improvement with the e80cc resistance mod. I only decided to try it was after A/B'ing kscwuzhere's mod. I still don't prefer the e80cc to my Mullard ecc82 on my T1's, but for the 650s the difference made the e80cc a real winner IMO.