Tube Rolling w/Crack

[Tom-s]

It is, after you sold 1 kidney 

[attmci]

It is, after you sold 1 kidney 

LOL  Then you have to go back to page 90 (http://bottlehead.com/smf/index.php?topic=663.1335). Two paralleled tubes can compete with any prime tubes per my test.

PT-3 is a nice little power transformer. PT-7/PT-10 is even better.

A little bit history can be found here:

http://www.audioasylum.com/cgi/t.mpl?f=bottlehead&m=135369

And here: "The power trans can deliver 3.8A AC to the 6.3V heaters. Right now the 6080 draws 2.5A and the 12AU7 draws 0.3A. So right now the total draw is 2.8A. One could change to a 6SN7 (0.6A heater) by punching out the socket mounting hole and wiring in an octal socket. Or just do it the easy way and use a 6CG7 in the existing socket with the heater pins rewired from 9 and 4/5 tied to 4 and 5. 12BH7 should be pretty easy to do as well." -Doc

[monsterdonkey]

And oh gee, suddenly this Crack sounds f-balls amazing again. Modding for the sake of it is good, but just now I learned a lesson.  Back to it.

[ideal.hat]

Hello

Which tubes did you replace with the stock tubes?

[jaysbob]

What a difference E80CC's make, been listening to a couple different examples for a week or two now. So much smoother and more articulate compared to anything else I've tried, huge well controlled low end and crisp clear highs and mids.

I've tried a lot of tubes in my crack. Including some 6f8g's and 6fq7's but nothing has immediately taken my breath away like the E80CC's have. A couple 6sn7's I've tried have come close but the examples I had that sounded best were also highly microphonic and none of the E80CC's I've tried have had this problem. It feels like as significant an improvement as the speedball was over the stock crack. I can't get the headphones off of my ears.

I'd be interested if anybody has any picture of how they implemented a resistor switch on the small speedball board.

It's just too bad that NOS E80CC's seem to be a vanishing commodity.

[JamieMcC]

There is a lot of info and a few pics of the resistor mod in this thread

http://bottlehead.com/smf/index.php?topic=5989.0

[Lawrence Ho]

Hi everyone,

I completed my first build of CRACK recently and have been enjoying the reward very much ever since!

Not so surprisingly, I am already in pursuit of NOS tubes but found myself lacking the knowledge required.

Even though I have done a lot of readings over the past week, there are fundamental questions that hopefully can be answered here.

1.) When buying NOS, what parameters exactly I should check? [Gm, IA?] 
2.) Are there any matching of parameters need to be done when buying one single tube [not a pair]?
3.) http://www.ebay.com/itm/RCA-6AS7-G-Vacuum-Tube-Results-2680-3450-/182440130837?hash=item2a7a477915:g:5BwAAOSw2xRYkMxU This tube, the seller says test result = 2680/3450, does it matter these two value aren't close?
4). What else i need to be aware of? Any suggested readings/guideline for beginners like me?

p.s http://www.ebay.com/itm/Tung-Sol-5998-2399-421A-replacement-/272523578533?hash=item3f73abcca5:g:6oEAAOSwNnRYfGrz do you guys think it is a good deal? 5998 is so expensive these day...

Thanks so much in advance!

Lawrence

[attmci]

Hello

Which tubes did you replace with the stock tubes?

Bad tubes. 

[Lawrence Ho]

Hi everyone,

I completed my first build of CRACK recently and have been enjoying the reward very much ever since!

Not so surprisingly, I am already in pursuit of NOS tubes but found myself lacking the knowledge required.

Even though I have done a lot of readings over the past week, there are fundamental questions that hopefully can be answered here.

1.) When buying NOS, what parameters exactly I should check? [Gm, IA?] 
2.) Are there any matching of parameters need to be done when buying one single tube [not a pair]?
3.) http://www.ebay.com/itm/RCA-6AS7-G-Vacuum-Tube-Results-2680-3450-/182440130837?hash=item2a7a477915:g:5BwAAOSw2xRYkMxU This tube, the seller says test result = 2680/3450, does it matter these two value aren't close?
4). What else i need to be aware of? Any suggested readings/guideline for beginners like me?

p.s http://www.ebay.com/itm/Tung-Sol-5998-2399-421A-replacement-/272523578533?hash=item3f73abcca5:g:6oEAAOSwNnRYfGrz do you guys think it is a good deal? 5998 is so expensive these day...

Thanks so much in advance!

Lawrence

Appreciation to the member who answered my questions! (also apologizes for not remembering your name as the reply is gone somehow)

I wanted to come back with more questions after doing some study on monophonic problem just like you suggested. But they do not matter anymore,

have given up on that tube already.

Not sure whether you will read this, but I still want to send you my gratitude.


Lawrence

[monsterdonkey]

I replaced the stock GE 6080 with a Chatham 2399, and the unbranded 12AU7 with an RCA clear top 12AU7A. For a while I preferred the look of the st shaped Chatham tube. It looks impressive sitting there on the cabinet. But I found the sound to be harsh and lacking bass. Maybe a little cold. I have the Crack plugged into the tape monitor output on my NAD C740, which bypasses the eq. Straight signal into HD 600s -what could go wrong? But I wasn't listening as often as I had been in the past.
The other night I plugged the GE back in (left the RCA) and fired up QotSA - Like Clockwork. The richness and warmth and bass I'd been missing was back and the experience was delightful. I've verified my drunken findings in the sober light of day by listening to some other things on the original tube and it still sounds great. If I get a chance maybe I'll do an A/B test with my bias tuned towards the workhorse 6080 rather than the pretty 2399 this time.
My Crack has the Speedball upgrade and some big M-Caps capacitors.

[Pg]

Hi Did anyone ever figure out the reason for the Crack loud buzzing at the minimum volume level?  Once I move the volume off of mimimum (zero) the loud buzzing goes away.

[Pg]

I am puzzled with my Crack with Speedball. If I use a 6080 tube I get no buzzing but if I use a 7236 or 421atube I get buzzing when the volume is at minimum. Anybody run across this problem? If yes what tubes are you using that don't buzz (6AS7G?)?

[Doc B.]

Try cleaning the tube pins.

[attmci]

I replaced the stock GE 6080 with a Chatham 2399, and the unbranded 12AU7 with an RCA clear top 12AU7A. For a while I preferred the look of the st shaped Chatham tube. It looks impressive sitting there on the cabinet. But I found the sound to be harsh and lacking bass. Maybe a little cold. I have the Crack plugged into the tape monitor output on my NAD C740, which bypasses the eq. Straight signal into HD 600s -what could go wrong? But I wasn't listening as often as I had been in the past.
The other night I plugged the GE back in (left the RCA) and fired up QotSA - Like Clockwork. The richness and warmth and bass I'd been missing was back and the experience was delightful. I've verified my drunken findings in the sober light of day by listening to some other things on the original tube and it still sounds great. If I get a chance maybe I'll do an A/B test with my bias tuned towards the workhorse 6080 rather than the pretty 2399 this time.
My Crack has the Speedball upgrade and some big M-Caps capacitors.

Wow,  a GE 6080 beat a 5998.

[monsterdonkey]

Wow,  a GE 6080 beat a 5998.

Yeah. It shows how subjective this stuff can be sometimes. It also may expose the limitations of my gear.