Tube Rolling w/Crack

Not at all. The cathode follower has no voltage gain, so slight imbalances like that won't be audible like they might otherwise be with a standard voltage amplifier.
 
Fantastic, thanks PB!  I was going to say, I have some other mismatched power tubes and never noticed an imbalance.  Looks like I have some reading to do on cathode followers...
 
I'd like to update my comments from a couple of weeks ago:

After replacing both tubes in my Crack (w/Speedball) and burning them in for a while, I believe there is a substantial improvement in the sound quality. The sound stage is broader, the details are crisper. In short, the sound is spectacular. I almost forget I'm wearing headphones. (Sennheiser 6XX.)

New tubes are both NOS from 1965. 12AU7 by La Radiotechnique (French division of Philips, I think) and Tung Sol 7236 power tube.

(Since the world of available tubes seems nearly infinite, I have decide to limit what I am willing to purchase to tubes from the year I was born. I have a Svetlana 6N13S on the way from Ukraine...doubt it will be better than the 7236 consistently but it will be fun to explore.)

It's sooooo cool to be able to find unused tubes that are more than 50 years old. (Assuming the sellers are telling the truth about NOS status.)
 
Hi Everyone,

First of all, I'm enjoying my crack and speedball each day. It definitely was one of the best purchases I've made for my setup at home. Everything has been working nicely for the last little while.
I'm interested in changing out the tubes to change the sound a bit. I am actively reading the tube rolling thread, but going through 120 pages of comments will take time.

I've noticed that the highs with the crack and speedball seem to be a little harsh to my ears. Things like cymbals, and sibilance (Like the  "shhhh" sound) are sort of painful to my ears.
After a little while my ears do get used to it, but I was wondering if anyone else had this experience, and if changing to a different tube eased these highs?
 
Sorry, I forgot to mention that!
Headphones are the Sennheiser HD 6xx/650, and my source in this case is a Topping D30 DAC connected to my PC via USB.
I haven't connected it to my turntable's phono stage yet. I'll be testing that out tonight to see if the DAC is causing the harshness.
 
I had that same problem. I also have HD 650, Crack with Speedball. I determined it was a combination of the DAC and tubes I was using. I tried a Topping D50 and it hurt to listen to it for the same reasons as you're describing. I also found I prefer the 6080's and RCA 12AU7 clear top for tubes. This is my experience, your mileage may vary.
 
I'm going to get in trouble for asking this but did you notice the "harshness" before or after you installed the speedball?

Let us know how the phono session goes.
 
Haven't had a chance to test out the turntable last night (was too tired), but will do it today.
However, if the Crack + SB combo only hurts with the DAC like BZ58 said, then I can live with that, as it's not my main source for listening to music.

@Natural Sound, I only noticed the harshness after installing the speed ball. I did some googling, and it seems that some people experienced something similar.
However, they didn't mentioned what their sources were. I have the same songs on vinyl that I was listening on my PC through my DAC.
So I'll make the comparison tonight and report back.
 
It is definitely the DAC, or the combination of everything together.
The same songs on vinyl are much more pleasing. No harsh highs, or harsh silibance!
My ears feel extremely comfortable now :D

It’s too bad the DAC produces the harshness, but I can live with it.
Thanks guys!
 
That's unfortunate. It would seem just because something measures well, (thanks ASR) doesn't mean it will sound pleasing to the ears. I personally have the mimby and love it. You could swap tubes and it may curb your frustrations with the DAC, or you could sell the DAC and get something less harsh. Good luck!
 
Hey!  So I was just looking into tube rolling and read the stickied post and a few others for info.  I've been struggling to find info on what all the different letters and numbers in the tube names mean, and how to determine if they're compatible.  I was looking at some Mullard CV2984 6080 6AS7 tubes that I think are compatible, but wanted to confirm here first. I also had a few other questions, and any help would be appreciated!

-What does the info on what all the numbers/letters mean as far as compatibility goes?
-What is the difference between military vs nonmilitary tubes?
-Does the speedball installation make a difference with tube compatibility?
-Would accidentally using an incompatible tube cause damage to the amp or voltage discrepancies?

Thanks
 
Jake1 said:
-What does the info on what all the numbers/letters mean as far as compatibility goes?
That's a bit of an overly general question.  You'd have to ask the specific differences between two specific tube labels to ask a question that's more answerable.

Jake1 said:
-What is the difference between military vs nonmilitary tubes?
Sometimes there isn't any beyond a different box and some different printing on the tube. Sometimes there is an extra mica support inside the tube, sometimes there are other modifications for better shock/vibration performance.  This is dependent on the tube itself and what the datasheet might or might not call out.
Jake1 said:
-Does the speedball installation make a difference with tube compatibility?
Nope.
Jake1 said:
-Would accidentally using an incompatible tube cause damage to the amp or voltage discrepancies?
Yes!
 
Thanks for all the info!  Also is the  Mullard CV2984 6080 6AS7 tube compatible with the crack?  And how do you check the compatibility between tubes and amps?
 
Jake1 said:
Thanks for all the info!  Also is the  Mullard CV2984 6080 6AS7 tube compatible with the crack?  And how do you check the compatibility between tubes and amps?

Yes it is. The amp takes 6080/6AS7 tubes. You can read the first page of this thread to see which tubes you can use with the crack.
 
For compatibility, check the first page. Search the web for equivalents. Use the search on this forum for previous threads concerning the same question/tube. If you're still in doubt, ask here.
 
In my limited experience researching tubes and buying a few: on eBay some tube sellers will include multiple tube identifying numbers for a tube that's obviously only one of those. Not necessarily trying to deceive but rather including the identifiers of tubes that can usually substitute for each other with only modest differences between then. The issue is that what a seller might thing is a reasonable substitute might not be in your own particular application so you have to do a little more homework.

I'd love for someone more expert to respond to my interpretation of the situation.
 
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