Tube Rolling w/Crack

[Rossputin]

I've decided that there are far too many possible tubes one could put in a Crack and I wanted to limit my selection so I've decided to only buy tubes from the year of my birth (mid-1960s). It's surprisingly easy, actually, even for NOS tubes, but at least it puts some guard rails on what could easily be a big money-pit addiction.

So far got a 12AU7 from La Radiotechnique and a 7236 from Tung-Sol. Have a Russian "Svetlana" 6NS13 on the way. Keeping my eyes out for a 5998 that isn't ridiculously priced.

Not sure I can hear a difference so far vs stock tubes. I think I can, but maybe it's because I think I'm supposed to. Still, it's quite fun.

[Raymond P.]

If you're new to tube rolling, like I am, and just want to hear a more than subtle difference in tubes, try comparing a Mullard CV4003 (box plates) with a, say, Telefunken 12AU7 (smooth plates). I find the Mullard to be too mid-centric, and the lack of top end frequency energy makes it sound unnatural. The Telefunken's mids have some of that holographic effect which I find very pleasing and overall is much more neutral. YMMV, of course.

-Raymond

[attmci]

If you're new to tube rolling, like I am, and just want to hear a more than subtle difference in tubes, try comparing a Mullard CV4003 (box plates) with a, say, Telefunken 12AU7 (smooth plates). I find the Mullard to be too mid-centric, and the lack of top end frequency energy makes it sound unnatural. The Telefunken's mids have some of that holographic effect which I find very pleasing and overall is much more neutral. YMMV, of course.

-Raymond

Among the dozens of various 12au7 tubes I had tried on a Crack, 7316 is the best driver tube for me unless you can afford these:

https://www.ebay.com/itm/LORENZ-ECC82-12AU7-LONG-WELDED-PLATES-HALO-GTR-SIX-TUBES-ULTRA-ULTRA-RARE-/132611879757?hash=item1ee048b34d%3Ag%3A%7EzwAAOSwtJFasDX0&nma=true&si=oPipPtWcTh6PNFsQgYUTDHO0ddw%253D&orig_cvip=true&rt=nc&_trksid=p2047675.l2557

[Doc B.]

is the best driver tube for Crack

It's very important to add "for me" to this kind of statement. Otherwise it is misleading.

[L0rdGwyn]

Question for Doc or PB if you would gents would be so kind - if I have a power tube with mismatched sections, one with a Mu of 5.0 and the other with a Mu of 5.4, would that translate to an audible channel imbalance in the Crack circuit?

[Paul Birkeland]

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.

[L0rdGwyn]

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...

[Rossputin]

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.)

[adydula]

I bought a new set of HD600's and they are indeed spectacular with the Crack w Speedball...
Simply magical!
Alex

[Blue]

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?

[Natural Sound]

What kind of headphones and source are you using?

[Blue]

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.

[BZ58]

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.

[Natural Sound]

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.

[Blue]

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.