Tube Rolling w/Crack

Hi guys,

First of all, I'm pretty new to all this :) I don't really know anything about tubes and rolling them :)

I'm coming from HD598... which stopped working earlier this year. I found that HD6xx were on sale, and since I heard a lot of good things about these headphones, decided to order them.

When I got them I realized they need an amp.

Back in the day I once heard a tube speaker amplifier which absolutely blown me away. It was Jolida.
In any case, figured that if I'm going to get an amp for the headphone, I might as well go with tubes. So here I am with the crack :)

I was very excited to hear that amp. And after I build it I absolutely loved the sound. Then came the speedball...
I'm not sure if I did something wrong when building it. All the voltages are ok, the amp is dead quiet when nothing is playing but I just found it too bright, my ears would fatigue very quickly.

I decided to remove the small board, but I also read that this issue can be fixed with tubes, especially Mullards? The thing is I don't know where to find them, there are old and new and I'm lost.

Would anybody here be able to help me to find the right tubes? I'm after that warm tubey sound but also want to keep the speedball as I can hear the difference in detail and clarity.

I'm living in Australia so these aren't that easy to find. I ordered one Mullard tube from here thevalvestore com au , but I'm not even sure if that's the right one... :)



Any help and advice will be much appreciated

Thanks
Michal
 

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Hi there, welcome to the club!

You can search auction sites for the crème de la crème Mullards. Just make sure the seller posts the test results and has 100% feedback, of course. Here are some details you need to know about Mullards you're looking for:

- Can be designated as a 12AU7, ECC82, or CV491
- Made in the Blackburn plant in England during the 1950s
- Construction: 17mm long plates, has a square getter or O getter on top
- Date code: K61 (also, you can look for K62 versions, which were made after)

When I search auction sites, I just search "k61 tube" to lasso in the most listings. Some people like the CV4003 or other types, but most collectors, including myself, have found the k61 really is the very best of Mullard 12AU7 tubes. It sounds closer to an octal type than any miniature tube I've heard: it has a big, effortless, tonally rich, and natural sound.

The Mullard you got may be good, I haven't heard it...Let us know. It's a new-production tube and was made in Russia though. Mullard is famous for their made-in-England tubes from WWII-era and the 1950s, so if you can deal with the prices, it's worth having a listen while they're still available. Because, obviously, these older tubes aren't being made anymore and will eventually become extinct. In that sense, we're lucky we live in this age to be able to enjoy them. :)

Some other options:
- Amperex 7316 Long Plate Foil Getter (also rich and warm, but not to the extent of Mullard, also pricey)
- RCA 1950s long black plates square getter (also rich and warm, more rolled off treble, can be found significantly cheaper)
- Raytheon, RCA, Ken-Rad, National Union, Tung-Sol 6SN7GT [using a 6SN7 to 12AU7 6.3V adapter] (WWII-era octal tubes that have nice bloat in the upper bass and lower mids compared to most 12AU7 types, RCA and Raytheon can be found significantly cheaper, the Tung-Sol is the other consensus holy grail tube like the Mullard that sounds wonderfully natural and easy to listen to but is going for insane prices these days)
- Use a 6AS7G type output tube (I've found this has a more drastic change on the sound compared to input tube rolling, input tubes can slightly color the sound better though, the 6AS7G is warmer and more spacious sounding in my experience compared to 6080 types)

Be warned this obsession has become a black hole for many of us. Perhaps, you'd be best served to just take out the Speedball, if you loved that sound already... Cheers :)
 
Wow, thanks guys for the advice... and a warring :) ... that being said... are these any good?    :D (see attachments)

I will definitely let you know how's that Mullard that I already ordered, but I don't have high hopes after Paul's replay.

I will keep an eye on for the ones you mentioned, larcenasb, thanks very much for your extensive replay

I've seen the mention of CV4003 in different posts, but the one I found seems to be "new" as you can choose different options? Like Low Noise & Microphonics? So I'm not sure if that's the right one.

The other one I found when I looked for K61 is 1958 Mullard, but it's labeled as HEATH. I've seen posts that the NOS ones are the ones to look for?
All of this is so confusing :D

To make things worse, should I be looking for a different power tube as well? It's getting pretty expensive.. :/
I just really want to learn to love that Speedball, so I'm willing to give few tubes a go, to see If I can find some middle ground, but at the same time, don't want to go too crazy.

After all, this whole thing started to replace 10 years old $150 headphones, and now I'm more than $900 in already :D ... one step at a time they say :)





 

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Why do you want to spend hundreds of dollars on tubes?

I linked you to an $8 used Mullard, why don't you buy that and see if you like it first?
 
Tube rolling can be fun and costly and all that, but as the differences can be quite subtle (I’ve found I like tubes I thought I didn’t like on different days) why not try adjusting the tone controls or equalizer on your source machine and see if you can get it closer to your preference that way?
 
Hey all, i finished my kit a few weeks ago and am looking to roll around. I want to start with some of the tubes i yave left over from my guitar days and when searching i came across this guy.

A JAN Philips 5751

Since this is a 12ax7 type normally i would try, but here is an interesting thing about it:
The 5751 is not a true 12AX7, but is often used in place of a 12AX7. They should have approximately 70% of the gain of a 12AX7, and are often used to quiet down guitar amps that have too much gain. If you have gain to spare using a 5751 tube will greatly improve your overall tone without making your preamp excessively clean.

With this said, is this something that can be safe on a BHC + SB or is it still going to be too much?

Thanks for the help!
 
Thanks for confirming guys, I figured the lower gain 5751 would still be too far off.

I bought a few of these for $15-20 a piece and now they are much rarer. I most likely will sell them and grab what i need.
 
Re: crackling in tubes, what's your opinion on reflowing the solder inside of the pins? Let's say I have a power tube with thick pins that crackles and other tubes don't (so it is not an amp issue). Cleaning pins does not help

Is sucking the solder with vacuum and putting a new one a good idea? I've heard some people do it.
 
Reflowing tube pins is done more often with older four pin DHTs, as they were more susceptible to the joints inside the pins oxidizing with time and the glass coming loose in the base, allowing stress on the pin connections. I might be inclined to install the 6080, invert the amp, fire it up and wiggle the socket connections at each pin while listening for the noise. Obviously you want to use headphones you can afford to sacrifice for this kind of test. If you can make it happen by working the contacts it might be worth attempting a reflow - or you may have located a bad contact between the pin and the socket. Chances are good that the crackling is due to some other internal, mechanical issue in the tube.
 
Oh, the solder in the pins themselves?  I have done this a bunch on 4 pin tube bases, but never on an octal that I can remember.  You could touch the tip of your iron to each socket pin and let the solder reheat and flow out a bit more. 
 
I have a Garage 6SN7 to 12AU7 and it works perfectly. I've rolled many 6SN7 tubes.

I have Siemens C3G tubes. https://www.tubedepot.com/products/siemens-c3g-pentode

Can I use https://www.ebay.co.uk/itm/201814708334 to adapt it to 6SN7 and then to 12AU7 via Garage adaptor? Or does it look unrealistic?
 
ipetruk said:
I have a Garage 6SN7 to 12AU7 and it works perfectly. I've rolled many 6SN7 tubes.

I have Siemens C3G tubes. https://www.tubedepot.com/products/siemens-c3g-pentode

Can I use https://www.ebay.co.uk/itm/201814708334 to adapt it to 6SN7 and then to 12AU7 via Garage adaptor? Or does it look unrealistic?
Click to expand...
We use both halve of the 12AU7, so a triode strapped C3G will not be a suitable substitute. Depending on what's going on in the adapter, you could cause serious damage to the amp or the 6080 if you tried this.

The C3G has way too much gain for the Crack circuit anyway. 
 
Hey all, recently bought my first tube to try tube rolling with, a Tung Sol 6520 with the domino plates on ebay. The seller said it had plenty of life in the listing, however when I plug it in the left channel is there but almost inaudible. If I crank up the volume all the way I can hear it better but then the right is way too loud. Volume is fine in both channels with the original 6080. Does this mean one of the triodes is dying and it's a bad tube, or is there something I can do? Thanks
 
Hey there! I recently sold a working Crack w/ SB. The buyer says that he is getting very low volume. I was wondering if this could be a bad tube? I did give him extra power and input tubes that he could try. I'm guessing I should ask him to try all tube configurations to see if that helps? Any other suggestions? As mentioned, I know this amp worked fine when I listened to it before selling it last week. I am wondering if one of the tubes went bad or was damaged in shipping. Makes me nervous as I have never sold anything that didn't work as intended! The Crack came pre-assembled to me, so I have zero knowledge or skills in diagnosing anything wrong with the electronics but I suspect that it's either tube-related or maybe a configuration error. Any help would be greatly appreciated!
 
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