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October 17, 2021, 11:45:46 AM

Author Topic: Tube Rolling w/Crack  (Read 570565 times)

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Offline larcenasb

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Re: Tube Rolling w/Crack
« Reply #2370 on: September 19, 2021, 03:56:05 PM »
Thanks Paul & monsterdonkey.

Paul, this is the only tube I have (of many) that exhibits crackling sounds, so I'm hoping my solder joints are all good (my Crack has been running perfectly since 2014). I cleaned the tube pins with steel wool and the crackling went away!

So, I'm continuing running the tube for 100 hours. About 9 hours in now, the hiss sound in the left channel is very low. It's now at 1.5/10. Will update after 50 hours. Thanks again for your help. :)

Offline larcenasb

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Re: Tube Rolling w/Crack
« Reply #2371 on: September 24, 2021, 09:12:15 AM »
Update on 12AU7 left-channel hiss:

So, to recap, after 2 hours the hiss volume decreased and there was a short episode of crackling. Cleaning the tube pins seemed to fix the crackles.

Now, the hiss has been a consistently low volume. But after 25 hours, the hiss started gradually getting louder (lasted about 10 seconds), then some crackling occurred (lasted 5 seconds), then the crackles went away and the hiss went back to the earlier low volume. This was all just in the left channel; the right channel has no problems.

Are these new details indicative of anything in particular, just a bad tube maybe?




Offline Tom-s

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Re: Tube Rolling w/Crack
« Reply #2372 on: September 24, 2021, 10:51:32 AM »
Do voltage checks with that tube. Let us know. These can help pinpoint the problem.

Offline Paul Birkeland

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Re: Tube Rolling w/Crack
« Reply #2373 on: September 24, 2021, 12:12:59 PM »
Have you left the amp on since the 19th? 
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline larcenasb

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Re: Tube Rolling w/Crack
« Reply #2374 on: September 24, 2021, 12:34:58 PM »
Hi Tom-s, I can try to do the voltage checks this weekend.

Hi Paul, I was home all day on the 19th and 20th, so ran it for 24 hours. Besides that, I've just been running it when I can.

Here's my log:

9/18 - 2 hours
9/19 - 24 hours
9/22 - 5 hours
9/24 - 3 hours

Total so far: 34 hours

Offline Paul Birkeland

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Re: Tube Rolling w/Crack
« Reply #2375 on: September 24, 2021, 12:42:15 PM »
OK.  Turn it on now, then leave it on till Tuesday and let us know how the noise is after that.
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline larcenasb

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Re: Tube Rolling w/Crack
« Reply #2376 on: September 24, 2021, 12:52:13 PM »
Alright, will report back on Tuesday. Thanks, Paul.

Offline larcenasb

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Re: Tube Rolling w/Crack
« Reply #2377 on: September 29, 2021, 07:13:15 PM »
Update: Ran the amp nonstop from Friday to Tuesday and the hiss is still present along with intermittent buzzing. I then switched to another tube and no problems at all. So, I just got a noisy tube it seems? Nothing can be done to fix it?

Offline Paul Birkeland

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Re: Tube Rolling w/Crack
« Reply #2378 on: September 30, 2021, 05:01:49 AM »
That could indeed be the case.  Occasionally you'll get a tube that's more sensitive to external interference for one reason or another and a different tube won't pick up any noise.
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline larcenasb

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Re: Tube Rolling w/Crack
« Reply #2379 on: September 30, 2021, 01:29:54 PM »
Alright, it was still a good experience of troubleshooting and learning. Now time to enjoy my 6F8G tubes via an adapter. Cheers and thanks for your help, Paul.

Offline luczamic

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Re: Tube Rolling w/Crack
« Reply #2380 on: October 02, 2021, 10:41:59 PM »
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
« Last Edit: October 02, 2021, 10:46:30 PM by luczamic »

Offline Paul Birkeland

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Re: Tube Rolling w/Crack
« Reply #2381 on: October 03, 2021, 06:23:26 AM »
No, that's a new production Russian tube.  When people are recommending Mullard tubes, usually it's the old ones from Great Britain. 

https://www.ebay.com/itm/133890692536?hash=item1f2c81d5b8%3Ag%3Aa-cAAOSw3%7EBhFuQX&LH_ItemCondition=3000

Something like that would do the job.
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline larcenasb

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Re: Tube Rolling w/Crack
« Reply #2382 on: October 03, 2021, 06:32:19 AM »
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 :)

Offline luczamic

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Re: Tube Rolling w/Crack
« Reply #2383 on: October 03, 2021, 10:36:22 AM »
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 :)






Offline Paul Birkeland

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Re: Tube Rolling w/Crack
« Reply #2384 on: October 03, 2021, 10:38:20 AM »
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?
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man