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February 25, 2020, 04:28:00 PM

Author Topic: Tube Rolling w/Crack  (Read 488089 times)

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Offline Paul Birkeland

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Re: Tube Rolling w/Crack
« Reply #2070 on: February 10, 2020, 06:15:18 PM »
Do also be sure that all your solder joints are 100%.  The amp will sound pretty bad if you have cold joints, and rolling tubes and hearing enormous differences is sometimes an indicator of cold solder joints.
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline legion1capone

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Re: Tube Rolling w/Crack
« Reply #2071 on: February 11, 2020, 04:42:07 PM »
Anyone else have any experience with the Sovtek 6AS7G? Not much mention of it hear.

Offline Tom-s

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Re: Tube Rolling w/Crack
« Reply #2072 on: February 11, 2020, 07:47:49 PM »
Because it's price is very high compared to NOS probably.
Here a 6N13S / 6H13C that's also out of Russia, looks and sounds good imo and saves you a lot of money.

https://www.ebay.com/itm/6N13S-6-13-6AS7G-RUSSIAN-100-TESTED-TUBE-NOS/283678599033?hash=item420c8fe779:g:4TsAAOSwoG5Z8FWl

Offline legion1capone

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Re: Tube Rolling w/Crack
« Reply #2073 on: February 12, 2020, 12:15:44 AM »
I feel with today's current prices of tubes $60 is almost considered the lower end for cost. I swear damn near all the tubes I've looked up recently have been $70-400 that most people recommend on here. It's a sad day for the wallet.

Offline Tom-s

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Re: Tube Rolling w/Crack
« Reply #2074 on: February 12, 2020, 07:46:52 AM »
Just to let you know. I have a fair amount of (on internet crazy expensive) tubes.

The price of a tube has little to do with the actual sound quality.

In my Crack i use my current favorite setup (since a few months) that cost me 12€ total.

I paid maybe 10€ for a CV2984 GEC power tube on a local antique market and 1€ each for a CV6/7193 (+-half 6SN7).
Most pricey part of this tube setup was the adapter needed from ECC82 to 2x 7193 at +-30€.

https://www.head-fi.org/threads/crack-bottlehead-otl.476650/page-650#post-15242293




Offline legion1capone

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Re: Tube Rolling w/Crack
« Reply #2075 on: February 14, 2020, 08:15:59 AM »
The Sylvania 6080wb and the mullard cv4003 are a great pairing for the hd6xx/hd650. It's rich and full sounding. Sounds good with everything. The 6080wb really brought that rich sound compared to the sovtek 6as7g. The sovtek really opens the soundstage up with more air, details and highs that are allowed to sing.
The other pairing I liked for my own preferences is the sovtek 6as7g with the Mazda 12au7a. Compared to the other preamp tubes I rolled in the Mazda with the right power tube is some good stuff! Soundstage is a bit wider, more micro details start to stand out, the highs are so good! Along with controlled and punchy bass.
I really love hearing background details and an open airy sound. I'm hoping to purchase some more power tubes soon to be able to find the perfect one for my tastes. I am a bit worried the hd6xx are not going to give me the detail retrieval Im hoping for. I'm hoping at least I can get them closer to my tecsun caogen headphones.

Offline legion1capone

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Re: Tube Rolling w/Crack
« Reply #2076 on: February 15, 2020, 01:05:30 PM »
Is the Svetlana winged c 6H13C and the sovtek 6AS7G the same tube?

Offline legion1capone

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Re: Tube Rolling w/Crack
« Reply #2077 on: February 15, 2020, 08:30:49 PM »
Just finished looking through all 139 pages of this thread. My eyes hurt time for bed.

Offline cddc

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Re: Tube Rolling w/Crack
« Reply #2078 on: February 18, 2020, 07:32:42 PM »
Just to let you know. I have a fair amount of (on internet crazy expensive) tubes.

The price of a tube has little to do with the actual sound quality.

In my Crack i use my current favorite setup (since a few months) that cost me 12€ total.

I paid maybe 10€ for a CV2984 GEC power tube on a local antique market and 1€ each for a CV6/7193 (+-half 6SN7).
Most pricey part of this tube setup was the adapter needed from ECC82 to 2x 7193 at +-30€.

https://www.head-fi.org/threads/crack-bottlehead-otl.476650/page-650#post-15242293

OMG....10€ for a CV2984 GEC  :o  It's a huge advantage living in Europe.

When I visited Germany last Christmas, I found GEC tubes rare and expensive on eBay.de as well, no advantage to eBay.com at all.

Maybe I should have spent some time to locate some antique market when I was there...too late now  :'(

Offline cddc

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Re: Tube Rolling w/Crack
« Reply #2079 on: February 18, 2020, 07:37:07 PM »
Is the Svetlana winged c 6H13C and the sovtek 6AS7G the same tube?

Not too sure about that.

I do own several 6H13C's. You can post some pics of their innards here, and people here can check if they're the same.

Offline attmci

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Re: Tube Rolling w/Crack
« Reply #2080 on: February 20, 2020, 03:59:58 PM »
OMG....10€ for a CV2984 GEC  :o  It's a huge advantage living in Europe.

When I visited Germany last Christmas, I found GEC tubes rare and expensive on eBay.de as well, no advantage to eBay.com at all.

Maybe I should have spent some time to locate some antique market when I was there...too late now  :'(
I got a used GEC 6080 for about $20 a while ago (east bay). :)

Offline attmci

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Re: Tube Rolling w/Crack
« Reply #2081 on: February 20, 2020, 04:04:49 PM »
Not too sure about that.

I do own several 6H13C's. You can post some pics of their innards here, and people here can check if they're the same.
Same.

Offline cddc

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Re: Tube Rolling w/Crack
« Reply #2082 on: February 20, 2020, 06:56:44 PM »
I got a used GEC 6080 for about $20 a while ago (east bay). :)

You need good luck to score desired tubes on east bay...congrats

Offline tvr2500m

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Re: Tube Rolling w/Crack
« Reply #2083 on: February 21, 2020, 09:06:58 AM »
When is a tube out of range? Tubes have a large number of operating characteristics and parameters, as well as the different physical and mechanical bits. Circuits can have some range, more and less, of operational latitude to operate a tube under.

I bring this up around a specific curiosity of the Crack's output tube. The 6080 and 6AS7G have identical electrical characteristics, and they differ in packaging. I see the 6H13C and 6H5C (using Cyrillic here) typically called, or often treated as, direct substitutes for each other and to the 6080/6AS7G. They all look very close on the datasheets. Calling out the Gm, the 6H5C is quite a bit lower than the others - 5,000 vs. 7,000. What difference might this transconductance difference make in the Crack?

What prompted me to post this is someone mentioning to me recently that they've heard people report the GEC 6AS7G sounds as good or better than the Western Electric 421A/5998. Looking at the data sheet, the WE 421A has a Gm of 20,000. Isn't that a large Gm difference from the 6080? Could the tubes be direct subs in the Crack?

I really like the SED 6H13C and 6H5C. I can't hear a difference between them.

Offline Paul Birkeland

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Re: Tube Rolling w/Crack
« Reply #2084 on: February 21, 2020, 09:13:50 AM »
Changes in transconductance will alter the output impedance of the amplifier.  A whole lot of fuss has been made about the 5996 vs. the 6080, but we are talking about an output impedance of ~90 ohms vs. ~120 ohms, so YMMV.

With the Speedball installed, there is a great degree of flexibility when rolling tubes.  You'll always know that the output tube will be running at 30mA per triode, and the cathode voltage will settle where it needs to go in order to do that.  What you have to be careful of is putting a tube in there that brings the grid to cathode voltage too low, which could cause the output tube to draw some grid current and will collapse the performance of the amp.
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man