Author Topic: Little Dot MkII: New tubes  (Read 269 times)

Offline Tenflare

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Little Dot MkII: New tubes
« on: December 04, 2017, 05:38:48 PM »
I've resolved to buy no more headphones, DACs or headamps in 2018 (My HD6XX will ship in March but it doesn't count). As such, my AV exploits for the next 12 months will be devoted toward other kinds of gear, AV furniture, room acoustics, rack mounting, and maximising the effectiveness & convenience of what I currently own with better wiring, etc.

I've been the proud owner of a Little Dot Mk II for about a year now. But I have neglected the rolling aspect of the entire tube sub hobby. The unit came with a pair of very nifty JAN-5654's which sound excellent. However, part and parcel with my 2018 resolution would be to endow the thing with other tube options.

Without messing with any internals, I know I can safely roll in the 6JI (driver tubes) and 6N6 (power tubes) families. My question, as a total tube noob, would be what should I buy and where should I look to get it?

Thanks guys.

 
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Offline Curlycat

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Re: Little Dot MkII: New tubes
« Reply #1 on: December 04, 2017, 06:37:36 PM »
Can't help you with which tubes to get, but I buy mine at
https://www.tubedepot.com/ (preferred)

also http://www.thetubestore.com/

Locally you can try Charles here on the forum. Great person to deal with!
Then there is Mr Valve in Pretoria, www.mrvalve.co.za

Offline capetownwatches

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Re: Little Dot MkII: New tubes
« Reply #2 on: December 04, 2017, 09:50:27 PM »
That LD uses the most obscure Chinese tubes. Not easy to find decent replacements.

US: 6AK5 = European EF95 = Chinese 6J1 = Russian 6J1B = Premium/industrial 5591

6N6 can be replaced by another 6N6 or Russian equivalent 6N6P - there are no other direct replacements.
Some say E182CC/ECC99 can be used but may require tweaking.

Check out one of the LD rolling threads for more info. Those boards make my brain hurt...
« Last Edit: December 04, 2017, 09:55:26 PM by capetownwatches »

Offline capetownwatches

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Re: Little Dot MkII: New tubes
« Reply #3 on: December 05, 2017, 12:19:53 AM »
That LD uses the most obscure Chinese tubes. Not easy to find decent replacements.

US: 6AK5 = European EF95 = Chinese 6J1 = Russian 6J1B = Premium/industrial 5591

6N6 can be replaced by another 6N6 or Russian equivalent 6N6P - there are no other direct replacements.
Some say E182CC/ECC99 can be used but may require tweaking.

Check out one of the LD rolling threads for more info. Those boards make my brain hurt...
https://www.head-fi.org/threads/little-dot-tube-amps-vacuum-tube-rolling-guide.563884/

700 plus pages...should keep you busy for a while.



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Offline fredeb

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Re: Little Dot MkII: New tubes
« Reply #4 on: December 05, 2017, 04:17:25 PM »
That LD uses the most obscure Chinese tubes. Not easy to find decent replacements.

US: 6AK5 = European EF95 = Chinese 6J1 = Russian 6J1B = Premium/industrial 5591

6N6 can be replaced by another 6N6 or Russian equivalent 6N6P - there are no other direct replacements.
Some say E182CC/ECC99 can be used but may require tweaking.

Check out one of the LD rolling threads for more info. Those boards make my brain hurt...
E182CC would require filament to be re-wired , or a socket converter .

I have some 6N6P's  .
...evolution is the gradual development and stratification of progressive series of wholes, stretching from the inorganic beginnings to the highest level of spiritual creation.
Jan Smuts

Offline capetownwatches

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Re: Little Dot MkII: New tubes
« Reply #5 on: December 05, 2017, 05:45:00 PM »
E182CC would require filament to be re-wired , or a socket converter .

I have some 6N6P's  .

Gotta make a plan to get to you one of these days - you have a pair of 6N23P-EV with my name on them, remember?  :drool:

Offline fredeb

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Re: Little Dot MkII: New tubes
« Reply #6 on: December 05, 2017, 07:43:27 PM »
;) It's probably gonna get more difficult , with silly season approaching , but I'm sure we'll get it together .
...evolution is the gradual development and stratification of progressive series of wholes, stretching from the inorganic beginnings to the highest level of spiritual creation.
Jan Smuts

Offline Ampdog

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Re: Little Dot MkII: New tubes
« Reply #7 on: December 07, 2017, 09:55:03 PM »
E182CC would require the whole socket to be rewired; other electrode connections differ from the 'classic' ECC82 style. Also, it was a computer valve, meaning that the main characteristics were low 'on' resistance (obviously high off-resistance). The amplification factor is not guaranteed to much better than +/- 30% - and in practice they do come out with that spread, even between the triodes in the same envelope. So good luck going 'rolling' those.

I don't want to sound like a broken record (do people even use that expression anymore - perhaps to say a track-slipping CD. And even that .... ) but valve rolling always leaves me with the suspicion that some think the designers did not now their job.  There is a reason why a certain valve was chosen/preferred!  But what with present spread in the characteristics/performance of even same number valves, it has become a hit-and-miss job to find the 'optimum' valve.

So I will leave it at that and quietly withdraw from commenting on the practice of valve switching - folks will simply do it one way or another despite any argument to the contrary. Perhaps just warning regarding different pin-outs.

Audio must be the only branch of engineering where lack of basics' knowledge is considered a superior form of wisdom. (Anon)

Offline charles

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Re: Little Dot MkII: New tubes
« Reply #8 on: December 09, 2017, 11:51:15 AM »
This week obtained some (>10) NOS J AN 5654W tubes.

On box:
some production numbers; JAN5654W; made by GE CO USA; date pkd 11/72; similar to CV 4010; (A)

These tubes are the same as the 6AK5W ones

I will sell these tubes
« Last Edit: December 09, 2017, 11:53:55 AM by charles »