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Old 9th July 2008, 05:17 PM   #1
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Default Wing-C 300B tubes and opinions

Wind C 300B tubes - where to find them - reliable source ....

also - any opinions related any other 300B tube - which one is the best to use - the output transformers would be from Bartolucci, driver 6SN7GT and input tube 27.....thanks...in advance
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Old 9th July 2008, 05:35 PM   #2
kevinkr is offline kevinkr  United States
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Default Re: Wing-C 300B tubes and opinions

Quote:
Originally posted by sunrise
Wind C 300B tubes - where to find them - reliable source ....

also - any opinions related any other 300B tube - which one is the best to use - the output transformers would be from Bartolucci, driver 6SN7GT and input tube 27.....thanks...in advance

AKA Svetlana 300B - I've used both the original SV branded types and the =C= and frankly they are the least reliable 300B I have ever encountered. I last purchased a pair in 2002, and have barely used them. The problem is that even in the type III - the last ones I purchased, the filaments have a tendency to get out of alignment and arcing between the filament and grid occurs frequently. Unfortunately I've also had some short filament to grid. A few lost emission which was extremely puzzling as these were all low hour tubes run at nominal filament voltage, and conservatively operated. (60mA/400V) Out of a dozen or so I have owned about 9 have failed - most within a couple of months. I can't speak to later production, but I am not sure at this point whether or not they even still make it. I regard all of their 300B with deep suspicion, and will never buy them again. These were used in both SE and PP amplifiers. (And the last good pair were briefly evaluated in the SE amp mentioned below which I built in 2004.)

In addition they couldn't hold a candle to the JJ or WE sonically speaking. Harsh and gritty sounding in any SE amplifier I tried them in by comparison to JJ or WE..

I would recommend the JJ based on my personal experience and that of others I know.. EML makes several good ones as well. TianJian (TJ) makes some nice sounding globe types with meshplates. The WE 300B is very nice but rather more expensive than even the KR types.

The EH 300B is ok, the Sovtek IMO less so, both are relatively inexpensive and a safe starting point.

I am running older JJ 300B purchased around 2000 - 2001 so my experience may differ from those who bought later production. Mine have been trouble free and sound very good in comparison to the others I have been able to try recently.

Note most 300B have 1.2A filaments, the JJ 1.5A, and some KR even higher.

Depending on budget my first choice might be the current production WE 300B. I'd also like to try the TJ globe meshplate in my amplifier, but have not ponied up the courage to try them - they do have a good reputation for reliability.

My amplifier is 6J5 input, 6SN7 SRPP to 300B SE output stage running at 400V, 70mA. (Adjustable from 50 - 100mA) Separate CCS for heating each 300B filament. Independent tube regulated supplies for each driver circuit and power stage are used. (4 total) Coupling caps are Vcaps, resistors Holco, and opts are custom 3K:4, 8 ohms with about 45H primary inductance (IIRC) and rated for 100mA plate current. The amplifier has very extended HF response, IIRC -3dB well above 80kHz. Bass performance is rather good too.

Bartolucci makes great transformers (I've worked with a couple) and these should provide great performance for your project.
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Old 9th July 2008, 06:35 PM   #3
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kevin - great - this is what i was lookign for - thanks for the reply....

i wanted to find Wing-C's but they are problematic to find - current production of the JJ's i can find without a problem - and if you say that they are good also than my problem is solved....

can you also recommend (maybe) some other type of the transformers - other than Bartolucci (and Sovtek - which together with Bart. seems to be one of the best for the given money...maybe Lundahl or One Electron or something)....

i am searching for really great iron for the reasonable money and also really great tubes - it seems to me that JJ's are the right choice....
thanks again
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Old 9th July 2008, 07:29 PM   #4
kevinkr is offline kevinkr  United States
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Quote:
Originally posted by sunrise
kevin - great - this is what i was lookign for - thanks for the reply....

i wanted to find Wing-C's but they are problematic to find - current production of the JJ's i can find without a problem - and if you say that they are good also than my problem is solved....

can you also recommend (maybe) some other type of the transformers - other than Bartolucci (and Sovtek - which together with Bart. seems to be one of the best for the given money...maybe Lundahl or One Electron or something)....

i am searching for really great iron for the reasonable money and also really great tubes - it seems to me that JJ's are the right choice....
thanks again
Depends on where you are located, but imo Bartolucci makes great iron, very pricey here in the USA. Other suspects to look at should budget permit are Japanese products from Iso-Tango, Tamura (particularly the FS-5002) and Hashimoto - these will be amongst the finest available. In the USA Magnequest, and Electra-Print get my recommendations, Sowter in the UK, and Lundahl in Sweden.
James makes very good transformers at their respective price points as well. You have many good choices in fact.
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Old 9th July 2008, 07:44 PM   #5
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yes.....indeed..... i am in Europe - so probably i will go for Bartolucci or Sowter.....they were my primary choices.....and if not, after them, Lundahl as a third choice.......
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Old 9th July 2008, 10:39 PM   #6
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For SE the Sowter SA08S (3.5K for 300B, shrouded version) is built to a standard to inspire confidence, and sounds beautiful.

http://www.sowter.co.uk/specs/sa08.htm

they've been building it for years.

I have the 1998 JJ 300B too, and they're still working fine and sounding splendid. Kevin is certainly doing the right thing with filament heating. Current-only control of the filament is the only way to go with these, not just because the sound is infinitely better, but mine ran for three years before failing below 4,85V across the filament. The line-voltage variation with ac heat caused them to cut in & out, as well as sounding less involving and muddier. With current control, you get very slow startup (eliminating mechanical damage caused by surges), and setting the current to give 4,95V has not required adjustment in four years.

New DHT heater

some buyers of newer JJs report a drop in quality, with thin glass and poorer sound. With these, like the Sovteks, the degree of improvement in sound is even greater when heating with current drive.
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Old 9th July 2008, 11:09 PM   #7
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have someone maybe the link for the Triode Dick filament supply mentioned in the link Rod provided??

So, in fact - i need "voltage limited current source"...... hmmm, man...this gives me new horizon to think about.....o.k. - thanks ....i will print the sch's and study them...
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Old 10th July 2008, 04:53 PM   #8
sgerus is offline sgerus  United States
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Kevin,

Can you provide some details about your 6j5-6SN7 SRPP input / driver stage?
I would like to know the input sensitivity and how you coupled from the 6J5 to the 6SN7, and from the 6SN7 to the 300B.

Thanks, Scott
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Old 10th July 2008, 05:21 PM   #9
kevinkr is offline kevinkr  United States
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Hi Sqerus,

It's just conventional RC coupling.. 6J5 runs at about 7mA with a 27K plate load resistor off of a 400V supply. Cathode resistor is unbypassed 1K resistor. SRPP is also running off of 400V supply, grid input resistor is 332K to ground, cathode resistors 1.21K with no bypass. The 300B grid resistor is 100K... Maximum output voltage is about 195Vpp, and with cathode bypass is just a touch higher - enough to drive the 300B to full output in my amplifier. Input sensitivity for full output is slightly less than 1Vrms IIRC. (It's been a long time since I measured and the data is lost in a filing cabinet somewhere.)

I designed this thing 9 yrs ago and built a number of them commercially - in fact there is one on audiogon for sale right now..

The amplifier performs very well and sounds good, a number of friends have built clones..

Were I to do this design again I would probably use an IT and aim for a minimum of 3dB of headroom in the driver stage - this one has about 1dB and I suspect linearity suffers slightly at the extreme. (The output stage is the dominant nonlinearity in this design.) THD at 10Wrms was 5% - however this was running over 90mA of bias at 400V and not recommended for good tube life. Commercial expediency and my own personal biases at the time dictated the original design. My clone dates from 2004 and is a slightly improved (in limited ways) version of the commercial offering, I did not have the available funds to build a significantly different design at the time.

I don't currently offered detailed schematics or other information on this design, although I am debating eventually offering it in libretto form on lulu where I have some other material on offer..
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