- Posted by Tom §. on June 12, 2000 at 08:30:27:
I've been putzing around with the 6H30-Pi tube for the last week and I just thought I'd pass along my impressions. It seems like the 6H30-Pi is to the 6N1P as the 6N1P is to the 6DJ8/6922.Just some characteristics:
The 6H30-Pi has a glass envelope much like the EL-84 and 12B4 (although it's slighty taller and fatter than the 12B4). I ended up with three of the tubes and the sections of each tube performed within .5% (yeah, ½ of one percent) of each other for bias current/voltages and gain when used in circuit. The getter flash of the tube covers about 35%-40% of the glass envelope. One thing to note is that the gate to plate capacitance of the 6H30-Pi is 6pF. That's nothing to sneeze at if you want bandwidth.The circuits used for subjective sonic impressions:
I built a preamplifier with the intention of using it with the 6N1P. It only uses one tube in a grounded cathode configuration. The cathode resistor is 220ohm with a 220uF bypass. With the 6N1P the DC bias runs around 9mA with 200V from plate to cathode. With the 6H30-Pi the bias current is 23mA with 100V across the tube section. The dual mono B+ power supplies were designed for 260V at 10mA but the supply can deliver up to 50mA if needed. The heater current required for the 6N1P was 600mA and the closest readily available trannie was a hammond that was rated 6.3V@1 amp. The 6H30-Pi heater draws about 900mA at that voltage so everything is cool in the filament PS department (ugh).The comparison:
Since the circuit could accomodate both the 6N1P and the 6H30-Pi I decided to interchange them for some subjective sonic comparisons. I really liked the 6N1P. It had a nice, clear top end as well as solid bass. I imagine you could pound on that little tube for hours and you still wouldn't get any microphonics. A pretty goddamned nice tube for $4.With the 6H30-Pi plugged in, things got a bit more interesting. It had the same bass character of the 6N1P but the midrange and top end was just soooooo much more engaging and sumptuous. Not really "warmer" but just more convincing and enthralling. I can certainly see why Victor is integrating them into his products. The price to performance ratio is not as great as the 6N1P but hey, ya gotsta pay for da performance. $20 per tube from Triode Electronics seems quite reasonable when compared to the prices being tagged on rare NOS tubes.
Tom §.
- Re: Music in a bottle: 6H30-Pi Paul Joppa 21:42:34 06/12/00
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- In Reply to: Music in a bottle: 6H30-Pi posted by Tom §. on June 12, 2000 at 08:30:27:
> > I really liked the 6N1P ... I imagine you could pound on that little tube for hours and you still wouldn't get any microphonics.
I was just recently playing with an amp with a 6N1P driving a 300B. The 300B output made more output noise when thwacked than the 6N1P, even though it was the driver stage. Excellent tube for microphonics!
Any sense if the 6H30Pi is equally silent when kicked?
Incidentally, I am guessing the H is a Cyrillic N, and that 6H1Pi or 6N30P are equally valid. We seem to have an odd mix of transliterations in this business! Is the H or N an indicator that the tube is a dual triode? I note that there are some 6Cxx tubes (or 6S) which are single tubes - the 6C33B and the 6C45 come to mind. Does anybody know?
- Re: Music in a bottle: 6H30-Pi Tom §. 05:15:34 06/13/00
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- In Reply to: Re: Music in a bottle: 6H30-Pi posted by Paul Joppa on June 12, 2000 at 21:42:34:
> > Any sense if the 6H30Pi is equally silent when kicked? < <
When I first pulled the tube out of the box, I gave it a little tap (it wasn't plugged in to anything). What I heard sounded like the mica rattling against glass that lasted for about 4-5 seconds. There is a little wafer of what appears to be mica hanging in between the getter and the mica spacers used on the plates. I have no idea why it is there. Anyway, after plugging the tube(s) in and whacking the box with a sledgehammer or two, I feel the 6H30Pi is just as ruggedly built as the 6N1P.
Tom §.
- Re: Music in a bottle: 6H30-Pi Uncle Ned 02:04:50 06/13/00
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- In Reply to: Re: Music in a bottle: 6H30-Pi posted by Paul Joppa on June 12, 2000 at 21:42:34:
C, single triode, H, dual triode.
You can look it up here:http://www.arrakis.es/~igapop/russianotes.htm
C is also a *suffix* used to designate a glass tube.
- Re: Music in a bottle: 6H30-Pi Tom §. 05:15:34 06/13/00
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- Re: Music in a bottle: 6H30-Pi bill 13:15:22 06/12/00
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- In Reply to: Music in a bottle: 6H30-Pi posted by Tom §. on June 12, 2000 at 08:30:27:
Tom,
Thanks for reporting your results using this new tube type (at least newly available). Pardon my ignorance, but do I have this right? You're taking the signal right off of the plate and going straight to the output jack via a coupling cap (without a buffer of some sort)? Also, a few weeks ago when this tube was being discussed there was concern over possible oscillation problems. Did you notice any and/or did you do anything special to avoid such a problem? Thanks again.
Bill
- Re: Music in a bottle: 6H30-Pi dave slagle 14:51:28 06/13/00
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- In Reply to: Re: Music in a bottle: 6H30-Pi posted by bill on June 12, 2000 at 13:15:22:
look at the final stage of the loesch preamp... otherwise known as the loesh linestage...
this was depending on use a paralelled dj8 or 1/2 a 5687 loaded with a 10K plate load resistor, 2.2 ufd cap to a 10-15K attenuator....
there are 10-100 ohm resistors on each pin of the tube to prevent oscillations, and this tried and true design works like a champ...
the 6H30 looks like a prime candidate for this situation... run some current and use a 3-4K plate load resistor... a 10K output attenuator will do just fine...
careful consideration to the PS and proper matching to the following amp will make this thing slay anything commercial out there for a fraction the cost.
the schematic is on the net somewhere... don't recall where... you'll have to dig for it.
dave
- Re: Music in a bottle: 6H30-Pi Tom §. 13:25:53 06/12/00
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- In Reply to: Re: Music in a bottle: 6H30-Pi posted by bill on June 12, 2000 at 13:15:22:
Yeah, my input impedance for the amp I use is around 80K @ 30Khz. I'd say the output impedance for the preamp is around 1K. Certainly higher than the "standard" 600ohms but quite adequate for coupling to my amp. So yes, I just use a coupling cap to the output (1uF Solen/Angela fast cap). In that discussion about oscillation, I mentioned that I was already using a grid resistor. My plate resistance is 6K and my grid resistor is 6.2K. I haven't tried shorting out the grid resistor to check for oscillations yet.
Tom §.
- Re: Music in a bottle: 6H30-Pi dave slagle 14:51:28 06/13/00
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- Re: Music in a bottle: 6H30-Pi RD 12:02:00 06/12/00
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- In Reply to: Music in a bottle: 6H30-Pi posted by Tom §. on June 12, 2000 at 08:30:27:
Thanks for your excellent report. I did not believe that the 6H30-Pi was available on the US market. I called Triode electronics and ordered a couple to try out in my parafeed line amp.
- Re: Music in a bottle: 6H30-Pi DrM 13:33:48 06/12/00
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- In Reply to: Re: Music in a bottle: 6H30-Pi posted by RD on June 12, 2000 at 12:02:00:
Howdy,
Victor says this has a plate resistance of 200 ohms, but Steve Bench's data runs more around 2500 ohms. Can anybody explain the difference? This is really in intriging tube.-D
- Re: Music in a bottle: 6H30-Pi Tom §. 13:55:29 06/12/00
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- In Reply to: Re: Music in a bottle: 6H30-Pi posted by DrM on June 12, 2000 at 13:33:48:
> > plate resistance of 200 ohms < <
That's the output impedance when he has umpteen 6H30's in parallel like he does with his design.
> > but Steve Bench's data runs more around 2500 ohms < <
The plate resitance will be different depending on the op point. As you can see from Bench's data (which was quite helpful) the plate resistance varies from 1200 to 2500 ohms. That's why that parameter is usually called dynamic plate resistance. :~)
Tom §.
- Re: Music in a bottle: 6H30-Pi Tom §. 13:55:29 06/12/00
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- Re: Music in a bottle: 6H30-Pi DrM 13:33:48 06/12/00
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