anyone have an opinion on these?
I'm going to get some, and cant afford to ship them both..
With 6C33C I dont need any iron.. but is 2 enough to run them into 8 ohms? also, I hear they change plate current draw after a while?
GM-70 looks cool too, but I can't afford the iron for them..
(and where the heck do i find a socket? )
I'm going to get some, and cant afford to ship them both..
With 6C33C I dont need any iron.. but is 2 enough to run them into 8 ohms? also, I hear they change plate current draw after a while?
GM-70 looks cool too, but I can't afford the iron for them..
(and where the heck do i find a socket? )
TUBES TO GO.
Hi,
You mean as an OTL amp?
Two won't be enough,you'll need at least four.
You could use two and than add the iron on the output.
This doesn't have to be of the highest quality and will give good high frequency response.
They're not the best behaving tube around so you better buy more then you need.
It is a good idea to burn these in for a day or two and they take about an half hour to stabilize.
The socket is a standard Jumbo 4.Not a problem,most valve vendors should carry these.
Cheers,
Hi,
You mean as an OTL amp?
Two won't be enough,you'll need at least four.
You could use two and than add the iron on the output.
This doesn't have to be of the highest quality and will give good high frequency response.
They're not the best behaving tube around so you better buy more then you need.
It is a good idea to burn these in for a day or two and they take about an half hour to stabilize.
The socket is a standard Jumbo 4.Not a problem,most valve vendors should carry these.
Cheers,
PIC.
Since everyone is always begging for a pic:
Since everyone is always begging for a pic:
An externally hosted image should be here but it was not working when we last tested it.
For the 6c33, if you run it hard, youll need to automatically adjust the bias constantly. It was designed as a voltage regulator.
I think you'll find the GM-70 doesn't use a Jumbo, but some wierd thing with varius diameter pins.
Most people adapt a "Septal" (6c33) socket bu drilling it. But I think the proper thing is available from 1 USA source.
Enjoy,
I think you'll find the GM-70 doesn't use a Jumbo, but some wierd thing with varius diameter pins.
Most people adapt a "Septal" (6c33) socket bu drilling it. But I think the proper thing is available from 1 USA source.
Enjoy,
Oops.
Hi,
Sorry,the pic got me fooled.
You mean this kind of job then?
Hi,
Sorry,the pic got me fooled.
You mean this kind of job then?
An externally hosted image should be here but it was not working when we last tested it.
yeah, they use that odd socket.
I found a really good price on them. (lets say the tube costs less than shipping), but shipping from europe isnt too cheap, so I'd like to keep the tube count low.
(I think 6C33C is 200g, GM-70 is ~250g)
the heater is pretty heavy on both tubes.. i can deal with that though.. not sure what to do for an OPT for a GM-70..
i'll grab some 6S19P ( roughly equivalent to 1/2 6AS7/6080 ) and maybe some 6P14P too. (EL84 with slightly jacked anode dissipation [12w vs. 14w])
Ive tried 6P14P SE ultralinear before, but the iron wasnt too hot, and i still need to add a cathode by-pass sometime..
I found a really good price on them. (lets say the tube costs less than shipping), but shipping from europe isnt too cheap, so I'd like to keep the tube count low.
(I think 6C33C is 200g, GM-70 is ~250g)
the heater is pretty heavy on both tubes.. i can deal with that though.. not sure what to do for an OPT for a GM-70..
i'll grab some 6S19P ( roughly equivalent to 1/2 6AS7/6080 ) and maybe some 6P14P too. (EL84 with slightly jacked anode dissipation [12w vs. 14w])
Ive tried 6P14P SE ultralinear before, but the iron wasnt too hot, and i still need to add a cathode by-pass sometime..
PRETTY COOL TUBE
Hi,
Power triode, audio industry, hard glass envelope for high temperature operation and massive graphite anode, very low distortion. suitable for S.E. or P.P. amplifiers.
Technical features on GM-70:
Filament - DHT
Voltage (AC or DC) - 19-21 V
Current - 2.8-3.4 A
Amplification - 5.6-8.2
Capacitance
G-F - 6.5 pF
G-P - 4 pF
Maximum rating
DC plate voltage - 1650 V
Plate dissipation - 125 W
Colt45,
Does anyone know Rp of this tube?
At first glance you're going to need iron along the lines of the 845.
Ciao,
Hi,
An externally hosted image should be here but it was not working when we last tested it.
Power triode, audio industry, hard glass envelope for high temperature operation and massive graphite anode, very low distortion. suitable for S.E. or P.P. amplifiers.
Technical features on GM-70:
Filament - DHT
Voltage (AC or DC) - 19-21 V
Current - 2.8-3.4 A
Amplification - 5.6-8.2
Capacitance
G-F - 6.5 pF
G-P - 4 pF
Maximum rating
DC plate voltage - 1650 V
Plate dissipation - 125 W
Colt45,
Does anyone know Rp of this tube?
At first glance you're going to need iron along the lines of the 845.
Ciao,
I found a russian datasheet, but can't find anything for Rp.
says
resistance of <word i dont understand> = more than 20 Mohm (with a value like that they must mean pin to pin resistance or something.. no idea..)
ok.
----GM-70-----
Vf = 20±1v @ 3±0.3amps
mass = 280g at most
life = minimum 1000hrs.
------nominal ratings-----
Va = 15,000v
Ik = 800ma++ (at 180v plate and grid) -- huh?. i guess my russian is pretty bad.
Gm = 6ma/v (at Va = 600v, Ia = 160 and 260ma) -- and = or maybe? hmm.
µ = 6.7 (Va = 1.2 and 1.0kV, Ia = 125ma) -- again, huh?
---max---
Va = 1,5kV
Pa = 125w (150w for under 1 minute). (minute = minuty hehe)
reverse grid current = 40 µA
http://cityradio.narod.ru/spr/tubes/russian/detail/gm-70_2.html
(cityradio, so its slow..)
says
resistance of <word i dont understand> = more than 20 Mohm (with a value like that they must mean pin to pin resistance or something.. no idea..)
ok.
----GM-70-----
Vf = 20±1v @ 3±0.3amps
mass = 280g at most
life = minimum 1000hrs.
------nominal ratings-----
Va = 15,000v
Ik = 800ma++ (at 180v plate and grid) -- huh?. i guess my russian is pretty bad.
Gm = 6ma/v (at Va = 600v, Ia = 160 and 260ma) -- and = or maybe? hmm.
µ = 6.7 (Va = 1.2 and 1.0kV, Ia = 125ma) -- again, huh?
---max---
Va = 1,5kV
Pa = 125w (150w for under 1 minute). (minute = minuty hehe)
reverse grid current = 40 µA
http://cityradio.narod.ru/spr/tubes/russian/detail/gm-70_2.html
(cityradio, so its slow..)
DATASHEETS
Hello,
That's the insulation resistance.
This sheet is a bit easier to read perhaps:
GM70
And someone has been there before you too:
An interesting explanation of the cyrillic codes:
RUSSIAN CODING.
Ciao,
Hello,
That's the insulation resistance.
This sheet is a bit easier to read perhaps:
GM70
And someone has been there before you too:
An externally hosted image should be here but it was not working when we last tested it.
An interesting explanation of the cyrillic codes:
RUSSIAN CODING.
Ciao,
TOO BAD
Hello,
Too bad.You would have loved the sound of these huge graphite plates!
In case you may need more data on the 6C33C:
DATA 6C33C
Ciao,
Hello,
Too bad.You would have loved the sound of these huge graphite plates!
In case you may need more data on the 6C33C:
DATA 6C33C
Ciao,
Re: PRETTY COOL TUBE
I did a bit of extrapolating, and came up with an Rp of 1100 - 1500 ohms which tallies pretty well with the 845. Of course the final Rp is dependant upon the bias point, and may in fact be higher.
Thanks for the curves too. Best I've seen for the tube.
I've thought about getting a quad of the GM70's and buildidng a PP amp from them, along very similar lines to the SE schematic posted before (the bias supply implementation stinks though - blech). However long term supply of the tubes has me a little concerned. If they're like all the other thoriated tungsten transmitter tubes, they should last for many many years. But.......
Maybe I should just buy 8.
Oh, and that heaters a killer - 60W per tube! I thought the 813 was greedy.
WRT sockets for the GM70. Why not solder to the pins?
Cheers
Frank,fdegrove said:
I did a bit of extrapolating, and came up with an Rp of 1100 - 1500 ohms which tallies pretty well with the 845. Of course the final Rp is dependant upon the bias point, and may in fact be higher.
Thanks for the curves too. Best I've seen for the tube.
I've thought about getting a quad of the GM70's and buildidng a PP amp from them, along very similar lines to the SE schematic posted before (the bias supply implementation stinks though - blech). However long term supply of the tubes has me a little concerned. If they're like all the other thoriated tungsten transmitter tubes, they should last for many many years. But.......
Maybe I should just buy 8.
Oh, and that heaters a killer - 60W per tube! I thought the 813 was greedy.
WRT sockets for the GM70. Why not solder to the pins?
Cheers
GM70
Hi Brett,
Thx for the info,Rp must be in that area.
Silly how people look for a dream amp and then neglect details like that.
And there are other things there I don't like.
Just for starters,you mean?
These would solve your 845 problem though.
(Unless you are looking yo help out someone else with those.)
You could do that.
Ciao,
Hi Brett,
Thx for the info,Rp must be in that area.
Silly how people look for a dream amp and then neglect details like that.
And there are other things there I don't like.
Just for starters,you mean?
These would solve your 845 problem though.
(Unless you are looking yo help out someone else with those.)
You could do that.
Ciao,
Colt45 said:Maybe I'll have to quit smoking so i can afford more tubes..
What are cigarettes these days $7-8/pack. A pack a day habit is a couple hundred dollars a month -- $2500 a year. Now those are loone bucks so about $1600 USD. Buys a few tubes -- some iron too.
Sounds to me like you should quit -- your food will taste better too (or so i am told).
dave
Be aware that there are 2 kinds of GM-70;
one had the nice graphite plates that Frank mentions, the other has pressed metal.
Ask the supplier specifically, as the number is the same.
The iron need not be so expensive. IMO it's worth saving a little for.
BTW heater hum is an issue. The heaters are 20v.... that old chesnut....
Hi
Some time ago I though of making a power amp with the 6C33C. But the prices of the iron really scared me. For single ended operation these xformers are a bit odd (under 600 ohms on primary). I was playing with a double 6SN7 driving a single 6C33C in single ended mode. Erno Boberly has a design on that too.
The main advantadge of these tubes is the use of *only* around 200V. But current is quite high. I believe the GM-70 needs much higher voltages.
For lowest prices I believe Russia is the place to go.
Some time ago I though of making a power amp with the 6C33C. But the prices of the iron really scared me. For single ended operation these xformers are a bit odd (under 600 ohms on primary). I was playing with a double 6SN7 driving a single 6C33C in single ended mode. Erno Boberly has a design on that too.
The main advantadge of these tubes is the use of *only* around 200V. But current is quite high. I believe the GM-70 needs much higher voltages.
For lowest prices I believe Russia is the place to go.
The 6c33 also has the advantage of being indirectly heated.
Do check out the caveats regarding bias stability.
IMO The best places for samll quantity orders are:
http://tonywelch.com
and
www.kwtubes.com
Cheers,
Do check out the caveats regarding bias stability.
IMO The best places for samll quantity orders are:
http://tonywelch.com
and
www.kwtubes.com
Cheers,
DEAR JOHN...
Hi,
Allow me to correct the link to Tony Welshs' site:
http://www.tonywelsh.com
Cheers,
Hi,
Allow me to correct the link to Tony Welshs' site:
http://www.tonywelsh.com
Cheers,
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