Triod lover said:I just finished my mighty little amp using GM-70 last week,am a newbie in this forum,any comment pls advice.
Really nice job there! What output xfmers did you use? What is the plate load Z? You are using ultralinear G2 connection to OPT yes?
Hi rcavictim,
The GM70 is a triode so he obviously won't be running it in UL as there is no screen grid.. I've included the data sheet as an attachment.
I'm actually thinking about getting a pair of these at some point to design and build an amplifier around.
I have heard a lot about a supposedly better sounding copper plate version of this tube. Standard plate afaik is graphite. Anyone have any thoughts on this? Triod Lover which version of GM70 do you use?
The GM70 is a triode so he obviously won't be running it in UL as there is no screen grid.. I've included the data sheet as an attachment.
I'm actually thinking about getting a pair of these at some point to design and build an amplifier around.
I have heard a lot about a supposedly better sounding copper plate version of this tube. Standard plate afaik is graphite. Anyone have any thoughts on this? Triod Lover which version of GM70 do you use?
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Very nice construction and wiring job. I like the combination of wood and metal for the chassis too.
I thought GM-70s were triodes.
Victor
PS, yup, Kevin confirmed it. If I didn't have as many tubes as I do, I'd buy a few of these too. They sure look cool.
You are using ultralinear G2 connection to OPT yes?
I thought GM-70s were triodes.
Victor
PS, yup, Kevin confirmed it. If I didn't have as many tubes as I do, I'd buy a few of these too. They sure look cool.
Hi..RCAVICTIM,KEVINKR,HOLLOWSTATE
Thank you all for the compliments,GM-70 is a very stable and tough like a tank it is a pure triode no G2,the output is the Electra-print load impedance is 5k.,the sound is very sweet and has a very good bass,the sound stage is just like watching the concert!!!,anyhow,i just burn-in for two weeks i think this tube will need another week or so to get it ready to rock n roll.One con about my amp is it so hot,especially living in Thailand that the temperature quite hot all year!!.I wish i lived in U.S.A or CANADA to get my amp as the heater as well.
Thank you all for the compliments,GM-70 is a very stable and tough like a tank it is a pure triode no G2,the output is the Electra-print load impedance is 5k.,the sound is very sweet and has a very good bass,the sound stage is just like watching the concert!!!,anyhow,i just burn-in for two weeks i think this tube will need another week or so to get it ready to rock n roll.One con about my amp is it so hot,especially living in Thailand that the temperature quite hot all year!!.I wish i lived in U.S.A or CANADA to get my amp as the heater as well.
Some parts of the USA are quite hot as well, and even where I live in the summer the temperature outdoors exceeds 32 C quite regularly, and gets to 40 C sometimes. We have no AC so I avoid using even the 300B amplifier when it is very hot, which because of its tube regulated supplies throws off quite a lot of heat.
It's cold outside now, but my basement listening room is always warm until outside is below 0 C..
Good to hear about the copper plate version, I have seen them being sold on eBay by reputable sellers (one or two I have dealt with before) so I think I will try a pair sometime soon.
How much power do you think you are getting, what is plate current and voltage for example?
It's cold outside now, but my basement listening room is always warm until outside is below 0 C..
Good to hear about the copper plate version, I have seen them being sold on eBay by reputable sellers (one or two I have dealt with before) so I think I will try a pair sometime soon.
How much power do you think you are getting, what is plate current and voltage for example?
Oops!
Sorry all. I am suffering from mentalpause. I somehow thought the GM70 was a euro version of the 813. My mistake. I`d love to pick up some GM70`s but the GM dealers over here in Canada just sell mostly unecessary garbage which the planet could live just fine without if they completely stopped today.
BTW, anyone got a single RCA 813 they can spare? I`ve been wanting to build a SE amp and I finally found my pair that were misplaced for ten full years and to my dismay one has an open filament. I`d go to my closest RCA dealer but alas the RCA dealers over here in Canada just sell mostly unecessary garbage (Thompson CSF) which the planet could live just fine without if they completely stopped today.
Sorry all. I am suffering from mentalpause. I somehow thought the GM70 was a euro version of the 813. My mistake. I`d love to pick up some GM70`s but the GM dealers over here in Canada just sell mostly unecessary garbage which the planet could live just fine without if they completely stopped today.
BTW, anyone got a single RCA 813 they can spare? I`ve been wanting to build a SE amp and I finally found my pair that were misplaced for ten full years and to my dismay one has an open filament. I`d go to my closest RCA dealer but alas the RCA dealers over here in Canada just sell mostly unecessary garbage (Thompson CSF) which the planet could live just fine without if they completely stopped today.
Hi...all
You figue right!!! the hotter the better for this lantern! ,i think the sweetest spot for ma the V.plate around 800 volt. the current approx. 110 M.A the sound just right.,for investment and sound quality i love the copper plate,but be awared of the plate dissipation is lower than the graphite.
You figue right!!! the hotter the better for this lantern! ,i think the sweetest spot for ma the V.plate around 800 volt. the current approx. 110 M.A the sound just right.,for investment and sound quality i love the copper plate,but be awared of the plate dissipation is lower than the graphite.
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