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Old 7th December 2012, 04:14 PM   #21
cotdt is offline cotdt  United States
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Has anyone tried the copper plate GM-70 and compared it to the cheaper graphite plate version?
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Old 7th December 2012, 04:25 PM   #22
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They are said to sound better, 3 times the price mind....
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Old 7th December 2012, 04:35 PM   #23
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Yes, that's what some people say. Yet graphite plates are technically better and more costly to produce...
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Old 7th December 2012, 04:36 PM   #24
cotdt is offline cotdt  United States
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Quote:
Originally Posted by Vincent77 View Post
Yes, that's what some people say. Yet graphite plates are technically better and more costly to produce...
Yes, in the world of 300B tubes, the graphite ones are more expensive. Then again, the cost of copper is getting quite high.
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Old 7th December 2012, 04:41 PM   #25
iko is offline iko  Canada
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Do the copper plate GM70 run red plated? AFAIC it'd be the ONLY reason I'd pay an extra 10% for them.
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Old 7th December 2012, 04:47 PM   #26
cotdt is offline cotdt  United States
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Quote:
Originally Posted by ikoflexer View Post
Do the copper plate GM70 run red plated? AFAIC it'd be the ONLY reason I'd pay an extra 10% for them.
It's not an extra 10%. It is $100 per tube versus $30 per tube for the graphite plate version (shipping cost included).

Yes the copper plates will glow a beautiful orange red. The GM70 is a very bright glowing tube, yet the filaments can be powered by a cheap 19-20V laptop charger (I've tried this with excellent results). It would be nice to use the bright blue glowing mercury vapor rectifiers such as 866A to power the GM70.

Please do not buy the copper GM70 until I do. I don't want to see any price increases to it.
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Old 7th December 2012, 04:55 PM   #27
iko is offline iko  Canada
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At that price you can have them all.
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Old 7th December 2012, 05:55 PM   #28
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Hello
These capacitors are good for these amplifier or better to use oil caps. I see most builder use oil caps (just because cheaper or they perform better ??)
SCR 51F 1500V-DC Polypropylene MKP Audio Capacitor for 211 845 GM70 813 2A3 | eBay
Also I purchased 12PC Epcos 1000uF 300VAC MKP capacitors (at Digi-key 1PC/$100) On 12PC they gave some discount..
I will post picture soon, I don't know if it worth to give a chance for those or I just sell them.
Greetings Gabor
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Old 7th December 2012, 06:11 PM   #29
nightyj is offline nightyj  Bulgaria
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Copper plate GM70 sound a lot different than the graphite version. Copper plate have upper midrange and high frequency presentation of the sound. The sound some kind misses all the cool things of the GM70 amplifiers. Graphite version sound is a lot more analog and transparent, instruments have better body and presentation. Both tubes are cool but in a very few situation you will prefer the Copper version.
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Old 7th December 2012, 08:01 PM   #30
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Quote:
Originally Posted by cotdt View Post
Has anyone tried the copper plate GM-70 and compared it to the cheaper graphite plate version?
I dont like the GM70 Copper plate:
1) They are expensive and rare, the Russian stocks seems low,
2) Last 50% less than the graphite plate,
3) Dont run in the same amp as the Graphite plate(the copper Bias is lower),
4) And had a lower bass level.
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