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Multi tubes amps what effect does each has?
Multi tubes amps what effect does each has?
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Old 14th February 2018, 05:17 AM   #11
aardvarkash10 is offline aardvarkash10  New Zealand
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ok, single-ended...

1= output 2 = driver (totem pole) 3 = voltage amplifier (2 stages)
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Old 14th February 2018, 07:18 AM   #12
raybies is offline raybies  Australia
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Cool, so would the drivers if changed have a big effect on sound or the output?

Thanks for all your help
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Old 14th February 2018, 10:31 AM   #13
DF96 is offline DF96  England
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The circuit has both local and global feedback, so changing one working valve for another will have little effect. Tube rolling is for guitar amps, and non-hi-fi audio amps with little or no feedback; hi-fi amps don't need it and don't respond to it.
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Old 14th February 2018, 11:50 AM   #14
Lingwendil is offline Lingwendil  United States
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Multi tubes amps what effect does each has?
^ good quick advice.


You can buy some NOS tubes to run in it if You like, Just to get some (maybe) longer life out of better quality valves perhaps, but don't go in expecting any huge difference.
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Old 14th February 2018, 11:57 AM   #15
kstagger is offline kstagger  United States
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NOS 12AT7s are cheap - pick up some Tung Sols or RCAs or whatever - no reason to go expensive, and see if they make a difference. It will probably be slight (if any) but at least you don't have a lot of money invested in the experiment.

I'm not a big fan of new 6SN7s - I would try out some GEs which are still inexpensive - at least they will last longer and may have lower microphonics.

300Bs are expensive - even the "bottom barrel" ones and tube rolling here would be pricey. I always used EH Golds = because, at least in the amps I built, they were rugged.

Just wanted to add that's a whole bunch of circuitry to drive a 300B. But I like pentode drivers, so what do I know
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Old 14th February 2018, 07:03 PM   #16
aardvarkash10 is offline aardvarkash10  New Zealand
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Quote:
Originally Posted by raybies View Post
Cool, so would the drivers if changed have a big effect on sound or the output?

Thanks for all your help
Its been said by better than me, but to repeat it in terms an Aussie would understand - there is enough feedback in that design, you could sling a dead dingo's kidney into a tube socket of that amp and barely notice a difference.

Cheers!
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Old 15th February 2018, 08:51 AM   #17
12E1 is offline 12E1  United Kingdom
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I'll have to try that...

Hold an a mo... No dead dingos around here... Dang!
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Old 16th February 2018, 10:45 PM   #18
raybies is offline raybies  Australia
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What do the mA/V hand written values mean? Is higher or lower better?
Click the image to open in full size.
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Old 17th February 2018, 12:08 AM   #19
Eli Duttman is offline Eli Duttman  United States
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That's a measure of transconductance. The exact value is less important than the closeness of the numbers. That pair is matched.
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Old 17th February 2018, 01:23 AM   #20
raybies is offline raybies  Australia
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Quote:
Originally Posted by Eli Duttman View Post
That pair is matched.
Thanks, so if a pair was say 74mA / 5.4mA/V and 74mA / 5.0mA/V would they still be matched?
1st number is inconsequential, while the 2nd determines the matching?
What deviation should there be to have no match?

Thanks... just 10 days in to learning about tube amps.
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