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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets. |
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14th Jun 2008, 6:19 pm | #1 |
Nonode
Join Date: Dec 2002
Location: Coulsdon, Surrey, UK.
Posts: 2,135
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Re: se el34 amp
Probably about 3-4 watts - It's nothing special ( no feedback ! ) Andy
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15th Jun 2008, 8:36 pm | #2 |
Nonode
Join Date: Mar 2005
Location: Nuneaton, Warwickshire, UK.
Posts: 2,039
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Re: se el34 amp
Hi,
If it's an EL84, not a EL34, then two of them would require about 100mA from the HT supply and then a couple of amps from the 6.3v heater supply. Cheers Aub |
16th Jun 2008, 11:57 am | #3 |
Retired Dormant Member
Join Date: Nov 2007
Location: Hifa Israel
Posts: 146
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Re: se el34 amp
Hi,100k for ef 86 cathode-isnt that much to high?
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16th Jun 2008, 4:00 pm | #4 |
Retired Dormant Member
Join Date: Mar 2003
Location: Birmingham, West Midlands, UK.
Posts: 785
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Re: se el34 amp
Yes, if it is 100k - it is difficult to tell from the image. I'd reckon 2.2k or 3.3k would be adequate for a triode connected EF86, but I don't think this circuit is particularly special anyway. By using the EF86 is pentode mode you'd get more gain to enable some negative feedback to improve response.
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16th Jun 2008, 5:29 pm | #5 |
Dekatron
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 16,536
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Re: se el34 amp
Or you could use the same valves in the amplifier circuit of the Mullard 3-3 which would probably give better results and is interesting too!
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16th Jun 2008, 7:09 pm | #6 |
Rest in Peace
Join Date: Mar 2006
Location: N.W. Oxfordshire(Chipping Norton)
Posts: 7,306
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Re: se el34 amp
Looking at the schematic carefully, I'd say that the EF86 Cathode resistor is 100R, not 100K, though the former value may be too low.
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16th Jun 2008, 7:33 pm | #7 |
Retired Dormant Member
Join Date: Dec 2003
Location: North London, UK.
Posts: 6,168
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Re: se el34 amp
I'm not convinced about the design of this amp. Apart from the 100K cathode resistor the volume control is used as the grid bias resistor. This is poor practice and tends to give scatchy control with anything less than an absolutely perfect pot.
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16th Jun 2008, 9:04 pm | #8 |
Octode
Join Date: Sep 2004
Location: St. Albans, Hertfordshire, UK.
Posts: 1,478
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Re: se el34 amp
Are there any advantages in running an EF86 in "triode" mode , as opposed to a proper triode (ECC83)?
I might be a traditionalist, but any circuit drawn with valves on their side ( apart from those in push-pull, of course) can't possibly work very well
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Regards, Richard, BVWS member |
17th Jun 2008, 10:18 am | #9 |
Dekatron
Join Date: May 2008
Location: Derby, UK.
Posts: 7,735
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Re: Single ended EL34 amplifier.
Am I missing something?
Instead of using a pentode in triode mode, why not use something like an ECL82 which contains both a triode and a power pentode in one package?
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If I have seen further than others, it is because I was standing on a pile of failed experiments. |
17th Jun 2008, 12:49 pm | #10 | |
Dekatron
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 16,536
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Re: se el34 amp
Quote:
Chris |
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