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EL34 or 6L6g
EL34 or 6L6g
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Old 13th February 2019, 11:39 AM   #21
santitrucco is offline santitrucco  Argentina
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Low distortion? minimun or medium

Single Ended? yes

10 Watts? 6 o 7 usable.

6L6G or EL34? both

Willing to use a higher wattage tube, or to parallel two of the above tubes to get the power with SE? could be higher wattage tube

Less than 10 Watts would be OK? yes

Push Pull with 6L6G or EL34; i prefer single ended

or with other tubes, EL84, or etc.? i dont know
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Old 13th February 2019, 12:40 PM   #22
45 is offline 45  Italy
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You can get 10W out of a good quality EL34 (truly selected for strong emission and gm). A bit less from the 6L6. I do prefer the EL34 but it's just personal preference. The difference between 8W and 10W is academic in real use......you find out on the bench and then forget about it.

I used 3.3K/8R output transformer that gave good power delivery in the 6-10R range which is typical for a well behaved loudspeaker. Max power was >10W into 6R with 3% THD. Feedback 16 dB.

Nominal output power into nominal 8R was about 9W with just 1% THD.

The EL34 worked at 300V plate voltage, 250V g2 voltage (both SS regulated) and 80 mA anode current. Distortion at 1W was about 0.2%...

To get these number with a 300B, first you need to run it HOTTER than 24W (which means useful life might be limited), need to use a REALLY good 300B and the driver will be quite more complicated because of the low gain of the 300B. In few words it WILL be a lot more expensive because it's not just the cost of the tubes.
With the EL34 in pentode mode a good 12AX7/ECC83 will be fine......for a power amp with about 1.4V rms sensitivity (for full output power). You can invest more money in a good quality output transformer with large bandwidth, good inductance and power handling....

With a good and proper speaker the amp sounds nicely. Do not trust generic comments about sound. They are meaningless, IMHO.
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Old 13th February 2019, 02:42 PM   #23
kstagger is online now kstagger  United States
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If you want to do it triode, the 6CB5A is cheap tube.

Check out this link: VinylSavor: Single Ended Amplifier Concept, Part 4

My version of that amplifier is here: http://6streetbridge.blogspot.com/20...amplifier.html

For single ended pentode - EL34, KT88, EL156, etc can be used. I built a "Universal" single-ended amplifier using fixed bias so I could try different tubes. Loop or plate-to-plate feedback would be needed to keep distortion low and provide damping. It is a different sound - subjectively speaking - faster and tighter bass.

Something like this: http://6streetbridge.blogspot.com/20...l-pentode.html
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Old 13th February 2019, 02:47 PM   #24
H713 is offline H713  United States
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Mmm... love the look of those VR tubes.
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Old 13th February 2019, 03:13 PM   #25
smbrown is offline smbrown  United States
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Hi Kstagger, thanks for the link to your blog. Nice write up!
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Old 13th February 2019, 11:51 PM   #26
multi is offline multi  Australia
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The main thing is have you got suitable speakers for Single ended or would be better to build Push pull..
6A3 which Glass Audio? THANKS
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Old 14th February 2019, 12:07 AM   #27
multi is offline multi  Australia
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811a amps are not for beginners; takes weeks to hand punch the chassis. many hours to wire point to point. |The amps I built are very quiet even on 105 Db speakers. One friend has used his for 22 years after 20 years the Russian 811A where still within specs, but my friend prefers the Chinese 5725B which hAVE SHORT LIVES.
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Old 14th February 2019, 12:24 AM   #28
Wavebourn is offline Wavebourn  United States
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EL34 or 6L6g
Originally Posted by Kay Pirinha View Post
Quite some bold statements, aren't they? I'm sure you want to substantiate them .
Best regards!
Cheap understanding of electronics demand expensive components, it is true. Like, expensive knowledge of electronics allows to get great results from cheap components, that's the forum is for. We are constantly discussing here how to get great sound quality. People who can learn, get it finally, using unexpensive parts. People who can't learn from the wisdom of people on this forum, are doomed to buy expensive tubes, transformers, capacitors, and even power cables.......
Nothing in the universe is perfect. The ideal things are the ones that are most optimal. Optimization criteria, what matters. When I hear "No Compromise Design", I want to take a sledgehammer and test how impact-proof it is.
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Old 14th February 2019, 09:23 AM   #29
6A3sUMMER is offline 6A3sUMMER  United States
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"Paralleling Tubes Effects" was the cover article in Glass Audio, Volume 12, Number 5, year 2000.
This was the last issue of Glass Audio, before 3 Ed Dell publications were combined into one magazine.
I can hardly believe we did the research starting in 1998 and ending in 2000, such a long time ago.

Then I presented the essence of the article at VSAC 2003. At VSAC 2008 I did a presentation and then a listening demo of
a parallel 300B amp and a push pull 300B amp, with the same currents in the outputs, and the 300B tubes all seeing the same load impedance. A null method was used to balance the gain precisely, and then the music was switched from PSE to PP and back again.

I have talked about this more than once on threads in diyAudio.

Last edited by 6A3sUMMER; 14th February 2019 at 09:29 AM.
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Old 14th February 2019, 09:41 AM   #30
JRZoid is offline JRZoid
Join Date: Feb 2019
Well EL34 Cleans Remind of good Solid State Cleans. Chimey stuff. The 6l6 is more "Glassy" and harmonicy.

I like the 6l6 more for distortion its definitely "honkier" too.
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