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6GW8/ECL86 based line amp
6GW8/ECL86 based line amp
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Old 11th September 2019, 12:43 AM   #11
PRR is online now PRR  United States
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Quote:
Originally Posted by Vintage Audio Projec View Post
....Minimum 24dbu in 600ohm
....Galvanic Isolation is nice with tube circuits.....
+24dBu IN 600r is just +24dBm.

Historically, if a studio needed more than the +18dB possible from a 6J7, they moved to push-pull 6F6/6V6. Partly because they could afford it. Also because if one side of a hot-worked pair failed, signal would still get through. But also because a push-pull core is much smaller than SE, and the THD is very much less.

The way you have taken NFB there is no galvanic isolation.

Do you actually have 600r loads?
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Old 11th September 2019, 02:00 AM   #12
pblix is offline pblix  United States
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Quote:
Originally Posted by Vintage Audio Projec View Post
I'm open for al options on different tubes
It's nice to do something different.
On the other hand the ECL86 is in production so I could always find an ecl86.
And you are right the price 10 years ago was a lot less then now....
Really? Where?

Quote:
Originally Posted by Vintage Audio Projec View Post
The thing is I would like to have a small sigal triode and an output pentode (or triode) in one glass envelope
This line stage will be used in different ("modular") ways so having only one tube is nice.
6FM7 is dissimilar triode in one bottle. There are others too.
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Old 11th September 2019, 03:42 AM   #13
gingertube is offline gingertube  Australia
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ECL86/6GW8 are NOT in current production - very popular tube because they were truly excellent - becoming rocking horse poo availability. Tube manufacturers - we want ECL86s brought back. ECL85/6GV8 are not in current production either but there are a heap of NOS about. Very popular in tube TVs for frame oscillator (Triode) and scan coil power drive (Pentode) Will eventually become rare.

Some Guitar Amp Guys are using them for small power amps because they could no longer rely on getting ECL86. ECL84/6DX8 are in current production and are good quality, being used for small HiFi and Guitar amps. ECL82/6BM8 are in current production too. Another good quality tube, again being used for small Guitar and HiFi Amps.. There certainly used to be an ECL80 but haven't seen one for years. Don't know if ECL81 or ECL83 ever existed. Go for ECL84 or ECL82 would be my recommendation.

Cheers,
Ian
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Old 11th September 2019, 03:43 AM   #14
kodabmx is offline kodabmx  Canada
Spreading triode love.
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6GW8/ECL86 based line amp
If you go with ECL82, I've found these these 6F3P tubes are excellent and don't break the bank.
6F3P / 6BM8 / ECL82 tube - - Tubes-Store.com
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Old 11th September 2019, 08:03 AM   #15
Vintage Audio Projec is offline Vintage Audio Projec
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Quote:
Originally Posted by PRR View Post
+24dBu IN 600r is just +24dBm.

Historically, if a studio needed more than the +18dB possible from a 6J7, they moved to push-pull 6F6/6V6. Partly because they could afford it. Also because if one side of a hot-worked pair failed, signal would still get through. But also because a push-pull core is much smaller than SE, and the THD is very much less.

The way you have taken NFB there is no galvanic isolation.

Do you actually have 600r loads?
I repaired a gates sta-level ones and they used a pushpull 6v6. Very beefy output you could say.

I do like the simplicity of SE. The neve 1073 output is also SE with standing DC trough the primary and it doesn't sound bad you could say. Ok it's with transistors but the principle (se) is the same.

As the feedback. I could take feedback from the plate (primary). Then the transformer is not in the feedback loop. If it turns out that the transformers gives problems when in the feedback loop (= ringing/oscillation) then I could do this. I liked the idea of the transformer in the feedback loop as it lowers output impedance and extends the frequency response.

For having 600ohm loads. When you make a passive mixing bus and start adding subgroup busses the loading impedance goes down. If you use higher resistance mixing resistors the noise goes up. I mainly use neve outputs and they just drive like everything.... So I wanted a tube circuit that can do the same is SE and drive like everything

Some older gear we have is 600ohm also and some of the "cheaper" whimpy preamps just don't cut it. If I remember correctly, the original 1176 (especially the revision A "blue-stripe") has a low impedance input.

Ok so I will checkout some more tubes. I like the dissimilar triodes. Didn't know they existed.
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Old 11th September 2019, 12:32 PM   #16
Steve Morley is offline Steve Morley  Canada
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Default Koda have you found....

tubes-store.com reliable? Tubes they sell test decent, not all over the place?

TIA, Steve
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Old 11th September 2019, 01:21 PM   #17
kodabmx is offline kodabmx  Canada
Spreading triode love.
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6GW8/ECL86 based line amp
Never bought from them, but I've bought the tubes through others on eBay. I don't see why they wouldn't be reliable though.
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Old 11th September 2019, 01:33 PM   #18
Kay Pirinha is offline Kay Pirinha  Germany
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Quote:
Originally Posted by gingertube View Post
There certainly used to be an ECL80 but haven't seen one for years. Don't know if ECL81 or ECL83 ever existed. Go
HI Ian,
all of these three valves existed. They have in common their common cathodes, which severely resticts their usability. As the ECL80 has a 6.3V/0.3 A heater, there was no need for an extra series heated version. Series heated versions of both the other tubes existed, though: PCL81 and UCL81 were identical to ECL81, besides the heaters, of course. But be careful with that damned Mullard ECL/PCL83 - same pentode, but very dissimilar triodes (high in the E, low to medium in the P Version)!

Btw, which manufacturer still does ECL84's/6BX8's? This is a rather interesting tube, as it looks like and behaves like an ECF80 on steroids.

Best regards!
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Last edited by Kay Pirinha; 11th September 2019 at 01:39 PM.
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Old 11th September 2019, 02:20 PM   #19
Ketje is offline Ketje  Belgium
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The ECL80 and ECL84 are very different.
The only interesting about the 80 is the Vap of 1200V, the 84 is for video-out with very high condutance.
It can be used here for line driver, an idea.
Mona
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