ECC82/12AU7 Line Preamp

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Looks overly complicated to me. I was thinking of something simpler that you could get up and running more easily. But it must be safe from electrical shock hazard. Sorry I don't have a reference, but I'm confident folks on this forum could suggest an adjustable regulated HT supply design.

I hate winding and this was the simplest thing I could think, If you add a pot this is adjustable too, don't worry I work with 25KV every day.

It looks like common cathode amplifier followed by cathode follower buffer - and CCS load for each one. Worth a try I'd say. But I don't like that you think it's necessary to use two different B+ supplies - unnecessary extra work. I like your choice of ECC99, a tube with a very good reputation.

You are right, I prefer SRPP.

If you want to explore the sound of the high voltage / operation point question for the common cathode amp I'm not sure you want to add the complexity of making this a two stage design. I would suggest, if you will allow me to say, you will not gain much more from simulation but need to put some wires together on a bench. Feed the output through a 'clean' high input impedance solid state amp and some speakers. The listen. Try different operating points etc.

I don't like SS but for common sense I'm building a valve pre-amp and a hybrid power amp.I will finish it someday.

I don't know if you have seen this web site, it could take weeks to read it all, but it's a source of much information: Tube CAD Journal - read about the Aikido and about the Constant Current Draw Amplifier.

I prefer SRPP.
Best regards
Johann
 
Hi Wavebourn
Good to see you around here.
I think that something so "politically correct"
Better, but not muuuuch better.:D
 

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Hi Wavebourn
Good to see you around here.
I think that something so "politically correct"
Better, but not muuuuch better.:D

Bigun already suggested you to ckick there: Tube CAD Journal ;)

By the way, I've seen very similar picture in real life, the same -80 dB of 2'nd order only, from my Pyramid amp that contained 5 tubes per channel (actually, 6 if to cound pentode-triode as 2 tubes). The picture was very similar on half power, 40W. However, on higher power higher harmonics were visible. I don't remember already which input tube I used there in that version of the amp, either 6F12P or ECF-200. I usually don't do such measurements, only if somebody is curious to see.
I mean, 6AU7 is not the best choise.
 
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Solvent won't do it- the enamel is a thermoset. You're stuck with abrasion or scraping. Sorry.

Hi Sy,
We get something in the market here that strips enamel from the wire. I bought a bottle a long time ago. It's a liquid that vaporates rather fast even when it is closed ( in a PVC bottle).
The liquid is not too thin like water. If I brush it on the enamel it starts to bubble up along with the enamel coating in a few minutes...maybe 2 to 3 minutes and I can just wipe away the enamel.
The liquid also lightly burns the skin if it makes direct contact ( feels like a physical burn of low intensity ) .
It doesn't say what it is but I'm sure it's pretty toxic and I can't identify it by it's smell. Another strange thing is that looking into the bottle it appears to have a very bubbly surface like a soap solution. It does have some hydrocarbon in it but I can't guess what. Looks more like a mixture of various (dangerous ! ) things.
I keep it VERY VERY safely ! Currently it has practically dried up and I had to dispose it. Not very sure if I want to get another bottle after I got a small burn when it fell on my hand! However it does a great job removing the enamel and I think a lot of local companies use this stuff.
It's manufacturer also appears to be a small time place.......based on it's address . But it could also be re-bottled into small bottles from bulk at that address rather than being manufactured there.
Wouldn't recommend it to most people..really looks bad !:dead:
 
Bigun already suggested you to ckick there: Tube CAD Journal ;)

While answering Bigun I went twice interrupted, so two replies, sorry.
I visit very often the Tube CAD Journal page, I also did simulations of Aikido.:D

By the way, I've seen very similar picture in real life, the same -80 dB of 2'nd order only, from my Pyramid amp that contained 5 tubes per channel (actually, 6 if to cound pentode-triode as 2 tubes). The picture was very similar on half power, 40W. However, on higher power higher harmonics were visible. I don't remember already which input tube I used there in that version of the amp, either 6F12P or ECF-200. I usually don't do such measurements, only if somebody is curious to see.
I mean, 6AU7 is not the best choise.

Wow! -80dB, even in my dreams, is that at 1W?
I don't know 6F12P neither ECF-200, I guess it's a low signal triode-pentode, but nothing else, I will investigate.
Is very difficult to obtain good valves here, also closed the import:(
Maybe 6AU7 is not the best choice, but I think that would have to prove.
Wim de Haan, among others, the praises, other people the hate.
Only by intellectual curiosity, can be see the schematic somewhere?:yummy:
 
sorry for the OT, i use lye in water to treat aluminum chassis....gives it a dull sheen....

ashok, you have name of that that i can look at...i use a local thing called Stripsol that removes paints, not tried on magnet wires though.....it is a pasty substance, and applied by brush, highly corrosive and painfull to the skin just like lacquer thinners....
 
Hi SY, I have some pH strips that I use to check acid content in my wine must. That's around 3.2 to 4.6 range I think and a few wider than that. I also have 0.2N NaoH solution and phenolphtalein that I use to check acid content by titration.
I can get any other acid/alkali indicators if required.
 
Hi SY, I have some pH strips that I use to check acid content in my wine must. That's around 3.2 to 4.6 range I think and a few wider than that. I also have 0.2N NaoH solution and phenolphtalein that I use to check acid content by titration.
I can get any other acid/alkali indicators if required.

The phenolphthalein should indicate if it's basic. No need to titrate, if a drop of the nasty stuff in some water still makes the indicator bright red, it's probably lye-based. Other possibility is peroxide.
 
Yes I'll try that. I'll pick up a bottle of the 'stuff' soon.
If peroxide can bleach skin pigments ( I'm brown ...will tell easily !) then this one may not be it as it didn't bleach my skin or leave any marks. Just felt like a burning sensation when it touched the skin until washed off with water.
I have some 10% H202 here but that's too dilute to bleach skin pigments!
 
Yes I'll try that. I'll pick up a bottle of the 'stuff' soon.
If peroxide can bleach skin pigments ( I'm brown ...will tell easily !) then this one may not be it as it didn't bleach my skin or leave any marks. Just felt like a burning sensation when it touched the skin until washed off with water.
I have some 10% H202 here but that's too dilute to bleach skin pigments!

I have an idea. Acetone must help, slowly adding more of acetone molecules in polymer making it softer, but it is looong way, you have to soak it for 1-2 days.
 
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