PCL86 Tube Pre-Amp for guitar. Any Idea?

Rattlehead · 2010-09-30 12:32 pm

Hi guys!

I want to build a guitar preamp with one or two PCL86 valves.
I have two of them, I also have a transformer that I got from the same gramophone of wich i took the valves. I've got 2 output 5'6k transformers as well.

What can I do with all of this? I just want valve clipping.

Have a nice day.

Cassiel · 2010-09-30 1:09 pm

Rattlehead said:
Hi guys!

I just want valve clipping.

Have a nice day.

How much clipping? Crunch? Heavy distortion?

Rattlehead · 2010-09-30 1:14 pm

Couldn't it be adjustable? If not, I prefer.... well, heavy distortion.

Thanks!

Cassiel · 2010-09-30 1:38 pm

Just another question, have you heard a 5W tube amp amplifier? I'm saying this because you have the output transformers and the tubes to build a really nice sounding 4W tube amp. Then you could use a line out to drive another amp if you want to.

Rattlehead · 2010-09-30 1:40 pm

I tried some BlackHeart amps at an store, they sound great. Its just another possibility, why not.

I have some speakers from older amps lying arround my house so... yeah, why not.

Cassiel · 2010-09-30 3:18 pm

http://licho.rowerpower.org/gitara/practic2_lite.gif

Note that ecl86 is the same tube but with a 6.3 volts heater requirement. The triode section of the PCL86 is like a 1/2 12AX7.

Rattlehead · 2010-09-30 3:52 pm

This seems rigt to me. But I have one more question. When I plug the transformer into the mains, It creates some vibrations wich can be felt by touching the table, this is really annoying, is this normal?
And BTW, my transoformer gives 380Vac from 220Vac.

Rattlehead · 2010-09-30 3:54 pm

Aaah one last thing. The one you posted uses at least 3 valves, and I only have 2.

SY · 2010-09-30 4:01 pm

Rattlehead said:
Aaah one last thing. The one you posted uses at least 3 valves, and I only have 2.

Buy one more.

Cassiel · 2010-09-30 4:12 pm

Rattlehead said:
Aaah one last thing. The one you posted uses at least 3 valves, and I only have 2.

That schematic could be modified using the extra pentode section (triode connected) as a cathode follower driving the tone stack and you won't need another tube but it won't do heavy distortion.

Rattlehead · 2010-09-30 4:17 pm

Yeah, I don't want to buy more tubes. Any other idea?
And is that of the transformer normal?

BTW Are you Spanish? (Álvaro is a spanish name)

jlsem · 2010-09-30 5:14 pm

After all, 4,50€ is a lot of money.

John

Cassiel · 2010-09-30 5:48 pm

If you want heavy distortion you'll need 3 preamp stages, that means an extra triode. Look for the Champ preamp schematic if you don't want to buy another tube.

And is that of the transformer normal?

Maybe you have miswired the PT primary.
Yeah, I'm from Madrid.

Rattlehead · 2010-09-30 7:26 pm

jlsem said:
After all, 4,50€ is a lot of money.

John

No no, money is not a problem at all... And 4,50 is nothing.

The problem is that I can't buy things from the internet, I'm 16, so no paypal, no credit card, no nothing.

@Stalker: One of the wires were not removed from the transformer so I think it's well wired. It's not the first transofrmer I use.

Can't I use one of the pentodes as a preamp stage?

leadbelly · 2010-09-30 8:04 pm

Rattlehead said:
Can't I use one of the pentodes as a preamp stage?

You don't need to buy another tube. You can pursue 2 options: either build a Vox AC15 type amp, using the spare PCL86 power pentode as an input tube for one of 2 channels, or build a high gain type amp using 3 triodes in series, with 1 triode made from the PCL86 pentode strapped as a triode.

Rattlehead · 2010-09-30 8:12 pm

leadbelly said:
You don't need to buy another tube. You can pursue 2 options: either build a Vox AC15 type amp, using the spare PCL86 power pentode as an input tube for one of 2 channels, or build a high gain type amp using 3 triodes in series, with 1 triode made from the PCL86 pentode strapped as a triode.

Any idea on how to make that? I'm really a noob with valves.

leadbelly · 2010-09-30 8:19 pm

Rattlehead said:
Any idea on how to make that? I'm really a noob with valves.

It would actually look a lot like the schematic already posted, except the order would be PCL86 triode -> PCL86 triode -> PCL86 pentode-as-triode -> PCL86 pentode.

I'll have a look to see if I can find suitable curves or data to pick a good operating point for the triode strapped pentode

Rattlehead · 2010-09-30 8:23 pm

Thanks a lot.

But, isn't is what you say the same as Stalker said in the tenth post? (http://www.diyaudio.com/forums/tube...tube-pre-amp-guitar-any-idea.html#post2318751)

Cassiel · 2010-09-30 8:44 pm

No, I did say cathode follower which has no gain. He's right.

LOL, I guessed you were pretty young but 16? Take care, high voltages can kill you.

PT vibrating and even if it's unloaded too much AC volts at the secondary for those tubes ...hmm...where did you get that trafo from?

Rattlehead · 2010-09-30 8:54 pm

Don't worry, I take a lot of care when doing electronics, if you check my profile it says that I also do some other electronics so I'm used to take care of safety. Anyway I almost got blind with my most powerful lasers... accidents will happen. Wear always safety gear on!

If he's right, then awesome, I'm waiting for instructions on what I especifacally have to do. This forum is way more useful than a lot of other forum where noobs are just hated to death, like if everyone were born knowing all that they know.

And yeah, I'm just 16... hope people here don't hate me just for my age, just like in other sites.

The trafo was inside the gramophone of wich i took the valves of. It vibrates fully unloaded, that is: AC 220V Mains->Trafo
Nothing more on the setup. I read googling about it that is normal, depends on the quiality of the trafo, but... it scares the hell out me, lol.

PCL86 Tube Pre-Amp for guitar. Any Idea?

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