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Author Topic: hybrid mini 12au7 practice amp?  (Read 14813 times)

dan6896

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hybrid mini 12au7 practice amp?
« on: January 23, 2011, 02:55:23 AM »
One day i was looking around the internet for little practice amps with tube preamps. I saw the ruby tubey (but that has too many parts) and i also saw the tube cricket but i could not find a schematic. then i remembered seeing something about a tube boost that runs on 9v called the valve caster.(in case you dont know you can find that here: http://www.diystompboxes.com/smfforum/index.php?topic=63479.0

anyway that gave me an idea for a little practice amp like a ruby or noisy cricket. replace the fet input thing (not sure of the propper name) with a valve caster circuit running into the input of an lm386 power amp. Ill post a schem later

my question to you is do you thing this will work.

in advance thanks for the help.
 

J M Fahey

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Re: hybrid mini 12au7 practice amp?
« Reply #1 on: January 23, 2011, 08:38:22 AM »
Quote
Ill post a schem later

my question to you is do you thing this will work.

Who knows?  :)
Post the schematic !!  ;)

joecool85

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Re: hybrid mini 12au7 practice amp?
« Reply #2 on: January 23, 2011, 03:40:34 PM »
Sounds do-able to me.
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dan6896

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Re: hybrid mini 12au7 practice amp?
« Reply #3 on: January 23, 2011, 05:43:39 PM »
schematic attatched :tu:

rowdy_riemer

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Re: hybrid mini 12au7 practice amp?
« Reply #4 on: January 23, 2011, 06:40:27 PM »
I don't know if there is anything to it or not, but I've heard that 12AU7's don't sound too well with anything less than a 48V supply. I haven't tried to find out, though. I've got a 12au7, but I might save that for a firefly amp. The real magic with the ruby type amps is the way the LM386's sound when overdriven. Probably might as well stick with fets or op-amps. Of course, there is one way to find out for sure.  :)

dan6896

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Re: hybrid mini 12au7 practice amp?
« Reply #5 on: January 23, 2011, 08:25:04 PM »
im ordering the parts tommorow ill post again when its done. :tu: but i only have a 12ax7 and the 12au7 has to come from england so that might take a while.

J M Fahey

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Re: hybrid mini 12au7 practice amp?
« Reply #6 on: January 23, 2011, 11:55:23 PM »
Quote
the 12au7 has to come from england
Well, that doesn't mean too much because we don't know where *you* live.
You might be as close as Jersey and Guernsey or as far as Marambio Base in Antarctica or the middle of Gobi Desert !!! :lmao:

rowdy_riemer

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Re: hybrid mini 12au7 practice amp?
« Reply #7 on: January 24, 2011, 01:02:01 AM »
His user profile says New Zealand.

J M Fahey

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Re: hybrid mini 12au7 practice amp?
« Reply #8 on: January 24, 2011, 02:11:51 AM »
It's a small crazy world indeed !!!  :o :D ;D ;) :loco

Zipslack

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Re: hybrid mini 12au7 practice amp?
« Reply #9 on: February 28, 2011, 11:49:21 AM »
Looks like you're re-creating the Tube Cricket.  Here's a link to a discussion forum with the schematic.  I have a Valvecaster running at 12.6V that I really like...I have not tried bridging it to a 386 yet.

http://www.diystompboxes.com/smfforum/index.php?topic=66623.0

dan6896

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Re: hybrid mini 12au7 practice amp?
« Reply #10 on: March 03, 2011, 02:17:01 AM »
thanks for the info, Ive almost finished my prototype just gotta build a power supply and then it should be done. i didn't use an 386 because none of the ones i can find work properly, so i used some car amplifier chip amp kit its about 11.5 watts amp sounds pretty good with just the guitar plugged straight in to it.


darwindeathcat

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Re: hybrid mini 12au7 practice amp?
« Reply #11 on: October 06, 2011, 04:49:03 PM »
Hey, did you ever get this wired up and working? I've had it in my head to do the same sort of thing for a while now... I've got all the parts sitting around, but wanted to see if someone else had made this work (and what it sounds like!) before i give it a go...
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dan6896

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Re: hybrid mini 12au7 practice amp?
« Reply #12 on: October 11, 2011, 05:58:06 PM »
when i tried it with a 12ax7 it didn't really sound very good, so i built a fetzer valve instead and it sounds much better. You could try it with a 12au7 and see what it sounds like. 

darwindeathcat

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Re: hybrid mini 12au7 practice amp?
« Reply #13 on: October 13, 2011, 05:18:03 PM »
Thanks for the response. Yeah, the fetzer valve is a neat circuit. Easy to slap together and sounds so good! Interesting that it sounds better than a space-charged 12ax7... I do have some 12au7's sitting around, so I might give that a try one day, but I'd have to order some tube sockets, and I'm lazy!
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joecool85

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Re: hybrid mini 12au7 practice amp?
« Reply #14 on: October 14, 2011, 09:30:04 AM »
...but I'd have to order some tube sockets, and I'm lazy!

Heck, at least you're honest!
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