Good project for vintage tubes ?

[toejammer]

I've been wanting to get into building my own effect pedals for awhile, and just finally found your forum. Been sitting on a set of NEC tubes pulled from my fathers old Sony reel to reel deck. (electronics all worked, but the belts were toast) These tubes date back to the early 60's, all NEC, all from japan :

12BH7A
6CA4
6AQ5A
12AD7
6AU6A

I'm sure the 12AD7's are more suited for a tube distortion box, but I have no idea if the others are worth using in other projects. Any suggestions welcome, thanks !

[Mustachio]

The 12BH7 is a great tube! You can use it where a 12ax7 ,12au7 etc is used. I can't remember but I thought it needed more current then the ax au at variants.

The other tubes you have I'm not sure about, Ive seen the 6AU6 before but have never used one.

The BH7 is nice though!

[rutabaga bob]

The 6au6 is good for the 'Lonewolf'.  A bit of advice: if you put the time/effort into building anything with these tubes, keep your eyes open for backups, meaning RCA's, GE's, Mullards, etc.   Avoid that cheap Jap glass if you can...it's often unreliable.

[toejammer]

Thanks guys, didn't think the 12BH7A was a good substitute for 12AX7. And I'll have to go look up the Lonewolf, see if it's something I want to tackle.

Also I was thinking it might be more practical to build a tube amp out of this matched set, since I still have the chassis they came out of w/ all the components. Otherwise I'll just salvage the caps / resistors / diodes and such for something later on.

[rutabaga bob]

the 12bh7 is nice in a Valvecaster...many think it sounds better than the standard 12au7.  Larry

[Thunderthief]

The 6AQ5A (EL90) is basically a 6V6 with a B7G base instead of an octal. It was used for audio output circuits in tube televisions, larger tube radios and such during the 50's and 60's.  It has excellent potential in a single ended power amplifier stage. 

[toejammer]

Valvecaster it is, thanks for the input guys !

[PRR]

> I'm sure the 12AD7's are more suited for a tube distortion box

Why? It's a fancy 12AX7, good for many things.

But tube gear is not just tubes. If you'd kept the electronics together you'd already have a guitar amp. Buying all that other stuff now will be somewhat expensive, whereas 6AQ5 and 12BH7 are just a few bucks.

[toejammer]

> I'm sure the 12AD7's are more suited for a tube distortion box

Why? It's a fancy 12AX7, good for many things.

But tube gear is not just tubes. If you'd kept the electronics together you'd already have a guitar amp. Buying all that other stuff now will be somewhat expensive, whereas 6AQ5 and 12BH7 are just a few bucks.

I do still have the original electronics / chassis / transformers and all. Might be an interesting build.....

[PRR]

> Might be an interesting build.....

12AX7(12AD7) and a 6AQ5 is a Fender Champ, king of the 5-Watters.

The tapedeck's mike preamp may already be wired 95% same-as a guitar preamp. Main difference may be the position of the Volume control, and lack of tone-control (or tone suitable for g-preamp).

6AQ5 is, indeed, a lightweight 6V6. Staying in specs it's good for 4.5W instead of 5.7W, but at this level we are not playing the "more-more-more!" game.

Sony surely used a decent OT. And the PT is obviously ample (especially if you only run one power-output stage and don't engage the tape-bias oscillator).

It's mostly about the switching. A tapedeck generally would not feed Mike to Speaker (acoustic feedback). It does mike to tape "Rec" and tape to speaker "Play". So sort-out the Rec/Play switch.