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Fender Pro Junior

PostPosted: Wed Mar 16, 2011 5:49 am
by DrMojoHarp
I have a Fender Pro, Junior I've gotten back out of storage and want to put into use for a harp mike. In times past, I somehow outfitted the two preamp slots with 12AU7's to avoid feedback and figure I may have done overkill on muting the feedback potential.

I am interested in a 12AY7 after reading that AT7's wouldn't do the trick very well in the first position of the preamp slot.

On the Fender Pro Junior, would I go (1) 12AU7 and (2) 12AY7 or the other way around in the 2 preamp slots to get decent volume and warmth which I prefer to honking type blues harp?

I really do appreciate any help in this.....

Feel free to ask any questions or help clear this up for me?



Re: Fender Pro Junior

PostPosted: Wed Mar 16, 2011 10:46 pm
by MakaInOz

I make up for a lack of technical knowledge by using trial and error! These are preamp tubes and are therefore less finicky than power amp tubes (which might need to be biased). My technique would be to try it out one way (use a couple of different mics, mark where you stand in relation to the amp so you can repeat the position, write down what volume you get feedback). Then swap the tubes around (hint - wait a while for them to cool down) and repeat! Pick which configuration you like best.

I've got a Johnson T25R and finished up using one Y (first slot) and one X most of the time, but I occassionally put two Ys in. Two 'U's sucked the life out of it.

Good luck

Re: Fender Pro Junior

PostPosted: Thu Mar 17, 2011 11:05 am
by jbone1
what i got from a pro harp guy is, overdrive the front end, leave a 12ax7 in p1, and then use a 12au7- or 2 if you have a 3 tube pre amp- to tone it down. important to get the most out of the amp initially and then you have something to work with. if you cut the gain at p1 you then have to crank the amp higher and struggle to get clean tone.
this setup has worked for me on both a silvertone 1482 and my replica '59 bassman.

Re: Fender Pro Junior

PostPosted: Thu Mar 17, 2011 3:44 pm
by Cincinnati Slim
I recently bought a Blues Deville re-issue. I spent a lot of time picking brains and doing reserch to find the best way to improve the amp for harp use. What I discovered is there are very few rules of thumb, mostly due to differences in mics. A setup that sounds good with one mic might not work at all with a different mic. Speaker mixing and matching seems to be another variable. Speakers with different power ratings are said to add some crunch (I tried adding two Jensens with different ratings but wound up going back to the 4 stock Eminence setup) One thing I discovered is that most people agree that the position 1 tube (far right as you look at the amp from behind) is the first tube you want to change. This is based on what I discovered from research, and I may be completely off base here, but it certainly held true for me. I spent a week swapping between ax's, ay's, at's and au's, and without fail an ax in position 1 yielded the crappiest results.

For what it's worth, I found this page to be extremely helpful:

Good luck.

Re: Fender Pro Junior

PostPosted: Fri Mar 18, 2011 1:06 am
by jbone1
you're right slim, the tons of combinations between tubes, mics and speakers make for a lot of variables.
i use mostly either a cm powered bullet or a high z dynamic electrovoice m43u mic, occasionally a shure mc151 crystal mic. my results sound good to my ears tube wise. can't recall exactly what speakers the bassman is running but they are a good mixup fo low and high end breakup. the silvertone has a later model jensen ceramic.
actual brand of tubes and whether they are vintage make a difference as well.

Re: Fender Pro Junior

PostPosted: Sat Mar 19, 2011 2:52 am
by bottleneck
at gig volume mine sounds best with the regular old 12ax7's.

Re: Fender Pro Junior

PostPosted: Sat Mar 19, 2011 6:35 am
by Cincinnati Slim
bottleneck wrote:at gig volume mine sounds best with the regular old 12ax7's.

Once again, I think it depends on the combination of mic, amp, and speakers, and even tube brand. With 3 ax's I couldn't get close to gig volume. I have had luck with using an ay in position 1, and ax in position 2, and an au in position 3, but that's just me.

Re: Fender Pro Junior

PostPosted: Sun Mar 20, 2011 2:21 am
by bottleneck
kind of a shame too,because i have more 12 a(whatever)7's than should be possible.i was given a huge box of nos tubes.