The Pro Jr.

[A.David.MacKinnon]

The "bottom of the snare" thread inflamed my gear lust and after playing a back line pro jr at a gig yesterday I went out and got my own today.

Some questions for all you Pro Jr people -
What changed in the different models? Mine is a 3. I believe the new ones are 4.

There was some talk in the other thread about mods. What have you guys done and why? Is there anything quick and easy that makes a big difference? Tube swapping, speaker swapping etc.

I will kick this off by saying that I like what it does as is but I'm curious. I'll be using this in my ambient band. I generally play pretty clean and need something that can handle guitar, some synth, some vocals (through pedals) and tape loops.

[Nick Sevilla]

I'm a big fan of leaving things alone. That said, questions:

What is it that you don't like about the Pro Jr., that cannot be sorted out by another amplifier you already own?

Is there something definitely missing from it's sound? And can you definitely make that aspect better by modding?

I have a good friend, an excellent guitar player, who modded one of his favorite amps, "because he could." He has regretted it ever since, and no matter what he does to try to bring it back to normal, it just keeps sucking more and more.

At some point I think he just got another stock amp, it was a Deluxe Reverb.

[vvv]

mods I think improved the Pro,Jr. (and I mentioned in the other thread) and how:

a 12AU7 in first position cleaned it up allowing louder volume with minimal breakup until fully Spinal Tap'd

a better speaker, same thing (I use the amp as a pedal platform) - those two changes were pretty significant

mine is a fairly early (early 80's, tweed) one, but I know I had a mounting screw that was 1/8 to 1/4" too long and I hadda swap it it out - I think it was pushing on the wiring

I also hadda replace the handle what eventually snapped - there are good leather ones look like the original are avail at like US$10

I also put those rubber non-vibrate rings on the tubes, but notice no difference other than they might help break a fall if ya drop 'em when swapping 'em out

and I know I eventually got annoyed with the tube retainer spring-things, and just removed 'em completely with no issues

I will note that I had some issues, for whatever reason, with tube tines corroding; after using a emery board on 'em over the years the issue seems to be resolved, altho' I still do that before recording it

it really sounds rhythm-sweet with weaker gain single coils and goldfoils - it's possible to get some nice chime that way

it sounds way cool with humbuckers into a (or stacked) cranked dirt pedals for lead - sometimes I look over to see if the amp is itself moving

a loud boosting pedal seems to really increase the dynamics (especially with the 12AU7) and total volume level

after alla that, I agree with Nick's point - other than tube and speaker swaps, I seldom do anything to amps other than clean and repair them - it's a good idear on combos to tighten the screws once in a while, and remove the spiders and roaches from inside the box (I am not referring to living roaches, mind you )

[Scodiddly]

If you bought it used, make sure it's all working 100% before you change anything. Find somebody with a tube tester, test the tubes. Use an ESR meter to check that the caps are good.

Etc. Probably wouldn't cost much to have a good tech give it the once-over.

[roscoenyc]

I'm a big fan of these amps. I have 4 that are from different eras.

First thing to do is figure out what speaker is in there. Different versions shipped with different speakers.
The Jensens that a lot of them shipped with are pretty good. If you want more volume the Eminence RaGin Cajun is very efficient.

If it's used you may want a new pair of matched power tubes. JJs are pretty consistent. If you want
some really good sounding long lasting tubes the Russian Mil Spec version of the EL84 is very good. 6n14n-EP or 6n14n-EN

Remember there is a 1/4" speaker jack on the underside of the chassis. If you have any other guitar cabinets around check out tyour Pro Jr into a closed back cab, that's a pretty amazing combination.


I did a bunch of stuff to my favorite one.
Installed ceramic tube sockets and a Switchcraft jack.
Mercury Output Transformer

There are also a couple guys who make after market cabinets for them that will hold a 12" speaker. (Blues Jr sized cabinet cut for a Pro Jr chassis). MojoTone has a nice pine one that's very lightweight. The sound gets considerably bigger with a 12 and that gives you a lot of options.

The amp is so simple and direct you can really hear the difference in power tubes and speakers.
If you haven't had an EL84 amp before it's good to know that if the amp is getting used they wear out quicker than other tubes. As long as you put in a matched pair you don't have to bias them. It's a plug and play situation.

[digitaldrummer]

If you haven't had an EL84 amp before it's good to know that if the amp is getting used they wear out quicker than other tubes. As long as you put in a matched pair you don't have to bias them. It's a plug and play situation.

Maybe that's the same issue Fender had with the Blues Jr. - they had the bias too high and literally cook the power tubes (EL84) over time. My understanding is that is one of the circuit corrections they made in the IV version (for Blues Jr at least but I think there is some commonality in the two amps). There are also mods available (changing a couple resistors) to change the bias.

[roscoenyc]

If you haven't had an EL84 amp before it's good to know that if the amp is getting used they wear out quicker than other tubes. As long as you put in a matched pair you don't have to bias them. It's a plug and play situation.

Maybe that's the same issue Fender had with the Blues Jr. - they had the bias too high and literally cook the power tubes (EL84) over time. My understanding is that is one of the circuit corrections they made in the IV version (for Blues Jr at least but I think there is some commonality in the two amps). There are also mods available (changing a couple resistors) to change the bias.

The Blues Jr uses EL84s but that's where the similarity to the Pro Jr ends.
The Bias doesn't need to be changed on the Pro Jr.

[vvv]

Has anyone tried the Bassbreaker combos? I have the 007 and the 15w., liked the former so much for recording I got the latter for small jams. (They differ a bit from each other.)

I dig dirt and I feel the Bassbreakers are great for that, although they don't give as good loud clean like the Pro,Jr.

And I paid less for used than a new ProJr., and a lot of the used ones.

[A.David.MacKinnon]

Thanks for all the great info everybody. I'm mainly looking for clean headroom and decent bass response without the amp or speaker getting farty sounding in the lows. I'm going to live with it stock for now but it sounds like swapping tubes and maybe the speaker may be all that's needed (if anything). The current speaker is stock, I think it's an eminence.

[mjau]

They’re awesome little amps. Agreed with everyone on the speaker change. That’s the only thing I’ve ever done with one, and it was for a Weber that broke up a little more gradually.

There’s some interview or otherwise out there of Nels Cline extolling the Pro Jr.

Another cool amp in a similar vein is the Orange ad5. They don’t pop up as much for sale, but I’ve seen them go for similar prices as the Pro Jr. Totally different than the newer Tiny Terror stuff Orange is pushing out now.

[vvv]

Yeah, but that Tiny Terror is awesome, particularly if you put inna AU7 and use it with an open-back cab (I have a Jet 1x10" that can be open or closed that I use withit). Not a bad bass-recording option, also.

I have a few tube amps here and the guitarist in one of the bands I'm in gravitates to that Orange over Mesa, Marshall, Fender, Blackstar and Ampeg amps, or his own Fender and Peavey amps (he has a Classic 20 and it is a very nice ProJr-type, with verb and more EQ and that 5 extra watts - his is in tweed like my ProJr, they would look cool togevver onna small stage).