I got my Pro Junior today (questions inside)

[appar111]

I received my Fender Pro Junior today at work (yay!). It's a standard black tolex version, with stock tubes (Sovtek EL84's and fender labelled Groove Tubes), and the stock brown ceramic speaker. In excellent condition for $230:

http://cgi.ebay.com/ws/eBayISAPI.dll...5879&rd=1&rd=1

Couldn't wait to get it home tonight to try it out with my teles. I'd been looking for a small amp for cookouts, jamming w/ friends, etc. and had the Vox Pathfinder 10 for a couple days until I stumbled upon this Pro Jr. on ebay.

The sound is how I remember it from trying Pro Juniors at GC a few times in the past year or so--- clean from 1-4 on the dial, while still somehow sounding abrasive on the ears, harsh sounding at volumes 4-6 and good overdrive tone from 6-9. From 9 on up, dirt city!

To be fair, I knew this when I got it. It's just a little "ehh" when you hear it again. A little disheartening.

So here are my list of mods for this little sucker:

1. negative feedback loop mod - clipping the purple wire from the speaker out to the circuit board. I've read that this is supposed to make the amp sound less stiff and more tweedy.

2. new tubes - somethin' tells me the Sovteks are just not doing this thing justice. I'll either do TAD EL84's or RCA 6BQ5's for power tubes, and Jan-Philips 5751's or a combination of a Tung-Sol in V1 and an EH 12AX7 in V2 for the preamp tubes.

3. new speaker - a Weber Vintage Series alnico 10A125-O 30-watter

4. clear silicon caulking around the inside joints of the cabinet and around the power and preamp tubes where they plug into the sockets (had a Real Tube pedal that had this). I'll wait until I've decided on tubes before I do this obviously.

5. JMR tube dampers for the power & preamp tubes

6. removing the top center screw on the back panel to reduce hum

My question is, how much will all these mods improve the sound & performance of this amp? Most everyone puts new tubes in, so that's no biggie, and alot of players tend to replace the speaker, so that's not uncommon either. I like modding stuff, so it's fun, but every so often the process gets frustrating and I feel like I'm chasing my tail, and I'm hoping this isn't one of those cases....

Advice, opinions?

[Wally]

Congrats on the amp, and luck on the mods. I would suggest doing things one at a time. If you are positively decided about changing the speaker, do this first. there will be a big change from the stock to that Alnico WEber....the harshness of distortion will smooth out. Bottom end may even get bigger. Sometimes, Fender chooses speakers on the basis of economics rather than sonics. Proceed from there.
I am not high on silicone treatments on tube sockets...not sure what that is about. Silicon on the joints...if a joint is loose, I would do a glue job. IF the joints are not loose, there should not be a problem there and the silicon is just an indicator to a future buyer that the cab has rattles.
If the amp is not humming, then the screw is not a problem. I would leave it there to decrease cab rattles. I have heard of some folks shortening the screw to avoid the grounding contact that causes the hum in some of these amps.
Negative feedback loops are there to clean up the amp's sonics. Removal or adjustment of the resistance will enrich the tone, imo....but if you are wanting more headroom don't do it.
Tube changes may or may not get you where you want to go...but we all do it, right? You gotta do the search. Let us know what transpires.

[appar111]

Wally-
Thanks for the response. As far as silicon around the tubes after they are in their sockets, I've found it a little better way of securing the tube and avoiding a rattly tube retainer.

Removing the negative feedback loop and enriching the tone is what I'm after--- I want a full, round, warm, slightly overdriven tone at lower volumes, so I think this mod would be just what the doctor ordered. Some say it's the single most sonically distinguishable mod you can do on the amp. It would definitely put it more in the tweed camp.

I'll most likely get a speaker first. Although I did win an auction last night for a NOS GE 12AX7 to put in V1, so I'm off to a good start.

I'm looking at the Weber Signature Series "Alnico Signature 10". It's less than half the cost of the Vintage Series "10A125-O" ($40 versus $95), so I could save a huge chunk right there if it's a decent speaker.

Also, if I go w/ JJ's for the power tubes instead of NOS EL84/6BQ5's, that would save another chunk ($17 for a set versus $50).

I already got the V1 tube, so it should be no problem to find a decent 12AX7 for the phase inverter (Tung-Sol for $15 or a Svetlana for $10).

So if I'm a little more frugal in my choices, I could save myself about $90-95 when modding this over what I was originally planning to spend.

My total investment would be $340 ($250 for the amp w/ shipping, plus $90 in mods)-- that's the cost of a new Pro Junior in the store. Or I could go whole hog and my total investment would be about $435.

[Mickey]

Originally Posted by appar111

6. removing the top center screw on the back panel to reduce hum

This is for a very specific, and VERY audible hum. It's not even a hum, it's more like a buzz, a fog horn. Either you have the noise or you don't. if you don't, no need to do this one. If you do, you can just back the screw off a little.

Other than that, i've been wondering about this mod for other general noise.

http://home.comcast.net/~machrone/bjr/bjrhum.htm

Seems pretty simple, if it works. Doesn't look like you even need to solder anything, just screw down a piece of metal under an existing screw. But I know nothing about amp tech, zero.

[TexGoneNW]

Wally pretty much nailed it.

There are cheaper alternatives to the Weber speaker. I like the old blue-frame Fender branded Alnicos.

Any ol' good 12AX7 should be okay in the phase inverter.

Suggest speaker first and then lower gain preamp tube to settle down the grind that's normally dialed in on the stock PJ's. I use JAN GE 5751.

I simply removed the power tube springs and haven't had a problem.

[slideman]

I actually prefer the same Weber, but in the 20-watt rating. It breaks up really nicely and early -- but that's what I wanted. The other speaker recommendations are very good as well.

Also, not sure if it was a coincidence or not, but after my speaker swap, the notorious PJ hum was gone. Go figure.

[zook]

Don't rule out the Eminence Legend 105. It's a great bargain and is much better than you would expect.

Winnie

[appar111]

Originally Posted by TexGoneNW

There are cheaper alternatives to the Weber speaker. I like the old blue-frame Fender branded Alnicos.

Any ol' good 12AX7 should be okay in the phase inverter.

Suggest speaker first and then lower gain preamp tube to settle down the grind that's normally dialed in on the stock PJ's. I use JAN GE 5751.

I ended up getting some preamp and power tubes on Ebay last night. A NOS GE 5751 ($18) for V1:

http://cgi.ebay.com/ws/eBayISAPI.dll...4573&rd=1&rd=1

...and a NOS GE 12AX7 ($20) for V2:

http://cgi.ebay.com/ws/eBayISAPI.dll...9767&rd=1&rd=1

For power tubes I got some NOS RCA 6BQ5's ($50 for the pair) that tested at well over 100%:

http://cgi.ebay.com/ws/eBayISAPI.dll...6018&rd=1&rd=1

American glass all the way in this puppy!

For a speaker, I think I may go with a Weber alnico Sig10 for early breakup and a warm, woody, tweedy sound. Plus it's $40 versus $95 for a Weber Vintage Series 10A125-O. That difference in price alone paid for the RCA's.

I'll do the negative feedback mod last (if at all), since the speaker & tube swap should change the sound significantly (it should, right?)

[appar111]

Just scored a NOS Westinghouse-branded RCA 5751 w/ blackplates for $35. A little pricey, but I've seen them listed for more on a few vintage tube sites, so I don't feel too bad.

Considering I sold a pair of studio headphones and a Boss DD-3 that paid for 9/10 of the cost of the Pro Jr. itself, and I'm using my mileage check from work (and some b-day $ to pay for the Weber speaker), my total out of pocket for this small amp project is only $125.

Not bad, ehh?

[duojet]

Appar111:

The single most important"must" for the Pro Jr.,is to use an EQ.with it.You will be amazed how this amp comes alive and opens up with just a little freq.adjustment.I wont even play my PJ without it.Absolutely takes the heavey,sodden,wool blanket off of the amp.A Jensen P10R takes it a step further,too,but nothing is as dramatic as the EQ.I just use a modded GE7 Boss pedal.Stock,these pedals are too noisy(more hiss is not what you want with a PJ!)

[tjalla]

Originally Posted by appar111

Removing the negative feedback loop and enriching the tone is what I'm after--- I want a full, round, warm, slightly overdriven tone at lower volumes, so I think this mod would be just what the doctor ordered. Some say it's the single most sonically distinguishable mod you can do on the amp. It would definitely put it more in the tweed camp.

I'm one in this camp for sure, and I'd do it 1st (its free and reversible, anyway - just unsolder that wire, rather than clip). Once i removed the NFB, the amp had the right 'feel', OD characteristic and warmth that I was after. I *then* chose the speaker based on the tone/attack/eq response I was after... for me the 10A125 works great. The Weber with the 'O' cone may be on the darker side - note that's one side effect of the NFB mod, the amp gets less "stiff/glassy" and more "loose/brown".

I'll also 2nd the EQ pedal option - I've run my SIB Fatdrive (basically a tube pre with EQ, no overdrive at all), and it does open up the amp another notch.