Dirty-South Blues Harp forum: wail on! > Getting the Blues Jr. to work for harp...
Getting the Blues Jr. to work for harp...
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Georgia Blues
1 post
Oct 21, 2012
12:27 PM
Maybe my experience will be useful to someone. I recently got a really good deal on a 2007 Blues Jr. so I couldn't pass it up. My old solid state amp had failed and I needed an economical tube amp... and there it was. I play slightly overdriven Chicago style blues through a Shure brown bullet with a 1970's 99S556 element. I've had this mic for years and love it.

The BJ was useless as purchased. A total feedback monster with shrieking overtones, weird harmonics, jumpy and irregular response, crappy tone. A mess. After reading all I could I decided to experiment with tubes and the results have been really satisfying. Here's my tube line up at present:

Mullard EL 84 RI power tubes.
V3: NOS 12DW7
V2: JJ 12AU7
V!: JJ 12AX7

I also swapped out the thin sounding stock reverb for a MOD unit. Another big improvement. Anyhow the amp is very much improved. Good bass, very nice tone and lots of overdrive control. Next come the billm mods..

Last Edited by on Oct 21, 2012 12:28 PM
Rick Davis
843 posts
Oct 21, 2012
3:25 PM
LOL. Your description of the stock BJr is funny but accurate.

Your mods are similar to the changes I made to my Pro Jr harp amp project, in particular the unbalanced 12DW7 phase inverter. I also like the 12AU7 in the secondary gain stage socket, which does not exist in the Pro Jr.

Did you change the speaker yet?

Mullard, Tung Sol, and Svetlana reissue tubes all come out of the same factory and are very similar. I personally prefer Tung Sol, but in the Pro Jr project the EH EL84 tubes sounded best to me.

Please post sound clips or vids when you can.

-Rick Davis
The Blues Harp Amps Blog
182 posts
Oct 21, 2012
4:48 PM
GB what tube do you think helped most?

I have tried the 12DW7 and found it too harsh.

MBH member since 2009-03-24
23 posts
Oct 21, 2012
10:10 PM
With all due respect I guess I'm just not getting it. I have a new limited edition Blues Jr. III with a Celestion Vintage 30 speaker and have found it to be my favorite small amp by far. I have no feedback problems and the amp is capable of dirty Chicago tone or clean tone depending how you dial it in. I play through a delay pedal and sometimes a Lone Wolf Tone + pedal. Maybe the new Jr's are better for harp than the older models.
Rick Davis
844 posts
Oct 21, 2012
11:54 PM
2plankr, other than the speaker, how does the limited edition BJr III differ from other Blues Jrs? When I look it up it says it comes with an Eminence Cannabis Rex speaker (a very good harp speaker) but all the other changes are cosmetic.

-Rick Davis
The Blues Harp Amps Blog
Georgia Blues
2 posts
Oct 22, 2012
2:24 AM
Gmaccleod... It is really the combination that does it IMO.

Rick... Still the stock speaker. Looking for advice on that.
1256 posts
Oct 22, 2012
7:40 AM
@2plankr & Rick

By chance are you guys talking about the NOS Blues Jr?

@Georgia Blues

As Rick pointed out above, the Cannabis Rex is a damn good harp amp speaker. Probably the only other one I might recommend is a Weber Chicago Vintage. I myself like Peavey Blue Marvels for harp, but I'm a man of oddball tastes....

Hawkeye Kane
497 posts
Oct 22, 2012
8:12 AM
A number of years ago I owned 2 Blues Jr.s and thought they sounded great with harp. They did sound great, with the exception that when I played with a band that had drums I could never hear that great tone. People would come up to me and say "Turn up." I was unable to do that because the feedback threshold had already been reached. So I would say that for in your house or with a small low volume group, a Blues Jr. could work.
24 posts
Oct 22, 2012
9:06 AM
As far as I know the only difference between the various Blues Jr. III's is the speaker itself. I have not played through an older model of the BJ's but many have noted feedback problems. I can only say that with the III's I have have not had this problem and have played with band's consisting of bass, drums, guitar, keyboards and sax and had no problem cutting through in a small venue which is what the Jr. is designed for. I don't believe this is a NOS Blues Jr.

Last Edited by on Oct 22, 2012 9:08 AM
141 posts
Oct 22, 2012
7:28 PM
If you don't mind me asking, how much do you think this investment will cost between tube swaps, speaker replacement, cost of amp, time, etc.
I don't know much about amp modification, but it sounds to me that by the time this amp is ready for play(ie:"harp friendly"), it wil end up being quite an investment?!?

Last Edited by on Oct 22, 2012 7:29 PM
25 posts
Oct 22, 2012
10:04 PM
I paid $579.00 CDN and did no tube or speaker swaps or mods of any kind. Play through a delay pedal and a lone wolf tone+.
Georgia Blues
3 posts
Nov 09, 2012
6:11 AM
Buy a Blues Jr. new, then mod it, and it's not such a good deal IMHO. I got my 2007 model for $295. I have put about $60 dollars in tubes and $20 dollars in the MOD reverb tank. The billm basic mods will cost about $25. Changing out power supply and speaker should be $150 or so. Even with those the price tag comes in at about the retail price for a new un-modified BJ.
168 posts
Nov 09, 2012
8:15 AM
I put most of the billm mods on my BJr - to good effect. Besides new stage coupling caps and power supply 'stiffening' (double the filter caps), the most significant was the larger audio output transformer (larger iron core). It produced much deeper stronger bass tones. I also modded the reverb springs, which sounded like springs on an old screen door, by putting a tiny dab of hot glue on each spring, which dampened the tinny high frequencies, making the reverb more subtle.
Georgia Blues
4 posts
Nov 12, 2012
5:08 AM
I was surprised at how thin and weak the the stock reverb was on this amp. One thing you'd think Fender would get right. I'm looking forward doing to the billm mods. There is one other thing I do that helps control this amp. I plug in an old Martin VTC at the input with the tone set all the way to the bass side. I use the VTC volume control in combination with volume and master on the amp to adjust overdrive and tone. Seems pretty effective system for generating a variety of sounds. Get some very nice sax and bell tones... heavy crunching bass to tinny little honk.
3 posts
Nov 28, 2012
1:25 PM
What are the best valves to help feedback problem with Junior III?
500 posts
Nov 28, 2012
1:44 PM
I've been carrying around a Pro Jr and using it for both harp and guitar (just adjusting the tone control back and forth) sometimes at the same jam and I've been pretty happy with my sound, no problems cutting through.
Just wondering what would happen to my guitar sound if I did harp mods on the Pro Jr?

bluzlvr 4

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