Blues junior: differences between all versions?

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ElPositivo

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I’m in the market for a second hand blues junior. I need something of that size to use on gigs too small for my bigger amps, but too big for a champ. I played one a couple times and really had fun with it. I might leave it stock or rip all electronics out and make my own handwired circuit in it as a fun project for later this year.

There is a ton of information on these amps but nowhere do I find a clear comparison to the technical differences between all the versions. What circuit changes are there from one version to another? I’m also curious which models come with what speaker. Hope someone can help me out or lead me to a website that lists all this info in one spot.

Thanks!
 

68goldtop

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Hi!
I’m in the market for a second hand blues junior...

There is a ton of information on these amps but nowhere do I find a clear comparison to the technical differences between all the versions...
To make it brief ;)
The versions III and IV are good to go right from the start.
Easy to tell by the black control-panels.

Versions I and II both had their (different) shortcomings, which, I think, have been addressed in V III and IV.

cheers - 68.
 

bobbythegoose

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I would suggest to get a BJ IV with a Cannabis Rex speaker. Many issues with the older Blues Juniors were addressed in the IV. The reverb is far better in the IV, and the "ice picky" sound is very much tamed especially with a Can Rex speaker. I have the Sweetwater Edition Blues Junior IV in Western Tolex. This comes stock with a Can Rex. I love it so much.

That said, here are some comparisons between III and IV:

 

Carcinogen

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I worked in the shipping department of a Sam Ash for a couple years and I know around 2012-13 they started releasing different colored tolex models that all had different speakers in them, I think they did the same with the Excelsiors, too.
 

Phrygian77

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There really isn't that much difference circuitwise in the IV, mainly a coupling cap change that increases the low end slightly, the signal for the reverb is taken earlier in the circuit (pre-tonestack), and the output is now cathode bias. The biggest limiting issue is still the size of the cab. IMO, all they did was make it more pedal friendly and more appealing to bedroom players.
 
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ElPositivo

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Thanks for the replies. I’m coming to learn the differences aren’t as big as I imagined. I got my eyes on a III at the moment that I can get for a good price. I found that the IV only has two component changed so I can mod it to a IV easily.
 

PI Mullard

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I own a few amps including a Blues Jr III that is my grab and go amp for rehearsals. I play humbuckers and single coils, clean and brown, Jazz, Blues, Soul, Rock.

I bought the BJ about 10 years ago (I've had many amps before it) It wasn't perfect, but I kept it because it had enough power in a small handy package. Since then I've tried several speakers, tube configurations and settings and I'm quite happy with where it's at. It sounds and feels good! (an acquired taste perhaps:) Circuit is bone stock version III.

These amps, ver I-IV incl Limited Editions, came with different stock speakers over the years and the only technical difference in a Limited Edition is the speaker and possibly the reverb tank in some case, afaik.

When comparing version II vs III there are minor changes made to the circuit, but the speaker is still the major tone shaper. I've A/B-tested ver II and III side by side in my studio, and when played through the same speaker I find the difference negligible. But the choice of speaker makes a huge difference that could explain the love/hate relation people have with this little amp.

When comparing ver III vs IV I think the ver III got more bite/edge. I haven't seen the ver IV schematics, but people claim it went from fixed to cathode bias. If that's the case, that could be considered a major circuit change that is likely to reduce headroom for better or worse. Cathode bias is less efficient and a waste of power when you want more output, but breakup can be quite sweet and smooth. Note that the gain structure, i.e your selection of preamp tubes, as well as the choice of power tubes is also going to affect the sound and feel of the amp.
 
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