Opinions of Bill M mods for Blues Jr?

[Groover]

I have a "green board" Blues Junior. It sounds pretty good and is a useful tool, but I wouldn't describe the sound as amazing. That said, I am not sure I would describe any of my many (mostly Fender) amps as sounding "amazing".

But 1) I am not a "cork sniffer" and 2) I don't usually think the equipment is the weakest link in the chain.

All that notwithstanding, I am curious about the Bill M mods for the Blues Jr. and wondering what people's experience and informed opinions about them are.

[Mike62Jazz]

I have a cream board, but everything I've gotten from Bill has been a major improvement. I have done basic mods, power stiffening, adj bias, tone cap mods, Mid jumper, clean boost/presence , audio master & reverb pots. The only thing left is Power transformer swap.

[Bruce / Mission Amps]

I have one in for repair right now that has all those mods plus the little FET amp.... it might sound better then a "dead stock" one but, sorry, even with it working right, using the stock speaker, I think it still sounds cheap, fizzy and slightly trashy.

[Mike62Jazz]

I have one in for repair right now that has all those mods plus the little FET amp.... it might sound better then a "dead stock" one but, sorry, even with it working right, using the stock speaker, I think it still sounds cheap, fizzy and slightly trashy.

I also have an Eminence Cannabis Rex in mine. BTW Bruce, this is Mike from Gypsum

[Groover]

... it might sound better then a "dead stock" one ...

So do you think it's an improvement or not? I don't mind my stock one, does the job, just nothing special. And I like those speakers. (could be a case of ignorance is bliss?)

[Bruce / Mission Amps]

Hi Mike.. I know you saw the amp here.

I'm really not very impressed with it but I guess I have to concede that it is better the a stock one.
It still has some power supply hum even with the new power tubes that are idling at 9 watts each.

I've been messing with it for a couple hours and I've changed a couple caps on the board to get rid of some artifacts this one has.
But I've also discovered a nasty 12Khz- 16Khz oscillation that the push pull pot switch wiring, with respect to the NFB, ribbon cables and OT primary leads has created.
This is some of the fizz I've been hearing.
I've been moving all these wires around and can make it worse or a little better but I haven't found the combination yet that rids it 100%.
I rewired the NFB wire to go around the filter caps and that helped a very little bit but the oscillation is still there at medium loud levels.

It is the cream colored board and the FET amp is built on cheap crap Radio Shack perf board.
I'm not entirely sure what the mod is DPDT supposed to do either.
I don't have any paper work and the side of the DPDT switch it is connecting a ground to one of the lugs on the foot pedal switching stereo, pedal jack.
Since the original jack isn't switching stereo jack, I assume this is so you can foot pedal the amp or boost or both?
One of the sloppy solder joints on the dual power supply caps has come loose and the stock E-cap has a bad solder joint on the other side creating a horrible blapping noise at most low frequencies.
The master volume pot is bad and is crunching when rotating.
The second preamp tube socket is bad and the amp shuts off every once in a while.. etc, etc, etc.
These amps are just clock radio PCB junk and modding the hell out of them seems dubious to me.
What's kind of funny is the owner of this one tries to gig with it once or twice a week and he's complaining that it seems to break down frequently.

[Sweetfinger]

Don't send a boy's amp in to do a man's amp's job!

By the time you've modded this into something else, you still have a cheaply made circuit board amp that won't take much road abuse. Just take the money you were going to spend on the amp and mods, pool it, and get something reliable that already sounds great.

I'm all for a little mod here and there, but when you're buying an amp with the intention of replacing the transformers, tubes, speaker, and some/most/all of the circuit components, maybe you should just spring for a kit amp because all you're buying at that point is a cabinet and chassis.

[Gibsonman63]

I agree with Sweetfinger. I got a Blues Jr in a trade. I had it for over a year, but with many other amps to chose from, it never got played. To my ears, it didn't do the Fender thing very well at all and sounded really boxy. I looked into modding it, but for the time, effort and money required I decided the my energy would be better spent elsewhere, so I ended up trading it off.

[Mike62Jazz]

Hi Mike.. I know you saw the amp here.

I'm really not very impressed with it but I guess I have to concede that it is better the a stock one.
It still has some power supply hum even with the new power tubes that are idling at 9 watts each.

I've been messing with it for a couple hours and I've changed a couple caps on the board to get rid of some artifacts this one has.
But I've also discovered a nasty 12Khz- 16Khz oscillation that the push pull pot switch wiring, with respect to the NFB, ribbon cables and OT primary leads has created.
This is some of the fizz I've been hearing.
I've been moving all these wires around and can make it worse or a little better but I haven't found the combination yet that rids it 100%.
I rewired the NFB wire to go around the filter caps and that helped a very little bit but the oscillation is still there at medium loud levels.

It is the cream colored board and the FET amp is built on cheap crap Radio Shack perf board.
I'm not entirely sure what the mod is DPDT supposed to do either.
I don't have any paper work and the side of the DPDT switch it is connecting a ground to one of the lugs on the foot pedal switching stereo, pedal jack.
Since the original jack isn't switching stereo jack, I assume this is so you can foot pedal the amp or boost or both?
One of the sloppy solder joints on the dual power supply caps has come loose and the stock E-cap has a bad solder joint on the other side creating a horrible blapping noise at most low frequencies.
The master volume pot is bad and is crunching when rotating.
The second preamp tube socket is bad and the amp shuts off every once in a while.. etc, etc, etc.
These amps are just clock radio PCB junk and modding the hell out of them seems dubious to me.
What's kind of funny is the owner of this one tries to gig with it once or twice a week and he's complaining that it seems to break down frequently.

Well, that's quite a few issues! I started modding mine just to learn a little about amps and electronics. Mine also doesn't leave my studio. Check Bill Machrones' site for help in dressing the ribbon cables to get rid of the oscillation Billm Audio Billm Audio Blues Junior Mods
It sounds to me like MOST of the problems are due to the mods. Remember, I'm a bassplayer so take anything I say with a grain of salt! Also, check out this page http://billmaudio.com/wp/?page_id=115

[Groover]

All the above makes me think I will eschew the mods, and continue to use the amp as the useful and reliable tool it has been for years.

[Bruce / Mission Amps]

...
It sounds to me like MOST of the problems are due to the mods. Remember, I'm a bassplayer so take anything I say with a grain of salt! Also, check out this page Billm Audio Cream Board Phase Inverter Oscillation

That's the one to read... I'll try the shunt and see how that works.. I'm sure that this is a common problem after reading all this.
_________________

OK moved it all around and did the ribbon cable thing.. which I had already been doing. It is better but installing the 100pF cap across the 100K load resistor got rid of most of it.
So I'm done with the toy Fender amp.

[TheTinMan]

These amps are just clock radio PCB junk and modding the hell out of them seems dubious to me.

That pretty much sums up my opinion of the Blues Jr. It was my first amp, bought in 2001 (green board). Weber Blue Dog speaker was the best bang-for-the-buck mod ever IMHO. I added adjustable bias, although not quite the way Bill Machrone suggests. That plus experimenting with various tubes got me a decent amp, except for the reliability problems.

The input jack is pretty much shot now, the board mounted pots are going scratchy, I've re-soldered all of the tube socket points, and every time I even look at those damn ribbon cables some new noise starts up.

By the time you've done half of Bill's mods, you might as well build a Hoffman 18-Watt Stout with reverb in the damned thing. Gutting mine is on the list - just haven't decided which circuit to put in there.

Cheers,

Chip

[peppercalhoun]

I have been playing through my junior for 10 years,did the Bill M mods after I recorded a cd with it,and have used it since at festivals all over the south because iy's got the sound I want.First off,I bought a used vintage30 on evil way for $60,did the basic green board mods,bought the cap pack kit from torres,use jj power tubes,vintage ruby's in v1 and v2,and a jj 12at7 in the PI-no extra noise,no breakdowns,no problems for8 years,did the mods,and still no problems.I get compliments on the tone all of the time,even from blues festival players and legends.If you do the nods correctly on an amp that is in good working condition,then you will have good results..That said,stop hatin' on the little workhorse and play some music,already!!! Happy modding...

[Feramentum]

I have been playing through my junior for 10 years,did the Bill M mods after I recorded a cd with it,and have used it since at festivals all over the south because iy's got the sound I want.First off,I bought a used vintage30 on evil way for $60,did the basic green board mods,bought the cap pack kit from torres,use jj power tubes,vintage ruby's in v1 and v2,and a jj 12at7 in the PI-no extra noise,no breakdowns,no problems for8 years,did the mods,and still no problems.I get compliments on the tone all of the time,even from blues festival players and legends.If you do the nods correctly on an amp that is in good working condition,then you will have good results..That said,stop hatin' on the little workhorse and play some music,already!!! Happy modding...

Damn right! this amp hits every KR Stones lick and ticks like a Timex. I did the mods for the amps versatility to expand to what it's capable of. Playing in open G, the center of dynamics is a hair different. I have a Vibro King, JCM 800 4212, JCM 600 2x12, a 5150 combo, A full marshall 9200 rack with all the trimmings....... guess which amp gets played daily? The sweet little junior so all you purists that knock the little dude for playing with sound and blowing dollars chasing tone on the skids, more power to them. Who cares if you can't drop it 10 feet to the concrete floor or it has some circuit board. 99 percent of the people in here can't solder a speaker terminal anyway let alone build tone unless some posterboy uses equipment they think they need. The Junior Rules.

[Mick Bailey]

I've carried out these mods on quite a few amps. The adjustable bias is an improvement (though sonically makes little difference), and increasing the coupling caps to get a little more bass and lower-mid helps to a degree. If you replaced everything including the speaker and cabinet, it could be an excellent amp. If you take the amp as it stands and put it through a bigger cab with a G12H it sounds pretty good. Pity about the shoddy build. The tips on fixing lifted tracks on the BillM site are there with good reason.

The pots aren't over-spec'd for a child's toy, the input jacks are a crime against humanity and the the only reason the PCB isn't made from cardboard is that they found something cheaper.