Fender Blues Jr - Mods

[gordo]

I've done a bunch of BillM mods for buddies.  I'm not really sure that it's in anyone's best interest to let the cat out of the bag in terms of just giving away the mods.  I agree though that the ordering process is brutal and that goes back to when Bill was still healthy.  That said, yes, if the amp is that bottom heavy in terms of tone there's definitely something going on.  That's a real nice tube set and it should sound very bright.  Most of the BillM stuff involves getting rid of the shrill top end and adding a bit of punch to the low end by stiffening up the power supply.  I'd play thru another speaker to make sure that it's not a speaker problem first.

[midwayfair]

Nah, I bought it used.  I have played my friend's.  It's gorgeous and the reason I bought mine.

You still haven't clarified if you compared yours to another stock Blues Jr. and whether it sounded different. It's boxy sounding for sure but it shouldn't be as dark as you seem to be describing.

[culturejam]

I can't even figure out HOW to order a billm mod kit. The web site is confusing. I would think the "mod kits and services" page would be it, but that page is password protected. WTF?

[brucer]

I can't even figure out HOW to order a billm mod kit. The web site is confusing. I would think the "mod kits and services" page would be it, but that page is password protected. WTF?

I think the store is still closed from January.  The "News for January" says "The Billm Audio web store will not reopen until the current backlog of orders and amplifiers has been filled: I am loath to provide an estimate."

[gordo]

I reread my post and it sounded a little soap-box preachy.  What's everyone's take on this? Is it fair game if you can't place an order now or what?  Or is intellectual property still IP.  Given the nature of our adventures here maybe I'm being too close minded?

[brucer]

I reread my post and it sounded a little soap-box preachy.  What's everyone's take on this? Is it fair game if you can't place an order now or what?  Or is intellectual property still IP.  Given the nature of our adventures here maybe I'm being too close minded?

I thought you were on the mark.  Billm has put a lot of effort into learning and tweaking that amp and others, then putting kits together to make a business.  Seems fair to give him his due by not sharing what he's asked folks not to.  To me, at least, but I'm rife with contradictions so ... that's less than useful. 

[culturejam]

I reread my post and it sounded a little soap-box preachy.  What's everyone's take on this? Is it fair game if you can't place an order now or what?  Or is intellectual property still IP.  Given the nature of our adventures here maybe I'm being too close minded?

Good topic for a discussion. 

From a legal perspective (and midwayfair may have some better insights than me), I'm not sure how you can protect the concept of changing component values, replacing a transformer and speaker, and making other modifications to an electronic device. Certainly the document that contains this information can by copyrighted (and is automatically copyrighted upon creation, as is any document or photograph or drawing, etc). But I don't think there is anything specific in those mods that is "non-intuitive" and thus protectable.

Let's look at it another way. Suppose you decide you're not going to pay for the billm mods and you're going to experiment for yourself and find out what works best. You spend some time modding the amp and testing, making notes as you go. Then you decide to share your findings with world by publishing this information online. Turns out that most of what you discovered is exactly what's in the billm mods document. Are you violating his "intellectual property" by posting your findings? Is no one allowed to publicly discuss  Blues Jr mods that are similar to billm's because now he owns the idea of modding a Blues Jr?

I think not.

Now, that's not to say that I per se advocate that someone should info-dump his mod documents on the web as a free-for-all. But I'll say that I am *stunned* that after all this time, not a single person has summarized the mods in their own language and posted it online somewhere. Stunned, I say.

[Bret608]

I actually did find a run down of his mods on an ancient TGP or telecaster forum post (damned if I can find it now, though). I seem to remember him and Fromel discussing the merits of some of the mods. I ended up ordering his kit as the price didn't end up much worse than if I'd pieced it together myself. The documentation was helpful for sure. I agree with Pryde though about the order of priority. The tone cap mods might not be for everyone.

[daleykd]

Great discussion, and I greatly appreciate it.

I think I am curious about finding the information online only because there's no guarantee that my money wasn't a waste.  As someone who has an e-commerce site, I couldn't fathom finding it acceptable to sell a kit and not ship it for 6 months with no communication.  And there's no way for me to ask for a refund.

I mainly wanted the kit for the bias information.  I've had multiple people say "cool those tubes!"  I also wanted the information on how to fix the reverb for the green boards.  Heck, if it was a locked page that he gave you a key to when you paid him, I'd be happy with that!

At this point, if a trustworthy amp tech lived closer to me, I'd just take it to him.  I just don't feel like driving an hour to get to one.

I actually did find a run down of his mods on an ancient TGP or telecaster forum post (damned if I can find it now, though). I seem to remember him and Fromel discussing the merits of some of the mods. I ended up ordering his kit as the price didn't end up much worse than if I'd pieced it together myself. The documentation was helpful for sure. I agree with Pryde though about the order of priority. The tone cap mods might not be for everyone.

I read this at one point, too, so I know it's there.  However, I couldn't FULLY decipher it.

[midwayfair]

I mainly wanted the kit for the bias information.

Buying a kit for that reason is ... well, don't do that. Learn how to bias the amp, and then bias it according to the tubes you actually have.

WATCH BOTH. Don't skip the first one.

And I'll also preliminarily say that running your tubes colder is not going to give you a clearer tone or better bandwidth.

[matmosphere]

I mainly wanted the kit for the bias information.

Buying a kit for that reason is ... well, don't do that. Learn how to bias the amp, and then bias it according to the tubes you actually have.

WATCH BOTH. Don't skip the first one.

And I'll also preliminarily say that running your tubes colder is not going to give you a clearer tone or better bandwidth.

Fixed the YouTube links, because I'm interested to watch them.

[alanp]

MetroAmp's 50W Plexi kit build doc is worth reading for the bias section.

[daleykd]

First, I learned something this week: if I turn all 3 of the tone knobs up to 12, it sounds much better.

I've done a lot of reading this last week on the mods (still no word from Bill or his son) and have a much better understanding.  I've ordered parts from Mouser to replace the tone caps, coupling caps, and main 47uF.

The only thing I can't quite grasp is how he did the sparkle mod.  Has someone done this before?  It's an A500k push/pull pot, with (what looks like) a 3n3 cap on one of the switches.  You pull out the voicing cap and replace one side with the wire.  Problem is, I can't quite tell how everything is wired up on the pot.

Thanks for all of your help.

[I plan on taking my stock Blues Jr to my friend's house tonight and comparing it apples-to-apples with his stock Blues Jr.]

[thesmokingman]

if you can bear with me I'll run them all down for you(at work at the moment). I just came across this thread and I've done mods to both green and cream boards. The ones I don't care about (like drilling the chassis to add stuff) aren't included but I've done the tone, twin stack, reverb, standby, 4/8/16 Hammond transformer, etc. And you can save a lot of money because most of billm's mod parts are available over at antique electronic supply if you know where to look for them.

obviously some of his pages give you a straight rundown and instructions with values of what to do like the following
http://billmaudio.com/wp/?page_id=58 - twinlike mid knob
http://billmaudio.com/wp/?page_id=34 - fixing green reverb
http://billmaudio.com/wp/?page_id=141 - cathode follower
Original Fender® Part Number 00373230000 - better reverb taper pot, better master volume taper as well both 50KB stock, changed to 50KA
Tube compliment for maximum clean headroom with cathode follower mod v1 12AY7, V2 12DW7, v3 12AT7
Hammond 1760F 4/8/16 output transformer for Blues Jr
Granted I'm not home to check my amp but I believe he swaps the 22n bass cap for 100n like the blackface twin. he also swaps the 22n mid cap for a 15n as well. If you wanted a true blackface twin tone section you'd need to change the taper of the bass pot to an audio taper and change the mid pot from 25K to 10KA and the mid cap to 47n.

Sparkle mod changes c35 on a green board (c9 on cream) from 1.5n to a variable from zero to 3n. zero would be series III value, 1.5n is stock series 1 or 2, 3n is darker than useable(imo). I waited on this mod to last and voiced it accordingly. I found stock on the series one and two to be darker than "the fender sound" I was looking for. Also consider removing and jumpering the 33n capacitor at C19 (c10 on cream board)

presence control changes negative feedback resistor r26 from 7K5 into a 10K pot.

Mod brand reverb tank https://www.tubesandmore.com/products/P-RMOD-8EB2C1B
btw the long decay version doesn't play well with the green board even after the mod

power stiffening mod - adds a second 47uf cap in parallel with the 47uf in the power supply
fixed bias mod - increase r31(r52 cream board) to 27K
off standby on switch - https://www.tubesandmore.com/products/P-H520
green board instructions
4 poles left to right, top to bottom numbered 1-4 (pole 1 oriented middle of switch body, left hand side when looking at switch)
pole one to black lead from S2A, pole two to CP12(remove existing lead at CP12), pole three to black power cord lead, pole four to lead that was at CP12

cream board instructions
same switch orientation and labeling as before
pole one to black power cord lead, pole two to CP11 (remove existing lead at CP11), pole three to black lead from S2A, pole four to lead that was at CP11

I will say the best modification for this amp is by far a new speaker and a larger cabinet or switching this to a head unit.

[daleykd]

Granted I'm not home to check my amp but I believe he swaps the 22n bass cap for 100n like the blackface twin.  I think he also swaps the 22n mid cap for a 47n as well.

You're right on the bass cap.  Mid is changed to a 15n.