DRRI in for "Hand Wired" conversion

[bnwitt]

Well I've got a Fender Deluxe Reverb Reissue in for conversion to a Hoffman AB763 "Hand Wired" version.  I've seen the website that's out there on this job and was wondering if any one in here has done one of these.  I've done lots of late era silverface conversions to original Fender layout on G10 FR4 and several scratch built Hoffman AB763's in Vibroverbs(I still think the Hoffman AB763 SRV amp you guys helped me layout is the best sounding blackface ever) but never a Deluxe Reverb reissue conversion.  Anyone have any tips or tricks before I get started?

[Geezer]

http://www.el34world.com/Hoffman/instructions.htm

Barry, Maybe this will help(?)

[Dave]

The chassis is almost just like a real DR, so, its not that bad. Beware of that PT though, if you choose to replace it with a "better" one, the DRRI PT is longer and wider than an original.

Dave

[sluckey]

MM makes a drop-in replacement for the DRRI PT.

[bnwitt]

Thanks everyone.  I believe I'll be keeping the orginal PT but might change the OT.  I'm afraid I can't see the price value in any MM trannie.  They are just to darn expensive for what you get.  Heyboer is fine with me.  Geezer, that's funny brother.  With over 60 Hoffman style amps under my belt since the late 90's you link me the Hoffman board installation instructions.  Love ya man.   Dave, thank you brother.  That's the kind of data I was seeking.

[Dave]

You bet!

Dave

[Geezer]

Thanks everyone.   Love ya man.  

Always happy to help a newbie out 

[bnwitt]

Ok fellows, the first thing I notice is the RI has the reverb jacks in the bottom of the chassis using a pcb break off board piece instead of on the back panel area.  I guess the quality assurance sticker which is on the area where I need to put new jacks is a gonner.  I'm tempted to have a whole new rear panel made and dump the fender unit altogether. Any opinions?  The owner is a session player so I doubt he'd care if I used a label maker.

[sluckey]

I'd probably just put the reverb jacks on the bottom and not mess with the back panel. Kinda like this...

[bnwitt]

so you pulled the original jacks and used 1 of the original holes along with a drilled new one?

[nateflanigan]

I just powered one of those up this weekend, it sounds like you've got about 60 times the experience I have with hoffman amps so I'm not sure how useful I can be, but...

I decided to use a bigger PT to accommodate 6L6's, I had to enlarge the whole but it really wasn't a big deal.  I mounted the reverb jacks on the back.  I mounted the board a little too close to the front, I messed up the wiring on the input jacks and it was really hard to repair. 

Hope that's useful

[sluckey]

so you pulled the original jacks and used 1 of the original holes along with a drilled new one?

Actually, Mikey Mann did that one, but That's how I will do my TRRI, if/when I ever get a round tuit. That pic came from this website. There's a lot of detail and minutia told by a non technical person documenting Mikey's rebuild. Maybe too much fluff for a technical person, but there is some good info too. And Mikey knows his stuff.

http://deluxereverb.waynereno.com

[Fresh_Start]

Ok fellows, the first thing I notice is the RI has the reverb jacks in the bottom of the chassis using a pcb break off board piece instead of on the back panel area.  I guess the quality assurance sticker which is on the area where I need to put new jacks is a gonner.  I'm tempted to have a whole new rear panel made and dump the fender unit altogether. Any opinions?  The owner is a session player so I doubt he'd care if I used a label maker.

Don't know what the back panel of a DRRI looks like, but my layouts worked a lot better when I ditched the Mojo back panel layout and did my own.  Using existing holes where possible of course.  Especially knowing you want bias test points, etc.

Chip

[bnwitt]

That pic came from this website.

I saw that site.  Mercury Magnetics ought to pay for his webhosting bill.  He sure sells the PT change for them.  Does Mike Mann actually have his own site?  

I am going to put bias test jacks on the back panel but I'm going to put the bias pot back there too so you don't have to reach in under the hot tubes to bias the amp as you do with it in its factory position.  What do you guys think of Mikey's cap stacking?  Seems a bit much to me.  Chip, I think putting jacks as close to their component connection is the way to go for sure.  That's why I asked about the reverb jacks.  They're down between V2 and V3 instead of between V3 and V4 like they ought to be.  Of course that puts them on the back panel because of the cap can.  You can see in the attached picture of the back panel that the footswitch jack is in the way of the reverb jacks' best location too but I can squeeze them in on the right of it.

[Fresh_Start]

That pic came from this website.

I saw that site.  Mercury Magnetics ought to pay for his webhosting bill.  He sure sells the PT change for them.  Does Mike Mann actually have his own site?  

I am going to put bias test jacks on the back panel but I'm going to put the bias pot back there too so you don't have to reach in under the hot tubes to bias the amp as you do with it in its factory position.  What do you guys think of Mikey's cap stacking?  Seems a bit much to me.  Chip, I think putting jacks as close to their component connection is the way to go for sure.  That's why I asked about the reverb jacks.  They're down between V2 and V3 instead of between V3 and V4 like they ought to be.  Of course that puts them on the back panel because of the cap can.

Too much MM hype throughout that presentation.

Cap stacking?  I think if you "need" a .057uf coupling cap after the PI, then you ought to buy a .056uf cap and move on.  I also think that you could go .047 or .068 and tweak the tone pots a smidgeon to make up any perceptible difference.  Sorry if I'm knit-picking.

BTW does the author ever explain WHY the original amp was eating 6V6 power tubes and frying 470 ohm screen resistors?

I also like the final "tweak" to change the cathode resistors for the first preamp stages from 820 ohms to 1.5K.  Somebody wasn't paying attention to Doug's drawing.

HOWEVER, Waynes does have very nice things to say about Doug Hoffman and this forum.  Still, he should've bought his transformers here unless MM gave him a BIG discount...

Chip

[bnwitt]

Right on the far left of the back panel under the caution verbiage there is a panel mounting screw.  Just to the right of that screw under the panel is a switch sized unused hole in the chassis.  It's up high off the center line of the chassis back panel but I may try to use it for the bias pot and put the test jacks to the left of it.  I think a new laser rear engraved back panel is in order here.

[bnwitt]

One of the differences in the reissue from the original BFDR is the power section filter cap values.  The BFDR had all 16uf filter caps with two in parallel for 32uf on the first stage with 450 volts rating.  The reissue has a 220uf 100 volt and a 47uf 500 volt in series for around 39uf with 600 volts rating combined and then 22uf caps for each subsequent stage.  However, the one I'm gutting has a 220uf 300 volt rated cap so the first stage is 800 volts rated.  So what's up with that first stage change?  I've seen a lot of original BFDR amps in here for service and I've never seen blown first stage caps.  39uf doesn't seem like that much of a boost either.  That seems to be the only change from the original schematic from a quick glance.  Seems like Fender engineering just needed to feel like they put in some tweek for the reissue.

[bnwitt]

Well the owner has decided he wants the roach trem so I'll be doing an original Fender layout now.  Attached are the boards for anyone who is interested.

Edit:  new attachment has signal and B+ jumper wires shown on main board and screws in positions to match mounting locations for cap board on DRRI.  Also screws for main board are now in locations that do not interfere with exterior chassis mounted components.

[bnwitt]

I guess the projects I choose are boring or something.  I get all kinds of views on my threads but very few posts for some reason.  I hope for feedback and discussion on what I feel are just classic Holy Grail amp circuits but there doesn't seem to be much interest in the amps I choose.  The Magnatone Custom M10  gleans more interest then Leo’s Deluxe Reverb in this forum for some reason.  Holy crap!!  Really!!?

I've come to the conclusion that my tastes are somewhat avant garde now even though at one time they were main stream.  I think it's time for a personal sojourn of experimentation on Leo’s and Jim’s work.  I could care less about a Magnatone Custom M10 or a Silvertone 1484.  I don’t think too many great tracks were cut with them.  Rock and roll is Marshall, Vox and Fender and I think I shall pursue the tweaking of those circuits with my decade boxes on my own.  I think there are those that think “Been there done that.”,  when in fact the surface has just been scratched on these great holy grail amps.  Beatles, Stones, Cream…..No Magnatone, no Silvertone no obscure contraptions.  My quest for tone shall return to it’s roots.

Sometimes I wonder if most tube dudes are really seeking tone, or just gadgetry or novelty.

[gregarious]

Barry, your posts I have read where you challenge Leo's designs are thought provoking in their consideration and reveal attributes about these circuits which help explain & verify the reasons they have earned their appeal and following. If my understanding was a fraction of yours, I could offer an intelligible comment.

There is a lot of merit in the classic circuits (just ask Richard Kuehnel!), which the many iterations of 5E3, 5F6a, AB763, ect and derivations attests to.

Your help in understanding the "seasonings" of these circuit arrangements that dissecting the building blocks lead to, is a credit to your knowledge and diligence.

Your contributions on Fender inspired layouts is stellar. Thanks for everything.

[LooseChange]

I love the Fender tone... I've tweaked the heck out of them.
Your layout looks great.

What do you want to discuss regarding this circuit?

[Dave]

Midol?

[Fresh_Start]

Barry - what does the owner want in terms of the "Normal" channel?  My Super Reverb build with a normal "Vibrato" channel and a fairly abnormal "Normal" channel turned out really well in terms of a happy owner/player.  However, there are so many possible directions to go and they all depend on the guitar player.  I went Brown Vibroverb/Deluxe and seem to have hit a homerun, but I'd love to do another AB763 with tremolo and reverb on both channels and try to get close to Marshall tone on one channel.  Steal a triode from the reverb driver for the cathode follower maybe?  MOSFET cathode follower?

My guess is that you are well known in our small community and most of us have so much less experience than you do.  That makes it harder to make suggestions.  

Here, I can't imagine that the amp wouldn't benefit from a new OT - from Doug!

Cheers,

Chip

[sluckey]

The Magnatone Custom M10  gleans more interest then Leo’s Deluxe Reverb in this forum for some reason.  Holy crap!!  Really!!?

Why do you say that? At the time you posted this, there were 18 replies on this thread and 18 replies on the Maggy thread. Sounds pretty even to me.

OTOH, new AB763 topics pop up weekly, maybe even more frequently. Maggie topics pop up rarely. I'd say that AB763 is a much more popular topic.

[phsyconoodler]

Barry,
  I've done about eight DRRI hand wired conversions now,and only one had MM iron used.All sounded quite a bit better than the stock PCB units.I just move the RCA jacks closer to the back panel,because the stock board width covers part of the DRRI reverb RCA's.I just make a small aluminum cover over the stock hole in the chassis.
   The stock transformers sound just fine.
  I did one where I just used the stock filter cap board but removed the bias cap.It does sound better with a new board with the original 20uf caps.
  The MM output transformer sounded too dark for my tastes;the stock one has more highs.
The hand-wired ones have more harmonics,break up nicer and the reverb is better sounding.The DRRI pots suck in the extreme,so a set of CTS or Alpha pots really help the sound of this amp.
  I used both Mojo Dijon and Mallory 150's coupling caps.Both sound really nice.WAY better than the stock stuff.
Every one of the conversions sounded better than the stock DRRI.Side by side comparisons were proof.

[tommytornado]

I've done one of these conversions..  I really wish I would have replaced all the tube sockets.  The one's that come in it are cheap cheap and it's real easy for solder to slide down into the socket holes.  If you don't change them, make sure you have a tube plugged into the socket you're soldering on.  Also, on the one I did the reverb pan that came with it ended up sounding great.  And, I put the reverb jacks and added mid pots on the back of the chassis.  I just turned the back pannel over, leaving the entire back of the chassis accessable, leaving the tubes still protected.   

[PRR]

> I wonder if most tube dudes are really seeking ... just gadgetry or novelty.

Yes.

> I hope for feedback and discussion

You know your stuff. "...you've got about 60 times the experience". Once you write it up, there's not a lot left.

I am puzzled by what "discussion" you want. You seem hung-up about where to put reverb jacks? What size transformer? Leo and White wudda shoved the chassis under the drill-press and whirrrrr.

> What do you guys think of Mikey's cap stacking?  Seems a bit much to me.

If a 0.570u cap turns you on, do it. Some tweakers swing that way. I think it is silly. I doubt any experienced builder/tweaker is going to change his ways from some forum chatter.

> from 820 ohms to 1.5K.  Somebody wasn't paying attention to Doug's drawing.

Not looking at you, but an AWFUL lot of "issues" that I see in DIY audio (including mine!) are wrong values, wrong pins, wrong connections, just getting close to right.

> reissue has a 220uf 100 volt and a 47uf 500 volt in series

Somebody was inelegant. It may be a result of odd cap pricing or existing inventory. It aint mojo. I've used thirteen 39 ohm resistors, but one 20W 500 ohm would be more elegant.... the 39 ohm resistors fell off a truck.

[bnwitt]

Midol?

Dave, you are just frickin' hilarious  and I love ya  Guys, don't get me wrong, always remember as my signature says "don't take me too seriously".  Phsyco, that's exactly the kind of stuff I'm looking for.  Fresh Start, Loose change, PRR and everyone else, what I am looking for may be unobtanium (did anyone else think that word in Avatar was just stupid?)  I don't know, I just think some of Leo's and Jim's designs are absolutely fantastic and I guess I want perfection with modern technology and the help of years of analysis to tweak them.  You know it's easy to list the new DRRI's weaknesses.  Those two undersized 470 ohm resistors on the power tubes that burn up all the time is one thing.  In fact I can name hundreds of weaknesses from modern amps because of cheap profit mongering  CEO's.  What I want to do is take the holy grail accidents (let's face it they also went cheap back then but Americans made parts then) and make them HOLY GRAIL!!!  I don't think we need MM $300 trannies to do it but simple improvements instead.  That's what I'm looking for.  And Gregarious, don't think you have nothing to contribute.  You do friend.  Joe the plumber is no idiot.  He's an American I want to hear from.  He's a pulse.  A man of experience where the rubber meets the road.

Steve, I can say that because I want to shock the real brains in here into sharing their epiphanies with me.  To open my mind.  To tell me something that is in their head that I have never thought of.  To share with me something they've learned the hard way that I have yet to labor over.  This forum is a tremendous brain trust with mega power.  Come on, Shake, rattle and Roll!  The BFDR is an awesome amp!  If I had to choose 3 amps the BFDR, the Vox AC15 and the Marshall 18 watt would be the three I would put on stage along with my Tore T Revibe.

[Geezer]

unobtanium (did anyone else think that word in Avatar was just stupid?)

Absolutely......I actually liked the movie (if I ignored the political undertones), but that was just ridiculous. 

[Dave]

Not to defend Avatar (I haven't seen it and don't intend to), but its my understanding that the term was not coined by the writers of the movie. Apparently it has been in use for many years in the scientific community.
It is used to refer to anything that doesn't exist but would be useful.
I think a good example in tube amp building would be a variable capacitor (capaciometer).
"Sure could use a capaciometer right there to get more control over the tone."
"Yeah, good luck with that and all your other wierd unobtanium ideas"

Oh, and all those theoretical elements that could reside on the far eastern side of the periodic table but don't because they don't exist are referred to as unobtanium.

Dave

[phsyconoodler]

Naw,unobtanium is that stuff they're trying to mine on Pandora.
 
 Barry,the stock transformers sound just fine to me,even side by side with a blackface Deluxe.The cheap-ass parts fender uses is the number 1 reason they don't sound that great stock.

[drew]

"Unobtanium" has been used in the car and bike racing world for a long time to describe special parts which factory teams develop for their own use but don't make available for purchase by privateers.

Thanks for sharing another nice drawing, bnwitt.  Could I ask, when you are going to do a new Visio layout, what exactly are you using as a starting point, in terms of a file or template?  I have a copy of the program, and various saved libraries of electronics stuff for it (incl. I think some of yours), but I've just never figured out how to do anything other than pretty crude versions of Hoffman-style layouts, which I'm sure I don't have set up in a way that takes advantage of all (or nearly any) of the program's capabilities.

[alerich]

Cap stacking?  I think if you "need" a .057uf coupling cap after the PI, then you ought to buy a .056uf cap and move on.  I also think that you could go .047 or .068 and tweak the tone pots a smidgeon to make up any perceptible difference.  Sorry if I'm knit-picking.

Mikey's cap stacking is about tonality as opposed to values, if I understand it correctly. He suggests that using two smaller caps of different tonalities add to the correct value an give a certain tone that is unavailable by either cap separately at the same value. I'm skeptical but if it makes him feel good then do it, I say.

I remember when Mercury first came on the the scene and it was the new hot fad. Now that they have scads of transformers in play people have come to realize that they are different - not necessarily better or worse just different. And pricey.

[bnwitt]

Could I ask, when you are going to do a new Visio layout, what exactly are you using as a starting point, in terms of a file or template?

Drew,
I usually start with a similar file I have created previously if there is a similar one.  In this case I had done a black faced Twin reverb Fender style layout on G10 FR4 already so I just had to change a few components for the DR and draw a new cap board.  I have been using Visio since 1994 (before microsoft bought them) so using it is like walking to me.  I use the program for my solar designs as well even though I have cad programs because the interface and the drag and drop is so great.  The templates I have shared in the past have been added to over and over.  If I don't have a component in a template and their is a chance I will use it again it goes into a template and I never have to draw it again.  I've done that with the Fender low wattage amp cap boards and the high wattage cap boards now.

Anytime you see a pdf file of mine that you want in Visio, just email me and I'll send it to you.  I share everything because that's what other great tube people have taught me.  One of my favorite quotes is from John of Salisbury where he said, "We are like dwarfs sitting on the shoulders of giants. We see more, and things that are more distant, than they did, not because our sight is superior or because we are taller than they, but because they raise us up, and by their great stature add to ours."

[bnwitt]

Mikey's cap stacking is about tonality as opposed to values, if I understand it correctly. He suggests that using two smaller caps of different tonalities add to the correct value an give a certain tone that is unavailable by either cap separately at the same value. I'm skeptical but if it makes him feel good then do it, I say.

Yeah I get that concept and I'm skeptical like you.  Mainly because I have old man ears instead of the dog ears some players do.  I'd never be able to hear it myself and without a toggle switch A/B double blind test with a placebo switch test as well, I doubt we could ever be able to prove it.  I hope that is what Mikey did with numerous test subjects to justify the statement of it's worthyness.  I just think there are way too many "gut" personal individual beliefs in the audio world which are touted but never proven.  So, I take everything with a grain of salt.