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Hoffman Amps Forum image Author Topic: Lord I forgot how long it takes to build a Hoffman Deluxe Reverb  (Read 14238 times)

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Offline bnwitt

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So I was building my Hoffman AB763 Deluxe reverb for the studio (taking my own sweet time on it) and one of my "good friends" talked me out of the darn thing.  To make matters worse, after I agreed to sell it to him for almost what I have in it for parts he got in a hurry to have it.  So, I've been building it over the holiday weekend to get it done so I can move on to the next one which will be mine and lord I forgot how much there is to one of these amps.  Holy crud.  So many connections to make.  Kind of makes me want to put the next one off for awhile
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 Oh yeah, and I'm usually just kidding so don't take me too seriously.

Offline Ritchie200

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Re: Lord I forgot how long it takes to build a Hoffman Deluxe Reverb
« Reply #1 on: July 05, 2017, 12:12:29 am »
Barry! 

Great to see you back!  Don't be such a stranger.  Hope all is well with you and yours. 

With all those connections you would think it would sound better than it does! :angel  Fender.... :m16

Jim :icon_biggrin:

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Offline TIMBO

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Re: Lord I forgot how long it takes to build a Hoffman Deluxe Reverb
« Reply #2 on: July 05, 2017, 12:28:19 am »
Awesome!!
Looks great  :icon_biggrin:

Offline Ed_Chambley

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Re: Lord I forgot how long it takes to build a Hoffman Deluxe Reverb
« Reply #3 on: July 05, 2017, 10:01:47 am »
Well it looks like you got it going.  It is a dual channel, Reverb, tremolo amp.  Yep, lot of stuff.  I can assemble one in a day, a long day and that is only if I have a kit version.


You could always build a single channel with a loop. :laugh: Take a lot less time.

Offline bnwitt

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Re: Lord I forgot how long it takes to build a Hoffman Deluxe Reverb
« Reply #4 on: July 06, 2017, 09:22:41 am »
...With all those connections you would think it would sound better than it does! :angel  Fender.... :m16

Jim :icon_biggrin:

Jim, you are so funny.  :l2: And spoken like a true Marshall fan.
Barry
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Offline bnwitt

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Re: Lord I forgot how long it takes to build a Hoffman Deluxe Reverb
« Reply #5 on: July 06, 2017, 09:30:55 am »
You could always build a single channel with a loop. :laugh: Take a lot less time.

Ed, Well the full Deluxe Reverb is so versatile I think it is one of the Holy Grail amps which belongs in my studio.  Unfortunately I mentioned it to a friend who covets it and now I have to build another one for me.  With the 4 or 5 Vibroverbs I've built and that many BFDR reissues I've converted I've done this circuit about ten times now and have always been impressed by this amp.  I am no longer foolish enough to try to make a profit building them as it is just to labor intensive to get any return on the time. I do have a Revibe in the studio so maybe for me the single channel would work.  I'll have to explore that.  Thanks for the feedback.
Barry
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Offline bnwitt

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Re: Lord I forgot how long it takes to build a Hoffman Deluxe Reverb
« Reply #6 on: July 06, 2017, 09:32:58 am »
Awesome!!
Looks great  :icon_biggrin:

TimBo,
I don't know about looks great as that is never my goal and I don't think I'm hitting that here but I'm sure it will be quiet on idle and sound great.  That's all I really care about.  But thank you for the kind words. :icon_biggrin:

Barry
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Offline jojokeo

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Re: Lord I forgot how long it takes to build a Hoffman Deluxe Reverb
« Reply #7 on: July 06, 2017, 03:44:24 pm »
I am no longer foolish enough to try to make a profit building them as it is just to labor intensive to get any return on the time.
Hi Barry! Even though it seems like a pita it's not too bad. Just make it worth your while? Having my fav music and beverage nearby always helps. Mike churns these things out faster than you'd believe.


IMHO, There's no magic in having the first channel so build a lite version. Even leave out the Tremolo and use a pedal if/when you feel the need - no magic there either to the circuit and tone. But build everything remaining as it should be and be where you want with the least amount of hassle. I am also convinced that part of the magic of the amp's tone is the cabinet size. I would keep this as close as possible to spec. I would use the extra interior space to improve the layout, grounding, and lead dress shortcomings. I will say at my last outdoor gig playing alongside my bandmate's vintage '65 BFDR I had guys come up mid set complementing my tone over that. But it must've been because I used my custom 6v6 jcm/plexi mounted with a Scumback paper voice coil? It's a serious tone machine and waaay more versatile than a simple DR...
To steal ideas from one person is plagiarism. To steal from many is research.

Offline Ritchie200

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Re: Lord I forgot how long it takes to build a Hoffman Deluxe Reverb
« Reply #8 on: July 06, 2017, 05:07:00 pm »
IMHO, There's no magic in...




GASP!!!!!!!!  HOW DARE YOU YOUNG MAN!!!!  Shock treatments will commence immediately until you realize the errors of your ways.  Sweaty Teddy will install the back door probe.  Dick Dale will compress your noggin between two blazing Dual Showman cabs.  Eric Clapton will follow with his now famous plinky-plink version of Crossroads on his trusty Champ. This will immediately be followed by a loop of Neil Young's lead on Like a Hurricane, over and over and over and over.......and over....  We will have you goose stepping to Cat Scratch Fever in no time.  You WILL be assimilated into the collective. :happy2: 


Jim :icon_biggrin:

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Offline jojokeo

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Re: Lord I forgot how long it takes to build a Hoffman Deluxe Reverb
« Reply #9 on: July 09, 2017, 03:54:35 pm »
IMHO, There's no magic in...


GASP!!!!!!!!  HOW DARE YOU YOUNG MAN!!!!  Shock treatments will commence immediately until you realize the errors of your ways.  Sweaty Teddy will install the back door probe.  Dick Dale will compress your noggin between two blazing Dual Showman cabs.  Eric Clapton will follow with his now famous plinky-plink version of Crossroads on his trusty Champ. This will immediately be followed by a loop of Neil Young's lead on Like a Hurricane, over and over and over and over.......and over....  We will have you goose stepping to Cat Scratch Fever in no time.  You WILL be assimilated into the collective. :happy2: 


Jim :icon_biggrin:
:m17 :guitar1 

...once I thought I saw you in a crowded hazy bar, dancing on the light from star to star. Far across the moonbeam I know that's who you are, I saw your brown eyes turning once to fire...you are like a hurri

Yes, I am a bad bad boy... How dare I say "no magic"? He was as good a magician as Houdini to Copperfield. Did you ever catch his slight of hand act? Unbelievable! The wedding ring on the rope trick, the cigarette put out into her dress (but no damage) trick, the magic card tricks... I heard he never needed an eraser on his mechanical pencil set? Now that is impressive indeed.  :icon_biggrin:

Hold on there cowboy! Seriously, he made great musical equipment for a good price (depending how you look at it) but there's "no Magic" to what he did. It's easy to replicate his stuff and get the same (or even better) good sound and playability every time. Nothing magic about that - except only when I do it! :l2:  You? Not so much... :dontknow: Ha! But even :worthy1: you smoke Leo any day yeah? Big Kahuna or no big Kahuna
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Offline bnwitt

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Re: Lord I forgot how long it takes to build a Hoffman Deluxe Reverb
« Reply #10 on: July 10, 2017, 11:31:00 am »
Well I guess there are people today who smoke Sir Isaac Newton's work but in his time what he did was ground breaking and incredible.  The same goes for Leo.  Heck even Jim Marshall copied his work.  Not bad for a radio repairman.
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Offline Ed_Chambley

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Re: Lord I forgot how long it takes to build a Hoffman Deluxe Reverb
« Reply #11 on: July 10, 2017, 12:09:59 pm »

IMHO, There's no magic in having the first channel so build a lite version. Even leave out the Tremolo and use a pedal if/when you feel the need - no magic there either to the circuit and tone. But build everything remaining as it should be and be where you want with the least amount of hassle. I am also convinced that part of the magic of the amp's tone is the cabinet size. I would keep this as close as possible to spec. I would use the extra interior space to improve the layout, grounding, and lead dress shortcomings. I will say at my last outdoor gig playing alongside my bandmate's vintage '65 BFDR I had guys come up mid set complementing my tone over that. But it must've been because I used my custom 6v6 jcm/plexi mounted with a Scumback paper voice coil? It's a serious tone machine and waaay more versatile than a simple DR...

If I am building a Deluxe Reverb Blackface and do want to have the 2 channels, I still prefer to use a different chassis that has a mid control.  It is fairly easy to have a 2 channel amp the old school way and use a A/B pedal, but for Studio Amps, noise is the biggest problem.


My problem is I think of too many things I need more pots for.  I just finished an amp this weekend that started out as a AB763 Deluxe Reverb, but now it is a 1 channel amp with a custom faceplate and 2, 10"s ousted of 1, 12.  I started this for a friend who "said" he wanted a "exact" 65 Deluxe, what 65 has to do with this, I really do not know.


He was over and we were discussing the build and he has never played any of my amps.  Well I got a Deluxe with tons of mods like the ability to have a plate driven tone stack or CF stack, Raw, additional gain stage with switching Plate Resistors and Bypass caps with the next tube being s cold clipper.  Everything is manual as I built it before I began using 5 volt switching.  All the preamp tubes run DC.  Adjustable NFB, 2 master volumes, Pentode/Triode, you know all the junk.


It will do the perfect stock Deluxe Reverb AB763, but much more and I prefer the tone of 6V6 when in the CF mode, just sounds more Marshally whereas 6L6 Tubes don't get there.


And no, I do not think it is a good idea to build for sale amps, even though I do sell ones I am tired of, however money can be made on repairs and mods.  Well, after playing around with mine he decided to add some mods and when I installed a set of Tung-Sol 5881 stock went out the window.


Of course I was a little restricted with the smaller chassis, but was able to give him the mods I use often.  Tweaking the amp cost him more in labor than building the whole amp.  Herein lies the problem when we build.  We don't have to think of a market price point or are we building an amp that hurts another amps in the lineup value.

Offline jojokeo

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Re: Lord I forgot how long it takes to build a Hoffman Deluxe Reverb
« Reply #12 on: July 10, 2017, 01:02:15 pm »
Barry - I had written exactly your point but removed it. Saying, he is to be respected for sure for what he did when he did it. (but my poor attempt at humor would've been misconstrued?)


Ed, on iphone so hard to comment and can't post pics. But Tung Sol 5881s you say? This is my "definitely not a deluxe circuit" built into a 5E3. I used 3 of the 4 input jack holes for a Gain, Treble, and Bass. I then used the 1st Vol as a post tone stack Vol, the 2nd as a LarMar ppimv, and the Tone location ditched for a pushpull Presence pot.


Because the iron is way overrated for a basic 5E3 I biased it to sub the 6V6s AND 5Y3 for the 5881s and a 5R4. Many don't realize the 5Y3 can't put out the current needed when doing this? Anyway, the 5R4 is preferred over a 5U4 or 5AR4 because it gives about the same voltage drop as the 5Y3 (unlike 5AR4) yet handles the higher current (unlike the 5Y3 AND operates at 5V 2A unlike 5U4). Pointing these out for others to understand and learn from.



*Jimbo - life is short, don't blow it! Mahalo 🏄🏝🌋
« Last Edit: July 10, 2017, 01:09:20 pm by jojokeo »
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Offline EL34

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Re: Lord I forgot how long it takes to build a Hoffman Deluxe Reverb
« Reply #13 on: July 11, 2017, 05:42:33 am »
Welcome back Barry


Building a two channel AB763 turret board amp is a marathon event
Towards the end of the build, I was always ready for it to be over

Offline bnwitt

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Re: Lord I forgot how long it takes to build a Hoffman Deluxe Reverb
« Reply #14 on: July 11, 2017, 11:23:59 am »
Welcome back Barry


Building a two channel AB763 turret board amp is a marathon event
Towards the end of the build, I was always ready for it to be over

Yes sir Doug,  But thanks to your predrilled turret boards, it is a little easier :worthy1:  And now I have another one to do along with an AC15, Princeton, 2204 and (2) Marshall 18 waters I'm working on.  So many amps and so little time.
Guides on your quest for tone.
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Offline bnwitt

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Re: Lord I forgot how long it takes to build a Hoffman Deluxe Reverb
« Reply #15 on: July 11, 2017, 11:38:49 am »

If I am building a Deluxe Reverb Blackface and do want to have the 2 channels, I still prefer to use a different chassis that has a mid control. 

I always put a mid control in all of my AB763 amps as I think just having the fixed resistor cripples them.  But that's just me :smiley:  Also, if you make your own custom faceplate it's easy to fit it into the standard chassis.  Just drill one more hole and shift everything over one space.
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Offline Ed_Chambley

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Re: Lord I forgot how long it takes to build a Hoffman Deluxe Reverb
« Reply #16 on: July 11, 2017, 06:48:11 pm »
What is Duke?
I agree, fender amps need mid pots IMO. I like to even get one on the normal channel, but normally I put that on the bottom. I like having a extra speaker jack, one for like out and another for added cabinet.


I even added a mid on my 62 bass man, but I did not drill anything. Just a little box in the head with a pot in it.






Offline bnwitt

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Re: Lord I forgot how long it takes to build a Hoffman Deluxe Reverb
« Reply #17 on: July 12, 2017, 07:59:07 am »
What is Duke?

Well my amp company is Corona AmpWorks.  Corona being Spanish for Crown.  So, All my amps are named after crown wearing royalty like Reverb King, Duke 55, Duke 65, Baron 59 etc
« Last Edit: July 12, 2017, 09:27:06 am by bnwitt »
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Offline Ritchie200

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Re: Lord I forgot how long it takes to build a Hoffman Deluxe Reverb
« Reply #18 on: July 13, 2017, 01:38:41 pm »
Barry please post finished pics as your builds are always awesome!


Jim :worthy1:

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Offline bnwitt

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Re: Lord I forgot how long it takes to build a Hoffman Deluxe Reverb
« Reply #20 on: July 14, 2017, 12:39:59 am »
Jim,
I will post pics of the finished amp for sure.  Hey, I've got a question.  I'm running through the wiring and checking everything to the Hoffman PDF documents, and I noticed that on the layout without a mid pot (typical BFDR) it shows the standard 47pf bright cap on the reverb channel volume pot; but on the layout out with the mid pot, (which shows a bright switch assembly on the normal channel)  it doesn't show the bright cap on the reverb channel.  On the preamp and reverb schematic it shows a bright switch and the 120pf cap in place in the "mid pot and bright switch" box but in the "no mid pot, no bright switch" box it doesn't show the 47pf bright cap. It was my understanding that the 47pf bright cap is there to pass high frequencies at low volumes.  Should it be shown and installed with or without the mid pot if no bright switch is installed??  I mean, isn't it there in place of the bright switch/cap assembly to pass some highs?  Should the documents be updated or was this omission intentional?
Barry
« Last Edit: July 14, 2017, 08:47:10 am by bnwitt »
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Offline MFowler

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Re: Lord I forgot how long it takes to build a Hoffman Deluxe Reverb
« Reply #21 on: July 14, 2017, 09:14:44 am »
Barry,


Like you told me when I was building that Komet 60, you said your a resourceful guy you can do it.


You also tried to talk me into fixing my own furnance/replace it myself but I had it professional installed. :icon_biggrin:


Lot of connects to make in your amp for sure.  I always say the same thing everytime I built a Fender Twin Reverb, etc.  To much under board wiring for me.


Mark

Offline bnwitt

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Re: Lord I forgot how long it takes to build a Hoffman Deluxe Reverb
« Reply #22 on: July 14, 2017, 09:27:19 am »
Mark,
Hey buddy, it's good to see you're still doing the amping.  I hope all is well with you.  I still say you could have done the heater work yourself. :laugh:
Barry
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Offline PRR

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Re: Lord I forgot how long it takes to build a Hoffman Deluxe Reverb
« Reply #23 on: July 14, 2017, 04:54:16 pm »
> talk me into fixing my own furnance/replace it myself

I did it. From cracked old oil-burner to gas fired with A/C. Figured the BTU myself; spent all winter but then I knew what I needed and why. Had one pro hook the gas, another the Freon. Did my own plans and had a pro tin-knocker bend a new (right-size!) duct. Couldn't be happier.

Offline shooter

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Re: Lord I forgot how long it takes to build a Hoffman Deluxe Reverb
« Reply #24 on: July 14, 2017, 05:07:02 pm »
Quote
I did it.
+1
yup, same thing, same reason, n same pro's, although I did most of the tin-knocking :BangHead:
Only problem I had was I got a free Trane 8ton AC unit near new, the AC guy had a fit trying to plumb in the A coil. :icon_biggrin:
Went Class C for efficiency

Offline John

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Re: Lord I forgot how long it takes to build a Hoffman Deluxe Reverb
« Reply #25 on: July 14, 2017, 05:15:34 pm »
I installed my own wood stove!  :m16
Tapping into the inner tube.

Offline Ritchie200

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Re: Lord I forgot how long it takes to build a Hoffman Deluxe Reverb
« Reply #26 on: July 14, 2017, 06:50:29 pm »
+3

AC/Heat pump, Furnace, High efficiency box filter, UV light, Makeup air unit, New transitions (had to move return duct over for new filter assembly clearance and new tin for furnace to supply), Humidifier, New thermostat.  Finished all in two long days with my wife looking over me with bat in hand because it was winter and she was tired of feeding the wood furnace!  Easy peasy with this company:

https://www.alpinehomeair.com/

They even supply a DYI video that someone with two left thumbs could figure out.  They also sell all the tools and even handy install kits with everything you could possibly need.  I cant brag enough about them and their service.  Free delivery in the lower 48.  Like PRR I had HVAC guy open refrigerant valves and check pressures.  Did my own gas run.

Shooter, 8 ton?!?!  That will not run long enough to take the humidity out of the air!  Unless you are sandbagging and actually living in a 10,000sqft mansion like Tubenit and Jojo! :think1:

Jim :hijack1:

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Offline shooter

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Re: Lord I forgot how long it takes to build a Hoffman Deluxe Reverb
« Reply #27 on: July 14, 2017, 07:51:09 pm »
Quote
Shooter, 8 ton
yup, my friend was contracted to take down a business, I did some horse trading n got the AC unit, and NO, my house was 1400sqft, my wife n I, no contractors, built another 1500sqft on "the back-side". so 3,000sqft. and ya, she ran 10min an hour for 10yrs, then failed in a catastrophic direct lightning strike :l2:
we now have fans :laugh:  I don't like AC so when I get nagged about this time of year, my reply, the next strike might be the house, leave well enough alone :icon_biggrin:
Went Class C for efficiency

Offline bnwitt

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Re: Lord I forgot how long it takes to build a Hoffman Deluxe Reverb
« Reply #28 on: July 14, 2017, 09:13:57 pm »
Ok all you AC installers, anyone have an opinion on the bright cap?
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Offline PRR

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Re: Lord I forgot how long it takes to build a Hoffman Deluxe Reverb
« Reply #29 on: July 14, 2017, 09:41:58 pm »
We may be annoying Bnwitt.

> a free Trane 8ton AC unit

8 ton?? Mine is 1.5 ton (18,000BTU). Yeah, I know in Missouri that's a bedroom window AC. Here in coastal Maine, 80 deg is brutal hot (a dozen days a year), but the ocean damp gets miserable. Those days we start the A/C at lunch and leave it run non-stop past 4AM. It takes off a few degrees and more than a few % RH. That's part of why I want to reduce the blower speed-- it goes through so fast the air isn't much cooled and thus not de-damped as much as it could.

> opinion on the bright cap?

We added a cap to the A/C pump; not sure why.

In a Deluxe Reverb, I think it depends a LOT on the speaker and the player's style/taste. Get 100p 220p and 470p, try them all.

Offline sluckey

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Re: Lord I forgot how long it takes to build a Hoffman Deluxe Reverb
« Reply #30 on: July 14, 2017, 10:49:41 pm »
The DR was the bottom of the AB763 line. 47pF on the vib channel and no bright cap on the normal channel. All the other AB763 amps used a 120pF on a slide switch and put it on both channels. Some of the AB763s have a mid pot on the vib channel (like the SR) and some AB763s have a mid pot on both channels (like the TR).

I don't think Doug needs to update the documents. His AB763 is not a true AB763. It's his "improved" version. He showed options to include a bright cap, or not. Same with the MID pot. It's up to the builder to include the bright cap and mid control. Neither affect the board layout. I don't like the 47pF on my DR. I used a 120 and a switch.

A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO IT!

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Re: Lord I forgot how long it takes to build a Hoffman Deluxe Reverb
« Reply #31 on: July 15, 2017, 08:23:57 am »
Thanks for the reply Steve.  If I had started with a blank chassis I would have added the bright switch and 120pf cap but there just wasn't room on this predrilled one.   I've put them in on all the BFVV amps I've built and the players liked them.  This fellow plays a Stratocaster so maybe he doesn't need the 47pf.  I'm a Telecaster/Stratocaster guy myself so I might leave it off of mine too. 


PRR, you're not annoying me :smiley:   Being an old A.C. guy,  I found the exchange entertaining.
Barry
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Offline sluckey

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Re: Lord I forgot how long it takes to build a Hoffman Deluxe Reverb
« Reply #32 on: July 15, 2017, 10:07:43 am »
You may consider using a volume pot with a pull switch for the bright.
A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO IT!

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Re: Lord I forgot how long it takes to build a Hoffman Deluxe Reverb
« Reply #33 on: July 15, 2017, 11:06:20 am »
You may consider using a volume pot with a pull switch for the bright.

Now that's a great idea and I even have (4) of them in stock!  (2) for his amp and (2) for mine.  Steve, I love ya buddy.
« Last Edit: July 15, 2017, 11:14:36 am by bnwitt »
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Offline jojokeo

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Re: Lord I forgot how long it takes to build a Hoffman Deluxe Reverb
« Reply #34 on: July 15, 2017, 04:38:45 pm »
I always take the "wait n see" approach for final fine tuning when it comes to bright caps. An amp either needs them or it doesn't? no need for AC here...
« Last Edit: July 15, 2017, 06:44:27 pm by jojokeo »
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Re: Lord I forgot how long it takes to build a Hoffman Deluxe Reverb
« Reply #35 on: July 16, 2017, 08:13:51 am »
I always take the "wait n see" approach for final fine tuning when it comes to bright caps. An amp either needs them or it doesn't? no need for AC here...

What is AC?  Well with the switch in place you can have it or not so it's more versatile and is there if a particular guitar needs it.
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Re: Lord I forgot how long it takes to build a Hoffman Deluxe Reverb
« Reply #36 on: July 16, 2017, 12:47:38 pm »
Ok, all the wiring is done on Hoffman AB763 #1  Now for the critical layout to amp comparison inspection, the lamp limiter check with just the rectifier, then the voltage check with just the rectifier and then the lamp limiter with all tubes.  After that, the test phase.  Almost done with this one.  And again Steve, thanks for the pot with switch suggestion.  I don't know why I didn't think of that.  I hope it's not memory fade.  I ended up just putting one on the tremolo channel and not the normal channel since he'll probably not even use that channel.  I did have to dremel off part of the shaft on that switched pot since it was pretty long to get the knob down to the faceplate
Barry
« Last Edit: July 16, 2017, 12:51:45 pm by bnwitt »
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Curveball!
« Reply #37 on: July 17, 2017, 08:40:16 am »
Well I just ran into a curveball on this DR.  During the voltage check it kept blowing the 1 amp fuse.  I had to put in a 1.5 amp fast blo in the holder to keep it on long enough to check voltages.  With that done I'm getting 421VAC on pins 4 and 6 of the rectifier  to ground (CT) and 840VAC across both pins.  On pin 8 of the rectifier I'm getting 541VDC which of course is way too high.  This is with all tubes in, the amp power switch turned on and the standby switch on as well.  I'm using a European export model DR PT I had in stock.  A sound check had reverb but the tremolo popped when the footswitch was engaged.  So it looks like I will have to swap the PT and start over with the voltage checks.  I've followed the wiring diagram with the black and white primary wires for 120V but I guess I'll ohm out all primary leads to see if the transformer I had doesn't match the current diagram lead color wise.  I've had it in the shop for over 10 years so who knows.  The heater output is also 8VAC with the bias voltage at 61VDC when at max so everything is up.  Dang.
Barry
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Re: Lord I forgot how long it takes to build a Hoffman Deluxe Reverb
« Reply #38 on: July 17, 2017, 09:16:36 am »
Ok, confirmed.  I'm a dufus.  Obviously I have an oddball PT.  My primary wires on the PT are White, Black, Black/White, Black/Yellow, Black/Red and Orange.  I can't seem to find this wiring diagram anywhere but it's close to Doug's diagram of the Mojo 779 version 3.  The only difference is Doug's diagram is missing the orange wire.  Any ideas as to how to wire this?
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Re: Lord I forgot how long it takes to build a Hoffman Deluxe Reverb
« Reply #39 on: July 17, 2017, 09:28:13 am »
Ok, confirmed.  I'm a dufus.  Obviously I have an oddball PT.  My primary wires on the PT are White, Black, Black/White, Black/Yellow, Black/Red and Orange.  I can't seem to find this wiring diagram anywhere but it's close to Doug's diagram of the Mojo 779 version 3.  The only difference is Doug's diagram is missing the orange wire.  Any ideas as to how to wire this?
Do you have a number on it?  This would be best.


If not, put 5 volts on the rectifier winding and measure your primaries.  Use the pair closest to wall voltage, tape off others.


Does the PT have a copper shield?  If so, check the orange for continuity to the copper band.  If you get it, ground it.

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Re: Lord I forgot how long it takes to build a Hoffman Deluxe Reverb
« Reply #40 on: July 17, 2017, 12:05:08 pm »
Ed, it's stamped Fender 0990761  it does not have a copper shield
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Re: Lord I forgot how long it takes to build a Hoffman Deluxe Reverb
« Reply #41 on: July 17, 2017, 12:46:41 pm »
There's a wiring diagram here that might help:

http://www.mojotone.com/amp-parts/Transformers_1/Blackface-Deluxe-Reverb-Power-Transformer-Export-Taps

If it were me, I'd check continuity of all the primary wires to make sure that they are one winding and not two that need to be wired in series or parallel, depending. If it's all one winding, then I'd just try the black and white wires (assuming 125VAC where you live) and see what I get.
« Last Edit: July 17, 2017, 12:49:46 pm by Tony Bones »

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Re: Lord I forgot how long it takes to build a Hoffman Deluxe Reverb
« Reply #42 on: July 17, 2017, 01:17:46 pm »
Tony, thanks for the post.  I already have that diagram and in fact used it to wire the PT as it is now which is not working properly.  I've had this PT in stock for at least 10 years so I know it is one of the other versions prior to the current one which Mojo Carries.  I'm pretty sure it closely resembles the Mojo 779 version 3 Doug shows on his web site the only difference being mine has an orange wire and that diagram does not.  I'm going to disconnect everything, ohm out everything and then try wiring it like the version three diagram.  After I do that, I'll put 5VAC on the yellow secondary tap and see if I get 120VAC out of the designated primary leads.
Barry
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Re: Lord I forgot how long it takes to build a Hoffman Deluxe Reverb
« Reply #43 on: July 17, 2017, 02:15:10 pm »
Here is the Hammond Export Version which has the copper and orange wire.  AES sells these.

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Re: Lord I forgot how long it takes to build a Hoffman Deluxe Reverb
« Reply #44 on: July 17, 2017, 02:18:33 pm »
And the non export with orange.

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Re: Lord I forgot how long it takes to build a Hoffman Deluxe Reverb
« Reply #45 on: July 17, 2017, 02:49:50 pm »
Ed,
Thanks but neither one of those is even close.  I've attached a photo of the PT wires.  What I have is:

Primary= White, Black, Black/White, Black/Yellow, Black/Red, Orange

Secondary=
HT= Red, Red/Yellow(CT), Red HT
Filament= Green, Green
Rectifier heater = Yellow, Yellow
Bias= Red/blue

Like I said, exactly like Doug's version 3 MOJO 779 but with an orange wire added
« Last Edit: July 17, 2017, 03:35:19 pm by bnwitt »
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Re: Lord I forgot how long it takes to build a Hoffman Deluxe Reverb
« Reply #46 on: July 17, 2017, 03:31:48 pm »
I am sure you can figure it out.  I was just sort of saying that the orange wire is on the primary side for the shield normally.  It is just another thing to ground at your PA ground area.


I looked back at my old spec sheets, and I do have some of the old ones and couldn't find an export version with a shield from Mojo, however I know you probably order from AES sometimes.  I checked with Heybour and they make a version as well, but no orange wire for shield.  I have also gotten noise from that wire and had to move it to my earth ground spot. 


Mojo used to sell a mojo761EX that was black.  I believe it was made by New Sensor and they no longer make it.  Probably what you have.

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Update
« Reply #47 on: July 17, 2017, 04:14:49 pm »
Ok, well it appears the Mojotone 779 version 3 diagram is pretty close.  I wired the black-black/Yellow leads together and the Black/Red-Black/White leads together as shown on that diagram and with those two pairs as the hot and neutral legs I am getting voltages where they should be.  I checked the orange wire with the power on and it has 2.0VAC on it.  I'm not going to ground it unless I get hum.  The white wire which is supposed to be sealed off had 20VAC on it
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Re: Lord I forgot how long it takes to build a Hoffman Deluxe Reverb
« Reply #49 on: July 17, 2017, 08:25:49 pm »
Ed,
No, not the current 779 but an earlier version that Doug has listed as version 3 on his transformer diagram page.  It's totally different than the current one.  See the different diagrams on Doug's page:


http://el34world.com/Transformers/fentrans.htm
« Last Edit: July 17, 2017, 08:36:41 pm by bnwitt »
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