2 AB763 Deluxes Built Into 2 Hammond AO-43 Chassis's = Stereo Guitar Amp

[Toxophilite]

I want to build myself a deluxe reverb
Preferably a full deluxe reverb with two channels
But I'd like to have the reverb and tremelo built in(though I would probably build a one tube tremelo)


I have a Hammond AO-43 chassis  that has transformers that will do the job for 2 6V6s
Has anybody tried to squeeze a full deluxe or even most of one into one of these chassis?


It currently has 5,  9 pin sockets and an octal socket
I thought I could add another octal socket where there are power supply resistors. use an SS rectifier and build an external cap barn on top of the chassis in a similar position to the ones on the actual fender amps.(kind of in the middle) Also add another 9 pin socket if I was to try for a 2 channel amp


The board in these amps is only 7.5" by 2" but in a bit of hammond preamp I have(below amp in the picture) there is 2   5.75" x 2.5 inch boards which could be used instead to fit more components. THese boards have a line of eyelets down the middle as well making them more versatile


Has anybody done something like this? or squished down the topography of a fender amp significantly?
does it seem impossible?


I figure I have room for about 10.5 inches of board(i would cut one down a little) and if I use little pots(and maybe a double gang for an eq), enough room down one side for the necessary pots etc


If not does anyone have an unused deluxe reverb style chassis(just a chassis) they want to sell
 I guess I could make one too

[plexi50]

I built a Plexi on the same chassis around 2005.  Very compact. Not a lot of room. I dont think you will have enough chassis and room inside for a DR build. Here is the plexi amp i built below.
http://www.triodeamplification.com/18Watt.html

[Toxophilite]

Cool amp!
I think you are right I was doing some measuring and counting of sections on a deluxe reverb build and probably the best i could do would be a single channel with reverb , OR tremelo, but certainly not both. or a 2 channel with no reverb or tremelo
So I might try building one of each ;
-one channel with tube tremelo
-and a 2 channel with no goodies to use with my stereo setup and then use my reverb unit in front of them

I have one chassis mostly stripped out and my 2 x  5.75" boards stripped
As I have very little $$ to invest I'm doing everything as inexpensively as possible with my main expense being caps, resistors and pots bought locally.
i wish i could afford all those lovely quality Hoffman parts. they're attractively priced too, but my current finances, combined with the rising US dollar and shipping costs make it impossible right now, sadly!

[Toxophilite]

Out of curiousity did you reuse a bunch of the original hammond Gudeman Co. caps?
it kind of looks like it on one end (opposite the orange drops)

[Toxophilite]

So I'm getting going on my build
Octal sockets installed, as well as Ac power jack and fuse(not wired up


For fun I did the heaters on the tube sockets


In retrospect i think I could've had enough room for a one channel reverb and tremelo deluxe but maybe I'll make my next one like that
I still might add a socket to this one and make a two channel


I'm wondering to faciltate mounting my boards is it a problem to move the OPT closer to the PT
Or would be a bad thing?

[Toxophilite]

Like this for example (OPT reposition)
I put the choke in too
Would this layout be okay?


My other question would be regarding power supply caps
In this chassis could I get away mounting them on the terminal strips by the rectifier socket (where all the little holes are)
Or would I better off going the conventional cap barn outside the chassis route?
My eyelet board will be extending the length of the chassis and stopping just short of the terminal strip near the porcelain 6V6 sockets

[tubenit]

Here is an idea for you that should fit into that chassis size.   This is the clean channel of my current Tweed BluezMeister with one tube reverb added. 

The TBM clean with mid-boost switch and PAB (preamp boost) gives some really decent clear overdrive, IMO.

So you could use dpdt switches instead of relays and actually have a pretty versatile amp that would also take pedals well.   IF you added passive effects loop for delay, it would be even more versatile.

With respect, Tubenit

[Toxophilite]

Interesting (and thanks!)
How does that one tube reverb perform?
I'm not sure if I can use 6L6s with the transformers I currently have
Though I do have a bigger OT kicking around..

[tubenit]

You don't need 6L6's at all. Just use the 6V6's.  I simply grabbed an editable schematic and drew that up for your consideration.  And a straight up AB763  Deluxe Reverb is a great amp also.

I like the "one tube reverb" very much.  Read the first post description from ARCHIVES here:

http://el34world.com/Forum/index.php?topic=7957.0

With respect, Tubenit

[Toxophilite]

Cool
I might try that if I can rustle up a reverb transformer


How does the alternate transformer placement on my chassis look...I might just go ahead with it and maybe make a little external cap barn anywho

[sluckey]

How does the alternate transformer placement on my chassis look...I might just go ahead with it and maybe make a little external cap barn anywho

I think it looks basically OK. Post a pic of your chassis with the board placed where you think it will work.

As for cap farm, have you considered the JJ 40x20x20x20 can in that big ole cap hole?

I'm confused as to exactly what you will build. Can you refresh me? Maybe post a schematic?

EDIT... I just looked at your pic again. Consider rotating the choke 90º but in roughly the same area. Make that square hole round and put the JJ can there. Slide the OT to the left just enough to provide clearance for the cap can.

[Toxophilite]

Hmm A can cap os a good idea!
Sadly I just came back from the electronics store (which has things usable in tube amps) and it's is a good 30-40 min drive away across town. So about 1-1.5 hours drive! They have the JJ unit but it's $37 I think...whew! i just phoned to ask, too late to go back, rush hour and it would take forever!!
For kicks I hollowed out an old can cap that still has it's mounting tabs...fun! A rough job but it will fit all the electrolytics I bought
I had also already built a little cap barn out of aluminum, also a rough affair but it would do the trick if I went that route


I'll put up pictures of both those
As well as:
-A picture of the inside showing one of the short 5.5" boards I have loosely mounted and then another shot with the old board placed on top to give an idea of how long the board will be when done and how it will be positioned


Oh and I'm building a one channel AB763 Deluxe (as per your suggestion) with 6G11 tube tremelo and maaaaayyyyybbeee a one tube reverb for fun. I've added an extra socket in the old can cap hole at the preamp end just in case I want to do that.

[drew]

They have the JJ unit but it's $37 I think...whew! i just phoned to ask, too late to go back, rush hour and it would take forever!!

Wow, does this place have 2GB thumbdrives for $19.95, too?

[sluckey]

They have the JJ unit but it's $37 I think...whew!

Well, they gotta pay the rent. They probably buy from Doug for $18 and mark up 100%.   

[Toxophilite]

I'm not in the USA
I'm in Canada
I saw one online $18+  plus $16 shipping  US
That would be  $34 US which right now is around $42.45 Canadian due to the bad exchange rate
And then at least a week or two wait for the part


Hoffmans it's $18 plus $22 US shipping to Canada(not including the clamp) (that's in the flat envelope, it might have to be the box for $40)
$40 US = $50 Can  though I didn't try the USPS 1st class option which is likely cheaper
Shipping cost money, especially over the border though I think it's cheaper to ship to the States from here than visa versa
It would be a deal if I had a bunch of cash and could afford a lot of parts
The store's price might've been actually around $33 plus tax which is more like $35 CAN
Their prices for everything else are pretty reasonable actually
And this store and another right next to it are pretty well the only game in town for high voltage components
The store close to me is all Computer stuff, some high voltage caps but veryhigh prices.


Either way it's pricey
soo
I made an in-an-old-can-multi unit for kicks
I can always swap it out later if I feel I need to
It seems to be working


Here's a question
THis is going to be a one channel unit with a one tube tremelo...and maybe a one tube reverb


The non reverb AB763 deluxe only has 4 x 16mfd caps whilst the deluxe reverb has 5 with 2 in front of the standby switch


If I'm not having the extra channel and no reverb do i need the extra cap prior to the standby switch??

[sluckey]

Those two caps prior to the STBY switch on the DR are in parallel. One 32µF cap (or 40) could be used instead, bringing the count back to 4 caps. Really, that JJ can is perfect for a DR build in a space restricted chassis.

I didn't realize you were in Canada. Send a pm to tubegeek. He's up there too. He does a lot of amp work. Bet he ain't paying $37 for a JJ 40x20x20x20 can. He can probably give you some affordable alternatives.

[Toxophilite]

Cool!
THanks
Maybe I'll try that out

[Toxophilite]

IS it YVR tubegeek?
or just tubegeek?
THere seems to be 2


YVR is the Vancouver airport code


Unless they were in Vancouver area(lower mainland) shipping would probably be a problem here too
It generally costs more to ship within Canada than it does to ship to anywhere in the States and even overseas, like Japan etc..crazy!

[Toxophilite]

Oh and my apologies to Hoffmans
1st class shipping is about $9 US
so really $27 US total (not including clamp) about $34 US

[Toxophilite]

So Moving right along
I have my boards stuffed , but not screwed down yet. They're on brass standoffs that I adapted from an old reel to reel


Also nothing is hooked up so there are wires everywhere. I left most of the wires on the original 9 pin sockets as it's decent wire and I'll re-use some of them where possible


 My pots aren't installed yet though I have the points on the chassis marked


My faux can cap setup works (I tested it and NO SMOKE!) though I had to add a 10uf -500vdc as one of the little guys inside the cab lost it's positive lead(yay!) so it's in the chassis next to the PT


I have a couple questions:


- For running the B+ to the appropriate points I was thinking of routing the wires underneath the boards between the eyelets (and maybe assuring the stay between them) from the terminal strip closest to the PT) . How does that sound?
( I was also considering some sort of little conduit they could run through under the boards (a section of old aluminum arrow perhaps) Maybe not necessary)


- The secondary wires of the OT come out of the chassis near where the tremelo pots will be (closer to the 'front' of the amp), .If I'm going to have the speaker jack at the back of the chassis (the same side as the power switches etc) Can I run the wires above the board to reach it?  If not what would be a better alternative?




Thanks!

[sluckey]

This is looking like an amp! I think it's all gonna fit. How did you like cleaning up those cone boards? 

For running the B+ to the appropriate points I was thinking of routing the wires underneath the boards between the eyelets (and maybe assuring the stay between them) from the terminal strip closest to the PT) . How does that sound?
( I was also considering some sort of little conduit they could run through under the boards (a section of old aluminum arrow perhaps) Maybe not necessary)

Under the board is fine. I would not bother with conduit.

The secondary wires of the OT come out of the chassis near where the tremelo pots will be (closer to the 'front' of the amp), .If I'm going to have the speaker jack at the back of the chassis (the same side as the power switches etc) Can I run the wires above the board to reach it?  If not what would be a better alternative?

I would run them under the board. Route straight from the grommet to halfway between the power tubes all the way to the back. Then turn left or right to get to where the jack will be. I like to put the jack on the back but located between the power tubes if possible.

[Toxophilite]

Thanks
It took me a little struggling to clean the cone boards .initially I stupidly removed them from the chassis...That was really awkward so I put then back in, stuck the soldering iron into an eyelet . waited and the yanked everything out, down one side, then the other, Went okay after that but did take a little time! I have piles of old resistors and wire though
I can see the advantage of the eyelet/cone/turret board when mass producing amps, One could easily have someone just stuffing boards.
Also they're easier to maintain (replace parts etc.) I'm a happy convert


 I'll get to work on that stuff and install some pots too


Thanks again!

[Toxophilite]

One more question if I may;


Should i do anything to keep the OPT secondary wires from the B+ wires where they cross them under the board??

[sluckey]

Should i do anything to keep the OPT secondary wires from the B+ wires where they cross them under the board??

no

[Toxophilite]

Aiiiee it Lives!!!!


Mostly!
I have the amp together and seemingly basically working well
I haven't really checked it out as it's late
Doesn't seem to be noisy
all the controls work....except for the tremelo, which I can hear working(and the controls effect the slight tremelo-y seound I hear) but it doesn't effect the guitar sound
I think I have to pop open my previous deluxe light with 6G11 tremelo to see how the guitar signal is sent to the tremelo


I had some funny bloopers, forgot to hook up the preamp to the phase splitter! (because of the tremelo circuit in between)
I forgot to hook up the negative feedback
and best of all , the one that stupified me the most!!
I forgot to ground the &%^$*%^*&^ cathodes on the 6V6 sockets! oh yeah!

One thing I'd like to get an opinion on;
I ran the B+ for the power tubes (B) and the tremelo 12AX7 (A) down the back of the chassis, it seemed to make sense at the time.
Would that be a potential problem?
I can move them to where the others are
As discussed previously the other two B+ feeds (C + D) are down the middle of the board

My B+ is still a little high all around
And I have to spend some time straightening out wires and cleaning things up a little
but it's time to hit the hay
More trouble shooting tomorrow
Here it is in in all it's unlikely glory (note the oops hole in the input area! some hole patching has to be done on the chassis overall)
THanks

[sluckey]

Wow! Lot of progress! You must be working non stop. Looks good.

all the controls work....except for the tremelo

Are you using Doug's bias vary trem? If so, it may work once the bias is set.

I ran the B+ for the power tubes (B) and the tremelo 12AX7 (A) down the back of the chassis, it seemed to make sense at the time.

That's fine.

My B+ is still a little high all around

I bet that if you set the bias to run the 6V6s at 25mA your B+ will settle in at about 400v. That's very good territory for a Deluxe AB763.

[tubenit]

Very impressive conversion!  Great job.  Thanks for sharing the photos.

With respect, Tubenit

[Toxophilite]

THanks
I have been toiling away at it


The tremelo circuit I'm using is the 6G11 Vibrolux circuit which looks to be pretty close to what Doug uses
 Right now I have a non adjustable Princeton AA964 bias steal
Right now I'm getting -35.5 coming off the bias circuit


So I think I have to pop open my other deluxe with the same setup and see what I did..It has a pot to adjust the bias


I had about 382 vdc B+ at the 'B' point with the 5U4gb and was having to up the resistors before the C and D point as my B+ downstream was too high (I had 20K between B and C!)


To get the initial voltage a little higher I tried my SS rectifier which gave me 420 at B but now my voltages at B+C were too high again


I can't seem to measure the ma at the 6V6. Do I do it across the 1 ohm resistors on the cathodes??

[Toxophilite]

Well
It was useful opening up my electrohome deluxe light with tremelo conversion...I noticed a resistor in the tremelo circuit I forgot to tie to ground..hey presto! lovely tremelo!


So that's solved


That amp used a 47 uf electrolytic, 22k cap and a 50k pot in the bias circuit


I'm curious about the B+ and measuring the ma bias at the 6V6 tubes

[Willabe]

I can't seem to measure the ma at the 6V6. Do I do it across the 1 ohm resistors on the cathodes??

Yes.

But set your meter for volts, 1mV = 1mA.


                      Brad     

[Toxophilite]

THanks!
I get about 26 ma and that's with a B+ at the 6V6s of 375vdc (with the 5U4Gb rectifier)


With the SS rectifier in and 420 vdc at the 6V6s I get around 36ma


This is with the bias steal that I have that provides -35.5 volts


Soo
Would I be better off at the lower voltage  and 25ma and leave my bias setup as is?


OR should go for the more conventional deluxe voltage of 420volts , install an adjustable bias and adjust it back down to around 25?


Tremelo is working, amp is working I'm just tweaking now adn would like to know the most desirable scenario
i like to play nice and clean!


Also curiously at two plates of the preamp 12AX7 (V1) I get 200vdc on pin 1 and around 185 at pin 6..all else being the same (plate resistors, cathode followers etc)

[Toxophilite]

Well a few things sorted quite satisfactorily
-Replaced the blown cap which was I believe a result of the 10uf (in parallel with the 22us (1st filter stage))
losing it's ground lead(broken!) I can't be sure the rectifier was bad or was killed by the cap blowing
-Put in a better condition 5U4gb rectifier
-Added the adjustable bias control
-set it to 25ma ..all voltages very close now
And best of all
- getting rid of a little hum by isolating the input jack and running it's own ground to the main signal ground..MAGIC!
lovely silent Deluxe tremelo (no verb)

[Toxophilite]

I'm quite impressed with this amp..I barely can tell it's on! and it sounds lovely like a little deluxe should!


I'd like to thank all those who helped so generously and particularly S. Luckey who pointed me in the direction of building a 6V6 deluxe in this chassis having already done the groundwork of testing the capabilities of the transformers.
Otherwise I wouldn't have considered it


I'd recommend it as a good platform for AB763 deluxe light build.
One channel with no goodies if you just use the original board
If you have a longer board(like a Hoffman board)
Then a 2 channel amp with no goodies
or a one channel one like mine with tremelo, or reverb (but probably not both)


I have another one of these chassis that will be the second side of my compact stereo rig
It will be a 2 channel model  of the same (no effects)
I have to find or buy a choke though as I used the one on that chassis for my previous deluxe build!

[Toxophilite]

Hey to stop my standby switch from making a giant pop through my speaker do I just run a large value cap say .1 or more to ground from the choke side of the switch??

[Toxophilite]

For the purposes my the intended use I've added a line out to my deluxe A0-43 (I'll call it that for now)



I followed the silverfaced fender model of putting it at the speaker output but I used a 4.7 resistor from the speaker hot wire and a 150 ohm resistor to ground, to set the impedance (I got this from the postings of my previous deluxe AB763 build (thanks))
This works quite well and the tremelo comes through as well which is useful


My question is:


Can I put a pot (say 10K maybe) instead of the 4.7K resistor and use it as mixing pot for the amount of signal I send from the line out?

[shooter]

I didn't look at how your line out is set up, I used the one attached that uses a 1k pot, I didn't record my voltage but seems like I could go from about .5vac to about 2vac. anyway, FWIW

[Toxophilite]

That's a cool looking line out. It uses an isolation transformer, yes?
I'm just going to try alligator clipping in a a 10K pot and see what happens for kicks

Here's a question for S. Luckey if I may

I was re-reading the post where you suggested using 6V6s with this hammond chassis after having done a lot of testing
You weren't confident that trying 6L6s in this amp would be a good thing
Is it primarily the output transformer that makes this a problem?
I was just speculating for fun about it, I know people sometimes run their deluxe's with 6L6s at 35ma and get around 30 watts out of them.
I do realize though that these transformers aren't deluxe transformers

I was going to build another of these with another AO-43 shassis and was wondering if the addition of a more skookum OT would enable a more Ab763 vibrolux type conversion if one were so inclined.

[sluckey]

I think the PT is big enough for 6L6s but the OT is a little small and is the wrong impedance. Running a 4Ω speaker load would reflect the correct impedance for a pair of 6L6s but the OT is still a little small. I'd get a beefier OT.

[Toxophilite]

THanks
i was monkeying around with 6L6s just for fun(actually sovtek 5881/6L6WGC)
and it certainly was louder and cleaner but had a mid focus I wasn't too keen on
Fun to try though


A question regarding tremelo
the circuit I'm using is from the 6G11
which uses -45 (with 6L6s)


the AB763 deluxe uses a -35 bias


I have the adjustable bias ala Hoffmans unit


When I bias my amp to 25ma on the 6V6 cathodes I have -39-40 at the tremelo depth pot and the grids of the 6V6s


Is this bad?
Should I tweak my bias circuit?


here's a couple pictures of the pretty well finished unit with jewel light knobs etc
On the back there's a speaker out, a SF style line out (with a 10K pot and a 2.2K resistor in series to adjust the strength of the signal) and the vibrato footswitch jack
I removed the standby switch
Still have to cover a couple of holes


(the little unit sitting on deck to the right is an SS rectifier with 110ohm dropping resistor built in to simulate a 5AR4, I might end up using it but it will require a little more tweaking of power supply resistors)

[Toxophilite]

Here's what I intend to do with this and the other amp I'm starting to build ( 2 channel AB763 deluxe)


This is a cabinet I originally built with the intention of using it with a Baldwin rogan stereo amp, identical to the one I showed in my post about transformers. However, I knew very little at that time and despite getting it to work (with all the preamp controls on a separate chassis) It made a lot of noise.


So I've had the cabinet kicking around, It's about 13.5" deep by 22:" wide and 18.5' tall
Made of 3/8" baltic birch ply (including baffles) with internal bracing
Each cab has a little back panel (not shown)
It has a baffle and grill cloth on the front and back and splits into two 6.75" deep cabinets
It was originally intended for a 12" speaker in each cab (JBL D123)
But I've been toying with the idea of 2 x10" in the main cab (that's why one has a ply baffle tacked into it right now)

It's for having stereo sound and running my space echo stereo in a loud but portable package
I think I'm leaning towards having the amps on the bottom with a cutout for the controls on the front as hanging them upside down is a little more problematic (and installing lot's of tube holders)
Also a little less stable


This is a setup I've wanted for years, small but big and spacious sounding


The second amp is almost mostly gutted and ready to go

[TIMBO]

Great work. 
I have two Hammond chassis awaiting transformation.
One is from a Hammond Everett series and the other is a Hammond AO-63, this has two amplifiers in one chassis. The main amp has a pair 7591 power tubes and the other has pair of 6GW8.
The 6GW8s are the amplifier for the reverb. It also has the vibrato as well I think.
I will probably make this a combo. Thanks

[Toxophilite]

A friend of mine and I picked up one of those AO-63 amps fro him to make a bassman out of , I scoffed the extra OPT which is the same as that used in the AO-43
He gutted it quite nicely in preparation, but in the summer he was working on it on his deck and left it out upside down one eve when it decided to rain(it does that here)
It's been drying out for about 8 months now but he hasn't got back to it yet
Looked like a good platform though. HUGE PT

[Toxophilite]

Getting going on the second Chassis
Gutted and cleaned up
OPT removed for repositioning
power jack, switch and fuse installed, pilot light wired in but not installed
Broke down and bought the JJ can Cap locally for $32.50 CAN! + the #$$%% clamp
It was worth it, very compact, clean , easy to install, looks good too
It'll be half the mess of wires
I'm going to buy one for the 1st amp


I'm trying out a pair of 6CM6 tubes that I have on this build
They are 6V6GTs in a 9 pin bottle (like an EL84 in size) and cheap like borsch, what's not to like?
No changing of power tube sockets, just twisting heater wires
Same sound and power, very cool! and it makes this build a bit of an experiment, fun


Started the heater wires but time to hit the hay

[sluckey]

You are becoming the go-to man for these AO-43 conversions.   

[Toxophilite]

  Funny!
I just have the bit between my teeth!
I've wanted two deluxe's for years but have never been able to afford them
This way I can! and it's thanks to all the help I've been given.

[sluckey]

I just have the bit between my teeth!

Oh, I totally get it! Haven't heard that phrase in a long time. But it reminded me of a skittish red mare I had as a boy. This horse constantly looked for boogers while riding. You never knew what a booger was until it was too late. Might be a paper bag, beer can, or just an unusual stump. She would take the bit, jump sideways and break into a hard gallop. All you could do was hang on for the ride!

Just be careful that you don't get totally caught up in AB763 Deluxes. I know one member (won't mention names ) that got locked in on Plexis. For a couple years he converted everything he could get his hands on into a Plexi. I think he's finally cured of that addiction.

Since you like the sound of the AB763 you may want to consider some of the 6V6 based Ampegs. They have a very nice clean sound similar to the AB763, but the sound is also much warmer.

[Toxophilite]

Hilarious!
I was going to say I could smell the stable!
I was just trail riding yesterday. A friend has a couple of horses( Both Stallions/Geldings,not sure... )),a white Arab and Gruella, I get to ride the ornery teenage one(The Gruella)!
He was really picking up the pace on the home stretch back to the stable.

I'll look into those ampegs
Right now I'm just trying to finally use these cabinets I made 3-4 years back for a stereo amp setup

[Toxophilite]

Don't you love it when you drill all the 1/8" pilot holes for all the pots and inputs and then you have a 4th and 5th look at your planning and realize you need to move them all!!!!
So much for that pristine front of the amp!
Got the standoffs for the boards mounted and the boards themselves cut down to size, pilot light mounted

[Toxophilite]

A question for those who have made AO-43 based amps


The OPT  secondaries originally have the green to ground and the BLk to positive


I unthinkingly hooked it up the other way as it's DC and Blk is generally ground


Does it matter?? It works fine I'm just wondering about phase in conjunction with other amps etc etc


Hooking up the 9 pin 6CM6 sockets, going to require some head scratching to make sure I get it all right

[sluckey]

Does it matter??

Since your project uses NFB from the OT secondary, yes, it matters. Just be ready to swap the secondary leads --OR-- the OT primary plate leads if you have NFB issues.