AO-43 Hammond

[dude]

What's the most you guys would pay for this chassis ( Hammond AO-43)  with original tubes, all working?


al

[sluckey]

Search on eBay. Then select show sold listings only.

You don't want to know what I was paying for these just two years ago!

[Apexelectric]

Bought one not too long ago without tubes for 80 delivered. I think I might have paid too much.

[dude]

Looked at flea bay sold Hammond AO-43's, last six months average price was about $125 with shipping, most with no tubes. I paid $125 with shipping, probably a little too much...? But came with all the tubes, had old stock tesla EL84 and two old stock 12Ax7, figured they had to worth $25 at least.


Here's a pic: https://i.ebayimg.com/images/g/9ysAAOSwp-RabQCs/s-l1600.jpg


Just noticed the old Tesla's are marked EL8055's...?  But don't all these chassis come with EL84's or equivalents? Was the gold paint stock or did the guy spray it...?


OK, make me feel good, Sluckey give it to me, what were you getting them for.... ? 

[sluckey]

I saw your amp listing on eBay. He even painted the plastic molex connectors! The original AO-43 had 6BQ5s (should be able to see the tube type stamped on the chassis unless that paint is too thick). All original tubes are branded Hammond. Chassis was natural steel color (plated, not painted). OT was silver (some kind of plating). PT was painted black. I've never heard of an EL-8055 tube. Beware if those tubes are EL-805 because they are not pin compatible.

I bought two AO-39s three AO-43s, two AO-44s, and one AO63. Most I ever paid was $40 shipped. I sold an AO-43 to a forum member last year for $50 + shipping.

An unmolested AO-43 looks like this...

 

[dude]

Kind of weird, the guy plugged in the amp to take pictures, all tubes lite up, I would think no one fooled around with the innards?   only   Sure looks like an AO-43.

Closer look those Tubes are EL8035, not 8055...? Can't find any cross reference...? I know the old stock El84 tesla's were great tubes, was thinking about pulling them in my 18 watt TMB but are they a version of an EL84..? Who knows Russia has put some crazy numbers on their tubes...?


Update: No such tube made EL8035, must be EL84 on back of tube....?

 

If the tubes are EL-805's and their lighting up, then were the sockets were rewired...?


Anyway I planned on drilling out the "EL8035's" (or whatever they ar) for 6V6's and make a 6V6 Plexi. Probably get that gold paint off too, bugs me. Live and learn.


There's a  AO-29 for $90 on ebay, now.

[drew]

Looks like EL803S to me.
https://www.benl.ebay.be/itm/Tesla-EL803S-gepruft-tested-gut-EL-803-s-NOS-tube-/141263371894

[dude]

Drew, your right.


 https://tubes-store.com/product_info.php?products_id=378


Conversion chart says not compatible with EL84, unless two pins are shorted and they say "(don't know which pins)" Do not use in place of EL84..?


Can't figure why the tubes are in this amp AO-43 and picture shows chassis plugged and and all tubes lit


Is this a European version of AO 43...?

[sluckey]

Can't figure why the tubes are in this amp AO-43 and picture shows chassis plugged and and all tubes lit

Because the filament pins are the same. I'm not aware of a European version of the AO-43.

You should be able to look at the wiring and tell if someone has rewired the sockets to accept those tubes. If you can't tell, post some pics and maybe we can tell.

[dude]

Thanks Sluckey, will do.


I just hope all the iron is AO-43 specs.


So, most likely either someone rewired the sockets to take EL803s or the guy just put any tube in there to look good for a sale. I surely can't use those tubes as planned in my 18 watt TMB, probably garbage.


Live and learn, the guy "accepts no returns" that should have been a clue..? 10 to 1, he or someone else just put what he had in those sockets and it's a Hammond AO-43. Since I'm changing to 6V6 and just using the iron, I should be ok. Need to get that James Bond paint off too, bugs me. Half the sellers on ebay do anything for a sale.


I'll check it all out, when I get it and post.


Here are the specs on that tube, can someone decipher   https://frank.pocnet.net/sheets/183/e/EL803S.pdf


Thanks,
al

[sluckey]

Give me the numbers on the transformers and I'll tell you if they are correct.

[PRR]

EL803S is *not* a replacement for EL84/6BQ5. Related, but not the same.

You have two sons. One plays football, fairly stocky. The other is a gymnast, slim.

EL803S is a video amp. Similar cathode, tighter grid, smaller plate. More gain than grunt. In a 6BQ5 audio power amp, it will idle cold, then melt when beat upon.

It IS close-enough to light up for pictures, no mods. Because G2 moved, it is likely to sit with plate circuit stone-cold.

While we "could" design an audio amp around EL803S, the iron you have favors the readily available EL84.

[dude]

I received this Gold-finger AO-43 chassis, live and learn. Guy bent the tabs on the end of chassis to fit the shipping box .


Something's weird about this chassis, all the tubes mostly old Russian tubes, the 5u4 socket had a 5u3C (russian substitute?) The EL84 sockets had EL803S in there place, the wiring on those sockets looks original..? Is this a European version?


The EL803 is an equivalent to 6CK6/EL83... Here is the some info I found on substituing an EL83 for a EL84: https://www.18watt.com/viewtopic.php?t=21593&start=15


Here is a substitution chart on the on the EL83/6CK6:  http://4tubes.com/DATASHEETS/CATALOGS/TUBE-EQUIVALENTS/Tube%20Equivalents%20List.pdf


All I can see is pin 8, not used in EL84s but in EL83s is a screen or is internally some kind of shield...?


I did find info that an EL803S is substitute for a EL83 or 6CK6. So I believe an EL803S is a substitute for an EL83/6CK6? http://tubedata.milbert.com/sheets/128/e/EL803S.pdf


Just curious as in the 18 watt link above, some well know guys on 18 watt said a simple wire change could be made to an EL84 socket to run a EL83 but the info on the change is gone...? Just wondering if I grounded pin 8, could these EL83s/ EL803S in an EL84 socket as stated above in tha tlink?


The Gold-finger chassis PT, OT and EL84 sockets are below:


PT: O-24157-1     Chassis has all the correct tube locations printed next to sockets, none of the tubes were marked Hammond, but most
   549-6745         were Russian, 12AX7s were from Canada, the 12BH7A was a GE

[dude]

Full pic of chassis

[sluckey]

There is no European version. PT and OT transformers are original AO-43 transformers.

Why even mess with an oddball Russian tube? You'll have to rewire the screen grid and externally connect the suppressor grid to cathode. EL84s are very common and cheap too.

[dude]

OK, thanks. Just read that old 18 watt tread and though...? I'll just sell them on ebay, your right all my el84 amps sound great to my ears.


I want to order Doug'd 6V6 plexi bd. but it's too wide for the A0-43 chassis. You think if I ordered it and in special comments just ask for a different dimension like 8" x 2 1/2", his 3.12" is too wide, length is ok but a little longer is best?


Also, I want the flexibility of being able to use EL34s and 6L6s, (with the correct biasing, etc. and changes needed, maybe switches) I also want to use a rectifier tube to lower the voltages a tag with 6V6s, could use a SS plug in for 6L6 and EL34s.
Anyway, there isn't enough space if I drill out those el84 sockets, maybe 6V6s would work in a head configuration but not the others. Do you think if I put a plate over the holes and drill new holes, wit henough space (would be tight but looks doable) with a step drill bit, would I have a wandering problem..?   Don't Have a punch.


What would you do in this case, (don't say get a new chassis,  ) ../


thanks,
al

[sluckey]

I think the first thing you need to do is zero in on what circuit you want. Then decide which tubes. I would not use EL34s because of the high filament current requirement. I probably would not use 6L6s either. But I know for a fact that those transformers will work very well in a 6973 or 6V6 based amp. I used that iron in my Plexi6V6 and also in my Supro S-6424.

Hoffman will not rip a narrow board for you. All his boards will always be 3-1/8" wide. If you must reuse that chassis, then consider reusing the original cone board too. Just clean it up and get all the solder out of the cones and then design the layout based on that board. Search for posts by Toxophilite. He has built a couple AB763s on the AO-43 chassis. Probably some good ideas.

I think putting a plate on top of that chassis and redrilling holes is a lot of work and ain't gonna be very pretty, so I'm gonna say it anyhow... Get a new chassis and use only the iron from that AO-43. There, I feel better. 

[dude]

Well thanks for a the advice, I can probably use the original eyelet bd, onced clean, even for a 6V6 plexi. But I agree on the attaching a plate and drill out for bigger tubes, problems.


So, I'll stick with 6v6 and a plexi design either Hoffman's or huss's, both very close. But will check out your other suggestions, thanks
 

[Toxophilite]

I have put a plate on top of a AO-29 (harmonilux reverb, later converted to a straight vibrolux reverb) and an AO-43c(deluxe reverb converted into a vibrolux reverb) and drilled new holes (I used aluminium from an old organ chassis because it was free!) but as S.Luckey says it's labour intensive and not as neat as a purpose made chassis. It can certainly work fine though, but you have to design your amp around the chassis size and limitations. I like that sort of thing but it's not for everyone.

[sluckey]

If a 6V6plexi is your goal, that's very doable in that chassis using that cone board.

I've cleaned two of those cone boards. This is what works for me... Take the board outside to a table. Lay down a bunch of newspaper or other disposable covering. Use your soldering iron to heat up the cones and immediately blow the solder out with a real shop air compressor. Makes a mess but you end up with clean cones that can be used just as they were originally intended.

I actually like the cones better than eyelets because you just poke the component leads in and the cone will spread to accommodate 4 or 5 leads. Spring tension holds the leads together for good mechanical contact. Then fill the cone with solder and cut off the excess leads protruding from the small end of the cone.

[dude]

I have a shop with compressor, probably don’t even have to tin the “cones”. I thought they were eyelets. So, drilling those two el84 sockets, fit 6v6s, the bigger tubes in a head configuration they won’t be too close? I want to use a rectifier tube.

[dude]

OK, 6V6 plexi it is but I still want to try 6L6s and EL34, if the PT gets hot well I'll stick with 6V6's.
That hammond AO-43 PT is beefty, handled Six tubes and a 5U4, I don't plan on using a 5U4 but maybe 5V4 or 5AR4.


Anyway, I took pics of my AO-43 chassis, took the two EL84 sockets out, put a steel plate over the holes, and spaced two 6L6's (fat GE's) and a big 5U4 rectifier tubes in the spots I will redrill, redrilling only the 6L6 sockets.


I will use a top and bottom plate, fasten "very tight" before drilling the new holes (clamps). The the two plates should keep the step-bit from wandering. I will use a drill press, and secure the chassis tight to the drill press base. And go slow.


Anyway, is there enough room to dissipate heat from the tubes, this will be a head cab so tubes will sit upright.


al

[sluckey]

I think you'll be fine with 6V6s. And I don't think you'll have to worry about drill bit wandering with the method you described. In fact, you can just use a single plate if it is thicker than the original chassis. Don't forget, your step bit may only drill thru 1/8" before moving to the next step.

I'm gonna say it again... $42 will buy a nice 17.5 x 6.5 x 2.5 aluminum chassis like you may have seen on some of my projects. That will give you plenty of breathing room. In fact, I put my 6V6Plexi in a 12.5 x 6.5 x 2.5 $38 chassis. With some planning it fit very well...

[dude]

I know your work is flawless, neat, clean builds, everyone of them and I'm working on a build like that now.
Just that I love the challenge to do the impossible, I know my work is not the neatest but I'm working on that. 
I'm over cautious and can get anal at times, and like to do conversions as cheap as possible but with quality parts.


I do these cheaper conversions so I can sell them to player friends who are always broke, for cheap. I enjoy the look on
their faces when they play my conversions. I can sell them for $250 to $300 with a head cab.
For me 6V6's are fine, plenty of power and it can be miked. But my kids friends are players who play out. The guy I'm making this for might need 45 watts and a pair of EL34s at some gigs without a house PA.


I appreciate your advice , S. Luckey for always guiding me and answering all my questions, always a helping hand to all here who post here.


I'm having my Saturday night 5 O'clock drink on you, cheers !      

[sluckey]

Hey, I totally get the "challenge" thing. I'm having a beer with you right now! Cheers to you too.

[dude]

I'm ready to drill, but had another thought. Rather than attaching a 16 gauge steel plate inside, and or outside. Using a drill press as mentioned in aboves posts, I now am thinking of cutting the chassis's old EL84 holes out. Just cut a rectangle piece of the chassis out, old holes and all. Then cut a slightly bigger piece of 16 gauge steel to cover the cut rectangle hole. This way I would be drilling 6V6 socket holes in a solid piece of 16 gauge steel, I'd attach the new plate with the holes evenly spaced between rectifier tube and PI 12Ax7 with stainless steel ribbits.


Might be a cleaner job, and none of the old holes would be, half cut...


Thoughts, I know I'm getting anal here, but you only get one chance to "not hack up" your conversion.   


al

[Toxophilite]

ribbit ribbit!


'stainless steel ribbits'



That sounds good if you want to space your tubes out more . Also in mounting tube sockets it's good to only have one layer.
Are you relocating your OT and choke too. I would say that at least the choke is pretty poorly located for power supply choke usage.

[dude]

ribbit ribbit!

'stainless steel ribbits'

That's right ribbit's, haven't you heard of that Rabbit...


OT same place as AO43 had it but choke over to power supply side, most likely next to PT, upright or inside chassis wall.
OK, I won't use stainless steel "ribbits", although I love ribbits they eat carrots , I'll use stainless steel rivets instead,   


Where would you put the OT?


al

[Toxophilite]

Probably fine where it is . I think I shifted mine slightly towards the PT.


here's the link towards my first two builds
http://el34world.com/Forum/index.php?topic=18265.msg186291#msg186291

They turned out well and i use them both yet the grounding scheme and I think the use of can caps gave them a ground loop hum when used with my space echo.
 I get around that by using adapters that lift the ground and they get their ground from the space echo so i don't die!


On the AB763 builds I've done since I used the method where your power and PA grounds connects to a star ground right by the PT and then you have a ground rail running along side your board (also connected to the star ground) which all the other B+ nodes connect to.
The B+ is kind of arranged the same way with dropping resistors and filter caps for each node being located next to the area they are providing power for. Somewhere there's a link to this method, might be on the Hoffman's site. I can't quite remember , maybe someone here can help wit that. It seems to work really well and makes sense .

[dude]

I've grounded like you mentioned but ran a 12 gauge bare copper wire from close to that Power side star ground, floating all the way to the inputs and then grounded there. The copper wire along the way would pick up various grounds down the wire, ending with the inputs as mentioned. Never had a problem or hum. Sometimes I don't use the copper wire, and ground all the E caps and PT to the Star Ground next to PT and all the way at the other end a ground for the inputs and preamp. Ground loop..?


al

[Toxophilite]

Yeah I used a heavier bare copper wire. That's just how I did it.

[DummyLoad]

EL803S is *not* a replacement for EL84/6BQ5. Related, but not the same.

You have two sons. One plays football, fairly stocky. The other is a gymnast, slim.

EL803S is a video amp. Similar cathode, tighter grid, smaller plate. More gain than grunt. In a 6BQ5 audio power amp, it will idle cold, then melt when beat upon.

It IS close-enough to light up for pictures, no mods. Because G2 moved, it is likely to sit with plate circuit stone-cold.

While we "could" design an audio amp around EL803S, the iron you have favors the readily available EL84.

seems to be "electrically" similar to the US 6CL6 and variants.


--pete

[dude]

Yeah I used a heavier bare copper wire. That's just how I did it.

.        I read your Deluxe AO43 link you posted, that cap can is in a square hole...? I’m probably going with 40,20,20,20. How will I change that square hole to bigger, round hole to fix the JJ can

[Toxophilite]

grind it out, dremel it out, or use a really rough round metal file. A big chainsaw file works well. That and some elbow grease!

[dude]

Maybe a jigsaw with metal bit, my step drill will bounce around and probably ruin the bit.


What about putting the can down by the end opposite the PT, far away from power supply but there's a big cap can hole already there?  Problem running the HV wire to PT side...?

[Toxophilite]

I didn't put mine there because the preamp was at that end and it seemed counter intuitive to put it far away from where it mostly needs to be.
Aren't you cutting out a square of metal to accommodate your re-drilling of the power tube holes??
If so make the hole/plate bigger and recut the can cap hole too.

My self I just enlarged the existing hole, You can get it started by taking an 1/8" drill bit and drilling around the edge you want to enlarge and then file/cut it out. Many ways to do it.

That's my two bits

[dude]

Here's the moved and enlarged sockets, cut out the old chassis 9 pin sockets (rectangle cut).
Added a 16 gauge stainless steel plate, riveted over cut and drill 6V6 sockets in the plate.


You'll see one socket mounted like the others (from under the chassis) but the screws holding the sockets hit the base of the 6V6s and prevents them from going down all the way down but tight enough. The other socket, mounted above the chassis is raised and the tubes go all the way in the socket but have to use a small washer.
Not sure which way to mount the sockets, or whether to get different sockets that mount under the chassis but have a higher base above the chassis...? Wonder if arcing comes into play? 


Took a good two hours, but now 6L6s (fat GE's) are 1/4" apart, EL34 even further. Just wanted the option to try 6L6's and El34's. Anyone know the specs on that Hammond AO43 PT? Can't seem to find much info. 


I'll take pictures as I go and when done post them in a new post.


al   

[RWood]

Looking good, Al.

I've heard of folks using 6L6s but I would be wary of EL34s. Those L100 amps powered two other small chassis, I think the percussion and maybe the vibrato, each with 2 - 3 small signal tubes.

I've never seen a current ratings for the PT though.

[Toxophilite]

6L6s do seem to work
However you don't get much extra juice out of them unless you install a bigger OT which is what I did with mine