Building the H-O-Lux

[Steiner]

Yea Baby! Go H go.

[H]

I got a swift response from ClassicTone yesterday evening which set me straight on the PT wiring. There's about 15 minutes work there and I have a capacitor coming today which needs adding to the board. I also need to make up the RCA leads to the reverb pan and the speaker cable.

 

Finally, I need to buy a footswitch but I can just short out a pair of RCA plugs while I'm waiting for it to turn up.

 

So, not a lot to do before I can break out the lightbulb limiter and the multimeter

 

This is where I'd like to ask anyone on the forum who has experience debugging circuits to chip in: what is your standard sequence to test a circuit of this complexity? I have a multimeter, a bias testing plug and the 1960s AA964 layout showing voltages at given points.

 

My plan is as follows (each step assumes the previous checked out OK):

 

- attach the lightbulb limiter and power up with no tubes.

- test the voltage into the rectifier socket.

- power off, turn the bias pot and all volume, etc, pots to the minimum value and add the rectifier tube.

- power up and test the rectifier voltages.

- test the power and pre-amp filament voltage.

- power off and add the power tubes.

- power up and test the rectifier voltages again. Then check the power tube voltages and working systematically down toward V1, check the board voltages. Switch on the reverb and recheck relevant areas of the board. Same for the vibrato.

- bias the power tubes

- plug a guitar into channel one, raise the volume and check for oscillation and other interference in the output.

- check the range of the treble and bass pots and the bright switch.

Same for channel two, additionally engaging the reverb and then the vibrato.

 

Have I missed anything? Would you do things differently?

 

Ah, I missed a few steps!

- rock out and rattle the windows.

- take pics and post them here.

- make clips and post them here.

[DetroitBlues]

don't forget stage dive...

[big bob]

this is what I did with the champ....

INSTALLING TUBES AND

TESTING

Follow these instructions very carefully!

A note about voltage readings before we begin: There are many original

Fender factory schematics available on the internet that have voltage

pinouts. Be aware that Fender was notorious for publishing inaccurate

voltages. If you see an original Fender schematic for the 5F1 circuit, it

will tell you that the B+ voltage should be 340VDC. This is about 85

volts less than what it should be. So do not be alarmed if your voltages

do not match the Fender schematic.

Now, for the moment of truth. Firing up your amp for the first time is

always an exhilarating and nerve racking experience, no matter how

many amps you've built, but don't be scared. As long as you follow

proper safety precautions, you won't have anything to worry about. And

if you did something wrong while building your amp, the most likely

outcome is that you'll just blow the fuse.

Step 1: Make sure your AC power cord is NOT plugged in. Do NOT

install any of the tubes yet. Do not plug a speaker into the speaker jack.

Do not plug any instruments into the input jacks.

Step 2: Do not test your amp on a metal table or any surface that can

conduct electricity. Situate yourself and your amp so that the AC power

outlet you will be using is within arm's length.

Step 3: Install your amplifier chassis into the cabinet or enclosure that

you have provided. You should never apply power to the amplifier while

it is not inside its cabinet or enclosure. If you insist on supplying power

to the amplifier while it is not inside its cabinet or enclosure, the safest

way to do so is with the chassis laying on a non-conductive, flame

retardant surface with the transformer side facing down and the open

side of the chassis facing up, making sure that no foriegn objects

(especially any of your body parts) are touching any part of the amp.

Step 4: Install the light bulb or bayonet lamp into the bulb holder.

Step 5: Install the 2 amp fuse into the fuse holder. If you ever need to

change the fuse, never ever do so while the power cord is plugged into an

AC power source. Always unplug the power cord before ever doing

anything, even something as simple as changing a fuse. The fuse is

connected to the mains wire and touching the fuse or fuse holder is the

same as sticking your finger in a wall socket. When installing a fuse,

always insert the fuse into the fuse holder cap first. Then use the fuse

holder cap to insert the fuse into the fuse holder.

Step 6: Turn the amplifier's power switch on, but still do not plug the

power cord in yet. In this case, you do so by turning the volume knob

clockwise (you should install the knob on the volume pot at this point

too). You should hear and feel a click when the switch turns on. You

turn it off by turning the knob counter clockwise till you feel and hear

the same click.

Step 7: Orient the amp so that you can see the indicator light. When

you plug the power cord into the AC power supply, you should be able to

see the indicator light come on immediately.

Step 8: Double check - the amp is not plugged in; none of the tubes are

installed; there are no instruments plugged into the input jacks; there is

no speaker plugged into the speaker jack; and the on/off switch is in the

on position.

Step 9: Now it is time to plug the amp in. Do not touch the amp istelf.

Grab only the insulated 3-prong AC power cord and plug it into the AC

power supply socket. You should see the indicator light come on

immediately. If it does not come on, remove the plug and figure out

what you did wrong. If the light does come on, observe the amp for a

few moments to make sure there's no sparks, smoke, heat, or burning

smells. If you notice anything other than just the indicator light coming

on, unplug the power cord immediately.

Step 10: Unplug the AC power cord. Ok....so now you know your power

transformer is working properly.

Step 11: With the AC power cord unplugged, the on/off switch in the on

position, and no speaker or instruments plugged in, install the 5Y3

rectifier tube. Do NOT install the 12AX7 or 6V6 yet.

Step 12: Plug the AC power cord back in exactly as you did in step 9.

Once again, you should see the indicator light come on immediately.

Once again, if you notice any sparks, smoke, heat, or burning smells,

unplug the power cord immediately and figure out what you did wrong.

Take a moment to observe the rectifier tube. You should see that it is

beginning to warm up and glow. If it's doing this and the fuse hasn't

blown, you can assume that it is working properly. As the tube starts to

get hot, you will probably get a faint smell of something burning. If

you'd like to test voltage before proceeding to the next step, you may.

When testing your amp voltages, always keep one hand in your pocket

and wear shoes with rubber soles. This doesn't reduce the risk of

electrocution, but it will reduce the amount of damage that will be done

if you get do electrocuted. It won't make you impervious to

electrocution, but the less grounded you are, the less the amount of

current that will be able to flow through your body. Doing things like

going barefoot or holding onto a metal drain pipe with your free hand

while working with electricity won't increase the risk of electrocution,

but they will increase how well you conduct current to ground, and that

increases the amount of damage you can do to yourself if you are

electrocuted.

To test the rectified DC voltage, first set your meter to test DC voltage

500V or greater. Then connect the black probe to chassis ground. Then

touch the red probe to the turret lug that connects to the positive end of

the 16uf aluminum electrolytic capacitor. You should see somewhere

around 475VDC. This voltage can vary by as much as 20volts over or

under depending on the actual voltage of your AC power supply. Also

keep in mind, that this voltage will drop significantly when the other

tubes are added.

Step 13: Unplug the AC power cord again.

Step 14: Install the 12AX7 preamp tube, but do not install the 6V6 tube

yet.

Step 15: Plug the AC power cord back in, just as you did in step 9.

You should see the 12AX7 start to glow. If you see this, and there's no

smoke and a fuse hasn't blown, you can assume that everything is

working properly. Preamp tubes do not get very hot. They just get

warm, so it should not produce any sort of burning smell. If you'd like to

test for voltage, you should see approximately 2VDC on the turret lug

where the 1.5k resistor; 25uf aluminum electrolytic capacitor; and

brown wire that connects to pin 3 of the 12AX7 all meet. This voltage

can vary by 1/2 a volt.

Step 16: Unplug the AC power cord.

Step17: VERY IMPORTANT BEFORE YOU ADD THE 6V6 TUBE!!!

Be sure to plug a speaker into the speaker jack. You should never turn

your amp on when the power tube is installed without the proper speaker

load. Doing so will damage your output transformer. Plug a speaker

into the speaker jack. Make sure the impedance of the speaker is 8

ohms. This is very important too. If you are using a 4 ohm speaker,

make sure you have the yellow wire from the output transformer

connected and not the green wire (see Wiring steps 17 - 19 again).

Step 18: Install the 6V6 power tube into its socket and turn the volume

knob counter clockwise to its minimum volume lever, but do not turn it

off.

Step 19: Plug the AC power cord back into the power socket and repeat

all the instructions in step 9 again. You should see the tube start to glow

and it should begin to heat up. As the tube starts to get hot, it will

probably produce a faint smell.

Step 20: Slowly turn the volume knob up and listen for sound coming

out of the speaker. You should hear the normal amount of white noise

you'd expect to hear coming out of an amp with no input signal.

Step 21: Turn the on/off switch to the off position.

Step 22: Plug your guitar (or instrument of choice) into input 1. Turn

the amp back on and play.

[rockabilly69]

The reverb tank arrived today so I fitted it. I remembered to remove the foam packing before screwing it to the base of the cab

 

 

Why no bag for the reverb tank??? This is an honest question, I've never built an amp before!

[big bob]

the tank should not need a bag that far away from the transformers..

[H]

the tank should not need a bag that far away from the transformers..

True - and the dust won't settle under the constant high volume

 

Thanks for the tips above, BB

[kbp810]

I think you've got a handle on this between BB and your own post; when I first started building, I always followed the Ruby slow start guide - it's been a while since I've gone through it step by step though; it's just all sort of second nature to me at this point.

 

Going off of your own list I would add or alter:

On the first full power up, I wouldn't connect a guitar right away - check for noises before an instrument is plugged in (you don't want the guitar to be a variable here yet). Cycle the knobs up and see if any noises are produced and what controls causes or influences the noise. After you are sure you are good here, then you can go ahead and hook up a gitfiddle and put it through some paces (though I also like to let the amp sit on untouched for about an hour or so before trying it out).

 

Reverb bag is really more for aesthetics IMO; though if you're having issues with tank rattle/microphonics, it can help dampen that effect some (and looks better than attaching cardboard sections to it with duct tape - which by the way is very effective, lol). Either way, just make sure the tank isn't tightened down too tight - it needs to "float" on those rubber spacers.

[H]

Thanks KBP - I'm feeling more confident about it all now

 

I know the Ruby guide - I remember you recommending it to me with the testing I did on my 5E3 build - so I'll re-read it and apply it again.

 

Finally, what are the chances of a 1960s layout being correct on the voltage measurements compared with a modern build? Should I allow myself a 10% margin? More?

[kbp810]

Thanks KBP - I'm feeling more confident about it all now

 

I know the Ruby guide - I remember you recommending it to me with the testing I did on my 5E3 build - so I'll re-read it and apply it again.

 

Finally, what are the chances of a 1960s layout being correct on the voltage measurements compared with a modern build? Should I allow myself a 10% margin? More?

Yeah, as long as it's in the ballpark, and within the operating limits of the components (namely tubes), you are good to go - the power grid has indeed changed quite a bit since the 1960's

[H]

So, I now have wiring instructions from ClassicTone, the missing ceramic cap, the two button Fender footswitch and solid advice on testing this circuit. I'm expecting a set of RCA leads in the post tomorrow.

 

This weekend is the one.

[big bob]

Have you contacted any trannies yet. I guess they could cheer for you when everything fires right up.

[H]

It's built. All done except for a couple of teeny things.

 

Sounds pretty good but needs different speakers Reverb doesn't work until my RCA leads arrive. Last but not least, my H logo and the brass name plaque need to be put on. Cover due at the end of next week.

 

Phew

 

 

 

 

Clips soon

[Genericmusic]

Nice, very nice! Congratulations.

[big bob]

Well played!

[rockabilly69]

H, that amp looks great. Funny you don't like those speakers, I have four of them in a 4X10 cab that I don't like either, but

I just use them for my Wurlitzer piano to practice through. The classico alnico speakers from Weber are nicely built, sound

great, and are reasonably priced. Have you checked them out? They come in 15 and watt variants, they also make a

ceramic version and I think they would mix and match well! Here's the 15 watt versions

 

http://www.musiciansfriend.com/accessories/weber-speakers-signature-series-alnico-10s-15w-10-speaker

 

 

http://www.musiciansfriend.com/accessories/weber-speakers-signature-series-ceramic-10-15-watt-10-speaker

[H]

They're a bit more pricy in the UK but, yes, that's the sort of speaker I'll be looking at. I also have the Jensen Jet Tornado and the WGS Veteran on my list.

[TalismanRich]

It's built. All done except for a couple of teeny things.

 

Sounds pretty good but needs different speakers Reverb doesn't work until my RCA leads arrive. Last but not least, my H logo and the brass name plaque need to be put on. Cover due at the end of next week.

 

Phew

 

 

That thing has to sound strange.... you put Marshall speakers in a Fender style amp?? Probably sounds like an American trying to do a British accent!!!!

 

 

 

 

Looks great! I really like the color. Glad to hear that it fired up without any major issues. Looking forward to hearing some clips.

[H]

 

That thing has to sound strange.... you put Marshall speakers in a Fender style amp?? Probably sounds like an American trying to do a British accent!!!!

 

 

 

 

Looks great! I really like the color. Glad to hear that it fired up without any major issues. Looking forward to hearing some clips.

Yes, just like my Limey, a 5E3 with a Greenback in it Seriously, I just had these speakers in storage so I dropped them in to provide the initial sound capability. I have a few ideas on what to put in there - WGS Veteran and Jensen Jet Tornado are on the list, along with the usual Weber candidates and maybe a Greenback.

 

Clips once I have the reverb available - just waiting on a set of RCA leads.

[smokedtires]

That baby turned out beautiful ! Very professional, well done mate.

[H]

The final piece of the puzzle The Eminence speaker pair arrived today, so out came the temporary Celestion full-range pair and in went the Ragin' Cajun and the Legend 1058.

 

Job done.

 

 

 

Of course, I still have to break the new speakers in. I can just imagine the conversation with my wife, "But darling, it says on the interwebz that I have to play at varying volume for twenty hours...."

[212Mavguy]

"Dearest, I need to play these bloody effing loud for 100 hours for breakin... Can you go shopping for a wee bit?"

 

JK

 

Hey brother H,

 

go to the ampgarage site and look for a thread about using a variac to break in a pair of speakers quietly and much more quickly and effectively than the old school way. I don't know the link, but it should be in the Technical or Dumble section within the first 3-5 pages of posting titles. There is a search engine there too. What I do remember is that the speaks are bolted face to face and the motions of the cones oppose each other, cancel them selves out some volume wise as they do their 60hz in-and-out thang. I bet you could get those 10's fully broken in in about 25 hours, and much better job than just playing random music. Or let someone you trust play bass through it for about 25-50 hours at non-destructive volumes, will do the same thing plus if any post assembly rattles decide to appear, that bass will help them to appear and get fixed for good, and also for the speaks, loosen the spiders and surrounds to a broken in state more rapidly than a regular guitar will. Hope this helps. And thanks for all you do to share your build experiences with us.

 

God save the Queen!

[H]

Thanks for the hints I don't have a variac but I am a bass player

 

It's a pleasure to share these builds I've done. I'm hoping that it will help someone else here to make the jump from thinking about building one to actually doing it. I've a feeling that Rockabilly69 may be the first to take a leap

[212Mavguy]

Yes. Barry's right there too.

[TalismanRich]

Of course, I still have to break the new speakers in. I can just imagine the conversation with my wife, "But darling, it says on the interwebz that I have to play at varying volume for twenty hours...."

 

What you need to do is get a JamMan, put a 16 bar blues loop in it and let it run for a day. It will break in the speaker, but it will probably chase off the wife, kids, neighbors and have the local constable banging on the door!