From Scratch Amp Building Chronicle - 6/13/10 UPDATED!!

[Marshall Law]

can't wait to hear this

 

[lolzgreg]

Clips or you never built it

I haven't been following this thread very long, but I'm excited to hear the amp!

 

[TeleBlaster]

Do what I did. When I spent 6 hours building a Build Your Own Clone treble booster with like 12 parts in it and it didn't work, I slammed it down on the carpet so hard out of total frustration and it immediately started working and still works to this day. I think that's pretty funny but I knew enough not to order another pedal kit.

Note to self:
If I buy a SoCal, do not let Curt set it up.

 

[mentoneman]

I have some bad news guys. As most of you know Steve and I live pretty close to each other. He called me right when he finished the amp and said, "OK, here goes...... I'm flipping the stand by switch". And then I heard a loud ZZZZZZAAAAAAPPPPPPPP! and smelled sulfur and all the lights in my shop went out. The entire #17 electrical grid in Orange County is still down and Steve is not picking up his phone. I'm getting kind of freaked out!!!!

Actually the news of my demise is greatly exaggerated... However...

I DID forgot to order tubes.... so.... I gotta wait until a matched quad and some preamp tubes show up to begin testing...

Testing to begin next week...

Steve

oh not so fast pinnochio

you have a perfectly rob- able eggie seminar head loaded with glass.

get a-swapping mr next week.

 

[Anonymous]

I have some bad news guys. As most of you know Steve and I live pretty close to each other. He called me right when he finished the amp and said, "OK, here goes...... I'm flipping the stand by switch". And then I heard a loud ZZZZZZAAAAAAPPPPPPPP! and smelled sulfur and all the lights in my shop went out. The entire #17 electrical grid in Orange County is still down and Steve is not picking up his phone. I'm getting kind of freaked out!!!!

Actually the news of my demise is greatly exaggerated... However...

I DID forgot to order tubes.... so.... I gotta wait until a matched quad and some preamp tubes show up to begin testing...

Testing to begin next week...

Steve

oh not so fast pinnochio

you have a perfectly rob- able eggie seminar head loaded with glass.

get a-swapping mr next week.

Only 2 EL34s in a 50 watt Eggie... I need a matched quad for my amp...

Steve

 

[Roland]

I have some bad news guys. As most of you know Steve and I live pretty close to each other. He called me right when he finished the amp and said, "OK, here goes...... I'm flipping the stand by switch". And then I heard a loud ZZZZZZAAAAAAPPPPPPPP! and smelled sulfur and all the lights in my shop went out. The entire #17 electrical grid in Orange County is still down and Steve is not picking up his phone. I'm getting kind of freaked out!!!!

Actually the news of my demise is greatly exaggerated... However...

I DID forgot to order tubes.... so.... I gotta wait until a matched quad and some preamp tubes show up to begin testing...

Testing to begin next week...

Steve

Fuck'n Classic!

 

[GITTarzann]

Soooooo ????????????????

I woulda drove a thousand miles to get tubes for something I had been working on of this caliber !!

 

[Anonymous]

Soooooo ????????????????

I woulda drove a thousand miles to get tubes for something I had been working on of this caliber !!

Ordered what I really wanted from Doug's Tubes. Should be here by the weekend!

Steve

 

[GITTarzann]

fair enough.

the suspense is KILLING me

 

[Anonymous]

fair enough.

the suspense is KILLING me

Hey, me too!!!

Steve

 

[Anonymous]

Alright... got my tubes and started testing...

Throughout the below process, I found some mistakes and fixed them.

First I put in the preamp tubes and plugged in the amp. Measured 120.4 VAC at the live terminal of the IEC socket and the power switch. Good...

Flipped on the power switch... Preamp tubes light up... Measured between 6.1-6.2 V DC heater voltage on the preamp tubes measured from pin 4 to pin 9. Seeing 3.3-3.4 VAC on pin 2 and 3.5-3.6 VAC on pins 7 of the EL34s... A bit high, but ok...

Checked Pin 5 of each EL34 and found -51V... Ok...

Turn the amp off, drain the filter caps. Put in the EL34s... Threw the power and standby switch on... Starting taking measurements...

V5 EL34 Pin 2 - 3.315 AC, Pin 3 - 460.5, Pin 4 - 458.8, Pin 5 - -40, Pin 6 - 458.6, Pin 7 - 3.485
V6 EL34 Pin 2 - 3.336 AC, Pin 3 - 460.5, Pin 4 - 458.8, Pin 5 - -40, Pin 6 - 459.6, Pin 7 - 3.52
V7 EL34 Pin 2 - 3.364 AC, Pin 3 - 460.3, Pin 4 - 458.6, Pin 5 - -40, Pin 6 - 460, Pin 7 - 3.562
V8 EL34 Pin 2 - 3.388 AC, Pin 3 - 460.6, Pin 4 - 458.7, Pin 5 - -40, Pin 6 - 459.5, Pin 7 - 3.625

Ok, time to bias the EL34s... I've got 1 Ohm 5 Watt resistors from pin 8 to pin 1 to ground. Check V5 and pin 1 and adjust the bias pot, mess with it a bit and I get:

V5 EL34 34.8 mV
V6 EL34 33.1 mV
V7 EL34 36.6 mV
V8 EL34 37.5 mV

Ok, good enough...

My relay power supply is measuring 6.085 VDC and I get the same reading at the coil of each relay, so it looks like the relay supply is working...

None of my switching LEDs is lit though... Flipping the manual switches doesn't light any of them... Hmmmm.... Start checking some of the manual switches - definitely something wrong with the switching...

Troubleshooting continues...

Steve

 

[dstroud]

Dude, sounds like you are very close!

 

[Anonymous]

Dude, sounds like you are very close!

Well... lotsa stuff could still be wrong... but, I'm encouraged by the things that look ok... Ya just gotta take it one section at a time...

I'm thinking about the switching... I'm seeing some strange stuff, but I think I can get it figured out...

Steve

 

[Anonymous]

Code for the freaking amp doesn't work!!!!

Correct. But I'm on it...

Steve

 

[duesentrieb]

Start from the "backside", poweramp working?, PI working?, Loop working ? - those are not affected by the switching.
If they work (guitar into return) have a look at the switching, Steve.

If the return doesn't work, interrupt the loop to PI connection (jack) and go directly into the PI, Steve. Check the PI voltages and the NFB-circuit.

Good luck.

 

[Dallas Marlow]

This is awesome I've been following the thread since the start... good luck getting it figured out, it's gotta be frustrating not being able to play it!!! Looks sickkkk as hell dude can't wait to hear it!!!!

Dallas

 

[Anonymous]

Start from the "backside", poweramp working?, PI working?, Loop working ? - those are not affected by the switching.
If they work (guitar into return) have a look at the switching, Steve.

If the return doesn't work, interrupt the loop to PI connection (jack) and go directly into the PI, Steve. Check the PI voltages and the NFB-circuit.

Good luck.

Thanks Olaf - just PM'd you with some questions (I'm sure you knew that was coming! )

Steve

 

[Anonymous]

This is awesome I've been following the thread since the start... good luck getting it figured out, it's gotta be frustrating not being able to play it!!! Looks sickkkk as hell dude can't wait to hear it!!!!

Dallas

Thanks man - I'm actually not frustrated at all because I fully expected that I'd have some troubleshooting to do with something this complex. No way I was gonna get it all right the first time. I've already found and fixed several issues just to get to this point.

Steve

 

[cyndicate]

This is awesome I've been following the thread since the start... good luck getting it figured out, it's gotta be frustrating not being able to play it!!! Looks sickkkk as hell dude can't wait to hear it!!!!

Dallas

Thanks man - I'm actually not frustrated at all because I fully expected that I'd have some troubleshooting to do with something this complex. No way I was gonna get it all right the first time. I've already found and fixed several issues just to get to this point.

Steve

Hope you get it fixed soon Steve. I can only imagine how long it's going to take to track down the problem, it took me forever to find the screw up on my build and I don't think its nearly as complicated as yours.

 

[Anonymous]

This is awesome I've been following the thread since the start... good luck getting it figured out, it's gotta be frustrating not being able to play it!!! Looks sickkkk as hell dude can't wait to hear it!!!!

Dallas

Thanks man - I'm actually not frustrated at all because I fully expected that I'd have some troubleshooting to do with something this complex. No way I was gonna get it all right the first time. I've already found and fixed several issues just to get to this point.

Steve

Hope you get it fixed soon Steve. I can only imagine how long it's going to take to track down the problem, it took me forever to find the screw up on my build and I don't think its nearly as complicated as yours.

Yes and I fully expect to find multiple issues. My biggest concern is the amount of board interconnects I have that are underneath it. If I narrow down a problem there, the whole board has to be de-soldered and come out so I can get under it... that will be a major pain, but whaddaya gonna do?

I think I'm going to do my next board differently to avoid under board interconnects, but there are trade-offs both ways. For production I may have no choice but to go PCB... we'll see...

Steve