First 18w build - EF86 Lite 2P

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Re: First 18w build - EF86 Lite 2P

Post by JMPGuitars »

Some of the turrets are fine, just clean up and add to the ones that look thirsty.
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Re: First 18w build - EF86 Lite 2P

Post by yello »

JMPGuitars wrote:
Wed 05/04/22 1:40 pm
Some of the turrets are fine, just clean up and add to the ones that look thirsty.
I had originally thought they looked pretty good - but now that I have added solder I can see the difference, much better now.
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Re: First 18w build - EF86 Lite 2P

Post by yello »

Just did the highlighter check of my schematic versus my amp, wire by wire, part by part. I had confidently assumed I wouldn't find mistakes as I was methodical with everything...

...but, I see why its a good exercise, and saves frustration later, I found a mistake! I didn't connect the heater wire at pin 5 of v2, only had it going to pin 4.

Everything else looked fine, short of I still need to order my pilot light and install it. I'll be using a 120v amber light.

Image

Next I need to read through start-up procedures: https://robrobinette.com/Tube_Amp_Startup.htm

And I think I have some vintage tubes I can pop in - I wanted to try reissue Mullards but I can't find them in stock.
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Re: First 18w build - EF86 Lite 2P

Post by yello »

Fixed the lone mistake I located in my highlighter test, added a jumper between pins 4 & 5 on the v2 12ax7.

Here are the two tubes set I found in my stash that might work:

1) New set of JJ ez81, el844's, 12ax7, and vintage Mullard ef86.

OR

2) Vintage Rogers ez81, vintage Baldwin organ el84's, NOS GE 12ax7, and an Amperex ef86.

Either ef86 could work with either setup.

I'm leaning towards the JJ's at first as they are new and in theory will function (in a bid to eliminate a tube problem being confused for an amp problem) then would switch to using the vintage tubes to play the amp. (Josh read my mind while I was editing my post to say the above).

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Last edited by yello on Wed 05/11/22 1:30 pm, edited 4 times in total.
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Re: First 18w build - EF86 Lite 2P

Post by JMPGuitars »

lol, close. Throw the JJs in to test. Once the amp is tested and you know it's all good, put in the better tubes.
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Re: First 18w build - EF86 Lite 2P

Post by yello »

Initial amp startup questions (gleaned from reading these start-up procedures):

https://robrobinette.com/Tube_Amp_Startup.htm:

1) Do I need to form new caps slowly with a variac (robinette says it isn't necessary but is helpful)?
2) As I understand it, no speaker load needed until the point of putting in power tubes, correct?
3) Should voltage reading for the circuit be taken with a light bulb limiter and/or variac in place?

If answer to 1 and 3 is no, then I assume I use my limiter at first to ensure no shorts, then move on to full power and test/measure appropriately from there.
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Re: First 18w build - EF86 Lite 2P

Post by Bieworm »

yello wrote:
Wed 05/11/22 3:37 pm
Initial amp startup questions (gleaned from reading these start-up procedures):

https://robrobinette.com/Tube_Amp_Startup.htm:

1) Do I need to form new caps slowly with a variac (robinette says it isn't necessary but is helpful)?
2) As I understand it, no speaker load needed until the point of putting in power tubes, correct?
3) Should voltage reading for the circuit be taken with a light bulb limiter and/or variac in place?

If answer to 1 and 3 is no, then I assume I use my limiter at first to ensure no shorts, then move on to full power and test/measure appropriately from there.
It's best to use the lightbulb current limiter for initial start up. The variac is not really required but since you have one.. why not?
Measure voltages of the B+ nodes with the light bulb installed. The voltages should be lower than specced, and this gives you an indication that everything is on par.
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Re: First 18w build - EF86 Lite 2P

Post by yello »

Bieworm wrote:
Thu 05/12/22 2:12 am
It's best to use the lightbulb current limiter for initial start up. The variac is not really required but since you have one.. why not?
Allright, found time to begin initial startup - all is well with limiter, no shorts.

I used my Variac (after completely reworking the Variac wiring and plugs) to slowly form the caps last night.

Tonight I will finish testing and measuring with tubes and then load, and then guitar. Fingers crossed!

My 120v pilot light just arrived in the mail this afternoon. How do I wire it, one wire to neutral (on IEC or transformer?) and one wire connected to hot (either at the switch or fuse or transformer?)?
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Re: First 18w build - EF86 Lite 2P

Post by yello »

Took first stab at voltages with light bulb limiter in place, with a 29w bulb:

Image

I imagine next step is to remove the limiter and take voltages again?
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Re: First 18w build - EF86 Lite 2P

Post by yello »

And here are the voltages without the limiter:

Image
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Re: First 18w build - EF86 Lite 2P

Post by yello »

I'll have time for more extensive sound testing on friday, but sounds great at first sound test. I don't hear or experience any issues. Sounds pretty awesome! And it's loud.

Here is a very hasty sound clip:

https://www.youtube.com/shorts/AeE9QVIuAlM
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Re: First 18w build - EF86 Lite 2P

Post by Unit_1 »

Sounds great! 8)
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Re: First 18w build - EF86 Lite 2P

Post by JMPGuitars »

Sounds great, well done!

Assuming you're using the 180 ohm cathode resistor I sent, then you're tube dissipation is at 70%, which is great.

Awesome job, enjoy your new amp!

Are you going to build a cabinet, or try and source one?

Thanks,
Josh
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Re: First 18w build - EF86 Lite 2P

Post by Bieworm »

Nice sound!!!

Here's a layout of an amp with the 120V pilot. Try to figure it out on yours...
Thor_Layout.jpg
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Re: First 18w build - EF86 Lite 2P

Post by yello »

JMPGuitars wrote:
Thu 05/19/22 7:06 am
Sounds great, well done!

Assuming you're using the 180 ohm cathode resistor I sent, then you're tube dissipation is at 70%, which is great.

Awesome job, enjoy your new amp!

Are you going to build a cabinet, or try and source one?

Thanks,
Josh
Every part in the amp is what you sent. The layout and instructions were awesome, and the assistance from everyone who chimed in here very helpful. THANK YOU! I've been learning a ton between this and the projector amp troubleshooting.

VERY cool that it works - I've modded several amps, but that is a great feeling for my first complete scratch amp build to fire right up and sound great!

For an enclosure, I'm still pondering/looking. Some of the amps I like are traditionally put in an ammo can, and I might try that for fun on this one. Or if I can find a good Marshall-esque headshell, looking for used at the moment.

Next I'll try my vintage tubes in the amp to see how they sound.
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Re: First 18w build - EF86 Lite 2P

Post by yello »

Bieworm wrote:
Thu 05/19/22 7:34 am
Nice sound!!!

Here's a layout of an amp with the 120V pilot. Try to figure it out on yours...
Thanks! I like the sound and will explore more tomorrow when no one is home and I can crank it up.

Diagram helps for wiring the 120v.

Things left to do on the amp:

1) Wire in 120v pilot light.
2) Redo the HV wires to the rectifier (I forgot to twist them and they are a little short).
3) Install and test with vintage tubes instead of the current new production JJ's.
4) I'm pondering adding a Type 3 PPIMV - I figure I can alligator clip a pot in to see if I like it.
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Re: First 18w build - EF86 Lite 2P

Post by JMPGuitars »

yello wrote:
Thu 05/19/22 10:22 am
Every part in the amp is what you sent. The layout and instructions were awesome, and the assistance from everyone who chimed in here very helpful. THANK YOU! I've been learning a ton between this and the projector amp troubleshooting.

VERY cool that it works - I've modded several amps, but that is a great feeling for my first complete scratch amp build to fire right up and sound great!

For an enclosure, I'm still pondering/looking. Some of the amps I like are traditionally put in an ammo can, and I might try that for fun on this one. Or if I can find a good Marshall-esque headshell, looking for used at the moment.

Next I'll try my vintage tubes in the amp to see how they sound.
I'm glad everything worked out so well! Yes, it is a much cooler file (at least to me) when building from scratch vs. modding stuff.

You should try contacting Jeff at Swanson Cabinets, he should have the plans to make a cabinet for you.

I imagine the amp should sound even better with real tubes replacing the JJs. ;)

Thanks,
Josh
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Re: First 18w build - EF86 Lite 2P

Post by yello »

JMPGuitars wrote:
Thu 05/19/22 10:57 am
I'm glad everything worked out so well! Yes, it is a much cooler file (at least to me) when building from scratch vs. modding stuff.

You should try contacting Jeff at Swanson Cabinets, he should have the plans to make a cabinet for you.

I imagine the amp should sound even better with real tubes replacing the JJs. ;)
Agreed, new build was very satisfying, and much easier.

I'll post videos of the amp with JJ's versus vintage tubes, and report if I hear and feel a difference when playing. Either way, v1 is a vintage Mullard.

Any thoughts on how a type 3 PPIMV would sound or react in this one?
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Re: First 18w build - EF86 Lite 2P

Post by Bieworm »

yello wrote:
Thu 05/19/22 10:44 am
Bieworm wrote:
Thu 05/19/22 7:34 am
Nice sound!!!

Here's a layout of an amp with the 120V pilot. Try to figure it out on yours...
Thanks! I like the sound and will explore more tomorrow when no one is home and I can crank it up.

Diagram helps for wiring the 120v.

Things left to do on the amp:

1) Wire in 120v pilot light.
2) Redo the HV wires to the rectifier (I forgot to twist them and they are a little short).
3) Install and test with vintage tubes instead of the current new production JJ's.
4) I'm pondering adding a Type 3 PPIMV - I figure I can alligator clip a pot in to see if I like it.
Regarding pt.4: you'll have to be aware that a MV has to be done very tidy. Clipping it in WILL be noisy, and will be better when it's properly done. Use shielded wire for sure!
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Re: First 18w build - EF86 Lite 2P

Post by JMPGuitars »

yello wrote:
Thu 05/19/22 11:08 am
Any thoughts on how a type 3 PPIMV would sound or react in this one?
I'm not the guy to ask about PPIMVs, I don't like them. I use an attenuator if I need to drop the volume.
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