Weber 5E3 Build and Questions

Dortoh5968

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I just completed a Weber 5E3 build in a Hammond aluminum enclosure to fit a custom combo cabinet I built. Everything went well and all the voltage tests are reasonably close to the voltages listed on Rob Robinettes layout. I used Ruby 6v6EH power tubes, a JJ 5Y3 rectifier a Mesa 12ax7 and a JJ 12ay7. My issue is I basically get no distortion at any volume you can stand being in the room with. I tried changing V1 to a 12ax7 and that made a little difference, but not much.
I tested all the voltages and used the output transformer method and came up with a plate dissipation of 10.1 of one tube and 10.39 for the other. I believe these tubes are rated for 14 though I'm not positive. Should a 5E3 be run at 100% plate dissipation?
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lowatter

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I don't possess the knowledge to answer your questions but I have to comment on your clean build and cabinet design. VERY nice!
 

sds1

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Yes they should idle at 12W or 14W depending on the tube...

Not sure what a Ruby 6V6EH is, the "EH" designation sounds like Electro-Harmonix. I didn't find much on the internet about Ruby 6V6's with that designation. The Electro-Harmonix 6V6 idles at 14W max.
 

Dortoh5968

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Yes they should idle at 12W or 14W depending on the tube...

Not sure what a Ruby 6V6EH is, the "EH" designation sounds like Electro-Harmonix. I didn't find much on the internet about Ruby 6V6's with that designation. The Electro-Harmonix 6V6 idles at 14W max.
That is about all the information I could find about the Ruby's as well. My plan is to change the 5 watt resistor to a 220 then check the dissipation again.
 

King Fan

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Something odd if a stock 5E3 is just dissipating 10W. You might share all your voltages and the numbers used in your bias math.

FWIW Rob's cathode resistor voltage drop biasing method is easy — and plenty precise.

And what are your PT specs?
 

andrewRneumann

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Raising the bias current in the power tubes will only give you more clean headroom. One thing I'd be looking for is a grid-leak resistor that wasn't resisting enough. Or possibly input network doesn't have enough resistance on the "high" inputs. Easy to miswire those.

Thank you for posting photos, but the first one isn't clear enough to do any checking of resistance color bands. Crank up the lighting and use the highest resolution TDPRI will let you post.
 

Dortoh5968

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what pt did the kit come with?
The power transformer is a no name Chinese piece. To be quite honest I was pretty disappointed in the quality of the parts in the Weber kit. I replaced the tube sockets with Belton, the pots with CTS and the jacks with Switchcraft.
 

Dortoh5968

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Something odd if a stock 5E3 is just dissipating 10W. You might share all your voltages and the numbers used in your bias math.

FWIW Rob's cathode resistor voltage drop biasing method is easy — and plenty precise.

And what are your PT specs?
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Hopefully you can read my chicken scratch. If not I'll type it all in.
 

Dortoh5968

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Raising the bias current in the power tubes will only give you more clean headroom. One thing I'd be looking for is a grid-leak resistor that wasn't resisting enough. Or possibly input network doesn't have enough resistance on the "high" inputs. Easy to miswire those.

Thank you for posting photos, but the first one isn't clear enough to do any checking of resistance color bands. Crank up the lighting and use the highest resolution TDPRI will let you post.
Here is the best photo I have of the board at the moment. The color bands on the resistors are very translucent and the light blue shows through making reading then tough at the best of time much less in a picture. I'm also attaching the Weber layout. All of the resistors tested to a close tolerance of the layout with the exception of the 2 watt 4.7k which was actually 4.3k.
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5e3_layout.jpg
 

Fluddman

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I sometimes have trouble getting the four input jacks set up correctly. Is it possible you are using the low inputs?

My 5e3 builds are all super clean at home volumes. It's not until I play at gig level (with a drummer) that it starts to breaks up.

This surprised me on the first build.

Good luck sorting this out.
 

Dortoh5968

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I sometimes have trouble getting the four input jacks set up correctly. Is it possible you are using the low inputs?

My 5e3 builds are all super clean at home volumes. It's not until I play at gig level (with a drummer) that it starts to breaks up.

This surprised me on the first build.

Good luck sorting this out.
I've tried every combination of normal, bright, inputs 1 and 2, plus jumping the channels together and interactive volume settings.
 

D'tar

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I cant see the color bands on those resistors. How about a complete voltage chart? On you plate current calc, is that (320vdc)plate to cathode vdc or plate to ground vdc
 

Dortoh5968

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I cant see the color bands on those resistors. How about a complete voltage chart? On you plate current calc, is that (320vdc)plate to cathode vdc or plate to ground vdc
The 320vdc is plate to ground. For your other question about pickups I tried a Les Paul with Humbbuckers and a Gretsch with TV Jones Classics.
 

Phrygian77

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@Dortoh5968 see if you can find a used Eminence Maverick. They discontinued them, so used is the only option. You're not going to find many 12" speakers that are below 97dB. The Maverick goes down to about 91dB. It's like having an attenuator, but it's better.

I had one in my BF Bassman 1x12 combo for years. I recently put it in the last PR that I built. I was able crank that amp in a small bedroom.
 

King Fan

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I see some folks wondering how loud you’re getting your amp. Crude metric, but how far up can you turn the active volume dial?(Say we put tone *and* the inactive volume at 6.)

Lets think more about your low dissipation and low plate voltage… is your 'no-name' PT this (stock) one? The WO number should be stamped into one of the metal bells.

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Next, can you measure *VAC* pin-to-chassis at both *rectifier* pins 4 and 6?

Then how about VDC at rectifier pin 8? And at the bottom (positive pole) of your first filter cap?

And… are you comfortable doing a voltage table? A full voltage table can be written out as a list (V1 pin1 = ___VDC) or recorded in a table like this (this is a minimum data set).

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Phrygian77

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Everyone seems to think there's possibly something wrong with your build. What I got from your original post is that it's too loud.

Your plate voltage is low, which explains the seemingly low bias. That doesn't necessarily indicate problem. Did you use the lower voltage secondary? You don't really want more voltage if it's too loud already.
 




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