Tube socket wiring?

[Uncle Daddy]

Would this be considered a good example of tube socket wiring?



As opposed to Robrob's nice example?

 

[sds1]

Everything looks tidy, but the heater wires are not twisted and the leads from the board are too long, according to best practices.

However if the amp works well and is relatively noise-free then I supposed it's a good example. We've all seen worse.

 

[King Fan]

That's a photo from the Speed Shop / recproaudio 5e3 page? I don't know their products, but as far as I can tell they go to some trouble (in idiosyncratic or unusual ways) to engineer an amp. So those heaters might indeed be quiet. As sds1 says, many amps are worse, including tons of 70s Fenders where the heater wires just loop lazily through space.

 

[Snfoilhat]

http://www.valvewizard.co.uk/heater.html

Scroll down to the bottom of the page and compare the sad face wiring to the happy face wiring.

Despite the low headroom and rocker mystique, amps like the Deluxe in your first photo are pretty low gain and often tolerate really poor lead dress. But those weird, sharp bends in the heater wiring are -- and this is just one person's opinion here -- just to impress impressionable people on the internet.

Check out the rest of that 5E3 -- many of the other leads at each socket run close and parallel, there's a wire nut on one of the power transformer connections. It might run great, play great, and sell great, but I wouldn't use it as your template for great work, FWIW. Cheers

 

[King Fan]

http://www.valvewizard.co.uk/heater.html

Scroll down to the bottom of the page and compare the sad face wiring to the happy face wiring.

Despite the low headroom and rocker mystique, amps like the Deluxe in your first photo are pretty low gain and often tolerate really poor lead dress. But those weird, sharp bends in the heater wiring are -- and this is just one person's opinion here -- just to impress impressionable people on the internet.

Check out the rest of that 5E3 -- many of the other leads at each socket run close and parallel, there's a wire nut on one of the power transformer connections. It might run great, play great, and sell great, but I wouldn't use it as your template for great work, FWIW. Cheers

True, true, and very true.

The orange jewel’s also a clue.

Worse than that, the wire nut’s blue.

Because it rhymes, this ain’t haiku.

[emoji846]

 

[Snfoilhat]

I feel bad for nitpicking someone else's work. My own is considerably messier. I think the overall message is hopeful -- if CBS/Fender could get away with that lead dress in their pretty well loved production amplifiers, then we know the bar low enough we mortals can get over.

Until you decide to build something high gain, and then reap all the hum and oscillations you sowed building sloppy tweed and BF/SF clones.

May as well copy the best from the start, learn good habits early. No telling when they will save you from some chop-sticking nightmare.

 

[Bill Moore]

From experience I think the top pic would be very quiet! Notice that all signal wires cross at 90 deg, and the heater wires are close to the chassis. The Fender Pro Tube series amps were wired with the heater wires close to the chassis, and the signal wires flying above

 

[clintj]

That pic is interesting. Yes, the heaters are untwisted but look at the whole socket. Any signal leads are run in such a way to cross them at 90° to maximize hum rejection. There are some good builders out there that route heaters untwisted, but meticulously paralleled, and get excellent results as well.

FWIW, I use Merlin's approach and cross the socket in the middle.

 

[galaxiex]

Look at Hoffman amps Blues Junior tube board page.
He doesn't twist the heater wiring and claims it's quiet.

http://el34world.com/Hoffman/Blues_Junior_Tube_Board.htm

 

[SacDAve]

My 18 watt build heater wires dead quiet

 

[Nickfl]

Look at Hoffman amps Blues Junior tube board page.
He doesn't twist the heater wiring and claims it's quiet.

http://el34world.com/Hoffman/Blues_Junior_Tube_Board.htm

Soldano does it too, with much higher gain amps I might add. Twisting isn't functionally what cancels hum it is just an easy way to keep the heater wires equidistant across their run, which is what actually cancel the radiated hum. That's why the method Hoffman is using works. The OP's first example on the other hand isn't doing that, it seems to use a big wide loop on the preamp tubes so it can cross the signal leads at a right angle and or just for appearance sake. That being said I imagine the amp sounds fine, because as mentioned above you can get away with a lot on something like a 5e3, it's just not best practice. I think all of this highlights that there's a difference between neat looking work and correct lead dress. They don't necessarily go together.

 

[elpico]

That pic is interesting. Yes, the heaters are untwisted but look at the whole socket. Any signal leads are run in such a way to cross them at 90° to maximize hum rejection. There are some good builders out there that route heaters untwisted, but meticulously paralleled, and get excellent results as well.

FWIW, I use Merlin's approach and cross the socket in the middle.

The ability of a pair of wires to radiate hum into other circuits depends on the rate of change of the current they carry, the area enclosed by those wires (ie. square inches), and the distance between that loop and their potential victims.

A 12AX7 draws only a 1/3rd of an amp and that current is changing very slowly so logically you can get away with a lot more there than for example the 10x higher current drawn by a pair of EL34. Whether you twist the wires or not keeping them both close together will reduce the area enclosed by that current loop (which makes it a much less effective antenna for transmitting noise into your other wires).

 

[robrob]

Unfortunately this "nice example" picture above was from before I chopsticked that amp and separated the plate and grid wires on V1 and V2. I would not consider it a very good example of tidy lead dress. The 5E3 amp as pictured had a pretty good hum caused by the V1A pin 1 & 2 leads sitting on top of one another (at extreme right in photo). The hum completely disappeared after separating those wires. I now prefer the ValveWizard's method of heater wiring for tweed amps with their heaters down on the chassis floor. I like flying twisted leads for more modern amps.

I'm not a fan of this style of socket wiring because the signal wires, especially the plates and grids, overlap and run parallel too much.

 

[Phrygian77]

Did anyone notice how close that board mounting screw is to the V1B plate eyelet and resistor lead?

 

[robrob]

Did anyone notice how close that board mounting screw is to the V1B plate eyelet and resistor lead?

That's a nylon nut and bolt.

 

[Phrygian77]

That's a nylon nut and bolt.

I was referring to the other picture/amp.

 

[robrob]

I was referring to the other picture/amp.

Wow, I didn't notice that.

 

[Phrygian77]

Wow, I didn't notice that.

Yeah, I think that it has bad written all over it, even though it is attempting to look impressive.

 

[LudwigvonBirk]

Also: what's going on with the second capacitor from the right? Did the builder cut a chunck out of the cap to make room for the input jack??

Edit, nm, bad eyes. Once I zoomed in it looks like the jack is just in front of the capacitor. Whew!

 

[King Fan]

I can think of several amp shops that don't do themselves a favor by publishing gut shots. But I wonder if I was being unfair to that particular amp shop. My initial assumption was that was their shop-built amp, but the whole structure of that page is confusing. It looks like a home-brew blog from 10 years ago, (it is *old*) showing three very different 5e3 builds -- one is true PTP. So I'm not gonna assume they were showing off their own work -- in fact, that amp's description says 'DIY' so maybe it was a kit someone built. There's a reason home-brew blogs fell from favor.

Also, let's admit the 5e3 chassis makes it a bit hard to get all the ants neatly into the ant farm.We all see plenty of DIY amps that run from 'dump cake' through 'ugly cake' and 'homemade cake' to 'angel food cake.'

In addition to the point that poorly-wired amps can be quiet (Snfoilhat nailed the aspects of that issue) Rob's modest post above also points out that even 'good' lead dress may fail to be quiet.

So I'll try to be neat, follow best practices, read Merlin, and lay my wire down hard in just the right place. But then I'll listen to the amp and see what she's telling me if she hums and hisses.