Hand wire or PCB in tube guitar amp?

[kldguitar]

I read this articles Articles by Randall Smith - Point to Point Wiring
it is good article to discuss the advantage and disadvantage of PCB and P-T-P board.
But I don't understand author these sentence" 3. Immunity to noise-causing moisture, and 4.It does not warp."
1. material of Base Borad of PCB and P-T-P are same as FR4, why PCB can avoide moisture, but P-T-P cann't.
2. why PCB cann't warp, but P-T-P easy wrap? In fact , PCB warp will cause serious damaged, it maybe cause copper foil broken or level board.

[defaced]

Old PTP boards are not FR4. The old boards can become conductive because of moisture and warp. That is what he's talking about. It's a materials problem, not a construction method problem. If you made a PCB on that substrate, it would have moisture and warping issues too.

[Phostenix]

Here are some links on the subject:

Is Point-to-Point Better Than PCB?

= Bogner Custom Shop =

THD Electronics (scroll almost 1/2 way down the page)

You do realize that this is a religious war, right?
handwired? - Telecaster Guitar Forum

[Old Tele man]

You do realize that this is a religious war, right?

...to some people, to others it's science friction!

[kldguitar]

This article seems not final conclusion

Here are some links on the subject:

Is Point-to-Point Better Than PCB?

= Bogner Custom Shop =

THD Electronics (scroll almost 1/2 way down the page)

You do realize that this is a religious war, right?
handwired? - Telecaster Guitar Forum

Thanks. i have watched this article, but a little help.I still thanks.
1. I think many people confused the sound new amp and amp which used sometime.
Because PCB"s amp installed tube socket on PCB, PCB standed up heat and cold cicyle longer time, The pads of sockets will be produced more inner heat stress, it will effect connection and sound, later stress will cause brokedown.But P-T-P solder on pin by cable, so it is no problem. It is advatage of P-T-P board.
Certainly, I think it is problem only to larger amp such as more than 30w.There is larger current pass through.
about samller amp such as 5w , it is no effect, PCB is same as P-T-P.
the advatange of PCB, it has better consistency

[mooreamps]

I read this articles Articles by Randall Smith - Point to Point Wiring
it is good article to discuss the advantage and disadvantage of PCB and P-T-P board.
But I don't understand author these sentence" 3. Immunity to noise-causing moisture, and 4.It does not warp."
1. material of Base Borad of PCB and P-T-P are same as FR4, why PCB can avoide moisture, but P-T-P cann't.
2. why PCB cann't warp, but P-T-P easy wrap? In fact , PCB warp will cause serious damaged, it maybe cause copper foil broken or level board.

PCB's currently being produced today ; well at least here in the Silicon Valley ; do not have that tendency, at least not that I have seen. Secondly, it's not clear to me just how old said article is. Further, perhaps Mr. Smith was an experienced amplifier technician, but I'm not convinced there is that much "Black Magic" in audio amplifier design ; and I am the one who leans the most toward using the "voodoo" parts and the "mad scientist" kinds of approaches... Now, if he were talking about RF power amplifiers operating in the 2 meter range, well that's where some of the real black magic does come into play ; does it not ?

-g

[jrfrond]

There are MANY instances in electronic design whereas PC boards are desirable, and of course, absolutely necessary. There is no personal/portable electronics industry without them.

Call me old-fashioned, warhorse, or whatever, but for me, tube amps and PC boards just don't belong together, and that's my educated opinion drawn on 30+ years of experience. Yes, I know EXACTLY what all of the advantages of PC boards are, but the disadvantages as well, particularly when you add the physical and thermal stresses of tubes to the mix. Is there ANYONE out there who repairs tube amps that disputes the high incidence of PCB-related failures in tube amps (and guitar amps in general)? Oh, and Mesa/Boogie..... has ANY company ever made a more DIFFICULT guitar amp to work on?

[R.G.]

Call me old-fashioned, warhorse, or whatever, but for me, tube amps and PC boards just don't belong together, and that's my educated opinion drawn on 30+ years of experience. Yes, I know EXACTLY what all of the advantages of PC boards are, but the disadvantages as well, particularly when you add the physical and thermal stresses of tubes to the mix.

I think I'd rephrase that to say that it's your opinion based on 30+ years of experience with PCBs designed by people who are not familiar with the special needs of PCBs inside tube amps.

I have designed tube amps with PCBs inside, and nursed them through production and warranty. The result was that the biggest warranty and reliability issue was - the tubes.

The entire trick is to - as I did - interview some decades-experienced techs and ask them what they did not like about PCBs in tube amps, then don't do what they didn't like, in concert with some common sense.

For instance:
- use thick PCB material to avoid flex
- support it mechanically so it doesn't get stress fractures from vibration
- use substantial copper thickness; I used copper three times the normal thickness for PCBs
- use substantial traces, especially for power and ground
- don't put the jacks, pots, and controls on the PCB, put them on flying wires
- don't put the tubes or tube sockets on the PCB, put them on the chassis, connected by flying wires
- think about what gets hot, and where the heat flows through conduction and hot air rising; put sensitive things where they are not cooked.
- don't make the service guy (as a f'rinstance pointed out to me as a bad example) pull off 20 knobs, 26 pot and jack nuts, 8 PCB mounting screws and a dozen wires, then remove the PCB from the chassis (having previously removed the chassis from the enclosure) before any useful servicing can be done.

It's really not that hard, but you do have to think about it.

Beyond that, you have to think about servicing, because tube amps will need serviced. On our amps, removing the back panel allowed replacement of every pot, jack, switch, and tube socket without removing the chassis from the amp.

Is there ANYONE out there who repairs tube amps that disputes the high incidence of PCB-related failures in tube amps (and guitar amps in general)?

As an historical statement, no. But it is that way only because tube amps done with PCBs are done by people who do not understand tube amp servicing. Tube amp technology was mature before PCBs, and so PCBs were applied to tube amps retroactively by PCB designers that didn't understand the technology.

PCB technology has been applied to tube amps in ways that are hugely inappropriate for the normal functioning of tube amps. It's pretty much inconceivable that anything but bad results would be obtained. That says *nothing at all* about whether PCB technology can or can not be applied well to tube amps, only that it has not been, by and large. The high incidence of failures and unreliability of PCBs in tube amps says bad things about the designers, not of PCBs in general, or even of PCBs in tube amps.

I would add that designing something like an anvil today could well result in not-very-good anvils compared to the ones which were made historically; the specific needs of anvils are less well understood than they once were.

[jpfamps]

Oh, and Mesa/Boogie..... has ANY company ever made a more DIFFICULT guitar amp to work on?

Peavey Classic 30?

[Gregg]

Peavey Classic 30?

Peavey Classic 50!

[teemuk]

Oh, and Mesa/Boogie..... has ANY company ever made a more DIFFICULT guitar amp to work on?

Sure.

[Phostenix]

Maybe not guitar amps, but the old tube amps that don't even have circuit boards - where the components all hang off tube sockets or pots or switches? Or this spectacular example I found on ebay (only $3999 & it's yours) with all the wiring harnesses that would have to be undone to even begin to work on it?

I'd rather work on PCB stuff any day than things like this.

[dkevin]

Thank you, Leo!

I am not a professional amp repairman. But I think there is something to be said for R.G.'s perspective.
I do not think it impossible to design a PCB amp that sounds good and is easy to access and repair. It would take a good deal of thought and care. It is not uncommon to encounter these same issues in almost any field. When I worked in HVAC, we were always griping about design engineers and their lack of understanding of real world issues- ie. how am I gonna fix this thing when it breaks.
This is where I have to say "Thanks!" to Leo Fender. Not all Fender amps were/are easy to access/ repair, but he took pains to shift the design focus in that direction. He ran a radio repair shop and encountered many of the issues we face, albeit with much older technology. When he decided to make amps, he said that he would not manufacture an amp that was not designed with an eye toward future repair.
It is a fact that tube amps require maintenance. It is also a fact that much of modern design is geared toward ease of assembly, not service. When the PCB amp makers decide to focus on the long-term aspects of their designs, these amps will become more desirable. For now, they remain great while they are still new and prohibitively expensive to repair.
Just my 2 cents.

[Albert Kreuzer]

Thank you, Leo!

This.

[R.G.]

Maybe not guitar amps, but the old tube amps that don't even have circuit boards - where the components all hang off tube sockets or pots or switches? Or this spectacular example I found on ebay (only $3999 & it's yours) with all the wiring harnesses that would have to be undone to even begin to work on it?

I'd rather work on PCB stuff any day than things like this.

It's instructive to realize that what you are describing and the photo on the left that you present is, in fact what "point to point, hand wired" really means. It is NOT the eyelet, tagboard, or turret board that all the advertisers of amps keep flogging.

Eyelet board, tagboard, and turret assembly are all steps toward assembly and repair ease and away from the theoretical electronic ideal that true point to point represents. They all have some (or more!) of the supposed drawbacks of PCB design when PCBs are done well, and none of the consistency advantages of PCBs.

Damning PCB construction is very much tossing the baby out with the bathwater.

If you simply must have ease of modding, it makes a great deal of sense to combine turrets with a PCB holding the turrets. Easy to repair. Easy (ish) to mod, and consistent. Funny - nobody does that one, do they?