Why do guitar forums have these PCB vs PTP debates?

On a number of guitar forums it seems folklore that any amp that is PCB based is junk and only PTP will get you any cred. The most common piece to be cast off as total "junk" on these forums are fender reissue amps which are PCB based - I find it hard to believe that just because something is PCB based it could be that bad, although I accept that sometimes, such as the case of reissued gear , their choice of components may not be brilliant (microphone manufacturers are guilty of this too). These amps are consistently bashed on the basis that unless you pay some amp tech heaps of cash to completely gut out the entire innards of the amp and start it again as a PTP circuit, the amp is total crap.

Now before I throw a little tantrum about how naive this thinking is, usually predicated by "expert" guitar players whom know nothing about electronics other that you plug a guitar in, I need to clarify that I an not missing something. Is there something to this PTP obsession that I have overlooked?

I mean, my thinking about an amp's sound is that it stems from the quality of its transformers, its filter caps, its tone stack caps, and the valves themselves. I accept that PTP may structurally be stronger than a brittle PCB if such a PCB is a mass produced cheap one. But assuming one has quality iron, nice caps and nice valves, PCB v turret/ PTP shouldn't be an issue. 

I expect when it comes to amp techs, a repairer prefers to work on PTP if only because its easier to replace components without damaging a PCB, but other than that I still wonder whether I am missing something

Do quality of pots make that much of a difference? Does wiring in such a small space make really such a difference unless it is total appallingly terrible wiring and so bad it would not pass for a production line amp such as a Fender? I am unsure with that one. I accept that DIY builds can often sound dissappointing because of poor wiring, but presumably these factor mass produced things must have some basic level of wiring. Can this really be that bad? Am I missing something?

Resistors to my ears dont seem to make much difference to tone. Maybe I am just deaf.

I am keen to hear from actual electronics knowledgeable guys like you what your take on it is.

These are the same dudes that insist blue wire sound different from red wire, because the dyes and pigments used add capacitance to the insulation... Don't try to reason with them, it's a loosing battle.

Really it's all about keeping their vintage gear valuable. They don't people to know that you can get a pcb based amp, change a few components and get a killer sound out of it...rivaling the old P2P amps they're designed after.

Its the components that potentially impact on sound and not the PCB or P2P board. The argument is really only relevant to longevity, PCB's in a high powered tube amp that generates lots of heat may have trouble in years to come, the board could warp, tracks could fracture, periodical replacement of pots and caps may result in accidental damage of PCB tracks. Its quite a pain replacing PCB mounted pots on a PCB amp and difficult to not damage the board.

Whereas a P2P turret board is "generally" much thicker, less lilkely to warp and hence less risk of something breaking and you can change components with little risk. This is why you can still easily service and maintain a 50 year old Marshall. You will not be able to as easily maintain a PCB amp for 50 years.

P2P boards then also easily lend themselves to easy modification, which some feel they must do to make themselves feel better about their amp.

Thats it's, the rest is bullsh*t.

Michael

I mean, my thinking about an amp's sound is that it stems from the quality of its transformers, its filter caps, its tone stack caps, and the valves themselves.

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I've played guitar professionally for 20+ years and I would say that to my ears the biggest factors that affect the overall sound are , in no particular order, circuit type (SE vs PP),  cabinet type (open back combo vs head closed back cab),  power tube type, relative simplicity ( from no tone stack all the way up to the "army of capacitors" style of Mesa Boogie - massive mid boost), relative health of the amp (are the voltages in spec or way off?, caps leaky?),  speaker size and type, output transformer.

On the question of PCB.  A good friend of mine owns a boutique amp Co and makes a good deal of his income off of modding amps.  One of his specialties are the modern Fender Blues Deville, Blues Deluxe etc which I believe are all PCB amps.  He doesn't gut them but just mods from the PCB.  Lots of people rave about his mods.  I've played one and wouldn't think of trying to convert it to P to P.  I've played plenty of unappealing PCB amps and plenty of unappealing P to P amps.

If I had to hazard a decent guess as to why the PCB amps get bashed I would suggest that it may have something to do with there being an increasing number of commercial amps on the market that many players aren't satisfied with and PCBs get caught in the speculations and witchhunts.

IMO the sensible thing to do would be to have 2 amps built to exact specs, exact components differing only in PCB vs P to P and do a blind A/B test.  This may help settle the question to a certain extent but often it isn't practical.

If there is a difference I'm inclined to believe it would fall into the more subtle category which may or may not be a deal breaker for some players.  I think sweeping generalizations here should be avoided though.

lassoharp said:

I mean, my thinking about an amp's sound is that it stems from the quality of its transformers, its filter caps, its tone stack caps, and the valves themselves.

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On the question of PCB.  A good friend of mine owns a boutique amp Co and makes a good deal of his income off of modding amps.  One of his specialties are the modern Fender Blues Deville, Blues Deluxe etc which I believe are all PCB amps.  He doesn't gut them but just mods from the PCB.  Lots of people rave about his mods.  I've played one and wouldn't think of trying to convert it to P to P.  I've played plenty of unappealing PCB amps and plenty of unappealing P to P amps.

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And I guess this is the crux of the PCB issue -if you buddy is seriously improving tone, its his changes to either actual circuit or the components or both. The platform itself surely cant be the issue.


I am enjoying your responses guys. Funny how electronics heads see things distinctly from musicians. We are a unique breed here, - most of us are both!  I think this is a profound point to consider even in regard to all other  builds on this board. Our perceptions of gear and the opinions we hold are very valuable because we operate from a pretty privileged base - both worlds.

As mentioned by another poster, I think a large part of it is that guitar amp techs generally prefer working on PTP circuits- mostly simpler circuits, easier to track down problems, and usually more space.  When this means you can get an amp up and running in 30 minutes it's a major benefit to a player.

I will say that of all my amps, I've never had a failing in a PTP amp of anything but tubes.  I've had numerous failures in most  of my PCB amps though, and I only have one PCB amp I would consider a cheapy- the rest are expensive/boutiquey sort of things. 
I'm not going to offer a guess why this is, but it has been something I've noticed. 
I don't believe any nonsense about them sounding different enough to notice though.

All of what's been said is true but there is one other issue about PCB's which bugs me.  You can only ever get a ground or earth track that contains relatively little copper.  Thin tracks are not an issue for the signal currents but for heavy current flows you need some serious copper in order to have low resistance and hence low hum.  The very first PtP amps were hand-made and had large dia tin plated copper busbars running through the amps and all the components were soldered in directly with few boards.  Later on in an effort to speed up production, components were fixed to turret boards for ease of production and maintenance.  In both of these latter methods it is possible to have minimum hum with star grounding on the earth wiring.

The modern trend is to have one smart guy designing a layout then machines or bozos thoughtlessly constructing mass produced pcbs.  The old way had skilled technicians taking a pride in their work, you can tell that I don't like the way the world has gone I think.  The only good thing about the present situation is that lots of us have mass produced crap instead of just a few rich people having quality products.

Rant over
best
DaveP

DaveP said:

The modern trend is to have one smart guy designing a layout then machines or bozos thoughtlessly constructing mass produced pcbs.  The old way had skilled technicians taking a pride in their work, you can tell that I don't like the way the world has gone I think.  The only good thing about the present situation is that lots of us have mass produced crap instead of just a few rich people having quality products.

Rant over
best
DaveP

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I don't think you can for example call a Soldano SLO100 amp "mass produced crap" and that amp is pcb based. And i also doubt that Mike Soldano doesn't take pride in his amps and designs, just like Reinhold Bogner.
People should stop thinking "pcb amp = crap amp". An amp based on pcb can be very good or can be very bad, it really depends on the amp itself. But generalizations never help in any way.
People claiming ptp is superior in terms of sound to pcb based amps are mostly either vintage amp collectors fearing for the value of their prized possessions or boutique amp manufactures who search for a way to justify their insame prices, simply because it's that "vintage ptp design".

I don't think you can for example call a Soldano SLO100 amp "mass produced crap" and that amp is pcb based. And i also doubt that Mike Soldano doesn't take pride in his amps and designs, just like Reinhold Bogner.
[/quote]

I don't think the amps you are referring to, are what I would call mass produced, maybe I should have made it clearer that I was talking about the electronics industry in general.

best
DaveP

DaveP said:

... The old way had skilled technicians taking a pride in their work...

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with

DaveP said:

... just a few rich people ...

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makes sense
the skilled technicians want to be paid ;D

but back on topic - [I'm not a guitar player btw] - I doubt there is any sound difference between a PCB and P2P.

always remember jensenmanns signature:

PRR said:

The tubes of course don't care what frequency they distort

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which could be translated to "electrons don't care working in a PCB or P2P"

deuce42 said:

Why do guitar forums have these PCB vs PTP debates?

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That's because Real men use Vero.

tv said:

deuce42 said:

Why do guitar forums have these PCB vs PTP debates?

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That's because Real men use Vero.

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I'm sorry, is that some form of oral contraceptive?  "My doctor recommends, Vero, twice a day"

tv said:

deuce42 said:

Why do guitar forums have these PCB vs PTP debates?

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That's because Real men use Vero.

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For high voltage? Well, to each his own... Also, at 1,xmm thickness and the complete surface perforated with holes, way too fragile for my taste.

DaveP said:

All of what's been said is true but there is one other issue about PCB's which bugs me.  You can only ever get a ground or earth track that contains relatively little copper.  Thin tracks are not an issue for the signal currents but for heavy current flows you need some serious copper in order to have low resistance and hence low hum.  The very first PtP amps were hand-made and had large dia tin plated copper busbars running through the amps and all the components were soldered in directly with few boards.  Later on in an effort to speed up production, components were fixed to turret boards for ease of production and maintenance.  In both of these latter methods it is possible to have minimum hum with star grounding on the earth wiring.

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A 35µm copper trace of 3mm width will heat to 30°C at 8A current. Good enough for the heater demands of the run of the mill amp with four EL34 plus x preamp tubes I would say. Make it 70µm and a 2mm trace will pass 10A at 30°C. Still, I would always mount power tubes off board direct to the chassis, but due to stability reasons of the pcb.

Overall, it's a matter of mechanics and not sound. But what do guitar players know (as in: non-technically minded musicians), for them ancient stuff is always better of course. The point is not what the amp is built on, but what normally goes along with it: pcb = mass produced, cheaper components, etc.; ptp/turret/eyelet board: for the most part built by hand by someone/a company that maybe cares about more than profit maximisation.
Mind you, by now there are amps built on eyelet boards from China.

haven't read all the comment's but, for me as a service tech for a backline company i hate working on tube amps where i have to completly take it apart to replace a single component.

Take for instance a fender twin. if one of the caps goes bad on a fender 65 reissue i have to get the chassis out, unscrew all the screws for the pcb sometime undo tie wraps, hot glue and idc connectors and skew the pcb so i can barely reach underneath with my iron and hope i don't do any damage to the pcb. On an old silverface of ptp blackface i just take the chassis out, solder or just cut the old component out and solder in a new one.... Job done.... 

i understand that when mass producing these amps it's easier to just use a pcb and have a pick n place machine do all the work but it doesn't make any sense in a service point of view. Ampeg (SLM and later) amps are my worst nightmare in doing servicing on and we own at least 2 or 3 dozen of those.....

greetings,

Thomas

Nostagia for the " good ol days " of Fenders & Marshalls  when there was not the exact science of price point
bottomline profit marketing .
In one the the Boogie white papers , or whatever they call their propaganda Randall smith claims they take into
consideration the capacitance from the size of traces and where run on the pcb's

okgb said:

In one the the Boogie white papers , or whatever they call their propaganda Randall smith claims they take into
consideration the capacitance from the size of traces and where run on the pcb's

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Without skewing my own thread in a strange place, I can legitimately say that a Mesa Boogie Mark IV is the sloppiest most messy inside i have ever seen on any guitar amp period. I mean its a rats nest.  Search-eth thy google image of a Mark IV and this point will be proven.

Volker,

You have illustrated my point,

A 35µm copper trace of 3mm width will heat to 30°C at 8A current. Good enough for the heater demands of the run of the mill amp with four EL34 plus x preamp tubes I would say. Make it 70µm and a 2mm trace will pass 10A at 30°C. Still, I would always mount power tubes off board direct to the chassis, but due to stability reasons of the pcb.

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The inside of an amp is usually reckoned to be around 40C ambient, so your 30 degree tracks are on top of that.  Running micron thicknesses of copper foil at 70C plus is not good for longevity.

Hobiesound is dead right and the problem goes right across the engineering industry.  Everything today is made for fastest production, with servicing right at the bottom of the priority list.

Germany is one of the greenest countries in the world, with P2P you could virtually service indefinitely, ever seen the state of a track after you've tried to replace a component more than once?  PCB's are a left-over technology from the planned obsolescence "throw-away society.

DaveP

http://forum.grailtone.com/viewtopic.php?f=27&t=44411

Standard FR4 is specified with a maximum operating temperature of up to 115-140°C. I haven't seen any derating curves concerning the longevity though, a quick search didn't reveal anything. I hope I remember to ask the pcb guy at university next time I stop by. Anybody know more about that?

In an economy, that depends on growth year after year, products that last forever are simply not desirable. That feature of course comes with a price tag most people aren't willing to pay anyway. And what would a ten year old boy do with such an amp he cannot afford in the first place? He plays it a few years, stashs it in the cellar and will ultimately throw it away, so why go premium. Most buyers will never go on tour or play live. PCBs are just the result of producing cheap goods for the masses. Everyone else is free to spend some more on something that can be trusted further than one drop to the ground or is better serviceable. Still, with a quality pcb with complete solder mask and plated through holes, I've never had any track lifting issues, I only know that from older boards.

The rules of "Tone" for guitarists:

1.  Older is always better.
2.  Hand made is always better.
3.  Obscurity sounds better (ever hear a 1940's Teletubby 4AQ7A tube in a phase inverter?  To die for...)
4.  High price sounds better.
5.  "American made" sounds better.
6.  Rarity sounds better (preferably prototypes or one-offs, but <100 limited editions are acceptable).
7.  None of the above matters because "Tone" is entirely in the player's fingers.