Do modern guitar amp PCBs still look like they were designed in the 1980's?

[e100]

I went searching for pictures and couldn't find any that looked modern.
Lack of competition and innovation perhaps?

Mike

[mtdoc]

I went searching for pictures and couldn't find any that looked modern.
Lack of competition and innovation perhaps?

I suspect how the PCB looks is less important to the non-engineer end user than how the amplifier sounds.

[danmcb]

they are very often single sided boards - for cost I guess - and the tech hasn't moved on much, for the most part, indeed.

[Zero999]

I'd be surprised if guitar amplifiers have changed much since the 1980s. There are still some designs in use from the '50s and 60's.

[AndyC_772]

I've had a little bit of professional involvement here.

From what I understand, customers for this type of product have expectations regarding the aesthetics of a PCB, and a subconscious expectation that if it looks "good", then it'll sound good too.

"Good", in this context, meaning "in line with the customer's expectations of how this type of equipment should look".

There's no science here, though. A small PCB made with surface mount components and a ground plane will pick up less noise than one made with through-hole parts on a single sided board. In objective performance terms, it's simply better, but that doesn't mean it's what the customer actually wants.

Subjective neatness, and similarity to other products with a good reputation, are really important in this highly conservative part of the industry.

[langwadt]

musicians can be strange bunch, on par with audiophools. If something doesn't look, feels and is preferably made with "vintage" parts and designs it doesn't
"sound right"

[BradC]

Most amps don't have their boards exposed and I've never met a guitarist with the slightest concern about anything other than how it sounds at a volume level that makes the sound guy scream "turn that fucking thing down or I'll put a knife through the cone" (which incidentally would turn it into the ideal amp to play any Dave Davies Kinks stuff).

In general, amps have a large control surface with more than a few knobs. A large single sided board with everything mounted on it is a crapload cheaper to build than a small dense and clever board with a thousand wires out to the pots, or sub-boards with ribbons between them.

Like all good engineering, guitar amps are made as complex and "innovative" as they need to be, and no more. That happens to make them easier to fix and mod, which is a nice aside.

[CJay]

I've had a little bit of professional involvement here.

From what I understand, customers for this type of product have expectations regarding the aesthetics of a PCB, and a subconscious expectation that if it looks "good", then it'll sound good too.

Wot he said ^^^^

I've repaired a good number of guitar amps in the past and have 'rescued' amps that would have been a disgrace to my bin but the owners had some weird almost audiophool attachment to them.

I have had clients inspect the PCB (only once or twice) when buying a second hand amp, not because they had a clue about the electronics but because they wanted to see the 'quality'.

Most fell into the Nigel Tuffnell 'it goes to eleven' realm.

 

[oldway]

According to my findings, it is not recommended to use printed circuits boards with tubes for the following reasons:

- strong heating of the solders of the socket of the tubes and of the power resistors, which causes bad solders. The situation has worsened since the use of lead-free solder.

- high voltages in the circuits, especially in the output tubes .... there is a high risk of arcing and carbonization of the printed circuit.

The use of printed circuits boards causes a great reduction in the reliability of the amplifiers.

[BradC]

The use of printed circuits boards causes a great reduction in the reliability of the amplifiers.

Somebody better tell Mesa Boogie they've been doing it wrong all these years!

[TheUnnamedNewbie]

According to my findings, it is not recommended to use printed circuits boards with tubes for the following reasons:

- strong heating of the solders of the socket of the tubes and of the power resistors, which causes bad solders. The situation has worsened since the use of lead-free solder.

- high voltages in the circuits, especially in the output tubes .... there is a high risk of arcing and carbonization of the printed circuit.

The use of printed circuits boards causes a great reduction in the reliability of the amplifiers.

This sounds like typical audiophool-bs to me. PCBs have be used in applications like amplifiers and other devices where components get hot for ages now, with no difficulties. High power amplifiers for stage work/monitors, that push out a lot more power and have to hold up to a lot more abuse, have been using PCBs for a long time.
More related examples: I also believe that some of the most "workhorse" guitar amplifiers, like a Mesa Triple Rectifier, or a Peavey 5150, etc, have used PCBs since day 1, and they are said to be among st the most reliable bits of kit out there. Of course, you might put the tubes themselves in sockets connected through wires not just for reliability but for maintenance and aesthetic reasons (so they are easily accessible for replacement and they look nice through the amplifier.)

On the arcing topic: You are "only" dealing with <1kV here. PCBs have been used in other applications like CRT drivers, laser drivers, .... That deal with far higher voltages. Especially given the amount of room in guitar amplifiers (they are stupendously huge, often half-empty boxes because they have to "fit" the speaker cabinets they sit on) this seems like a non-issue.

[filssavi]

According to my findings, it is not recommended to use printed circuits boards with tubes for the following reasons:

- strong heating of the solders of the socket of the tubes and of the power resistors, which causes bad solders. The situation has worsened since the use of lead-free solder.

- high voltages in the circuits, especially in the output tubes .... there is a high risk of arcing and carbonization of the printed circuit.

The use of printed circuits boards causes a great reduction in the reliability of the amplifiers.

First if you have arcing in a 600V PCB trace (the operating voltage of KT88's is 560V as per datasheet) you might want to fire who layed out said circuit board for his gross incompetence

Second don't fault PCB for the amp producer greed if they where so concearned with solder thermal  cycling  issues (which think are non existent in good designs) they would use the more expensive press fit technology

[oldway]

In a push pull configuration, normal peak working voltage can reach twice the operating voltage ....
If the amplifier is working with no load, the anode voltage can reach several KV's

I repaired a lot of tube gears with pcb's (amplifiers, b§W and color tv's, scopes, ...) and the first thing to do is to look for bad solders at the tube sockets....

In tube amplifiers, whe never relied upon solders to ensure contact between the socket and the components.
One of the first rule was to ensure contact by mechanical fixing ....

Faylon Studio 40W

[frozenfrogz]

https://www.thegearpage.net/board/index.php?threads/the-amp-guts-appreciation-thread.334977/

[danmcb]

somebody explain to me how a TV can have 20kV on a circuit board with no arcing,  but a guitar amp has problems at 250V.

There are a few exceptions. Vox have a line of amps with some really good digital modelling for all kinds of classic vintage amps (with subtly changed names) and they sound really good, at least to me. Also there is a company (Marshall spinoff I think) that do some really neat stuff. I forgot the name.

but yes, it is a really stupidly conservative industry. I have experienced this first hand.

[cowana]

somebody explain to me how a TV can have 20kV on a circuit board with no arcing,  but a guitar amp has problems at 250V.

A slight generalisation, but in most TVs the 20kV never goes near the PCB. The HV is generated by a flyback transformer, which outputs the HV directly into a heavily insulated lead connecting the flyback transformer to the CRT.

[Fungus]

According to my findings, it is not recommended to use printed circuits boards with tubes for the following reasons:

- strong heating of the solders of the socket of the tubes and of the power resistors, which causes bad solders. The situation has worsened since the use of lead-free solder.

The amps on this page don't have the tubes on the PCB, they're on a metal bracket with wires going to the PCB.

https://www.thegearpage.net/board/index.php?threads/the-amp-guts-appreciation-thread.334977/

- high voltages in the circuits, especially in the output tubes .... there is a high risk of arcing and carbonization of the printed circuit.

Weird how nobody is seeing any. I guess the "risk" isn't so high after all.

The use of printed circuits boards causes a great reduction in the reliability of the amplifiers.

So why are they still using designs from the 1960s?

[Fungus]

... happens to make them easier to fix and mod, which is a nice aside.

I'm sure this is a big part of it. Replacing capacitors, etc., has been a thing among audiophools for decades.

Also: Valves and oversized components look the part!

There's no way surface mount on a tiny PCB could ever produce a decent sound. The electrons will be strangled.

[HackedFridgeMagnet]

The electrons will be strangled.

"Strangler", do they make that guitar pedal? If they don't they should.

[oldway]

The appreciation of the quality of a sound is something very subjective and soms very strange.

In my opinion and that of several of my friends, it is not the most perfect amplifier that sounds the best ....

This old ARTEC tube Hi Fi stereo amplifier of the 60s sounds better than my Marantz 2285B....

And yet, This ARTEC has a measured THD of 3%...

[oldway]

And no pcb at all....

[e100]

https://www.thegearpage.net/board/index.php?threads/the-amp-guts-appreciation-thread.334977/

The components on those boards look like they are deliberately hanging in the breeze to achieve maximum microphonic pickup. Is that the secret sauce that makes a 'classic' sounding amp?

[oldway]

https://www.thegearpage.net/board/index.php?threads/the-amp-guts-appreciation-thread.334977/

The components on those boards look like they are deliberately hanging in the breeze to achieve maximum microphonic pickup. Is that the secret sauce that makes a 'classic' sounding amp?

Greatest concern with microphonic pickup is with low level signal preamplifier tubes.
Even using special low microphonic tubes as EF86, I often had to select the best of them
I have never had problems of microphonic pickup with other components.

[e100]

I've had a little bit of professional involvement here.

From what I understand, customers for this type of product have expectations regarding the aesthetics of a PCB, and a subconscious expectation that if it looks "good", then it'll sound good too.

"Good", in this context, meaning "in line with the customer's expectations of how this type of equipment should look".

There's no science here, though. A small PCB made with surface mount components and a ground plane will pick up less noise than one made with through-hole parts on a single sided board. In objective performance terms, it's simply better, but that doesn't mean it's what the customer actually wants.

Subjective neatness, and similarity to other products with a good reputation, are really important in this highly conservative part of the industry.

How about a placebo PCB that looks like something from the 60's or 70's but is actually non functional. Hidden under one of the electrolytics would be a single DSP doing everything except the PA stage. Could knock a few dollars off the BOM. Target the low end of the market first. There could even be a viewing window with mood lighting like they do with gaming PCs.

[AndyC_772]

No. Never treat your customers like idiots.