Handwired vs machine made

joeyowen

Tbh, if I could have afforded the hand made Kemper I might have gone for it.  I'm pretty sure mine is machine made

giggle

ecc83

martinw said:

ecc83 said:

Sorry chaps do not agree.  And re 'standing voltages'? GOOD practice is to fit drain resistors.

Dave.

It's ok to disagree.

As for GOOD practise, it's good practise to NEVER rely on a single safety feature, such as drain resistors.

You'd never assume the drain resistors hadn't failed, would you? You'd still check with a meter?

Well, I do anyway. In which case it's not as if drain resistors make everything ok, and my argument stands; it's all lethal, all the time, treat it as such. Sleeving only mains is pointless when you take that approach, which is the only truly safe way.

I take nothing for granted, I have handled enough firearms to know that. Safety comes in layers.

If the earth is diss'ed to an amp it does not matter unless the chassis goes live and even then someone has to touch that AND have another path to earth. Similarly we CAN boot IEC sockets and fuse carriers and switches and traff wires can use booted 6mm connectors. With a well designed PCB amp it is possible to have very few  bare high voltage areas. JUST because it is hand wired surely does not mean we DON'T  do all we can? Modern MF 1 watt resistors are very durable, ever tried to burn one out?

You cannot cover for idiots. "Our" stuff has the usual stern warning "NO USER SERVICABLE PARTS INSIDE! And the S1 series carries a warning for techs that the standby function is a bit 'unusual'.  Wish they didn't HAVE to have it!

Dave.

SunDevil

SunDevil said:

To kick this one off...

1) Repairability 
2) Space between components for cooling and to reduce interference 
3) Not having all electrical signals in parallel lines is meant to reduce cross-over noise

4) Tweakability :-) ..much easier to change coupling caps, B+ voltages etc for rank amateurs such as myself on a turret board

Chalky

ecc83 said:

martinw said:

ecc83 said:

Sorry chaps do not agree.  And re 'standing voltages'? GOOD practice is to fit drain resistors.

Dave.

It's ok to disagree.

As for GOOD practise, it's good practise to NEVER rely on a single safety feature, such as drain resistors.

You'd never assume the drain resistors hadn't failed, would you? You'd still check with a meter?

Well, I do anyway. In which case it's not as if drain resistors make everything ok, and my argument stands; it's all lethal, all the time, treat it as such. Sleeving only mains is pointless when you take that approach, which is the only truly safe way.

I take nothing for granted, I have handled enough firearms to know that. Safety comes in layers.

If the earth is diss'ed to an amp it does not matter unless the chassis goes live and even then someone has to touch that AND have another path to earth. Similarly we CAN boot IEC sockets and fuse carriers and switches and traff wires can use booted 6mm connectors. With a well designed PCB amp it is possible to have very few  bare high voltage areas. JUST because it is hand wired surely does not mean we DON'T  do all we can? Modern MF 1 watt resistors are very durable, ever tried to burn one out?

You cannot cover for idiots. "Our" stuff has the usual stern warning "NO USER SERVICABLE PARTS INSIDE! And the S1 series carries a warning for techs that the standby function is a bit 'unusual'.  Wish they didn't HAVE to have it!

Dave.

You pair remind me of the argument between the young trawlerman and the old trawlerman. 

Knowing the dangers of the sea, the young man believes in being an excellent swimmer, practising falling into the sea and what to do if it happens, and having every safety aid in case he ever falls off the boat in a storm, and is therefore can concentrate on what he's doing on the boat when working. 

Knowing the dangers of the sea, the old man has never been in it, knows that if he ever falls off the boat in a storm he will drown, and is therefore always on his guard against falling into it, no matter what he's doing on the boat.

Which is the better safety approach?

ecc83

So, what if the Old Sea Dog falls OB in the harbour?  In ANY case! Sleeved/booted tags LOOK neater!

An ANOTHER thing! We know that it is important to get pros to a HA victim within the hour but in these lean times that is getting increasingly difficult. Does that then mean we should not even try?

Dave.

Danny1969

DJH83004 said:

There is an additional dimension to this discussion around the concept of handwired, these are a couple of amps that I have repaired / serviced in the past, one turret board, one true P-to-P using tag strip. Both well respected builders with great reputation for tone and quality. One amp is a dream to work on the other is a nightmare! But hey-ho you don't buy amps for the benefit of the amp tech     

To be honest both those amps look a pretty easy to work on compared to something like a ENT Savage 120 or similar nightmare
The engineer in me can't help thinking in the top picture that the turret board is too wide and it kind of looks childish to me to see components laid out like that .... I know I'm probably in the minority as that kinda thing is meant to be good in valve amp world
In the bottom picture there's so much room around everything you can literally see where everything going and every component is so big I could probably work on that without my glasses

martinw

Not sure who's who in that story. Perhaps you could enlighten me?

Sporky

martinw said:

Not sure who's who in that story. Perhaps you could enlighten me?

I think one of you is the sea, and the other is the boat?

ICBM

Danny1969 said:

To be honest both those amps look a pretty easy to work on compared to something like a ENT Savage 120 or similar nightmare

I worked on an Engl recently - can't remember which model - and it was certainly a nightmare. If I hadn't been able to identify and desolder the failed components from above the PCB, let them drop underneath and shake them out of the chassis, then solder new ones on from the wrong side, I would have had to take the whole PCB out, which would have meant unsoldering and ungluing multiple wiring connections. This is the kind of thing that gets PCB a bad name, but it's not a fault with PCB - it's just pure bad design.

ecc83

Sporky said:

martinw said:

Not sure who's who in that story. Perhaps you could enlighten me?

I think one of you is the sea, and the other is the boat?

Right chaps! As I read it, the OSD does not learn to swim nor wear a life jacket because, he reckons going OB at sea is the end, no chance and he is probably right... My defence was, IF he goes into the water in a still pond harbour he will sink like a stone before anyone notices him.

Our electrical safety regs are very conservative and contain a lot of redundancy but I don't think anyone here is proposing we water them down?

Dave.

Plectrum

ecc83 said:

So, what if the Old Sea Dog falls OB in the harbour?

As long has he's not repairing an amp which is plugged into the mains at the time he'll probably be OK Especially if the tide is out

olafgarten

ICBM said:

rico said:

What I don't get however is where there is a handwired and pcb version of the same product - Mad Professor pedals for example. 

Presumably the handwired version costs a lot more, for those buyers who want something more exclusive, and the PCB version is for those who just want the same functionality but cheaper.

ZVex does the same thing.

Don't ZVex also have custom unique painted designs on the hand wired versions? That would justify a price difference. 

darthed1981

Chalky said:

ecc83 said:

martinw said:

ecc83 said:

Sorry chaps do not agree.  And re 'standing voltages'? GOOD practice is to fit drain resistors.

Dave.

It's ok to disagree.

As for GOOD practise, it's good practise to NEVER rely on a single safety feature, such as drain resistors.

You'd never assume the drain resistors hadn't failed, would you? You'd still check with a meter?

Well, I do anyway. In which case it's not as if drain resistors make everything ok, and my argument stands; it's all lethal, all the time, treat it as such. Sleeving only mains is pointless when you take that approach, which is the only truly safe way.

I take nothing for granted, I have handled enough firearms to know that. Safety comes in layers.

If the earth is diss'ed to an amp it does not matter unless the chassis goes live and even then someone has to touch that AND have another path to earth. Similarly we CAN boot IEC sockets and fuse carriers and switches and traff wires can use booted 6mm connectors. With a well designed PCB amp it is possible to have very few  bare high voltage areas. JUST because it is hand wired surely does not mean we DON'T  do all we can? Modern MF 1 watt resistors are very durable, ever tried to burn one out?

You cannot cover for idiots. "Our" stuff has the usual stern warning "NO USER SERVICABLE PARTS INSIDE! And the S1 series carries a warning for techs that the standby function is a bit 'unusual'.  Wish they didn't HAVE to have it!

Dave.

You pair remind me of the argument between the young trawlerman and the old trawlerman. 

Knowing the dangers of the sea, the young man believes in being an excellent swimmer, practising falling into the sea and what to do if it happens, and having every safety aid in case he ever falls off the boat in a storm, and is therefore can concentrate on what he's doing on the boat when working. 

Knowing the dangers of the sea, the old man has never been in it, knows that if he ever falls off the boat in a storm he will drown, and is therefore always on his guard against falling into it, no matter what he's doing on the boat.

Which is the better safety approach?

The young guy.  The old guy works near water all the time and won't learn to swim, he isn't safe at all he's a f**king idiot.

No matter how careful you are shit happens.

Modulus_Amps

Chalky said:

When working on a handwired amp whats the rules and regs these days on fixed mains wiring vs IEC connector /kettle leads, and cloth covered wire vs modern plastic insulated wire?

What do you mean by "working on"?

If building new amps for sale you should really get a hold of the ISO 60065 harmonized standard.
Cloth wiring is allowed if it is treated and meets the other requirements laid out, otherwise it is considered to be bare (Section 8.1)

Actually section 8, section 15 (sockets) and section 16 (flexible cords) covers most of what you are asking.

If repairing then you need to use judgement to either do it the original way or upgrade to current standards.

Chalky

Modulus_Amps said:

Chalky said:

When working on a handwired amp whats the rules and regs these days on fixed mains wiring vs IEC connector /kettle leads, and cloth covered wire vs modern plastic insulated wire?

What do you mean by "working on"?

If building new amps for sale you should really get a hold of the ISO 60065 harmonized standard.
Cloth wiring is allowed if it is treated and meets the other requirements laid out, otherwise it is considered to be bare (Section 8.1)

Actually section 8, section 15 (sockets) and section 16 (flexible cords) covers most of what you are asking.

If repairing then you need to use judgement to either do it the original way or upgrade to current standards.

Thanks - its not for my use, just out of interest of what you amp builders and techs have to abide by when building or working on amps that are old or built 'just like they used to build them'. 

I guess I can't see the advantage of tethered cord over a socket and kettle lead, nor the advantage of cloth over modern insulated wire.

ecc83

"I guess I can't see the advantage of tethered cord over a socket and kettle lead, nor the advantage of cloth over modern insulated wire. "

As far as I am concerned the IEC mains connector was one of THE great inventions of the 20th century as I am sure ANYONE who has had to deal with dangly,tangly fixed cables will testify! It is one of a very few WORLD standards.

It had a painful gestation. There was the 'breakable Bulgin' (2 sizes) which also had very poor cable strain relief. The mains Cannon was good but I understand did not meet certain safety standards?

Then, practically every mnfctr had their own style of mains conn' (I still have some odd ones if anyone has an old Revox or similar) Many were only veeery slightly different from their rivals but just enough to confuse/eff you up!

At the risk of being shot for going OT. Be vigilant chaps that imported gear has UK mains plugs on the IEC lead. They seem to send any old ***t in the box these days and that is illegal. This situation can only get worse now that the t**ts seem to be getting us out of the EU. Shout!

Dave.

ICBM

That’s really the only disadvantage - with it being a global standard, you have no protection against someone importing a US/Japanese-voltage unit, and plugging it straight into the UK/Euro mains with a different kettle lead.

At least with a captive cable you have to be more deliberately stupid before you can do it.

ToneControl

rico said:

Someone asked me this the other day and I couldn’t really come up with the answer that didn’t sound like waffle. 

What would you say the main reason for an amp to be hand wired rather than pcb/machine made is?

Aside from the already-mentioned fact that modern PCB mass-production tends to push designs to be less repairable:

• Heat-management when using valves is frequently handled badly with PCBs: valve bases are often soldered straight onto the main PCB, thus providing massive localised heat injection into several PCB locations. Most hand-wired amps will use chassis-mounts for the power valves and rectifier, if not all the valves. This makes the amp less likely to fail under use and means the valves are less able to push inertial shocks into PCBs during rough handling
• Handwired amps are more likely to have separate controls mounted on the chassis or faceplate, rather than on the main PCB, which reduces chances of shocks or damage on the main PCB
• Generally, hand-wiring is labour-intensive, and therefore expensive. Any company doing it nowadays is less likely to be taking shortcuts elsewhere in the design

For normal modern non-guitar-amp circuits, a robotic component placement system, and automated soldering using paste or wave soldering will be significantly more reliable than hand-assembly, as well as cheaper. WIth amps, there are not many components compared to most kit we now use, hence the opportunity to hand-wire for an extra cost that is not astronomical

ICBM

ToneControl said:

Heat-management when using valves is frequently handled badly with PCBs: valve bases are often soldered straight onto the main PCB, thus providing massive localised heat injection into several PCB locations.

That's true, although as ever the devil is in the detail... valve bases mounted *only* on the PCB with no chassis support do indeed cook the board over time, especially if they're mounted upside down in combos where the hot air will rise through the small gap in the chassis around the valve. (Marshall tried to fix this in the early DSL401 by making the cutout such a tight fit that it wouldn't happen, but the result was that valves with slightly fatter bottles won't go in! Doh.)

But if the valve has a proper chassis-mounted base as well and all the PCB does is provide the electrical connections, it's not a problem - the chassis thermally isolates the valve almost completely from the PCB, even if it's underneath. So you can't necessarily judge an amp as being 'bad' if it has 'PCB-mounted valve sockets' - you need to see exactly how it's done. Preamp valves are almost always fine either way too.

ToneControl said:

Handwired amps are more likely to have separate controls mounted on the chassis or faceplate, rather than on the main PCB, which reduces chances of shocks or damage on the main PCB

Same again. For example Mesa have always stuck to mounting the pots and jacks on the chassis with flying leads, although they're definitely quite unusual in that with PCB amps.

One less obvious problem is that if the PCB is mounted *too* well - especially in several places, eg via the pot bushings and also by being bolted to stand-offs further back - then if the chassis flexes under the weight of the transformers it can crack the PCB. Trace Elliot V8 bass amps for example...

It's actually better to mount the PCB 'lightly', even if it looks flimsy - Mesa do it by using flexible nylon standoffs - or just by the pots with the rest of it hanging off them, since that way it moves freely as the chassis flexes.

You often tend to find this stuff out after years of fixing the same faults over and over. It's perhaps not a coincidence that Randall Smith of Mesa was a repair tech before he started building amps... whereas I suspect that a lot of the designers employed by larger companies don't have that real-world experience.

Modulus_Amps

ICBM said:... whereas I suspect that a lot of the designers employed by larger companies don't have that real-world experience.

Not the ones I know, they would say they had there hands tied.

@Chalky said:

I guess I can't see the advantage of tethered cord over a socket and kettle lead, nor the advantage of cloth over modern insulated wire.

Agreed, there is no advantage to either, in fact I don't sell cloth covered wire as I don't recommend it after seeing a few rot jobs.


Hopefully any builder that builds them 'just like they used to build them' is also taking modern safety requirements into consideration. unfortunately  I know this is not the case and building to exactly match a 1960 amp basically will likely not comply with modern guidelines. If you are ever buying a custom amp direct from the builder you can ask for a Deceleration of Conformance to be supplied, in fact you really should. if they don't know what that is then they likely have not understood the Directives properly and should not be selling electrical goods.

Saying that, there are many good build techniques from the past than can still be used and will help the service life of an amplifier.