Advantages of PTP wiring?

[Cantplay]

I was taught that solder joint should be mechanically sound first. The solder being almostrredundant. This is not possible for PC board.

John

[renshen1957]

I was taught that solder joint should be mechanically sound first. The solder being almostrredundant. This is not possible for PC board.

John

Hi,

I agree, both PTP and turret boards for the most part this is the case. I use the same principle in eyelet boards and tagboards as much as possible.

Best regards

Steve

[VacuumVoodoo]

I was taught that solder joint should be mechanically sound first. The solder being almost redundant. This is not possible for PC board.
John

Yes it is. Dual layer board, plated through holes and component leads bent on the underside. The biggest danger in manual soldering a densely populated PCB is leaving a pad unsoldered. Such board might pass both electrical and vibration tests due to mechanical strength of the bent lead through plated hole.

[eniam rognab]

this is one quality thread. in one of my 'lectronics classes today we were discussing different circuit types so i pulled up this thread.

everyone loved the purty pitchers and renshens post was read aloud for all

thanks everybody

[martin manning]

Did any interesting discussion around the subject occur?

[eniam rognab]

Did any interesting discussion around the subject occur?

yeah definitely! alot of my class mates had never seen anything but a pcb or a breadboard circuit. those pictures really grab your attention and provide inspiration! we started talking about microcontrolled led cubes and the trend of making free form 3D circuits.

most of my fellows dont pay that much attention to analog circuitry, opting for the microprocessor things. but those same guys are now planning audio amps now

copy cats

thanks tag!

[Reeltarded]

https://tubeamparchive.com/viewtopic.php?t=22561

Fix or burn in an open pit; this is the question.

[beasleybodyshop]

https://tubeamparchive.com/viewtopic.php?t=22561

Fix or burn in an open pit; this is the question.

Man that is rough, cool photo of the tubes about to implode.

Is it just me or does it use really funny lookin square capacitors? are these the ones that were designed to be machine-stuffed onto the circuit?

[rp]

I'm usually the advocate around here for ptp. Years ago I built a few amps pre internet (ie no instant help) and had 2 out of 3 amps squeal and no way to figure it out as I just jumped into the deep end knowing nothing, having just the the Pittman and Weber books, and started soldering away. Talked to a NYC tech Matt Wells, who a friend directed me to, and he showed me an open Matchless and told me if you are unsure what you're doing PTP is a pretty safe way to go. I went home started punching drilling an soldering and by bleary eyed dawn I had most of this 5F6A done - I didn't even draw it out before hand, just felt inspired and went w/ the muse.

It worked right off the bat and sounded insane. The elation from that carried me for quit a bit. If you're interested I have most of my ptp amps on TAG. Unfortunately my 2 letter handle makes it hard to search me.

I think ptp amps sound a touch brighter and clearer and direct in a good organic and holoistic way - more immediate, more present. I keep doing it since I like the pre-planning involved and like to march to my own drummer rather than just copy known board layouts. As I can't design circuits I keep myself entertained w/ the feng shui part. I now first rigorously draw everything out 1:1 scale to check parts' lead lengths to make sure I can bridge sockets to pots etc. I think hoping for repeat magic of that first build would be pressing my luck.

I would never build this way if I sold amps, unless someone insisted on it. Giant PITA to repair stuff, or just fix a mistake, or play around w/ mods. Sometimes you must trash a few resistors or caps to get to some buried part. Sucks when you must trash a nice 1W NOS A-B. You can wind up with a lot of heat too to get something loose, even with sinks, and trash some nice old caps, if you are using nice old caps. I've ripped out whole sockets in fustration. PI's are a big PITA ptp.

Build a ptp champ - then decide how much fun you had, or not, and take it from there.

[beasleybodyshop]

I'm usually the advocate around here for ptp. Years ago I built a few amps pre internet (ie no instant help) and had 2 out of 3 amps squeal and no way to figure it out as I just jumped into the deep end knowing nothing, having just the the Pittman and Weber books, and started soldering away. Talked to a NYC tech Matt Wells, who a friend directed me to, and he showed me an open Matchless and told me if you are unsure what you're doing PTP is a pretty safe way to go. I went home started punching drilling an soldering and by bleary eyed dawn I had most of this 5F6A done - I didn't even draw it out before hand, just felt inspired and went w/ the muse.

It worked right off the bat and sounded insane. The elation from that carried me for quit a bit. If you're interested I have most of my ptp amps on TAG. Unfortunately my 2 letter handle makes it hard to search me.

I think ptp amps sound a touch brighter and clearer and direct in a good organic and holoistic way - more immediate, more present. I keep doing it since I like the pre-planning involved and like to march to my own drummer rather than just copy known board layouts. As I can't design circuits I keep myself entertained w/ the feng shui part. I now first rigorously draw everything out 1:1 scale to check parts' lead lengths to make sure I can bridge sockets to pots etc. I think hoping for repeat magic of that first build would be pressing my luck.

I would never build this way if I sold amps, unless someone insisted on it. Giant PITA to repair stuff, or just fix a mistake, or play around w/ mods. Sometimes you must trash a few resistors or caps to get to some buried part. Sucks when you must trash a nice 1W NOS A-B. You can wind up with a lot of heat too to get something loose, even with sinks, and trash some nice old caps, if you are using nice old caps. I've ripped out whole sockets in fustration. PI's are a big PITA ptp.

Build a ptp champ - then decide how much fun you had, or not, and take it from there.

Very cool rp. It looks from your photos that placement of the ground buss is critical.

[xk49w]

Right now I'm sort of preferring double sided PCB, plated thru holes with turret terminals for external connections.

I'm sure I have posted this before but I like looking at the pictures
[img681]https://lh6.googleusercontent.com/-2z7O ... _close.JPG[/img]

I don't have a final shot - this will give you an idea. The turrets are soldered to the top and bottom pads. If it were done to military specs (it wasn't) there would be an additional wire for each turret, soldered between a pad in the active trace to the bottom turret location. The idea is that if vibration got so bad that the turret broke free from the hole into which it was soldered, the wire would still maintain the connection between the external circuit and the on-board destination.

[img684]https://lh5.googleusercontent.com/-_kL9 ... assy_4.jpg[/img]

[Kagliostro]

Also Vox used that system

K

[rp]

Very cool rp. It looks from your photos that placement of the ground buss is critical.

In that it also acts like a terminal strip, placement is critical if you want to keep things compact and short. Short is key as you want to bridge things using as few as wires as you can get away with. BTW avoid most modern resistors and caps w/ very short leads. You ground one end of the buss to the chassis, at the input, and you connect to the buss grouping the stages progressing from input to output, and connecting the relevant power cap to its stage on the buss, if needed with a wire run. If the buss is very short like the Champ you can skip the later and just group the filter caps, doesn't seem to hurt anything. What's nice is you are basically soldering up the schematic, left to right, as your layout.

xk49w: nice boards. Only issue is you must take them up to unsolder, likely easier than ptp but not as easy as straight turret boards unless you use molexes. In that pre-amp your boards free up really easy which is thoughtful.

[teemuk]

Cons: The majority of Guitar Amp PCBs are vary from barely adequate to very poor.

Maybe. Point is, your remarks should be viewed under that light: Applying to BAD designs only.

However, let's adress the very same issues when the design is a good one.

Printed circuit boards almost always have the components on one side and the solder joint on the other, which means you must remove the entire circuit board to change one component.

Nope. For example, my fairly inexpensive (as in cheaper than most guitar amps) Pioneer domestic hifi stereo amp has removable top and bottom panels so the solder side of the PC board is as easily accessible as the component side. ...Oh, it also had silkscreened component designations on both sides of the board.

Of course, if you design things to make dissassembly process difficult then the dissassembly process will be difficult. However, PC board doesn't mandate that. ...cheap manufacturing, however, might.

I don't know if a PTP rat's nest with no wire slack whatsoever and components piled on top of other components is any easier to repair. There are other cons too in PTP: Usually you can't refer to schematics as easily and quickly because there are no silkscreened component designations and you basically have to map out the entire circuit to find which component is which. Replacing one component tends to require that you desolder it off from a messy pile of other components and then perform the whole routine again to solder the replacement component on place. The cool looking heat shrink and all wiring insulation usually burns nastily in the process and you have to work in very tight spots because the components are hardly ever layed on plane but just "rat's nested" to an ugly spaghetti ball that you constantly have to lookout when you stick a soldering iron in.

Too much heat on a PCB and the trace will lift off the board. That's an easy mistake to make that's hard to fix.

It's actually pretty easy to fix. The mistake is also made only if you don't have proper skills working on PC boards.

Much harder to add parts, mod, or to repair broken connections (traces) between components.

I wouldn't say so. You can always "rat's nest" them just like with ordinary PTP builds or just use the traces as solder pads. I have done this many times with prototype builds that suddenly required more components to work properly when you moved from paper to actual real-life circuit. It doesn't look as neat and professional but is super easy even with PC boards.

Although a PCB will last a lifetime as a bedroom amp for the occasional player, the typical PCB amp with a working musician lasts a few years.

If it's a poorly built PC board and/or an abusive musician using the amp. On the other hand, PC boards were sent to space already in 60's and they held up excellently. I could think of several other demanding tasks where PC boards are used and that have no considerable issues with reliability due to that. Besides, I really don't know if the poorly built PTP "rat's nest" would last any longer before vibrating apart. At least it was a pretty common issue in the old days and one of the reasons why people moved to using turret, terminal or PC boards.

[Phil_S]

Amateur builder here...a few thoughts. I've built on a turret board and I've done PTP. Real PTP (maybe a bit of cheating with tag strips for long bridges) wire runs can be either eliminated or kept extremely short in most cases. This does an end run on lead dress issues. I like it because it is so organic. Basically, you can build it from the schematic and with just a bit of ingenuity, you can place the sockets and other components so they just flow together. I imagine PTP is hard to do unless you understand some of the basic rules of construction, which are often learned by making turret/eyelet board amps first. All that said, a turret board is much more linear in its design, making certain trouble shooting and parts swapping easier.