Point-to-point wiring or turret board?

[chickenPlucker]

Are there any practical reasons to wire point-to-point from one component to the next as opposed to a neat layout on a turret or eyelet board?

I've read some believe it gives a cleaner signal but is there any solid, physical evidence to support that claim. If it is so, why aren't more amps wired that way. I assume it is not cost effective for mass produced amps, but boutique amps could for what they charge.

Also, is there any advantage to placing the power supply caps/resistors on a board seperate from the signal components?

[briane]

read around...youll see the general consensus is to have separate grounds for power and pre-amp, but the components can be on the same board. I, like others, have wired noise free with a single buss ground, but it does require the component layout follow the 'gods word of grounding'.

I think point to point would be messy, but some here have done it with great results...the downsides...probably more difficult to tweak by tryiing various components, and remember those big resistors can get hot, so I like to have those on a board. I have not heard any of the claims that it would a cleaner signal, and if so why wasnt the dum-man doing it?

Plus a board just looks cool.

[loyjdockery]

I think point-to-point has been marketed as an advantage to circuit boards, not necessarily as an advantage to turret boards. I don't think there is any difference you can hear between the two, assuming both are laid out correctly. I personally like the look and simplicity of using turret boards.

[Alexo]

My thoughts are that while point-to-point gets you potentially shorter lead lengths and possibly less electrical interference and/or capacitance between components since they will be less on the same horizontal plane, it comes out looking terrible, is difficult to trace the circuit, very difficult to replace components and unless you are really careful and good at it, it could cause just as many problems as it could solve.

Having said that, in really simple circuits, like a little single-ended stereo or maybe a champ or something, going point-to-point tends to work out just fine and a turret board is almost pointless, as long as you are using a cap can for the electrolytics, I would never run the filter caps ptp, just seems too risky to me.

[chickenPlucker]

I just found this: http://www.geofex.com/Article_Folders/p ... -to-pt.htm

It seems to explain the physics fairly well.

[Merlinb]

I've read some believe it gives a cleaner signal but is there any solid, physical evidence to support that claim.

That only holds true for hifi amps. For guitar turret board is preferred because we tend to use use more components so it's harder to actually arrange a P to P design, and because we like to tweak components a lot, which isn't easy to do with P to P.

[Geek]

Hi,

One good reason to avoid point to point is guitar amps seem to be made to be modified. Try that with point to point, especially for the inexperienced.

After speaking with some guitarists, researching for a new guitar amp startup company, point to point would be at least one nail in the coffin.

Cheers!

[candh]

Hi,

After speaking with some guitarists, researching for a new guitar amp startup company, point to point would be at least one nail in the coffin.

Cheers!

Like a Carr.......

[playazinc]

PTP is much quicker and if you have some experience in doing it right can be quieter in terms of humm than turret construction.

I’ve knocked out some big and complex amps in 2-3hrs doing PTP.

That said, I would never do an amp intended for sale PTP. It just looks messy and most buyers don’t exactly appreciate it.

[Phil_S]

Terminal strips work just as well as boards, but without the board. Cheap and very flexible, too. I wouldn't go PTP in a guitar amp unless maybe I was trying to shoehorn a Champ into a pedal box. PTP is messy and probably hard to trouble shoot.

[benjoi]

I built a P1 point to point and I absolutely dread working on it. If anything goes bad it's very hard to trace down, but it was fast and cheap to build. It is very quiet though it is extremely messy looking. A friend of mine looked at it and said it looked "dangerous" (I took it as a compliment.

[particle]

I was given a piece of advice a long time ago from someone old enough to know what CQD and QRT meant...

1. If you have to use a tag strip or terminal board, you've completely failed in the design of your point to point layout.

2. If you use a turret layout board, you're never ever going to get serious about anything you're doing.

3. If you use any kind of mechanical layout and conductance aid (such as a PCB), then you're going straight to h*ll.

This all came as a bit of a shock at the time as shiny new transistors were the in thing.

A few years later, I had the opportunity to make a point to point layout without turrets or tags from surface mount components using a microscope and tweezers.

And that's all I have to say on the subject.

[Francis_Vaughan]

I was given a piece of advice a long time ago from someone old enough to know what CQD and QRT meant...

Gosh, doesn't that bring back memories. Perhaps QRO sums up amp building.

The point here is that for RF circuits the sort of layouts we are used to with turret boards would be totally unacceptable, and indeed would almost certainly simply not work. Point to point isn't just about the shortest path between components, it is about the 3D relationship, and control of the inevitable parasitic coupling between components. Be thankful you don't have to worry with inter-stage screens and feedthrough capacitors.

This remains an important issue in many areas of electronic design. HiFi amp design is very influenced by the exact form of PCB design. Digital designs are crucially dependant.

Guitar amps are perhaps one of the few areas that seems to get away with pretty low amounts of care. The gains and bandwidths are so low that mostly there is little to go wrong. Chasing the last vestiges of layout induced distortion not exactly part of the brief. Simply avoiding instability and hum mostly covers it.

[chickenPlucker]

Thanks for all the wisdom. What I learned:

Point-to-point is best suited to experimentation, while turret/eylet boards are preferred for final implementation of design.

Boards provide solid support for heavier components thereby reducing stress on solder joints.

Understanding where problems can arise (such as parasitic capacitance)will help devising a board layout that promotes a clean signal path and is easy to troubleshoot.

Point-to-point can and should still be used for components soldered to valve sockets and pots as these provide a solid support for connections.

[tunghaichuan]

I guess I'm in the minority here.

The first amp I built was a 5F1 champ circuit, laid out on terminal strips. It took me about three days to assemble it. It was a major PITA and it never worked right. There was some parasitic oscillation going on that I could never track down. It was a real rat's nest inside.

The second (and all subsequent) amps I've built have been on eyelet boards. The second amp I built was a 5F2-A tweed Princeton circuit and it took me only one day to completely wire it. It worked and sounded great. It was much neater than my first amp.

Having said that, PtP is a real art form. When done well it is beautiful.

Here are some Japanese hifi amps wired PtP (schematics included):

http://www2u.biglobe.ne.jp/~tossie/cont ... 10106.html

I wish I could wire amps like that.

tung

[zaphod_phil]

Altogether, now: "Turret boards and eyelet boards ARE point to point assemblies."

Conceptually, that's true - and the two terms are also used interchangebly for marketing purposes. However, leaving that aside, while there are similarities, in the electronics engineering world the two terms are conventionally used to describe somewhat different forms of construction, with different pros and cons. And it's got nothing to do with acid-fuelled logic.

True PTP wiring used to be favored in radio frequency work, where it really is critical to have short connection lengths, since every piece of wire acts as a small antenna. Apparently the hifi/audiphool community also seem to think that short lead lengths are critical, but I reckon their logic really is acid-fuelled! With true PTP wiring, components and leads are stretched directly between socket pins, as well as transformer and cap can terminals, with the occasional little piece of tagstrip here and there. Thick self-supporting bus wires are often used, and connecting wires tend to be solid cored, so they will hold their shape when bent. Often it's a 3-dimensional construction, while board-based construction is more 2D.

Here's what true P2P looks like - http://i114.photobucket.com/albums/n267 ... DC30-2.jpg This type of wiring takes a lot of skill and practice to do well - it's really a form of master craftsmanship as much as electronics engineering. Unless done very carefully, this form of construction can be more prone to noise and hum issues. Like Tung says, P2P construction when done well, is something really beautiful, which will work very well. However, you do see quite a few fugly messes as well, like some early AC30s. In general, this kind of wiring can be real difficult to do mods on, due to the way leads are often twisted together before soldering for rigidity, or when components are mounted behind each other.

There is another form of construction, which lies between true P2P and board construction, which sometimes also gets mistakenly called point-to-point. In this you place two rows of tagstrip opposite each other, and solder all the componenets between them, just like they were being soldered to turrets or eyelets. Here are a couple of examples:
http://members.shaw.ca/ronotera/PreampSection.jpg
http://mhuss.com/AmpInfo/images/SunnSoradoGuts1.jpg

As can be seen this is a 2D form of construction, and is actually not too different from how you would build using a turret board or eyelet board, except there's free air underneath the components. This approach is handy, as you don't have to construct a board before you start soldering components, and it's quite easy to work with for mods.

My general preference is for boards, since they generaly offer a good way to produce a tidy and electrically quiet build, that is easy to debug and mod, as well as impress people with.

Point-to-point is best suited to experimentation, while turret/eylet boards are preferred for final implementation of design.

No, its the other way round.

Boards provide solid support for heavier components thereby reducing stress on solder joints.

Debatable. An experienced wireman will take care to mount everything in a mechanically very sound way. There's been a lot of military radio equipment built this way in the past, that's very rugged.

Point-to-point can and should still be used for components soldered to valve sockets and pots as these provide a solid support for connections.

I would say "can and may be used". Apart from certain things like grid stopper and screen resistors, there's no rule saying that everything possible should be soldered onto the socket pins or pots.

Some further reading:
http://www.aikenamps.com/PCBorPTP.htm
http://www.mhuss.com/AmpInfo/

[morcey2]

There is another form of construction, which lies between true P2P and board construction, which sometimes also gets mistakenly called point-to-point. In this you place two rows of tagstrip opposite each other, and solder all the componenets between them, just like they were being soldered to turrets or eyelets. Here are a couple of examples:
http://members.shaw.ca/ronotera/PreampSection.jpg
http://mhuss.com/AmpInfo/images/SunnSoradoGuts1.jpg

As can be seen this is a 2D form of construction, and is actually not too different from how you would build using a turret board or eyelet board, except there's free air underneath the components. This approach is handy, as you don't have to construct a board before you start soldering components, and it's quite easy to work with for mods.

I've got 1 build done that way and another one started:


http://mcorey.dsl.xmission.com/P1ex/p1ex_guts_1.jpg

that's a p1extreme. Not real beautiful, but it works very well. It's much quietier than I was expecting.

http://mcorey.dsl.xmission.com/18Watt/1 ... utless.jpg

That's a lite IIb discussed in another thread. I am much happier with the strips used in this one. I bought out the entire stock of our local electronics shop. All 4 strips.


Matt

[teletroy]

Here's my 36 watt trem


I had to use 4 tag strips because of how the chassis was laid out.