Advantages of PTP wiring?

[beasleybodyshop]

Pros? Cons? Seems to me that PTP is more susceptible to broken solder connections through speaker vibrations. Someone educate me.

[Blackburn]

Some amps like to be PTP more than others. Many with 12AX7s don't seem to care too much, particularly lower gain models. Take a 5B6 for example, with those octals in the pre. Huge difference in noise PTP vs using a board. The reduction in lead wires is a big deal in that amp. I know. It may just want to eat you alive if it's not PTP. I've found that PTP builds actually put up with vibrations better, as long as your joints are strong.

[printer2]

Don't know why a board would cause more noise than p-p as long as you use one that is non-conductive. P-p is no better for lead dress than a board layout, if you do either one haphazard you will end up with problems.

If you have a good mechanical connection of the wires you should not get broken solder connections.

[tubeswell]

Depends how much 'slop' there is in your parts. Sockets with loose pins are sloppier. Work-arounds (like using a lead wire to the socket pin) can overcome that.

Good PTP not only looks pretty, but is solidly build to last several lifetimes, and is easy to repair. On the 'con' side, it requires planning and care in the layout and execution. Some people find that having to think about thinks like that is too much hard mental work. To me its part of the enjoyment of the whole creativity thing. YMMV

(None of the following examples are mine BTW. They are just a few examples of what I work consider to be various stylistic/artistic interpretations of good PTP) Again YMMV

[img:654:351]http://www.aikenamps.com/DR504.gif[/img]

[img:800:600]http://www.amparchives.com/album/Energy ... c14f_3.jpg[/img]

[img859]http://www.bluebirdmusic.com/JadisInside.JPG[/img]

[EtherealWidow]

And then there's always this dude

http://www.bcaudio.com/construction-details.html

[beasleybodyshop]

Wow. Talk about motivation to step up my game.

[tubeswell]

And then there's always this dude

http://www.bcaudio.com/construction-details.html

Exquisite

[img:400:600]http://www.bcaudio.com/BC-Audio_Amplifi ... 1_guts.jpg[/img]

[EtherealWidow]

I mean... turrets are cool too...

[Kagliostro]

One other example

[img767]http://i497.photobucket.com/albums/rr33 ... bad22a.jpg[/img]

if you search for Darryl here

http://www.guitargear.net.au/discussion/index.php

you'll find a lot of guitar amps build this way

K

[Structo]

Point to point can be great or it can be your worst nightmare.

In other words you have to do it right or you will end up with a howling mess.

It seems as if a lot of the cheaper amps from the 50's were PTP, probably as a cost cutting measure since you aren't using a board.

A great deal of them look terrible but that can be deceiving.

It's all about where you put what and and observing good layout practices.

[Blindog]

I remembered this interesting article on PTP from R.G. Keen:

http://www.geofex.com/article_folders/p ... -to-pt.htm

Mark

[Gaz]

I don't know, but nowadays, it's things like these really impress me since they're so beyond my level of engineering, and without being mass-produced crap.

A lot the boutique true PTP stuff seems like its more about the gut shots than the utility of he actual amp. I think the Komet amps are a nice balance between beauty and serviceability without going over the top (except on the price). Carr may be a good PTP example, and Suhr or Aiken for hybrid construction.

I am a firm believer than no one construction method is fundamentally better than any other.

[renshen1957]

Pros? Cons? Seems to me that PTP is more susceptible to broken solder connections through speaker vibrations. Someone educate me.

Hi,

True Point to Point wiring was used in some of the then upscale (read expensive) Hi Fi Stereos (Fisher, etc) into the 1960's (some brands with higher quality parts, and some brands with not so high quality) as well as cheap OEM guitar amps for Sears and Montgomery Wards (or Monkey Wards as we used to call it).

The original Matchless amps were point to point using terminal strips and Garnet Amps used the method from the 1960's onward.
My friend's Matchless DC 30 dropped of the back of a pick up truck. It gigged immediately afterwards all night without a hitch.

Point to Point:

Pros: Once properly designed, assembly is relatively fast. and the amp is very, very tough and rugged. Zero to near Zero Parasitic capacitance between components.

Cons: , repairs usually very slow, Component relocation very difficult if not next to impossible. Harder to modify or hot rod board.

Circuit Cards, Tagboard, and Turret boards are mistakenly called point to point. Hand wired would be better, but some PCB are hand stuffed, hand soldered, and for some parts hand wired (if only a few pots). All share similar virtues and drawbacks in different proportions.

Circuit Cards (ala Fender Tweeds through the Silver Face)

Pros: Easier to repair than PCB or PTP. Easier to design a board. Faster assembly than PTP. The option to place the components optimally, to fine tine a circuit. Almost indestructible, can be soldered with little concern as to damage,

Cons: Depending on board material, can be problematic with the old wax-impregnated cardboard board becoming conductive. Not so much a problem with Fiberglass other material. Some Parasitic capacitance between components, worse with smaller modern components crammed into smaller spaces.

Tagboard (Vox AC30)

Tagboard Pros:

Less initial preparation or board for assembly than circuit card (eyelet cards) or PTP (similar pros to circuit cards), ease in change of component placement in layout.

Cons More design time involved, longer assembly time than circuit cards. More complicated wiring schemes than Circuit Cards, Harder to Repair, Parasitic capacitance with smaller parts jammed in together.

Turret boards (Early Marshall and Hiwatt)

Pros

Turret Board was the Military standard in WW2. The Turret board incorporates the durability of true PTP, adaptability and ease of assembly circuit cards and Tagboard.

Cons: More involved board preparation than tagboard or eyelet circuit cards. Some more difficult to repair than an eyelet card.

Cons common to all from an economic (mfgs) viewpoint: labor intensive, but that has nothing to do with better or worse.

PCB are used by Fender, Marshall, Peavey, Vox, Mesa, and many other smaller manufacturers

PCB I will assume everyone is acquainted with PCBs. A printed circuit board is a piece of copper-clad phenolic or glass-epoxy board with portions of the copper etched off, leaving copper traces that connect the components together. Some designs are hand stuffed and high volume is machine stuffed.

PCBs were used fairly early by Ampeg in the US, Selmer in England, and Matchless made the switch earlier than Marshall. Soldano (not exactly a low end product) uses PCB

There are good circuit board construction and then there is poorly designed pcbs. PCBs are the current Military Standard, especially for aviation.

Pros: More consistent amp to amp tonal structure. Lower labor fees, so less expensive. Properly designed, a printed circuit board can be every bit as reliable as a good quality as the above alternatives.

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

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.

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.

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

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.

PTP would be the obvious better choice from a repair/modification/reliability standpoint, but a properly designed PCB amplifier will also be just as reliable, but more difficult to work on.

Designing boards to separate power traces from signal traces (not always a consideration in budget driven designs) is not always successful.

PCB often use fast on connections.

Heat issues and heat management an issue not adequately addressed in amps with upside down tubes (Fender Hotrods especially and Fender reissues) Horizontal tubes (Marshall 600 series, Vox AC30CC, some various Peavey).

The previous does not apply boutique brands that use PCB, London Power, Island Amps, Soul Tone (their PCB traces approach NASA standards). Nor does the following apply.

PCBs are part of an ever downward spiral in mass produced major brand name products, and especially guitar amps. PCBs aren't the cause, but part of the equation of think cheap.

PCBs use consumer parts that are chosen as being machine stuffed.

As most PCBs are used to reduce size, small sized electronic components, even though rated the same, are used. These aren't a problem in transistor power supply products, but a larger component size better withstands and radiates of heat in a tube amp design. These parts will fail in this situation and would perform similarly in PTP amps (Cue music, "And my dreams go up in smoke."

PCB input jacks, PCB pots, etc are used instead of more durable chassis mounted versions and in a dollar driven designs, usually plastic and/or cheap quality.

Repairs require extra attention.

And now for a bit of heresy, I have yet to hear a Fender Reissue PCB amp model that wasn't blown away tonally by the original circuit built by a hobbyist constructor.

PCB amps although possible for the hobbyist builder (Dynaco Hi Fis were on PCB) are not generally practical. PTP, etc., would be the obvious better choice from a repair/modification/reliability/updating the circuit standpoint.

A properly designed PCB amplifier will also be just as reliable as the above older alternatives, but more difficult to work on.

Best regards,

Steve

[Gaz]

Great post.

[martin manning]

PCBs are the current Military Standard, especially for aviation.

There is no other way with modern equipment.

And now for a bit of heresy, I have yet to hear a Fender Reissue PCB amp model that wasn't blown away tonally by the original circuit built by a hobbyist constructor.

Heresy? You're preaching to the choir here, man!