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?

I just found this: http://www.geofex.com/Article_Folder...t/pt-to-pt.htm

[Satamax]

I think real PTP is nice since it might be better at eliminating capacitive coupling.

[bob p]

check out RG's pages on this subject at geofex.

[Rob Mercure]

Well, I'll be the first to admit that military specification ("milspec") equipment is overbuilt - I've got a 10W amplifier that weighs about 40 lbs - 14"X12"X3" - made to, as best I can tell, survive a direct hydrogen bomb hit. But for tube equipment milspec seems to have been the most ruggedly designed (but I give Tektronics credit for the most attractive) and I don't believe I've seen a piece of milspec equipment made after the late 1930s that didn't use turrets. Not that I don't mix up my designs - I like cathode current sense, grid stopper, and screen resistors right at the tube socket. Otherwise it does make for a clean easy to service layout.

Rob

[Satamax]

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?

I just found this: http://www.geofex.com/Article_Folder...t/pt-to-pt.htm

check out RG's pages on this subject at geofex.

ZSeems that he already did!

[bob p]

Well, I'll be the first to admit that military specification ("milspec") equipment is overbuilt - I've got a 10W amplifier that weighs about 40 lbs - 14"X12"X3" - made to, as best I can tell, survive a direct hydrogen bomb hit.

Rob, I think you're right. I have lunch on Tuesdays with an elderly friend of mine, and we like to talk shop about tube stuff. As it turns out, he's a retired design engineer from Motorola R&D, and he's the fellow who has taught me the mil-spec construction techniques that I like to use. He was one of the guys that actually built the test gear that went into the atomic bomb test sites, like Eniwietok. The stuff that he built at Motorola was indeed spec'd to survive atomic blasts. Of course, the stuff that got hit at ground zero would be vaporized, but the gear that was not located at ground zero was indeed designed to survive the shock wave and to remain functional after the main blast.

I can't tell you more because ... I'd have to kill you.

[Rob Mercure]

Ya gotta catch me first - nyaaaaaa!

Yeah, this particular amp had a PT and OT each as big as a 50W Marshall tranny and all the filter caps are 4 uf, 600V Pyranoil filled (I used the leaky ones to fry potatoes in <grin>) so no electrolytics. And then all the internal parts were sprayed with a shellac or lacquer that probably has some nasty chlorinated hydrocarbon or heavy metal anti-fungicides in it (check out the material for tropical use equipment in RDH4 sometime). Then it took two 6SL7s, in addition to the 5Y3 and 6V6s, to make a 10 W rated amplifier.

Now the kicker - it was mated to a quite well made, radio station type, turntable. Like phonograph records would survive the shock, overpressure, and heat? Sorta convoluted logic IMHO but I picked up a couple of these for $5 a piece so I can't complain.

Or how about a "weighted" scale dB meter 24X10X18" with nine tubes - not including the five spares under the top cover - but we won't go into that <grin>.

Rob

[tbryanh]

From what I have heard, turrets-board construction is repeatable.

If you develop a good layout method with turret boards, you can repeat that method in each project.

This means your projects tend to be very sucessful.

As far as stray capacitance with turret boards affecting tone. It is not an issue. You need to be aware of what your doing with the parts, but once you got it down, no problem.

I have heard that point to point does not sound better. It is the boutique amp builders that claim this and use it as a sales pitch.

Truth is point to point is not very repeatable, can be very unpredictable, and can be less reliable because the parts have less support.

Turret boards are mil spec. If you want the best, use turret boards.

[hasserl]

From what I have heard, turrets-board construction is repeatable.

Well, on this point a printed circuit board has far greater repeatability, yet they aren't liked too much around these parts.

If you develop a good layout method with turret boards, you can repeat that method in each project.

The same can be said of PTP, there is no difference in this respect.

I think PTP has some advantages, but it sure doesn't look as nice as turret board construction. Turret boards make it easier to swap components on, but they impose some liimits on modifying circuits. PTP gives you more flexibility to modify a circuit in any way you choose. I see PTP wired amps with 4 to 5 decades of use on them with no apparent reliability issues. But no doubt about it, turret boards win the visceral appeal awards.

[bob p]

i think that turret boards offer significantly improved servicability over true PTP wiring. that's the entire reason that turret boards were devised in the first place -- replacing a component on a PTP amp can be a real headache, especially if its buried at the bottom of a rat's nest. in contrast, with mil-spec turret board wiring, each turret contains a maximum of one wire and one component, so replacing any individual component is easy. it could literally be done by someone in the field.