Has anyone built a true "point-to-point" layout? (i.e. no boards)

[markmalin]

when I used to restore old radios (30's and 40's) there were no boards, the components were soldered directly to the tube socket.  I've repaired a couple old inexpensive amps like Airline's that do the same.  I got thinking about some of Gerald Weber's lead dress topics, moving tone caps directly to the pots, for example, to minimize lead length.  Just curious if anyone's ever laid out an amp using this methodology?  If so, I'd be curious to see what it looks like.  Seems you could save a lot of space.


Mark

[John]

I tried it twice. Didn't start with a layout like I usually do with a turret board, so it wasn't too neat. You (I) still end up with wires going somewhere. The big drawback IMO is it's way tougher to swap out any component. I do try to mount components on the pots though, and sometimes I'll take a resistor straight from socket pin to turret tie point the board.

[shooter]

I did about the same # as John, came to about the same conclusions.  I'm doing a breadboard PA now, and will probably port it to a box, pseudo-point to point since the screw-terminal layout works, I'll just use that layout with solder lugs

[Ed_Chambley]

I still repair and collect old radios and know exactly what you are speaking of.  True point to point is not even using tagstrips, but using unused tube pins as tie points.  The only time I use a circuit board is when I want to a clone replica or if I plan to do modding I prefer eyelets on a board.


Some of the guys build on tagstrips.  Search the forum for such and you will see Darryl build a nice tagstrip and Dummyload as well.  Sluckey has one he made and it is on his site, or was.


There are arguments between people over this issue, but if you really want a Fender Blackface Deluxe for instance, it would be on a board.  Also, boards and tagstrips make for easier repairs because if you did repair old radios you know how difficult some components are to get to.


Like a Champ or similar.  I would not bother with a board unless I am really wanting to make a proper clone.  Even then I still use G10 or Epoxy with turrents in some places to get resistors up so they cool better.

[sluckey]

I built a couple copycat Sunns back in the late '60s. They were true point-to-point. All my recent scratch builds have been with a board. Boards are much easier to work with, especially when replacing components or making modifications. True point-to-point is difficult to work on. You run the risk of breaking a tube socket pin every time you replace a component. Reliable connections require the component leads to be wrapped around a tube pin or terminal strip lug. You can't just poke the leads through a terminal lug and then fill it up with solder. Many times you may have to unsolder several component leads just to get to the one you need to replace. You must work carefully and slowly. Very time consuming if done right. That's why so many jake-leg tv shop techs just clip a bad component , leaving enough lead to attach the new component with. That really looks bad and shows a lack of pride in workmanship.

I own several point-to-point amps that I have restored or done major conversions on. I didn't design the overall layout, I just adapted my circuit to work with the existing general layout. My latest project, a Hammond AO-63 conversion, is the most complex conversion I've done. There are major changes in that chassis! Took a long time to clean off the tube sockets and then lay the new circuits in. Take a look...

     http://sluckeyamps.com/hammond_2/hammond2.htm

And here are my other point-to-point conversions or restorations. The Magnatone was just a restoration except that the power supply chassis was stripped and redesigned to incorporate two dual cap cans rather than a single quad can.

     http://sluckeyamps.com/magnatone/magnatone.htm

     http://sluckeyamps.com/rocky/rocky.htm

     http://sluckeyamps.com/PeeWee/peewee.htm

     http://sluckeyamps.com/hammond/hammond.htm

All this stuff has a rat's nest look. But if you look closer and compare the schematic, there is quite a bit of logic behind the layout. One thing you may notice is there are plenty of ground points on the chassis.

I've seen some recent very beautiful true point-to-point amps over on the amp garage forum. Not at all the typical rat's nest that was common back in the '50s and '60s. Take a look over there too.

[12AX7]

I have an amp that was a very simple circuit and i rebuilt to a different circuit and therefore the board had no room for a lot of components and i do a lot of it right on the tube sockets. It's a very good sounding amp and very quiet too. One way to do it is use small strip with 2 or 3 terminals on each side of the tube bolted down to the screws that hold the tube socket. Then you have the center terminal as a ground and a few terminals for non grounded components on both sides of the tubes. I bet it would be a vert good way to build due to a lot less wires/length.  If i were to build another amp with a very simple circuit i would no doubt use that method. Otherwise it's just easier to use a board, especially if it's a circuit you know you're likely to tweak and experiment with.

One thing i never thought of before i did that tho is that there are components i will no longer put on the board even when building a amp with a board. Those are components that have no need to be on the board and they only add more unnecassary wires. for example, in my amp the first stage coupling cap goes to the gain pot. So it goes on the board. But the second coupling cap goes from the plate to the next stage's grid, so if you put that on the board you have a wire to the board that connects the cap, then another going back to where it came from in the first place. So it's ridiculous to put it on the board. You can solder it directly from the plate pin to the grid pin of the next stage or if theres a grid stopper solder those together and either let them fly with leads as short as possible or use a terminal standoff like i mentioned above. I'm not a tech and i haven't built many amps so this simple logic only now occurred to me. But thats the way i would do it if i built another amp....anything that needs to go to the board will, but if not i'd solder them directly to the socket. makes a lot more sense to me and should lessen any chance of oscillation too. 

[markmalin]

Thanks guys.  Sluckey, that's some pretty cool stuff on your website!  and Ed_Chambley, I guess I had forgotten about all the issues both of you guys mentioned, the way the old radio's had leads wrapped multiple times around the socket pins, the way old radio repair guys clip a lead and solder to it.  Even the way the guy who trained me would test a cap by clipping one lead, attaching it to a tester, then pushing the lead back together and soldering it back on!  (actually, I had forgotten things like the old Phillco "black box" things with a cap and resistor inside and wax potting).

It's an interesting thing, though.  Man, Sluckey, you really did some nice work.  It makes me want to experiment, but maybe a circuit that's sorted out so I don't have to replace/swap out any components to get it right after it's built.

To be honest, one thing that brought this up is wanting to build a 1-watt Marshall circuit, or maybe convert my Feral Cat to a 1-watt version...and saving space, maybe attaching some components to the tube socket leads...

[shooter]

maybe a circuit that's sorted out so I don't have to replace/swap out any components

Sounds like a bread-board is in your future
It really is great not having to do-undo soldered stuff.  I had enough "junk" around that my 2 tube'r cost $2.73 for longer stand-offs!

[kagliostro]

...and saving space, maybe attaching some components to the tube socket leads...

I consider, from this point of view, is interesting this board topology



it is Doug's Stereo Guitar Preamp

Franco

[markmalin]

maybe a circuit that's sorted out so I don't have to replace/swap out any components

Sounds like a bread-board is in your future
It really is great not having to do-undo soldered stuff.  I had enough "junk" around that my 2 tube'r cost $2.73 for longer stand-offs!

    I keep building stuff out of spare parts - I think when I do this 1-watter it will help use up my inventory.  Most of my spare parts are new (bad habit of ordering extras).

[markmalin]

...and saving space, maybe attaching some components to the tube socket leads...

I consider, from this point of view, is interesting this board topology



it is Doug's Stereo Guitar Preamp

Franco

Nice!!

[Colas LeGrippa]

All of my amps are true point to point. Once in a while, I'll use a termnal strip close to a tube to experiment, thus avoiding to damage the tube socket. All of my amps are dead quiet beacause I solder the couping caps right onto the pots and use shielded wire from the pot to the next stage. ( no, not the stage where I play )


The look is not terrible though but with time I've learned to do something better looking. I don't have any picture, I've sold them all ( cheap, but sold ).


Colas LeGrippa

[PRR]

Somewhere is a picture of one of Fender's first amps, 1947?, all P2P like a radio.

Radio circuits are simpler, and you have IF coil lugs to wire off.

I think after that early amp came back for repairs, and was a royal pain to re-work inside, Leo (or White) started thinking about formica and shoe-eyelets and developed the boards we know from the 50s through much of the 60s. Certainly many repairs (crap resistors, e-caps) are quick-n-easy this way.

[jim]

Here is my attempt.  London Power pre-amp and powe-amp.   It is still my practice amp but a bit noisy at high volume.....Perhaps a little too small a package.   .Jim

[shooter]

Here's one I called the 369'r 16SN7 and 3 parallel SE 6au6's, the sockets were recovered from a '39 zenith.  The PT section sets on the removed "bottom"

[jjasilli]

To be honest, one thing that brought this up is wanting to build a 1-watt Marshall circuit, or maybe convert my Feral Cat to a 1-watt version...and saving space, maybe attaching some components to the tube socket leads...


That's fine for a small amp.  I rebuilt some Stromberg Carlson APH-1100 PA amps.  Layout is complex, confusing and far from obvious.  No boards; some tag strips; lots of point-to-point.  In one amp many of the resistors were fried, with bodies broken & detached from their leads; so it was not clear what went where. Would have been hell to rebuild without other amps in better condition to serve as models for layout.

[silverfox]

sluckey: Reliable connections require the component leads to be wrapped around a tube pin or terminal strip lug.

I'm not trying to disrespect anyone here but for those of us that had careers spanning the 60's and 70's and into the early 80's, we've seen some really paradoxical builds when it comes to theory vs. practical  application... And remarkably so, it worked rather well contrary to all engineering expectations. On the flip side, if it didn't, not even a physicist could offer a reasonable explanation as to why; Show of hands: Who here has ever heard the term, "Mechanical Replacement" in response to the service departments inability to diagnose and repair a faulty subsystem. Although the sales department would be compelled to defend the installation to the bitter end even though the de$ign simply could not work.. Sluckey, have you ever opened an installation equipment cabinet and thought to yourself, how can this possibly work? And yet it did for the most part. I'm just guessing, having worked as a Field Engineer for Sperry Univac during the 80's and seen what can only be described as, "Marvels of Engineering" or "Inexplicable Phenomena".

I remember my first exposure to TV repair, about 1964. The repairman had lots of TV-radio chassis strewn about the living-room repair-shop and for the first time seeing point to point chassis wiring. Since then I've seen hundreds more similar consumer electronics builds ranging from audio to computer equipment and HAM radios in the 30-160 Mhz range. And while it may have exhibited some sideband hash or distortion to some degree, it worked rather well and reliably for many years. For all practical purposes the product exceeded the anticipated lifespan by decades. I can still find a Magnavox stereo on craigslist in working condition when turned on. Yes, you should replace the capacitors to be certain it won't short but other than that it still functions remarkably well as designed and assembled point to point. In all of my experiences I don't recall having seen a patched in component for the purpose of repair, although it must have occurred or there wouldn't have been all the repair shops out there in the past. "You Too Can Learn To Repair Radio And TV Electronics".

From what I gather, what makes point to point feasible is an underlying knowledge of how signals will interact with nearby components and armed with this knowledge, the builder, when routing the connections, does so in an electrically compatible manner. It is an Art-form. If your interested in pursuing it, make it a beautiful thing and take into consideration the near field interactions between sensitive components. This is what the "Old Masters" understood.

silverfox.

[kagliostro]

I don't consider a real PTP the system adopted by our friend Darryl

but he is a master for sure on this technique




Franco

[sluckey]

In all of my experiences I don't recall having seen a patched in component for the purpose of repair

I worked in a small radio/tv repair shop several years as a teenager and I can assure you this was a very common practice. The more complex the circuit, the more likely you would see it. Everybody did it. I was taught to do it. The bottom line was always money. You would lose your ass if you spent the time to do it correctly. Just snip the resistor/cap close to the body leaving the leads connected. Then solder the new component to the old lead stubs. Some people would make a good mechanical connection, but many would just "lap" solder the leads together! It was so much easier to do this that many lazy techs would do so even when it would have been very easy to make a proper neat repair.

Here is a modern guy showing you how to do it...

https://www.youtube.com/watch?v=PWlbRw4HHuk

[sluckey]

K, I consider that nice example to be true point to point. There will always be situations where a terminal strip or chassis mounted turret is needed to support component leads that don't otherwise connect directly to a substantial anchor point such as a tube socket or pot. An example is the 4 resistors for the grids and cathodes of an LTP PI.

[kagliostro]

Ciao Steve

I can agree with you

but from a purist point of view I was considering real PTP only this kind of construction (this is an old military apparatus)



Franco

[sluckey]

Absolutely. The military or NASA will not use cheap terminal strips as found in consumer electronics. If you look closely at that chassis you will see several chassis mounted turrets. Those turrets are too expensive to be used in cheap electronics. I do like to use them sparingly in my stuff.

[kagliostro]

No,  those are not turrets

those are special capacitors with metal case locked to the chassis with a nut 





and ... not easy to have on the consumer market 

I recovered or bught some of those single turrets that you say, they are very sturdy and nice to look at

like this on Pete Millet 813 SE amp











Franco

[sluckey]

No,  those are not turrets

those are special capacitors with metal case locked to the chassis with a nut 

I can easily see 4 turrets. Maybe more. Look closely...

[kagliostro]

You are right

not in great number but some are there

Franco

[shooter]

having worked as a Field Engineer for Sperry Univac during the 80's and seen what can only be described as, "Marvels of Engineering" or "Inexplicable Phenomena".

My system was the Technicare 1440 HPS, 1st 4th generation CAT scanner, ran circles around everything...BUT  The Engineers were still soldering when marketing and sales started shipping them!!!
3 years later the company and me were sold to GE!

[Raybob]

Point to point, yes.. layout?? Didn't really use a 'layout'.  SE 6V6 made from a lid off of a dumpster VCR and milk crate.

[sluckey]

Now that is truly a unique design! 

[kagliostro]

Absolutely !

Franco

[FranciscoPerez]

Not true PTP, but thought I'd share it anyway 
Stereo SE hifi amp I built some time ago.

[HotBluePlates]

... the components were soldered directly to the tube socket. ... to minimize lead length.  Just curious if anyone's ever laid out an amp using this methodology?  If so, I'd be curious to see what it looks like.  Seems you could save a lot of space. ...

Not "point-to-point" but here's a space-saving amp.  The chassis is 13.5" x 5" x 2".  During the build, I kept hearing the phrase "ship in a bottle" in my mind... Everything had to go in the chassis in a certain order to fit.  Tube socket are below the components strung between turrets.

I've got some minor debugging to do which I've put off for months because I dread disassembling the whole thing to test a method to solve the issue.  And also because I suspect fixing the issue will require a re-design of one of the channels.  Which then goes back to the gripe against point-to-point:  ease of maintenance/modification.

[Colas LeGrippa]

wow very neat

[Ritchie200]

Raybob, that is WAY cool!!!   I am already thinking of cool speaker/crate stacks!

Awesome!
Jim

[jojokeo]

I'm not really a fan of rats nests when looking inside of an amp. I just want to go, "ugh, glad I don't have to work on that brain twister" 

Tag strips are my idea of PTP which looks clean, wires clean, runs clean, maintains clean, and modifies clean. This building style is mostly reserved to more modest builds for me.

[MFowler]

I remember this DaGeezer build from this forum a while back PTP.

[terminalgs]

I think after that early amp came back for repairs, and was a royal pain to re-work inside, Leo (or White) started thinking about formica and shoe-eyelets and developed the boards we know from the 50s through much of the 60s. Certainly many repairs (crap resistors, e-caps) are quick-n-easy this way.

that or faster assembly time for the soldering ladies.

[EL34]

I have built without boards bunches of times
If the donor chassis did not lend itself to having a board mounted in it
Like when the tube sockets are scattered all over the place and not in a straight line

One example is my Stereo Power amp project
http://el34world.com/projects/StereoPowerAmp1.htm

[EL34]

And my Schedule 40
http://el34world.com/projects/Schedule40.htm

[whoops]

What a Nightmare!

I wouldn't want to troubleshoot that

[SoundmasterG]

Here is one that I built. It was a Bogen CHB 100, and I gutted it and used the chassis and transformers. I should have used a better chassis with a better socket arrangement, but I made it work fine. There was a wire up by the tone stack that I had to zip tie in place or the amp would oscillate no matter what else I tried, but it works and sounds great now. It is kind of a pain to work on though! 


Greg

[SoundmasterG]

One more pic. The location of the LED's for the front panel in relation to the power tubes ends up blowing out two particular LED's in the string due to heat. I haven't solved that issue yet, but plan to add a fan in there.


Greg

[TIMBO]

Hi guys, This is true P-2-P OZ style.


It's my take on a "Valve Tree" a method used by amp builders in the 60's by fixing another valve base on top of another to hole the components.

[kagliostro]

Very Nice 


Franco

[silverfox]

Here is one that I built. It was a Bogen CHB 100, and I gutted it and used the chassis and transformers. I should have used a better chassis with a better socket arrangement, but I made it work fine. There was a wire up by the tone stack that I had to zip tie in place or the amp would oscillate no matter what else I tried, but it works and sounds great now. It is kind of a pain to work on though! 


Greg

I believe this discussion about settles it for me regarding the "critical aspects of layout" as applied to audio frequency's. If that amp and the other circuits imaged in this topic are able to function with low noise and no oscillations, my belief in the Mojo of "Layout" is shattered beyond repair... I've suspected this for some time but what can I say. "A picture is worth a thousand words"... Don't get me wrong. I'm all for a nice neat build, as well as not violating an obvious rule-  And that is what I strive for aside from a research project where components are ad-lib until a design is worked out.

silverfox.

[shooter]

the Mojo of "Layout" is shattered beyond repair

Look at the pic in post 38,(which I'm assuming works just fine), built it exactly like the pic, when it squeals n howls like a stuck pig, you might re-think the mojo
I'm with you though, I have built successful amps like post 38, then I mod it and it becomes a useless failure because I let the mojo out
Clean, well laid out designs win for me

[silverfox]

shooter, now you've got me thinking about something of a tangent. I got to wondering what the failure rates were during the production test phase? And worse yet, how many were just stacked on a shelf for later in depth troubleshooting due to the fact, you had an undiagnosable failure mode. I have seen systems that defied systematic troubleshooting methods. I don't know if I've mentioned this one in particular here before but: I was sent on a service call, repeatedly, to find out why a terminal server and associated terminals would hang the communications process. I don't know what happened to that in the end but my final theory was based in the cable run being too long with signal reflections causing the communications errors. That was my first and last lesson in the company philosophy-  We don't do mechanical replacements.

What I'm finding on the point to point is: It seems to take longer to build that way if it's a one off. And there are definitely skills to making it look as nice as the images posted here.

silverfox.

[shooter]

got me thinking about something of a tangent

That's how I always think
I was covering a site 100miles away,  3 other guys gave up, every day they had artifact on the MRI, I packed a bag, spent 3 days, Isolated the problem in time, noon til 2pm, verified system was fine, found the freight elevator used for bringing lunch carts had an arcing contact, notified maintenance n went home!
As to PP failure piles, probably K can come up with a pic next to the tube dump!
My current breadboard project will probably be PP, but not til  the design is verified, modified, and burnt in. 

[SoundmasterG]

Here is one that I built. It was a Bogen CHB 100, and I gutted it and used the chassis and transformers. I should have used a better chassis with a better socket arrangement, but I made it work fine. There was a wire up by the tone stack that I had to zip tie in place or the amp would oscillate no matter what else I tried, but it works and sounds great now. It is kind of a pain to work on though! 


Greg

I believe this discussion about settles it for me regarding the "critical aspects of layout" as applied to audio frequency's. If that amp and the other circuits imaged in this topic are able to function with low noise and no oscillations, my belief in the Mojo of "Layout" is shattered beyond repair... I've suspected this for some time but what can I say. "A picture is worth a thousand words"... Don't get me wrong. I'm all for a nice neat build, as well as not violating an obvious rule-  And that is what I strive for aside from a research project where components are ad-lib until a design is worked out.

silverfox.

Despite how messy the true point to point stuff looks, if you study the connections and look closely, you can usually see that they still follow good layout practices. The one I posted looks messy but when you look closely you can see that grounding is done to a buss with each stage grounded in order, there are grid stop resistors on each stage, grid runs are as short as possible and/or using shielded cables, etc. I also added in some extras like adjustable bias, tip pin jacks, lifted heater center taps, power scaling, and this amp uses a voltage doubler power supply also, which means more caps to clutter things up. I should have used a designed for this project chassis and layout, but I opted to use the Bogen chassis and socket layout, and it isn't ideal. The only issue I had was the oscillation that occurred until I found the optimum spot for a shielded cable up by the tone controls and zip tied it in place. The amp has been perfectly stable and working fine for 5 years now in that configuration. The only current issue is that some of the LED's burn up because they are too close to the power tubes. I'll be adding a small fan to resolve that.


Most of the vintage stuff that had PTP was lower gain also. This amp that I built goes up to around AC/DC levels of gain and does clean ok but the cleans are never as nice as a blackface fender or an AC30 or something. Its about 55 watts RMS too. I would guess that if you tried to get Dual Rectifier levels of gain this type of layout would be very hard to make work ok.

Greg

[Shack]

awesome stuff to look at indeed

[Ed_Chambley]

Hi guys, This is true P-2-P OZ style.


It's my take on a "Valve Tree" a method used by amp builders in the 60's by fixing another valve base on top of another to hole the components.

Yep, when I saw you make this I sort of stole the idea.  I love the boards above the tubes and make them with Epoxy Board and eyelets.  They really come in handy when I am restoring an old radio.  Adding a couple gives me enough tie points where I can clean up the rats nest that all have.