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Point to point wiring


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I was inspired by Frank Cooter's PTP wiring amps he took to the LA meet.

So inspired in fact, that I was thinking on building Kevin's KGTT. Besides him and Kerry (and probably Birgir), is there anybody out there who has built it and could post pics of their builds?

My first clumsy attempt at a layout looks bad and it won't improve until I get all the components and have an idea of their size and shape. Hopefully it was done right  :-

A wood case, which I have never done, also sounds interesting.

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KGTT Layout a.pdf

Edited by eggil
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There are photos of Kerry's build around. Maybe on head-fi. His layout is really nice. 

 

It is a shame that so few people are willing to venture out and P2P an amp, and awesome that you want to. The ease of modification & experimentation with a P2P amp is really liberating. Not to mention the simple ability to build things that there just aren't PCBs for. 

 

On that note, why not build a STAX ESX (Singlepower ES-1) with some tweaks to improve performance? I think the base circuit is a bit nicer. 

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The ES1 looks more difficult though. May be not the best for a first P2P build.

BTW, there is not much in google about point to point wiring.

Anything out there worth reading?

Edited by eggil
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Here are some pictures of the amplifier for my Stax SR-407. It is a hybrid construction, the power supply and the phase splitter/differential amplifier are PCB mounted and the output stage is point to point connected.

 

Interior-1.gif

 

 

Salida.gif

 

The pictures correspond to the initial mounting but the current assembly has no changed, simply there are less holes.

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The GES is a lovely amp but I would second Ari's recommendation for the ESX.  Simply a better circuit and easier to build.  Here is my old one:

 

http://i.imgur.com/qzdT4ws.jpg

 

Forgot how colorful it was.  Here is my balanced GES:

 

http://i.imgur.com/8ZDDx.jpg

http://i.imgur.com/4n24s.jpg

 

It's very cramped as the box is tiny and I wouldn't recommend doing that.  Going ever smaller leads to more and more complicated solutions. 

 

Then there is the option of combining the two circuits...

 

http://i.imgur.com/oGWCd02.jpg

 

ESX front end with GES style output stage. 

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I downloaded these from Spritzer's Single Power ES-1/2 repair and restoration thread at the other site.

Spritzer, do you have any PSU boards laying around somewhere you wouldn't mind getting rid of? :)

Also,which triode and pentode tubes does the ES1 use?

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post-2299-0-72514800-1374859699_thumb.jp

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The only PSU boards I have are my shrunk version of the BATE PSU, a simplified version of the T2 supply.  Might need to tinker with it a bit to get it work at these current levels though. 

 

They should use 6SL7 and EL34. 

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post-2232-0-21787500-1374878741_thumb.jp

 

Here's a view of the underside of the amp I brought to the LA meet. It's a simple 2 stage direct-coupled design with Electra-Print 7k:32 output transformers. First stage is a CCS loaded 6SN7 with LED bias. Second stage is a 6AH4 power triode. It was designed to produce about 12dB of gain and a 1.5W output. Power supply is solid -state rectified followed by dual-mono tube regulators. Filament supplies are DIY Hifisupply originally intended for DHT's.  This allows for easy future conversion to DHT outputs if desired. Nothing fancy here. This was built for a friend and the emphasis was on safety, stability, and dependability. I'm honored that it would inspire Enrique to pursue a similar construction technique.

 

When I get a little more time, I'll add some suggestions for construction practices.

 

I have acouple of extra power supply boards for the KGSS if your  interested. Probably could scrounge up a chassis as well.

 

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I applaud the decision to go point to point.  I stayed away from it for years (out of fear) only to realize near the end of my active phase of DIY'ing that it is a ton of fun and while very challenging (you own the whole thing, soup to nuts) it actually helped teach me a bit more about what it was that I was doing with each part.  The first time that really waded into that end of the pool I did full sized layout drawings of the chassis so that I could position bits/pieces and literally see how they were going to fit before drilling a single hole.  I'd highly recommend it.  Also, I'd take a page from Pete Millett and consider using copper clad PCB material as a ground plane or use a large grounding rod like Kerry did for his KGTT (iirc).  Otherwise the only piece of relevant advice that I have is to invest is some good mounting hardware.  Whether that's turrets (like Pete) or terminal strips (like Frank) using crap will cause serious aggravation.  I liked to mix and match, using individual turrets in some places and strips in others.  I actually found a company that makes turret strips, some of which even have premade mounts for tube sockets.  I think Parts Connexion sells them, or did way back when.

 

Here's an example

119231104.ayrgSSJ3.jpg

 

And Frank's work is like the Sistine Chapel of point to point - truly a work of art. 

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They are made by IAG, the Quad parent company.  Well they market them at least... 

 

That is a stunning build Frank but the 'stat amp you had next to it had some ghetto charm.  :D 

 

KGSSHV boards will work but you need to relax the current limiter a bit.  Andy used one in his ES-2 and ran into trouble due to the higher current. 

 

I used to enjoy P2P but today it's just so much easier to sit down, design a circuit board and have a few of them made.  The sub miniature amp took about two hours in total to layout and double check.  That's including checking Mouser for the correct part sizes etc.  I really should just redo that board with the larger 9 pin sockets and bigger caps/resistors for a simple GES PCB... 

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frank wins.

 

frank usually wins.

 

Yes.  Wonderful P2P build, Frank.

 

BTW, I live in Noleta now.  Would you like to get together in the near future to hear the ECP DSHA-1 with HD800 and any phones you'd like?  Either your place or mine would work for me.

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Here's a mock-up example of how I start my p to p builds. 

 

I start with a raw .090 aluminum top plate. First lay out all the major components, If you're using transformers, place the power and output transformers in diagonal corners to maximize the difference between them. Try to keep all power components in a tight area around the power transformer. Signal wires shoud be tight, short, and as far removed from power components as possible. If you have to cross power and signal wiring, do so at a 90 degree angle. Use DC for all filaments. Good AC filament wiring is an art in and of itself. Be prepared to take several different attempts at your wiring. Do not leave connections unsupported or hanging in the air.  Don't be afraid to rip things out and start over. As you progress, you will always see things that you could do better a second time around. Remember always to think about safety and heat dissapation.

 

Everybody that builds like this has a slightly different style.  Rather than planning in advance where each particular small component or connection will be, I like to build a square of tie points around each tube socket and have a sort of connection point grid to work from. I like to keep everything at 90 degree angles if possible. For tie points, I like to use Soviet era Russian military connectors. Seller Sovcom on Ebay is a good source.  I use a combination of 6 and 10 position connectors. They are pretty cheap, yet very high quality. Order 3 times as many as you think you'll need.

 

I like octal tubes rather than 9 pin miniatures. The sockets are much easier to work with.  They also usually sound better.

Many miniatures have octal equivalents that can be used without any circuit modification. A 12AX7 is a 6SL7, a 12AU7 is a 6SN7., etc.. There is no direct octal equivalent to a 6S4, but half a 6BL7 comes close. Better than either of these would be to use a real power tube as an output device. A triode-connected EL34, or a trioide-connected 7591, which would be my personal choice (hey, it was good enough for McIntosh).

 

There's lots more, and I'm sure others have points and considerations I haven't even thought of. Eventually you need to go ahead and jump in. Post your progress or problems here. Don't be embarressed if it's not a work of art at first pass. We're here to help and keep you safe.

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Great post Frank.  AC filaments are indeed black magic at the best of times and it can take a while to master it.  Normally input tubes are more susceptible to hum as they are high gain so using DC for those and AC for the output is also a good idea.  When driving heaters with DC it's also wise not to get hung up on trying to drive them at 6.3V or 12.6V as running them in series saves current which is heat, often quite a bit of heat. 

 

You should also not be afraid of building sub assemblies for the complicated bits which can be added to the circuit.  On the WES style amp I did that to save space and fit pretty much the entire front end on one 8 pin socket adapter PCB. 

 

Agree fully about the 9 pin sockets and they are a pain to work with.  One of the main reasons why it took me over two months to assemble that GES I linked to.  Tiny box with not a lot of options meant a lot of frustration over how things would fit. 

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