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Spud: what, again!?!

Schematic

I remain very interested in the Tubelab Spud design page and details and found a couple of earlier threads where Tubelab pursued the design around 2008.

This: http://www.diyaudio.com/forums/tubes-valves/125963-spud-anyone-6.html#post1795149

Post shows a PDF schematic of a SpudSE design...kind of a proof of concept -- i.e. the "furball" and a schematic as an image file.

This: http://www.diyaudio.com/forums/tubes-valves/125963-spud-anyone-3.html#post1557132

Post (replying to one from above proposing an alternate design), gives some of the values used in a prototype SpudSE design.

I have pulled as much information as I am capable from the threads and the Tubelab website photos to produce a TinyCAD schematic (.dsn filetype) and an image export of the schematic in EMF (Windows Enhanced Metafile) in a ZIP file. I am hoping in your copious spare time you surely don't have, you might take a scan of the schematic and see if it matches with what you designed originally.

However, some of your experiments replaced the triode section cathode resistor/cap arrangement for cathode bias with an LED to provide bias and that is shown in some photos and other posts in the thread referenced above.

Values that I could not decipher from your schematic that are needed (using the numbering scheme on the attached CAD file are: C10/C20 & R10/R20; C11/C21 (0.22 uF?); C12/C22 & R17/R27 (450/5W/20%); R16/R26; C1 (4 to 47 uF?)

An Antek toroidal power TFMR (250 to 300 VAC centre tapped) with a 6.3VAC filament winding could work and Edcor OPT's with a 5k primary.

The volume POT I have placed is a dual 50k log taper device as in your SSE design.

Note, I have added a small section on the filament winding for a power pilot light using a blue LED.

For a free electronics CAD app, TinyCAD is pretty good.


~Squiffy (aka Brad)
_____________________________________
Things are only impossible until they're not...
 

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Free help...

Is anyone else still interested in this thing?
Yes, I am...
If so I will have to make a spreadsheet...
The TubeLab.com spud pages indicate that the prototype board was stuffed with values from the "furball" experiment. In an earlier post, I threw together a schematic and tried to fill the values in from photos, a previous thread on the spud topic and posted the results in a ZIP file. I recognize that several values/tolerances on my schematic are NOT right and I will be adjusting a reposting shortly.

The 6LR8 tubes and B9A sockets are available from a couple of suppliers West of Toronto at a fair price.

So, the BIG question: At this point, is it possible to supply back a part values/tolerance list from your furball (e.g. just read back the values off the "stuffed board")?

Just the power supply and the values from one of the channels (i.e. left or right) would be wonderful.

While I certainly understand the design was not optimized, the opportunity to build an amp in this format remains of interest to me (and hopefully a few others), even point to point, since the stuffed board "sounded good". Cathode bias on the pentode section could be like other posters' adjustable values to achieve a cooler operating point. I have a little time on my hands, and I'm open to helping out, pro bono, of course.

Be back on Memorial day. Until then I won't have time for electronics stuff, and the soldering iron will likely stay cold and so will the tubes....
Just hoping to nudge you back into Tubelab before the 4th of July firestorm you've mentioned has happened in your neighbourhood.

Squiff (aka Brad)
______________________________________
"Things are only impossible until they're not..."
 
I'm leaving on a 3000 mile road trip Friday or Saturday (as soon as it stops raining long enough for me to finish loading my junk. I don't have time to install your schematic program right now....I know this Vista POS computer will fight me on it.

I printed out a PDF of the Eagle schematic, and I am looking at my board. I can provide values for the reference designators on my schematic. You will have to cross them over to yours.

R1 150 ohm 5 watt probably not critical (borrowed from SSE) or use a choke

R2 150K 2 watt Bleeder resistor, use whatever you got

C1 100 uF 450 Volt again not critical 47 uF will work

C2 150 uF 450 Volt

D5, D6, D7, D8 1N4007 or whatever your silicon de jour is

R11, R15, R21, R25 470K 1/2 watt lower value reduces gain I used 470K because I have a bunch

R12, R16, R22, R26 1K 1/2 watt yes....because I have a bunch

R10, R20, C10, C20 dunno....I took them out and put LED's in. Tried a bunch while measuring distortion. Thye are both different, but both yellow.

R6, R5 22K 2 Watt

R14, R24 150K 2 watt.

R81, R28 100 ohm 1 watt.

R17, R27 680 ohm 5 watt.

C12, C22 Both are suspiciously missing must have stolen them for another project. I would use around 1000 uF at 50 volts or so. Some people like smaller capacitance values.

Good luck, post the results here.
 

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I'm leaving on a 3000 mile road trip Friday or Saturday (as soon as it stops raining long enough for me to finish loading my junk.
I wasn't expecting anything until after Memorial Day. Wow...you're my hero. Have a safe trip (Hamfest in Ohio, right?).
I don't have time to install your schematic program right now....I know this Vista POS computer will fight me on it.
I will try some other apps that are more "Vista Friendly" if that's possible. I normally use Mac/Linux but this TinyCAD looked like it had a shallow learning curve and the library expansion looked pretty easy so...
I can provide values for the reference designators on my schematic. You will have to cross them over to yours.
I will do that and update my schematic and repost the results for all (and you) to use, gratis, of course.
Good luck, post the results here.
They should be waiting here when you get back.

~Squiff
______________________________________
"Things are only impossible until they're not..."
 
(Hamfest in Ohio, right?).

The biggest hamfest in the world is in Dayton Ohio. I usually go to shop for tubes. This time, I'm selling them. We inherited a house in West Virginia where I may live when my job runs out.... I am going there for a while too.

I will try some other apps that are more "Vista Friendly" if that's possible.

It's not....Vista sucks. I built this machine about 3 years ago. It worked reasonably well until Windoze 7 came out. Then it started misbehaving. It went through a freezing sickness right after MS installed some "updates" and the sickness was miraculously cured with the next batch of "updates"....Coincidence??? I don't think so......Intentional??????
Between the Windows boot manager and Norton Anti function, Open Suse 9.3 was broken more than it was working...I gave up on it.

I have assembled all the hardware for my next box from Newegg discount sales but haven't had the time to complete it yet. I am stuck with Windows for compatibility reasons (Cakewalk Sonar and others). I had good luck with Grub, but that was years ago on an XP machine. I'll look for a Linux based boot mamager for Ubuntu that coexists with 7.

There has been little interest in the Spud SE, but if anyone knows where to get cheap (Chinese maybe) PC boards made in small quantities let me know. (a 4X6 inch board for $10). To get reasonable prices on US made boards for the SSE, SPP, and TSE I must buy 100 at a time. They are still between $15 and $20 each with shipping and setup charges.

They should be waiting here when you get back.

I should be well connected for most of the trip. The internet in West Virginia is way faster than here, and I'll have my phone at the hamfest.
 
R10, R20, C10, C20 dunno....I took them out and put LED's in. Tried a bunch while measuring distortion. They are both different, but both yellow.
Is it fair to conclude then that you were trying to get about a 2.0-2.2V potential drop across the yellow diode and were finding variability in the cathode resistor/capacitor combo?

Is it possible that since the triode section of the 6LR8 is "12AT7-ish" that you used the same values as in the SSE (i.e. C10 1500 uF and R10 220 ohms)?
C12, C22 Both are suspiciously missing must have stolen them for another project. I would use around 1000 uF at 50 volts or so. Some people like smaller capacitance values.
OK...what would drive lower values as a choice? Remembering that I am just starting my journey into learning about "The Tubes" and other such mysteries.

Plugging away at the schematics...I am going to dummy one up for the 6LU8 as well for the 12-pin compactron option, since I am learning the library stuff in TinyCAD anyway.

~Squiff
______________________________________
"Things are only impossible until they're not..."
 
Updated Schematics

All,

Attached in line are updated schematics for the Spud Amp. These were prepared NOT as a design, but for others to scrutinize.

WARNING: I am very new to the world of tube stuff, so please do not use these as the basis of a point-to-point build at this point. The results could be dangerous if I've missed something fundamental that a more expert person would catch. I'd be remiss to not point this out, as Tubelab himself quite rightly warns about high voltage in these designs. If the attached files have an error in them, proceed at your own risk.

The files attached are JPEGs. The file ending in r0B is the 9-pin compactron 6LR8 version. The other is a version with the pinouts for the 12-pin compactron 6LU8, which I understand is the 12-pin twin of the 6LR8. I have TinyCAD .dsn files available if needed.

Why both 9-pin and 12-pin versions?

Reason? The 9-pin "Novar" (B9E I think) socket in a PC mount form is very hard to find. There appear to be more reliable 12-pin compactron sockets as NOS out there in tubeland.

Others please chime in...I am glad to work on TinyCAD, since I have some time in hand to bash through this. I am still interested in a spud amp with the only silicon being the P/S rectifier. The design is minimalist in both components and feedback techniques (UL mode only in use), which I prefer as a philosophy.

The push-pull movement, while compelling from a power and distortion perspective, does not interest me. I am looking for SE in a small package to drive efficient loudspeakers in a small room from a couple of nice, clean sources. The SimpleSpud certainly has my hopes it can become a PCB at some point. I will contribute, as I can, to assist.

~Squiff
______________________________________
"Thing are only impossible until they're not..."
 

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Reason? The 9-pin "Novar" (B9E I think) socket in a PC mount form is very hard to find. There appear to be more reliable 12-pin compactron sockets as NOS out there in tubeland.

John at Pacific TV has both chassis and PC mount B9D "Magnoval". I'm assuming this is the correct size (0.687" pin circle dia.), but best to ask.

Pacific T.V. - Vacuum Tube Sockets

jeff
 
John at Pacific TV has both chassis and PC mount B9D "Magnoval".

Magnoval sockets have the correct pin circle diameter, but NOT the correct pin diameter. The correct socket in a Novar. Both have the same .687 pin circle, but the Novar has a .040 pin while the Magnoval has a .050 pin.

I know that Stan at ESRC has the right ones because I got them from him at the Orlando hamfest. I picked up a 6LR8 and tried them before buying.


C2 in both schematics should be 150 uF, rather than 100.

It probably won't matter much, but I bought a hundred 150 uF's so that's what I use for everything.
 
I know that Stan at ESRC has the right ones because I got them from him at the Orlando hamfest. I picked up a 6LR8 and tried them before buying.
It looks like ESRC has chassis mount Novar's only right now. Does he have a secret stash of PC mount ones, merely for interest's sake?

~Squiff
_______________________________________
"Things are only impossible until they're not..."
 
It looks like ESRC has chassis mount Novar's only right now.

They may not be listed in his catalog or on his web site. The last time I got any was February at the hamfest. Stan will be at the Dayton hamfest next weekend, so I will find out there, or I may call him tomorrow, since I got another wild idea while driving today. I am also planning to stop at his shop on my return trip. All the tubes I don't sell at the hamfest will be dropped off at ESRC, sold for store credit. It's like trading a few thousand tubes you don't need for a few you do need.

I spent 14 hours on the road today, and unlike many of the other idiots I see, I don't phone and drive......the blonde brain is too easilly distracted. I should have about 5 hours drive time tomorrow, then I'll call him. I got this idea.....while sitting in rush hour traffic in Atlanta. It requires those same sockets too.
 
They may not be listed in his catalog or on his web site.
Are there any reliable sources of drawings for the Novar or Duodecar that show the dimensions of the PC mount sockets.

I've found conflicting info on the Novar -- 11.96 or 12 mm pin circle diameter, 36 degrees between pins, and either a 20 or 22 mm diameter circle for the PC mount tabs on the socket bottom.

The Duodecar is still a mystery for me so far. The sources of these sockets show pictures, but no dimensions. I guess I'll try the EIA documents from, say, a Wikipedia source on the 12-pin sockets or the 6LU8 datasheet references.
I spent 14 hours on the road today, and unlike many of the other idiots I see, I don't phone and drive....I got this idea.....while sitting in rush hour traffic in Atlanta. It requires those same sockets too.
The phone thing drives me nuts too. Near where I live, a recent news item indicated a distracted driver was so focussed on his cellular call that he didn't notice the local police officer driving beside him, for 6 MILES, stopping sporadically at various traffic lights, with the christmas tree lights blazing. Since driving without a hands-free device is illegal here too, and part of a blitz by regional police, the guy received a multi-tiered fine when the officer finally put him out of his misery, wailed his siren and pulled him over.

On your "idea" front, just leave me two (2) little Novar sockets, OK? ;)

~Squiff
______________________________________
"Things are only impossible until they're not..."
 
Are there any reliable sources of drawings for the Novar or Duodecar that show the dimensions of the PC mount sockets.

I've found conflicting info on the Novar -- 11.96 or 12 mm pin circle diameter, 36 degrees between pins, and either a 20 or 22 mm diameter circle for the PC mount tabs on the socket bottom.

The Duodecar is still a mystery for me so far. The sources of these sockets show pictures, but no dimensions. I guess I'll try the EIA documents from, say, a Wikipedia source on the 12-pin sockets or the 6LU8 datasheet references.

Pete's library file may have all the PCB hole spacings, although I haven't looked at it:

DIY CAD programs

Here's another site with a chart that lists socket dims.:

Readout and Counting Tube Bases & Sockets

jeff
 
Thanks Jeff. The pin circle diams are helpful for confirmation of what I've found so far.

I am keenly interested in the PC mount hole spacing on the bottom of the socket. For example, the B9A socket for the 12AT7 in the SSE has a pin circle diameter of 11.9mm. The drill holes on the SSE board are about 2mm on about a 20mm diameter circle.

I am after that key dimension for the PC mount versions of the B9E Novar and the B12C Duodecar.

Pete Millett's page looks promising, but I don't have software on any of my various Mac, Linux or Windoze computers that will decode his library.

If anyone has a magic decoder ring, respect in advance.

~Squiff
______________________________________
"Things are only impossible until they're not..."
 
There has been little interest in the Spud SE, but if anyone knows where to get cheap (Chinese maybe) PC boards made in small quantities let me know. (a 4X6 inch board for $10).
Here is one in Malaysia that appears to charge US$9 per board with a setup cost at $75. Not sure about tinned through holes like on the SSE or tinning of the pads. That might be their $18 service showing on the same web page.

Question at this point: A couple of previous posts in this thread indicate that the prototype Spud "worked" and sounded acceptable. Based on the back and forth in this thread and the current state of the prototype and values stuffed on the proto-board, is this an amp that you would consider using as a "daily driver", so to speak, or better as something experimental like "your mileage may vary" and the end-user would need to play with it and tweak to get "good" sound? Really just a musing at this point, but I'm interested in thoughts on the SimpleSpud Protoype performance and the general audiences' experience with Spuds more generally (e.g. compromises).

~Squiff
______________________________________
"Things are only impossible until they're not..."
 
There has been little interest in the Spud SE, but if anyone knows where to get cheap (Chinese maybe) PC boards made in small quantities let me know. (a 4X6 inch board for $10). To get reasonable prices on US made boards for the SSE, SPP, and TSE I must buy 100 at a time. They are still between $15 and $20 each with shipping and setup charges.

Safe travels Tubelab. My parents still live in Ft. Lauderdale (and I grew up there back when there was almost no buildup west of Executive Airport), so I am saddened to see it's decline as well. I may be moving to DC in the near future, you're welcome to visit whenever West Virginia becomes too rural.

For small PCB runs I like to use:
Fusion PCB Service [PCB08511P] - $9.90 : Seeed Studio Bazaar, Boost ideas, extend the reach
10 100mm x 150mm PCBs for about $70, 50 for $160. I've used them in the past and have always been impressed with the quality and speed for the price. I'm not associated with them in any way, just a past user. It's almost not worth even etching my own anymore.
 
I am after that key dimension for the PC mount versions of the B9E Novar and the B12C Duodecar.

I have Pete's mechanical drawings of the "Big Red Board". The 12-pin circle diameter on the board measures ~1.0". I'm sure someone else can confirm this, George maybe? I remember the socket solder tabs were fairly flexible, so wouldn't be an issue if you were a bit off. I didn't buy any extras, and the chassis mount sockets are different anyway.

Pete Millett's page looks promising, but I don't have software on any of my various Mac, Linux or Windoze computers that will decode his library.

There is a free version of Eagle which theoretically will let you view the library files.

jeff
 
I have Pete's mechanical drawings of the "Big Red Board". The 12-pin circle diameter on the board measures ~1.0".
"Very extra special good, Mr. Coleman, sir!" (Dimitri...Trading Places - the movie). Great start for layout purposes.
There is a free version of Eagle which theoretically will let you view the library files.
"Hello?!? McFly?!?" -- I do have EaglePCB freeware. I will proceed with that.

Sheesh -- my degree in Mech. Eng. should have made me more resourceful. Luckily, I have you guys to rein me back in and stay on task.

For the various watchers of this thread, query -- is anyone else interested in a Tubelab optimized Spud? Unless I am the only one voting, my meager single vote won't help get this off the launchpad.

~Squiff
______________________________________
"Things are only impossible until they're not..."