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Simple SE with KT88's

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Here's a dumb question: Why is most of the tall stuff (capacitors, etc.) mounted on the bottom side of the board, as if you were going to do an "under chassis" mount? You've gone and put the Phoenix blocks on top, which is going to make an under-chassis mount difficult if not impossible.
 
If it worth doing, it is worth doing right. The screw terminals look taller than the shoulder of the tube sockets. Wiring up before mounting is going to result in using longer wire runs that may lead to interference etc. Also, I think it is best to mount the large cathode resistors on the back of the board as well. Take the time now to do it right and you will not regret it...
 
One more thing, if you may try out other tubes such as EL34's and 6L6GC, I suggest you to use 2 cathode resistors in series (200R + 560R), both 5W or above. Put the 560R close to the socket. When use KT88's, just solder a wire to short the 200R. When use EL34, remove the wire or add another resistor to parallel the 200R to adjust to anything between 560R and 760R. I think Chris has done something similar to this as well.
 
I use these tools: desoldering bulb and desoldering braid

There are nicer tools out there, but these are cheap and work. Find an old junk circuit board somewhere and practice on a couple parts first. Heat up the solder with your iron and suck up as much as you can with the bulb. You can also use the braid to soak up some of the solder. The two pin blocks should be relatively easy. The three pin will be a little trickier, but not impossible. Try not to overheat the board or the Phoenix block. Oh, you'll also want a small flat screwdriver and a pair of needlenose pliers to gently pry and/or pull the parts off the board once the solder is removed.
 
Buy some desoldering braid. Radio Shack carries it if you're desperate enough.

http://www.radioshack.com/product/index.jsp?productId=2062744&tab=summary

One hint: It comes off the spool very 'compressed' and works better if you loosen it up a little bit. Just grab the braid at two points about a inch apart and bring your fingers together. That will spread the braid a little bit. Another hint is that the braid is usually bone dry and works better with just a hint of paste flux on it.

Put the braid on top of the soldered connection, apply heat with your soldering iron. When the solder melts, it'll get sucked into the braid. The braid has a limited capacity to absorb solder, so it's not uncommon to use a few sections (1/4" apart) to get all the solder off. Be careful not to overheat the board -- and this stuff gets HOT quickly, so don't burn your fingertips by holding it too close to the connection.

Use the RS stuff for now, but add a small roll of better quality (anything but RS) braid to your next electronics parts order.

Rick
 
Some braid has rosin so it wicks a little better than the plain stuff since it has built-in flux. You can also put a little liquid flux on the braid to help speed things up if you have never de-soldered before.

Since nobody has mentioned it yet, you need to be careful that you do not lift any solder pads when you are de-soldering. It's fairly easy to solder the braid to the pad when de-soldering and pulling on it can easily pull the pad off. Trying to wiggle the component off before you have completely de-soldered it is another easy way to lift the pads. Tinning your tip well before touching it to the braid gets the heat transfer going and lets the braid wick the solder. You want to get on the joint and off the joint fairly quickly or you risk overheating the components (same as when soldering the components to the PCB). Keep your tip tinned and wipe it often on the sponge. As mentioned above, move to a fresh section of the braid once the previous section is fully wicked.
 
I personally like these.. Vacuum Solder Sucker
You sort of **** it, then when you're ready to suck the solder away, you just press a button. Tho, while I've linked to one at radioshack, I've had two of those break on me. A really cheap one from an online surplus store has lasted me years and years.

And another thing is that the solder cools off FAST. So, if you're using a bulb or one of these suckers, you need to get it on the hot solder as soon as the iron is off of it. You can't even wait long enough to set the iron down or anything. Just in one motion move the tip of the soldering iron off the pad, and the sucker on the pad w/in a fraction of a second.

I have better luck w/ these than I do the braid. I usually don't even have to do any final cleanup w/ a braid. The vacuum tool gets it all.
 
Ain't this stuff fun !!! Like a previous poster said, if it's not right, tear it out and redo it ...

Anyhow, I just purchased one of these from RatShack last week and am kicking myself for not doing so five years ago!!! I like it better than the braid stuff..

An externally hosted image should be here but it was not working when we last tested it.

Desoldering Tool

Keep up the pictures.. Looking great...

Danny
 
Update as of today.

Got about 50% of the chassis mocked up. It was a huge learning experience and I made a few mistakes. Getting the holes lined up for the tubes to come through chassis was a PITA!! The 12at7 tube hole was the first I one I did. Its a little off centered and a little big. But I think once it has paint on it. You won't really notice it.


I also made the hole a little too big for the IEC socket. Had to weld some of it back and grind it down.

Did the same thing on one of the switches. Welded it up and ground it down and then did it again.:mad: Decided it was time to call it a day. I was at the 5 hour mark when this happened. I might have to limit myself to 4 hours or less when working on the amp. Seems I start to get a little fatigued and start making mistakes after the 4 hour mark.

Oh well. You live and you learn. Luckily I had the ability to fix my mistakes..



And thanks to everybody with all there help. I'll be pickign up some sort of desoldering tool shortly.;)


Cheers


Nick



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The holes are tricky to get them lined up with the sockets on the board. Sometimes it needs more luck than skill. The holes around the octal sockets are somewhat forgiving. The tube will likely cover any small miscalculations. As far as the 12AT7 is concerned, well, a nice big hole improves your chances substantially. I used the same size hole punch for all four socket holes on mine.

 
Simple SE Suggestions FWIW

I just noticed this thread, and thought I'd post some "learnings" about the Simple SE board. I just finished my third one, still have 3 boards in stock. The learning curve is pretty steep (that is, learning is quick); #3 took only about an hour to populate the board.

Generally, I am NOT a big fan of PCBs for tube stuff (too much exposure to decaying Dynacos and later Heathkits, I think), but the Simple SE is so flexible that it's a joy to work (and experiment) with.

Suggestions:

(1) changing bias resistors on a PCB is a pain. Initially I used an off-the-board terminal strip wired to the bias resistor pads. Better solution (that I just implemented on #3 and retrofitted to #2) is to use a SINGLE screw terminal (an all-metal piece with a nubbin on the bottom). It's Mouser 534-8730 MINI BINDING POST at $0.47 each. Likely more expensive than Beluga cavier per pound, but it makes rebiasing REALLY easy.

I haven't done it, but you could of course use these terminals on the driver bias and CCS "bias" resistors; that would allow you to easily rejigger the driver operating point so you could use different driver tubes if you were so inclined.

(2) I used 50V 1500uF feedback caps. Don't do that if you are experimenting with high bias voltage tubes like the 6BQ6GA. The good news is that modern caps fail in a fairly benign fashion; these just spewed a dollop of orange electrolyte out the ruptured (pressure-relief) top. Replaced in a few minutes.

(3) soldering the sockets is easiest if you prop-up the board on the 1/2" standoffs that you're going to use (maybe with a little downward pressure). Everything comes out flat and square.
If you are terrifically fussy (I was on #3, but usually in too big a hurry!) punch your chassis BEFORE soldering the sockets, then center the sockets in the holes by slightly bending the leads. Otherwise at least ONE of the sockets is likely to be off-center a little.

(4) I generally prefer tube rectifiers, and they're great for adjusting the B+ voltage a little; e.g. 5R4 for lowest voltage, 5U4 slightly higher, and 5AR4 highest. FREDs of course for the very highest B+.

I strongly dislike standby switches, so I don't use them; always thought there was too much "slam" on the downstream side of the PS. If you are worried about slower warm-up, suggest a 5AR4/GZ34 or a separate fils transformer. I suspect that the troubles with FREDS are standby switch related; I haven't had any issues, but I always start-up on the 5AR4 and only switch to FREDs to see what they sound like on certain pieces (eg. bassy R&R) My 6AV5 amps uses only the FREDs with no issues (and no standby switch).

(5) Strongly recommend following George's advice about multiple multi-meters (sorry, couldn't resist). The Harbor Freight ones are on sale right now for $2.99 (with the cap-powered backlight!!). I have accumulated about 10 or 12 with different weird probes. For example, two have yellow mini clip leads and I use them exclusively for bias voltage measurements. Where I used to start-up an amp propped-up on it's side, with one VTVM, a probe in one hand and a flashlight in the other and a lighted votive candle for good luck, now I just clip-up the cheap Harbor Freight meters, turn the amp right-side up, and flip the ON switch.

(6) Hammond self-branded iron has gradually but inexorably started to **** me off. I used old H-K iron for #1, but switched to the Allied/Hammond. No buzz, voltages right where they are supposed to be, and much less expensive. If you need a lower B+, use a higher DCR choke and/or a higher voltage drop rectifier tube (e.g. 5R4 family).

(7) Power tubes with different pin-outs that you want to try-out can be accommodated by soldering wire leads from underneath alongside the socket pins; just run the leads to the "auxiliary" socket and use ONE socket or the other. starp the wires togerhe with a cable tie for a neat appearance. The board doesn't know the difference, provided that the board connections and internal connections don't conflict.
Plate top caps (e.g. 6BG6) are REALLY simple; just put a grommeted hole in the chassis and run the top cap wire to the PLATE screw terminal.

(8) Amp #3 has the Edcor 15W 5K:8 ohm OPTs mounted UNDER the chassis, but with room to mount Transcendars or similar OPTs on top later if desired. I have used the Transcendars on three DHT amps (45 and 2A3 stereo amps and cool 71A monoblocks for playing Red Dog momo LPs); they are terrific OPTs for the price. However, if you like the ultralinear sound (I do), the Edcors in Ultralinear with one-cap local feedback are the best bang for the buck I have ever seen.
They are especially nice with 6AV5s, but note those have a different pin-out than the 6L6 family.

(9) I really like the "6L6" sound, but NOT the EL34 sound. I fully understand folks that like it the other way round. I've tried about 10 different power tube types so far in the Simple SE, and my two favorites are USA Tungsol 5881s and USA 6L6GCs. The Russian/Czech 6l6GCs are surprisingly good, and I have a pair of new Russkie Tungsol 5881s on order, but so far USED USA GE 6L6GCs are my favs. Playing WGBH (Boston) jazz streaming feed right now.
My "great room" system is VERY hard to fill with good clear sound; it is very large, with Altec A-7 clones built into one wall, with University 15" HC woofers (tough to drive with <8-10 watts). It's really begging for about 20 watts of PP umph, but I miss the SE clarity. The Simple SE with 5AR4 rectifier, USA 6L6GCs, and Edcors in uL with feedback are the best of 10 or 12 amps I have tried in here; enough power to fill the volume (and drive the woofers), but good clarity and that SE "sparkle". Triode strapping a pentode (ANY pentode, as far as I can tell) just doesn't cut it; a nice EL84 PP is better than any strapped pentode in this room. Heck, I tried triode-strapping a 7355 PP H-K amp in here; that just sounded mushy.

(10) Russian PIO caps (I bought a bunch) in 0.22 uF have been a big pleasant surprise. For about $1 each delivered in large quantities ($2-$3 each in smaller numbers) they are much better than ANY plastic dielectric cap I have tried (e.g. orange drops, other less-orange mylar, French zinc caps, Mallories, etc). Haven't done a direct comparison to Jensens or Auricaps or other boutique caps, but pretty sure the Russkie caps are way past the point of steeply diminishing returns.
 
WOW! Nice post and thank you.


I might go ahead and pick up the volt meters just to be safe. I might need them on another project anyway.

But I was under the assumption the SSE was pretty much plug and play... Or am I wrong? I uderstand that I should at least check a few things. But don't have a clue as to what or how. I figured once I got to that point I would follow the tubelab instructions and ask you guys for help on whatever I couldn't figure out from the tubelab website.


I am hoping after you guys walk me through the chekout procedure I'll know how to do it the next time. And won't have to bother you guys with so many questions anymore...


My Opts ship out Monday and I figure it will take them a week or better to get from California. So I can't do anything until they get here.

When they do. I'll go as far as I can and then start asking questions.:)


Thanks again for the patience and help.;)


Nikolas
 
"Plug & Play??" -OR- Even Morgan Jones Cringes

The Simple SE board is as close as I have seen to "Plug & Play" in Tube Amps.

HOWEVER, as somebody somewhere here on DIYAudio noted, even Morgan Jones (author of "Valve Amplifiers", the tube amp bible) says that he cringes when he powers-on a tube amp for the first time.

The high voltages involved with "valves" mean that any mistake may be serious, for example (a) installing the electrolytics backwards, (b) leaving a shard of wire bridging a crew terminal (see George's site) or (c) using only one bolt to secure each OPT, and having one shift position and ground-out the "plate" terminal [I did that one while hacking with one of the Simple SE boards; fried an old 5U4G].

I suggest the following start-up arrangement:
(1) insert a short section of bare wire in the spare ground terminal next to the high voltage Center Tap wire (usually Red & Yellow). Clip a lead to that for the meter grounds.
(2) one meter on the positive side of each power tube bias resistor (the side next to the electrolytic caps)
(3) one meter on one of the PLATES (I clip mine to the tabs on the Edcor OPTs, but you could use a stub wire in the PLATE terminals

That's three meters @ $3 each, plus at least one clip lead. $10 is cheap for the added safety, and you'll need the meters if you want to fine tune (trust me, you will).

George may want to weigh-in with a better set-up.

Before you turn the amp on, FIRST set the meters to the right scale (for $3 each they aren't auto scaling), SECOND have some idea what they SHOULD read, and THIRD make sure you have a load connected to the ouputs (I always use cheap 8 ohm speakers at first power-up).

Voltage at the plates will first rise ABOVE the eventual reading (probably about 505-510 VDC for a second or two if you are using the Allied power trans) then settle down to operating voltage.

The Bias voltage will rise relatively slowly to the operating point; shouldn't overshoot. You should know approximately what that will be; George's charts will give you a pretty good idea.

Just because I am picayune, I always measure and match the bias resistors so my subsequent calcs can be pretty accurate.

The bias voltage divided by the bias resistor value is the plate current in amps (so 55 milliamps will read 0.055 on your calcualtor)

For triode connection, Plate Dissipation is the voltage ACROSS the tube (measured plate voltage minus cathode bias voltage) TIMES the plate current.

So for example if you have 360 V measured at the plate, and 60 volts bias, you have 305 volts across the tube. If you have 60 milliamps plate current, plate dissipation is 305 x 0.060 = 18.3 Watts. (it happens that the tube these calcs came from is rated for ELEVEN watts dissipation!! yahoo!!)

Real numbers:

On one of my Simple SEs, I use an Allied power trans with a Hammond 5H 65 ohm choke.

With a 5AR4 rectifier tube, GE 6L6GC power tubes, 563 ohm bias resistors, and AC line current at 116.5V, I got:

447V at the plates
36V bias / 563 ohms = 64.1 mA plate current
411V across tube x 64 mA = 26.3 Watts plate dissipation
well within the 30 W dissipation listed for the 6L6GC.

[However, note that since that since I am running an ultralinear connection, the GRIDS are likely RIGHT AT the published limit of 450V.]

Hope this helps.
 
OK

So I went to Harbor freight to today and bought 3 volt meters.

Now I have four including a nice Fluke.

I also bought a desoldering bulb and some desoldering braid.

So I am ready to make the board right and also check the board correctly.


But all I have is the probe type connections for the volt meters. I couldn't find any clip on probes. I'll try and find some on ebay or something.

I still don't quite understand where to probe or the numbers I should be looking for. But I am going to reread and reread your post until I understand where and how to probe the right areas.

I still might need some detailed pictures from somebody so I get it right. But I am not to that point yet. When I get there I will let you guys know and then maybe you can help me further.

I feel like such an idiot right now.:eek: I hope I can get this figured out....


Nick
 
I'm about to lose my freaking mind!!!!:smash:


The desoldering stuff is a major PITA! I about had a breakdown. I managed to get all the phoneix blocks off. But I broke one and and a soldering pad came off of the board.

Plus I can't seem to get the board and the blocks clean enough to reinstall the blocks. The holes were barly big enough before. Some will go some won't..


Can I just solder the wires straight to the board?








Nick
 
I feel your pain. Desoldering is harder than it sounds. Did you practice on a junk board for a while first?

I received a circuit board from a seller which had a lifted pad at one connection point. The board is supposed to have these staked terminals, but while he was installing the stakes one got jammed. He pulled it back out, damaging the board. The trace is completely severed, and has no connection to the stake. I was able to work around the damage by making my connection to the next point up the trace. Maybe these photos will give you some ideas.





And yes, you can absolutely forgo the Phoenix block entirely and just solder the transformer connections directly to the board. Just be prepared to get out your desoldering tools again should the need arise. :bawling:
 
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