[Bill Thomas]

     Thank you BOTH for your kind comments.  (BELIEVE me, it helps!)  There are those who make a tidy living parting out these things and selling the remnants on eBay.  (Not *quite* as easy to do today, since *some* "good quality" parts are available again.)  While I don't have an ENDLESS supply of original parts, I DO have the luxury of being able to select from a pretty big "closet" full of original Dynaco gear I acquired over the years.  Since MOST of it was assembled from Dynaco "kits", the quality of the assembly is all OVER the place.  Some of it is not too bad.  Most of it is pretty scary, in one way or another.  I happened to build my first electronic "kit" (an EICO Resistance/Capacitance Bridge) with a 250 Watt Soldering GUN when I was about 9.  The fact that it worked was beside the point!  But I see MANY Dynakits that were assembled in a similar fashion.  Needless to say, I couldn't POSSIBLY just turn that kind of equipment back "into the wild" with a clear conscience.  But the "classic" Dynaco gear DESERVES to live.

     The Dynaco story is a true "American Success Story."  While other companies were doing everything they could to wring extra dollars out of the public, Dynaco was doing everything POSSIBLE to keep the cost to a bare minimum.  Their goal was to place VERY good sounding equipment into as many homes as possible, at the lowest possible price.  (We should be so lucky to have someone like Dynaco around today!)  Did they make compromises?  You BET they did!  If they could use a 2 cent resistor instead of a 4 cent resistor without affecting the sound quality, they did it!  People today wonder why they didn't use higher quality parts.  The reason is simple.  It would have increased the selling price of their products.  But as a result, they managed to sell something like 500,000 Stereo 70 amplifiers!  (Estimates vary about the total number, but everyone agrees that the Stereo 70 is the biggest selling amplifier of all time by a WIDE margin.

     I have always respected the folks at Dynaco for their Corporate Philosophy.  The late Bob Tucker (co-designer of the Stereo 70, and writer of Dynaco's SUPERB construction manuals) summed it up quite well:  "The real art is bringing the greatest good (music) to the greatest number."  Dynaco did that, and they did it well!  People today have little idea just how GOOD this stuff really can sound.  My goal is to honor this wonderful company, and the truly "musical" products they produced.  They left a lasting impression on me from a very early age.  That impression hasn't dimmed very much in all these years.

     I had the honor of talking with a couple of gentlemen who worked at Dynaco "back in the day."  They all just "chuckle" about their gear just SURVIVING for this many years.  NONE of them ever *considered* that we would be using their products 50 years later!  But they are (or were) certainly "tickled" that we do!

     I had a brief conversation with Ed Laurent before he passed away.  To ME, it was like talking with Walt Disney, or Chuck Jones.  Needless to say, I was like a star-struck kid again.  But Ed was EXTREMELY gracious and kind, and managed to put me at ease VERY quickly.  He was tickled that we were still using the products he designed, but he didn't make a big deal out of it.  I will say that he was VERY protective of the Dynaco "name" and the gear they produced.  But he was EXTREMELY humble and NEVER acted as though he were anything "special" in the audio world.  But "special" doesn't BEGIN to tell the tale.  After Dynaco's reign as the "King of Tube Electronics" was over, Ed switched to their speaker department and put his expertise to good use designing speakers that are STILL a "great bang for the buck" today!  But Ed still had one "last hurrah" up his sleeve.  He designed the Mark VI (tube) amplifier!  Ed, wherever you are, you are SINCERELY missed!

     I'm documenting these builds for several reasons.  First, I have a LOT of this stuff in my "overstuffed" closet!  It's not doing ANYONE any good just "sitting!"  I want folks to get a chance to appreciate the AMAZINGLY good sound quality these Dynaco products can offer.  But more importantly, I want to show people that it is not beyond the ability of anyone who can solder properly, to repair, refurbish, or restore their own Dynaco products.  There ARE things to watch out for, and there ARE components that are now made of "unobtanium", but for the MOST part, your old Stereo 70, or PAS-2 or PAS-3 preamp CAN have another lifetime of use.  (Just wait until we restore an FM-3 tuner!  We WILL in the coming months!)

     By the way, some folks have wondered why I have "named" these projects.  Well, since I have been around a bit longer than Dynaco has, it helps me keep track of each project! (lol)  Besides, each project has just a *wee bit* of difference, so naming them helps me to know which one you might be referring to.

     By the way, if you happen to have any questions regarding the repair or restoration of your own Dynaco (tube-type) gear, I will be MORE than happy to discuss it with you.  I'm no guru, but I just *might* be able to help you with some of your questions.  Feel free to e-mail me at nostubesforyourdynaco@gmail.com.  With any luck, we just *might* be able to "keep 'em going" a little while longer.

Sincerely,

Bill Thomas

P.S. I'm in the final testing phases of the PAS-3X preamplifier.  All the line sources have been checked and I'm *just* getting started on testing the Phono Preamp section.  I hope to have a final report VERY soon!

Bill

[joeriz]

Beautiful job, Bill!

Joe

[dorokusai]

I agree, excellent work indeed.

Mark

[SET Man]

Hey!

  Wow!  Superb restoration work you did there.

  Nice to see someone giving a new life to these classic tube audio components.

Take care,
Buddy

[Bill Thomas]

September 22, 2008 - Update:  "Something Old, Something New, Something Borrowed, Something ELSE!"

     Since I have been "married" to our current PAS-3X preamp build for a couple of weeks, the title of this update seemed rather fitting.  All good things must come to an end, however.  The end of our project is FINALLY at hand.  There are a few "finishing touches" to address.  First, our rear panel looks a bit "naked" without the proper label.  As it turns out, part of my delay in finishing the project had to do with locating an existing PAS preamp label that was suitable for "touch-up" and re-printing.  Here's a quick (reduced) picture of that scan.



     Cleanup is not as simple as it sounds.  After performing a high-resolution scan of the rear panel, I spent MANY hours cleaning up the result.  After a particularly grueling session of making the blacks blacker, and the edge transitions cleaner, I took a break and sorted and inventoried more NOS Dynaco parts.  Lo and behold, I stumbled onto a few NOS labels!  Here's a photo of the one we will use:



     This is the later "Dynaco" branded version.  Since this is the version used on the last production run of original PAS-3X preamplifiers, it seems more fitting to use this version on our "Final" PAS-3X preamplifier and it'll save untold hours of cleanup on our prior high-resolution scanned label.  (And some people say there is no God!  I have PROOF otherwise!)  Here's a picture of the Rear Panel of our PAS-3X preamplifier with the NOS label attached:



     OK, that's ONE "finishing touch", but now it's on to something MUCH more important, namely: tubes!  Since this is a very "special" project, we need some really *special* 12AX7's to populate the finished preamplifier.  I think it's safe to say that there is probably no more "special" 12AX7 than those made by Telefunken.  Dynaco thought so too!



     These are original Dynaco-branded, Telefunken-manufactured 12AX7's.  For proof, just look on the bottom of the tube and you'll see the Telefunken "diamond" cast into the glass.  Here's what to look for:



     No, these are not brand new or NOS.  These were "reclaimed" from existing PAS preamplifiers.  Since a "stock" PAS preamplifier runs these tubes at well UNDER their rated filament Voltage, these tubes last nearly as long as rocks.  BUT, (isn't there ALWAYS a "but?") there is a "dirty little secret" concerning Telefunken tubes.  They tend to be *slightly* microphonic.  When you tap on the glass of most Telefunken 12AX7's with a pencil eraser, you'll hear a rather musical "dong" produced.  Usually, it isn't too pronounced, but *occasionally* it can be serious enough that high sound pressure levels can cause mechanical "ringing" in the audio.  These tubes have been carefully selected from my "reclaimed" Telefunken's for lowest microphonics, balanced with strongest performance.  A preamplifier this nice simply deserves the BEST!  I've also added a NOS RCA 12X4 rectifier



     So what's left?  Well, our final items are both cosmetic AND *crucial* to provide the lowest noise, as well as the most reliable operation of our PAS-3X preamplifier, namely: the top cover and the bottom panel.  Here's a picture of our re-plated bottom panel with the rubber feet installed:



     But the top cover is also vitally important.



     Note: this Top Cover is not cosmetically perfect.  You can see a scratch on the right and some flaws in the paint elsewhere.  But after 40+ years, we'll just call this a pretty good "survivor" and the best one I have available.  Dynaco relied upon these metal parts to provide a completely shielded enclosure.  Without them, the overall noise and hum levels increase significantly - an increase of as much as 6 dB!  Even MORE in an "electrically noisy" environment.  (Triac "hash" from lamp dimmers can be especially troublesome.)

     We have one LAST "finishing touch"  and then we can FINALLY call this project a "wrap!"  Take a look at these little beasties:



     These are original Cover Screws for the PAS-3X preamplifier.  (Sorry the picture is less than ideal.  It was shot in the dark with a flash.)  If the screws on your unit are silver, they aren't Dynaco originals.  These are brass and although they were EXTREMELY oxidized to begin with, they actually cleaned up quite nicely, thanks to Wright's Brass Polish and fine steel wool.  (And it only took about 45 minutes to get them looking pretty again!)

     Now, at LONG last, our *final* PAS-3X is complete.  Here is a picture of the front of the finished unit:



     And here is a picture of the back of our finished preamplifier:



     It has been quite a journey to arrive at this point.  I have tried to keep the "flavor" of the original design, while applying a few *slight* changes to either improve performance, or increase the usefulness of the preamplifier with today's typical audio sources.  The preamplifier exhibits improved crosstalk figures between sources, it adheres MUCH more closely with the RIAA equalization curve, and has improved bass response throughout.  Cosmetically, it *just* misses an A+ rating, but I would consider it a solid "Grade A" instead.  Let me know what YOU think.

     I welcome ALL communication regarding these rebuilds.  Questions DO arise, usually beginning with "Why did you..." and I am happy to explain the reasoning behind my decisions.

     There is one other bit of information that is important to the proper operation of the Tone Controls in a PAS-3X preamplifier:  "How do you install the knobs so that the controls are indeed 'out of the circuit' when the pointers are at 12 o'clock?"  Here's the trick:

     For the Treble Controls, turn the shaft of both Treble controls fully counter-clockwise.  Now, install the knobs so they point to the 9 o'clock position.  When you rotate them to 12 o'clock, the Treble controls are electrically disconnected.

     For the Bass Controls, turn the shafts of both Bass controls fully clockwise.  Now, install the knobs so they point to the 3 o'clock position.  When you rotate them to 12 o'clock, the Bass controls are electrically out of the circuit.

     I welcome all comments and correspondence regarding these rebuilds.  You may e-mail me at nostubesforyourdynaco@gmail.com, or post your comments as a reply to any of the construction "chronicles".  I will do my best to respond as quickly as possible.

Sincerely,

Bill Thomas

[Bill Thomas]

September 22, 2008 - "Addendum"

     I tried to include this with the previous "Update" but exceeded the allowable number of characters allotted to posting.

     One VERY useful question came from a gentleman who asked, "What are the Voltage requirements of the capacitors in a PAS preamplifier?"  This question pops up frequently.  Here is a list of "reasonable" Voltage ratings for the capacitors in a PAS-2 or PAS-3 preamplifier.  These are not always the original Voltage ratings of the capacitors "as supplied" by Dynaco.

PAS Preamplifier Capacitor List

PC-5 Equalized Phono Preamp Module

     Quantity         Value

   2      .05 (.047) uF   400 Volts (.047 uF is the current standard value) film capacitor
   4      .1      uF   400 Volts film capacitor
   2      68     pF   500 Volts (precision capacitor) mica or polystyrene
   2      2750  pF   500 Volts (precision capacitor) mica or polystyrene
   2      750    pF   500 Volts (precision capacitor on selector switch) mica or polystyrene

PC-6 Line Stage Module

   2      .02    uF   400 Volts film capacitor
   2      1500  pF   100 Volts or more mica or polystyrene
   2      .004   uF   100 Volts or more film capacitor
   2      33     pF   100 Volts or more mica or polystyrene
   2      .02    uF   400 Volts (PAS-2 only) film capacitor
   2      .22    uF   400 Volts (PAS-3 or PAS-3X Only) film capacitor
   2      .0075 uF   400 Volts or more film capacitor

Main Chassis capacitors

   2      .1      uF   100 Volts or more film capacitor
   2      .002   uF   100 Volts or more film capacitor
   2      .02     uF   100 Volts or more film capacitor
   2      2000   uF    30 Volts or more tubular electrolytic capacitor
   1      .02     uF   600 Volts or more (ceramic disc) preferably a "safety capacitor"
   1      30/20/20/10 uF   450 Volt quad electrolytic capacitor

     These Voltage values allow a safety margin under normal operating conditions.  Most values are *relatively* easy to obtain, but it will be VERY difficult to find .0075 film capacitors. .004 uF film capacitors are difficult, but not impossible to find.

     I hope this helps you in your own PAS preamp restoration.

Sincerely,

Bill Thomas

[markC]

Very excellent work Bill! I commend you on your talent and enthusiasm.
This must truly be a labour of love for you. I'm sure your making about $2.50 an hour judging by your asking prices.

[Bill Thomas]

Hi Marc,

     Well, it IS a labor of love and it's my way of honoring the folks at Dynaco who made it possible for people to enjoy High-Fidelity on a budget.  I'm desperately trying to avoid any part of the "greed factor", but many folks really don't believe that.  Here's the "shocking" truth:

     Back when the PAS-3X was introduced in 1966, the price for the kit version was $69.95.  Adjusting that for inflation, we come up with a price of $460.72, in 2008 Dollars.  The wired version was priced at $109.95, which works out to an inflation adjusted rate of $724.19, in 2008 Dollars.  (These figures were determined using Tomas R. Halfhill's inflation calculator.)  In other words, after adjusting for inflation, I have been *trying* to price these items below the original cost of the units.  So, to all those folks who think I'm trying to "rip off" buyers, all I can say is, "You do the math!"

     Also keep in mind that I *am* trying to reduce the amount of Dynaco gear I have been storing for many years.  It makes absolutely NO sense for this equipment to sit in storage and do NO ONE any good.  My original plans for this equipment were canceled several years ago, so why let it just gather dust?  But I simply CAN'T put sub-standard builds into the hands of new owners.  THAT scenario just isn't within my "work ethic."  Nor, would it honor the original Dynaco team.  Instead, it would leave a VERY bad taste in a new owner's mouth for a LONG time to come.  They would never really understand Dynaco's corporate philosophy of "Bringing the Greatest good, to the greatest number."  And, they would never really understand "What's so special about Dynaco?"

     So, that's my story.  People who "get it" will have the opportunity to enjoy some really good sound at a bargain price.  Can that sound quality be beaten today?  Sure!  But there are DOZENS of amplifiers produced today that cost many THOUSANDS of Dollars, yet still can't hold a candle to the "cheap" Dynaco gear.  I also hope that my rebuild articles will help people who wind up with Dynaco gear of their own, lose that little element of "fear" when it comes to attempting a rebuild for themselves.  If I accomplish only that, it will have been worth it.

     I hope this all makes sense.  It's just my way of "giving back" to the audio community.

Sincerely,

Bill Thomas

(September 24, 2008 Note:  My original reference for the wired selling price of a PAS-3X in 1966 turned out to be incorrect.  Instead of $89.95, the wired price was $109.95.  The figures above have been corrected to reflect this.  Sorry for any confusion.)

Bill

[TONEPUB]

Nice article!  Awesome job...

[cryoparts]

Again, color me impressed!   Great work. 

What's next?

peace,

Lee

[Gvt1911]

Bill , you have aroused my curiosity so may I ask what were your "original plans" for all this Dynaco gear ? 
Thanks and great work ! aa

[Bill Thomas]

     Let's just say that I had plans that will never come to fruition now.  It is a bit of a sore point.  Let's just say that Shakespeare was right, and leave it at that.

Sincerely,

Bill Thomas

[wizhill]

Bill, I just came across the thread while trying to restore my Dynakit set that my dad built in the 60's.  I was hoping to keep it as original as possible and was wondering if you still had any of the original parts?  I realize this thread is 10 years old so I'll keep this post short until I know you're still around.

Thanks!

[Mark Korda]

Hi Wizhill,
  Sorry but Bill Thomas passed away a few years ago. His Dyna rebuild videos I have seen are priceless and should be saved at any cost to the Hifi community. He also answered all questions with a lot of zeal and gave out tons of encouragement. I'm not a moderator but thought you should know....take care Mark Korda

[dB Cooper]

Wizhill, you should check out https://www.updatemydynaco.com/. They have lots of resources for stock restorations of Dynaco equipment, as well as upgrades for many, modern substitutes for parts that are made of unobtainium etc.

Welcome to the forums and good luck with your project.

[frankwissman]

I know Bill is no longer with us, sadly. Does anyone know what shielded cable he used? It looks a lot smaller and easier to handle than Belden 1694. Thanks.

[bubbasweet]

Bill can I ask you a few questions about hum in my PAM? I cannot figure it out. THX