PL Similar to Dynaco - Is The Transformer The Real Basis For WOPL Rebuilds?

[laatsch55]

Bob, I guess I never had a bad system. I went from a Fischer receiver in my teens to a Spec 1, Spec 2 and that lovely Denon table.
Then the K's, .....
Then I built my first WOPL.....oh man.
The Spec system was good. Distortion in the weeds, plenty of power, not much damping factor.....and compared to the WOPL it sounded " sterile"... not much soundstage compared to the WOPL..THE Spec system hasn't been fired up in 5 or 6 years. Used the Spec 1 pre until I got the Acurus, thought that might be my pinnacle, but then got the Rowland Coherence.
And during all this time I was upgrading the K's. First the crossovers. The Speakerlab crosses were junk. Al K's universal's weren't.
Then the Speakerlab drivers came out for the Crites woof, the Martinelli wood mid horn with DCM 50 2" driver and ME 10 tweet.
Then the universal crosses got replaced by Al's EXTREME slope crosses. Every change imade things sounded better, but without the resolution provided by the improved electronics it wouldbe harder to tell.
Right now I'm happy as a pig in shit. I'm going to tri-amp in the near future and I'll probably be done....
Thanks to White Oak Joe we can all afford a state of the art amp with all the power ( CLEAN POWER) we'll need...

 

[Bob Boyer]

...Conclusion : every approach is necessary and the most important thing
is a friendly dialogue...Ciao and let the music play
Marco

That's certainly what I was hoping for here (along with some education) - and got. Thanks to all for some enlightenment. I have things to think about, which is what I was after.

 

[wattsabundant]

This thread started out with a mention of Dynaco transformers which is my direction here.

My first real job in 1978 was at Custom Coil in Zanesville, Ohio. I was more or less an engineering tech. I learned a lot about transformers that I never wanted to know. It was BORING. I did a lot of reverse engineering for several customers who had a critical piece of equipment that had a burned up transformer and no other options for replacement. I've torn down transformers with melted 42 gauge wire (I could see then). I left the company never intending to touch a transformer again. 20 or so years later I connected with John and Joy Peterson who ran Sound Values.

Sound Values bought out all of the Dynaco stock, 7 trailer loads as I recall. I tested hundreds of PC28's, the driver board for 400/410/416 amps. I did warranty repairs and whatever else came up. Sound Values changed their name to Sound Valves when they decided to resurrect the Dyna Stereo 70 tube amp. Incidentally the name Sound Valves was an accident that came into being when customers called in and didn't realize the difference between value and valve.

Dynaco started out by selling transformers, both power and output. I think it was the late 50 or early 60's. At Sound Valves I first reverse engineered the Stereo 70 power transformer which was pretty straight forward. Then came the output transformers. As I recall the centertapped primaries were bifilar wound (two primaries simultaneously) so each one had the same resistance/inductance characteristics. It drove me crazy and it took me a couple attempts to get it right.

Once we got the Stereo 70 into production myself and two other final test techs at our day job tested tube amps a couple nights a week . Of course we went out for happy hour first and then worked on amps with a 400 VDC power supply while slighlty impaired. I still go out for happy hour now and then. I try to avoid impairment. I certainly don't work on tube amps or any other amp in that condition.

 

[Bob Boyer]

This thread started out with a mention of Dynaco transformers which is my direction here.

...Once we got the Stereo 70 into production myself and two other final test techs at our day job tested tube amps a couple nights a week . Of course we went out for happy hour first and then worked on amps with a 400 VDC power supply while slighlty impaired. I still go out for happy hour now and then. I try to avoid impairment. I certainly don't work on tube amps or any other amp in that condition.

OMG. Love it, Don! I had a couple of years in my youth I'm also trying to figure out how I survived. Good to know my friends and fellow DJs and myself weren't the only ones.

 

[nakdoc]

I've often shared my views about vintage equipment and the sounds they make. Taking an old unit and replacing caps always seems to bring joy, but who really knows if the original OEM sound was better? We don't have new old stock stored in a freezer to compare. As an example, I will offer the Sansui 5000X receiver. In stock condition, it will make even the harshest CD player sound smooth. Why would anyone want to recap a piece that is already excellent at age 60+? Phase Linear 400 and 700 amps were made back in the "music power" days, when everyone lied about power amp watt ratings. Using energy stored in the massive transformers, rather than in filter capacitors, turned out to be better, and more dynamic, when playing music, but not so much for the test bench. Both amps were somewhat hamstrung by SOA (safe operating area) limitations imposed by the output transistors, but over the years, with many factory transistor substitutions, the SOA protection could be relaxed a bit. Does a PL909 output transistor sound different than the later substitutes? Does the original bias setting sound different than the post-FCC RMS versions with more heat sink? Does having more current gain using modern transistors sound different? And the big question; does quasi-comp sound better or worse than complementary?
One argument is that we don't need to compare a WOPL to the old stuff. I always thought the PL400 was a very harsh and fatiguing amplifier, and would not hold its original sound as any sort of standard for the new versions. Likewise the PAT 4 is not a good preamp, except when you factor in "value" into ownership. I had a PAT 4 in college until I moved up to the PAT 5 and Dyna 400. Once I joined the stereo industry as a technician, and had access to a variety of stereo stuff, I learned that almost everything sounds different. Our logical brains always try to make up reasons why one amp we like sounds better than another (Yamaha B-2 vs. Mitsubishi DA-A15DC...it must be the V-fets are better!), but the reality is, science cannot tell you as much as your brain can recognize listening to "breakfast in America".
So my bottom line is to appreciate the good sounding vintage stuff for what it is, and appreciate the modern stuff when it too sounds good.