Any one recognize this WOPL 400
- Thread starter stetter
- Start date
If you don't notice it on a PL700B, you won't notice it on a PL400. Remember the S2 has a volume pot on both the 400 and 700. The turnover is out past 90KHz and is single pole so any phase deltas caused by this will be minor within the audio band. If you can notice it, raise your hand 
And in the audio band, the phase is linear with frequency, thus the name "Phase Linear".
Also remember there is a multi-pole 20KHz brick wall filter in every redbook CD player. Given that this filter is such a low frequency, you can hear artifacts of this in frequencies around 8-10KHz and you will notice it if you play a CD containing multiple string instruments or cymbals in it. Then listen to the SACD version of the same recording where the filter is out at 80KHz. Night and day difference. Compared to what you put up with on redbook CDs, any phase related distortion of this amplifier input filter, is truly in the noise.
And don't get me started on the loudspeaker phase distortion...
And in the audio band, the phase is linear with frequency, thus the name "Phase Linear".Also remember there is a multi-pole 20KHz brick wall filter in every redbook CD player. Given that this filter is such a low frequency, you can hear artifacts of this in frequencies around 8-10KHz and you will notice it if you play a CD containing multiple string instruments or cymbals in it. Then listen to the SACD version of the same recording where the filter is out at 80KHz. Night and day difference. Compared to what you put up with on redbook CDs, any phase related distortion of this amplifier input filter, is truly in the noise.
And don't get me started on the loudspeaker phase distortion...
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If you are testing the phase shift at 1kHz you will not see much. If however you are testing it at the extremes on the low end at say 5Hz on a WOPL'd 700 series II amp or 20Hz on some stock 700 series II you should see something. You should also see something on the high end at 20kHz. Are you also testing phase shift with the volume pots at the 12 o'clock position at 20kHz where the worst case scenario is at? NOTE: With the volume pots at 12 o'clock you will see very little difference at 5Hz, 20Hz or 1kHz than when the volume pots are fully CW. By the way, I am using a Powertek SD1000 Phase Meter ($4,500 and still in production). I also validated this with a Tektronix TDS1000C-EDU oscilloscope. I would also like to know what method you are measuring phase shift. Are you comparing the input signal with the output signal? Enough of all of this theoretical stuff. Go measure.
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In performing some measurements I have found the following: the phase shift on a WOPL rev E board with backplanes in a 700 series II amp is better on the low end at 20Hz than a Phase Linear 700 fully comp PL-36 pc board (with the low THD mod). The WOPL doesn't approach the higher levels of phase shift that the aforementioned 700 has until you go down to 5Hz which is the lower limit of the WOPL's frequency response +0/-1dB as measured at 1 watt. On the other hand the WOPL has a little more phase shift on the top end at 20KHz than the aforementioned Phase Linear 700 (with PL-36 pc board). The WOPL has a frequency response from 5Hz - 41 to 42kHz (+0/-1dB at 1 watt). The aforementioned Phase Linear has a frequency response of 12Hz - 49 to 50kHz (+0/-1dB at 1 watt).
As usual, that was an attack on the WOPL and NOT on the discussion of whether or not the Pot causes a lag in phase. Pay no attention to the man behing the curtain... The knobs on my test station cost more than $4500. It's nuclear powered and is still in production. This is how to figure out how much my test set cost.
Or is this how long it take for a genius to build a wopl??? I can't remember.....
Or is this how long it take for a genius to build a wopl??? I can't remember.....
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Stetter, just remember these amps were built by Jerry's kids in the 70's using a chainsaw and chopsticks and I'm surprised that any of them even worked out of the factory. It just kills some people to see that this pile O' crap was re-engineered and improved upon ten fold. It's a kit amp, it didn't come out of a factory and it's a cool hobby. Some guys are just too THICK to figure out that we are having fun building a kick ass amp that kicks the shit out of MOST amps out there including the original Kludge..... Have fun and don't worry about the Captain Dunsels out there. Build away, and if your amp makes you happy, COOL. Don't let anybody Rain (Man) on your parade.
This is what Jerry's kids built....
Ralph Nader should have stepped in on THIS!!!!
Is this the best our factories could do??????? It's no wonder the Chineeze and Japanese kicked our asses in tech.....
This is what Jerry's kids built....
Ralph Nader should have stepped in on THIS!!!!
Is this the best our factories could do??????? It's no wonder the Chineeze and Japanese kicked our asses in tech.....
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Just got done checking out the inside of the new purchase, the difference on the inside compared to the guts on the original is shocking, getting wound up pretty good looking forward to stripping and WO my old amp. One meter loose in shipping, main caps came loose of the hot glue that was used to holed them down. Very glad I read somewhere here about checking for loose meters on shipping, also checked for any loose wire connections. I will do a test run Sunday after getting back from St. Paul. When I get done with mine I will have to do something about getting rid of the hot glue and get caps secured like WO does now
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Show me your facts and data. As well as your measurement and test methods. This forum should be a forum where we are sharing data and making improvements in a civilized way. I have shared a ton of information as well as documents and history on this forum.
By the way, it should be noted that I have restrained myself from personal attacks on individuals on this forum.
It was my original intent to validate the performance of the White Oak Audio products (or for that matter anyone else's. i.e. Nick S. THD+N, etc) and then pass the ball on. I have made this clear to several individuals on this forum via personal phone calls.
I am retired and trying to move on with my life and get out of the Phase Linear arena. My wife would be much happier too.
Just because a White Oak Audio pc board is "pretty" doesn't mean that it will necessarily perform any better.
I have yet to receive a comprehensive list (like Phase Linear published) of the specs for any Phase Linear White Oak Audio amplifier. I suspect that I will like the White Oak Audio Rev D board better than the Rev E board. I know of at least one other VIP on this forum that thinks I will like the Rev D better than the Rev E board.
By the way, any of the Phase Linear 400, 700 and D-500 amps with volume pots will have worse phase shift (at 20kHz) when they are set to 12 o'clock. I wasn't trying to single out the White Oak amps. Like I said the Phase Linear White Oak 700 series II I tested has less (better) phase shift on the bottom and slightly more phase shift on the top end than a Phase Linear 700 fully comp (w/low THD mod) amp.
Don't count on your Spice models until you validate them
http://www.tayloredge.com/reference/Electronics/TestBench/spice_believe-it-or-not.pdf
SPICE models need correlation to measurements
http://www.edn.com/Pdf/ViewPdf?contentItemId=4430457
SPICE op amp macromodels: “Trust but verify”
https://e2e.ti.com/blogs_/archives/.../25/spice-op-amp-macromodels-trust-but-verify
Power Supply Bypassing – SPICE Simulations vs Reality
https://e2e.ti.com/blogs_/archives/...supply-bypassing-spice-simulations-vs-reality
Ed
By the way, it should be noted that I have restrained myself from personal attacks on individuals on this forum.
It was my original intent to validate the performance of the White Oak Audio products (or for that matter anyone else's. i.e. Nick S. THD+N, etc) and then pass the ball on. I have made this clear to several individuals on this forum via personal phone calls.
I am retired and trying to move on with my life and get out of the Phase Linear arena. My wife would be much happier too.
Just because a White Oak Audio pc board is "pretty" doesn't mean that it will necessarily perform any better.
I have yet to receive a comprehensive list (like Phase Linear published) of the specs for any Phase Linear White Oak Audio amplifier. I suspect that I will like the White Oak Audio Rev D board better than the Rev E board. I know of at least one other VIP on this forum that thinks I will like the Rev D better than the Rev E board.
By the way, any of the Phase Linear 400, 700 and D-500 amps with volume pots will have worse phase shift (at 20kHz) when they are set to 12 o'clock. I wasn't trying to single out the White Oak amps. Like I said the Phase Linear White Oak 700 series II I tested has less (better) phase shift on the bottom and slightly more phase shift on the top end than a Phase Linear 700 fully comp (w/low THD mod) amp.
Don't count on your Spice models until you validate them
http://www.tayloredge.com/reference/Electronics/TestBench/spice_believe-it-or-not.pdf
SPICE models need correlation to measurements
http://www.edn.com/Pdf/ViewPdf?contentItemId=4430457
SPICE op amp macromodels: “Trust but verify”
https://e2e.ti.com/blogs_/archives/.../25/spice-op-amp-macromodels-trust-but-verify
Power Supply Bypassing – SPICE Simulations vs Reality
https://e2e.ti.com/blogs_/archives/...supply-bypassing-spice-simulations-vs-reality
Ed
Thanks for the advice on the DBTester. I have one I use all the time for new guitar amp builds and restoring old guitar amps. I powered up the WOPL400 the first couple times with it. Amp responded well on power up no shorts, good Cap response. going out the door to start my drive to Twin Cities. Sure getting tired of the snow. Will try amp tomorrow with speakers.
