To match the J112 I didn't need any special jig, I matched them in circuit. On one PCB I installed socket pins for J112 (pins from IC socket), I insert the J112, measure the voltage accross R27 (220ohms), and select two JFET with the same voltage drop on R27. Most of the JFET I tested from my bag were pretty close to start with. Solder the other JFET on the PCB, left the pins on the first pcb. Easy
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It was the recording. I was running it with the Audio Note AN K/LX. I've also run them with Acoustic Energy AE1 ( aluminum drivers ) and it's an accurate treble. Whereas the P2 is a bit softer. Consequently, the P3 is more accurate and shows blemishes in the recording, whereas the P2 seems to tone it down.
Bottom line is that as built, the P3 has a more extended treble. I have the Burson opamps waiting, but I want to listen more.... this is fun. Now, I need to find my copy of Brothers In Arms.... 24 years ago, after the construction, I put up the LPs back on the shelves but didn't arrange them. I told myself someday I'd do it, but somehow I've always found that it more satisfying to listen than to arrange... except when I want to hear something specific...
I have no issues with hiss in either P2 or P3. Running 55db gain for the Grado 1mV. BTW, my P2 has a lot of good parts with a custom backpanel ( no DIP switching for me)... so maybe it's a Super Randy P2.
The words I use are not squishy at all... they are standard audiophile jargon.
At least, you didn't drag me into an ASR like discussion about "fast" bass.
I mean, what do you want?
I hooked up my HP1980B to the output of the P3 set up with an input of 1Mohm..... Ran an HP3325B in a sweep test at 1mVrms with a SissySIT... from 20Hz to 20Khz. The measurement graphs show a +/- 3 db from 17.07Hz to 21.88Khz. With a 1Khz square wave, the rise time was 40Mhz/sec, the slew rate was..... All components were calibrated, instruments were programmed via an HPIB board. Room temp was 20C, sea level, humidity of 50%.
Julian Hirsch and ASR are simply not my forte when it comes to listening to an audio component ( Mind you, I know how to run lab/metrology instruments quite well). But at this state of my life I trust my ears... so if I tell you the bass is EXPLOSIVE, it just means that the macrodynamics are... AWESOME.
Warming the stereo... NOW...
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Hello tonyEE
To hopefully keep this fun and on topic You could call me dtME.
I am from the school of thought that I can measure things that I can not hear and not so much the other way around. Then there are times when the test bench is at the other address. You know that time and place thing.
If the playback of the drum set solo lacks dynamic range and impact (pun) the first place that I would look is the power supply. Does the voltage regulator maintain the output voltage or does the output voltage sag on the crescendo.
The ne5532 slew rate is more than fast enough to keep up with audio frequencies.
When the curly redheaded girl next door comes over to visit keep the door to the lab closed.
Thanks dtME
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Pretty much, taking the standard measurements, which today entail frequency AND time domain.... is the baseline.
What we lack is an understanding of why things sound good. We know when things sound terrible... and we can usually measure that. like a lot of the early digital stuff was done in the frequency domain... but when they got around to the time domain they started to see stuff like PRE-RINGING.... ooops... not good.
Similarly, if an amplifier can't deliver the "rated power" then it's likely two things (a) the rated power is optimistic for the design or (b) the amp is faulty/broken.. It could be the FE or output stage are not up to par and/or the power supply is not able to handle the necessary power. Either way this can be easily measured with a function generator, a resistive power load and a voltmeter ( a scope would provide more interesting data ).
But, just as Pass has noticed that negative 2nd harmonic sounds good.... we don't know why. All we know is that if we start with an amp with little harmonic distortion and add just a bit of negative 2nd harmonic the soundstage sounds more realistic. Why? We don't have the cognitive models that explain and predict it. We just know that it just is. I believe Pass did write about this very specific issue.
It's kinda of interesting and I don't know that much has been done in the research. Back in '85 I almost went back to get a PhD studying psychoacoustics in the Physics Dept at Cal State Long Beach... they had a prof doing interesting research into it... including electronic design, etc.... but by then I was making money and it was hard to be poor again.
BTW, if my user name reflected my profession, it would be TonyPhy...... but my username is usually TonyE... when I created the account in here, that username was taken... so my second option was TonyEE. A number of people think it means something different. It was an unfortunate decision but I remember that username ( use it in other places with such issues )...
Anyhow, I still have not been able to get around listening today... too much stuff going on, but the stereo is playing the radio nicely...
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There also exists those adapters which makes two single opamps to a dual dip8.
I have some singles so I acquired some of these adapters. Then I found out that 4898-2 has equally good specs as the 4898-1. Then I just go with the dual type. I am not an "opamp rolling" person. I just want the P3 to be quiet with low distortion.
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Yes, I'm rather the same. Once I hit the target, I am less interested in constant change. Unless it's making something new...
I guess the dedicated P3 chassis two box set is not yet available for purchase from ModuShop?
Yes it is nice not having to worry about paying the rent.
I have one of the Pass H2 pre amp kits here on my bench. I think that I will apply some of the power supply technology from this P3 project to hear any effects of 2nd HD 180 degree phase.
Seems like there is always an ample amount 3rd Harmonic that comes along with the 2nd
Thanks DT
I have a belt driven Linn LP12 with Lingo, Karousel, Trampolin, Ittok, Grado Master 2.... no distortion!
Now, you guys with direct drives, specially those Technics... well, that's a different story.
Besides, I warm up my turntable and then before getting serious, for five metric minutes I play some special Linn Keltic tunes while I dance ( it helps I'm on a slab, if you're on a suspended floor you should get the Linn Keelare Dancing Platform). This way you get the table heretogenized with the preamp and tuned correctly.
Yes, that I why I don't care much about the opamp and just select a good one that has low noise.
Pfft... I just bought a brand new MoFi Dire Straits Brothers At Arms... and a brand new pressing of Queen A Night At The Opera... I know I have those LPs but I'm not about to go through 40++ linear feet of LPs to find them... so I bought them at the Audio Salon down the road... Life is too short.
Stereo warming up...
Stereo warming up...
The number of times I've pulled a record out only to find a 2nd or even 3rd copy elsewhere in my collection is too high! But, it is a good opportunity to take the best condition disc, sleeve and cover and combine them! Then pass along the others for a buck at a yard sale.