Post by Owen Y on Aug 11, 2019 17:40:28 GMT 12
Nelson Pass talks to Steve Guttenberg Audiophiliac about how he started out making amplifiers, his first job at ESS Labs, Oskar Heil, starting Threshold Audio, Pass Labs design & manufacturing philosophy, the First Watt company & why they use Tannoy HPD loudspeakers for audtioning their amplifiers at Pass Labs.
|
Post by colinf on Aug 12, 2019 4:59:05 GMT 12
Good to hear Nelson is still grounded about measurements vs subjectivity, and also that measurements are used more for consistency’s sake. He likes the amp design to be as linear as possible without the use of the NFB ‘credit card’, and uses whatever technology works to achieve that, a philosophy that I subscribe to as well. After all, it’s “entertainment not dialysis”! (Quote by his friend Joe Sammett.) Interesting that he sticks mainly to solid state devices.
AMR-iFi R&D
|
Post by Owen Y on Aug 12, 2019 9:41:17 GMT 12
2 good / pleasing points made by Nelson Pass.
|
Post by michaelw on Aug 12, 2019 11:13:14 GMT 12
good interview.
last pass i heard was an aleph model, like a box of heatsinks.
|
Post by Owen Y on Aug 21, 2019 22:34:06 GMT 12
|
Post by colinf on Aug 24, 2019 18:59:37 GMT 12
I’ve always wondered about negative vs positive second harmonic too. Nelson Pass has been designing negative 2nd into his products, a cool feat. I use triodes for amplification as they have a nice ratio of 2nd to 3rd harmonic distortion, and adding negative feedback skews the harmonic ratios too much for the worse. So the circuit has to have low but good distortion in the first place. Recently I’ve been fiddling with low distortion SS circuits and putting a triode in the system to make it sound more listenable through speakers. I like the fact Nelson can play with the harmonic distortion ratios with SS devices at will, and is very choosy over which particular transistors will work in a given situation. It’s almost as if he has two philosophies; Pass Labs is the formal operation, First Watt the fun one where you go out in the convertible in the sun.
AMR-iFi R&D
|
Member
Post by mijoh on Aug 25, 2019 2:31:57 GMT 12
|
Post by colinf on Aug 25, 2019 5:43:55 GMT 12
Yes I have some here but didn’t like them much. They have very low current capability in the order of tens of micro amps instead of milliamperes like normal triodes like the 6dj8. You can get far lower distortion and noise out of conventional triodes without resorting to jfets for impedance matching. As a hifi device the Korg 6P1 has a bit too much distortion and/or noise, depending on the situation it’s in. A 6dj8 SRPP circuit has more than an order of magnitude lower distortion, also an order of magnitude lower noise and much higher output voltage swing. The Korg seems to be a bit prone to microphonics as well, necessitating attention to how it’s mounted. It might work ok as the input stage of a poweramp where a bit of noise at low voltage swing wouldn’t be so noticeable. But as an instrument device, ie, designed to modify the sound of a synthesizer or electric guitar etc. it would work very well I suspect. In that case the noise wouldn’t matter so much and the tone and overload/overdrive characteristics would be important. But what I like about Nelson’s circuit is that he operates it at the point at which 2nd harmonic nulls out. I made a circuit in the 90s with 12au7s in which you could null out the 2nd harmonic also. But the third harmonic was still quite variable with input signal voltage so nulling out the second didn’t seem to make the circuit sound much better. So I concluded that a low distortion circuit with the right harmonic structure, including low amounts of upper harmonics including the third, sounded better ultimately.
AMR-iFi R&D
|
Post by Citroen on Aug 25, 2019 7:27:23 GMT 12
Nelson Pass’ ‘perfect’ massless, full-range Ion Cloud speaker
Tour of Nelson Pass' listening room (Interview 4 of 6)
|
Post by michaelw on Aug 25, 2019 12:15:54 GMT 12
sony es 400 cd changer and humble technics sl1210m5g - not any early version but one of the last. 
|
Post by deano1974 on Aug 25, 2019 18:43:58 GMT 12
He is probably the coolest designer on the planet Would love to spend a night having a drink with him
Manager & Product specialist at Rapallo AV & HI-FI
|
Post by colinf on Aug 25, 2019 23:33:46 GMT 12
I was half joking when I said a full range plasma speaker and a gas mask would be the best speaker. Turns out Nelson Pass has already done it, and gotten carbon monoxide poisoning from it! 😳😊 Love the 1200-jfet amplifier in the listening room. It would make a seriously low noise MC headamp with all those jfets in parallel. One can only wonder what the input capacitance would be. 😳
AMR-iFi R&D
|
Post by colinf on Aug 25, 2019 23:40:39 GMT 12
Just calculating the input capacitance for 1200 2sk170 jfets. It would be in the order of 36nF, not as crazy as first thought!
AMR-iFi R&D
|
Post by michaelw on Aug 26, 2019 21:10:26 GMT 12
I was half joking when I said a full range plasma speaker and a gas mask would be the best speaker. Turns out Nelson Pass has already done it, and gotten carbon monoxide poisoning from it! 😳😊 Love the 1200-jfet amplifier in the listening room. It would make a seriously low noise MC headamp with all those jfets in parallel. One can only wonder what the input capacitance would be. 😳
was that the cause of his well publicised hospital stay and not ozone produced by the hill plasmatronic speakers ?
according to the hill fanpage, the ozone byproduct was a myth.
|
Post by Citroen on Sept 1, 2019 0:10:32 GMT 12
Part 5 of 6 Nelson Pass and his $327 DIY Class A amp
|
Post by colinf on Sept 1, 2019 5:35:25 GMT 12
I love the phrase on creativity...you don’t push the river, it flows by itself. 😀😀
AMR-iFi R&D
|
Post by Owen Y on Sept 2, 2019 14:31:59 GMT 12
Here's our earlier DIY thread on the AMP CAMP kit by Nelson Pass. I think jon was building it.
|
Post by Owen Y on Sept 7, 2019 15:18:41 GMT 12
Tour of Nelson Pass' listening room (Interview 4 of 6) Wow interesting!... - Humble Technics SL-1210 TT but... DS Audio Optical Cartridge!  - Ribbon tweeters - RAAL, Pioneer - Fostex T90 Alnico compression tweeter (I have a pr of these). - Cube Audio (Poland) fullrange loudspeaker drivers, claimed to be the best 'fullrange' drivers made, the F8 model RRP US$2800/pr. - 'SEAS fullrange drivers' (I use a pr of SEAS FA22RCZ fullrange drivers myself - but likely Mr Pass would have the Alnico versions).
|
Post by andrewp on Sept 7, 2019 21:12:12 GMT 12
A very down to earth gentleman I thought. Clearly didnt need have a pair of massive monos in his room!
|
Post by Citroen on Sept 8, 2019 0:15:39 GMT 12
Part 6 of (now) 7 interviews
One for the DIYers amongst you. Nelson's parts collection. including rare Germanium PNP 2SB206 transistor, 2SK77B static induction transistors...
|
Post by Owen Y on Sept 9, 2019 15:38:54 GMT 12
colinf might be interested in the SONY VFETs. I was interested in his support & attitude to his DIY forum members.
|
Post by colinf on Sept 10, 2019 19:55:13 GMT 12
Love the Vfets, Owen. Also that his former business partner Joe loved germanium power transistors. I’ve been making a germanium transistor headphone amp for a while now that uses nos Russian Ge transistors. Some people love collecting cars, others cameras. Nelson Pass loves transistors! I also have a collection of unusual bits, just not on the same grand scale. I think I’ll just stick to devices you can still get, timeless parts like valves and transistors that can be replaced easily if need be. That’s so the amps can be repaired successfully in the field in 30 years. Can that happen with Nelson’s products? If manufacturers made Sony Vfets again (modern versions) I think lots of designers would jump to using them. The SITs made by Semi South looked promising but aren’t being made anymore. So as parts from history, is it wise to design an amp with them? Is making a limited production amp a good idea?
AMR-iFi R&D
|
Post by Citroen on Sept 16, 2019 0:29:01 GMT 12
Part 7 of 7
"Meet Pass Labs’ Wayne Colburn, he works with Nelson Pass"
|
Post by Owen Y on Sept 17, 2019 18:34:34 GMT 12
So... what is the turntable that Nelson's got sitting on the sidebard? ClearAudio? Maybe not....
|
Post by colinf on Sept 20, 2019 2:38:44 GMT 12
It looks like a Basis 2500 (I think) in clear acrylic with Basis Vector tonearm. I had a Basis with the same suspension pods and tonearm. A J Conti is the designer, a brilliant engineer and great guy. I met him at the CES years ago and kept in contact. Wayne and Nelson look like they make a great team. 😀
AMR-iFi R&D
|
Post by colinf on Sept 25, 2019 4:57:03 GMT 12
Some great videos if you’re into DIY on the Linear Systems website, at the Burning Amp festival in 2018. Including my friend Roger Modjeski asking Nelson Pass about distortion cancellation in jfet circuits. Also Wayne Colburn presenting a cost effective decent line stage. www.linearsystems.com/burningamp.html
AMR-iFi R&D
|
Post by Owen Y on Apr 8, 2020 11:44:16 GMT 12
Enjoy the Music.com asks 10 Questions of Nelson Pass: 1. What is your first memory of falling in love with music? 2. ow did you first get introduced to high-fidelity audio gear? 3. What is your favourite piece of vintage hi-fi, and why? 4. When did you decide to start a high-end audio company? 5. What, and when, was your company’s first product? 6. What challenges did you face during those early years? 7. How have your products evolved over the years? 8. What is your company’s most popular product(s)? 9. What is your next planned product offering and its’ features? 10. What advancements do you speculate high-end audio will offer ten years from now? 
|
Post by Owen Y on Apr 8, 2020 20:32:46 GMT 12
I chatted locally with someone today, who owns a SIT-3 (limited production almost all gone) - I'd like to hear one of those.
|
Post by Owen Y on Apr 9, 2020 11:23:03 GMT 12
In the interview above, Pass gives a interesting precis of his amp design timeline - from Threshold to Pass Labs, changing from bipolars to FETs, their patented X-series technology, the First Watt project, the 'current source' F-series & the story of the SIT-series.
|
Post by Owen Y on Jun 2, 2020 11:25:02 GMT 12
Steve Guttenberg AUDIOPHILIAC zoom-chats with Nelson Pass again, yesterday (in 2 parts)
|
