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First Watt Clone - The DIY M2

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15 hours ago, Marvel said:

Salamat, po...

 

Walang anuman po

 

 

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45 minutes ago, DizRotus said:

 

Walang anuman po

 

 

 

👌

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Well I finally completed my Pass DIY Sony VFET amplifier project. With tremendous help from Chuck, a fellow diyAudio.com member, on the Sony VFET bias settings, I have completed my build and I am very impressed with this amp with only 6-7 hours of music playback.

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As I previously mentioned, I purchased a set of untested (unmatched) Sony VFETs from wdecho that he bought from Acronman a while back. He also included a pair of the T-brackets, mica insulators and a pair of the PCBs. After budgeting my money and purchasing all the parts through Mouser, Parts Connexion, the diyAudio store and the local Ace Hardware, I set off on measuring and matching resistors and capacitors and followed 6L6's excellent build guide and Nelson Pass' instructions.

Chuck really helped me with biasing the Sony VFETs and then we set it up in his system to audition the amp. The DC offset was kept well close to 200mV on each channel with the final settings. Having a great local resource like him in the Twin Cities is a real blessing. It sounded like a freshly built amplifier on his very efficient horn speakers. We then tested it with his distortion analyzer to see how closely matched each channel was since the VFETs were not tested and matched by Nelson Pass.
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The photo shows the spectral analysis for the right channel, which looks great. To my pleasant surprise, the left channel was virtually identical to the right channel. THD on the right channel measured 0.0130% @ 1 watt, while THD on the left channel measured 0.0135% @ 1 watt. It was time to close up the chassis and take it back home to enjoy.

I plugged the amp into my system consisting of an Audio Research vacuum tube phono stage, an Audio Research vacuum tube line stage and a pair of KEF LS50 monitors.

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This amp has no problems driving the KEF's with the gain from my ARC LS7 line stage preamp. Chuck advised me to give this amp a lot of hours for it to really settle in, but I have to say that I am already impressed. The sound is so natural and clear. This is my first Pass DIY (and solid state amp) project ever, and just following Nelson Pass' documentation, 6L6's build guide on the diyAudio.com forum, and sage wisdom from wdecho and Chuck really made this project a success. 

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After about 15 hours of total play time, this amplifier is starting to settle in. The bass notes are more complete with detail, depth and sustenance. The soundstage is still growing in all three dimensions, separation and space are coming into better focus, and the dynamic range has also increased with greater slam and transient response. This is a very solid amplifier and I can certainly understand why many would prefer this amp over a tube amp. In fact, it bears some resemblance to my McIntosh MC240 6L6 push-pull stereo amp with that holographic presentation, warmth and body.

 

Even though my Forte II's are in storage, my KEF LS50's are doing a respectable job of creating room-filling sound. I can understand where many Klipsch Heritage or classic Altec horn-based speaker owners would be very pleased with an amplifier of this calibre generating 15 high quality watts into 8 ohms.

 

I have posted on these forums about my push-pull tube amps and some really good Texas Instruments Class D amps, and this Nelson Pass designed amp is one of the best in my amplifier collection. It really has the soul of a tube amp, but it also has the desirable hallmarks of a solid state amplifier. It is an incredibly musical amplifier that allows me to get lost in the music. I really cannot rank my amps, because some are in storage or just don't work well with my KEF LS50's for a fresh comparison, but what I can say is that I will be keeping this Pas DIY amp in my system for a while.

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I too built a VFET and it is my most favorite that I have built to date. I have never posted pictures on this site, but here are a few. A couple of things to note on my build is that I went dual mono, meaning two separate internal power supplies, two transformers and 4 rectifiers, although it does share one on/off switch it's mono from there. This thing is a beast and weighs in at 42#.

 

IMG_7967.thumb.jpeg.8ab8a594c2e08ee3a0c8573bafea6c3b.jpeg

 

You can see how it compares to the single power supply of the Burning Amp build.

 

IMG_7966.jpeg.99d1d649bb504910caaee6c317529716.jpeg

 

Joe

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Joe,

 

You did a tremendous job with building both of those amps. Your dual-mono Sony VFET has to be challenging with the tight quarters of the chassis. 

 

I am curious how the Burning Amp compares to the Sony VFET amp. The reason I ask is because a good friend of mine used to own a Pass Labs Aleph 3 years ago and regretted selling it. Is the Burning Amp remotely close to the Sony VFET in terms of sound quality, and how many watts does the Burning Amp output? He owns a pair of KEF Reference 101 monitors (basically BBC LS3/5A monitors with an 8 ohm nominal impedance). 

 

Rich

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Rich, I don't know what the BA-2 will put out. If I recall you can adjust the bias higher and higher and with more heatsink the more wattage you get. I also used the burning amp gain stage, which I recall is similar to the gain stage that is in the VFET. I believe that is why Wdecho suggested I try it, as I liked the VFET so much. I think the BA puts out more power than the VFET, but I am not so good at remembering the numbers (Wdecho was better at that than I, and I never could have done it without him). I remember cranking my bias pretty high, way more than 250mv, hell its called the burning amp for a reason and I am a fearless amp builder...

 

As far as side by side, I have never compared them head to head, but I suspect they are both very similar. Something to note, is the gain stage on the BA has the ability to adjust the second harmonic, which adds the tube sound or takes it away. Although I have the tools and Wdecho gave me a tutorial, I haven't yet adjusted this. What you really should do, is build the BA! They are both world class amps and the BA is a cake walk compared to the VFET.

 

My order of preference:

SIT-2 (not DIY)

VFET

BA

M2 (had both DIY and NP no I could not tell the difference)

AlephJ (which doesn't deserve to be on the bottom of any list)

 

Joe

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17 hours ago, codewritinfool said:

Yer killin’ me, Joe. Aleph-J is one of my in-the-works projects.

 

I like to think the Aleph J is like the Ford F-150 of amps, does everything well and if you only had one class A... that'd be a good one and you'll be very pleased. The others are more of a different flavor and are striving for more of a tubeish sound. The Aleph J is a good old well designed voltage source class A amp. I also like the option of balanced inputs with that build, and I used my Aleph Js ( I built a pair) on my Jubilees and they sounded fantastic.

 

I like the Aleph J better than my McIntosh MC2205 if that helps. These designs are all in a class all of their own.

 

Joe

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=== like the FW J2 and F3 I believe the Aleph J uses JFET transistors for their power source? J2 is a two stage, F3 a single stage design with less gain. I have the F3 which is a fine sounding amp with a very black background, zero noise. However it does run typically Class A hot, actually much hotter than the Class A Pass Lab XA 25. Chassis size are nearly identical but the XA heat sinks are much more elaborate which might well provide its ability to run cooler at over twice the power output. But power transistors are totally different also. The XA plays everything bigger, deeper, sweeter than the F3. (and it should) Although I am currently playing the F3 with LaScala and the combo is damn nice. I wish I had the skills to roll my own, alas I do not — 

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