Solid-State Power Amp Adventures

Discussion in 'Power Amps' started by purr1n, Jan 24, 2017.

  1. Thenewerguy009

    Thenewerguy009 Friend

    Friend
    Joined:
    Oct 11, 2015
    Likes Received:
    385
    Trophy Points:
    63
    The case of the amp probably are why it's so expensive & heavy. If they just used a cheap casing, it probably could have been sold at a more resonable
     
  2. zonto

    zonto Friend

    Friend
    Joined:
    Sep 30, 2015
    Likes Received:
    4,327
    Trophy Points:
    113
    Location:
    Boston, MA
    Wonderful prose from Mr. Andrew Robinson there. In my experience, that website is pretty much garbage except for Terry London's reviews. Also, what's the point of going with Class D for a mere 70W at 8 ohms? :rolleyes:
     
  3. spwath

    spwath Hijinks master cum laudle

    Friend BWC
    Joined:
    Dec 13, 2015
    Likes Received:
    7,716
    Trophy Points:
    113
    Location:
    Madison, WI
    Is the Ashley FTX-2001 any good? There is one at a local pawn shop for $150, thinking about getting it for my big jbls, my current 150w/channel amp gets near clipping levels at parties sometimes. Not quite at clipping, but close.
    They actually have a pair of them, but no way I need that much power of them bridged mono. Unless I could get the pair cheap...
     
  4. iFi audio

    iFi audio MOT iFi Audio

    Joined:
    Oct 3, 2017
    Likes Received:
    1,176
    Trophy Points:
    113
    Location:
    Many places.
    Home Page:
    Ain't that bad if done right. There's potential there.
     
  5. dBel84

    dBel84 Friend

    Friend
    Joined:
    Sep 27, 2015
    Likes Received:
    2,773
    Trophy Points:
    113
    I thought this thread best suited my ramblings instead of starting another power amp thread.

    I find it more and more challenging to compare gear as I get older, not only because there always seem to be more things that need to get done with the few hours I have over a weekend but because I really like to listen to music and I get distracted from the purpose. This is probably a reflection on the fact that all the gear is good, nasty sound wouldn't last long.

    My music chain is humble - Pi based server with Pi2Media coax hat to dac , commercial OPPO disc spinner which feeds full high def signal to dac and modded U-turn vinyl spinner with Audioquest MC cart ( OEM from the folk who are now Lyra) , speakers are Maggies - 0.7i . I rotated amps through this and my desktop system ( pi-502hat to transdac ) and franken speakers (planar / longthrow sub woofer). I listened to each over several weeks before comparing.

    Some background to why I have accumulated so many amps ... with Cavalli hanging up the reigns, there are fewer new concept ideas to try out and my usual "destress" soldering therapy needed a new outlet. I had a few things I needed to fix but as it has always been a passion to build some of Nelson Pass's ZEN concept amps, I have been picking up odds and ends to put some of these projects together.

    I have "only" built 3 of the amps - The M2 as well as the SIT based amp loosely modeled after the M2 and then an early Pass design, the Aleph. These are all 20-25W Class A amps and have some unique design aspects which attracted me to them. Well not the Aleph, I happen to have stumbled across a guy selling the boards and FETs for 1/2 the parts value and couldn't resist. I have an F3, F5 turbo and F4 sitting in the shadows - they may or may not see the light of day.

    I was chatting to zero a while back and we got chatting about the greatness of the Aegir - I thought it was worth checking out and seeing how real inefficient Class A compares to the Class A nearness of the latest continuity design from Schiit.

    The stack : Top to bottom - Aegir, DIY PASS/First Watt - M2X, Mini Aleph, Sissy SIT

    [​IMG]


    [​IMG]


    [​IMG]


    The Pass amps sound of similar ilk - there is a smoothness and effortless transparency which I have come to take for granted with these amps. They err on the warmer side but in no way are less resolving. The top performer is the SIT amp - it harkens back to my "stacker" which, for those who heard it, will understand this reference. It melts into the background, leaving you immersed in music which is fleshed out and you have no choice but to submit to the experience. The M2X is similar but not quite as "hair raising", it has a front end buffer which can be played with to change the sound - there two opamp based input boards, one buffered the other not; a fully discrete BJT buffer and the original JFET - I did not play with buffers. The M2X errs more on the warm than SIT which is the least "warm". The Aleph was a pleasant surprise for me when I initially built it, I wasn't expecting much given how relatively old the design was. I have 2 ADCOMs which I have modified (yes - I do have way too many amps) and I had anticipated a similar level of performance to these amps, it is closer to the Aegir in the sense that it offers a more forward soundstage but digs deep into the bass with a lot of control. I built the simplest version of the Aleph -I have an additional daughter board which parallels another 3 pairs of output devices - psu could handle it easily but I would need beefier heatsinks if I kept the bias up ( I built mine with higher rail voltages and higher class A bias compared to the standard build hence 20W and not the 10W it would have been --- the Aleph 30 which is what it was designed to be is a 30W Class A amp)

    Aegir - there have been many great reviews praising the virtues of this amp and no less deserving. It is surprisingly heavy for it's smaller size. Marv nailed the description of the sound, I had not really read the details of his review until after I had heard the amp and he echoed many of the mental notes I had made while listening. Vocals are projected with natural timbre, and everybit as resolving as the classic Class A amps. The overall sense of the amp is its forward character, not saying that it is a monolayer, it textures beautifully with great resolution and detail. Schiit aimed to achieve that special magic of Class A and they succeeded. My one gripe is that bass does not have the same presence. (with the sub engaged and tuned for this playback rig, it was a thoroughly engaging experience). In comparisn, all the FW amps are well balanced and effortless. This could be speaker compatibility or stereo vs mono etc but my intent was to take a 20W amp and play it in my system.

    My conclusion to this exercise is that my personal sound preference is for the First Watt based amps, but they get hot and need a lot of air to breath. The Aegir in comparison hardly warmed up, so running 2 of these next to each other would still generate less heat than any of the others. Cost - you cannot compete with the Aegir, build cost for the SIT amp was 1.5 x even with me being extremely frugal. The Aleph, I got lucky and managed to build it on a shoestring so it cost less but not by much.

    I don't think this opinion is going to help many folk as the DIY amps are pretty much one offs but it should help anyone doubting the capability of the Aegir, add a sub to fill in the bottom and be very happy.

    ..dB
     
  6. purr1n

    purr1n Burned out

    Staff Member Friend BWC
    Joined:
    Sep 24, 2015
    Likes Received:
    81,281
    Trophy Points:
    113
    Location:
    Padre Island CC TX
    Thanks Don for comparisons to the various classic Pass amps. The Aleph was one of my favorites back in the day, so it's interesting to see how it stacks up. I'm still tempted to pick one up, but you know how it goes, too much gear in the house.

    I agree with your impressions that the Aegir doesn't have quite that oomph in the bass. It's going to be system dependent, but on my big JBLs, I could use some of that bass presence (contrary to what people think about speakers with big woofers, the 4698b are a bit on the lean side - plenty of heft, but slightly lean. This is to be expected from woofers with 0.2 Qts though.)

    Now you know why I've been asking Jason every month to make an even bigger Aegir with the Nexus stage in front. I currently stick a Freya S pre (with the Nexus) stage in front to the Aegir. But as with all active pres, we lose a little bit - errors of omission. The Nexus stage has a certain sound, bassy and richer, and when implemented with some gain, deeper stage. All these things complement the Aegir well. I'm really just nitpicking. Running Aegir with a cheap passive pot most of the time.
     
    Last edited: Nov 11, 2019
  7. JeffYoung

    JeffYoung Friend

    Friend
    Joined:
    Apr 11, 2017
    Likes Received:
    700
    Trophy Points:
    93
    Location:
    Ireland
    Thanks for posting that, dB. Funny thing is I've never tried my DIY F3, F5 or J2 on my Maggie 0.7s. The Maggies are in a big room (20x30' w/15' ceilings) and I just figured the FirstWatts wouldn't have enough output. Sounds like I should at least see what it's like.

    Cheers,
    Jeff.

    The plus side is I'm in Ireland. I just turn off my class A amps for both days of summer. ;)
     
  8. dBel84

    dBel84 Friend

    Friend
    Joined:
    Sep 27, 2015
    Likes Received:
    2,773
    Trophy Points:
    113
    Do it and let us know your thoughts - The F3/Zen9 has interest as a higher power jfet sound as I don't see myself risking buying fake semi's . If you manage to get those FW extrusions made, then a ZM J2 construction might be the next serious build. I will even have the Burning Amp "This is the LAST amp" T-shirt made ;)

    ..dB
     
  9. JeffYoung

    JeffYoung Friend

    Friend
    Joined:
    Apr 11, 2017
    Likes Received:
    700
    Trophy Points:
    93
    Location:
    Ireland
    OK, so the F5 does indeed run out of steam, but not by as much as I would have thought.

    It's both a gain issue and ultimately a power delivery issue. If I connect the F5 directly to the output of my Onyx it runs out of gain; if I insert my DIY HPA-1 pre into the chain (8dB of gain), the F5 clips at higher volume.

    Room is 20' x 30' with 15' ceilings. Magnepan 0.7s. Listening position is 20' from each speaker; speakers are 22' apart.

    The F5, being push-pull, will go into class AB pushing 4 ohms. Since the F3 and J2 (being single-ended) won't, I didn't even try them. I can't really differentiate amps at lower volumes.

    So the Maggies (in my room) really do need on the order of 100W. But I've got a solution for that cooking:

    beefcake-small.jpeg

    I just need to figure out how to get the slew rate up without severely unbalancing the LTP....
     
  10. Forza AudioWorks

    Forza AudioWorks MOT: Forza AudioWorks

    Joined:
    Jun 20, 2017
    Likes Received:
    381
    Trophy Points:
    93
    Location:
    Poland
    That Pass tho. I have FirstWatt F7 and it rocks!
     
  11. dBel84

    dBel84 Friend

    Friend
    Joined:
    Sep 27, 2015
    Likes Received:
    2,773
    Trophy Points:
    113
    thanks for trying. this is why "apples to apples" can be golden delicious to granny smith doesn't have to be a pineapple comparison. My setup is much more intimate - panels are about 3 feet from the back wall, roughly 25 deg toe-in , ( I am guesstimating ) 15 feet apart with sweet spot about 12 feet from center. I know my source tends to be be hot ~ 3.5V and even with a unity gain buffer in front , I am hard pressed to go beyond 12 or 1 O'clock on the volume. As a general rule I listen at lower volumes - there is a lot of nuance and control that is apparent ( to me in my system ) = I am the guy with the earplugs at all live concerts :) ..dB
     
  12. JeffYoung

    JeffYoung Friend

    Friend
    Joined:
    Apr 11, 2017
    Likes Received:
    700
    Trophy Points:
    93
    Location:
    Ireland
    OK, I lied. I left the F5 hooked up because I was just listening to background music. And after a couple of hours, I have to retract my statement regarding differentiating amps at lower volume levels. The F5 sounds quite different from my Cronus Magnum II on some tracks. On the odd few I hear things in the treble that I had never noticed -- and I'm not even in the listening position. And on a lot of the tracks the mid-bass is more groovy: it's like the difference between a real earthquake and a Hollywood one: more (tight) rolling waves; less shaking & rattling.
     
  13. elmoe

    elmoe Friend

    Friend Banned
    Joined:
    Apr 23, 2019
    Likes Received:
    954
    Trophy Points:
    93
    Location:
    Phoenix, AZ
    That's an interesting description of how the bass changed. I felt the same going from a Vidar to a McCormack. Not more bass, just better all around.
     
  14. Forza AudioWorks

    Forza AudioWorks MOT: Forza AudioWorks

    Joined:
    Jun 20, 2017
    Likes Received:
    381
    Trophy Points:
    93
    Location:
    Poland
    Which speakers do you have if I may ask?
     
  15. JeffYoung

    JeffYoung Friend

    Friend
    Joined:
    Apr 11, 2017
    Likes Received:
    700
    Trophy Points:
    93
    Location:
    Ireland
    dB and I both have Magnepan .7s.
     
  16. Forza AudioWorks

    Forza AudioWorks MOT: Forza AudioWorks

    Joined:
    Jun 20, 2017
    Likes Received:
    381
    Trophy Points:
    93
    Location:
    Poland
    Cool, thanks!
     
  17. yunie_

    yunie_ Acquaintance

    Joined:
    Mar 13, 2018
    Likes Received:
    69
    Trophy Points:
    28
    Location:
    Singapore
    I was reading through one of my local forum and saw a guy buying isoacoustics orea for his hegel h160, and thought that is the stupidest thing I ever seen someone done, especially since hegel h160 already has rubber feet.

    but on googling, i realise that there are many other people doing the same thing. buying extremely expensive isolation platforms for their amp. the argument is that the transformer in the amp is mechanical and therefore, requires isolation.

    so am I that idiot, or are they really stupid?

    [​IMG]
     
  18. msommers

    msommers High on Epipens

    Friend
    Joined:
    Nov 6, 2016
    Likes Received:
    2,741
    Trophy Points:
    113
    Location:
    Calgary, Alberta
    Home Page:
    You're silly for asking and they're idiots for actually spending any money.
     
  19. atomicbob

    atomicbob dScope Yoda

    Friend BWC MZR
    Joined:
    Sep 27, 2015
    Likes Received:
    16,392
    Trophy Points:
    113
    Location:
    On planet
    Mechanical damping is useful but need not cost a fortune:
    https://www.amazon.com/gp/product/B00006HTZ0/

    I use these pads in my lab. They provide both vibration damping and prevent surface marring when stacking components.
     
  20. Thenewerguy009

    Thenewerguy009 Friend

    Friend
    Joined:
    Oct 11, 2015
    Likes Received:
    385
    Trophy Points:
    63
    From my limited perspective. I noticed the heavier/denser the feet are, the better they isolate.
     

Share This Page