Hi Eric - Thank you, that's very kind. At another member's suggestion (after seeing me struggle mightily to use other solutions) I purchased a QuantAsylum 403. Not everyone's situation will be similar, but I'd consider myself reasonably adept and willing to learn. I evaluated testing laboratories and test methods in a different field of expertise for a portion of my career. Yet... where others found great success with many other methodologies which I tried to mimic... I couldn't ever get results I was thrilled with, and the process was (to me) cumbersome. So, I wound up spending about 1/2 of what I had already invested in distortion analyzer(s) and other tools and got the 'one stop shop' solution. I was up and running with what I'd consider reasonable results within two days vs. a year (on and off) struggling to learn with other solutions and write a process to achieve good results. Is there a learning curve? Sure. With that said, the automated scripts built into the software are a dream. My 10 pages of documentation and a process that used to take 4 or 5 hours + analysis to run a set of measurements now is down to 1 page of "reminders" and only takes about an hour including analysis and filing my summary documents. In another thread when someone asked me (before it had arrived) why I was buying the QA when I already had Products X,Y, and Z... I used the analogy of cars. I had/have a Ferrari F40. It's vintage, beautiful, powerful, and in the right hands will outperform most modern cars. However, me likey some computer assist. Makes an OK driver produce repeatable and predictable results and limits the chances of binning the car.
@tubesguy - Thanks to you as well. Apologies. @rhthatcher is THE Randy.
@Eric - One thing I didn't mention that I'll admit to openly...
I had fooled with a few solutions for measurements since I started this hobby in 2019 (oddly that's when I saw a QA at BAF). However, one of the many reasons I've been more intent to learn how to measure properly for the past year, is that I've often wondered if some of my builds were actually functioning as intended.
With a few voltage checks here and there, we can be generally sure, and this stuff is sooooooo fun to build. I just assembled, assembled, assembled. However, I don't love all the amps that others love, and sometimes I wondered if I built them properly.
There are a few that make music, and some I don't love as much as others, and some I don't think perform quite like I think Papa intended... So, I need to put my thinking cap on. Really it just comes down to trying to learn if anything from a measurement standpoint aligns with what my brain says sounds wonderful. I'm also experimenting with measuring my "full chain" vs. just amps and pre-amps separately. That's another whole can o' worms. Papa replied to one of my comments early on (I think it was in the H2 thread) when I asked if a pre-amp produces a negative H2 and and amplifier produces a positive H2, will they cancel. He said yes.... and... yes... they do. Using the QA makes measuring 'on a whim' easy.
OK - I'll give my fingers and everyone's eyes a rest.
I had fooled with a few solutions for measurements since I started this hobby in 2019 (oddly that's when I saw a QA at BAF). However, one of the many reasons I've been more intent to learn how to measure properly for the past year, is that I've often wondered if some of my builds were actually functioning as intended.
With a few voltage checks here and there, we can be generally sure, and this stuff is sooooooo fun to build. I just assembled, assembled, assembled. However, I don't love all the amps that others love, and sometimes I wondered if I built them properly.
There are a few that make music, and some I don't love as much as others, and some I don't think perform quite like I think Papa intended... So, I need to put my thinking cap on. Really it just comes down to trying to learn if anything from a measurement standpoint aligns with what my brain says sounds wonderful. I'm also experimenting with measuring my "full chain" vs. just amps and pre-amps separately. That's another whole can o' worms. Papa replied to one of my comments early on (I think it was in the H2 thread) when I asked if a pre-amp produces a negative H2 and and amplifier produces a positive H2, will they cancel. He said yes.... and... yes... they do. Using the QA makes measuring 'on a whim' easy.
OK - I'll give my fingers and everyone's eyes a rest.
IAIMH,
The Sony Vfet amp is truly wonderful. Regarding measurements and sound expectations, I can tell you from my personal experience that most of the time the amp is delivering less than 1w and you should do the FFT at 1/4W going up, which would be more meaningful. I see the H2 dominant at that level and as you incresse the power output it changes to H3 dominant.
Like WBS, I am using it to drive the tweet and mids of my OBL15 and F5TV3 for bass.
I have just introduced the ZM Iron Pre into this setup and it mates very well. Unlike most actives, the Iron Pre instrument timbre is full, not thin, and the music has body and life to it.
nash
The Sony Vfet amp is truly wonderful. Regarding measurements and sound expectations, I can tell you from my personal experience that most of the time the amp is delivering less than 1w and you should do the FFT at 1/4W going up, which would be more meaningful. I see the H2 dominant at that level and as you incresse the power output it changes to H3 dominant.
Like WBS, I am using it to drive the tweet and mids of my OBL15 and F5TV3 for bass.
I have just introduced the ZM Iron Pre into this setup and it mates very well. Unlike most actives, the Iron Pre instrument timbre is full, not thin, and the music has body and life to it.
nash
^ Great suggestion!
I had a little 'play time' available. So, I ran a few measurements. Your observations match mine. Note, I did not do any replicates, and admittedly this was rushed. So...
I found the level roughly where the distortion emerged from the 'noise floor'... I considered the noise floor above the highest peak in the audio band from the PSU. Now... whether that distortion is audible or not.. I dunno. I don't want to even be a part of a subjectivist objectivist discussion. I just love fooling with this and learning a little along the way. Plus a few of you indulge my long posts with a like every now and again... so, if someone else out there is in a similar boat and wonders about the same things... great.
Note - all of these were done with the attenuation for the QA off. That lowers the noise floor of the analyzer nicely, but ... it makes things visually look a bit of a mess. That's why I love the markers to specifically note the relative dB along with the measurements calibrated to a known voltage.
It does make me want to re-look at the PSU for this amp... nah! If it ain't broke.
Anyway... just as the distortion emerged from the noise floor at 200mW. I could have backed the power down a bit more, but it illustrates the point, I hope. Nice 2nd.
Round number of 250mW
Took a few minutes to try and find the power level where the 2nd and 3rd were close to equal... close enough for me anyway...
434mW
The previous measurement was close enough to 500mW, so I bumped to 750mW
Thanks for the suggestion. I admit that I play my amp a little louder... and have a reasonably sized room, but you're dead on that I do listen at <1W a lot, particularly in the mornings. I've always wondered a little bit why I like some amps better at lower volumes... this may give me more insight. 🤷♂️
I had a little 'play time' available. So, I ran a few measurements. Your observations match mine. Note, I did not do any replicates, and admittedly this was rushed. So...
I found the level roughly where the distortion emerged from the 'noise floor'... I considered the noise floor above the highest peak in the audio band from the PSU. Now... whether that distortion is audible or not.. I dunno. I don't want to even be a part of a subjectivist objectivist discussion. I just love fooling with this and learning a little along the way. Plus a few of you indulge my long posts with a like every now and again... so, if someone else out there is in a similar boat and wonders about the same things... great.
Note - all of these were done with the attenuation for the QA off. That lowers the noise floor of the analyzer nicely, but ... it makes things visually look a bit of a mess. That's why I love the markers to specifically note the relative dB along with the measurements calibrated to a known voltage.
It does make me want to re-look at the PSU for this amp... nah! If it ain't broke.
Anyway... just as the distortion emerged from the noise floor at 200mW. I could have backed the power down a bit more, but it illustrates the point, I hope. Nice 2nd.
Round number of 250mW
Took a few minutes to try and find the power level where the 2nd and 3rd were close to equal... close enough for me anyway...
434mW
The previous measurement was close enough to 500mW, so I bumped to 750mW
Thanks for the suggestion. I admit that I play my amp a little louder... and have a reasonably sized room, but you're dead on that I do listen at <1W a lot, particularly in the mornings. I've always wondered a little bit why I like some amps better at lower volumes... this may give me more insight. 🤷♂️
I can tell you this. I was the last to get the kits. Ordered the limit of 2. Only one pr of brackets were available for the 2 pair. Meaning 'I'm short a pair'.
I will be making my own. They are not available.
Unless you are not in a rush I can make my brackets off the originals and pass them on to you. I assume you are building just one amp? I would need some time.
That may be an option down the road.
Wow @Holzarbeiter, this community is never stopping to impress me for its generosity! 
I am not in a rush. I have 2.5 project to finish still, and in my best estimation this build will not start before the second part of the year. This project is rather special for me. When it was happening, I was away from this site for a number of reasons (changing country, starting a new job, moving house, and expecting the first child). If I can make it happen as in the original kit, it would be like I never missed a page here. And the fun is in trying, anyway.
However, I do not feel like taking from you what it seems you will need and use. I am convinced there are still people around that took two kits for the parallel VFET version. Indeed, I am still waiting an answer from a member that may still have a pair stored away. Others may show up eventually.
@von Ah good suggestion. But if I don't find the originals, I think I will make my own with the exact number of holes and in the right locations.
I am not in a rush. I have 2.5 project to finish still, and in my best estimation this build will not start before the second part of the year. This project is rather special for me. When it was happening, I was away from this site for a number of reasons (changing country, starting a new job, moving house, and expecting the first child). If I can make it happen as in the original kit, it would be like I never missed a page here. And the fun is in trying, anyway.
However, I do not feel like taking from you what it seems you will need and use. I am convinced there are still people around that took two kits for the parallel VFET version. Indeed, I am still waiting an answer from a member that may still have a pair stored away. Others may show up eventually.
@von Ah good suggestion. But if I don't find the originals, I think I will make my own with the exact number of holes and in the right locations.
Peppe,
I was only able to buy the one pair brackets in the day. I bought two amp kits for bridged Dual Mono.
Knowing I'd have to make 2 long brackets to put 2 amps in one case.
I have to get these amps done just to make sure the parts still are sound.
These NOS brackets I basically bought for the measurements.
I always wanted to say "I was short a pair". And this has been accomplished.
For the record you know at least one pair is out there if you can't find any. All I need is to get them up to the MIll and transfer the dimensions. My body is the problem. The timeline for you to decide if you need them is not an issue.
von Ah has a good solution. My only concern would be how flat they are. Even ModuShop has difficulty.
Best, H.
I was only able to buy the one pair brackets in the day. I bought two amp kits for bridged Dual Mono.
Knowing I'd have to make 2 long brackets to put 2 amps in one case.
I have to get these amps done just to make sure the parts still are sound.
These NOS brackets I basically bought for the measurements.
I always wanted to say "I was short a pair". And this has been accomplished.
For the record you know at least one pair is out there if you can't find any. All I need is to get them up to the MIll and transfer the dimensions. My body is the problem. The timeline for you to decide if you need them is not an issue.
von Ah has a good solution. My only concern would be how flat they are. Even ModuShop has difficulty.
Best, H.
OK, now I see. I will PM you.
I guess you already know, but measurements of the brackets are available few pages back. They can be useful.
https://www.diyaudio.com/community/...rated-build-guide.302380/page-62#post-6610791
I guess you already know, but measurements of the brackets are available few pages back. They can be useful.
https://www.diyaudio.com/community/...rated-build-guide.302380/page-62#post-6610791
Yeah these are out of stock. As with everything, if more people are interested into these, another group buy could be set up so more can be produced
Gianluca estimated a critical mass of 10 pairs to make a new batch.
These are not drilled holes. They are reamed to dimension. T Stock most likely is region dependant if original is required.
As always you want original there is only one with the tooling that was used in period to create.
Then the process of matching the color and texture of the anodizing.
As always you want original there is only one with the tooling that was used in period to create.
Then the process of matching the color and texture of the anodizing.