Fosi Audio ZA3 - Class D Done Right

Just a heads-up to anyone who might run into the problem that I had, if you have a DAC directly connected to the ZA3, and you're hearing very audible distortion on some songs, you need to use a preamp in-between the DAC and ZA3.

This is my 2nd experience with a passive 2 channel set up, so I wasn't aware this was a thing and could happen. Was getting pretty bad distortion (crackling/crunchiness) and thought it was either the new speakers or the ZA3, turns out it was the Cyan 2's hot output through XLR. Using the Midgard as a preamp fixed it completely.

 

Yeah, that would work. Measure the FR out to 100khz or so to see the whole filter response.

 

I think all top end class D sound identical because they are just wires with gain, they makes zero change to the sound. In case you want to bitch about Purifi I've made a separate thread on them, however anything said in this thread about Fosi applies in full to purifies as well, except they are even more like a wire with gain. My thread: https://www.superbestaudiofriends.org/index.php?threads/purifi-purifi-vs-aegir-purifi-vs.14968/

 

Please before giving me another negative rating I will never claim that class D can compete with good AB even less A. It is mostly about price/performance where high power matters. Class D cannot compete with AB/A where 50W is enough. If you know for sure 50W will never clip for you any class D should be out of consideration. But I am afraid beyond 50W the AB price takes off exponentially and the P/P game turns 180 degrees pretty soon.

 

Pedantically: the "respectfully disagree" is a neutral rating and actually doesn't count against the negative ratings total if you give that a glance. Also, it's just opinions about audio gear here-- nothing worth stressing about, and sometimes (when everyone involved has the mental bandwidth to spare) it can even lead to interesting discussions.

I've got less experience with lots of amps than most of the active members here but from what I can tell yeah there's definitely a "sound" to each of them so it's not as if it's just class D that stands out in this respect. I think folks have also recently opined that modern class D stuff was sounding MUCH less restrained and insipid compared to earlier designs-- this gives me some hope for sanity because of the greater efficiency inherent to it.

For context it's 34C/93.2F outdoors right now with a UV index of 11 and I'm getting painful rashes from the heat; even if I had the physical space for a BIG IRON (anyone else remember JJ, hah) amp in my listening space, the heat may end up being the death of me. Who the crapcakes says that anthropogenic climate change is a myth?

 

I have never heard this Fosi amp, but I own a marantz model 30, it is class D and it sounds great. Way more money than the Fosi! It even has an integrated phono preamp that I think sounds really good. Better than my parasound z phono. Enjoy what you enjoy! Music is what I use gear for...

 

So my little 100-dollar Fosi is a perfect amplifier?

Wooo... Who'd have thought I'd end up with such a thing because, given the state of my hearing, I don't spend real money on audio any longer! Ironic

 

@androxylo , I have read a bunch of you comments. It seems to me you try to die of the hill of each thought.People here have strong opinions, but most are open to the discourse that their comments bring on. life is good, read posts, post posts but try to relax and enjoy the dialogue. If you want to argue here people will rise to the challenge, but I think it's better if you don't get so butthurt sounding. No one is here to quibble over your every thought! Stay calm and forum on.

 

I apologize, in the hindsight I think I was not contributing to the discussion after 1 or 2 posts. I think I triggered some topics that were interesting for me but I don't really have much value to add.

 

I don't think it's the topics, is more in the delivery of the topic and responses that seem argumentative, to me at least. The people on this thread live to learn and teach, don't be afraid to ask questions, just don't bristle at opposing arguments!

 

will also add that your "wire with gain" statements about class D was sure to garner disagreement. For the most part, people at SBAF don't believe in "wire with gain"... everything tends to have a sound.

 

I would add that everything in a chain of disparately engineered and produced goods exist as a collection of compromises. Plugging our audio gear together to listen to music is really just a Maximin or Minimax exercise in pursuit of individual art appreciation/finger painting class.

 

I mostly disagreed with the statement that all high end Class D sounds the same and theme there is the additional that this sound is transparent. I would say Class D has made leaps and bounds the past 5-10 years. Pro audio definitely was first, but many of the hi-fi chips are made by the same manufacturer (TI), but I have heard three TI amps with the same chip and they all sounded completely different. And even after all that, I am back to a vintage class A/B amp that seems more dynamic with more depth and just so much more robust sound than any of the Class Ds, and it’s only 35 watts.

But basically, over generalized statements won’t fly very far around here.

 

I changed the opamp of fosi Za3 from NE5532 to OPA1612, strangely the background noise when installing OPA1612 is louder than NE5532.

I thought OPA1612 is the opamp with the best parameters and cheap price (I bought 2 pairs for 8$ from my friend), but the background noise is louder.

 

God damnit every time I see this thread I think it's something exciting about 2a3 tubes.

 

Has anyone competent had a play with those little v3 monoblocks? I saw a couple of other threads, but they reeked strongly of head-fi dotard. I could walk around the corner and pick up a pair on a whim for troublemaking reasons, but feel like I'd rather not piss money up the wall if they're pants. Yes, OK, maybe I'm bored and want toys.

If I end up with a pair of Gjallarhorns for the relatively sensitive speakers kicking around, I might have to tidy up to get them on the shelves. Ain't nobody got time fo' that.

 

Ok, well, following on from the previous post.. I might have accidentally a pair of the v3 monoblocks and they're TINY.



(This thread might not be ideal, but the other thread someone made for these things gives me the ick. Sorry about that.)

I'm using them in quite an impressively untreated room, with some inexpensive old 89? or so dB sensitivity Mordaunt-Short bookshelves on stands, so it's hardly a an ideal situation to opine on subjective sound quality. Which is what I'm probably going to do anyway.

I dug an old first gen Jot out of storage and am feeding it single-ended from a Modi 3e (very D/S) and then balanced out of the Jot into the monoblocks. There's a powered sub on the single-ended outs of the Jot, to keep things similar to how the room is normally used.

So far it's not horrible, though the Jot was possibly making the FR sound a bit too forward in high gain. I wasn't sure if it was just my ears. I went back and forth between that lot and a Sony WM1a with UERMs to remind my brain of what "normal" FR sounds like for me, which made me think that maybe it was a bit much.

The first gen Jot can be a bit bullish anyway, but low gain on the Jot was a little less forward in the upper mids etc.. Hard to know where to apportion blame though, I don't normally use that Jot as a pre,

Anyway, FR was tolerable with the Jot in low gain and the speakers seem to be gripped nicely. Nothing is too fatiguing, there's a bunch of detail, crisp transients and importantly, shit's in phase (poor QC on early units apparently made this a crapshoot).

I'll leave them going this evening for a while, see how they fare, with particular attention to how hot they get, as there seems to be chatter about that. Lots of layered detail to be had in classical recordings that I know well, and things like good crisp transients in a couple of rock tracks I know well. Some french breakcore sounded on point. So far so... acceptable?

 

Update, after a few hours of playing music at socially acceptable volumes and about 3m range, they run warm, but nothing too shocking.

 

Continuing to bloat this thread, but you know what those little Fosi monoblocks really like? A Saga 2.



So that's a Modi 3e (very D/S) into the Saga 2, obviously single-ended. The XLR outs of the Saga into the monos and the RCA outs going to a little 80W powered Mordaunt Short subwoofer. Cheap stuff. I did take the time to dig out the measurement mic and adjust the subwoofer a bit (while ignoring the slightly alarmingly uncontrolled room modes) just to give it all the best chance.

Gone is the slightly metallic sheen of the Jotunheim, also the slight stridency the combo produced in high gain. In contrast, the Saga 2 really makes it all come to life in its high gain mode, elevating the dynamics, both macro and micro. You can hear the tension in the strings of a bass guitar or the tons of Leslie speaker used on Dark Side Of The Moon without difficultly.

Detail is surprisingly good, clear without being tiring. The crunch of a distorted bass amp has a ton of texture without being grating. The transients in the individual strikes on a Timpani deep in my favourite recording of Jupiter from The Planets are clean and realistic-sounding- you can actually hear what he's doing.

Metal strings sound like metal strings.. but not all strings sound like metal strings (if that makes sense). Bicep's "Glue" doesn't suffer from those airy gated vocal pads sounding harsh, yada yada.

Without waxing too lyrical, they scale better than I expected with a change of preamp, no notable sins of omission or commission. Nothing sounds too thin or piercing and crucial timbres like pianos or voices aren't weird. I can hear a shocking amount of detail and spatial clarity in some big orchestral recordings.

I'm trying to resist the urge to find and plug in the Gungnir Multibit, as I suspect it'd sound rather nice here. It might be worth picking up a Mimir for this little setup when the UK dealer gets some, to benefit from that filter. I'm trying to avoid kit that needs leaving on, both for power consumption and heat reasons, which is why I'm back on D/S now despite myself. I can hear a little harshness and characteristic D/S prickle if I push my luck and listen to "Some Girls Wander By Mistake" by the Sisters Of Mercy, though that album is like listening to a razor blade on the best of systems too.

This feels like a kickass budget setup, but there's every danger it will become a bit of a ship of Theseus. Somewhere down the line, I could see myself tempted by new speakers and some <looks around shiftily> Hypex-based monoblocks.