[paradoxper]

Whoops! I thought cfa3 was current amplification. Is it classic voltage amplification?

The CFA3 is a current feedback diamond output buffer.

 

[eskamobob1]

The CFA3 is a current feedback diamond output buffer.

Tyvm for the info.

Do you know if the kg transconductance was rectified to voltage output? Or was it true current drive?

 

[paradoxper]

Tyvm for the info.

Do you know if the kg transconductance was rectified to voltage output? Or was it true current drive?

It seems you may be conflating and not understanding the architectures here. The Transconductance is a V to I stage.

 

[eskamobob1]

It seems you may be conflating and not understanding the architectures here. The Transconductance is a V to I stage.

Correct. The amplification is then performed in the current domain. Almost always though, after the amplification stage, the signal is rectified back to voltage driven output (so the amp has normal output impedence instead of 100k ohm +). Another way to ask is just, do you have any idea what the OI of the KG transconductance amp was?

 

[paradoxper]

You need to read up on what the architectures of what transconductance is, what current feedback is, what current mirrors are as I think you are confused.

100k.

 

[K3cT]

Nice write up @Nostoi! Reading this takes me down the memory lane because the predecessor HDA5210-MK3 with the weird elongated chassis was quite a huge deal in our local audio circle since it was one of the few amps that could drive the HE-6 well. If my memory is correct the MK3 sounded more to the euphonic side of things and the voltage out was pretty much useless because it added an unnatural bass boost to many headphones and as such, it only worked well with low impedance headphones especially planars. It's a shame that it didn't really take off because it was a single ended design by nature (IIRC) and the MSRP was on the high side, making it hard to compete against the likes of GS-X, Liquid Gold, Mass Kobo 393 etc.

 

[Nostoi]

Nice write up @Nostoi! Reading this takes me down the memory lane because the predecessor HDA5210-MK3 with the weird elongated chassis was quite a huge deal in our local audio circle since it was one of the few amps that could drive the HE-6 well. If my memory is correct the MK3 sounded more to the euphonic side of things and the voltage out was pretty much useless because it added an unnatural bass boost to many headphones and as such, it only worked well with low impedance headphones especially planars. It's a shame that it didn't really take off because it was a single ended design by nature (IIRC) and the MSRP was on the high side, making it hard to compete against the likes of GS-X, Liquid Gold, Mass Kobo 393 etc.

Thanks, glad it was useful. I've not heard MK3, though indeed I'm glad they moved from elongated to square chassis on MK4. And yes, on the voltage side there's some of a bass boost on both MK4 and also the HPA-21 (this is partly why HD800s pairs nicely on the voltage side with these amps). Otherwise, I seldom touch the voltage output. I did try a 600Ohm pair of DT990's last night on the MK4 and the results were very good, but as you say this is a planar-oriented amp.

As for taking off, Bakoon Products (aka Bakoon Japan) is very popular in Asia and beyond, it's just that Bakoon International (aka Bakoon Korea) became the more well-known side of Bakoon and arguably has/had a more appealing aesthetic design to Western markets. One of the problems is that Bakoon Products are very hard to buy locally unless you import from Japan or Australia. Added to that, the Bakoon Products webpage is hardly a resource of up-to-date information. My sense is that like Mass Kobo, the owner of Bakoon Products is basically a one-man operation. Marketing is likely not his forte.

In any case, I really hope other Head-Fi members get to demo the HDA-5210MK4. It's a very special amp, indeed.

 

[jonathan c]

I notice that on the W.A.R. Audio website, the MK4 ‘shown’ has an elongated not square chassis. Also, which ‘circuit board’ and ‘gain controller’ options did you select? [I find the HDA-5210 MK4 to be fascinating. I might have to add another planar h/p to the ‘stable’: since I love the Gjallarhorn JM Edition original, it would likely be Rognir…]

 

[Nostoi]

I notice that on the W.A.R. Audio website, the MK4 ‘shown’ has an elongated not square chassis. Also, which ‘circuit board’ and ‘gain controller’ option did you select? [I find the HDA-5210 MK4 to be fascinating. I might have to add another planar h/p to the ‘stable’: since I love the Gjallarhorn JM Edition original, it will likely be Rognir…]

Yup, the W.A.R. Audio website is also not accurate (he told me he'd be updating the website soon). Rest assured, it's the MK4 with the chassis you can see in the photos on this thread. I understand by default it comes with the UL board (indeed I think that's the only option). I have the metal film gain controller. The information on the Japanese distributor here is more accurate.

Glad to hear you're pondering it. If you're interested, I'd advise contacting Pat at W.A.R. Audio despite the DIY website (price is likely going to be more competitive than Exclusive Audio).

I am listening with Rognir and 5210MK4 as I write this. The synergy is truly magical - immersive, precise, layered, spacious, dynamic, and very engaging.

 

[jonathan c]

Yup, the W.A.R. Audio website is also not accurate (he told me he'd be updating the website soon). Rest assured, it's the MK4 with the chassis you can see in the photos on this thread. I understand by default it comes with the UL board (indeed I think that's the only option). I have the metal film gain controller. The information on the Japanese distributor here is more accurate.

Glad to hear you're pondering it. If you're interested, I'd advise contacting Pat at W.A.R. Audio despite the DIY website (price is likely going to be more competitive than Exclusive Audio).

I am listening with Rognir and 5210MK4 as I write this. The synergy is truly magical - immersive, precise, layered, spacious, dynamic, and very engaging.

Just a few more connection queries since you have the MK4 up & going. Do you have your DAC / source plugged into the lower (bnc) / SATRI sockets? Has overload been an issue? The DAC that I use has output of 2.5v (SE) and 5.0v (XLR).

 

[Nostoi]

Just a few more connection queries since you have the MK4 up & going. Do you have your DAC / source plugged into the lower (bnc) / SATRI sockets? Has overload been an issue? The DAC that I use has output of 2.5v (SE) and 5.0v (XLR).

My DAC [Qutest] is plugged into the voltage (aka RCA) inputs. It seems it is possible to connect from the Qutest's BNC input to the amp's SATRI sockets, but when I asked about this on the HPA-21, it wasn't advised. In short, you need a SATRI DAC to take advantage of the SATRI socket (on this point, I am half contemplating getting this Bakoon DAC at some point, though basically I'm very happy with the Qutest, so not in any hurry). In terms of output, both 2v and 3v work perfectly well on the MK4, so you'll be fine on SE. No clipping/overload at all on 3v. The amp is, of course, SE only so your XLR would not play a role here.

 

[jonathan c]

My DAC [Qutest] is plugged into the voltage (aka RCA) inputs. It seems it is possible to connect from the Qutest's BNC input to the amp's SATRI sockets, but when I asked about this on the HPA-21, it wasn't advised. In short, you need a SATRI DAC to take advantage of the SATRI socket (on this point, I am half contemplating getting this Bakoon DAC at some point, though basically I'm very happy with the Qutest, so not in any hurry). In terms of output, both 2v and 3v work perfectly well on the MK4, so you'll be fine on SE. No clipping/overload at all on 3v. The amp is, of course, SE only so your XLR would not play a role here.

• That is great information. I would connect my DAC via the voltage sockets; getting a SATRI DAC is not ‘in the stars’ vs the Mojo Audio EVO Mystique (!)
• And, with a few calculations relating to JPY and AUD versus USD as well as your advice, it may be time to enlist and go to WAR (Audio) ………

 

[Nostoi]

• That is great information. I would connect my DAC via the voltage sockets; getting a SATRI DAC is not ‘in the stars’ vs the Mojo Audio EVO Mystique (!)
• And, with a few calculations relating to JPY and AUD versus USD as well as your advice, it may be time to enlist and go to WAR (Audio) ………

Good to hear! Quite, I'm sure the Mystique would be an excellent DAC pairing with the MK4.

Hope it goes well with WAR and hope he still has one in stock - do keep us posted!

 

[TheMiddleSky]

Nice to see more coverage about Bakoon Japan! I have heard the HDA5210mk3 (only headphone out), SCA7511mk3 (headphone out + speaker out) and PRE7610mk3 (headphone out and pre-amp out) since many years ago (I think 2013) for several times, and now decided to keep the PRE7610mk3 as i think best of the bunch in technical performance. Definitely an unique product! (And also keeper).

My PRE7610mk3 also using the WTT Metal Film and Satri UL upgrade. Really curious how 4th generation compared to the older one! PRE7610 also rated at 1W of power, and easily drive Diana TC with authority, control, and definitely could go really loud if needed (my usual volume is 12 o'clock at maximum). Diana TC is 69ohm/90dB, so definitely not easy to drive.

2. Usage: You can read more on the specs here, but a couple of points. The volume knob - controlled by a metal film attenuator - is a 23-step control. This means, it "clicks" with each step rather than rotating in one smooth motion. In practice it works exceptionally well with planar headphones, though this is not the amp for IEMs. Incidentally, the volume knob has a very satisfying tactility. I believe it's made from bakelite. While there is a notable resistance to each gain step, it's satisfying in hand.

As per my understanding, one of the most unique feature from Bakoon is they don't use "literal" volume potentiometer. The knob on Bakoon called as Gain Control, because basically it is a gain control. So, the amp has 23 gain switch to control loudness (most of other amps only use 2-3 step of gain control), and bypass the needs of potentiometer. Shorter path = cleaner sound.

 

[Nostoi]

Nice to see more coverage about Bakoon Japan! I have heard the HDA5210mk3 (only headphone out), SCA7511mk3 (headphone out + speaker out) and PRE7610mk3 (headphone out and pre-amp out) since many years ago (I think 2013) for several times, and now decided to keep the PRE7610mk3 as i think best of the bunch in technical performance. Definitely an unique product! (And also keeper).

My PRE7610mk3 also using the WTT Metal Film and Satri UL upgrade. Really curious how 4th generation compared to the older one! PRE7610 also rated at 1W of power, and easily drive Diana TC with authority, control, and definitely could go really loud if needed (my usual volume is 12 o'clock at maximum). Diana TC is 69ohm/90dB, so definitely not easy to drive.


As per my understanding, one of the most unique feature from Bakoon is they don't use "literal" volume potentiometer. The knob on Bakoon called as Gain Control, because basically it is a gain control. So, the amp has 23 gain switch to control loudness (most of other amps only use 2-3 step of gain control), and bypass the needs of potentiometer. Shorter path = cleaner sound.

Thanks, wasn't aware the gain control is a feature of Bakoon Japan more broadly. It took me a little by surprise but in practice it works well and allows for exact precision. And contrary to my remark above, it is possible to drive IEMs from this amp (IE900 in this case) without issue. Clean sound, indeed.

To be honest, some of the technical aspects of the design are lost on me, but hearing this amp, I have complete confidence in Akira Nagai's design, philosophy, and implementation. It's the only amp I've owned or heard that I find hard to stop listening once I've started.