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Author Topic: Bakoon HPA-01  (Read 8927 times)

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OJneg

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Re: Bakoon HPA-01
« Reply #50 on: October 14, 2014, 03:44:13 PM »

Maybe one of you guys should check out the Current Conveyor amp on diyaudio? Seems to be a awesome design for a voltage mode satri-style amp. I'm surprised it does not benefit orthos given ortho's relatively flat impedance.

http://www.diyaudio.com/forums/analog-line-level/223835-current-conveyor-voltage-amplifier.html

It's possible that other orthos might benefit from the topology that the Bakoon is utilizing. Mr. Anax only tested the....HE-5 and PM2 unless I'm mistaken.
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ultrabike

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Re: Bakoon HPA-01
« Reply #51 on: October 14, 2014, 04:10:45 PM »

do BOTH outputs work simultaniously or as soon as you plug one headphone in the other output is disabled ?

Sorry, didn't try that. Only tested one output at a time. Someone else might chime in about that.
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Solderdude

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Re: Bakoon HPA-01
« Reply #52 on: October 14, 2014, 05:09:46 PM »

The Satri circuit will be very similar to this (current conveyor)


Y and X are inputs (inverting and non-inverting low Z as they are coupled in the emitters)
Z+ and Z- are current outputs (differential)

Audio GD also uses these circuits:


a voltage output Satri based amp (diamond output buffer)


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Anaxilus

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Re: Bakoon HPA-01
« Reply #53 on: October 14, 2014, 05:42:36 PM »

Maybe one of you guys should check out the Current Conveyor amp on diyaudio? Seems to be a awesome design for a voltage mode satri-style amp. I'm surprised it does not benefit orthos given ortho's relatively flat impedance.

http://www.diyaudio.com/forums/analog-line-level/223835-current-conveyor-voltage-amplifier.html

Mr. Anax only tested the....HE-5 and PM2 unless I'm mistaken.


You are correct sir.
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Armaegis

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Re: Bakoon HPA-01
« Reply #54 on: October 14, 2014, 07:15:41 PM »

Is the Satri stuff similar at all to the Krell CAST and Audio-gd ACCS?

(having done very little reading on the subject matter... I just know (think?) they hold everything in the current domain)
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Re: Bakoon HPA-01
« Reply #55 on: October 14, 2014, 08:38:32 PM »

Yep, very similar.
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Armaegis

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Re: Bakoon HPA-01
« Reply #56 on: October 15, 2014, 04:58:25 AM »

Would you be able to provide some non-salesbabble explanation for why those would be "better" than standard voltage driven connections?
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Do you think there may be an acoustic leak from the jack hole? ~Tyll Hertsens

Not sure if I like stuffing one hole or both holes. Tending toward one hole since both holes seems kinda ghey ~Purrin

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Re: Bakoon HPA-01
« Reply #57 on: October 15, 2014, 05:15:14 AM »

No, not really.

Most of the claims they have in their http://www.bakoonproducts.com/technology/satri-advantages/ seem a bit far fetched with a hint of truth in it.
Headphones and speakers are designed to be voltage driven.

As the amp has no damping factor those that care about this (think it is relevant which I don't) should forget about this topology unless it is voltage out.

THE SIMPLEST CIRCUIT = PERFECTLY LINEAR BEHAVIOR
It may have nice linear behaviour for a non feedback design but only in the current domain so for orthos there will be low (electrical) distortion and flat FR.

ZERO NEGATIVE FEEDBACK = NO DISTORTION
Nonsense....

NO SLEW RATE = NO INPUT AND OUTPUT DELAY
of course it has a slew rate but in A/us instead of V/us the thing is BW limited.
There is some delay (physics, propagation speed etc) but it is very small, not smaller than other designs having the same bandwidth.

NO INPUT SIGNAL LIMIT = THE WIDEST FREQUENCY RANGE
It should be noted that with a crisong impedance of most headphones (it is an inductor) the output voltage will rise.
So when using your NOS DAC those spikes you didn't want are amplified like crazy.
Above a certain frequency the output level drops again because of cable capacitance kicking in.
ONLY nice looking squarewaves when driven in a resistance which headphones are not.
The no input signal limit is true for every design.
If you want you can feed 100MHz in ievery amp, it just won't come out as 'loud' as a 1kHz signal though.
What they mean is that it doesn't have an input filter low pass filter which is recommended for most feedback based circuits.

FIXED OPERATING POINT = NOT AFFECTED BY OUTSIDE FACTORS
Willing to bet that not all transistors are created equal and there is some thermal drift.
How audible this is remains to be seen though.
There are lots of other designs that are pretty resistant against voltage rail changes and temperature (stable enough to not change properties)
I do wonder how it handles cell phone signals (it may well be affected by this outside factor as it is filled with PN crossings (they can act as detectors for HF signals)

As mentioned the idea isn't new and certainly not ground breaking and not exclusive for Bakoon.
They may have a slightly different implementation as the posted circuits but the essence remains the same.
Novelty thing ... but that was said about a lot of things in the past (internet for instance)  ::)
« Last Edit: October 15, 2014, 09:44:13 AM by Solderdude »
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Armaegis

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Re: Bakoon HPA-01
« Reply #58 on: October 15, 2014, 05:26:29 AM »

Thanks. I'm pretty good for deciphering metallurgical technobabble, but the EE stuff gives me headaches.


(says the guy who goes "nah I don't need to shut off the circuit breaker, I'll just wear rubber gloves instead" when replacing worn out AC receptacles...)
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Do you think there may be an acoustic leak from the jack hole? ~Tyll Hertsens

Not sure if I like stuffing one hole or both holes. Tending toward one hole since both holes seems kinda ghey ~Purrin

MattTCG

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Re: Bakoon HPA-01
« Reply #59 on: October 15, 2014, 11:38:01 AM »

I wanted to offer a few thoughts on how the amp actually sounds, although I do appreciate all scientific information (best nap I've ever had). I tried the hd600, hd800 and he560. IMO the best pairing out of the group was the planar mag, followed by the hd800 and then the hd600 (all using current mode).

The he560 was effortless and was able to bring out the best in this hp. No part of the spectrum seemed exaggerated and the amp seemed to let the hp do what it was intended to.

The hd800 was a much more dramatic experience. We all know that the hd800 can be the Chameleon of hp's depending on the upstream gear, but I honestly had no idea that the 800 could change this much. The treble was certainly somewhat rolled off, mids about the same and the bass became almost explosive. On bass heavy material it was nearly too much sub bass. But with acoustic, jazz and singer song writer stuff, I actually enjoyed it. I only had about an hours audition between all three hp, so I'd need more time to be comfortable with what I was hearing.

The hd600 sounded good but not great. I go to the hd600 for tone mostly. And the Valhalla 2 seemed to be able to achieve the tone I was looking for better. The Bakoon was still enjoyable with the 600 though. I did not have time to listen with voltage mode.

I might have another opportunity to pick up the Bakoon and have a longer evaluation period. So hopefully more to come.
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