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Questyle CMA800 Current Mode amp
Aug 3, 2013 at 6:04 PM Post #3 of 757
on eBay its $1,999
 
I wonder how their design differs from the Bakoon HPA-21 which is also a "current amp".
see http://www.bakoonproducts.com/technology/satri-circuit/
 
Aug 4, 2013 at 12:11 AM Post #4 of 757
The SATRI circuit is a current gain stage. What is being talked about with these headphone amps is the output to the headphones themselves being in the current domain. What Bakoon, Krell, Audio-gd and others do in most amps is have the amplification, and signal transmission between components entirely in the current domain instead of the voltage domain until the last stage before the headphones or speakers where a I/V converter is used. As far as I know, current-output headphone amps can only be used with headphones that have a completely flat impedance curve, such as orthos.
 
Aug 4, 2013 at 2:53 AM Post #5 of 757
Quote:
currawong said:
The SATRI circuit is a current gain stage. What is being talked about with these headphone amps is the output to the headphones themselves being in the current domain. What Bakoon, Krell, Audio-gd and others do in most amps is have the amplification, and signal transmission between components entirely in the current domain instead of the voltage domain until the last stage before the headphones or speakers where a I/V converter is used. As far as I know, current-output headphone amps can only be used with headphones that have a completely flat impedance curve, such as orthos.
Click to expand...

 
The HD800 has a very fluctuating impedance curve, but the HPA-21 was still the best solid-state amp I've heard with it. While the pairing with LCD-3 was very good too, I felt the HPA-21 performed better with HD800.
 
Aug 7, 2013 at 7:26 PM Post #6 of 757
Quote:
currawong said:
The SATRI circuit is a current gain stage. What is being talked about with these headphone amps is the output to the headphones themselves being in the current domain. What Bakoon, Krell, Audio-gd and others do in most amps is have the amplification, and signal transmission between components entirely in the current domain instead of the voltage domain until the last stage before the headphones or speakers where a I/V converter is used. As far as I know, current-output headphone amps can only be used with headphones that have a completely flat impedance curve, such as orthos.
Click to expand...

 
According to the Questyle website product discussion, the amplification is done in the current domain, via their "Input Buffer, Current Transmitter, Trans-impedance Amplifier and Output Buffer" in a "TransLinear(TL) loop circuit".
 
My HPA-21 seems to handle both my TH900 and LCD-2 with almost equal aplomb.
 
Aug 16, 2013 at 2:03 PM Post #7 of 757
I've got one of these on the way right now. I'll be covering it at InnerFidelity, and will definitely get to the bottom of this whole "current mode" business. Language barriers will slow me down but I can usually get past that given enough patience (on their end and mine).

I think the external design is very reminiscent of the Luxman P200. Not calling it a copy at all, just a similar visual theme.
 
Aug 19, 2013 at 7:46 PM Post #8 of 757
I thought about getting one, but the marketing fellow there seems to think that the CMA800 is only optimized towards the HD800 and similar high impedance headphones.  Kept trying to steer me to the cheaper CMA600 model with the appropriate output module for my lower impedance HP suite (T5p, TH900, LCD-2).  So I'm not sure how flexible the CMA800 is at this point...
 
Trying to talk him into a factory mod (1 low gain HP outlet + higher gain (e.g. HD800) HP outlet), assuming that they're equivalent now.   
 
Aug 21, 2013 at 9:02 AM Post #9 of 757
Quote:
jacal01 said:
I thought about getting one, but the marketing fellow there seems to think that the CMA800 is only optimized towards the HD800 and similar high impedance headphones.  Kept trying to steer me to the cheaper CMA600 model with the appropriate output module for my lower impedance HP suite (T5p, TH900, LCD-2).  So I'm not sure how flexible the CMA800 is at this point...
 
Trying to talk him into a factory mod (1 low gain HP outlet + higher gain (e.g. HD800) HP outlet), assuming that they're equivalent now.   
Click to expand...

 
Thanks for the info. So far they mentioned to me the special synergy with HD800, but also recommend it for a wide variety of different cans. So perhaps a disconnect between marketing and engineering. We'll see. 
 
Aug 21, 2013 at 11:42 AM Post #10 of 757
I may just pop for one, anyway.  Questyle offered me attractive pricing as factory direct.
 
However, what time frame will you be reviewing the CMA800?  I assume that you'll also be reviewing it with some low impedance cans.
 
One thing is confusing, in that I was under the impression as a current driven HP output (not gain), that impedance matching was of little, or not as much, concern.  Do you think that they might have converted it to a voltage controlled output at the end, for whatever reason?  Is there any way you can get an answer to that via your contact?  
 
Aug 21, 2013 at 11:50 AM Post #11 of 757
Quote:
jacal01 said:
I may just pop for one, anyway.  Questyle offered me attractive pricing as factory direct.
 
However, what time frame will you be reviewing the CMA800?  I assume that you'll also be reviewing it with some low impedance cans. 
Click to expand...

 
Looks like it initially listed at $2K but now I see it at $1499 with free shipping from a reputable seller. So that's a definite improvement. Don't care how good it is, cheaper is always appreciated.
 
I'll be reviewing it with lots of headphones - custom IEMs, LCD-2, HE-500, Thunderpants, HD800, and a bunch more. Will definitely investigate the low impedance/high impedance results. But it will be a few months before I have a final review - I don't even have the thing here yet to start listening. 
 
Aug 21, 2013 at 11:55 AM Post #12 of 757
That's their retail price.  A better deal can be had because of a lack of US distributor/dealer. 
 
Sooo..., you managed to talk me into it, you silver tongued devil, you. Several months wait is like anathema to an instant gratification sort like myself.   Who knows where or what I'll be in a few months.  Altho I believe I'll hold off on any personal review of my own until after your Inner Fidelity report.  Don't want to prejudice you...
wink.gif
   Besides, I learned my lesson from the high bias Class A mafia types that squatted on the HPA-21 thread and poopooed everything non bona fide.
 
Sep 5, 2013 at 12:37 PM Post #13 of 757
songmic said:
   
The HD800 has a very fluctuating impedance curve, but the HPA-21 was still the best solid-state amp I've heard with it. While the pairing with LCD-3 was very good too, I felt the HPA-21 performed better with HD800.
Click to expand...

 
I see what you mean about the HD800s and the HPA-21...
 
Sep 17, 2013 at 1:18 AM Post #14 of 757
Has anyone tried this amplifier yet? I have just purchased one, as I wanted to try a current gain amplifier, but couldn't afford the Bakoon. Anyway, it arrived yesterday and is as dead as a dodo.  I bought it from the Ebay site listed above.
 
I have a bad feeling I now have a long uphill battle....
 
Sep 17, 2013 at 2:46 AM Post #15 of 757
Myself and at least one other headfier have the CMA800, for a few weeks now. Sorry to hear about your troubles - I thought the packaging was quite good, better than most, but maybe still not enough in your case. The good news - the eBay seller linked above, and Questyle themselves, both seem very responsive from my interactions. I think you should be in good shape.
 
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