Review and Measurements of Meier Corda Jazz Amp

[MRC01]

Sure, but it's just not worth being without the amp for a week or two while they replace the switch. Especially since I never use high gain anyway.

 

[Jimster480]

Maybe they should make a premium option that is $50 more with better quality everything else....

 

[Veri]

Maybe they should make a premium option that is $50 more with better quality everything else....

This should be in the works

 

[MRC01]

I agree in principle, but the switch on mine [JDS Atom] actually broke only the 2nd time I pushed it (gently), making it hard to appreciate the value.

Update: the switch isn't broken; the problem was mis-alignment of the switch's plastic nub/cover with its hole in the case. The switch nub was rubbing against the edge of the hole in the case through which it extends, creating enough friction to prevent the switch's spring from pushing the switch all the way outward. This prevented the switch's toggle reset from activating. I was able to remove and re-seat the switch's plastic nub so it doesn't rub and now the switch works. All good!

Still, this problem was caused by taking the "value" proposition just a bit too far, toward the laudable goal of maximum sound quality at the minimum price. It wouldn't happen if the JDS Atom had a metal case with more precisely aligned parts. Even if it cost a few more bucks, an upscale version of the Atom having a more precision metal case & knobs would still be an incredible value.

 

[graz_lag]

Update: the switch isn't broken; the problem was mis-alignment of the switch's plastic nub/cover with its hole in the case. The switch nub was rubbing against the edge of the hole in the case through which it extends, creating enough friction to prevent the switch's spring from pushing the switch all the way outward. This prevented the switch's toggle reset from activating. I was able to remove and re-seat the switch's plastic nub so it doesn't rub and now the switch works. All good!

Still, this problem was caused by taking the "value" proposition just a bit too far, toward the laudable goal of maximum sound quality at the minimum price. It wouldn't happen if the JDS Atom had a metal case with more precisely aligned parts. Even if it cost a few more bucks, an upscale version of the Atom having a more precision metal case & knobs would still be an incredible value.

Sure, but it is not only a matter of cost.
Sometime, companies look for different types of casing solution in order to make an item distinguishable from the competition.

 

[JediMa]

... I have this amp and to read this review and comments really made me sad and mad. It's all just true and right ... so I wonder with what I could replace it without spending too much money. Any help?

 

[MRC01]

Hmmm.... essentially the only thing "wrong" with this amp is that it has limited voltage output. Other than that, it has some positive measurements. At 50 mV (typical listening levels) its SNR is among the best amps that Amir has measured. Due to its unique design, the SNR actually gets better, not worse, as you turn down the volume. It has perfect channel balance at all volume settings. And it has < 1 ohm output impedance, not current limited, it makes 10x more power into 30 ohms than 300 ohms. Also, the crossfeed is useful with recordings having hard L-R separation.

Even though its voltage output is limited to about 3.6 V, this drives Sennheiser HD-600s to about 116 dB SPL and Audeze LCD-2 to 120 dB SPL. Generally speaking, it's enough to drive typical headphones loud enough to be uncomfortable and cause hearing damage.

I would say if you already own it, and it has enough power for you (you aren't turning up the volume past 2:00), then why replace it?

 

[JediMa]

Hmmm.... essentially the only thing "wrong" with this amp is that it has limited voltage output. Other than that, it has some positive measurements. At 50 mV (typical listening levels) its SNR is among the best amps that Amir has measured. Due to its unique design, the SNR actually gets better, not worse, as you turn down the volume. It has perfect channel balance at all volume settings. And it has < 1 ohm output impedance, not current limited, it makes 10x more power into 30 ohms than 300 ohms. Also, the crossfeed is useful with recordings having hard L-R separation.

Even though its voltage output is limited to about 3.6 V, this drives Sennheiser HD-600s to about 116 dB SPL and Audeze LCD-2 to 120 dB SPL. Generally speaking, it's enough to drive typical headphones loud enough to be uncomfortable and cause hearing damage.

I would say if you already own it, and it has enough power for you (you aren't turning up the volume past 2:00), then why replace it?

You have a point here.. and I thought that was fine but not so powerful, it happened few times to go to 3:00 too. To answer to your really right answer.. well I posted here about a complete different matter, a DAC https://www.audiosciencereview.com/forum/index.php?threads/dac-upgrade-help.14703/#post-456103 but the first reply lead me to this post and what I 've read disappointed me.
So it's a relief to read what you just wrote here above, so I think i'm back to my original question about a DAC

 

[JediMa]

I'm so far from all your knowledge and skills (i'm sincerely impressed by the level of this forum... wow) so I will only share my humble feedback as owner and listener of this amp.
It's not so powerful, that's a fact but It's also true that with none of my headphones I've been able to go to 3 but also hardly to 2 (the evil zone of noise). It's very essential and clean, talking bout design, it's true it won't hit the eye but it's subtle and looks solid which I like. The sound is very neutral and what is very nice and can't be not noticed is how nicely works the crossfade circuit.
It's been my first "serious" amp when I started to enjoy music with good headphones, not a cheap start but at the times sounded very good.
What I can tell and you also noticed here, it's that Jan is a very kind and willing to help person and it's also in the package of what you get with the amp, can sound old fashioned, but to some people like me, it's nice and valuable.
So in the end I will go on to use it but I will add another solid state amp a JDS Atom to have a newer and powerful alternative.

 

[donunus]

Sorry if I missed it but is this the latest FF version of the Jazz?

 

[MRC01]

As I recall, both tested were the non-FF version (at least mine was). From what I know about FF, it might make a small difference in the distortion or noise measurements (less in mids & treble, more in bass). And FF substantially increases the available output power under most conditions.

To explain: FF is Meier's "frequency adaptive feedback". It is a kind pre-emphasis, similar in concept to the RIAA curve for LPs, or the optional pre-emphasis in the redbook CD standard. Imagine an EQ that attenuates bass and levels off flat in the mids/treble. It is applied to the analog input, before the amp's gain-feedback loop. Then the reverse EQ is applied after the gain-feedback loop, before the amp outputs. The idea is to emphasize the most hearing-sensitive frequencies in the amp's gain-feedback loop, while retaining flat overall frequency response. Since the amp's gain-feedback loop determines noise & distortion, it's a way to psycho-acoustically shape the noise-distortion profile. At least that is how I understand the idea, from Meier's description.

Another effect of FF is that it partially mitigates the voltage clipping that limits the Jazz max output level, enabling it to play louder before that distortion kicks in. As I understand from the detailed discussion here (in which Meier participated), this clipping is a voltage limitation of the resistors used in the gain-feedback loop. Most of the overall amplitude of music is in the bass, so reducing bass reduces the overall voltage of the musical signal. The reverse EQ is applied after the gain-feedback loop, so the gain-feedback loop resistors never see the full scale signal, which means it doesn't clip. So, how much more voltage & power the FF Jazz can produce, depends on the frequency spectrum of the music you listen to. Mid-treble frequencies above the FF curve will not be affected, they will have the same max output level as before. Lower frequencies will have a higher max output level - how much higher depends on the shape of the FF curve. Meier quotes 3.7 V max for the non-FF Jazz (across all frequencies), which is about what Amir measured. And 15 V at 200 Hz, so about 12 dB louder in the bass. That difference gives some idea of the shape of FF curve: it's down 12 dB at 200 Hz.

 

[rocksteady]

I think JDS are missing a trick, they should put the Atom internals in a fancy metal box ballasted down to weigh a few kilos and charge $$$$$$$$$$$$$'s for it. Add wooden side panels, champagne gold finish and stick a couple of VU meters on the front and it'd be just tip top. Never underestimate the sonic benefits of champagne gold finish, wooden side panels and VU meters, some will try and tell you it doesn't make any audible difference but to the true golden eared audiophiles among us these things definitely add more pace and rhythm, lifting a veil and move you two rows forward.