[rlw6534]

I think a key issue is that the "Gryphon" is mainly a copy & paste merge of xDSD & xCAN I designed.

When originally designed the xDSD was meant as replacement for the 199 USD nano iDSD black label. As it had more inputs (SPDIF, Bluetooth) it was targeted at ~ 250 USD.

The xCAN started life as replacement of the 129 USD iCAN nano and the BT system was supposed to be optional, with perhaps ~ 150 USD target, on the request by S&M. It was to have a classic potentiometer as volume control, which pretty much rules out a true balanced circuit and as a fairly cheap product that's how it was designed.

It kind of jumped to the x series casework and other details because then S&M decided it would not possible to sell a balanced iCAN nano in the nano casework.

Also, the designs are quite old now, released in 2018 and designed quite a bit earlier. As in many ways the xDSD and xCAN ended up competing against each other, so it was clear that the next generation would merge the two devices conceptually. I left iFi before any real work was started on this.

Originally the idea was to get both the xDSD V2 AND a replacement for the iDSD micro using all the improvements (like volume control) and making them portable / transportable counterpart to dedicated "Desktop" units which, for the xDSD broadly came with the iDSD Neo and the parallel unit to iDSD micro (and signature, finale and diablo). What ifi offered me to do the job as external design studio was a joke, so I declined their offer. As a result there were no really new products in the micro category only warmed up leftovers and so far no desktop "micro" range.

The "Gryphon" appears "designed" by a copy/paste merge of xDSD & xCAN at the chinese factory, without taking advantage of the opportunity to go for a fully balanced circuit (the cost impact would have been minimal) and carrying a lot of circuitry in the audio path that could have been removed (so yes, there are more daisy chained active stages than really needed, which is never a good thing). It also did not get the dual loop headphone amplifier I tested out on the "Neo" based on what I see on the PCB, which would have lowered noise and distortion.

Lastly, yes, many other commercial "balanced" Headphone amplifiers actually turn the incoming signal to sigle ended and use the same system as I did in the xCAN and Diablo where the balanced out is created by inverting the SE Amplifier output, including some very pricey and "High End" ones. But yes, I consider a less than optimum approach to designing the audio path.

Thor

It's a shame the the word "balanced" can have multiple meanings in the audio world... In my case it just leads to a confused customer as most products use "balanced" as a selling point, implying that it's better somehow (even for IEMs)...

 

[Thorsten Loesch]

ie match does impact the sound in a negative way - it somehow compresses dynamics

As it is just a pair of high quality resistors, I somehow doubt this. It may change the frequency response, but it cannot really alter objective or perceived dynamics.

I really don't want to see it in high end audiophile devices anymore - sure it can help with the noise, but I don't want to pay with sound quality for that. I'm staying away from IFI for a while until they do some innovation and restructuring of their topology. It feels all their newest products are rehashes of old tech, and IEmatch needs to go for better silent circuits (preferably class A).

Before I left iFi I was working on such topologies and had expected to have see them long deployed generally in iFi products. Alas, things went a different way.

There is also no need for so much power, i'd much rather 250mw of silent muscular class A over hissy wimpy opamp based 500mw - it makes my headphones loud, great, but they sound strained and grainy.

The problem is if the marketing department lacks the skill to sell based on quality and can only market numbers (like DSD512 or "big output power" the designer(s) are pressured to maximise these numbers, even they are pointless and perhaps even cause a drop in actual audio quality under more realistic use cases.

That said "250mw of silent muscular class A over hissy wimpy opamp based 500mw" is a loaded statement.

Class A is NOT "muscular", but highly inefficient.

To make a Headphone Amp that is sufficient for a HD800 and gives 115dB SPL (needs ~ 4V minimum) and that is class A at rated 4V output into 16 Ohm (that would give 1,000mW incidentally) we need ~ +/-9V Power supplies and ~ 175mA quiescent current, or 3.15W per channel. If we have a constant power draw of 6.3 VA for the HP amp alone, a 25Wh battery (e.g. 7,000mAH @ 3.7V) would be needed for 4 Hours playback time.

It's fine for desktop products using off-mains power supplies (well, not according to Saint Greta of climate change who observes that the world suffers a climate emergency and that our stocks of Polar Bears are running extremely low), but challenging for anything running off batteries.

And "hissy wimpy op-amp based" - well it doesn't have to be hissy and it can easily provide a lot of power, so not wimpy.

Even using the parts used in the xDSD (and gryphon) it is actually possible to make a fairly quiet Amplifier, around 1.4uV noise should be possible in BAL, which is 117dB below 1V and would be quiet on most IEM's AND allow around 1 Watt into 16 Ohm while not needing huge batteries. As remarked, I was working on that back in 2018.

Thor

 

[Thorsten Loesch]

It's a shame the the word "balanced" can have multiple meanings in the audio world... In my case it just leads to a confused customer as most products use "balanced" as a selling point, implying that it's better somehow (even for IEMs)...

I think it is a shame that Audio products are marketed on numbers and features, which are not in any way relatable to what we hear. Ideally we would have numbers that are meaningful and actually tell the customer about sound quality and features should be useful in practice.

Realistically, IEM's have so different requirements from the source compared to say planar or dynamic full size headphones, they need dedicated designs focused on low noise etc. that would be unable to drive most full sized headphones.

That makes making such a "headphone amp" a hard sell to sales and marketing people. On the other hand, making a Balanced Amp that can drive big "top of the line" headphones well is an easy sell. After all, "balanced" must be better than "unbalanced". I mean who would say "I prefer unbalanced sound to balanced sound!"?

Yet for IEM's unbalanced is generally better, as it always has lower noise and distortion, all else being equal. If you have budget for two amplifiers, run them in parallel will give 3dB lower noise in an iEM than a single one, 6dB lower noise than these two amp's used in an optimum balanced design and 12dB lower than a SE in - Bal out Amp. And if we double Amp's up again, another 3dB less noise.

Thor

 

[Ferdinando1968]

To make a Headphone Amp that is sufficient for a HD800 and gives 115dB SPL (needs ~ 4V minimum) and that is class A at rated 4V output into 16 Ohm (that would give 1,000mW incidentally) we need ~ +/-9V Power supplies and ~ 175mA quiescent current, or 3.15W per channel. If we have a constant power draw of 6.3 VA for the HP amp alone, a 25Wh battery (e.g. 7,000mAH @ 3.7V) would be needed for 4 Hours playback time.

Thor

Sorry Thor,
I would like to take advantage of your expertise.
Could you explain these counts to me?

I understand that 4V into 16ohm provides 1W.
But why do I have to have +/- 9 V to obtain 4V in class A?
And why 175mA quiescent current ?

 

[Thorsten Loesch]

I understand that 4V into 16ohm provides 1W.
But why do I have to have +/- 9 V to obtain 4V in class A?
And why 175mA quiescent current ?

4V RMS = 5.6V Peak.

Add in losses for transistor saturation and resistors in the circuit and leave a little headroom, as getting close to limits rapidly degrades performance.

So this accounts for 9V (I guess 8V might be ok, needs testing).

Why 175mA? To support 5.6V into 16 Ohm we need 350mA. In a push-pull amplifier biased into class A the peak output current in Class A is 2 X Quiescent current, so 175mA quiescent current and +/- 9V (appx.) make an Amplifier that will deliver enough output to drive a HD800 or similar headphone and is class A into 16 Ohm.

We can of course compromise the design. Or we change the goalposts.

We can insist for example on 250mW Class A at 16 Ohm and also 250mW into 600 Ohm in Class A. This needs ~90mA quiescent current and ~ +/-20V Powersupply. This is an amplifier that is Class A for most realistic situations and delivers the maximum class A power into ~95 Ohm, but with suitably designed power supplies and protection circuits it would deliver 9 Watt into 16 Ohm.

Another alternative would be to use the +/-20V and change the output stage from being mainly Class A into what D Self calls "optimum Class B" and the rest of the world calls Class AB, if we use 1 Ohm emitter resistors in class AB the optimum quiescent current is 26mA for bipolar outputs. This allows only 37mA RMS in Class A, anything above is Class AB. Now we only have 22mW in Class A into 16 Ohm (likely fine for any IEM to make your ears bleed) and gives full 12V in class into ~ 300 Ohm.

So this too is likely fine in practice, to give sensible listening levels on any real headphone. The TI TPA6120 Op-Amp is pretty much a Class AB Amp according to the above formula, but it can only give 10V, not 12V RMS output. Running two channels in parallel will allow 1.4A peak current into low impedances. It is probably desirable to lower the power supply voltage when driving low impedances, so for example with +/-6V the TPA6120 supports 3V RMS into 3 Ohm.

Incidentally the TPA6120 is used in all iDSD micro derivatives (including Diablo) with a power switchable between +/-6V (Eco), +/- 9V (normal) and +/-16V (Turbo). Gain is also adjusted, I had wanted to set it so that each mode just clips with the volume at max, but S&M disliked that and asked me to crank up the gain.

Noise is a very different story. If we use a modern TI OP-Amp (say OPA1656) we have less than 1uV noise from the "wimpy noisy op-amp", but the Volume control and feedback network contribute noise.

Let's take a 50k Volume control (potentiometer or NJW1159) with a 2V signal from the DAC Output and our Op-Amp (with a TPA6120 with two channels paralleled inside the feedback loop) and set the volume. We make the feedback network a wire, so there is no gain and no noise is added. The volume control adds 2uV noise (from the resistances). Due to the way random noise adds (rootsumsquare) output noise is ~ 2.23uV with a signal level of 1V. That is under "ideal" conditions, it cannot get better.

So this is about the lowest noise Amp we can make using OPA1656 and TPA6120 with an analogue volume control. For a 120dB/1V IEM this leaves a background noise of around 7dB nominal and a SNR of 113dB, which incidentally roughly matches the SNR from the DAC Output, for 110dB SNR at 0dBFS input and 1V output (and should be fine).

If the Headphone Amp has a balanced output created by inversion of the signal, SNR would be degraded by ~ 7dB for the balanced output delivering 1V and around 1dB if delivering 2V (balanced only is similar in SNR if the level is doubleds).

Had the gryphon received the OPA1654 + MAX97220 double loop headphone amp from later product designs, SNR should have been very similar for iEM's to our example above. Instead the MAX97220 is used outside the feedback loop, so noise is much higher, at around 7.5uV SE and ~ 20uV in BAL, giving ~ 102dB SNR on SE and ~ 94dB on BAL for 1V output, in low gain.

Thor

 

[funkyphonicsmonkey]

Has anyone got a good recommendation for a good amplifier to connect the gryphon to in order to drive passive standmounts? Nothing too expensive, something like a chi-fi Amazon thing is fine.

 

[Mr BubbaHyde]

Has anyone got a good recommendation for a good amplifier to connect the gryphon to in order to drive passive standmounts? Nothing too expensive, something like a chi-fi Amazon thing is fine.

I have been hearing some good things about this Fosi, below is a link to a positive review from this product

Perhaps this may work for you...



Cheers!!

 

[Thorsten Loesch]

Has anyone got a good recommendation for a good amplifier to connect the gryphon to in order to drive passive standmounts? Nothing too expensive, something like a chi-fi Amazon thing is fine.

TPA3255 based, breeze audio. Like this:

https://www.aliexpress.com/i/2255800784263067.html

I have this one here, it's acceptable and upgradable. Even the BT section is not that bad.

They also have a 2.1 version if you add a passive subwoofer (maybe DIY?).

Thor

 

[Mad Lust Envy]

Hi,

Mostly happy new owner of the Gryphon.

One major thing though. The screen rotation option.

Can we please separate that and volume knob rotation?

I like holding the Gryphon on my left hand with the volume knob being on the right side, and would expect like the Go Blu, rotating clock-wise would raise volume. This IS the case if the screen is upside down if you like the knob to be on the right side.

But if I change the screen rotation to be right side up (as in facing me properly with the volume knob on the right (LIKE the Go Blu), volume rotation CHANGES the other way. So if I rotate the volume clockwise, the volume goes DOWN instead of up.

So I either have to get used to a reversed knob (as in clockwise lowering volume), or have the screen upside down.

A thing a simple fix if possible is adding an option for volume rotation, and untethering it from screen rotation.

Just a minor gripe. Love the Gryphon. Got it after I lost my Go Blu. Was a bit too small for someone good at losing small things.

 

[funkyphonicsmonkey]

Hi all,

Was there an update to allow to use in battery protected desktop mode? Sorry, there are 248 pages!

 

[jjazzy]

Hi,

Mostly happy new owner of the Gryphon.

One major thing though. The screen rotation option.

Can we please separate that and volume knob rotation?

I like holding the Gryphon on my left hand with the volume knob being on the right side, and would expect like the Go Blu, rotating clock-wise would raise volume. This IS the case if the screen is upside down if you like the knob to be on the right side.

But if I change the screen rotation to be right side up (as in facing me properly with the volume knob on the right (LIKE the Go Blu), volume rotation CHANGES the other way. So if I rotate the volume clockwise, the volume goes DOWN instead of up.

So I either have to get used to a reversed knob (as in clockwise lowering volume), or have the screen upside down.

A thing a simple fix if possible is adding an option for volume rotation, and untethering it from screen rotation.

Just a minor gripe. Love the Gryphon. Got it after I lost my Go Blu. Was a bit too small for someone good at losing small things.

Had to sell mine… got annoyed by the noise with more than one sensitive IEM’s.

But it is a nice dac/amp but not for sensitive iem’s, and IEMatch is not the solution for that, it kills dynamics for those IEM’s

If they would build a silent one, I would buy one again.

 

[HighAlt]

This tech stuff is going over my head. Will this work with Senn HD-660 S2? I understand there won’t be a fully balanced signal, etc. - but power-wise, will it suffice for a portable amp?

 

[povidlo]

This tech stuff is going over my head. Will this work with Senn HD-660 S2? I understand there won’t be a fully balanced signal, etc. - but power-wise, will it suffice for a portable amp?

Don't worry, gryphon is very powerful for portable and balanced out sounds great. Drives my hd 6xx well, no problem.

 

[gikigill]

This tech stuff is going over my head. Will this work with Senn HD-660 S2? I understand there won’t be a fully balanced signal, etc. - but power-wise, will it suffice for a portable amp?

I'll be able to confirm in a few days as the 660 S2 is on the way. Already got the 660 but the S2 is a different beast.

 

[BlackD]

Gryphon drive my audeze lcd-2c without any problems. I even not feel difference when connect it to more powerful amplifiers.