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Review and Measurements of Apogee Groove DAC and Amp

carlo

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Thanks, I'm from Italy. I was aiming at 300 ohms as the 20 ohms impedance of the Groove may ask for medium to high impedance Headphones. But I am no expert at all, just report what I've read...only I wonder if higher impedance means also has to drive. Anyway it seems that the Groove could handle this. Bought the Groove in super-mint conditions for 50 euros...
 
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PuX

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Somebody suggested me Sennheiser HD660 or Beyerdynamic 880pro, being both models at 300ohm.
neither are 300Ohm.

HD660 are 150Ohm.

Beyerdynamic DT880 has multiple editions, including 250Ohm and 600Ohm. I have both and prefer the PRO version in terms of comfort vs one of the premium editions. 600Ohm is supposed to sound a little bit better but on most amps 250Ohm is an easier load.
 

carlo

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@Veri @PuX. Thanks for your advice.
Anyway in relation to the 20 ohm impedance of my Apogee dac I’ll need to opt for a headphone not lower than 250 ohms, right? Even 600 would be fine or probably too much to drive? I’ not talking about sound quality but just with regards to matching. Just to know if there is a limit below which I must not go.
 

Veri

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@Veri @PuX. Thanks for your advice.
Anyway in relation to the 20 ohm impedance of my Apogee dac I’ll need to opt for a headphone not lower than 250 ohms, right? Even 600 would be fine or probably too much to drive?
The 'ideal' ratio is 1:8 or better. So 20 ohm output matches best with 160ohm headphones or higher. ~1ohm output would match best with ~8ohm headphones or higher (so basically anything).

So yes the 20 ohm limits your choices a little but anything >160ohm should do well. Something at 300 like the HD650 would be a great match.
More info here: http://nwavguy.blogspot.com/2011/02/headphone-amp-impedance.html
 

carlo

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I recently visited the Drop ( formerly Massdrop) site and I've noticed that some of the products are shipping to Italy ( where I live), some are not.
Sennheiser HD6xx are not, while I've seen a good deal on Hifiman 4xx which can be shipped to Italy. Costs are not so much, though I have to figure out taxes for import.
Anyway my question is about impedance which is 35 ohms, so absolutely not a good mach with my Apogee Groove dac/amp, but have read somewhere that damping factor does not have any influence in planar headphones (like this 4xx). Ask you experts if this is true. Beside this I also wonder if the behavior of Apogee, which has been very well tested here, would be power-like adequate due to sensitivity 93db and Groove's power out at low impedance which - if I understand- is not that great. Too many doubts maybe about this Headphones and probably better get a Senny from Europe, but the price is inviting and it seems 4xx are a good product. Thank you so much for your advice.
 

Veri

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I recently visited the Drop ( formerly Massdrop) site and I've noticed that some of the products are shipping to Italy ( where I live), some are not.
Sennheiser HD6xx are not, while I've seen a good deal on Hifiman 4xx which can be shipped to Italy. Costs are not so much, though I have to figure out taxes for import.
Anyway my question is about impedance which is 35 ohms, so absolutely not a good mach with my Apogee Groove dac/amp, but have read somewhere that damping factor does not have any influence in planar headphones (like this 4xx). Ask you experts if this is true.
The part about planars is true. Most of them don't respond to output impedance, or if they do, at least not in a significant way.
 

carlo

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Thanks @Veri, you confirm what I've read is true. Now the point is wether the Groove's power output is ok for this HE4xx or not, which at 93 db seem quite power hungry. From @amirm measurement I have assumed - as far as I can understand, but maybe easily wrong- that Grooves has poor power output at low impedances: despite 225mW claimed on the specs it delivered only 78 at 33 ohms before shutting down.
 
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Veri

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Thanks @Veri, you confirm what I've read is true. Now the point is wether the Groove's power output is ok for this HE4xx or not, which at 93 db seem quite power hungry. From @amirm measurement I have assumed - as far as I can understand, but maybe easily wrong- that Grooves has poor power output at low impedances: despite 225mW claimed on the specs it delivered only 78 at 33 ohms before shutting down.
Yeah that might not be ideal. An E1DA over 2.5mm balanced cable to your HE4xx can push a multitude of that. Not sure the Groove will be plenty.
 

Head_Unit

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How does a current drive differ from a voltage drive amp?
Yeah that is such a good question for this product, Apogee don't explain really what they mean by "Constant Current Drive™" so we have to guess a bit.
- A voltage amp ideally provides the same output voltage regardless of variations in load impedance.
- A current amp would ideally provide the same output voltage regardless of variations in load impedance. This is periodically proposed to remove a number of distortion mechanisms, the problem being the frequency response will tend to follow the impedance curve.
So although the high output of the Groove looks a good match to my 600 ohm AKGs, the current drive tends to scare me off.
 

manueljenkin

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Yeah that is such a good question for this product, Apogee don't explain really what they mean by "Constant Current Drive™" so we have to guess a bit.
- A voltage amp ideally provides the same output voltage regardless of variations in load impedance.
- A current amp would ideally provide the same output voltage regardless of variations in load impedance. This is periodically proposed to remove a number of distortion mechanisms, the problem being the frequency response will tend to follow the impedance curve.
So although the high output of the Groove looks a good match to my 600 ohm AKGs, the current drive tends to scare me off.

I've had it for a while and I can confirm that it does indeed have something special. Every headphone I plug in sounds very similar. Though I don't see the fr being affected, I can hear differences in staging (they image right at the driver). I can confirm that it does have a lot of brute with high impedance cans, and can drive even my hd425 vintage to fairly decent levels.
 

raffetazarius

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Sennheiser were bundling the Groove with the HD 660s for a while (now discontinued): https://en-us.sennheiser.com/headphones-audiophile-high-end-hd-660-s-apogee
I'm surprised Sennheiser were doing this, given the 21 ohm output impedance of the Groove combined with the 150 ohm impedance of the HD 660s. Thoughts? Going by the "1/8th rule", it seems like the Groove should only be used for 20 ohm x 8 = 160 ohm or greater headphones. Would the 10 ohm difference of the HD 660s cause much frequency response variation?

Also, can anyone tell me if the "1/8th rule" of output impedance vs. headphone impedance apply to connecting speakers also? I'm struggling to find info on what impedance a Presonus Temblor T10 without 2 x M-Audio BX8 D2s hooked up to it would be. Maybe all speakers are just a standard impedance, I'm not sure....
 

manchorov

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I have an HD660S and an Apogee Grovee and the combination is great ... Much better than other devices. Even with my Focal Elegia it sounds great ...Apogee Groove is a great product. Better than Audioquest all colors, IFI Nano Idsd BL ... and everything at this price.And I will not talk about the sterile Chinese at this price. Enjoy listening to the measurements ... :)
 
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Head_Unit

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21 ohm output impedance of the Groove
Is that in some spec sheet somewhere? If so, I wonder how it is measured. "Constant Current Drive™" implies to me that such concepts are irrelevant for this product.
- As for the 1/8 rule...eh maybe I'm too much the engineer, but I like more a rule of 80 or anyway just a few tenths of an ohm. I suppose a lot of headphone amps fail that because they can't handle for instance accidental short circuit so maybe they put some resistance in line. Both headphone and loudspeaker impedances vary tremendously from model to model, and they are NOT "8 ohm" or "4 ohm" or whatever ohm resistors except in the most vague sense.
- "Presonus Temblor T10 without 2 x M-Audio BX8 D2": those are all active, so their input impedance would be very high compared to raw speakers. BX8 "Input Impedance: 20 k ohms balanced, 10 k ohms unbalanced" and T10 not specified but probably 10k-20k ohms as well.
I'm not sure what your question is about that: you are asking what happens driving those from an Apogee Groove?
 

Makahl

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Hey, does anyone with an HD6X0 also suffer from anxiety due to how powerful the Groove is? ATM I'm using it at 10% on W10 and I fear a bit if I randomly misclick something the volume goes up to 100% and I might get permanent hearing loss.

I've been thinking of adding an iFi IEMatch or does anyone know a better/cheaper solution?
 
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threefour

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I'm wearing my Beyerdynamic DT 770 Pro 250 ohm which are plugged into my MacBook Pro M1 Max. The MacBook (officially) drives them mostly fine, but there are times when I would like it a bit louder. I bought the Groove and it did indeed give me more volume. I'm a music producer and value transparency above all, and I felt the non-Groove setup was just a bit clearer than the Groove setup, even if the Groove sounds amazing. So, I'm selling my Groove and will accept my volume levels.
 

Jimster480

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I'm wearing my Beyerdynamic DT 770 Pro 250 ohm which are plugged into my MacBook Pro M1 Max. The MacBook (officially) drives them mostly fine, but there are times when I would like it a bit louder. I bought the Groove and it did indeed give me more volume. I'm a music producer and value transparency above all, and I felt the non-Groove setup was just a bit clearer than the Groove setup, even if the Groove sounds amazing. So, I'm selling my Groove and will accept my volume levels.
Or you could get a real Amp. There is no way in hell the MacBook drives a 250ohm at any decent volume. Apple headphone jack outputs have been just okay for years... My friends 2016 MacBook pro barely drove his 80ohm DT770s to a good volume.. You must have literally 0 bass response with a 250ohm.
 

staticV3

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@Jimster480 the new Apple silicon MacBooks can output 3Vrms into high impedance loads. That's plenty loud enough for most high impedance studio headphones e.g:
-ATH-R70x: 113.5dB SPL Peak
-DT 990 Pro 250Ω: 106.5dB SPL Peak
-DT 770 Pro 250Ω: 110.5dB SPL Peak
-HD 650: 114.5dB SPL Peak
-HD 800 S: 115dB SPL Peak

You must have literally 0 bass response with a 250ohm.
Why would there be a change in frequency response?
 

elvisizer

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There is no way in hell the MacBook drives a 250ohm at any decent volume
and that's where you'd be wrong 'cause the amp and output have been updated to deal better with high impedance headphones. that happened a couple of years ago now. 2016 macs are VERY different from the current models.
 
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