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Headphones sound harsh with Reflex-M, suggestions?

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Post Options Post Options   Thanks (1) Thanks(1)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 29 Mar 2020 at 1:27pm
Unfortunately, the answer is quite technical, and can only be solved by those who make headphone amplifiers.

All I can say is that my early attempts at headphone amplifiers (20 plus years ago) sounded harsh using a vinyl source - admittedly I always used a phono preamp of my own making - but some of them were generic designs one can find nowadays on the internet.

I would always choose a specialist manufacturer than one "who also makes" ;-)
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Post Options Post Options   Thanks (1) Thanks(1)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 29 Mar 2020 at 2:02pm
In addition to the above, and from a technical point of view, the grounding regime of a headphone amplifier can have undesirable effects depending on the headphones being used. In particular, the long-forgotten "stereo-loop distortion" which plagues op-amp headphone amplifiers which use separate chips. This causes annoying asymmetrical distortion in the input grounds, but can be cured by the designer if power amplifier techniques are used.

And, I did note that everything is alright with your speaker amp.

Most of us designers fall into the trap of looking at a headphone amp as a preamp, simply because that was the original intention of headphones (back when Noah was a lad). However, things change, and rather than headphones being high impedance, they can range from 5 ohms to 2000 ohms, for what reason, I do not know.

A high impedance headphone will not exhibit the same harshness as a low impedance headphone should there be a stereo-loop in the ground distribution.

The above might well be the reason for the mania for balanced headphone outputs, which might effect a "half cure."

One might ask, then why only with a particular phono stage? The answer to that is where the stereo grounds meet. If they meet at the output, which is incidentally wrong, then the possibility is that any stereo-loop distortion is minimised, because it is referenced to a larger signal. If the stereo grounds meet at the input, as on the Reflex and all our phono stages (the correct way), then it is referenced to a much smaller signal. Therefore the stereo-loop distortion becomes more prominent.

Your speaker amp, simply because it is much more current hungry, and grounding errors exhibit themselves more aggressively, and as such the designer understands the grounding much better, will be grounded correctly such that the source ground will be expected to be at the input of whatever that source is.



Another reason for a different phono preamp enabling lower stereo-loop distortion would be its use of tree-trunk grounding, which, for good reason, the Reflex doesn't do.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DT999 Quote  Post ReplyReply Direct Link To This Post Posted: 29 Mar 2020 at 10:30pm
Hi Graham,

firstly can I say thank you for your comprehensive reply; to me it speaks volumes when the designer and manufacturer of a product takes the time to answer questions on a forum.

Unfortunately I am not that technical when it comes to understanding electronics, however I think I get the gist of what you are saying.

Both my headphones are low impedance (Oppo PM-3 is 26 Ohms, AGK K550 is 36 Ohms); I guess being more modern closed back types they are designed to work with a portable source such as a tablet or smart phone; hence the more prominent harshness. 

I do only listen through headphones through necessity and need them to be closed back; there may be other higher impedance quality headphones that might be better suited.

However, I get the impression that it is my headphone amp that might be the issue. As this does not seem to manifest itself when using my other phono stage, I am surmising it is designed and built differently to the Reflex and where the grounds meet. 

Do you think this would be addressed with a different headphone amp? Specifically I presume you have designed your headphone amps to match and complement the design of your phono stages.

thanks again
Derek




Rega Planar 3; Ortorfon 2M Bronze > Accession MM / Thorens TD160; Denon DL-110, LP Gear The Vessel A3SV, AT-VM95ML > Reflex M > Rega Elex-R > Monitor Audio Silver 500
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Post Options Post Options   Thanks (1) Thanks(1)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 30 Mar 2020 at 2:29am
Then again, it might be none of the above, just that the Reflex M is (if you don't mind me blowing my own trumpet) a bloody superior design, showing the limitations of any vinyl front end.

I also do not buy into the whole Ortofon 2M thing. I'm sorry, but it's an OM with a fairing. It doesn't need it because it doesn't require streamlining because it doesn't travel anywhere. It is neither a stealth bomber. I have the bronze and the black and sufficient turntable stock, to have found that they are both coloured, with the black stylus being the better of the two (and rightly so given the price).

Also, didn't want to say anything yet, but developing a further headphone amplifier which exposes even more (and tackles the technical issues in my previous post), and I have to accept the limitations of what a micro vibrating fishing rod can do. I had never heard the groove contact aberrations and surface noise details of Bob's YT channel recordings to such a degree until now, and those are incredibly good cartridges he uses, but it just goes to show how good Youtube and its type of digitization can be.

To wrap up my contribution to this topic, it must be said that you will always find niggling things like this when mixing and matching amplifier circuits designed by different people. Nobody knows everything (no not even I), and to quote one much more extremely experienced industry designer: "Although solid-state amplifiers have been around for some 40 years, it would be a great mistake to assume that everything possible is known about them." (Doug Self).
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Post Options Post Options   Thanks (1) Thanks(1)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 30 Mar 2020 at 2:42am
Originally posted by DT999 DT999 wrote:

Do you think this would be addressed with a different headphone amp? Specifically I presume you have designed your headphone amps to match and complement the design of your phono stages.


Yes, but I would try and wait until I develop the next one. There is also the issue of whether I should try and "smooth the corners" or let it tell the truth. The latter is far easier and I have to take my hat off to those who have the ability to "smooth the corners". They never seem to publish the way it's done!

If you are unable to wait, I suggest you try the Solo ULDE via the loaner program.
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Post Options Post Options   Thanks (1) Thanks(1)   Quote DT999 Quote  Post ReplyReply Direct Link To This Post Posted: 30 Mar 2020 at 3:03am
Thanks again Graham

I will probably try the Solo ULDE on the loaner program to see how it goes, but may well wait until you develop your next one as well. (that will give me time to get an Accession in the mean time Big smile)
Rega Planar 3; Ortorfon 2M Bronze > Accession MM / Thorens TD160; Denon DL-110, LP Gear The Vessel A3SV, AT-VM95ML > Reflex M > Rega Elex-R > Monitor Audio Silver 500
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DT999 Quote  Post ReplyReply Direct Link To This Post Posted: 30 Mar 2020 at 4:19am
Out of interest, and in reference to Graham's comment above about higher impedance headphones potentially not exhibiting the same harshness as low impedance, can anyone tell me what is considered high impedance?

For example, would it be something like BEYERDYNAMIC DT770 PRO 250 OHM 
Rega Planar 3; Ortorfon 2M Bronze > Accession MM / Thorens TD160; Denon DL-110, LP Gear The Vessel A3SV, AT-VM95ML > Reflex M > Rega Elex-R > Monitor Audio Silver 500
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