• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

The relevance of measurements to audible quality of sound

solderdude

Grand Contributor
Joined
Jul 21, 2018
Messages
15,891
Likes
35,912
Location
The Neitherlands
only the inline version (needs an amplifier) is commercially available but not through me. G1217 only.
I don't think there is anyone else making this (all analog) but there is plenty of this in digital and software these days.

I only build up a prototype to make pics and a manual but that's it.
 

andreasmaaan

Master Contributor
Forum Donor
Joined
Jun 19, 2018
Messages
6,652
Likes
9,399
This looks interesting, but I cannot build this. Can I buy something like it anywhere?

Magnum Innominandum

I may have missed it somewhere, but I’m not sure why you wanted to use an analogue EQ rather than something in software?
 

oivavoi

Major Contributor
Forum Donor
Joined
Jan 12, 2017
Messages
1,721
Likes
1,934
Location
Oslo, Norway
I may have missed it somewhere, but I’m not sure why you wanted to use an analogue EQ rather than something in software?

The beauty of a simple analog circuit is the simplicity. No need for complications, devices which can break down, etc. Besides, adding a dedicated DSP box adds expense. The minimum needed would be a miniDSP box, I guess?
 

andreasmaaan

Master Contributor
Forum Donor
Joined
Jun 19, 2018
Messages
6,652
Likes
9,399
The beauty of a simple analog circuit is the simplicity. No need for complications, devices which can break down, etc. Besides, adding a dedicated DSP box adds expense. The minimum needed would be a miniDSP box, I guess?

Ah yes, totally with you. I thought @Magnum Innominandum had mentioned he was using software EQ originally. Wasn’t trying to suggest he should get an extra digital device.
 
OP
Magnum Innominandum
Joined
Oct 11, 2018
Messages
27
Likes
26
Location
Outer Darkness
I may have missed it somewhere, but I’m not sure why you wanted to use an analogue EQ rather than something in software?

In software an EQ strictly speaking cannot boost. If you boost a frequency above 0dB gain AND have a full scale signal the result is clipping.

So if we boost xx dB we must reduce the overall gain before the EQ in software as well. This then can lead to issues with SNR, if I boost 18dB based on the measurements an targets cited we would loose 18dB SNR/SINAD.

Hence my idea to to most of the EQ in the actual headphone cable passive. If the amplifier has enough signal available we actually lower it's noise by 18dB as in order to boost the bass 18dB we actually need to attenuate the mid-range and treble by this amount.

But it seems @solderdude disagrees with this approach and I would not really be able to do this myself.

Magnum Innominandum
 

andreasmaaan

Master Contributor
Forum Donor
Joined
Jun 19, 2018
Messages
6,652
Likes
9,399
In software an EQ strictly speaking cannot boost. If you boost a frequency above 0dB gain AND have a full scale signal the result is clipping.

So if we boost xx dB we must reduce the overall gain before the EQ in software as well. This then can lead to issues with SNR, if I boost 18dB based on the measurements an targets cited we would loose 18dB SNR/SINAD.

Hence my idea to to most of the EQ in the actual headphone cable passive. If the amplifier has enough signal available we actually lower it's noise by 18dB as in order to boost the bass 18dB we actually need to attenuate the mid-range and treble by this amount.

But it seems @solderdude disagrees with this approach and I would not really be able to do this myself.

Magnum Innominandum

I don't think in most real-world cases there's any issue with reducing the gain in the digital domain, so long as you have enough headroom. It depends on how you play your music. If you use Foobar for example, you can process everything in 32 bit, meaning you lose nothing by reducing the overall level by 18dB.

You right though, you definitely don't want to boost anything above 0dBfs.
 
OP
Magnum Innominandum
Joined
Oct 11, 2018
Messages
27
Likes
26
Location
Outer Darkness
I don't think in most real-world cases there's any issue with reducing the gain in the digital domain, so long as you have enough headroom. It depends on how you play your music. If you use Foobar for example, you can process everything in 32 bit, meaning you lose nothing by reducing the overall level by 18dB.

You right though, you definitely don't want to boost anything above 0dBfs.

If we take the 18dB boost and thus an 18dB gain reduction we shall certainly need to have an extra 18dB SNR "to give away" for the EQ. In this case we should probably need over 115dB SNR to allow this while having no reserve SNR or reserve.

Doing the job analogue with two resistors and a cap each in the headphone line on the other hand merely needs these 18dB above the 0.8V or so needed to generate 105dB peak, with > 96dB SNR.Fine tuning may be applied using digital EQ but "bulk EQ" would seem better off in the analogue domain.

That is my logic and I wonder what is so wrong with it?

Magnum Innominandum
 

Wombat

Master Contributor
Joined
Nov 5, 2017
Messages
6,722
Likes
6,459
Location
Australia
If we take the 18dB boost and thus an 18dB gain reduction we shall certainly need to have an extra 18dB SNR "to give away" for the EQ. In this case we should probably need over 115dB SNR to allow this while having no reserve SNR or reserve.

Doing the job analogue with two resistors and a cap each in the headphone line on the other hand merely needs these 18dB above the 0.8V or so needed to generate 105dB peak, with > 96dB SNR.Fine tuning may be applied using digital EQ but "bulk EQ" would seem better off in the analogue domain.

That is my logic and I wonder what is so wrong with it?

Magnum Innominandum

Do it and let us know how it went. Cheap learning.
 

andreasmaaan

Master Contributor
Forum Donor
Joined
Jun 19, 2018
Messages
6,652
Likes
9,399
If we take the 18dB boost and thus an 18dB gain reduction we shall certainly need to have an extra 18dB SNR "to give away" for the EQ. In this case we should probably need over 115dB SNR to allow this while having no reserve SNR or reserve.

Doing the job analogue with two resistors and a cap each in the headphone line on the other hand merely needs these 18dB above the 0.8V or so needed to generate 105dB peak, with > 96dB SNR.Fine tuning may be applied using digital EQ but "bulk EQ" would seem better off in the analogue domain.

That is my logic and I wonder what is so wrong with it?

Magnum Innominandum

There's nothing wrong with it except IMHO the "better off in the analogue domain" part.

If you're processing your audio at 32 bit, you have 192dB of digital dynamic range. That's more than enough to spare 18dB.

Add an additional analogue component into the chain, on the other hand, and you will lose SNR and increase distortion.
 
Last edited:

solderdude

Grand Contributor
Joined
Jul 21, 2018
Messages
15,891
Likes
35,912
Location
The Neitherlands
18dB is not needed at al. It is waaaayyyy too much.
That would make it a basshead headphone !
+7dB is more than enough otherwise the HD650 starts to sound bloated and 'fat'.

When the EQ is done digital and 32 bits is used with a 24 bit DAC you don't loose anything.

The effective dynamic range when listening to music in your livingroom (or with headphones) is about 70dB.

Assuming you would really want to boost 18dB at 20Hz and use a simple 6dB/octave filter (RC) use the filter described below.
I calculated a passive attenuator for you to try (inline with the headphone with 18dB 'boost' at 20Hz.
Total attenuation is 20dB so you need to connect it to a speaker amp output terminals to try.
Assuming you would play at max.1V then you would need a swing of 10V to reach that.

I won't publish a schematic as this would find its way and damage my 'reputation'.
The filter below is only for illustrative purposes about +18dB bass boost.

Also ... use music material that actually contains frequencies like this, say a large church organ.

1 resistor of 120 Ohm between the output + of an amplifier and the plug ring (and left channel tip) of the HD6XX One of the - connectors (assuming the amp is not balanced) to the common of the headphone plug.
+ in parallel to the headphone (so from ring to common and also one from tip to common a series circuit consisting of a 12 Ohm resistor + 47uF capacitor.

Should you want to try the 7dB boost simply change the 12 Ohm for 47 Ohm.
Tip: use a 100 Ohm potmeter and make it stepless, dial it in and measure the resistance to know how much boost is needed.

Nothing beats some good experimentation, trial and error and your own experiences.


note: if that was the only EQ it needed and it would be a simple passive solution built into an extension cord then I would have made those cords and have sold hundreds by now.:cool:
 
Last edited:

March Audio

Master Contributor
Audio Company
Joined
Mar 1, 2016
Messages
6,378
Likes
9,317
Location
Albany Western Australia
If we take the 18dB boost and thus an 18dB gain reduction we shall certainly need to have an extra 18dB SNR "to give away" for the EQ. In this case we should probably need over 115dB SNR to allow this while having no reserve SNR or reserve.

Doing the job analogue with two resistors and a cap each in the headphone line on the other hand merely needs these 18dB above the 0.8V or so needed to generate 105dB peak, with > 96dB SNR.Fine tuning may be applied using digital EQ but "bulk EQ" would seem better off in the analogue domain.

That is my logic and I wonder what is so wrong with it?

Magnum Innominandum

If the noise floor is inaudible this makes no difference. As already mentioned high bit depth processing makes it a non issue.
 

solderdude

Grand Contributor
Joined
Jul 21, 2018
Messages
15,891
Likes
35,912
Location
The Neitherlands
Thought he requested "On the go" equipment, may be wrong though ...

"It's mainly desktop, but should be easy to carry to the main office".

I read in this: desktop but not too heavy and easy to transport.
Grab a crate or box, throw the stuff + cables in there...
A one box solution may be easier but he wants to do passive EQ which is easily done in line level.
So maybe this could be one of many solutions.
It's cheap and can drive most headphones out there.
There is also a powersupply that goes with the amp though which is not shown but is extra weight... extra cables ... extra hassle.
Hmm...
 
D

Deleted member 65

Guest
"It's mainly desktop, but should be easy to carry to the main office".

I read in this: desktop but not too heavy and easy to transport.
Grab a crate or box, throw the stuff + cables in there...
A one box solution may be easier but he wants to do passive EQ which is easily done in line level.
So maybe this could be one of many solutions.
It's cheap and can drive most headphones out there.
There is also a powersupply that goes with the amp though which is not shown but is extra weight... extra cables ... extra hassle.
Hmm...

The Cavalli amp may be something for me since I just bought the Massdrop HiFiMan H4xxx a week ago unless March Audio will deliver soon ... ;-)

Not been using headphones since my youth, thought I'd give it a try so many years later. Have an Ami Musik DS5 (DAC+Amp) which I bricked a couple of years ago updating firmware, maybe should have another go at it,
 

Sal1950

Grand Contributor
The Chicago Crusher
Forum Donor
Joined
Mar 1, 2016
Messages
14,073
Likes
16,609
Location
Central Fl

amirm

Founder/Admin
Staff Member
CFO (Chief Fun Officer)
Joined
Feb 13, 2016
Messages
44,370
Likes
234,406
Location
Seattle Area
A good candidate for the @amirm lab.
That seems to be a lot of amp for the money.
Sometimes if it seems too good to be true -----------------
I have bought it but no time to review it yet.
 

Grave

Senior Member
Joined
Jun 30, 2018
Messages
382
Likes
204
I tried to equalize the Sennheiser HD 650's and the Sennheiser HD 660 S's to the Harman target headphone frequency response and there was way too much deep bass to my ears. I would suggest equalizing the bass to be flat instead because this sounds really good to me. I have both of these headphones at +7 dB at 20 Hz. Try the Harman target headphone frequency response yourself though. My Topping A30 has plenty of excess gain while using replaygain and my equalizer setting when driving either of these headphones.

Should I be using the 32 bit mode of my Topping D30? I have not been doing that.
 
Last edited:

oivavoi

Major Contributor
Forum Donor
Joined
Jan 12, 2017
Messages
1,721
Likes
1,934
Location
Oslo, Norway
I tried to equalize the Sennheiser HD 650's and the Sennheiser HD 660 S's to the Harman target headphone frequency response and there was way too much deep bass to my ears. I would suggest equalizing the bass to be flat instead because this sounds really good to me. I have both of these headphones at +7 dB at 20 Hz. Try the Harman target headphone frequency response yourself though. My Topping A30 has plenty of excess gain while using replaygain and my equalizer setting when driving either of these headphones.

Should I be using the 32 bit mode of my Topping D30? I have not been doing that.

This whole thing about target response seems a bit confused to me, TBH. Isn't the reason that listeners prefer a slightly tilted frequency response that a flat speaker that interacts with a room naturally will create an elevated response in the bass? High and low frequencies simply behave differently, so the mic will show more bass if the speaker is flat. That's how I've understood it here on this forum, at least. With headphones, there is no room, the sound hits the ear more or less directly, so the treble and bass will behave in the same way. Why should headphones be anything but flat?
 
Top Bottom