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Post by jj2106 on May 28, 2019 9:41:38 GMT -5
I remember a thread (which I can't retrieve just now) where somebody asked whether or not to insert the supplied straps when driving headphones..
I argued against that on the basis of power calculations.
Another guy argued in the other direction on the basis of sound quality.
I now think he was right, and I was wrong.
If the 220 Ohm resistors are left in line, the amp's output impedance is in fact 220 Ohm, which is dramatically high.
The frequency response of the headphones will be adversely affected, even the 600 Ohm ones.
It is generally accepted that the amp's output impedance should be 1/8th that of the headphones at the most.
This is a damping factor of 8, which would already be considered way too low for ordinary speakers in order to get a good electrical damping.
So I revise my opinion, but in order not to risk destroying the headphones, it is probably better to stick to the highest impedance cans you can afford.
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KeithL
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Post by KeithL on May 28, 2019 9:59:12 GMT -5
You are indeed correct. "Modern thinking" is that a headphone amplifier should have a very low output impedance. (I personally prefer them that way).
However....
Vintage equipment, up through the 1960's or 1970's, virtually always derived the headphone outputs from the main outputs - through dropping resistors in the 100 - 250 Ohm range. This offers very little damping to the headphones, and can also result in a significant variation in frequency response due to the interaction between that output impedance and the impedance of the headphones.
Because of this interaction the actual frequency response, and the variation from flat, will depend on the impedance curve of the particular headphones you connect.
As such, it delivers a sort of characteristic sound, which is quite popular with some fans of vintage equipment, and some people actually purchase vintage receivers so they can get the vintage headphone outputs on them. If you look, for example, on Head-Fi, there are whole discussions dedicated to "using vintage gear to drive headphones".
(At the time, it was generally done that way to cut costs, because high quality low cost small IC amplifiers weren't yet available.)
With the resistors in-line, the A-100 will mimic this performance, with most of its pros and cons (although the main amps on the A-100 are a lot quieter).
If you install the jumpers and bypass the resistors the A-100 will sound like a modern high quality headphone amplifier. However, as a consequence of its power capabilities, it will be "dangerously powerful" for low impedance headphones.
Note that this is NOT a concern with high impedance headphones, including 300 Ohm and 600 Ohm models, which are more properly matched to the higher output voltage. With 300 Ohm or 600 Ohm headphones, the output level with the resistors bypassed will only be a few dB higher, and you will receive the benefit of better damping.
I remember a thread (which I can't retrieve just now) where somebody asked whether or not to insert the supplied straps when driving headphones.. I argued against that on the basis of power calculations. Another guy argued in the other direction on the basis of sound quality. I now think he was right, and I was wrong. If the 220 Ohm resistors are left in line, the amp's output impedance is in fact 220 Ohm, which is dramatically high. The frequency response of the headphones will be adversely affected, even the 600 Ohm ones. It is generally accepted that the amp's output impedance should be 1/8th that of the headphones at the most. This is a damping factor of 8, which would already be considered way too low for ordinary speakers in order to get a good electrical damping. So I revise my opinion, but in order not to risk destroying the headphones, it is probably better to stick to the highest impedance cans you can afford. |
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Post by creimes on May 28, 2019 11:59:03 GMT -5
So what about the HIFIMAN cans like the HE4XX ones I have at the moment, being planars they do like power but the impedance of them is low, so I'm assuming not a good match for the A-100 I have ?? Chad You are indeed correct. "Modern thinking" is that a headphone amplifier should have a very low output impedance. (I personally prefer them that way).
However....
Vintage equipment, up through the 1960's or 1970's, virtually always derived the headphone outputs from the main outputs - through dropping resistors in the 100 - 250 Ohm range. This offers very little damping to the headphones, and can also result in a significant variation in frequency response due to the interaction between that output impedance and the impedance of the headphones.
Because of this interaction the actual frequency response, and the variation from flat, will depend on the impedance curve of the particular headphones you connect.
As such, it delivers a sort of characteristic sound, which is quite popular with some fans of vintage equipment, and some people actually purchase vintage receivers so they can get the vintage headphone outputs on them. If you look, for example, on Head-Fi, there are whole discussions dedicated to "using vintage gear to drive headphones".
(At the time, it was generally done that way to cut costs, because high quality low cost small IC amplifiers weren't yet available.)
With the resistors in-line, the A-100 will mimic this performance, with most of its pros and cons (although the main amps on the A-100 are a lot quieter). If you install the jumpers and bypass the resistors the A-100 will sound like a modern high quality headphone amplifier. However, as a consequence of its power capabilities, it will be "dangerously powerful" for low impedance headphones. Note that this is NOT a concern with high impedance headphones, including 300 Ohm and 600 Ohm models, which are more properly matched to the higher output voltage. With 300 Ohm or 600 Ohm headphones, the output level with the resistors bypassed will only be a few dB higher, and you will receive the benefit of better damping.
I remember a thread (which I can't retrieve just now) where somebody asked whether or not to insert the supplied straps when driving headphones.. I argued against that on the basis of power calculations. Another guy argued in the other direction on the basis of sound quality. I now think he was right, and I was wrong. If the 220 Ohm resistors are left in line, the amp's output impedance is in fact 220 Ohm, which is dramatically high. The frequency response of the headphones will be adversely affected, even the 600 Ohm ones. It is generally accepted that the amp's output impedance should be 1/8th that of the headphones at the most. This is a damping factor of 8, which would already be considered way too low for ordinary speakers in order to get a good electrical damping. So I revise my opinion, but in order not to risk destroying the headphones, it is probably better to stick to the highest impedance cans you can afford. |
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Post by jj2106 on May 29, 2019 1:32:54 GMT -5
Well, if I were you, I would leave the 220 Ohm resistors in line.
If the impedance curve of your cans is reasonably flat, they will still sound OK.
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Post by garbulky on May 29, 2019 13:49:04 GMT -5
So what about the HIFIMAN cans like the HE4XX ones I have at the moment, being planars they do like power but the impedance of them is low, so I'm assuming not a good match for the A-100 I have ?? Chad You are indeed correct. "Modern thinking" is that a headphone amplifier should have a very low output impedance. (I personally prefer them that way).
However....
Vintage equipment, up through the 1960's or 1970's, virtually always derived the headphone outputs from the main outputs - through dropping resistors in the 100 - 250 Ohm range. This offers very little damping to the headphones, and can also result in a significant variation in frequency response due to the interaction between that output impedance and the impedance of the headphones.
Because of this interaction the actual frequency response, and the variation from flat, will depend on the impedance curve of the particular headphones you connect.
As such, it delivers a sort of characteristic sound, which is quite popular with some fans of vintage equipment, and some people actually purchase vintage receivers so they can get the vintage headphone outputs on them. If you look, for example, on Head-Fi, there are whole discussions dedicated to "using vintage gear to drive headphones".
(At the time, it was generally done that way to cut costs, because high quality low cost small IC amplifiers weren't yet available.)
With the resistors in-line, the A-100 will mimic this performance, with most of its pros and cons (although the main amps on the A-100 are a lot quieter). If you install the jumpers and bypass the resistors the A-100 will sound like a modern high quality headphone amplifier. However, as a consequence of its power capabilities, it will be "dangerously powerful" for low impedance headphones. Note that this is NOT a concern with high impedance headphones, including 300 Ohm and 600 Ohm models, which are more properly matched to the higher output voltage. With 300 Ohm or 600 Ohm headphones, the output level with the resistors bypassed will only be a few dB higher, and you will receive the benefit of better damping.
If I'm not mistaken the planars are why people buy this amp because of the power it has when the jumper is bypassed. I think I heard some people using it to drive the HE-4xx. While I think one person had a problem with noise when the jumper was bypassed. |
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Post by creimes on May 29, 2019 14:04:33 GMT -5
So what about the HIFIMAN cans like the HE4XX ones I have at the moment, being planars they do like power but the impedance of them is low, so I'm assuming not a good match for the A-100 I have ?? Chad If I'm not mistaken the planars are why people buy this amp because of the power it has when the jumper is bypassed. I think I heard some people using it to drive the HE-4xx. While I think one person had a problem with noise when the jumper was bypassed. So are you saying bypassed as in not having the jumpers installed, if I remember correctly having the jumpers in is what gives you the full power right. Chad |
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Post by garbulky on May 29, 2019 14:12:45 GMT -5
If I'm not mistaken the planars are why people buy this amp because of the power it has when the jumper is bypassed. I think I heard some people using it to drive the HE-4xx. While I think one person had a problem with noise when the jumper was bypassed. So are you saying bypassed as in not having the jumpers installed, if I remember correctly having the jumpers in is what gives you the full power right. Chad My bad. What you said is correct |
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Post by creimes on May 29, 2019 15:33:20 GMT -5
So are you saying bypassed as in not having the jumpers installed, if I remember correctly having the jumpers in is what gives you the full power right. Chad My bad. What you said is correct I'll have to try installing the jumpers and see how it is, right now it doesn't seem bad but with the HE4XX I do need to turn the volume dial more than with my Shure SRH440 haha. |
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Post by jj2106 on May 30, 2019 1:23:29 GMT -5
If your cans are lo-impedance and you install the jumpers, please start with the volume set to 0, and slowly increase the level until you feel comfortable.
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Post by sockemdog on Mar 1, 2020 0:34:37 GMT -5
So what about the HIFIMAN cans like the HE4XX ones I have at the moment, being planars they do like power but the impedance of them is low, so I'm assuming not a good match for the A-100 I have ?? Chad If I'm not mistaken the planars are why people buy this amp because of the power it has when the jumper is bypassed. I think I heard some people using it to drive the HE-4xx. While I think one person had a problem with noise when the jumper was bypassed. Yeah, mine had a very low buzz to it on my HiFiMan headphones with the resistors bypassed. I never consulted Emotive on this, just put the jumpers back in and buzz was gone. However, I was testing it being fed from a DC-1 DAC and I preferred the DC-1 headphone stage over the A-100. |
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Post by vcautokid on Mar 1, 2020 3:25:41 GMT -5
If your cans are high impedance rock on with the bypass. 32 ohms or there abouts leave the jumpers in place. The A100 will do fine with 32 ohm cans with the jumpers in place. The noise floor of the A100 comes into play with my 32 ohm planars and duh, of course it would. However on high impedance Senns and Beyer Dynamics for instance bypassing the resistors is fine. Your mileage may vary. Experiment carefully to see how you work out with this. The A100 is one of the more powerful options out there when used judiciously. Most cans today are more efficient for a larger audience out there that use like IEMs and mobile devices to drive them. I do it all for the record and use bluetooth at work because of the objectionable white noise levels on top of the HVAC cranking. The Al00 is heaven sent for anyone driving very demanding cans. Less demanding ones work too of course. Heck the A100 drives speakers a treat too. Remember? Best desk amplifier for little money for instance.
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Post by hondaman01 on Aug 17, 2022 15:20:16 GMT -5
I got the a100. I've been using it now as a headphone app driving a set of 600 ohm headphones without looking inside and putting in jumpers but now that I've read this article I might try it see how it sounds I've never done it so it ought to be interesting thank you very much for the information you gave me. Only have the one set.
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Post by DavidR on Aug 17, 2022 16:50:05 GMT -5
I got the a100. I've been using it now as a headphone app driving a set of 600 ohm headphones without looking inside and putting in jumpers but now that I've read this article I might try it see how it sounds I've never done it so it ought to be interesting thank you very much for the information you gave me I love my A100. I even use it with a tube Pre and speakers. |
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KeithL
Administrator
Posts: 9,938
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Post by KeithL on Aug 18, 2022 9:34:19 GMT -5
I think you'll be very pleased... although, whether there is a significant difference or not will depend on the specific headphones you have. Just note... HEED THE WARNINGS if you use several different pairs of headphones. With high impedance headphones you won't notice much of a difference in Volume with and without the jumpers... although there may be a significant difference in how they sound. But, if you accidentally connect a pair of normal low impedance headphones with the jumpers in, you could damage them, or they could play unexpectedly loud. I got the a100. I've been using it now as a headphone app driving a set of 600 ohm headphones without looking inside and putting in jumpers but now that I've read this article I might try it see how it sounds I've never done it so it ought to be interesting thank you very much for the information you gave me |
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Post by vcautokid on Aug 18, 2022 14:02:24 GMT -5
Super high impedance Senns and the like are perfect candidate for the A100 with the mod. 32 ohm cans or around there even the 80 ohm Beyer Dynamic DT770 the A100 will drive just fine in stock mode.
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Post by hondaman01 on Aug 20, 2022 14:55:03 GMT -5
I think you'll be very pleased... although, whether there is a significant difference or not will depend on the specific headphones you have. Just note... HEED THE WARNINGS if you use several different pairs of headphones. With high impedance headphones you won't notice much of a difference in Volume with and without the jumpers... although there may be a significant difference in how they sound. But, if you accidentally connect a pair of normal low impedance headphones with the jumpers in, you could damage them, or they could play unexpectedly loud. I got the a100. I've been using it now as a headphone app driving a set of 600 ohm headphones without looking inside and putting in jumpers but now that I've read this article I might try it see how it sounds I've never done it so it ought to be interesting thank you very much for the information you gave me |
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Post by garbulky on Aug 20, 2022 15:26:29 GMT -5
I think you'll be very pleased... although, whether there is a significant difference or not will depend on the specific headphones you have. Just note... HEED THE WARNINGS if you use several different pairs of headphones. With high impedance headphones you won't notice much of a difference in Volume with and without the jumpers... although there may be a significant difference in how they sound. But, if you accidentally connect a pair of normal low impedance headphones with the jumpers in, you could damage them, or they could play unexpectedly loud. We’re you trying to post something? I don’t think it took |
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