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Post by PinkFloyd on Sept 26, 2010 20:36:53 GMT
Claus, As Frans says, best to fit output resistors  I went straight in with the 75ohm ones and haven't tried any other values as 75R sounds PERFECT with my HD250ll linears and the HD-600. IIRC I sent you a few different values to try? Wouldn't it be optimal to match the resistance to the headphone used ? I.e 300 ohm for hd-600.? Or 32 for using grado or k701 Not necessarily. This is "one" area that is down to personal taste. The de facto (industry standard) used to be 120 ohm output impedance. Quite a lot of designs, these days, "boast" zero ohm impedance..... means NOTHING (and in quite a LOT of cases zero ohm is not good)...... This is one area that is ALL about "trial and error" and only YOU can decide what OP (output impedance) is good for YOUR ears. 75 ohm (to my ears) is a good starting point. This is the beauty of DIY, you can tweak simple things like "two resistors" until you are blue in the face and it won't cost you more than a few pence. There is no such thing as an optimal output impedance... it is dependant on a lot of factors (your EARS / perception of sound being one of those factors) so don't be afraid to experiment here and let your EARS be the judge. With the Panda my lowest range would be 10 ohms and my highest 120 ohms..... try out all the values in-between and see what suits your own listening preference. Pinkie. |
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Post by Deleted on Sept 26, 2010 20:41:35 GMT
Pinkie is right.. Output impedances do not need to match those of the headhones. This kind of impedance matching is only needed for digital and video/RF transport through cables (50 Ohm or 75 Ohm) Experiment away..  Each HP and person has it's own 'sweet spot'  56 to 82 Ohms is quite 'universal'. Some HP's are designed to be driven from 120 Ohms (K701 being one of those) and others perform better at lower impedances.  |
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leo
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Post by leo on Sept 26, 2010 20:42:47 GMT
also worth comparing values if you have several different pairs of headphones , trying to get the one which works well with all of them
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leo
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Post by leo on Sept 26, 2010 20:43:37 GMT
Bugger , too slow  |
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Post by Koolind on Sept 26, 2010 20:53:28 GMT
Oh.. I see.. I was thinking that I might make an ohm switch or something like that, but maybe it doesn't really make that much of a difference.. ? I remember having seen a couple of Chinese amps where you can change between several values depending on the headphone.. maybe its just a silly special feature selling point though ?
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Post by PinkFloyd on Sept 26, 2010 21:06:42 GMT
Oh.. I see.. I was thinking that I might make an ohm switch or something like that, but maybe it doesn't really make that much of a difference.. ? I remember having seen a couple of Chinese amps where you can change between several values depending on the headphone.. maybe its just a silly special feature selling point though ? No! an "ohm switch" is a good idea..... If you have more than one pair of 'phones.... go for it! I am assuming the average Panda builder has "one" pair of favourite 'phones..... would you like a diagram of how to wire up a rotary switch to cater for a wide variety of OP impedances? No problems at all. Just don't want to turn this thread into a "run before you walk" type effort..... let's get the basic build done first Pinkie. |
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Post by Koolind on Sept 26, 2010 21:18:06 GMT
Good point.. surely the first thing to do is getting it up running! Then when its working I might try it out.. I actually use 3 pairs of headphones on a regular basis, so it could be a convenient feature if the difference shows to be worth it..
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Post by clausdk on Sept 26, 2010 21:26:20 GMT
Claus, As Frans says, best to fit output resistors I went straight in with the 75ohm ones and haven't tried any other values as 75R sounds PERFECT with my HD250ll linears and the HD-600. IIRC I sent you a few different values to try? I have mounted a 69 OHM resistor, no 75 but an 80, 100, 120, 39, 22 and 47 instead.. How does one know which resistance for which phones ?? Trial and error ? Can a phones sweetspot be calculated ? Interesting stuff.. |
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Post by Deleted on Sept 26, 2010 21:28:45 GMT
What headphones are you using Claus? You mentioned light bass so I wondered what you were using.
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Post by PinkFloyd on Sept 26, 2010 21:35:07 GMT
Claus, As Frans says, best to fit output resistors I went straight in with the 75ohm ones and haven't tried any other values as 75R sounds PERFECT with my HD250ll linears and the HD-600. IIRC I sent you a few different values to try? I have mounted a 69 OHM resistor, no 75 but an 80, 100, 120, 39, 22 and 47 instead.. How does one know which resistance for which phones ?? Trial and error ? Can a phones sweetspot be calculated ? Interesting stuff.. What 'phones are you using and what does it sound like to YOUR ears with the 70R fitted? |
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Post by PinkFloyd on Sept 26, 2010 21:39:19 GMT
To "my" ears..... 75 ohm suits most headphones. Let's not get carried away here.... we are "generaly" looking for a CATCHALL impedance which will suit most phones.... 75 ohms is my preferred value for most 'phones.
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Post by PinkFloyd on Sept 26, 2010 21:44:21 GMT
Can a phones sweetspot be calculated ? Yes! start at 75 ohms and either work down or up to 120ohm you will soon find your sweetspot Pinkie. |
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Post by clausdk on Sept 26, 2010 22:13:56 GMT
What headphones are you using Claus? You mentioned light bass so I wondered what you were using. my übermodded HD660, but it is way to early to make any comments about the sound.. It suited the JVC dx1000 very well later tonight maybe one should make a box with 25 headouts with different resistors ??, on with the drilling ;D ;D |
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Post by Deleted on Sept 27, 2010 7:24:43 GMT
the 69 Ohms is likely to be a 68 Ohms resistor as this is a standard value.
To make a 75 Ohm resistor with standard resistors you can use 2 resistors of 150 Ohm in parallel.
There is no way to calculate optimal output resistances per HP.
Like Mike said .. trial and error by ears is the only way.
If you make a switch 4 to 6 positions will be more then enough:
10 Ohm
33 Ohm
47 Ohm
68 Ohm (or 75 Ohm ?)
100 Ohm
120 Ohm
should be more then adequate.
In case of a 4 pos switch (or 4 outlets with different resistors if you don't like to use a switch)
22 Ohm
47 Ohm
68 Ohm (or 75?)
120 Ohms
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Post by Deleted on Sept 27, 2010 7:53:08 GMT
I did this on the Jaycar SCHA bulid. Using a rotary switch thus...  I rigged the resistors in series, incrementally, though I only used 3 positions (well, sort of 4 because I had 33R on the board) For Frans' 6 position switch that would be on the following lines; 1) 10R 2) 22R = 32ohm 3) 15R = 47ohm 4) 22R = 69ohm 5) 33R = 102ohm 6) 22R = 124ohm |
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Post by Koolind on Sept 27, 2010 8:16:34 GMT
The highest suggestion for the OP untill now is 124. As said earlier i think that its ood that one wouldnt try to match the impedance of the headphones (i am not questioning your answers). I.e. my AKG K340's has an impedance of 400. Shouldnt they then peform their best at an equally high OP ? Clearly i just dont know enough about electronics, but by my logic that would have made sense  Can anyone explain why this isnt so.. Or is this just "the way it is" (to advanced for a novice to understand anyway, in other words) |
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Post by Deleted on Sept 27, 2010 8:50:55 GMT
The highest suggestion for the OP untill now is 124. As said earlier i think that its ood that one wouldnt try to match the impedance of the headphones (i am not questioning your answers). I.e. my AKG K340's has an impedance of 400. Shouldnt they then peform their best at an equally high OP ? Clearly i just dont know enough about electronics, but by my logic that would have made sense Can anyone explain why this isnt so.. Or is this just "the way it is" (to advanced for a novice to understand anyway, in other words) koolind Many modern headphones are designed to work best with the specified IEC standard of 120 ohm output impedance, irrespective of their own impedance. K701 and AT W1000 are 2 examples of this. Actually, you can fine tune the tonal balance a little by varying the output impedance. As a general rule, reducing the output impedance to a lower preferred resistance value gives the impression of having increased the high treble, and increasing the output impedance gives the impression of a low end improvement, or a little less treble. SandyK |
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Post by Koolind on Sept 27, 2010 10:33:21 GMT
SandyK - Oh ok.. I think that i get it now. And still then it could be fun to have a possibility to change the sound a bit to my liking for each headphone.. I will look forward to trying it out when i get to that state..  |
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Post by PinkFloyd on Sept 27, 2010 20:50:23 GMT
Just noticed your "light bass" comment Claus...... Maybe this was before you fitted the 68ohm resitors? The bass response on the Panda I have is probably the deepest, tightest and most musical I have heard through a pair of headphones.... it's flawless IMO. You know how I "like" my bass..... this was the first thing I noticed about the Panda... the "bass"! I was hoping it wouldn't be a toppy type of listen and it isn't I have, primarily, been listening through the HD-250 ll linears (which are THE uber bass meisters IMO) but even with bass shy 'phones like the K-501 / HD-600 / SR-225 etc. it is still the nicest presentation I have heard from a headamp. The sheer "gravitas" and "largess" of the presentation is definitely a few gears up from most of the amps I have listened to over the years. The Panda is the only headphone amp I want to listen to at the moment.... anything else just seems to take the scale of the event down a few notches as if, somehow, the headstage, the detail, the width, the depth, the emotion, the grunt, the slam, the PRAT and the musicality has been "filtered"..... much like the opposite of a loudness button..... listening to my other favourite amps is as if I have pressed a "compress" button. It's hard to explain but, basically, the Panda gives me the clearest, most honest insight into the music..... as I previously said, it's like going from a Rogers LS35A to a Tannoy Westminster. Mike. |
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Post by Deleted on Sept 27, 2010 21:01:16 GMT
That's why I asked you about your headphones, Claus. The only thing with the output stuff is that I find the differences very subtle. ie' when I put an in line resistor via an adaptor, the difference isn't in yer face, so I'm not sure that the resistor would put enough bass in for Claus.
Presumably Mike, the one you just put together is a standard version, or did you do a capacitor jobby on it?
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Post by clausdk on Sept 27, 2010 21:47:42 GMT
Just noticed your "light bass" comment Claus...... Maybe this was before you fitted the 68ohm resitors? It was before the resistor and it was with my modded Superlux and I just came from the JVC Dx1000, I do not find it light in bass anymore.. |
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Post by PinkFloyd on Sept 27, 2010 22:05:43 GMT
Just noticed your "light bass" comment Claus...... Maybe this was before you fitted the 68ohm resitors? It was before the resistor and it was with my modded Superlux and I just came from the JVC Dx1000, I do not find it light in bass anymore.. Soooo..... does it sound "shit"?, does it sound "good"? Any observations? |
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Post by clausdk on Sept 27, 2010 22:18:00 GMT
It was before the resistor and it was with my modded Superlux and I just came from the JVC Dx1000, I do not find it light in bass anymore.. Soooo..... does it sound "shit"?, does it sound "good"? Any observations? It sounds nothing short of FANTASTIC.. Only problem now is that I have wasted so much cash on inferior amps. . . . . . |
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Post by PinkFloyd on Sept 27, 2010 22:20:25 GMT
Soooo..... does it sound "shit"?, does it sound "good"? Any observations? It sounds nothing short of FANTASTIC.. Only problem now is that I have wasted so much cash on inferior amps. . . . . . Sounds like she is firing on all four |
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Post by clausdk on Sept 27, 2010 23:29:11 GMT
It sounds nothing short of FANTASTIC.. Only problem now is that I have wasted so much cash on inferior amps. . . . . . Sounds like she is firing on all four I do not know if there is some placebo in this, but I had one of those rare moments, like when you did put on your first decent headphones and you thougth "wow this sounds goooood" Like the first time you go past 200KM/h in a car.. The first time you leap from the 3 meter platform I want more of those moments.. |
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I went straight in with the 75ohm ones and haven't tried any other values as 75R sounds PERFECT with my HD250ll linears and the HD-600.
Can anyone explain why this isnt so.. Or is this just "the way it is" 