solderdude
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Post by solderdude on Sept 9, 2015 5:08:31 GMT
Hi Crea,
Welcome to the forum.
It kind of depends what you want to achieve.
If you want a bit (1-2 dB) more bass you could use the high output R setting.
Should you want to have a more neutral sound than low output R will be the best setting.
The BW of the HD600 reaches way up but the 'speed' of the HD600 is determined by the voicecoil inductance.
BW setting thus will depend on your taste and used DAC perhaps.
If you want more bass (in the direction of the HD650) then removing one or all 'foamies' in the rear of the driver also works but difficult to reverse and does alter the damping.
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Post by crea78 on Sept 9, 2015 14:06:53 GMT
Thanks for the reply Frans. Someone posted this over at Head Fi for the HD650 and was wondering if it can be the same for the HD600.
High or Low input gain
Wide BW
Low Output Impedance
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solderdude
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Post by solderdude on Sept 9, 2015 21:16:18 GMT
The HD600 and HD650 have a slightly different signature.
The HD600 can be closer to the HD650 when the HD650 is driven from low R and the HD600 is driven from high R.
Writing a VERY long article on the HD650.
I am at page 47 and still not done.....
The gain setting depends on the source used and how much 'usable' volpot range you want.
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Post by luckbad on Sept 11, 2015 6:08:11 GMT
Howdy! Got the Polaris in today. This is a really beautiful amplifier and I love all the configuration options.
As far as output resistance is concerned, what does changing it do? It's obviously loudest at Low.
Why would I want to change it between the three settings?
Taking a few examples...
Fostex TH600 @ 25 Ohm
Sennheiser HD650 @ 300 Ohm
JVC HA-FXZ200 @ 16 Ohm (IEMs)
What is the cost/benefit of changing output resistance?
Thanks!
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Rabbit
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Post by Rabbit on Sept 14, 2015 11:38:13 GMT
I have to say that the noise floor on the Polaris is way down. I'm using a th900 with it, which picks up gnats coughing as far as amps are concerned. I always detect low level hiss due to the very low impedance of these cans, but adjust the Polaris to low gain, and it's the quietest I have around here. It really is.
High input gain, low output gain and it is top notch with the Fostex.
As far as output impedance goes, I use 'low' for the Senns. Some prefer higher. It's a preference thing really. Some hear nothing.
Adjust the gain though to minimise noise on the Fostex.
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solderdude
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Post by solderdude on Sept 14, 2015 12:41:38 GMT
As Rabbit said it's a preference thing at times and a technical thing for other headphones. It all depends on the impedance of the headphone and how much it varies and at which point in the frequency range. For the HD650 the difference is small yet noticeable. More detailed measurements on the HD650 effect is found HERE (there is a section about impedance) For the TH600 I would recommend the low setting but the mid setting could possibly also be used, a smidgeon more bass. I do not recommend the high setting. The bass might become too much/flabby. For beyer DT880 and Grado's as well as the HD600 the high setting may well work best. The JVC may work best on low R setting but may be a bit too loud (to little room to adjust the volpot) For this I proposed a small extension cord with 2 resistors in it. Don't know if Jeremy is going to make IEM attenuators himself as well though. If the sound signature does not change (too much) in a negative way you could get better volume control on mid or high R setting. This will lower the output level substantially for this headphone. For the HD650 the level differences are small, just 2.5dB I thought. |
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Post by luckbad on Sept 14, 2015 17:07:29 GMT
Thanks man. So for output resistance, High would give you the most bass on the HD650, while low would give the least (if I'm reading it correctly).
What's super interesting to me is that the HD650 (in the amazing PDF you linked--thank you for that) plays louder with 120 Ohm output resistance. I hear the opposite. The Low setting on the Polaris is the loudest of the three and it gets 1-2dB quieter each step. Is that just my mind playing tricks on me because of the frequency response changes? I have to turn the volume pot up quite a bit more with the High R settings vs. Low.
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Rabbit
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Post by Rabbit on Sept 14, 2015 17:19:10 GMT
If you set the output impedance to low, the sound will be louder.
120 ohms output impedance will be softer.
If you set the input gain to high, it will play louder than having the input gain at low.
If you set the gain of the amp to high, it will be louder than having the gain set at low.
There are three variables that will all alter the volume.
a) output impedance
b) gain
c) input gain.
There is also bandwidth which epwill alter the sound but not volume.
It looks as though you are confusing which gain is which.
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Post by luckbad on Sept 14, 2015 18:29:33 GMT
Rabbit, I'm mostly referring to the HD650 PDF.
It's saying you gain ~2.5dB with 120 Ohm output impedance vs. 10 Ohms. Correlating that to the R setting on the Polaris, it seems like the High (120) should be louder than the Low (0.1) based on the text.
What you're saying--and what I've experienced--makes logical sense.
I'm kinda wondering if what I'm seeing/reading is inverted from the HD650 PDF.
I'm after maximum bass. Is that the Low R setting on the Polaris, or the High R setting?
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solderdude
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Post by solderdude on Sept 14, 2015 18:30:49 GMT
Thanks man. So for output resistance, High would give you the most bass on the HD650, while low would give the least (if I'm reading it correctly). What's super interesting to me is that the HD650 (in the amazing PDF you linked--thank you for that) plays louder with 120 Ohm output resistance. I hear the opposite. The Low setting on the Polaris is the loudest of the three and it gets 1-2dB quieter each step. Is that just my mind playing tricks on me because of the frequency response changes? I have to turn the volume pot up quite a bit more with the High R settings vs. Low. Nope your mind isn't playing tricks. That's exactly what happens. Perhaps I could expand the article a bit further and show this as well. Maybe along with other questions that may arise by people reading the article. It was me playing the trick because I wanted to 'overlay' the 2 plots to show how the sonic character changed. In reality, when the plot would be measured at the exact same volpot position, the 120 Ohm curve would be shown 2.5dB lower in amplitude. If I showed that plot it would make more sense amplitude level wise BUT the difference in tonal balance would not be as clearly visible as it is now. So some trickery on my part to illustrate tonal change (and how small it is, yet not insignificant) |
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solderdude
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Post by solderdude on Sept 14, 2015 18:34:56 GMT
Maximum bass (and warmth) = removal of the rear foam + High R setting.
This will give around a 3dB bass boost/warmth boost opposite stock+ low R.
Funnily enough I don't like the warmth/blooming/bassy part of the HD650 and want it less colored but with a more intense and above all really deep and sturdy bottom end.
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Post by luckbad on Sept 14, 2015 18:36:31 GMT
Ah ha! When you mention that 150 Ohm is 2.5dB higher, you mean YOU adjusted it, not that the output volume is higher.
I read most of that PDF and it's frickin' awesome, dude. I think it's about time for me to remove the foam from the rear of the driver to pick up the bass a bit.
Wish there was a good sub-bass mod for the HD650. That's actually the only thing I dislike about it (the sub-bass rolloff).
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solderdude
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Post by solderdude on Sept 14, 2015 18:45:08 GMT
EQ or the bottom part of the article. Should you ever go for the Kameleon (or the filter add-on Jeremy still plans to make) I can whip you up with an alternative filter that'll make your teeth rattle. No subbass roll-off on mine  |
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Post by luckbad on Sept 14, 2015 18:52:32 GMT
If I can use the Kameleon from my regular amp (Polaris or Audio-GD C-2) and just put in a teeth-rattling filter, that's pretty much exactly what I want. I particularly love sub-bass of ~75Hz and below. I don't like if bass is raised beyond ~250Hz (usually ~125Hz, really).
That said, the HD650 is already exactly where I want it other than sub-bass.
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solderdude
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Post by solderdude on Sept 14, 2015 19:02:52 GMT
Jeremy is planning to make an 'add-on' in G1217 style that can take Kameleon modules.
It is fed from Garage 1217 amps and simply goes between the source and amplifier.
Knowing Jeremy it may take another year before he even starts on it.
Have been thinking about designing it myself but in a Kameleon enclosure.
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