Rabbit
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Post by Rabbit on Dec 20, 2015 14:00:06 GMT
I think in general some amplifiers can have problems with low impedance cans because of the high current flow demand. Hiss is my main problem with some low impedance cans. Some of my low impedance cans never hiss, others do. It seems related to the sensitivity and frequency outputs of the can as well. Those with higher treble emphasis seem to hiss louder-I suppose that makes sense. Same for me Howard. Low impedance, which seems all the rage nowadays creates another problem. Noise!! I also feel that higher impedance headphones are a little quicker on the whole and give better start/stop information. Maybe that's just me. For home use, I'd rather use higher impedances if I'm honest. Maybe even the th900 would improve at a higher impedance?  I never had the Solstice at home here with the others to compare. I liked it (as I do all of them) a lot, but the Polaris is better than the Ember with low impedance because it has more options with input and output levels. Once you get it down to a reasonable gain, it's actually very quiet. I love it with the dt990 though. Very lively and controlled!! |
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Post by Deleted on Dec 20, 2015 16:28:35 GMT
I remember Jeremy telling me you can change the gain modules on the Ember 2 to something lower (might not eliminate tube noise of course). Wonder if you can do the same with Polaris? I suspect the default low gain (2.25x after attenuation I think) would still be a bit too high for my liking. 1x gain would be perfect for me if customisation is possible. A high impedance TH900 Ian? Probably never happen as it'd be just too good for mere mortals to handle I reckon  Would like to see either a shorter or detachable cable on the Fostex though. The one on the THX00 is like a flippin' skipping rope and I found the weight a bit disconcerting in terms of strain relief. Although as I found out today when removing one of the ear cups the cable's actually knotted inside so that should stop any tugs from yanking the cable right out. |
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Post by techboy on Dec 20, 2015 16:35:18 GMT
I remember Jeremy telling me you can change the gain modules on the Ember 2 to something lower (might not eliminate tube noise of course). Wonder if you can do the same with Polaris? I suspect the default low gain (2.25x after attenuation I think) would still be a bit too high for my liking. 1x gain would be perfect for me if customisation is possible. A high impedance TH900 Ian? Probably never happen as it'd be just too good for mere mortals to handle I reckon Would like to see either a shorter or detachable cable on the Fostex though. The one on the THX00 is like a flippin' skipping rope and I found the weight a bit disconcerting in terms of strain relief. Although as I found out today when removing one of the ear cups the cable's actually knotted inside so that should stop any tugs from yanking the cable right out. In Ember 1 I have the option for Low and High Gain. Are there other options that can reduce the gain at Low setting? If possible, I would be interested in turning to 1x gain as well. Does it require soldering or just simple stuff? |
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Post by Deleted on Dec 20, 2015 16:47:07 GMT
I asked Jeremy about this a while back. Don't think he'd mind me quoting him verbatim:
"But the downside is that the gain modules are only for the V2 Ember. The version 1 does not contain a socket for the module on the PCB. The input attenuation / gain can be changed by manually soldering resistors in however"
Whilst doing so will obviously reduce volume levels and give you more control Jeremy / Frans have both made it clear when I've discussed this with them that tube noise will not necessarily be eliminated. In some case it might help but no guarantees.
Another option is to use an attenuating adapter with the Ember 1 and there was some discussion on that a couple of pages back. Again tube noise could still be an issue and some adapters increase the output impedance which might not be desirable.
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Rabbit
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Post by Rabbit on Dec 20, 2015 16:49:14 GMT
I'm not sure about the gain options for the Ember, but I do remember a resistor being fitted in order to do this. I'm not sure which side of the tube the resistor goes because no matter what input gain you have, tube noise will be consistent. Frans can clarify that.
TBH, I use the Ember for higher impedances and Polaris for lower. If I want lower, I resort to the Fiio e12a which is an excellent little amp with no noise or even an O2 which gives zero noise because of the way that it is put together.
Generally, tubes are way better with higher impedance, supply good voltage swings. They're not so good at supplying current for lower impedance stuff.
The adapter idea works 100% but it also raises the output impedance which 'could' affect the sound of your headphone. Some it seems to affect more than others. For instance I found the Grados actually improve at high output impedance. So an adapter improves them in two ways; no noise and more mellow sounding. Other headphones don't react that much.
You can either use a fixed adapter or one I used was a variable one which you listen on, with no music. Turn up the resistance until the noise has gone, then use the amp. That way, you're just using as much resistance as you need for the headphone. That is also different for each headphone.
Not ideal, but at least the hiss goes. I'd stick with higher impedance headphones with it though. I also use the adapter with cheap, crappy digital radios that have amplifier sections in them that hiss like snakes.
Techboy, it might make more sense to try an adapter first before doing anything permanent. You might find with some headphones that the value of resistor is a bit critical and the last thing you want is to have an amp that loses its punch. If I increase the adapter, that can be the effect that it gives.
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Post by Deleted on Dec 20, 2015 16:59:40 GMT
I did find the ifi attenuator more or less removed any hiss I was hearing but in fairness the tube I was using wasn't particularly noisy to begin with.
I tended to stick with higher impedance phones with the Ember too and used the O2 or iCAN for anything less demanding. I tried it more out of curiousity as I was interested to see how the Pandora would sound with a bit of tube flavour thrown into the mix.
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Rabbit
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Post by Rabbit on Dec 20, 2015 17:02:41 GMT
Same as me, Mark. It makes sense really. Use an amp like the Ember performing at its best.
Ican amp section can be hissy too btw. My idsd analogue section isn't the best and the Nano is downright poor. Fine with higher impedance but you can't use it with lower impedance without getting hiss. The gain is controllable but low gain doesn't affect the hiss.
I really like the e12a actually. Lower gain and extremely low noise. O2 can be a bit squeaky clean!!
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Post by Deleted on Dec 20, 2015 17:26:05 GMT
I think you had the Nano (battery powered) version of the iCAN didn't you Ian? Believe that's quite noisy.
The one I have is the Micro iCAN (mains only) and is designed with senstive IEMs in mind. Very quiet but not quite as black a background as the O2. A bit more boxy sounding than the O2 and you know yourself that's not exactly got the widest sounding of amps.
The E12 is an amp that I've heard good things about but being an amp only would mean an additional box (DAC) in any portable set up, which has always put me off.
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Post by techboy on Dec 20, 2015 17:32:27 GMT
I use a HD 650 but end up listening at 8/9 o clock because anything more is too loud. Doesn't matter, not a deal breaker.  And I have a FiiO E12 but I don't like it at all. It seems overly warm to me. |
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Rabbit
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Post by Rabbit on Dec 20, 2015 18:16:45 GMT
I have the Ifi Nano as well as the idsd Mark. I thought you'd sold the Ican. Changed your mind?
I must try the idsd feeding the Polaris one day, I think. The X3 or X5 going out digitally are terrific.
Sounds like a terrible waste of resource but I feed the digital out from the tv into the idsd. Both tv and freeview radio sound great.
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Rabbit
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Post by Rabbit on Dec 20, 2015 18:23:07 GMT
And I have a FiiO E12 but I don't like it at all. It seems overly warm to me. Ok. I'm wrong then. |
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solderdude
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Post by solderdude on Dec 20, 2015 22:29:26 GMT
I'm not sure about the gain options for the Ember, but I do remember a resistor being fitted in order to do this. I'm not sure which side of the tube the resistor goes because no matter what input gain you have, tube noise will be consistent. Frans can clarify that. Yes the gain module, or more correctly, attenuation module lowers the input signal. The reason for this is that the tube itself has a rather high gain. Reducing that gain (feedback) also lowers the added harmonics and thus the typical 'tubesound'. The gain of most tubes is a fair bit too high for DAC's with 1V, 2V or even higher output voltages and you would end up using only the first small part of the volpot. L-R tracking isn't the best down there ...  So ... to lower the overall gain (not the gain of the tube) the input attenuator lowers the input voltage. On Ember one the 'overall gain' can be set in 2 steps that are determined by resistors. If one wants more attenuation (= less overall gain) 2 resistors need to be changed. For Ember 2 the attenuation module can easily be changed to another one with more (or less) attenuation... a handy feature making it more 'configurable'. For noise this has no influence at all. The tube amplifier part behind the attenuator (and volpot) will not be influenced by the attenuator. The adapter idea works 100% but it also raises the output impedance which 'could' affect the sound of your headphone. Some it seems to affect more than others. For instance I found the Grados actually improve at high output impedance. So an adapter improves them in two ways; no noise and more mellow sounding. Other headphones don't react that much. You can either use a fixed adapter or one I used was a variable one which you listen on, with no music. Turn up the resistance until the noise has gone, then use the amp. That way, you're just using as much resistance as you need for the headphone. That is also different for each headphone. Not ideal, but at least the hiss goes. I'd stick with higher impedance headphones with it though. I also use the adapter with cheap, crappy digital radios that have amplifier sections in them that hiss like snakes. Techboy, it might make more sense to try an adapter first before doing anything permanent. You might find with some headphones that the value of resistor is a bit critical and the last thing you want is to have an amp that loses its punch. If I increase the adapter, that can be the effect that it gives. It is not difficult to make an output adapter that lowers the output voltage (and thus lowers the gain and noise) and still keep a rather low output resistance. This low output resistance is a MUST for most (but not all) IEM's and high sensitivity (often low impedance) headphones. The recipy for one is HEREEven do-able for beginners to soldering. I suggested to Jeremy that he should be making them so the waaaayyyy to powerful (and noisy tube) amps can also be used safely and noise free on IEM's and sensitive headphones. So far he didn't have time to make something nice for it but think it would be a useful addition. |
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Post by techboy on Dec 21, 2015 5:34:01 GMT
Now that I have started using the analogue volume pot with the iPad and FiiO E12 as well. It is pretty good. Not very powerful. And lacks something the Ember has, perhaps. But a tad bit cleaner. Not bad for the price. |
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Rabbit
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Post by Rabbit on Dec 21, 2015 8:57:38 GMT
I think you had the Nano (battery powered) version of the iCAN didn't you Ian? Believe that's quite noisy. The E12 is an amp that I've heard good things about but being an amp only would mean an additional box (DAC) in any portable set up, which has always put me off. The sad part is that the Nano 'looks' the part and is really well built. What I didn't like is the fact that Ifi produce some great units and you'd think there would be the same attention to quality on the Nano. All 'I can' say is 'what a let down that one was'!! It's nice having phono inputs and a full sized output god the headphone, but noise is an issue. Fine with higher impedance though. I have the E12 and the E12a which is slightly less powerful and a tad more refined than the E12. It's handy in that it's easily 'strapped on' to the player and makes a solid bundle on the move. The O2 isn't great in that respect as a portable amp. I just go from digital out to line out from the Fiios and TBH, it's really not at all bad like that. |
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Post by Deleted on Dec 21, 2015 9:22:58 GMT
The Nano does seem a bit ill conceived to me and the hiss is disappointing. ifi revised the Micro to handle lower impedance headphones and to my mind the Nano seemed the ideal candidate for the same treatment.
Agree about the O2. It's more transportable than portable really. Fine for those times when you want to sit out in the garden though. I currently have a 'desktop' version which does away with the internal batteries in favour of a full size headphone jack, stereo rca out and moves the power socket to the rear. Makes it far more practical for home use.
With regards the iCAN I removed it from sale due to some issues I experienced with it. You might remember me posting about some audible hum and static issues when flicking the switches? Looked like a dodgy pin on the power supply but after replacing that the static issue remained (hum had gone though). Frans had kindly offered to take a look at it for me but I figured by the time I'd paid for 2 way international shipping and the new power supply it'd have likely cost me as much to fix it as I'd make from any sale, so decided to retire the amp and just sell off the power supply.
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