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Post by Deleted on May 15, 2011 10:28:37 GMT
As Ian correctly points out adding resistors to the portable isn't the right thing to do (K701) For the Mossfet/Bossfet a 100 to 120 additional resistor will work (like on the Panda and AHA). Perhaps the 18V Neco (with 2x 9V) a 75 Ohm (or something close) could just work.
I just extracted the schematics from the portable and it is a standard opamp configuration. From a technical point of view (if I were selling them) I would insert a 10 Ohm resistor between the output of the amp board and the output connector.
There is a technically quite sound reason for doing this. As the opamps output is directly connected to the output plug, the feedback loop is vulnerable to the capacitance of the headphone cable which can cause instability with certain opamps, ringing or overshoot that may even enter the audible domain. Adding this small resistor (I thing Ian heard correctly by adding the 38) makes the opamp more stable and less dependent on the capacitance of the headphone cable, which can be high with the thin wiring (wires close together) of certain buds / ie's. Neco has limited the bandwidth of the amp which helps a bit in stability issues but could be improved markedly this way.
Anyway... it's what I would do... if it were mine. 10 Ohm is actually quite low (about the minumum that should be used) and wouldn't affect the sound much but increase stable operation. 16 Ohm HP's max SPL would drop 4 dB, 32 Ohm about 2dB which is hardly noticeable. higher Ohmic resistors are not recommended for general use execpt for the 18V portable versions.
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Post by Deleted on May 15, 2011 10:56:21 GMT
I would have thought that would be standard practice with a non buffered opamp.As Frans points out, most opamps don't like directly driving cable capacitance, The series reistance value is more typically in the range of 47 to 100 ohms with preamps, DACs etc. Alex
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Post by Deleted on May 15, 2011 11:04:31 GMT
Oh yes .... I forgot to say. Different headphone volumes drop by differing amounts, so that must be the headphone impedance working in conjunction with the added resistance. Frans, is the Neco opamp going directly out so it's in effect 0 ohms? I guess what I'm driving at is that it wouldn't have harmed to put even a 10 ohm in line. 38 ohms improves the sound for sure and if I could go higher, I would. I'm very comfortable with 38 ohms though on a portable. Bigger would make sense for mains driven amps perhaps. The effect is not a massive - 'Oh listen to that bass,' or 'The treble has doubled'. It's just more comfortable and natural to listen to. The biggest change is the ie8 which is rated at 16 ohms I think. See what you've got me up to after lending me that device Frans? Ian
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Post by Deleted on May 15, 2011 11:09:45 GMT
Yes it will be very close to 0 Ohm due to the feedback (perhaps around 0.1 Ohm if measured )
how high the added resistance can become depends on the headphone (resistance and efficiency) and max SPL, consider short peaks in classical recordings that you don't want limited in any way (called headroom) Most 'pop' recordings are so compressed there are hardly any peaks to speak of.
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Post by Deleted on May 15, 2011 11:19:34 GMT
Yes, it does compress given half a chance ... and can turn nasty sounding!!
Perhaps 38 is too much for a Neco then? Perhaps that's why I'm so keen on low impedance, easy to drive headphones on the Neco. It's just a gut feeling and it feels better to me.
IMO, the next generation Neco portable needs to be 18v.
It's all such a compromise of power and resistance. A minefield.
Is it possible to cram two resistors into a right angled mini jack for portables? One problem with portable is the size of the plugs and then putting resistors in line puts a stress on the jack plug.
The more I've played around with the ie8, the more I feel that perhaps the makers should develop some kind of plug that has resistance in line to provide the kind of sound I'm getting from the ie8 with 38 ohms. I have a feeling that the Bose iems do this. There is a lump in the cable.
I don't mind the lowering of sensitivity, although I can see that it could be a problem for people without amps and going from headphone out!!
It's a shame that amp makers and headphone makers don't make the specs a little more available so we are aware of headphone output impedance from the amp and the recommended impedance for the headphone.
I know that the German manufacturers have tried with the 120 ohm ideal but it's not plain with other makes at all.
Oh well, I've got to go. I'm taking the ie8's with me and resistors to listen to music and blot out people!!! I'm doing a bloody fete for the town all afternoon, outside, so it's going to be impossibly loud which I hate, so in with the ie8's to knock it down!!!
Ian
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Post by Deleted on May 15, 2011 15:55:37 GMT
perhaps SFR16 type of resistors could be fitted in a plug.
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elysion
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Post by elysion on May 15, 2011 16:02:33 GMT
As Ian correctly points out adding resistors to the portable isn't the right thing to do (K701) For the Mossfet/Bossfet a 100 to 120 additional resistor will work (like on the Panda and AHA). Perhaps the 18V Neco (with 2x 9V) a 75 Ohm (or something close) could just work. I just extracted the schematics from the portable and it is a standard opamp configuration. From a technical point of view (if I were selling them) I would insert a 10 Ohm resistor between the output of the amp board and the output connector. There is a technically quite sound reason for doing this. As the opamps output is directly connected to the output plug, the feedback loop is vulnerable to the capacitance of the headphone cable which can cause instability with certain opamps, ringing or overshoot that may even enter the audible domain. Adding this small resistor (I thing Ian heard correctly by adding the 38) makes the opamp more stable and less dependent on the capacitance of the headphone cable, which can be high with the thin wiring (wires close together) of certain buds / ie's. Neco has limited the bandwidth of the amp which helps a bit in stability issues but could be improved markedly this way. Anyway... it's what I would do... if it were mine. 10 Ohm is actually quite low (about the minumum that should be used) and wouldn't affect the sound much but increase stable operation. 16 Ohm HP's max SPL would drop 4 dB, 32 Ohm about 2dB which is hardly noticeable. higher Ohmic resistors are not recommended for general use execpt for the 18V portable versions. I was thinking of using a 120 Ohm adapter with the MOSFET/BOSSFET. The portable isn't ideal for the K702's anyway. Neco has already SOLD 18V portables. We've discussed them already on the forum, but no one here has bought one so far. I've asked Neco already if he's selling the 18V portable again. He will and told me that I can exspect a revised 18V portable within the next 1-2 months. That's probably the next amp which I'll buy. The portable really doesn't show the full potential of the K701/702. But it's not bad for such a small amp IMO. I wouldn't recommend the portable specifically for use with the AKG's. It's another story with the HD650's: IMO they DO sound great with the 9V portable, at least when using AD8160 opamps. The MOSFET with AD8160 sounds better with the HD650's (of course), but the portable is damn close. The HD580's do sound also great and I'm almost sure the HD600's will do too.
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Post by Deleted on May 15, 2011 18:16:57 GMT
Oh, I never saw them!! Presumably no recharging circuit? I think that 18v is a good way to go in order to try and retain good dynamic response.
I think you're right about 8610 and the Senns Christian. Tonally, they are fine together. I'd prefer more volts behind it though to gain (hopefully) a little more impact.
I had an 18v CMoy at one point and I must admit, it was a lively little thing. It just seemed to have more life in it than another 9v version that I had and seemed to be able to 'control' the headphones better. Whether it was psychological because it had more voltage or whether it was actually giving more impact is long forgotten now, so I'm just going from my own memory and experience of an 18v amp.
Ian
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mrarroyo
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Post by mrarroyo on May 15, 2011 19:12:05 GMT
. . . BTW Miguel - I think I've joined your club. I got an email from Colt calling me a 'pervert' for saying nice things about his spandex suit in his photo on another thread. ;D . . . Ian, Colt loves big booty babes in spandex but he will not admit it!
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Post by Deleted on May 15, 2011 20:44:03 GMT
Could this be him after his foam purchase?
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Post by Deleted on May 15, 2011 23:08:37 GMT
Take a shit? Threads still on? Does that make it a thread crap
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mrarroyo
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Post by mrarroyo on May 16, 2011 10:39:13 GMT
Big T&^S and bigger AZZ, that is wonderful. Thanks for sharing it.
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Post by Deleted on May 16, 2011 10:50:39 GMT
I think this thread is in serious need of a cleanup, especially as this is in a publicly accessible area. All the regulars here know that I am not a prude from private emails, but guy talk like this is best reserved for pubs and emails, where I would be happy to join in.(too damn far for the pub bit though!) Could be time for some late online conference type stuff again ? Alex
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Post by Deleted on May 16, 2011 12:28:34 GMT
OK Alex, I think you're right. Mike, we'd better put a hoover on this thread!! Apologies to anyone who may have come back and is offended. No harm is meant by such comments and I realise that it was started by me having a gentle dig at M!! I think it needs a cleanup Mike. Ian
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Post by PinkFloyd on May 16, 2011 13:08:59 GMT
Ok... just got the Dyson out and agree that the banter was a bit too close to the bone for public consumption, my apologies.
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Post by Deleted on May 16, 2011 14:10:04 GMT
Ok... just got the Dyson out and agree that the banter was a bit too close to the bone for public consumption, my apologies. Good on ya!! Ian
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elysion
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Post by elysion on May 16, 2011 16:00:08 GMT
Mike, we'd better put a hoover on this thread!! Did I miss something? ;D ;D ;D ;D ;D
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Post by Deleted on May 16, 2011 17:03:43 GMT
Mike, we'd better put a hoover on this thread!! Did I miss something? ;D ;D ;D ;D ;D We've all been in the shower and washed our mouths out with soap!! Ian
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Post by Deleted on May 16, 2011 23:12:49 GMT
Hi, Ian I received the opa227's today, and listened to them, installed in the Neco portable with the ie8's. To my ears, they seem to have the typical Burr-Brown laid back quality, though they do sound fairly neutral, with a tendency to sound a little tubby, which is probably good for jazz, pop, and rock, but not so good for classical, especially big orchestral works. They are not lacking in the treble -- it is there, reproduced faithfully, and I don't hear any serious roll-off at the top end, which seems to have almost too much of a sizzle. But, to my ears, they lack the transparency and impact of the AD8610's, and the tight extended bass of the AD843 (if installed in the Bossfet). I am sure that after a few hours of burn-in they will change, and everything I am saying now may not be valid after a few days of burn-in, so I will leave them in the Neco portable for a while. Right now the opa227's sound somewhat similar to the opa627's that I had (and still do, along with many others in my growing collection ) and liked for a while, but missed the impact and transient response of the AD8610's and the AD843's. Of course, I am sure things will change after I make some in line output resistors, etc. I am glad to have them, and will see if I can get them to sound a little more to my liking as they play-in. Cheers! Israel
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Post by Deleted on May 17, 2011 7:00:18 GMT
Hi Israel, Yes, they are slightly more 'round' sounding than the 8610. I actually prefer the 843 but can't run it in the Neco. (That's basically why I'd like an 18v version. I find the 8610 quite analytical and am not keen on cymbal sound from them. That is also probably because I do mostly listen to rock/jazz and tend not to use the portable for orchestral if I'm honest. I like to try and get as much dynamic range as possible on orchestral so use a mains driven amp more for that kind of stuff. Thing is that most rock is compressed to hell so you can get away with all sorts of things whereas jazz and to a much greater extent, orchestral, requires huge swings of voltage to provide that massive range of dynamics. I even hate the sound of my own stuff on disc. It's compressed and thin sounding with a nasty edge in the treble - nothing like the real thing and something like an opa227 kind of helps with that stuff. It's also quite a commonly used opamp in music - maybe I'm kind of attuned to it? It annoys me that music engineers often don't take the care and trouble to retain atmosphere and dynamics in their recording practice whereas orchestral specialists are much more attuned to acoustics and getting as good a dynamic range as possible. (mostly) Do you remember some recordings on vinyl, where orchestral movements of say, 30 minutes wouldn't fit easily on a record so they downed the volume and dynamic range in order to be able to fit it all on one side? The Suisse Romande used to do a lot of that!!! Result - quiet music with restrained dynamics and lots of surface noise!!!! Good old engineers eh? For me, tranfers of old vinyl stuff to CD has been quite disastrous and hearing myself transformed into this 'perfect' format has been the focus of a lot of argy bargy. Even new stuff doesn't seem to come up the same to me!! Maybe I'm getting old, but the 'accuracy' of CD just doesn't reproduce the guts of the real thing although I'm assured that it's all there!! Alex' experiments with digital rips has returned some of that vinyl feel for me so maybe the engineers have been right all along. The information is there but not necessarily being reproduced by our equipment (although I'm not using low end stuff). His experimenting is quite pioneering' in my eyes/ears. It would be really useful to get the original recording and listen to the ripped versions and compare to see how close they are getting. I suspect they are extremely close, although some guys don't hear any difference. My own feeling is that the format that was decided on was flawed at the start and we should have opted for better bit rates so then people like me wouldn't be trying to compensate with opamps!!! I think tonally, for me, I like the sound back a little so that I don't suffer from fatigue on long listening - something you wouldn't get on orchestral since the dynamics ar on much more of a variation than most rock stuff. I've also learned over the years that we kind of 'attune' ourselves to sound that tonally can be quite skewed and we can accept it as quite normal, but if dynamic range is missing, we can't accept it as a good recording. So I've kind of come to the conclusion that tonal isn't as important as dynamic range, which is why I say to people not to use something like a K701 on a portable. Tonally, you get the same kind of sound, but the dynamics at the top of well recorded music just turn edgy, prompring people to change opamps in an attempt to fix a tonal thing rather than dynamic. Maybe I'm guilty of that with op227? At work, I use the Beyer DT150 which is also a laid back headphone. Basically, you couldn't keep them on for long periods if the top end was gritty; plus the fact that they are extremely comfortable to wear for a long time. Before taking the opamp out, try some loud brass Mahler climaxes and then swap to AD8610 and see whether it starts to feel 'toppy'. That's what made me stick with opa227 in the end. Sorry - I just realised I'm rambling on .... but for me, it's the overall picture rather than just one component and I do feel that we compromise in order to make up for something else etc. The chain of events in sound reproduction, I think is very important which is why I rant on about matching, amps etc I suppose!! However, I suspect you're extremely savvy with all that eh? Regards Ian
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Post by Deleted on May 17, 2011 7:32:23 GMT
Consider the fact most pressings are done for 'the big public' and are thus (heavily) compressed and altered so it sounds accepatble to those (ordinary, no hi-fi people) on their gear.
In general, some Jazz affiliated lables and classical ones (even they use slight compression in some cases) are an exception.
The (real) dynamics of a live (classical) concert is hard to reproduce on most audiosystems because of the tremendous difference in SPL during the recording hence the 'alterations' made by most Studios and CD factories (even more so in vinyl).
One tends to find compressed music 'dynamic' and music with real dynamics, that is reproduced a LOT softer then the original sound, dull and lifeless.
So my opinion is: Don't blame the format/electronics or the musicians... blame the general public and those that try to please them. Look for the better labels / recordings for eargasms and if you don't care about eargasms just enjoy the creativity/music on the gear that suits your personal ears best. No harm in trying to achieve the maximum available SQ but sometimes other people already ruined it for you beyond 'repair'.
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Post by Deleted on May 17, 2011 8:04:40 GMT
Actually, that's very worrying given the public's love of downloads. There aren't many labels setting standards so the public have no choice but to accept compressed/loud recordings. It's a shame, but convenience wins over quality now. Ian
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Post by Deleted on May 17, 2011 13:17:55 GMT
Hi, Ian and Frans Some very interesting and astute remarks indeed! From all the comments, it becomes clearer how personal our individual tastes are, colored, if you wish, by our training, past experiences, profession, physical attributes, etc. Myself, having sat inside an orchestra for many years (not in front of the trumpets!!! ), and later on having to perform in a different format such as solo and chamber music, has formed in me a concept of sound quality expectations, and hence my preconceived ideas of what some instruments sound like in real life. Brass, or cymbals sound much different on stage than out in the audience, where some of the very high frequencies have been lost (they don't carry as well as the rest for acoustical reasons). But of course, you already know that. For example, neither of us really know exactly how our own individual voices sound, and, because of our own individual internal head resonances have a completely different 'picture' of it, so to speak, than what others perceive. Do you recall how shocking it was hearing a recording of your own voice for the first time? Was it what you expected? A recorded version of it, will only give us a resemblance of it, for a truly realistic version does not really exist -- it will come close, but in fact there will always be some distortion and some alteration because of factors such as listener's individual hearing characteristics, acoustics, etc. Hence, us performers, whether instrumentalists or vocalists, have a percept of our own individual tone quality that we produce, which is very different from what is perceived out in the audience. Ian, I did listen to some loud Mahler with the opa227's installed in the Neco portable, and I agree: the brass and cymbals are indeed smoother sounding. I am hoping that with the help of the inline output resistors I am planning to put together, I can alter the SQ enough to be able to use the more impactful and palpable sounding AD op amps, while at the same time taming the highs somewhat, but the laid back sound of Burr-Brown op amps simply is not exciting enough for me, for the reasons I mentioned above. I never felt laid back while for years playing first flute in a professional orchestra, where my livelihood (and my family's) depended on every note I played! The excitement is wonderful -- I wouldn't trade it for anything in the world! Perhaps I am seeking to reproduce that kind of feeling! This is the reason why I simply can not have music as background - I end up listening to it actively, and can not concentrate on anything else while it is playing! For me, listening to music is a full time occupation! It never helps me go to sleep -- the opposite! It wakes me up, even if it is a lullaby! I have indeed gone off on a tangent here, but it all goes to one conclusion -- that there isn't one! We are all different, thankfully! Cheers! Israel
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Post by Deleted on May 17, 2011 19:19:54 GMT
We are all different, thankfully! Cheers! Israel Oh definitely Israel. I've read your post a few times now and had another thought about how we like to hear sound. If like you, you are in the orchestra, you are used to hearing the sound very close up and so need to hear that treble detail whereas from the audience viewpoint, it's not as crucial. That could be it. I'm on headphones sometimes for very long periods and am probably 'trained' to accept less top end which makes it less fatiguing for long term use. (Especially at lifelike volumes) That's why I felt that you may not have like the ie8 actually. I was quite relieved that you felt happy with it actually. Mistakes are expensive at that level!! Ian
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Post by Deleted on May 17, 2011 20:13:48 GMT
If like you, you are in the orchestra, you are used to hearing the sound very close up and so need to hear that treble detail whereas from the audience viewpoint, it's not as crucial. That could be it. You hit the nail on the head! I am sure this is the case, and this is what I was trying to express in my last post, perhaps in too roundabout a manner! I'm on headphones sometimes for very long periods and am probably 'trained' to accept less top end which makes it less fatiguing for long term use. (Especially at lifelike volumes) I don't blame you for trying to protect your hearing! You must do what you can! Absolutely! Extremely loud volumes have always been very painful to my ears, but it is the extreme db levels of the high frequencies that can be the most offensive! That's why I felt that you may not have like the ie8 actually. I was quite relieved that you felt happy with it actually. I actually find that the ie8's are not at all lacking in treble, even at the extreme top, and have no complaints about them at all! Actually, sometimes, while listening to CD's remastered from analog recordings with the old vinyl RIAA curve left unaltered, I find that there is even too much sizzle on top! But, with a well engineered, and balanced recorded source material, I find them to be very pleasurable to listen with! All the Best! Israel
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