Help choosing project.

[wakibaki]

1. There's nothing relevant on the page you linked. 
 
2. These aren't Grados.
 
What does 'high-end harshness' look like on any instrument, let alone a DScope?
 
@BCG27 What makes your 2 word answer more constructive than mine? Why would an increased capacity on the part of the amplifier to control the movement of the diaphragm result in high-end harshness?
 
'Overdamped' is a condition in resonant systems. An overdamped audio transducer has a reduced low-frequency response, but 'overdamped' in this context refers to the mechanical damping provided by the transducer structure or indirectly by the enclosure, and has nothing to do with amplifier 'damping factor', which is a misnomer. 'Damping factor' refers to the relative capacity of an amplifier to control the diaphragm or other moving part of an audio transducer. 'Overdamped' is meaningless in the context of amplifier output impedance.
 
So 'close' was overgenerous.
 
w
 

 

[dsavitsk]

'Overdamped' is meaningless in the context of amplifier output impedance.

Tell it to Nelson Pass

Critical damping -- that resistive combination of electrical source impedance, suspension friction and acoustic load -- occurs when you apply a step pulse to the voice coil and the cone's motion doesn't overshoot. Under-damping results in bass notes that hang around a little longer than the amplifier intended. Over-damping has good transient bass control but also suffers a significant loss of bottom end response. Generally, we want something in-between, something closer to critical damping. Whether we slightly over-damp or under-damp seems to be a matter of taste.


The need for electrical damping is different for each type of loudspeaker and acoustic environment. High-efficiency full-range drivers are more easily damped than other types due to their powerful efficient motors and light cones. Looking at their bass response curves, we conclude that they are easily over-damped, resulting in excessive loss of bottom end. This partially explains the preference for tube amps with such loudspeakers.

 

[qusp]

yes but we arent talking about amps tuned to be current sources here; running on current drive, are we? as usual i think AMB's generalisation (not you specifically AMB, but the generalisation) does not help to clarify. its true some research seems to point to current drive amplifiers working quite well with certain types of very high efficiency very low impedance (including the box or lack thereof) speaker, but i dont know that this applies to grados and dont know that i give the phrase 'overdamped' much credence either
 
speaking of Papa though, a man i do indeed admire and have build several of his designs, have you seen his latest Sit incarnation? a 4 box X'd SS amp with 122 of his custom Static indiction Transistors per channel for nearly 1kw into 2ohms and about 10% efficiency haha. the photo i saw has the reseller standing next to the stack and it was up to his shoulders 

 

[tomb]

Quote:

yes but we arent talking about amps tuned to be current sources here; running on current drive, are we? as usual i think AMB's generalisation (not you specifically AMB, but the generalisation) does not help to clarify. its true some research seems to point to current drive amplifiers working quite well with certain types of very high efficiency very low impedance (including the box or lack thereof) speaker, but i dont know that this applies to grados and dont know that i give the phrase 'overdamped' much credence either
 
speaking of Papa though, a man i do indeed admire and have build several of his designs, have you seen his latest Sit incarnation? a 4 box X'd SS amp with 122 of his custom Static indiction Transistors per channel for nearly 1kw into 2ohms and about 10% efficiency haha. the photo i saw has the reseller standing next to the stack and it was up to his shoulders 

With respect:
Where is AMB in this conversation? 
Who is talking about tuned current drive?  The question was output impedance.
Why isn't a very-high decay rate (purrin's tests) synonymous with overdamping - or at the very least, "well-damped?" 
 
 

 

[Willakan]

Wait a second:
The problem of the OP is that he wants less highs.
He is using a computer.
 
Equalisation seems like the blindingly obvious, free solution, rather than playing silly buggers with tube amps.

 

[qusp]

Quote:

With respect:
Where is AMB in this conversation? 
Who is talking about tuned current drive?  The question was output impedance.
Why isn't a very-high decay rate (purrin's tests) synonymous with overdamping - or at the very least, "well-damped?" 
 
 

my apologies i mentally inserted AMB when your post wasnt on the page in front of me. what do you mean where is current drive? As I understand it; as output impedance rises but load impedance stays the same low value, the amplifier looks more like a current source than the typical voltage source. some achieve this with tubes and output transformers to match the load impedance, some achieve this by using little or no global feedback (maybe just a little degeneration), some add a resistor (not the best idea)
 
Nelsons many experiments with current source amplifiers, mostly low gain common gate current power buffers that prefer an active preamp with a little gain in front of them (of which he has released many) are likely what gave rise to his comments you read. your generalisation that grados dont play well with SS or low output impedance is what i was talking about; its nothing but a personal opinion shared by another person. i'm sure you'll find some that agree with you, although grado themselves dont seem to, but i'm equally sure you will find some that disagree and some will have written papers about that too.
 
sorry but DF and its interaction with dynamic transducers and their electrical and physical impedance (the cabinet/cup) is not completely understood by many more knowledgable than you or me, it does not appear to be as black and white as wakibaki mentioned as a phenomenon of complete amplifiers, but as a force it by definition has more control of the diaphram. perhaps something else is going on here, but i dont think you can make such a generalisation, or even use such a phrase as 'over-damped' what does that even mean?
 
in this context for a low impedance load conventional thought is that you can not have an overdamped amplifier for low impedance loads, as the ideal is as close to 0R as reasonable. zero is unobtainable of course and other factors outside the amp stop that from ever being a reality, but better to start low imo. its much more achievable with most headphones than most loudspeakers though, due to the lack of a crossover; a rule broken by multidriver iems and loudspeakers with digi XO's
 
but really i was just calling you on the generalisation, that is all.
 
 
 
 

 

[qusp]

i'm willing to concede that having too much physical control over a structure that isnt so well physically damped could be a problem, due to causing resonance. could that be a factor in old grados? i.e. the rapid change in direction and acceleration becomes a negative effect

 

[tomb]

Frankly, I'm astounded at the line of argument that doesn't recognize over-damping.  Maybe a simple review is in order:
http://en.wikipedia.org/wiki/Damping
A key statement is "Overdamped (ζ > 1): The system returns (exponentially decays) to equilibrium without oscillating. Larger values of the damping ratio ζ return to equilibrium slower."
 
Certainly, to any reasonable reader that would indicate that an overdamped system is not desirable.  Now, if you combine a physical system (headphone driver) that is naturally well-damped (again, I cite purrin's tests that Grados have a very fast decay, which the rest of you seem to ignore) and you combine that with an outside controlling force (amplifier) that also has a very high damping ratio (low impedance, high damping factor), then you could potentially have an overdamped system.  In the case of the headphone, the driver is not going to return to normal state (whether in vibration or excursion) as quickly as it otherwise might (with less damping force applied).  If in addition, another signal is applied (very likely with music) before said driver has returned to its normal state, then you have the definition of distortion and the result is that it has increased.  Most of us tend to describe this as harshness, but perhaps that term is in question in this discussion as well.

 
" ... we arent talking about amps tuned to be current sources here; running on current drive, are we?"  It could be misleading based on your punctuation, but I took this to be a rhetorical question on your part.  If so, then the natural implication was that we really were discussing tuned current sources, which we weren't.  Its mention seems off-subject, at best. 
 
Quote:

Wait a second:
The problem of the OP is that he wants less highs.
He is using a computer.
 
Equalisation seems like the blindingly obvious, free solution, rather than playing silly buggers with tube amps.

No offense, but you should probably read a bit more closely.  The OP specifically stated, "sibilant nature of the highs ..." in the second sentence of his post.  I simply pointed out that there was another view on whether to pursue low-output impedance - one that I share and can confirm through experience.  Then the rats' nest started in the conversation.
 
Since I'm being accused of generalization, too, I may as well go on with my real issue in this discussion and others.  There seems to be quite a trend lately of relatively recent users (not you, qusp) that seem to take delight in promoting conflicting views over those that have been well established through years of effort on this forum (DIY).  I'm not talking about cables - that's always been an issue and will remain so.  Yet, all of a sudden there's no value in an active ground, opamps and soundcards are suddenly just as good as top-of-the-line amps, there's no value in high-performance power supplies, there's no difference in DACs if the frequency response is the same ... I could go on and on, but I'm getting a bad attitude already and need to quit posting for awhile.  It just burns me when some of this gets recommended to a noob and hardly anyone (but a few) seem to think it's worth pointing out a different view - one that was earned by many people on this forum through years of development, design, and building. </end rant> 

 

[Willakan]

 
Quote:

No offense, but you should probably read a bit more closely.  The OP specifically stated, "sibilant nature of the highs ..." in the second sentence of his post.  I simply pointed out that there was another view on whether to pursue low-output impedance - one that I share and can confirm through experience.  Then the rats' nest started in the conversation.

As sibilance occurs in a documented section of the audioband, I think my statement remains valid.
As for everything else: drastic-overstatement-of-position-you-don't-agree-with-straw-man'ing aside, I'm all for improvements that can be quantified under controlled conditions. 

 

[tomb]

Quote:

 

As sibilance occurs in a documented section of the audioband, I think my statement remains valid.
As for everything else: drastic-overstatement-of-position-you-don't-agree-with-straw-man'ing aside, I'm all for improvements that can be quantified under controlled conditions. 

EDIT: Never mind - I just need to quit posting.  This is not productive and went way beyond the OP's question.
 

 

[qusp]

first i think i need to clear up my generalisation comment; because it appears as though my (not AMB specifically, but the generalisation) bracket comment didnt serve its purpose, but rather further confuse. what i meant by that was that 'as usual generalisations do not serve to clarify' not 'as usual, AMBs generalisations do not serve to clarify' see the difference there?
 
so we are talking about a flaw in the headphone mechanism (rigidity and not large enough magnet?) response interacting with a force that is already trying to change direction and thus causing resonance that is subjectively interpreted as harshness? i posted this above your response as an addendum and it seems to be a fairly in line what you have posted above. i'll admit i dont have much experience with grados, because honestly i find them harsh in the upper midrange no matter what they are plugged into and typically and not surprisingly, too forward. This combines with the scratchy/sweaty and/or yellow foam and zero isolation to make me have no patience with them. so if we are talking about an effect that is peculiar to grados or similar, then this is why this is making no sense to me. In all my builds i have found with both very low impedance like my jh13, or moderately high as with my hd600 the lower the outputZ, the better the performance to the point where i will remove resonance damping resistors from the output
 
sorry i simply dont have the time to read the artical tonight, but i'll try to make some time tomorrow arvo, its just that the whole damping factor argument in relation to speakers, has been thrown around a lot lately and frankly i see it as something that is not totally understood because the experts argue endlessly too and there is certainly no consensus. It is fairly commonly mentioned that without much by way of physical inertia/impedance as with headphones, its effect is fairly benign and i certainly have no lack of bass with essentially zero outputZ in my gear, with my ears, so i'm left scratching my head. Nelson above doesnt mention headphones specifically, but his definition WRT loudspeakers pretty much rules out an effect on headphones of sufficiently low weight, high strength and enough power in the magnet to overcome the fairly insignificant forces. but perhaps my experience just doesnt include it
 
i think i did confuse you a bit with the wording. i was meaning we werent talking about a current buffer, rather than current source.
 
yeah 
 
i know what you mean with the influx of junior objectivists and its happening over at DIYA as well, except thankfully they seem to be keeping to segregated areas. glad you didnt lump me in with them, i know you would be a popular target with that type wanting to earn their stripes lol. i try to provide counterpoint in those threads for as long as i can handle it, but i can see both sides to a degree, i'm conflicted.

 

[Willakan]

So the subjectivists (read: tweako audio voodoo cultists) see audio objectivists as a sort of disease? How ironic.
Back on topic, I still don't see why equalisation or other forms of DSP cannot fix the OP's problem.

 

[qusp]

well at the moment some of you are acting like it yes, invading happily subjective threads to interject regurgitated rhetoric many do not even understand.
but yes at the moment i'm starting to find it a bit much over at the other place too, most do not stray outside of the designated threads to participate in the forum at large, or give back in any way. I tried to find a person in jokeners GB thread that had donated to the forum aside from myself and didnt find a single one.
 
Apparently you eat your own as well, to the extent 2 of the group buy organisers currently owing quite a lot of money to the group while one is missing and the other is too much of a coward to post in the thread and has taken 4-5 months to still not pay back everything. ive never had any problem with any GB ive used, but 2 in a row for the same project screwed me over. so you'll excuse me for not being excited.
 
but i'm not speaking of objectivists in general, some are able to accept that people are people and let them have their beliefs and/or accept their subjective findings are simply not inline with their views and leave it at that. some happily even coexist throughout DIYA and here. Its just the brand that seem to like to enforce their views (in many cases not even their views, just something theyve read) on others happily enjoying their diy hobby to satisfy themselves, without caring how it looks on a scope, or whether the improvements or changes they are making meet the objectivist definition of 'audible'. the other side is not free of guilt either, but you rarely if ever see them going out of their way to kill the fun of objectivists

 

[Willakan]

 
Quote:

well at the moment some of you are acting like it yes, invading happily subjective threads to interject regurgitated rhetoric many do not even understand.
but yes at the moment i'm starting to find it a bit much over at the other place too, most do not stray outside of the designated threads to participate in the forum at large, or give back in any way. I tried to find a person in jokeners GB thread that had donated to the forum aside from myself and didnt find a single one. 

Agree on people regurgitating stuff, but that happens on both sides of the divide: look at subjective equipment reccomendations. If you buy into all that then surely reccomending equipment you've never heard is a cardinal sin?
 
I am fascinated by your comments about participation. Considering the forums at large tend to be full of subjective sillyness or stuff that isn't of great interest to objectivists (sure, a uber-low noise power supply is interesting from an academic perspective, but I'm not really interested in how people suppose it sounds) the fact that objectivists don't tend to participate can be rather easily excused: the only way they would possibly want to participate tends to lead to complaints, as you note. You can't have it both ways

.

 

[qusp]

nah thats crap sorry and if its really your view, you obviously havent had much of a look either. diya has plenty of content and active threads that stay well away from baseless opinionated garb and/or contain enough technical->highly technical information sprinkled through it provided first hand by industry professionals with much deeper knowledge than RS (for one example, the engineers that designed the chips used in the wire amps are regular contributors, Dustin, the designer of the ES9018/12/16, the designers of the Hypex Class D amps, speaker designers of the same calibre and of course Nelson, EUVL,  etc etc) to make it worthwhile to read and participate in regardless; most will answer questions directly
 
being able to have these types of people's ear is a boon if you are interested in anything past the painting by numbers presented in the O2 project ie. you do not have to learn a single thing about diy to build the O2, yet some seem to emerge with a smugness. not across the board, not at all, i never painted a broad stroke, just mentioned a worrying trend that started here, but because RS is banned here, the venue has mostly been DIYA.
 
 

Spoiler: deeper%20but%20enough%20OT

 
i'm involved in several projects there currently and every single one is either fully characterised as with the 3 new wires with their uber-high performance, or provide such a great exploration of good performance with simple circuits as to provide a really nice study of the behaviour of the building blocks at the heart of this stuff. at the moment i'm finding the SEN/CEN jfet IV circuits i'm playing with fascinating. they are pure current conveyers with floating supplies allowing them to be modulated by the load. performance is just over -105db and it seems a bit more can be squeezed out. eeking those last few bits by experiments with power supply and bias networks is very interesting and highly educational. sure i have several single opamp IVs that can do better, but nowhere near as satisfying as deadbugging some super low noise buffered references for the jfet gates.
 
i dont like this divide thats been generated and i also reject pure objectivity as a fallacy that is just as pointless to pursue as pure subjectivity, you may as well give up now and go home to listen to your soundcard from 2001. stray too close to either extreme and you dont grow IMO