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Old 23rd November 2009, 04:30 PM   #221
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my Titan has 5.5 Ohm so 1:1 for john and syn
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Old 23rd November 2009, 05:27 PM   #222
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Quote:
Originally Posted by Joachim Gerhard View Post
here is that crazy phonostage jan :
http://digilander.libero.it/paeng/mc_trs.htm
Not crazy, creative! Finally something new under the sun!

jd
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Old 23rd November 2009, 06:18 PM   #223
Salas is online now Salas  Greece
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Noise would matter on horn speakers mainly from this point on. Balanced should give a 3dB penalty, isn't that right?
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Originally Posted by Joachim Gerhard View Post
why noise over horns should be more objectionable escaps me. yes, the noise from the power amp should be really low and they love class a and tubes but considering that the volume at the listening seat is the same the noise from the phonostage should subjectively be the same. one problem can happen: many horns that i have measured have a very ragged frequency response in the treble so some frequencies simply stand out more then others. such speakers can sound quite noisy i am shure.
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Originally Posted by syn08 View Post
Because horns have sensitivities of 96-102dB and hence the hiss is way more audible. HPS 3.1 and 4.0 are dead quiet in my Klipsch RF-83 horns (97dB), but everything over 0.4nV/rtHz is clearly audible, cartridge input shorted to ground, at maximum volume. I hate hiss.
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Originally Posted by syn08 View Post
Well, I do, and it's correct (both theoretical and practical). A 96dB speaker sounds twice as loud as a 90dB speaker, at the same power. And so is hiss. This is obvious even for those with tin ears like myself

You'd be very happy with BF861 cooled down via a Peltier device. My preliminary results are very good, I can tell that. Evacuating the condensation is not trivial, though.
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Originally Posted by Ultima Thule View Post
Logically I would have thought independently of the loudspeaker sensitivity we have to tune our little volume knob to get the same listening level, which would equalize out any difference in phono stage noise or anything else before the volume knob, right?

The only thing we can't equalize out is the noise produced after the volume knob, the noise in the power amplifier for instance.

btw the human ear perceives a sound pressure doubling closer to around 9 dB, don't remember right now the exact figures but I am sure Joachim knows that too.

Cheers Michael
Syn and I talk about how much it can be perceived near a speaker at full open system gain, so the speaker's sensitivity matters. Sort of a tell tale crude test of overall hiss. The head amp would be the most critical chain ring in such a case given all else is done right.

You talk hiss at a given arbitrary SPL as controlled by the volume pot for a range of speakers drivable. In that case, of course you are right, only rough HF peaks in some horn speakers would inflict a disadvantage and not their mean average sensitivity. I would add the defined directivity control on top of that, focusing more HF energy around the listening position instead of a more ''spread out'' power response by a dome tweeter in usual listening environments.

I have 95dB direct radiating speakers for instance. With only one 2SK170 in the head amp, still the hiss is only audible 10cm from the tweeter when I set the volume for about 90dB average at listening position.

Beyond the nuisance factor which is controllable and relative as in the above speak, I am sure that noise climbing up in the lows with Fets and triodes when collaborating with under 1Kohm source resistance (i.e. most MC), and especially under 100 Ohm, softens the bass slam. I got to use 4 in parallel soon that will help by sqrt n. BJTs are better with MC low but I don't mind much beyond 4 2SKs since the rest of my system is valve and the contributed hiss after the phono is not best, will rather dominate, but still adequate for my priorities.
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Old 23rd November 2009, 07:17 PM   #224
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here is that crazy phonostage jan :
http://digilander.libero.it/paeng/mc_trs.htm
It's not ultrapath though but parafeed. And what is a supertriode?
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Old 23rd November 2009, 07:25 PM   #225
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I have the data sheet for a 0.8 ohm phono cartridge in front of me. with a 350uV output at standard level. Go for it! Syn08 I also have 13 ohms and 40 ohms respectively, for Dennon.
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Old 23rd November 2009, 08:05 PM   #226
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ok, salas i understand now. but it is a party trick. we have a lot of customers like that in germany. they crank the sytem full and then complain that they hear noise then they put their ear near the tweeter. i just wanted to make shure that we understand each other and you made it clear. yes, syn, sell your stuff here. our bürocratic customers will love it. Accuphase is very popular here and i think that is one reason they took so much pain in eliminating the noise. well actually i have not heard or measured it and over 90dB THD/Noise seems a little odd to me when i see the specification. compared to what level? -60dB(1mV) or what.
to michael: yes it is that book
to john: that 0.8 Ohm and 0,35mV is a great combination for very high dynamics. they must use enormous magnets or very innovative solutions. is is a field coil design with DC feed?
to Bas: tomorrow in the pane i will study that circuit, i hope i understand it. never seen something like that and how will it sound ?
To all: have you heard about a therory that a little noise, distortion and DC offset helps a speaker to sound better because it is quite stiff and unlinear in the rest position. the dc will push it a bit out, the second harmonic will mask higher ones and the noise contibutes a dithering action that softens the suspension even further, makes it more "responsive" and masks higher harmonics too ?
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Old 23rd November 2009, 08:12 PM   #227
Salas is online now Salas  Greece
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Analog dither we should call the trick?
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Old 23rd November 2009, 08:52 PM   #228
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you name it. it will bring you in the hall of fame.
by for today. i have to pack for the states so not much posts for the next week but i will investigate scotts advice and hopefully make that circuit work when i am back.
exiting ride with you boy´s !!!!
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Old 23rd November 2009, 11:55 PM   #229
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To all: have you heard about a therory that a little noise, distortion and DC offset helps a speaker to sound better because it is quite stiff and unlinear in the rest position.
The incremental transfer function can easily be measured especially very near field with a sensitive mic. A dead zone would give crossover-like distortion something rarely(never) seen in any measurements that I have made. Due to reciprocity you could probably do just electrical measurements to see any effect.
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Old 24th November 2009, 04:54 AM   #230
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I measure speakers with the Klippel laser system. what i can see is that BL,Le and Cms do not have their maximum or minimum in the zero position very often.
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