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Old 14th November 2009, 02:14 AM   #91
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i talked to mundorf today and showed them the hammond specs.
they will try to wind a coil on an i-core bobbin with 300mH, 6 Ohm or come up with another solution. they find the project interesting at least.
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Old 14th November 2009, 02:36 AM   #92
Salas is offline Salas  Greece
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I guess they know they need an air gap on the cores. Have sent you the CCTs with some notes BTW. Seen your interest about coils in Riaa on syn's thread it was I think. I had 2 highly regarded LCR tube phonos from Japan under scrutiny, they had nothing they did better, to the contrary. I believe your friend had done better. About electronics distortion minimals and their thresholds VS the much more in transducers level, both for speakers and cartridges, the logical order is different IMHO. Less distortion for comparable CCT complexity must not be considered as a merely smaller additive on a bigger problem, but as an indication of more linearity so not to further interact with the main problem. You are a renowned speaker designer. Could you recognise two different cdps or amps with adequately much lower self distortion than your speakers own, through them? If yes, its about how much info you save until reaching your speakers, for them and the room acoustics to truncate, not about that your speakers they can only pass some predetermined info quantity and that is all. IMHO of course. If on the other hand you could not, forget my non scientific hunches, have a pilsener, relax.
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Old 14th November 2009, 04:38 AM   #93
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Distortion in speakers has another nature and origin then the distortion in amplifiers so curiously you CAN hear improvements to your amp over "distorted" speakers.
by the way, the pair i build for my self that is not so bad in distortion at all. at cruising level distortion is under 0.5% mostly 2nd and very little (under 0.1%) third from 70Hz to 10kHz.
on the other hand, yes, buy youself a good speaker and place it in an optimum position in a good sounding room and you have done your homework. i sometimes hear sytems of my employes. they of cause all have my speakers. one of them has an ALDI (famous german discount chain) 39,-€ dvd player and a cheap hometheatre amp and the sound he gets is 100 times better then what i regulary hear at shows and dealers. it`s not perfect at all but it has emotion and character so does the musical job of comunicating.
apropro coil: i think what mundorf will try to make it by simply winding the copper directy on an open bar so there is a HUGE airgap. we call coils made that way I-Punkt
. if that does not work they will try to wind it on a transformer or a ferite bobbin
P.S: as i already said, i had my lisening checked on Professor Klippels website and i can not diferenciate better 0.1% low order distortion . curiously i hear differences in cables, resistors, op amps etc. very easy and developed a particalar taste : big-focussed soundstage, dramatic dynamics, low colouration and good tonal balnce, wide bandwidth etc.
P.S: i also listened to some exotic japanese phonoamps and was surprised by the colouration. maybe asian people have other prorities although i have several asien friends that share my taste in sound. i sold a lot speakers to asia, especially taiwan, japan and korea so that fact remains a mystery
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Old 14th November 2009, 04:54 AM   #94
Salas is offline Salas  Greece
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They have other vowels, other living space, some atonic high pitched traditional instruments, they love delicate aesthetics, we simply can't know their priorities if we don't live with them enough. I have gathered they maybe give priority to etheral midhighs and cosy midbass. Maybe what FR speakers need, that they use a lot.
Distortion and noise numbers in electronics are not thresholds to listen to IMHO. Just indications to more information. If you get the MPP without any topological or bias changes to measure 6dB less THD and noise, just because some new bjt allows you so, the music is going to appear more informative and bolder. Same impact if you get it down to 0.05% from 0.1% or down to 0.025% from 0.05%.
To me its simply 6dB better, not just even less than less enough. If you manipulate it to measure better with more or different circuit, then you can't compare directly, its another pre. So we like 0.1% of that food and not 0.01% of another food. But we surely notice 0.05% better in the food we like. Then again don't take me any seriously, those are DIYer's non scientific hunches as I wrote before.
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Old 14th November 2009, 05:02 AM   #95
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it´s that old thing about quantity and quality
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Old 14th November 2009, 01:56 PM   #96
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Hi Salas !
i have worked a little on the pre filtered supply. i would work with a double bridge.
only one channel is shown, i would go for double mono. the other option would be to use the pre filter for both channels and then use 4 shunt regulators, two for each channel (+- supply). what do you think is the best way ?
do you have a recommendation for the diodes in the bridge, for the transformer and what do you think about the filter caps across the bridge directly behind the secondary of the transformer ? sorry for the many questions but it will safe me a lot of time and i trust you.
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Old 14th November 2009, 02:15 PM   #97
Salas is offline Salas  Greece
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Check FFPF60SB60DS Fairchild diodes. I would avoid toroidals, good EI, or R-Core for best. 1u caps I use in my tube gear across the secondary, they work there. One good Transformer double bridge and prefilter with 2 +/- shunts, i.e 4 sides, one symmetrical reg per channel, is a good compromise that will allow resources for better quality parts where it counts. See if you like the thing as a whole with the phono first and then you can double your Tx, chokes, etc. seeking some little more isolation. The shunts when fed by CCS don't disturb much what is before them, and have very low output impedance for what is after them. If you apply carefuly and twist the force/sense wires directly to the second stage power & star ground nodes (even a coax for the sense if you see any nasties on the scope when probing the B+, B-) the impedance stays in spec and it is very difficult to have modulation from second stage to first. Then again you need to decouple towards the 1st stage with RC so to drop voltage, hence you get even more guarded. I prefer a good star earth node for each channel and one set of regs, than many applied, leading to more laborious grounding. At 300mA shunt's CCS setting each side, 4 total, make sure you got a thick metallic box floor to bolt the T0247s down or adequate sinks. 6.75W dissipation per side per reg you got to channel away.
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Old 14th November 2009, 03:26 PM   #98
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ok, good advise . i was planning to use only one transformer and pre regulation stage anyway.
as you say that can later be more eleborated if desired
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Old 14th November 2009, 06:02 PM   #99
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what do you think about these ?
Hammond 229D24 data sheet 3997
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Old 14th November 2009, 06:57 PM   #100
Eva is offline Eva  Spain
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I'm just curious: 300mH 6 ohm, ok, this is quite high inductance, but how high saturation current has to be? This is the parameter having more impact on choke size and type of core.
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