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Old 10th January 2012, 11:01 AM   #4131
Previously: Kuei Yang Wang
 
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Hi,

Quote:
Originally Posted by galeb View Post
I know you've did it, but some idea on other area, like oscillator, power supply, or maybe digital data from SPDIF receiver to TDA...
There are other threads where you can find comments of mine on specifc solutions. This one here is John's gig (who incidentally does not care much for tubes, while I do).

Ciao T
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Old 10th January 2012, 01:37 PM   #4132
roger57 is offline roger57  Canada
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Quote:
Originally Posted by erin View Post
I found this to be one of the worst sounding resistors I ever heard. Just totally sterile. But that is just my opinion. YMMV.
I'm using a Mills MRA05 now and I think it sounds goo; not overly bright but and good in detail/resolving. Too bad the TX2575 is so pricey, it might be worth a try before discounting it.

I may also try a Riken or AMRG for grins....
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Old 10th January 2012, 01:38 PM   #4133
roger57 is offline roger57  Canada
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Quote:
Originally Posted by roger57 View Post
I'm using a Mills MRA05 now and I think it sounds good; not overly bright but and good in detail/resolving. Too bad the TX2575 is so pricey, it might be worth a try before discounting it.

I may also try a Riken or AMRG for grins....
Silly spelling error in post, resubmitted. No such thing as "goo" sound, unless you are a new mother.
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Old 11th January 2012, 10:28 AM   #4134
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Hi ThorstenL,

Quote:
The active load could have been used to improve the overall performance of the follower (White Follower, Gomes Stage) but is wasted here instead on fixing a problem (powersupply noise) that should not exist in the first place in well designed equipment.
I agree, circuits running on clean power supplies only have to cope with the passing signal and this is already difficult enough.

Fixing power supply noise with an Aikido driver stage works fine in theory, the problem is that it has to do this in practice as well. It is likely that low frequency noise is attenuated while higer frequency noise simply passes and inter-modulates with the signal being processed. This causes selective noise attenuation or coloring.

Also keep in mind that the circuit connected to the TDA1541A needs to offer inaudible noise levels, large bandwidth, fast settling time and very low linearity errors.

Amplifying low amplitude signals is likely to increase noise, limit bandwidth, increase settling time and increasing linearity errors.

That's why I no longer use this output stage concept.


Quote:
There are other threads where you can find comments of mine on specifc solutions. This one here is John's gig (who incidentally does not care much for tubes, while I do).
I applied tubes in the octal D-I DAC and DI8M projects. Balanced passive I/V conversion, balanced input stage (twin triode) followed by a Broskie buffer. Spent a lot of time with tube rolling and testing effects of different coupling caps. I used tubes that were selected for lowest microphony / noise and closely matched triode characteristics.

Later I experimented with Aikido amplifiers and DC-coupled tube amplifiers with OTL output.

Few days ago I even experimented with a balanced crystal oscillator based on a twin triode.

If tubes offer advantages over semiconductors in a specific application I wouldn't hesitate to use them.
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Old 11th January 2012, 12:06 PM   #4135
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Hi roger57,

Quote:
I'm using a Mills MRA05 now and I think it sounds good; not overly bright but and good in detail/resolving. Too bad the TX2575 is so pricey, it might be worth a try before discounting it.
I agree with erin, bulk metal foil resistors for passive I/V conversion sound detailed, yet sterile and "thin". This is a bit surprising as these resistors offer very low noise levels, low inductance and low stray capacitance. So other factors like resistor geometry may be causing this.

Carbon resistors are noisy, Riken or AMRG resistors with cool gold plated wires are no exception. When used as passive I/V resistor, its noise spectrum will emphasize specific frequencies. This leads to sound coloration and masking of details.

I suggest to use home made non-inductive wire wound resistors with low stray capacitance like maxlorenz did.

If you want to use off-the-shelf non-inductive wire wound resistors you could try Rhopoint or Neohm.
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Old 11th January 2012, 12:45 PM   #4136
galeb is offline galeb  Spain
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Anyway, has anyone ever tried Takman carbon series?.....
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Old 11th January 2012, 04:30 PM   #4137
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Hi,

Quote:
Originally Posted by -ecdesigns- View Post
If you want to use off-the-shelf non-inductive wire wound resistors you could try Rhopoint or Neohm.
I would second Rohpoint, Neohm less. Rohpoint are truely excellent. For my first TDA1541 Non-OS DAC (in 98) I handmade bifilar wound Non-inductive 25 Ohm resistors. In susequent builds I compared to Rohpoint (which I have used extensively and found no reason to handwind resistors.

In my commercial designs we use a specfic type of SMD resistors after auditioning tons. Some SMD resistors are really bad, some are so-so and some are most excellent, though no patch for a Rohpoint Squaristor GR102.

Ciao T
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Old 13th January 2012, 07:14 AM   #4138
dady is offline dady  Argentina
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Default Where can i get the wire for build the honeycomb resistor?

Quote:
Originally Posted by maxlorenz View Post
Hi guys,

If the gurú says "build your own honeycomb resistors because they are better", then that's what I do.

https://picasaweb.google.com/lh/phot...eat=directlink

https://picasaweb.google.com/lh/phot...eat=directlink

Cheers,
M.
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Old 13th January 2012, 08:23 AM   #4139
ryanj is offline ryanj  Australia
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Dady,

Ive got heaps of wire, have a read here: ENAMELED CuNi44 0.1mm diameter (Constantan, Isotan) Resistance wire

Ryan
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Old 13th January 2012, 11:52 AM   #4140
galeb is offline galeb  Spain
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Isn't 200 mts of wire too much for the very weak current output signal of the DAC?, I'm not sure to test the honeycomb resistor.......
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