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Old 15th August 2008, 05:27 AM   #121
Cappy is offline Cappy  United States
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Randy,

Right. It depends on location. Depends on resistor type. Depends on TSR (taste-system-room).

Different cooking recipes will respond to the sage herb differently, for example.

Like most things in high-end audio this is quite the controversial subject. Some people believe that resistors don't make a difference and others just look for low noise resistors and others believe any differences are subtle. Viva La Difference.

Here is a stream of consciousness take on a few resistor types -- from the point of view that sage can taste different in different recipes, but also that there is a particular sage taste which will usually come through. In my toying around with resistors, I've referenced against a powerful measurement tool I have access to, my live-in audio control subject, Miranda.

Tantalums are one of my favorites. They have a nice clear midrange, are dynamic, good bass, non-glarey shiny treble. In larger doses the midrange can start sounding a bit unnatural and the highs a touch closed in and too shiny/unnatural.

Rikens are warmish and laid back with decent treble. They can sound a bit fuzzy. Too many (and that may include just one) can be boring sounding in tube circuits, imo. Maybe a better match with solid state. Mixing the Rikens with metal films might be a good match in your tube amp.

Caddocks can be very good. I've heard them be a little bright and they can also sound "flat" with reduced soundstage depth. A good match with tants.

Metal films can sound overly bright in some positions but they have good detail, air, bass. I've also heard them where they aren't bright at all. Caddocks are metal film (or similar, I think?) but they don't sound like other metal films I've heard.

I'm not familiar enough with the characteristics of Mills wirewounds to say much. They replaced metal film resistors in my PCM63 Dac and I don't have any impulse to change them out. I also use them in a speaker crossover. Them seem balanced without glare. People seem to like them on tube anodes and power supplies. Success with them as with the others probably depends on, as you say, "where you put them".

I tried Vishay S102 nudes in my phono stage as load resistors. They sounded interesting with a kind of ethereal treble but overall a bit lightweight. Some people like them in serial signal applications like volume controls. I'd like to play around with them more, in very small doses, but they are expensive. I'm guessing a 1:3 proportion with Shinkohs might sound good. But some new recipes just taste bad.

I think mixing resistor types in a circuit is useful as it can balance colorations. Mixing for one circuit element is just an extension of that.

************

I've soldered in the parts of the Aikido PCB which control the lines for the 5687 vs. other 9 pin types since I'm going to stick with the 5687 in position two. I also soldered in the Mundorf ZN tinfoil coupling caps. Those changes got rid of 14 alligator clips.

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Old 15th August 2008, 08:06 PM   #122
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Thanks for the info Cappy.

I believe that resistors have sound, and different kinds make a difference.

I will probably keep my current plan, but as time/money allows, try some other things in the future. Tantalum resistors look pretty pricey, but I would like to try them once I get everything working right.

Randy
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Old 17th August 2008, 03:47 PM   #123
boudy is offline boudy  United States
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Default Balanced Aikido for Buffalo DAC

Hey,

I'm in the process of assembling a pair of balanced Aikido boards and PSU to use with the Buffalo DAC.

Here is my PSU design, it leverages my existing stock of parts. I'd appreciate any comments.

The transformer is an Antek T150.

The rectifier diodes are UF1007.

Thanks.
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Old 17th August 2008, 05:31 PM   #124
Cappy is offline Cappy  United States
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Hi Boudy,

Good news about the design: low ripple and pretty snappy response.

Bad news: "Lord of the Rings".

More bad news: Since each current tap has differing levels of filtering, with the I2 tap having an additional LC cell, each side of your balanced Aikido will sound different.

You are showing the initial response of your power supply in the first second or so. What you want to do is wait until the supply settles down -- in the first few seconds things are just coming up -- caps are getting charged, etc. The "reporting delay" box allows one to get out of the startup window.

The PSUD chart below shows the ringing of the I2 current tap with a 10% change in current demand. It should be a smooth response but it has a whole lot of ringing.

I'll post more later when I have more time, with some suggestions. You have a lot of parts to work with so I bet you will be able to come up with something good. Also, if you use alligator clips you will be able to move things around to see how changes effect the sound.

I didn't realize that PSUD II supported multiple current taps. That is useful, thanks for the demonstration of that cool feature.
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Old 17th August 2008, 05:38 PM   #125
boudy is offline boudy  United States
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Default Thanks for the feedback

Hi Cappy,

The model doesn't accurately depict the planned implementation, the second LC stages would be in parallel, not in series. I don't know of a way to do a parallel model in PSUD.

Did you implement a step in the current source to generate that signal?

Nice psud file name! ;-)

Back to the drawing board...

-Eric
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Old 17th August 2008, 05:44 PM   #126
Cappy is offline Cappy  United States
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Yes,

Check stepped load box.

Value1: 50m
Value2: 45m
After: 5 seconds

-- Bill
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Old 17th August 2008, 05:56 PM   #127
Cappy is offline Cappy  United States
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Yeah, I don't know how to do the parallel supply either. Probably better just to take out that last leg since it is not representative, and put in 100mA for the first current tap.

One problem with parallel legs and LCLC filters is that it becomes a much more complex system, more prone to ringing and resonances. And we don't have psud to help us. Particularly if lowish levels of series resistance is used for damping.

I decided to punt trying a parallel supply. Also, mono vs. stereo supplies is another controversial subject. Some people with a lot of experience believe stereo supplies actually sound better. And that it's better to have "stacked" supplies with a single stereo supply per stage instead of two mono supplies. I'm not suggesting a stacked supply and I don't think it would even work with the Aikido, but I think a pure stereo supply like i am using is worth trying. But with alligator clips you could try different approaches yourself and draw your own conclusions since you have a lot of parts.

Another thing you could try is make the last parallel legs RC cells. This would help with damping and give some isolation between the sides. I don't know how it would sound. So far I'm finding not using too much series resistance in the supply is better. But as usual, there are different schools of thought on this.

-- Bill
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Old 17th August 2008, 06:00 PM   #128
boudy is offline boudy  United States
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Hey Cappy,

I dropped the current to 45 ma after 5 seconds in the last stage and closely matched your result.

Reducing the first capacitor to 10uF seems to eliminate the ringing.

-Eric
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Old 17th August 2008, 06:04 PM   #129
boudy is offline boudy  United States
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Default Simultaneous posting!

Hey,

Yeah I've been considering a separate supply per channel, that would also provide considerable slack in the heater current supply. But another transformer and 5H choke won't fit in the chassis that I have, d'oh!

I will contemplate this on the tree of woe.
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Old 17th August 2008, 06:11 PM   #130
Cappy is offline Cappy  United States
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Actually I was proposing just a single supply for everything, not two, like I am doing it.

Lowering the first cap is moving in the right direction. In general you want your cap values to increase as you move from left to right and inductance values to decrease. And not too high a value for the first cap, imo.

I still see some mild ringing with 10 uF though. The B+ voltage is quite a bit lower too.
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