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Old 7th March 2006, 07:24 PM   #41
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Quote:
Originally posted by KT

How about buffer unit before the TVC? How does that compare to the buffer before the resistor attenuator?

Does the buffer give some drive and bite to the TVC sound that it was missing?
I tried the TVC with a buffer but I was still getting more resolution "edge" with resistor based attenuator. However, that may depend on particular systems and personal preference. I cannot say that one or the other is definitely better.
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Old 16th March 2006, 11:32 PM   #42
SamL is offline SamL  New Zealand
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According to some of the folks in Headwize, Shunted Linear Pots have varying impedance to the source which wll affect the sound quality.
http://tangentsoft.net/audio/atten.html

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Old 17th March 2006, 01:36 PM   #43
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Thumbs up ALEPH30 and ATTENUATOR

Dear Peter:

Congratulations for your work.

I purchased from you a DAC, 1 Premium LM3875, 1 Premium LM4780 Kits and from your partner, George a PRE T-1.

Please can you let me know if you still have Aleph30 boards in stock, and what about the selected Mosfets.
Wich is the 22KMF power supply capacitors Brand and type you recomend.

Regarding the Attenuator proyect I am interested to purchase one, can you tell me what do you thimk to offer and wich resistors Brand and type you preffer ?

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Old 17th March 2006, 02:32 PM   #44
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Hi Georgio,

I will reply later in more detail to your post, however, I could not resist commenting right now on the quote below:

Quote:
Originally posted by SamL
According to some of the folks in Headwize, Shunted Linear Pots have varying impedance to the source which wll affect the sound quality.
Thanks for an interesting link. The article didn't mention anything about affecting sound quality, it only comments on source's performance, which is not neccessarily the same:

"Another problem with this technique is that a shunted pot presents a varying impedance to the source as you turn the knob. A pot without a shunt resistor presents a constant impedance to the source, so the source's performance doesn't change as you turn the knob."

So, success with implementing such attenuator will depend on the source itself, but with well designed outputs, it shouldn't present major problems. My source has high current drive capability with 6 ohm output resistance.

I'm using series 10k resistor at the amp's input (fixed) so input impedance never goes below that value. I don't need wide range of volume setting for normal listening, and so far, I only needed shunt resistors values between 402R and 3.48K. That varies input resistance between 10402R and 13480R. I don't think it affect any performance.

I would not recommend linear pot for such application: only a switch with discreet resistors.

After saying that, the attenuator board I'm working on, has constant input impedance that does not change through all 130 steps.
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Old 17th March 2006, 08:41 PM   #45
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Thumbs up ALEPH 30 and ATTENUATOR

Dear Peter,

You answer another post, please read again mine.

Thanks and congratulations again.
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Old 17th March 2006, 10:50 PM   #46
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Default Re: ALEPH30 and ATTENUATOR

Quote:
Originally posted by A. J. Gandulfo
Please can you let me know if you still have Aleph30 boards in stock, and what about the selected Mosfets.
Wich is the 22KMF power supply capacitors Brand and type you recomend.

Regarding the Attenuator proyect I am interested to purchase one, can you tell me what do you thimk to offer and wich resistors Brand and type you preffer ?
Thanks for appreciating my products

I will have more Aleph30 boards next week, as I ordered new batch. I also have one more set of output mosfets left.

Regarding 22,000uF caps I have some Siemens Sikorel, but those would be quite expensive. Another good brand could be Nichicon Super Through from Percy Audio.

The attenuator still needs programming to be done. The resistors I like here, are nude Vishays from Texas Components in series position, and with GC amps, Caddocks MK132 in shunt position.
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Old 18th March 2006, 12:30 AM   #47
XELB is offline XELB  Portugal
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Nice work Peter

I think you read people mind, I am just needing something like that
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Old 18th March 2006, 09:55 AM   #48
SamL is offline SamL  New Zealand
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Hi Peter,

Thanks for your replay.

Quote:
Originally posted by Peter Daniel

After saying that, the attenuator board I'm working on, has constant input impedance that does not change through all 130 steps.
You got me very interested now. Looking forward to the product release.

Quote:
Originally posted by Peter Daniel

I'm using series 10k resistor at the amp's input (fixed) so input impedance never goes below that value.
Is it possible to have 25K resistor at the amp input? This will work better with my not so granty source like tuner and video.

Have fun,
Sam
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Old 3rd April 2006, 09:36 PM   #49
jleaman is offline jleaman  Belgium
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I to are also interested. Has there been any more progress on this ?
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Old 3rd April 2006, 09:48 PM   #50
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As mentioned in the other thread, the control board has been already fabriacated and my partner in that project, Veteran, is working on programming.

The input resistance can be set to any value.
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