Gain in Aleph P 1.7

bbakota2000 · 7th May 2004, 10:17 PM

Hi,
I have a question regarding Aleph P gain. In the position of 2K pot on the original schematics I want to put a resistor, so I can achieve max gain (22dB balanced/ 16 dB unbalanced). Which resistor value should I use? I will use Aleph P together with an Aleph 5. I will put stepped attenuator on the output. Thanks for advise!

Nelson Pass · 8th May 2004, 01:20 AM

You can put in any resistor you like. For 22 dB, you want to
look at the 100 to 200 ohm range.

kilowattski · 8th May 2004, 02:58 AM

Nelson,

My Aleph P 1.7 is coming along nicely also. It seems there has been a rash of Aleph P 1.7's being built lately. I would like to include a pair of Gain Controls on the front panel just like the genuine article. Can I use a linear taper pot? Would you recommend a high quality pot like an Alps? I have seen alot of press about conductive plastic pots. They are claimed to be very long lasting. Would that be suitable, not that it would get changed often?

bbakota2000 · 8th May 2004, 11:39 AM

I remember reading somewhere that I shouldn't go below 800ohms, and the max is around 1.5K. I think it was related to Aleph P.
Is that feedback resistor?

jh6you · 8th May 2004, 03:28 PM

Quote:

Originally posted by kilowattski

Can I use a linear taper pot?

I would try to use 6-step rotary switch of good guality with five 400 ohm registers--i.e. to get 0, 400, 800, 1.2K, 1.6K and 2K at each step. I approximate that these register values will give you 22dB, 14dB, 10dB, 7 dB, 5dB and 3dB gains. Or, you could use different register values.

Good luck.

kilowattski · 9th May 2004, 01:27 AM

Thank you!

tomchaoda · 17th May 2004, 02:04 PM

How do you achieve the maximum 22dB (balanced) from Aleph P1.7? by lowering the 2K VR or by close the sw 1.1 & 1.2?

What's the formula of this gain?

Thomas

jh6you · 17th May 2004, 02:26 PM

I assume that the gain is approximately X = (R53//R56)/(R51+R66+2K pot set value)--i.e. 20 x log(X) dB.

Klaus · 17th May 2004, 02:35 PM

Quote:

Originally posted by jh6you
I assume that the gain is approximately X = (R53//R56)/(R51+R66+2K pot set value)--i.e. 20 x log(X) dB.

Hi,

I think, we also need to consider R49 - it lays in parallel to R53//R56 for AC.

regards

Klaus

bbakota2000 · 17th May 2004, 03:09 PM

I tried to use this formula with 820 R value for a fixed resistor instead of a pot, but I got a value of 0.00206 for X. When I calculate the 20 x log(X) it turns out to be -53.72dB. What does this value mean?

7th May 2004, 10:17 PM	#1
bbakota2000 diyAudio Member Join Date: Jan 2004 Location: Croatia	Gain in Aleph P 1.7 Hi, I have a question regarding Aleph P gain. In the position of 2K pot on the original schematics I want to put a resistor, so I can achieve max gain (22dB balanced/ 16 dB unbalanced). Which resistor value should I use? I will use Aleph P together with an Aleph 5. I will put stepped attenuator on the output. Thanks for advise!

8th May 2004, 02:58 AM	#3
kilowattski diyAudio Member Join Date: Aug 2003 Location: Long Island, New York	Nelson, My Aleph P 1.7 is coming along nicely also. It seems there has been a rash of Aleph P 1.7's being built lately. I would like to include a pair of Gain Controls on the front panel just like the genuine article. Can I use a linear taper pot? Would you recommend a high quality pot like an Alps? I have seen alot of press about conductive plastic pots. They are claimed to be very long lasting. Would that be suitable, not that it would get changed often? __________________ ----------------------------------------------- Kilowattski

9th May 2004, 01:27 AM	#6
kilowattski diyAudio Member Join Date: Aug 2003 Location: Long Island, New York	Thank you! __________________ ----------------------------------------------- Kilowattski

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8th May 2004, 01:20 AM	#2
Nelson Pass The one and only Join Date: Mar 2001	You can put in any resistor you like. For 22 dB, you want to look at the 100 to 200 ohm range.

8th May 2004, 11:39 AM	#4
bbakota2000 diyAudio Member Join Date: Jan 2004 Location: Croatia	I remember reading somewhere that I shouldn't go below 800ohms, and the max is around 1.5K. I think it was related to Aleph P. Is that feedback resistor?

17th May 2004, 02:04 PM	#7
tomchaoda diyAudio Member Join Date: Sep 2003 Location: New Jersey	How do you achieve the maximum 22dB (balanced) from Aleph P1.7? by lowering the 2K VR or by close the sw 1.1 & 1.2? What's the formula of this gain? Thomas

17th May 2004, 02:26 PM	#8
jh6you Account Disabled Join Date: Aug 2002 Location: Near to the Pacific Ocean	I assume that the gain is approximately X = (R53//R56)/(R51+R66+2K pot set value)--i.e. 20 x log(X) dB.

17th May 2004, 03:09 PM	#10
bbakota2000 diyAudio Member Join Date: Jan 2004 Location: Croatia	I tried to use this formula with 820 R value for a fixed resistor instead of a pot, but I got a value of 0.00206 for X. When I calculate the 20 x log(X) it turns out to be -53.72dB. What does this value mean?

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