Pass Aleph P1.7 Help needed

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Hi all,

i am currently building an Aleph p 1.7 clone.
PCB comes from

Test show that the amplification is not working properly:
With an input voltage of 450mV I get 1.05 V output max.
I tried all Input Switch Positions.
The 9610 are running very hot (85 degree C).
Does anyone who already built an Aleph P 1.7 have the voltages over Mosfeet and Bipolar Transistors and can send these value to me.

Any help is highly appreciated.

Thanks and All the best


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Joined 2004
Do you want my PCB

Give me your PCb design or post it here.

I'll be compare & check PCB line. You may be get a wrong design of PCB.

Now I use AlephP1.7 ,too.

It's sound nice with Evox capacitor 12uF*8/63V.I'll be compare with Panasonic FC series soon.

If you want my PCB's design & bias test point can email me for send it.



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If you are using an attenuator or potentiometer on the output please disconnect it then remeasure the gain. Remember that the output is 1/2 if your are using the single ended input. If you are using single ended input remember to short the negative input to ground. Also remember that the internal attenuator switches need jumpers in position 1,2,7,8 and 3,4,5,6 should be open for zero dB input attenuation.
jh6you said:
If the voltage measures about 0.60-0.7 accross R44/55/59/70 and about 30V at the drains of 9610s. Nothing is wrong.

Mayby Nesson Pass is wrong!!! :bigeyes:


Thanks for your help. This is exactly what I meassure. I have approx. 30 V at the 9610 Drain and 60 V at the 9610 Source.
But I can not see an amplification. I used a sine wave 450 mv at the input (single ended) and messured max. 1040 mv at the output (single ended) with the highest amplification set at the input switches.
Why are my 9610s running so hot (85 degree C) ?
I definetly appreciate all ideas !
kilowattski said:
The switches do not set input impedance they set input attenuation. If you download the Aleph P 1.7 users manual it tells you how to set the switches.

Thanks kilowattski,

this is exactly what I meant. Pls. correct me when I am wrong. As think and meassuered that the input impedance is also affected by these switches. With max. amplifaction set at these switches I only get appox. 1 Volt out of 450 mV.


Wrong, Wrong, Wrong. SDF please look at page 2 of the service manual. Nelson outlines the setting of the switches for various attenuator settings.

The input pad settings are as follows (only 3 settings)

1.3 dB......3,4 5,6 on
9.7 dB......ALL OFF
15 dB.......1,2 7,8 on

Nelson please forgive me for coping the above sentence from your service manual.
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.