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(one more) ALEPH P 1.7 clone

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#444
Tarasque, does the airflow influence the sound? Teake
Click to expand...

Yes...I think so.

The Id/Ugs function is very sensitive for temperature.
Especially when one side if the PCB has a stronger draft as the other side, there will be a shift in ballance. As this topology needs strong symetry for optimum performance, I would not be surprised if it was audible. Also as the FET gets hotter, the change in temperature will be larger when there is airflow.

Marcel.
 
#446
Economical approache to volume control

Open for discussion:
-I don´t like to use a uP
-I don´t like to use a 8-deck rotary switch for balanced output
volume control
-I like to use the least amount of relais
-I like to use the least amount of resistors

What do we need:
- a single deck 16 or 24 position rotary switch
- a diode matrix
- someone who comes up with an old but still buyable TTL IC
replacing the diodes
- 4 resp. 5 relays (x2 = stereo, x4 = balanced stereo)
- 4 resp. 5 resistors (x2 = stereo, x4 = balanced stereo)
- someone who comes up witch a neat program to calculate
the resistors, switched in parallel by the relais for a nice
log. curve.
 

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#448
- 4 resp. 5 relays (x2 = stereo, x4 = balanced stereo)
Click to expand...

You are making a mistake here. If you want to use digital bases of your relais control, you are bound to resistor values doubling for each bit.

If you want -60dB maximum attenuation and about 2dB per step, you would need 8 relais to compensate for the lineair resistor network and required logaritmic behavior.

At a pot impedance of 10K and minimum 32 steps starting at -60dB, you are looking to implement a lookup table to reduce the 32 wanted value out of the possible 256 (8 bit)

I have tested this and it works fine. However a PIC interface to the relais would be nice.
An other option is to program the bit values in a rom and use drive the address bits from a counter and use the data bits to drive the relais.

For those looking for small relais with 2xom contacts, I still have plenty left. let me know.
 
#451
peterpan188 said:
Hey guys,

I missed the last run, so I emailed veteran asking if he has extra boards. He mentioned we can have another board GB. So is there interest here, or I should open up another thread for interest check?

Regard,
Peter
Click to expand...

I'am interested 😀

I think it's beter to open another tread - like, second run on Aleph P1.7 boards
 
#454
Hi Teake,

My boards are fully assembled and working properly. I'm currently building the case, power supply and building the relay driven ballanced volume control and input selection,

I'm using Holco resistors in the volume control. I bought the moduled from Apox controls in the US (with remote control)

I still would be interested to implement the original pass relay attenuator driven from a PIC. I have no clou how to make a program and how to program a PIC. I would appreciate some help in that respect.
 
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