Very nice.
What PCBs are you using?
Still pondering wether I will make me an Aleph pre or buy me a secondhand X2.5 one day
What PCBs are you using?
Still pondering wether I will make me an Aleph pre or buy me a secondhand X2.5 one day
Member
Joined 2002
19" housing with a sanded aluminium surface and steinless steel buttons will be nice, but this is a long way...
thx
Adam
thx
Adam
I listened so far with direct connection CD to my power amp (selfmade like Thel), see my homepage http://www.acaudio.de (under construction). I will compare this with another preamps when the relay volume control works. With headphones sounds smooth and sweetly but these have only 75 ohms impedance.
thx
Adam
thx
Adam
problem with relay volume control
Hi,
the relay volume control like aleph p1.0 (with adc0804) works. 🙂
Problem:
between step 32 (relay 1-5 on, relay 6 off) and 33 (relay 6 on, 1-5 off) gives it pop noise. Only with signal.
anybody an idea? 😕
thx
adam
Hi,
the relay volume control like aleph p1.0 (with adc0804) works. 🙂
Problem:
between step 32 (relay 1-5 on, relay 6 off) and 33 (relay 6 on, 1-5 off) gives it pop noise. Only with signal.
anybody an idea? 😕
thx
adam
You have already found the reason for the problem:
This happens when all te relays are switching at once - this generates a very short "level step".
One proven method to get rid of that requires the presence of a "mute relay" on the output and some additional circuitry (microcontroller to be preferred): just switch the mute relay on just before the volume control makes "the evil step". If you play a little with the delay times, you might get this solution working without audible effects.
This happens when all te relays are switching at once - this generates a very short "level step".
One proven method to get rid of that requires the presence of a "mute relay" on the output and some additional circuitry (microcontroller to be preferred): just switch the mute relay on just before the volume control makes "the evil step". If you play a little with the delay times, you might get this solution working without audible effects.
Hello Holger,
thanks for your replay. How is your new LP?
I would like to do this without microcontroller.
I have already by parallel connection of a 1k resistor at the exit of the circuit a clear improvement reached. The gain is a little lower, but it works good.
I like this Aleph sound, i have today removed the input capacitor from the power amp , it sounds very good with much more detail and dry bass...
Now i need a housing.
greetings
Adam
thanks for your replay. How is your new LP?
I would like to do this without microcontroller.
I have already by parallel connection of a 1k resistor at the exit of the circuit a clear improvement reached. The gain is a little lower, but it works good.
I like this Aleph sound, i have today removed the input capacitor from the power amp , it sounds very good with much more detail and dry bass...
Now i need a housing.
greetings
Adam
Attachments
Files
I uploaded the layout an my website.
For first the pre- and supply pcb.
http://www.acaudio.de/aleph_p17_supply_bottom.pdf
http://www.acaudio.de/aleph_p17_supply_top.pdf
http://www.acaudio.de/aleph_p17_bottom
http://www.acaudio.de/aleph_p17_top.pdf
http://www.acaudio.de/aleph_p17_overview.pdf
http://www.acaudio.de/aleph_p17_supply_overview.pdf
Critical comments are welcome.
thx
Adam
I uploaded the layout an my website.
For first the pre- and supply pcb.
http://www.acaudio.de/aleph_p17_supply_bottom.pdf
http://www.acaudio.de/aleph_p17_supply_top.pdf
http://www.acaudio.de/aleph_p17_bottom
http://www.acaudio.de/aleph_p17_top.pdf
http://www.acaudio.de/aleph_p17_overview.pdf
http://www.acaudio.de/aleph_p17_supply_overview.pdf
Critical comments are welcome.
thx
Adam
Great looking AP!
Btw - the "bottom" (3rd one) pdf is not working (at least in my case
)
How exactely did you do your PCB?? Are they milled?
Btw - your amplifier - how hot does it get - and do you find the copper plates with transistors mounted on it as a good solution or not??
Btw - the "bottom" (3rd one) pdf is not working (at least in my case

How exactely did you do your PCB?? Are they milled?
Btw - your amplifier - how hot does it get - and do you find the copper plates with transistors mounted on it as a good solution or not??
Re: problem with relay volume control
try with elco in paralel with some relay coil;
that will give ya small delay
mebbe it will work

acaudio said:Hi,
the relay volume control like aleph p1.0 (with adc0804) works. 🙂
Problem:
between step 32 (relay 1-5 on, relay 6 off) and 33 (relay 6 on, 1-5 off) gives it pop noise. Only with signal.
anybody an idea? 😕
thx
adam
try with elco in paralel with some relay coil;
that will give ya small delay
mebbe it will work

Stabist said:Great looking AP!
Btw - the "bottom" (3rd one) pdf is not working (at least in my case)
How exactely did you do your PCB?? Are they milled?
Btw - your amplifier - how hot does it get - and do you find the copper plates with transistors mounted on it as a good solution or not??
uups 😉
http://www.acaudio.de/aleph_p17_bottom.pdf
/Adam
Stabist said:...How exactely did you do your PCB?? Are they milled?
Btw - your amplifier - how hot does it get - and do you find the copper plates with transistors mounted on it as a good solution or not?? [/B]
The pcbs are Bungard FR4 singlesided.
The photoplots are printed on transparece paper with laser printer. Exposed with UV light and developed with NaOH. Pcbs is normally atched at 50°C witch sodium-per-sulfate .Then drilled and afterwards still times full-laminar exposed and developed with NaOH.
For last soldermask painted (Contact).
The Fets runs hot, aprox. 70°C without heatsinking, 65° with. With copperplate these are optimal thermal coupled. A simple thermal coupling in pair isn´t available then this layout is nearly point-symmetric, so are all coupled, both channels an one copper plate. and this looks pretty. I like copper then this is nearly double thermal conductive as aluminium.
sorry for my bad english

/adam
Re: Re: problem with relay volume control
This works GOOD!
Danke Holger!
The relay coil has 320OHM/2=160Ohm -> For delay aprox.0,1s you need a capacitor ~625µF and have almost short by off->on switsching.
I added a 1µ capacitor at basis, and this works pretty.
The resistor parallel to output is now removed.
thx
Adam
HBarske said:...If you play a little with the delay times, you might get this solution working without audible effects. [/B]
This works GOOD!
Danke Holger!
choky said:
...try with elco in paralel with some relay coil;
that will give ya small delay
mebbe it will work
![]()
The relay coil has 320OHM/2=160Ohm -> For delay aprox.0,1s you need a capacitor ~625µF and have almost short by off->on switsching.
I added a 1µ capacitor at basis, and this works pretty.
The resistor parallel to output is now removed.
thx
Adam
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