Ive begun the process of crafting a preamp following the fine design of the pass aleph p. the idea of building m own stereo was never something id ever considered possible except in my dreams. Thanks to this community and the generosity of nelson pass, ive been able to slowly learn bits and pieces about audio component design structure and function.
After finishing the pass labs pearl 2, designed by wayne at pass labs, and falling head over heels in love with records, i couldn't help but want to build a matching preamp/control deck to pair with it and my turntable.
This forum is to discuss the challenges and success in building a copy of the aleph p for personal enjoyment and education.
After finishing the pass labs pearl 2, designed by wayne at pass labs, and falling head over heels in love with records, i couldn't help but want to build a matching preamp/control deck to pair with it and my turntable.
This forum is to discuss the challenges and success in building a copy of the aleph p for personal enjoyment and education.
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Just about finished the attenuator boards, relay driver and control deck. My veteran preamp boards are almost complete. What a tight fit! Vishay dale RN60s and RN65s are great but the cmf would have fit better on these boards.
Ive selected the 250v wima mkp4 polypropylene capacitors for input and output, as im under the impression that they sonically may outperform polyester type caps or electrolytics. They dont fit on veterans boards at all, but a little creative mounting and point to point wiring should be just fine.
Im building a loopbreaker and ground protection with a 35 amp bridge rectifier just as i did with the power supply for the pearl2, and housing the power supply seperately... But im not sure how ill manage the connection yet. 3 distinct power supplies and a ground will require a good safe connection... Im considering dsub or 8pole speakon connectors... Any thoughts? ...fitting ti all in one box wont be easy and besides, id like to stack my control unit on my pearl2 and hence need to avoid the transformer hum.
Im selected paired DPDT omron low signal relays for input switching, and wiring the coil voltage to a rotary switch mounted to the front panel. Im hoping this will work and allow quiet input switching...
Ive selected the 250v wima mkp4 polypropylene capacitors for input and output, as im under the impression that they sonically may outperform polyester type caps or electrolytics. They dont fit on veterans boards at all, but a little creative mounting and point to point wiring should be just fine.
Im building a loopbreaker and ground protection with a 35 amp bridge rectifier just as i did with the power supply for the pearl2, and housing the power supply seperately... But im not sure how ill manage the connection yet. 3 distinct power supplies and a ground will require a good safe connection... Im considering dsub or 8pole speakon connectors... Any thoughts? ...fitting ti all in one box wont be easy and besides, id like to stack my control unit on my pearl2 and hence need to avoid the transformer hum.
Im selected paired DPDT omron low signal relays for input switching, and wiring the coil voltage to a rotary switch mounted to the front panel. Im hoping this will work and allow quiet input switching...
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Well, there is the Aleph P1.0, and the Aleph P1.7, and the Balanced Zen Line Stage (aka BOSOZ) and countless CCSXYZ versions. I have played with all the Pass versions. The one I found most worth trying again is suppoorted by this statement from the 1997 article, "Balenced Zen Line Stage":
"This is a particularly good sounding circuit, and I think it sounds
significantly better than the Bride of Zen, although I would be hard
pressed to explain why. It seems more liquid and has greater depth,
while BOZ is a bit dry by comparison. It might be distortion cancellation
in the balanced circuit, or it might be the greater dynamic range afforded
by quieter balanced operation and higher output swing. As always, I
encourage you to build it and decide for yourself." N.P.
And as many others, I applied more voltage, more Iq, etc. etc. But now, we have the Semisouth R550 device and I'm ready to do it again...
In the true Pass Zen spirit, why would you want more?
"This is a particularly good sounding circuit, and I think it sounds
significantly better than the Bride of Zen, although I would be hard
pressed to explain why. It seems more liquid and has greater depth,
while BOZ is a bit dry by comparison. It might be distortion cancellation
in the balanced circuit, or it might be the greater dynamic range afforded
by quieter balanced operation and higher output swing. As always, I
encourage you to build it and decide for yourself." N.P.
And as many others, I applied more voltage, more Iq, etc. etc. But now, we have the Semisouth R550 device and I'm ready to do it again...
In the true Pass Zen spirit, why would you want more?
formosawest:
i did almost the same thing. you shouldnt have any issues with the relays, i didnt.
i did a xono and aleph P1.7 with a seprate power.
i used 8 pole mill style conectors for mine. both duel mono.
you dont need high current. so prettymuch anything will work. i tend to like heavyduty solid built but nothing fancy.
i did almost the same thing. you shouldnt have any issues with the relays, i didnt.
i did a xono and aleph P1.7 with a seprate power.
i used 8 pole mill style conectors for mine. both duel mono.
you dont need high current. so prettymuch anything will work. i tend to like heavyduty solid built but nothing fancy.
Thanks sakellogg! Im glad to hear it worked out for you. Im thinking a dual deck switch so i can run a set of led input indicators as well. ... What do you think?
I kinda wish my pearl had balanced output so o could take advantage of the common mode noise rejection of the balanced type circuit for my record playback.
dual deck will work for sure. could also put the led's and resistors in paralel off the coils of the relay.
i dont know if the balanced output makes it sound any better or not. but it was there so away i went. i wouldnt loose sleep over it for sure.
what did you use for vol control.
back emf might fry the led's. i know the relays at work are huge so maybe small ones wont matter?
maybe someone smarter than me will know.
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relay based attenuator pretty much what you have. ive got to replace the pot on it. its getting flakey.
i put in relays for the db selection too. so basic 3 knob system.
youll like it. very nice sounding.
only thing i dont like is now i know how many crap records i have. if your recording sucks youll know it. but if its a gem youl love it.
i put in relays for the db selection too. so basic 3 knob system.
youll like it. very nice sounding.
only thing i dont like is now i know how many crap records i have. if your recording sucks youll know it. but if its a gem youl love it.
Db selection?
Question for you.... The 2k multi turn variable resistors on the Center of the board... Are those for setting gain?
Since this board is running on + dc voltage only i wont need to worry about dc offset will i?
I take it the little keyboard switches are for gain level selection.
Question for you.... The 2k multi turn variable resistors on the Center of the board... Are those for setting gain?
Since this board is running on + dc voltage only i wont need to worry about dc offset will i?
I take it the little keyboard switches are for gain level selection.
2k pots... yes, they can. i used them to get the output the same for both chan.
it dosent just run on positive. do you mean its not bypolar?
but no that isnt why you dont have to worry. if i remember right..... the 30uf on each leg of the output is why no worrys on offset.
remember to dc caps look like a open, but let ac go through.
keyboards yes you are right. those are what i call db selection.
i did them with relays too.
it dosent just run on positive. do you mean its not bypolar?
but no that isnt why you dont have to worry. if i remember right..... the 30uf on each leg of the output is why no worrys on offset.
remember to dc caps look like a open, but let ac go through.
keyboards yes you are right. those are what i call db selection.
i did them with relays too.
Thats a Good idea doing then db selection like that.. Saves cracking the case open to make the selection.. when running a phono stage sometimes a little extra gain is great, but not otherwise needed/wanted for other modern high gain sources. Any recollection what relays used.. Im guessing you just wired it up off board?... Hmm ill have to think about it how do do that to give the three settings. Two relays per channel (one for each little keyboard key) and one panel mounted switch?
Im thinking of adding a 12 volt trigger out from the power switch to allow me to trigger future components on/off with the alephP
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i did it as a daughter board off of the main. i used some mini signal relays. i dont remember. ill take dome pics tomarrow.
but 2,2pole per chan. is what i think i did. funny thing is you make a 3 point switch. 1 pole picks one relay. next pole dosent do anything... next picks the other relay. it was hard to wrap my mind around a pole on the switch just for the click so to speak. kinda funny to me. but like you said its nice for a l.p. guy.
i haddent thought of a trigger out....which is funny cause i built it into my alephs....woops!
im gunna have to add that to it! thanks for reminding me.
but 2,2pole per chan. is what i think i did. funny thing is you make a 3 point switch. 1 pole picks one relay. next pole dosent do anything... next picks the other relay. it was hard to wrap my mind around a pole on the switch just for the click so to speak. kinda funny to me. but like you said its nice for a l.p. guy.
i haddent thought of a trigger out....which is funny cause i built it into my alephs....woops!
im gunna have to add that to it! thanks for reminding me.
Im really curious about building a pair of balanced aleph x mono block's at about 100watts. Though for some reason that project appears to be a bigger challenge to me mentally than the pearl or the ap1.7. Seems the amps are expensive to uild and everyone here seems to be using scopes to get them right.... And i dont have a scope, nor do i know how to use one. ... But boy woul dlike to build a pair.
Did you ever build the xbosoz? I wonder how the ap1.7 compares sound wise.
Did you ever build the xbosoz? I wonder how the ap1.7 compares sound wise.
About the 2k pot. Dpes gain increase as the level of resistance increases, or does it increase as the level of resistance decreases? Before i soldered them in i matched them both to 2.00k and im wondering if that will be its maximum gain or minimum gain (for any given keyboard switch setting)
