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(one more) ALEPH P 1.7 clone

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#242
Tarasque:

I need matched MOSFETs for two sets of Veteran's Aleph P 1.7 PCBs and have no idea what parts are needed to stuff the boards. You'll be doing me a huge favor if you can supply any matched parts. Just let me know the price including shipping to the U.S. and how you want to be paid.

Regards,
Scott
 
#243
I have recieved the PCB for the Aleph 1.7. However, as I bought two sets of dual mono PCBs I've decided that I want to try to build a really cheap and simple version, just to get it to work basically. To do this I need advice, lots of it. Can anyone recommend a cheap volumecontroll, line selector, inputboard or some input solution (what do I need?) and is there anything I need think about with regards to the output?

With regards to the resistors: the values stated are 22.1 and so on. The closest I have found are 22. Will a small discrepancy from the value matter - if so - where can I get the correct values. Which is preferable: 0.25 or 0.5 w?

What voltage tolerances must the 10uF and 1000uF on the PCB (not PS) manage?

Also I would be interested in mached mosfets for both my dual mono sets.

Sorry for all the questions, but I am quite new to DIY (built a DDDAC and AW-D3 dac before)

Thanks in advance!
 
#244
Hi folkeb,
feel free to put 22 kohm (also 22 ohm where it belongs) resistors instead of 22.1, it doesnt metter. All that is inportant to place as close as possible values on boath sides ( possitive and negative side of preamp) to achive almost the same input inpedance of boath positive and negative side of signal, and CMRR.
For input to ground resistors is OK to place 0.25W resistors, but on the places where flows DC current I would place 0.5 W. I dont understand what do you meen by voltage tolerance for 10 and 1000 uF. Rated voltage I sugest to be 100V, and for 10uF capacitance tolerance to be +/- 5% if you can find them. For 1000 uF elcos use some kind of better quality caps wih +/- 20% capacitance tolerance. I think that it's more important to use some better quality caps (Panasonic or even better) than It's tolerance. Even caps with +50/-10 % tolerance would be just fine.

Volume control is more sensitive question becose of preamp's balanced topology. You can find that this preamp has topology like differential amp (something simillar). What is important is that each side of preamp amplifies just positive or just negative side of input signal. Also it has one parameter called CMRR (common mode rejection ratio). That means it amplifies eny different signal that comes on each side of balanced input, but if the same signal comes on boath (+ and-) inputs (something like noise, or inducted ripple becose of electromagnet field from transformer) it will reject it with almost 60 dB. That value (aprox. 60 dB) is as high as close you can mach input resistors, volume control, and other elements of the circuit (If you put vol. control on the input of preamp). The point is to provide the same amplification of unvanted noise on the boath possitive and negative side of preamp. Also, the same is impotrant becose of separate amplification of possitive and negative part of signal amplitude. If you provide diferent gain of amplification for each side of input signal you will increase distorsion of signal!!! That's all reasons good enough to use relay volume control, multistep rotary switches or similar (with most carefuly mached resistors) and to avoid of use regular poentiometers (even the best ones). For input selector use any kind of relay selector or rotary switch with better quality contacts.
Sorry, I know that all was just theoreticaly but I think it's important to have it in mind when you decide what to do and wich parts to juse. For vol. control look at Veteran's homepage, he has very interesting solutions. Also visit:
http://electronics.dantimax.dk/Kits/index.html I plan to make my version based on original Aleph P1.7 vol control. Dont know will I sucseed😕

Best regards and good luck,
Marko
 
#245
Veteran (and others):

I have read your suggestions that we use Black Gate N series capacitors for the input and output caps on your Aleph P 1.7 PCBs. I have been studying the image files of the preamp board on your website and am curious: is it possible to fit more than two BG N 47uf caps on each channel? In other words, is there any sonic benefit in installing the BG N 47 uf caps at C7, C8, C12 and C13 instead of just at C9 and C11?

Also, are 50V BG N caps suitable at both the input and output on that PCB?

Thanks for suffering a newbie's dumb questions.

Regards,
Scott
 
#247
Quicki Boards Status Question

Hello,

I just discovered this thread. Sorry I have not had time to read the thread beyond the first 60 postings word for word and about 120 postings speed read. The question is is there any chance of getting in on the boards still?

I will read all the thread, but will take me a couple days. Any current status of board ordering, even if more are to be made later is fine by me.


Regards,

John L. Males
Willowdale, Ontario
Canada
07 May 2006 19:46
 
#250
Folks:

I'm a newbie. Can anyone help me identify what "P1" on the preamp PCB is (a Mouser or Digikey reference would be especially helpful)? Similarly, can anyone recommend a part to use for S1A/S1B and S2A/S2B?

I may have other questions in the future, but these are really bothering me.

Thanks,
Scott
 
#251
SRMcGee said:
Folks:

I'm a newbie. Can anyone help me identify what "P1" on the preamp PCB is (a Mouser or Digikey reference would be especially helpful)? Similarly, can anyone recommend a part to use for S1A/S1B and S2A/S2B?

I may have other questions in the future, but these are really bothering me.

Thanks,
Scott
Click to expand...

Some nice pictures showing what to do with switches and P1 (FAQ for gains setting) 😉
http://www.diyzone.net/article.php?sid=395
They made great job drawing them.

In D-K You can find MuRata PV37Y 2kohm multi-turn potentiometer.
 
#260
Also can anyone recommend a attenuator and input selector switch?
Click to expand...
Depends on your budget😀 You could go the "Twisted way" which would be pretty nice🙂 If that is too hmmm, costly? you could go the Elma way (which is almost as costly). An Elma attenuator is pretty nice, I am using one myself, right now😉 If that is still too costly, take a look at an Alps pot🙂 If that is too costly, drop building an Aleph preamp😀 😀 For input selection and a fine preamp like this, I recommend an Elma switch.
Let me know if you want the Elma way, since we have some really cool suppliers here in DK. (1 really)

Steen🙂
 
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