Aleph H Schematic - Revealed at Last - Page 2 - diyAudio
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Old 15th November 2013, 12:28 PM   #11
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I think that is to set it at unity gain?
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Old 15th November 2013, 01:14 PM   #12
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gain is R7/R5 in SE

in fact , R5 is redundant - R3 is there ...... as is for balanced , grounded for SE
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Old 23rd November 2013, 10:54 AM   #13
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I have a question... I have a couple of the mini aleph boards and I was planning on making those into a mini aleph's but sine this came up, I was thinking mini H instead. I do need a nice headphone amplifier anyway.

Problem I am having is when I look at the schematic, at the pictures I the 6moons review, and then at the boards -- where in the schematic are Q7 and Q8 (mostly because the schematic goes from Q6 to Q9)?

In the pictures in the review, Q7 looks populated by something, but I am not sure what it might be exactly. Just a lot confused by this and anyone know what this might be? Or am I missing something?
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Old 23rd November 2013, 11:52 AM   #14
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I am 99% sure this PCB and schematic match. Are these the boards you are using?

Click the image to open in full size.

Click the image to open in full size.


Click the image to open in full size.
In this photo you can assume the output transistors (Q6, Q7) are tucked under the PCB to make room for layout issues.
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Old 23rd November 2013, 04:07 PM   #15
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Yep, those are the same BrianGT boards I've got with a "0711" written on the snap off power boards.

I am just not really getting it fully, because even when I compare metalman's schemattic to the one you posted, yours has the Q7 and Q8 in the diagram. I am not all that engineering minded, but I can follow a schematic with a relative moderate degree of difficulty. But what am I missing when I look at the two?

Yours is two channel? But then if I follow Q3, yours will lead to R4 and R5 then ground, while matalman's leads to R12 and R13 then ground.

I am sorry to ask all this, but I am sitting here just really, really confused.
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Old 23rd November 2013, 04:38 PM   #16
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You keep saying "Q8"... That's on a snap-off board. Is that the right number?

Q3 is the active component of the Constant Current Source that feeds power to the input preamp diff. pair, Q1/Q2.

Quote:
Originally Posted by metalman
1) The component numbers in my schematic DO NOT MATCH with the component numbers for the Aleph-Mini group buy boards. Be careful to ensure the right components end up in the right circuit locations.
Good advice. The PCB you have matches the schematic I posted - so now all you need to do is substitute the Aleph H values into the proper places on your PCB. Easy.

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Old 23rd November 2013, 05:12 PM   #17
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Oh geez... I read that originally way back when metalman posted it, but totally forgot about it since then.

Thanks for pointing that out to me again.

I'll take another look with pen and pencil in hand and try to go from there. Thanks again 6L6.
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Old 3rd December 2013, 01:58 PM   #18
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Default Lots of questions before starting the build.

Hi!

Today am using a modified “lovely cube”, a really good Lehmann Black Cube Linear Clone. It´s really fantastic, but lacks a little bit of soul. I noticed that if I reduced the feedback of the opamp the amp comes to life. My idea is to get rid if the opamps and heavy feedback entirety and get a little more back to basics.

Therefore I’m looking for a good simple single ended design without a huge amount of feedback to drive my 300Ohms sennheisers and this looks like it fits the bill. Has someone tried it out? It it as good as the &moons review suggest? Is there any similar simple design that performs considerably better?

Before I start out I have some questions:

-Am I correct in my assumption that only Q1 and Q2 need to be matched?

-Is there any good substitute for the ZTX450 in this application? Bc550?

-I would really need higher input impedance for my application. Can I make R4 a higher value, lets say 100K as in other aleph mini designs as in post #14? Is the single ended gain set by R8 and R4?

- In the pictures from the 6moons review the transformer seems to be 15v and I will give 21v rectified. The schematics says 15v. Will it be ok to run it at 15-16v rectified?

-Is there any suitable PCB designs available so I can make my own PCB?

Thanks for sharing the design!

Best Regards Christian
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Old 3rd December 2013, 02:36 PM   #19
6L6 is offline 6L6  United States
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Christian,

Go to this website - Order | Chipamp.com

Scroll to the bottom and look for "ALEPH-TH-PCB" and "ALEPH-PS-PCB" -- those are the circuit boards in this project.

BC550 is a good substitue - but check the pinout, it is different from the ZTX
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Old 3rd December 2013, 03:08 PM   #20
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Thanks for the quick reply!

When you live in Swewden you pay more in tax and PP than for the parts.... I was looking for a layout so I can etch myself. On the other hand it could be fun to learn diptrace and do it my self.
B.R Christian
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