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Aleph J illustrated build guide
Aleph J illustrated build guide
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Old 14th August 2016, 06:19 PM   #1841
Itsmee is offline Itsmee  England
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Aleph J illustrated build guide
Quote:
Originally Posted by qwertyl View Post
Any idea why and how to fix this?
It's around 1% differance, most likely the feedback resister tollerance, either use matched resistors or tweek one of the values.
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Old 14th August 2016, 06:20 PM   #1842
qwertyl is offline qwertyl  United Kingdom
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Quote:
Originally Posted by Zen Mod View Post
made by which schematic exactly ?
Schematic attached. I used boards for diyAudio Strore. Some photos here: Aleph J
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File Type: pdf aleph_j_sch.pdf (28.4 KB, 84 views)
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Old 14th August 2016, 06:27 PM   #1843
qwertyl is offline qwertyl  United Kingdom
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Quote:
Originally Posted by Itsmee View Post
It's around 1% differance, most likely the feedback resister tollerance, either use matched resistors or tweek one of the values.
You mean R4 (221k) on the schematic attached above, am I right?
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Old 14th August 2016, 06:38 PM   #1844
Zen Mod is offline Zen Mod  Serbia
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Aleph J illustrated build guide
1.78% difference

however , I can bet that my two ears are different for more than that

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Old 16th August 2016, 09:16 PM   #1845
qwertyl is offline qwertyl  United Kingdom
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Is Aleph gain set by R4/R1 (221k/22.1k)?
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Old 16th August 2016, 10:49 PM   #1846
TIC37 is offline TIC37  Sweden
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Default Transformer?

Since I concider to build this amplifier but have still to buy the PCB:s and transfomer amongst other then the question arise:

Original is 2x18V and about 300 VA, now we learn that it is possible to run the amp on 2x27V...

Since I still have to order a tranformer the question is if I should go for 2x18V as intended in the shematics or should I order 2x22V for example?
Seem that 2x22V or 2x24V should be doable without any other changes to the schematics and with a even better result.
To do or not to do, that is the question!
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Old 16th August 2016, 10:56 PM   #1847
wdecho is offline wdecho  United States
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The J runs pretty hot on 2 X 18V. All the Aleph series run much hotter than the other designs except the burning amp series.
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Old 16th August 2016, 11:24 PM   #1848
Zen Mod is offline Zen Mod  Serbia
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Aleph J illustrated build guide
TIC37 , some of musings about voltages etcetera , you can find here

when cascodes , why cascodes , when single outputs . when multiple

not exactly real tutorial , but plenty of crumbs in 140+ posts
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Old 17th August 2016, 12:18 AM   #1849
Itsmee is offline Itsmee  England
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Aleph J illustrated build guide
Quote:
Originally Posted by qwertyl View Post
Is Aleph gain set by R4/R1 (221k/22.1k)?
First of all, are you running the amplifier in balanced mode or single ended?
If balanced, R4 must equal R2 and R3 must equal R1.
If you are running single ended (-IN connected to 0V), the above is not so important.
The gain should be x10 (+20dB) and is determined by R4/R3, C1 will reduce the gain at low frequancys -3dB @ 7.2Hz.
It would be best to make gain measurements well away from the cutoff frequancy, somewhere around 1KHz.

Last edited by Itsmee; 17th August 2016 at 12:25 AM.
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Old 17th August 2016, 07:19 AM   #1850
qwertyl is offline qwertyl  United Kingdom
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Quote:
Originally Posted by Itsmee View Post
First of all, are you running the amplifier in balanced mode or single ended?
If balanced, R4 must equal R2 and R3 must equal R1.
If you are running single ended (-IN connected to 0V), the above is not so important.
The gain should be x10 (+20dB) and is determined by R4/R3, C1 will reduce the gain at low frequancys -3dB @ 7.2Hz.
It would be best to make gain measurements well away from the cutoff frequancy, somewhere around 1KHz.
Thanks for the explanation, it is very helpful. Actually I run Aleph in both modes - balanced in my digital setup and single ended when connected to Pearl 2.
I measured gain in single ended mode, -IN connected to GND, at 1kHz. I also measured and compared values of R1 - R4 in both channels and they are quite different, but within 1%. I will probably try to match them, or replace them with 0.1% resistors...
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