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Analog Line Level Preamplifiers , Passive Pre-amps, Crossovers, etc.

AD797 Preamp based on stolen trademark
AD797 Preamp based on stolen trademark
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Old 6th April 2020, 11:47 PM   #91
SyncTronX is offline SyncTronX  United States
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Quote:
Originally Posted by scott wurcer View Post
The Ohm meter forces current and measures voltage, you want this voltage to be <0.5V so you don't forward bias any internal diodes be they ESD devices or not. VTVM's had an Ohms/Volt for each scale, modern voltmeters don't. In reality just try it you should be OK, reverse the leads and see if it is the same.
Scott, Will do.
Question at least for me.
Should I plug these into a board and supply +-10VDC or +-15VDC to the
amps and measure the voltage readings across the pins? I assume I check
the real V+ and real V- values powering the device, and then follow your
guide to see if they are nulled at the correct pins.

5534: Nulled V+ @ P1-P8
797: Nulled V- @ P1-P5


w/o power:
LT1028: 130ohm P1-P8
5534: 12Kohm P1&P8. (this also being the rebranded LT1028).


Good stuff, thanks.


Cheers,
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Old 7th April 2020, 12:19 AM   #92
scott wurcer is offline scott wurcer  United States
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Quote:
Originally Posted by SyncTronX View Post
Scott, Will do.
Question at least for me.
Should I plug these into a board and supply +-10VDC or +-15VDC to the
amps and measure the voltage readings across the pins? I assume I check
Measuring the resistances from the null pins to the supplies should be enough.
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Old 4th May 2020, 02:30 AM   #93
gigigirl is offline gigigirl
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Default Did you finally get your clone

Berlusconi, Did you finally get your clone & if so what did it sound like,

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Old 4th May 2020, 03:55 AM   #94
Berlusconi is offline Berlusconi
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AD797 Preamp based on stolen trademark
Quote:
Originally Posted by gigigirl View Post
Berlusconi, Did you finally get your clone & if so what did it sound like,

Cheers
Hi gigigirl ,
The board hasn't arrived yet, but I will let you all know how the board worked before-and-after the replacement of the chip. I alredy have four AD797ANZ purchased from reputable supplier Conrad/Germany. It is interesting that here in Europe AD797ANZ isn't commonly on stock. Even at Farnell UK it is listed as: "Available until stock is exhausted"

This Corrona virus has delayed everything, not just Chinese shipping lines but also across Europe too. Even one delivery from Germany which usually arives within 4-7 days has delayed for three weeks.

And, Good morning. It is dawn here, almost 6 AM, so let's start the day early to get things done.
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Old 9th May 2020, 05:14 AM   #95
gigigirl is offline gigigirl
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Default Just spotted this unit

Hi I just spotted this unit on F/bay, May give it a try as I have a spare trans, suitable box & about 12 x AD797 spare in my collection of bits & pieces

AC15V-0-15V Audio Preamp Amplifier Board w/ Potentiometer Refer Germany MBL6010D | eBay

I really need the balanced version for my ultra low output phono, but this at least will give me an idea of what it sounds like.

Cheers & keep Safe
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Old 9th May 2020, 05:21 AM   #96
keilau is offline keilau  United States
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Location: Windy City, US
Quote:
Originally Posted by gigigirl View Post
Hi I just spotted this unit on F/bay, May give it a try as I have a spare trans, suitable box & about 12 x AD797 spare in my collection of bits & pieces

AC15V-0-15V Audio Preamp Amplifier Board w/ Potentiometer Refer Germany MBL6010D | eBay

I really need the balanced version for my ultra low output phono, but this at least will give me an idea of what it sounds like.

Cheers & keep Safe
Gigi, this is a line amp and not a phono stage. I am not even sure how it Refer Germany MBL6010D. It seems to be a NE5534 line amp board only.

The 4 on board trimmer look interesting. Do you know their function?

Last edited by keilau; 9th May 2020 at 05:25 AM.
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Old 9th May 2020, 10:25 PM   #97
Temaad is offline Temaad  Australia
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Will be interesting to hopefully hear their sound evaluations.
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Old 10th May 2020, 12:32 AM   #98
Lo_Tse is offline Lo_Tse  Canada
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Quote:
Originally Posted by gigigirl View Post
Hi I just spotted this unit on F/bay, May give it a try as I have a spare trans, suitable box & about 12 x AD797 spare in my collection of bits & pieces

AC15V-0-15V Audio Preamp Amplifier Board w/ Potentiometer Refer Germany MBL6010D | eBay

I really need the balanced version for my ultra low output phono, but this at least will give me an idea of what it sounds like.

Cheers & keep Safe
There are a number of these "MBL6010D" preamps available in EBAY, Aliexpress and TB. I bought a kit of this version a number of years ago.
?MBL6010D ?? ?????????? ?????-???
I like the PCB design (particularly the symmetrical layout) . Basically two stages of amplification per channel (basically 4 amplification modules for the whole amp). The seller actually provided the schematic of the amp. For this kit, the 4 trimmers are provided to adjust the voltage offset of each opamp in each module. I have 49710 in them and it is very quiet and it sounds very clean and neutral. I use a "clone DACT" type volume port and a R-core tranny.

Regards,.
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Old 10th May 2020, 02:15 AM   #99
gigigirl is offline gigigirl
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Default Yes I know it is a Pre

Hi keilau, Yes I know it is a pre amp. I need a balanced Pre for my phono amp and I thought buying the board I linked, would give me a good idea of what the unit sounds like. If it sounds OK I will buy one of the balanced versions.

Fully Balanced/Single-Ended Preamp Audio XLR/RCA Preamplifier MBL6010 Circuit 325646489324 | eBay

Cheers
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