Simple MM only RIAA preamp

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#42
OK, but suppose you HAVE a very powerful voltage source like a Jung, Sulzer regulator or even a big fat cap, why trying to draw constant current?

At work have a similar thing but in that case it's about discharging smooting caps because the current consumption is very unequal when a relay is on or off.
 
#43
x-pro said:
Hi all,

here is the link to the article (unfortunately, in Russian) I've published in 1999 in "RadioHobby" in Kiev about the original idea behing Creek Audio OBH-8 preamplifier. Since that time newer versions of this circuit are used in the current line of OBH preamps. However, this circuit is a good example of what could be done with few transistors. The sound of this circuit is good and it is very DIY friendly 🙂 .

http://vlab.netsys.ru/audio/lpcor7.stm

It is single-ended class A with passive EQ. What else would you wish? 🙂

Technical Data of this preamp:

Gain - 90

SNR - better than 70 dB A-wtd ref 5 mV 1kHz input

RIAA deviation +/- 0.5 dB 50Hz-30kHz, -3 dB at 20 Hz

Max. output 5V RMS

Distortion for 1V output - less than 0.01% at 1 kHz

To prevent possible questions - it is my own design and the original publication was made with permission from Creek. The circuit is copyright of Creek Audio Limited (it is printed in the original article, unfortunately on the linked web site they cut the picture and lost it... .

Enjoy

Al
Click to expand...

Anyone who knows where the schematic went to? The page above is removed, or moved.
 
#44
This one?
 

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#48
Component values in X-pro's preamp?

X-pro, thanks for the interesting schematic. The Creek phono preamp has consistently received quite favourable reviews in the magazines I have read.

Unfortunately the picture resolution makes is difficult to read some of the resistor values. I'd rather get them directly from the source than guess them myself...

Could you perhaps post the values of:
R2, R3, R7, R9, R11, R14 and R16.

The transistors are BC550B, I suppose?

Best regards,
Pekka U.
 
#49
Re: Component values in X-pro's preamp?

pekka said:
X-pro, thanks for the interesting schematic. The Creek phono preamp has consistently received quite favourable reviews in the magazines I have read.

Unfortunately the picture resolution makes is difficult to read some of the resistor values. I'd rather get them directly from the source than guess them myself...

Could you perhaps post the values of:
R2, R3, R7, R9, R11, R14 and R16.

The transistors are BC550B, I suppose?

Best regards,
Pekka U.
Click to expand...

No problem:

R2 = 150K
R3 = K62
R7 = 68K
R9 = K33
R11 = 100K
R14 = 22K
R16 = K22

Transistors are BC550B or C . It may be nesessary to adjust the value of R5 (1M2) in the range from 1M0 to 2.2M depending on the actual make of transistors, otherwise there could be some deviation from correct RIAA curve below 50 Hz.

x-pro
 
#57
Re: schematic

maxpou said:
Hi X-Pro,
if is possible i would like to have the schematic of your riaa and i would like you to look at this thread and what do you think about it. Thank You! Maxpou

http://www.diyaudio.com/forums/showthread.php?s=&threadid=114886
Click to expand...

I'll have a look, thanks.

arnoldc said:
Hi x-pro, did you design the OBH-15 too? Are they discrete like the 8 or opamp based?
Click to expand...

No, OBH-15 was made after I've left and I have no information about what is inside, sorry.

Cheers

Alex
 
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