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Old 12th September 2010, 12:14 AM   #1821
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I found time to listen to the FF2010 linestage that Sam build. I recognised my product immediately because this stage sounds very dynamic and open. My own JG Self in on a loan so i can not compare directly to my air sculpture style construction. Sam uses a Salas Hypnotize in mono whereas i use a modified LC Audio Low Noise Supply in double mono so that gives a diffent result too.. If i remember correctly Sams implementation sounds a bit more full and musical. I was first concerned about the bandwidth limitaion he implemented at 1MHz with a Ricken Ohm resistor and a ferrrite coil but bridging the coil gave a sound that was slightly sharper and less energetic so he did a very good job here. The sound is very reveiling without getting nervous and 3 dimensional imaging is great. In fact this implementation of the LME49713 in shunt feedback is the closest i heard compared to my discrete open loop designs. Directly compared to my latest Open Loop Buffer the FF2010 has a very slight loss of micro detailing and a fractionally less full bodied character that borders on taste. The Open Loop Buffer is at an atvantage though because it has no voltage gain and no potmeter. I adjusted the gain with the 10Kohm pot in front of my poweramps. Sam did a wounderfull job here and to find a commercial stage that is that good for such a modest outlay is impossible i think.
In fact considering what i like i whould be hard pressed to name a commercial stage that i like better overall but it was of cause me that designed it to the parameters i think are important namely high speed, low distortion, good current drive and low noise so i am biased. I am confient though that this design measures up well because i have played it for numerous people without complaint.
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Old 12th September 2010, 02:42 PM   #1822
masag1 is offline masag1  Germany
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Default FF2010 Linestage

Hi Joachim!

Thank you very much for your the time you've spent with listening to our diy project. I know you are busy in R&D and building up your new company.

First of all I have to say, that it was my friend Klaus Scherm, he was the one who did the 3 D- pcb design, and the soldering of the first prototyp. And I don't forget the help of some of my Frickelfest colleagues. Thank you!

I only was fallen in love with your linestage design, starts the project running, and did some other little jobs.

We are going to modify the pcb again, we want to have space for a motorpoti, and maybe a mute relay.

Thanks for sharing your designs, Joachim. I have a lot of fun with them!

VG

Sam
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Old 14th September 2010, 04:05 PM   #1823
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Thanks, letīs see how the next PCB looks.
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Old 15th September 2010, 05:28 AM   #1824
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Hi Joachim,

I was searching for OPA211 comments (interviewing with TI on Thursday and was looking for info on their best opamps) and found your nice comments about my favorite National Opamp, the LME49713 CFB part (that I specified but am not actuallly good enough to design!)

Are you using the dip or metal can version? Metal cans are sonically better! Before we were all thrown out of National almost two years ago now we chose the 49713HA as our favorite sounding part for the most critical places of the audio signal path...when implemented properly!

Sorry everyone for not posting in many months but the job search has been keeping me busy. 22 months without a job and counting...

Best Audio Regards,

Audioman54
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Old 15th September 2010, 07:51 AM   #1825
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Quote:
Originally Posted by audioman54 View Post
Hi Joachim,

I was searching for OPA211 comments (interviewing with TI on Thursday and was looking for info on their best opamps) and found your nice comments about my favorite National Opamp, the LME49713 CFB part (that I specified but am not actuallly good enough to design!)

Are you using the dip or metal can version? Metal cans are sonically better! Before we were all thrown out of National almost two years ago now we chose the 49713HA as our favorite sounding part for the most critical places of the audio signal path...when implemented properly!

Sorry everyone for not posting in many months but the job search has been keeping me busy. 22 months without a job and counting...

Best Audio Regards,

Audioman54
/OT on

Mark, good luck with the interview! You deserve a good slot!

/OT off

jan didden
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Old 17th September 2010, 12:38 AM   #1826
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I tryed the LME49713 in plastic and also in metal can and the metal can sounds more dynamic and open but needs a bit time to settle in. Straight from the tube it sounded a bit harsh but that totally disappeared after some days on the juice. The linestage that Sam build uses the LME49713 inverted with a discrete buffer in front in a Baxandal type line stage.
I have to search for the diagram and then post it again here for your convenience.Unfortunately the metal can version is much more expensive here in Germany and a bit hard to get so for Diy i recommended the SMD version. Used inverted it is virtually distortion free, very fast and i like the 100mA driving ability that maks the sound in my opinion more effordless and it can drive a headphone quite well.
A lot is going on at my place here but my professional work got so much recently that i could not post much here. Jan Didden has send me a nearly stuffed Cordell Distortion Magnifier board so i am building that. Jan, many thanks, that comes really handy because i am building up my new lab to measure some things that i could not before. I am also building a noise scanner for BJT transistors because i had some trouble with flicker noise recently. It is a linear amp based on the Rosi and i will simply insert transistors and listen over headphone or speaker. Manuel Huber of FM acoustic told me many years ago that they do selecting for noise by ear so i am in good company. I will try also to isolate that noise and measure it. Unfortunately the Quantec noise analyser is not made any more and i also did not find one used or for lease so i try to do it that way. I also bought a Wandel & Goltermann precission generator and analyser so i am investing in my lab momentary. After having good success with phonostages and IC based Linestages i am now working on a discrete linestage.
By the way i like the LME49990 better then the OPA211. The OPA sounded a bit thin to my ears. I think there is a new chip based on the OPA211 from BB that is biased for Audio but i did not try that so far. What i did is try the OPA1642 Fet Op and this is one of my vavourite Fet Opamps together with the OP827. They all measue great but sound different. Why i can not tell but i suppose it has to do with PSU rejection, open loop output impedance, open loop bandwidth, gain - phase margin, noise, common mode rejection and so on. Ones the loop is closed over moden OPs there is not much to measure that whould diffentiate them aurally unfortunately so craetes the shism between subjectivist and objectivist. I belong in neather camp and when i can improve my music i do it even if i can not measure or explain the diffence right now. I WOULD of cause like to know what is going on, thus my investment into new equipment.
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Old 17th September 2010, 12:46 AM   #1827
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Here is the circuit of the LME49713 linestage. The servo is a OPA134.
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File Type: pdf LME49713 linestage.pdf (77.9 KB, 213 views)
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Old 17th September 2010, 07:38 AM   #1828
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Wow, i got now over 100.000 views and in the beginning i thought nobody was interested in my work !
The Noise Scanner is ready. I can test 2 NPN and 2 PNP transistors at ones. When i have found a good way to use it i will publish the circuit. I have a double row of contacts so i can use Japanese, American and European Pin Outs.
Maybe i just put it in front of one of my phonostages. Amplification will then be in the order of nearly 100dB because the Scanner has over 30dB of gain so i should be able to hear something.
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File Type: jpg Noise Scanner.jpg (92.2 KB, 408 views)
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Old 17th September 2010, 07:57 AM   #1829
Salas is offline Salas  Greece
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The art of noise. Spare WBT?
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Old 17th September 2010, 08:55 AM   #1830
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I had some samples lying around.
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