Mpp - Page 766

Joachim Gerhard · 7th November 2012, 09:47 PM

This is really interesting :IMD - Something New

FdW · 7th November 2012, 09:51 PM

Quote:

Originally Posted by Joachim Gerhard

I do not know why but i get a lot of samples from a lot of companies. Maybe they think i have good ears ?

Or

they hope you do not

Joachim Gerhard · 7th November 2012, 09:57 PM

Sure, i do not care. But testing a lot i do and i give back reports. I am consistently bad C:

Mooly · 8th November 2012, 06:24 PM

Many posts have been deleted at FdW's request (as they contain what could be misleading info) although this action should be seen as a one off.

RCruz · 8th November 2012, 06:27 PM

Thank you so much for the prompt action Mooly

Mooly · 8th November 2012, 06:30 PM

Your welcome

FdW · 8th November 2012, 07:02 PM

Quote:

Originally Posted by Mooly

Many posts have been deleted at FdW's request (as they contain what could be misleading info) although this action should be seen as a one off.

Thanks Mooly

Joachim Gerhard · 03:06 AM

Today i got one channel of my transimpedance tube RIAA for ETF 2012 working.
This did not come easy. Design and build took me the better part of one year, on and off.
I have great help from a very experience friend but i ran into several problems that drove me crazy. First i had a problem with the current sources and then i got oscillation. That proved to be a grounding issue of the heater supply and chassis.
Anyway, it works. With near textbook values i get a response that is flat from 100Hz to 100kHz ( -3dB ), under 100Hz i have some loss in the bass. That can be tuned in, tomorrow. I use a self conducting cascode with cascoded depletion mosfets at the input and a mü follower at the output so i have tremendous gain, around x266 in the input and
33 in the output for a total of 8800. That amplifies 0,5mV P-P to 4,4V P-P. I use very high transconductance russian tubes at the input and an E188CC at the output. Output impedance is 140 Ohm and there is a volume control in the RIAA. Noise will be low enough for medium to high output MC. For low output MC i build a box with transformers. At the moment i have no desire to share the circuit diagram. I have simply too much to do plus the crazy Paradise project. I hope i can get it working before ETF on both channels.

The Space Egg Corp · 9th November 2012, 03:59 AM

Lookin' good Joachim !

You must get to bed earlier though.
( that's what I'm told anyhow )

Best time to work; the wee hours...
...just switched off the iron.

Good luck with channel 'B'.

Cheers

Si.

Joachim Gerhard · 9th November 2012, 09:05 PM

I got the tube RIAA tuned. It spans 4 octaves from 20Hz to 200kHz ( -3dB ). I kept a small rolloff in the bass. I do not think it is a good idea to extent the deep bass response too much in a tube RIAA. High frequency extension is somewhat dependent on the volume control in the RIAA. Under worse case conditions ( potmeter in the middle position ) i still get 70kHz ( -3dB ). I put the amplification down by 6dB so it has now a maximum gain of x 4400. 1mV input give 4,4V output. The 1kHz square looks good with anti RIAA.
Photo later.

8th November 2012, 06:24 PM	#7654
Mooly diyAudio Moderator Join Date: Sep 2007	Many posts have been deleted at FdW's request (as they contain what could be misleading info) although this action should be seen as a one off. __________________ ------------------------------------------------------- *A simulation free zone.* *Design it, build it, test it.*

8th November 2012, 06:27 PM	#7655
RCruz diyAudio Member Join Date: Sep 2006 Location: Saxon Blog Entries: 1	Thank you so much for the prompt action Mooly __________________ RC

8th November 2012, 06:30 PM	#7656
Mooly diyAudio Moderator Join Date: Sep 2007	Your welcome __________________ ------------------------------------------------------- *A simulation free zone.* *Design it, build it, test it.*

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7th November 2012, 09:47 PM	#7651
Joachim Gerhard diyAudio Member Join Date: Mar 2009	This is really interesting :IMD - Something New

7th November 2012, 09:57 PM	#7653
Joachim Gerhard diyAudio Member Join Date: Mar 2009	Sure, i do not care. But testing a lot i do and i give back reports. I am consistently bad C:

9th November 2012, 03:59 AM	#7659
The Space Egg Corp diyAudio Member Join Date: Sep 2010 Location: London & Miami Blog Entries: 13	Lookin' good Joachim ! You must get to bed earlier though. ( that's what I'm told anyhow ) Best time to work; the wee hours... ...just switched off the iron. Good luck with channel 'B'. Cheers Si.

9th November 2012, 09:05 PM	#7660
Joachim Gerhard diyAudio Member Join Date: Mar 2009	I got the tube RIAA tuned. It spans 4 octaves from 20Hz to 200kHz ( -3dB ). I kept a small rolloff in the bass. I do not think it is a good idea to extent the deep bass response too much in a tube RIAA. High frequency extension is somewhat dependent on the volume control in the RIAA. Under worse case conditions ( potmeter in the middle position ) i still get 70kHz ( -3dB ). I put the amplification down by 6dB so it has now a maximum gain of x 4400. 1mV input give 4,4V output. The 1kHz square looks good with anti RIAA. Photo later.