Simplistic NJFET RIAA - Page 360

Salas · 19th April 2010, 09:14 PM

Yes.

merlin el mago · 19th April 2010, 09:33 PM

Tomorrow I will do the measurements & I will let you know, thanks again for your kind patience with me.

vgeorge · 20th April 2010, 07:51 AM

As I am almost finished collecting parts for my second Riaa buit, got a little confused regarding R3 value. I am going to built the 56db version for my Sheleter 901 and R3 is stated as 43K, however doing my calculations here, http://www.kabusa.com/riaa.htm I think I should have a 47k R3 for the following values:
R3 = 43,06 and 42,95 takman carbon
R4 = 6,829k and 6,835k shinkoh
c2 = 47,05n and 47,01n Obligato // silver mica
c3 = 16,009 and 16,013 Russian silver mica // silver mica
(C2 and C3 can be adjusted to lower values)

Also thinking to try for C4 a Hovland instead of the usual FT-3(I have both, what do you think?

RCruz · 20th April 2010, 09:59 AM

Hi vgeorge

You can not input Salas riaa values directly into kabusa.

Salas calculates the values by simulating the whole circuit.

Let me know R1 and R5 real values and I will see if you need any adjustments

What type of cap is the hovland ?

vgeorge · 20th April 2010, 10:09 AM

Hovland is this one: Hovland Company: Products: MusiCap Capacitors
They have good reviews usually.

R1 = 6,175k and 6,180k shinkoh
R5 = 1,009M and 1,010M Takman carbon

Thanks.

merlin el mago · 02:40 PM

Some general rules IMHO about caps:

Best dielectic: 1st air, 2nd teflon & after the rest of materials.

Best kind: 1st foil, 2nd metallized.

Best conductors: 1st silver, 2nd copper.

Better take always the cap higher VDC rated, thicker dielectric & thicker conductors so less resistance & better spread.

I owned some Hovlands, are very good caps polypropylene film & aluminum foil, so very similar to Obbigatos that are also polypropylene film & aluminum foil, if same kind of materials choose if possible the higher VDC rated.

For C2 better use silver mica as suggested Salas

merlin el mago · 20th April 2010, 02:46 PM

I am really surprised, with DVM in ACmV mode Side One trck, 3,4 & 5 & Side Two track 5 always the DVM is changing the reading & not fixed AC voltage is measured

Salas · 20th April 2010, 04:07 PM

Can't keep relatively steady on 300Hz second side even? Try 2V AC scale.

merlin el mago · 20th April 2010, 06:47 PM

DVM minimum AC scale is 200~V

Salas · 20th April 2010, 06:50 PM

Your DVM should be capable of measuring AC over some decent bandwidth and have some scale steps. Anyway does it show something at 200VAC scale when connected on outputs as you play the special tracks?

20th April 2010, 02:37 PM	#3596
merlin el mago diyAudio Member Join Date: Sep 2009 Location: Catalonia new Europe state	Some general rules IMHO about caps: Best dielectic: 1st air, 2nd teflon & after the rest of materials. Best kind: 1st foil, 2nd metallized. Best conductors: 1st silver, 2nd copper. Better take always the cap higher VDC rated, thicker dielectric & thicker conductors so less resistance & better spread. I owned some Hovlands, are very good caps polypropylene film & aluminum foil, so very similar to Obbigatos that are also polypropylene film & aluminum foil, if same kind of materials choose if possible the higher VDC rated. For C2 better use silver mica as suggested Salas Last edited by merlin el mago; 20th April 2010 at 02:40 PM.

20th April 2010, 02:46 PM	#3597
merlin el mago diyAudio Member Join Date: Sep 2009 Location: Catalonia new Europe state	Test record measurements I am really surprised, with DVM in ACmV mode Side One trck, 3,4 & 5 & Side Two track 5 always the DVM is changing the reading & not fixed AC voltage is measured

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19th April 2010, 09:14 PM	#3591
Salas diyAudio Chief Moderator Join Date: Oct 2002 Location: Athens-Greece	Yes.

19th April 2010, 09:33 PM	#3592
merlin el mago diyAudio Member Join Date: Sep 2009 Location: Catalonia new Europe state	Tomorrow I will do the measurements & I will let you know, thanks again for your kind patience with me.

20th April 2010, 07:51 AM	#3593
vgeorge diyAudio Member Join Date: Mar 2004 Location: poros island	As I am almost finished collecting parts for my second Riaa buit, got a little confused regarding R3 value. I am going to built the 56db version for my Sheleter 901 and R3 is stated as 43K, however doing my calculations here, http://www.kabusa.com/riaa.htm I think I should have a 47k R3 for the following values: R3 = 43,06 and 42,95 takman carbon R4 = 6,829k and 6,835k shinkoh c2 = 47,05n and 47,01n Obligato // silver mica c3 = 16,009 and 16,013 Russian silver mica // silver mica (C2 and C3 can be adjusted to lower values) Also thinking to try for C4 a Hovland instead of the usual FT-3(I have both, what do you think?

20th April 2010, 09:59 AM	#3594
RCruz diyAudio Member Join Date: Sep 2006 Location: Saxon Blog Entries: 1	Hi vgeorge You can not input Salas riaa values directly into kabusa. Salas calculates the values by simulating the whole circuit. Let me know R1 and R5 real values and I will see if you need any adjustments What type of cap is the hovland ?

20th April 2010, 10:09 AM	#3595
vgeorge diyAudio Member Join Date: Mar 2004 Location: poros island	Hovland is this one: Hovland Company: Products: MusiCap Capacitors They have good reviews usually. R1 = 6,175k and 6,180k shinkoh R5 = 1,009M and 1,010M Takman carbon Thanks.

20th April 2010, 04:07 PM	#3598
Salas diyAudio Chief Moderator Join Date: Oct 2002 Location: Athens-Greece	Can't keep relatively steady on 300Hz second side even? Try 2V AC scale.

20th April 2010, 06:47 PM	#3599
merlin el mago diyAudio Member Join Date: Sep 2009 Location: Catalonia new Europe state	DVM minimum AC scale is 200~V

20th April 2010, 06:50 PM	#3600
Salas diyAudio Chief Moderator Join Date: Oct 2002 Location: Athens-Greece	Your DVM should be capable of measuring AC over some decent bandwidth and have some scale steps. Anyway does it show something at 200VAC scale when connected on outputs as you play the special tracks?