Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Analogue Source Turntables, Tonearms, Cartridges, Phono Stages, Tuners, Tape Recorders, etc.

Simplistic NJFET RIAA
Simplistic NJFET RIAA
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 29th July 2009, 02:03 PM   #2091
Salas is online now Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Simplistic NJFET RIAA
Default Re: Sound fading away with higher voltage

Quote:
Originally posted by iwahn
Hello, I have built the RIAA and it worked well with three small 9 volt batteries in series. With the Shunt, and higher voltage (29 v), I find that the volume is much reduced. The sound is also distorted. The RIAA-stage is built with 2sk170 gr, idss 5.9-6.5 mA. The bl grade is difficult to get. What changes can be done?
The Idss you built it with has directly to do with the voltage and loading values used. The idss range I mention on the schematics, is central to the design, and to be followed. Link me to the exact version you built and I will simulate it with 6.2mA Idss average so to let you know where is best to set the shunt and/or possibly change some resistor value. What is the output of your cartridge?
  Reply With Quote
Old 29th July 2009, 08:56 PM   #2092
iwahn is offline iwahn
diyAudio Member
 
Join Date: Jun 2002
Location: norway
Hi Salas. I downloaded PSGR´s RIAA Document Beta2, and built the version with 48 db amplifying. The pick up is a Denon dl103, 0.3 mv.
  Reply With Quote
Old 30th July 2009, 12:45 AM   #2093
Salas is online now Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Simplistic NJFET RIAA
Well, your choices are at odds with two things. One is having 2SK170GR and plugging them in a 8-9mA Idss BL recommended schematic, second is that your cart is too low for choosing 48dB gain.

Anyway, here are the values for your GRs, 29V shunt, and Denon DL103. Even the load resistor is OK as it is recommended. For the 46k, use two 92k in parallel. Take out one Led and jumper its position. You use 3. Make sure that your Leds are 1.8V each, and that your GRs are matched per position between channels. Use your strongest pair for first stage.

Regards.
Attached Images
File Type: gif gr&103.gif (7.4 KB, 458 views)
  Reply With Quote
Old 30th July 2009, 01:30 AM   #2094
iwahn is offline iwahn
diyAudio Member
 
Join Date: Jun 2002
Location: norway
Thank you very much! I will try this immediately. The reason why I chose 48 db gain, is that I plan to buy a new cart. Probably a Denon dl 160.

best regards
  Reply With Quote
Old 30th July 2009, 01:42 AM   #2095
Salas is online now Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Simplistic NJFET RIAA
Yes, but to hear well at all with your DL103 you will need some gain meantime. Before you decide on a new one, remove 103's plastic body. Nude is a whole new cart. There are guides. Even a video on YouTube.

Tell me if we succeeded with the new values, so to know there is not something else going wrong when you finish. Then you tell us more about system and sound. Possibly showing a photo too.

If finally you will need less dB, I am here to let you know how.
Attached Images
File Type: gif nudevid103.gif (63.4 KB, 421 views)
  Reply With Quote
Old 30th July 2009, 01:49 AM   #2096
Tham is offline Tham  Malaysia
diyAudio Member
 
Join Date: Jun 2006
Salas, thanks for looking. I left some room for larger components for RIAA and the output cap but do not think that it will be sufficient for a FT-2 and so on. May do another one again later p2p on Teflon sheet when I get hold of the recommended components .
  Reply With Quote
Old 30th July 2009, 01:53 AM   #2097
Salas is online now Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Simplistic NJFET RIAA
That will be best. One nice and cheap with successful tone as you already have, and a bigger board experimental with parts one, so to compare step by step and tune in for that elusive synergistic uber tone! Did you add any gain to your T-Amp, or you feel its OK for your room after all? Killed the lights noise?
  Reply With Quote
Old 30th July 2009, 02:17 AM   #2098
Tham is offline Tham  Malaysia
diyAudio Member
 
Join Date: Jun 2006
Salas, it is actually loud enough with volume control almost all the way up. Do not think I need to increase the gain of the T amp unless the system is moved to a bigger room.

It is amazing the noise was kept so low at those listening level. Those valve phono stages that I have before (ARC SP8, Jadis JP80) are so much noisier in comparison.

Will try the cap bypass at phono primary side when I get the parts soon.
  Reply With Quote
Old 30th July 2009, 02:30 AM   #2099
Salas is online now Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Simplistic NJFET RIAA
Maybe its better to have more 0.1uF X2 caps so to kill right on the switches of the fluorescent lights if it is difficult to get rid of it.

As it is with cheap almost random parts, is it comparable for tone quality with those expensive and revered phono stages, besides the noise level being better? What is the TT and arm again?
  Reply With Quote
Old 30th July 2009, 02:43 AM   #2100
Tham is offline Tham  Malaysia
diyAudio Member
 
Join Date: Jun 2006
It is a heavy plinthed Lenco L75 tt with an Audio Technica AT16P 10" arm.

With random parts tonally it is a little thin in the midrange that I hope to improve on using good components. Bass is tight and tuneful and quite extended while high is crystal clear because of the very low noise level and never harsh even with the new supertweeter not optimally integrated.
  Reply With Quote

Reply


Simplistic NJFET RIAAHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


New To Site? Need Help?

All times are GMT. The time now is 04:35 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki