LME49990 design note - Page 2 - diyAudio
Go Back   Home > Forums > Source & Line > Analog Line Level

Analog Line Level Preamplifiers , Passive Pre-amps, Crossovers, etc.

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 9th October 2012, 04:54 PM   #11
JensH is offline JensH  Denmark
diyAudio Member
 
Join Date: Jul 2009
Which it worth trying.

When you write "This was as noisy as heck, transmitting all the noise from the tonearm ground", what kind of noise are you talking about here? White noise, hum, RFI (from radio stations etc.) or?

What is the impedance of the pick up? If it is not very low you may get more noise with the LME49990 than with the OPA627.
  Reply With Quote
Old 9th October 2012, 04:59 PM   #12
ahaja is offline ahaja  Poland
diyAudio Member
 
Join Date: Oct 2004
Location: Poznań
I use with lme49990 a combo 100n(NPO smd)/100uF(Silmic). I got no problems with it.

This phono stage (47Labs project) has active riaa correction in the feedback, and HF (2122Hz) are cut in 1 stage. So it should not be a problem. With high gain circuits like this one enclosure is important.
If you have RFI problems cut them on the input.

I got a combo of 47Labs/Phonoclone and I place a RC (2k2/470pF) on the input of first stage. From IN- to ground.

Small ferrit placed on signal wire also can help.

Tantal caps can not cause burning fuse.
__________________
Dual mono preamp Turntable
HUSARIAA
  Reply With Quote
Old 9th October 2012, 04:59 PM   #13
BigE is offline BigE  Canada
diyAudio Member
 
Join Date: Aug 2008
Location: Toronto
When you moved the tonearm from side to side, you could hear the bearing noise from the arm. A light grinding sort of sound that stopped when you stopped moving it.
  Reply With Quote
Old 9th October 2012, 05:05 PM   #14
BigE is offline BigE  Canada
diyAudio Member
 
Join Date: Aug 2008
Location: Toronto
ahaja, do you put the 100nF at the power supply or at the legs of the chips? did you use the LME49990 in the first stage?

Your RC is 2K2 || 470 pF?
  Reply With Quote
Old 9th October 2012, 06:33 PM   #15
ahaja is offline ahaja  Poland
diyAudio Member
 
Join Date: Oct 2004
Location: Poznań
I do it:
as close as possible to opamp power pins. From V- to GND and from V+ to GND.
Look: https://picasaweb.google.com/1154538...91848717975554

RC:
not parallel, in series.
Connection:
IN- resistor capacitor ground
__________________
Dual mono preamp Turntable
HUSARIAA
  Reply With Quote
Old 9th October 2012, 06:42 PM   #16
BigE is offline BigE  Canada
diyAudio Member
 
Join Date: Aug 2008
Location: Toronto
The RC series should also be as close as possible to the IN- pin, or does that matter?

I will try this with the OPA627 first, then add the correct bypass cap arrangment to the LME adapter circuit before trying that again.

thanks!
  Reply With Quote
Old 9th October 2012, 07:18 PM   #17
diyAudio Member
 
sachu888's Avatar
 
Join Date: Jul 2010
Location: India
I am using 49990 in my DIY CNC Phonostage with excellent results.There is absolutely no hum,hiss.Its very quiet and musical.I have tried different Opamps like Opa2134,2107,Lm4562,Ad823 etc,but 49990 sounds best in my system.I am running it with my DIY power supply at +/-11V
Click the image to open in full size.

Regards,
Sachin
  Reply With Quote
Old 9th October 2012, 10:01 PM   #18
diyAudio Member
 
Join Date: Jun 2011
I would have simply agreed with 5th element, but I note Doug Self's take on power supply bypassing, where he suggests that it's preferable to connect small PSU bypass caps from rail to rail in the case of those applied to opamps and other chips, but to be careful with caps from rail to ground, tending to limit the larger ones to the points where the supply comes onto the board, lest noise is coupled into the ground system resulting in degraded SNR.
  Reply With Quote
Old 9th October 2012, 10:19 PM   #19
ahaja is offline ahaja  Poland
diyAudio Member
 
Join Date: Oct 2004
Location: Poznań
schem
__________________
Dual mono preamp Turntable
HUSARIAA
  Reply With Quote
Old 9th October 2012, 10:30 PM   #20
diyAudio Member
 
s3tup's Avatar
 
Join Date: Dec 2004
Location: Israel
^^Doug Self is right. The easiest and fastest way to bypass these adaptors is to place some 0.1uf+ mkt/mkp right across the rails, on the IC itself, with shortest leads. This is usually doable, as we are talking about a single cap, with bent-to-suit pins...
__________________
The missing link between lead and gold in alchemist's world was BS and commerce.
  Reply With Quote

Reply


Hide 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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
LME49990 Audio Op-Amp - better than AD797? tiefbassuebertr Solid State 37 12th October 2013 08:15 PM
LM4702 reference design note 1490 - ideal 1st amplifier? Spasticteapot Solid State 8 20th February 2013 10:47 PM
On a design note jjl Full Range 5 30th January 2012 08:22 PM
FS: Dual LME49990 on DIP adapter theAnonymous1 Swap Meet 0 7th September 2011 07:28 PM
FS: Audio Note TRANS-010; Audio Note 20H 50mA choke; Black Gate Wk "power tank" Joseph0 Swap Meet 1 24th May 2006 06:17 AM


New To Site? Need Help?

All times are GMT. The time now is 05:29 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2