njm4556 op amp - diyAudio
Go Back   Home > Forums > Amplifiers > Chip Amps

Chip Amps Amplifiers based on integrated circuits

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 8th November 2005, 05:54 PM   #1
diyAudio Member
 
crippledchicken's Avatar
 
Join Date: Dec 2003
Location: south east mo.
Default njm4556 op amp

i have the njm4556 for headphone output on my adcom GFP 565 preamp which the manual states 100 ohm impeadance but, the radio shack phones i just purchased have 60 ohm impeadance? are there better choices for op amp? or maybe add buffers such as LT1010, or buf634t which i have both of? if buffers would be best, anyone know of any Links where i could find out how to apply the buffers? thanks, crippledchicken
  Reply With Quote
Old 8th November 2005, 06:01 PM   #2
Did it Himself
diyAudio Member
 
richie00boy's Avatar
 
Join Date: Nov 2003
Location: Gloucestershire, England, UK
The BUF634 datasheet is very good and explains how to boost op-amps with it.

Any normal op-amp would be struggling to drive less than 600 ohms. I think OPA134 series will drive headphones OK directly. You'd have to check the datasheet for the NJM to confirm it's driving ability. You need to see what voltage the chip is running from then check the output current limit graphs.
__________________
www.readresearch.co.uk my website for UK diy audio people - designs, PCBs, kits and more.
  Reply With Quote
Old 8th November 2005, 06:06 PM   #3
diyAudio Member
 
crippledchicken's Avatar
 
Join Date: Dec 2003
Location: south east mo.
Quote:
Originally posted by richie00boy
The BUF634 datasheet is very good and explains how to boost op-amps with it.

Any normal op-amp would be struggling to drive less than 600 ohms. I think OPA134 series will drive headphones OK directly. You'd have to check the datasheet for the NJM to confirm it's driving ability. You need to see what voltage the chip is running from then check the output current limit graphs.
hi there, the njm4556 has lm78/79 15v. regulators driving it. could the opa 2134 also, maybe work since it's a dual as i have some of them? thanks
  Reply With Quote
Old 8th November 2005, 07:29 PM   #4
Did it Himself
diyAudio Member
 
richie00boy's Avatar
 
Join Date: Nov 2003
Location: Gloucestershire, England, UK
15V supply is pushing it. Yes the OPA134 series will work, whatever fits your board. However the NJM chip may be totally fine, just check the datasheet
__________________
www.readresearch.co.uk my website for UK diy audio people - designs, PCBs, kits and more.
  Reply With Quote
Old 8th November 2005, 08:12 PM   #5
diyAudio Member
 
crippledchicken's Avatar
 
Join Date: Dec 2003
Location: south east mo.
Quote:
Originally posted by richie00boy
15V supply is pushing it. Yes the OPA134 series will work, whatever fits your board. However the NJM chip may be totally fine, just check the datasheet
Thanks! Will Do
  Reply With Quote
Old 8th November 2005, 08:37 PM   #6
anatech is offline anatech  Canada
diyAudio Moderator
 
anatech's Avatar
 
Join Date: Jun 2004
Location: Georgetown, On
Hi crippledchicken,
You will find the 4556 is used in almost every product without an amplifier to drive headphones. It was designed for this.

If you want better performance, I would suggest building an outboard unit. There is only so much you can do with a single op amp to get rid of heat. Then you can build better power supplies and use the better op amps to full effect.

-Chris
  Reply With Quote
Old 9th November 2005, 01:24 AM   #7
diyAudio Member
 
crippledchicken's Avatar
 
Join Date: Dec 2003
Location: south east mo.
Quote:
Originally posted by anatech
Hi crippledchicken,
You will find the 4556 is used in almost every product without an amplifier to drive headphones. It was designed for this.

If you want better performance, I would suggest building an outboard unit. There is only so much you can do with a single op amp to get rid of heat. Then you can build better power supplies and use the better op amps to full effect.

-Chris
hi anatech i think youre right, i have seen this chip several times used to drive headphones. i think i'll be checking into building an external amp. Thanks, crippledchicken


  Reply With Quote
Old 9th November 2005, 10:34 AM   #8
diyAudio Member
 
Join Date: Jul 2004
Location: Berlin
There are certainly better performing op-amps out there... (ok, I didn't look at the NJM4556 datasheet yet )
Do you need a DIP-8 or SO-8 package?
  Reply With Quote
Old 9th November 2005, 03:01 PM   #9
diyAudio Member
 
crippledchicken's Avatar
 
Join Date: Dec 2003
Location: south east mo.
Quote:
Originally posted by Dominique
There are certainly better performing op-amps out there... (ok, I didn't look at the NJM4556 datasheet yet )
Do you need a DIP-8 or SO-8 package?
hi Dominique, what i need are the DIP-8. i have, opa2132, opa2134, opa2604, lm6172,, AD826, LT1364, as well as the LT1010, and BUF634T buffers on hand if any of these could be implemented for better performance? thanks for any ideas, crippledchicken

  Reply With Quote
Old 11th November 2005, 01:56 AM   #10
diyAudio Member
 
Join Date: Jul 2004
Location: Berlin
I had in mind to simply replace the op-amp for a stronger one, but after checking my gathered data, I couldn't find op-amps in a DIP package better than the NJM4556 (low impedance output), but only in SOIC and TO packages. Most of them are high speed, so it's not clear if they would work fine without tweaks in your existing circuit anyway.

Either you simply try your new headphones and listen if there's more distortion, build an outboard unit like anatech proposed, add a little pcb with a buffer in your preamp (then you could replace the NJM4556 for a weaker, but better op-amp), or use a SOIC op-amp with a SOIC to DIP adapter (but it's not guaranteed to work fine in your existing preamp (because all those strong SOICS on my list were high speed )

Sorry I couldn't be of much help!
Cheers,
Dominique
  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



New To Site? Need Help?

All times are GMT. The time now is 09:54 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