Just for perspective, the typical input bias current for the LM4562 is 5X less than the LT1115, and 20X less than the NE5532. In addition to reducing noise using MM cartridges (0.5-1H typical inductances!), there is more freedom choosing feedback components without having to worry so much about extra offset voltage.
SY said:
If you look at the open loop gain vs frequency, it is ugly. Open loop bandwidth is 10Hz or so! Yes, that Herz, NOT kiloHerz!
So, the feedback in a closed loop config starts to loose effectiveness from 10Hz upwards, and that causes the rises of the hf THD once the harmonics come out of the noise.
The low THD of this thing is NOT due to its high ol bandwidth, but in some way they have made this thing extremely linear open loop.
Jan Didden
Has anybody found a distributor for this part yet? I checked Digi-Key, Newark, Allied, Mouser, and Arrow. Either there is no hit for the LM4562, or in the case of Arrow, a hit but no stock. I tried Future, but their search just hangs up for 10-15 min without spitting out any results - a bad omen in any case.
The LT1115 has similar open loop bandwidth characteristics to the LM4562 and similar behavior of IM and THD vs amplitude. Linear shows current source loading in their application circuit for an RIAA preamp. Makes me wonder... BTW, given the extremely high open loop gain of both parts, I wouldn't expect an open loop BW of much higher than 10Hz in any case.
SY said:
Stuart, yes, I understood your post that you suggested that the rise of THD with freq was due to noise, which isn't the case.
Agree with the quoted post. The rise of THD above 10k is because at that freq (due to decreasing feedback effectiveness) the THD starts to rise above the noise. I would guess that if we could see below the noise the THD would steadily decrease with freq to 10Hz and flatten out from there downwards...
Jan Didden
TI is not to be outdone:
http://www.ti.com/corp/docs/landing/opa365/index.htm?DCMP=hpa_amp_opa365&HQS=NotApplicable+PA+opa365
Jan Didden
http://www.ti.com/corp/docs/landing/opa365/index.htm?DCMP=hpa_amp_opa365&HQS=NotApplicable+PA+opa365
Jan Didden
Re: So, how does it sound?
It sounds great! I am currently using samples of this part as the front end (instrumentation amp) of my 'Twisted Sibling' preamp, as well as the input buffer into a kookaburra (with clean separate supplies for digital and analog side).
It sounds excellent, nothing evil to report in the least. I am seriously considering of making this my new standard part for jobs like this when I can get them in qty > 5
.
Cheers!
Russ
clem_o said:
It sounds great! I am currently using samples of this part as the front end (instrumentation amp) of my 'Twisted Sibling' preamp, as well as the input buffer into a kookaburra (with clean separate supplies for digital and analog side).
It sounds excellent, nothing evil to report in the least. I am seriously considering of making this my new standard part for jobs like this when I can get them in qty > 5
.Cheers!
Russ
LM4562 press release
National Semiconductor published a press release today, http://www.national.com/news/item/0,1735,1195,00.html
National Semiconductor’s 34V High-Fidelity Audio Op Amp Drops Distortion Rate to 0.00003 Percent
LM4562 Sets New Level of Performance For High-End Professional Audio Applications
September 25, 2006 - A new dual, high-fidelity audio operational amplifier from National Semiconductor Corporation (NYSE:NSM) practically eliminates distortion, with total harmonic distortion plus noise (THD+N) of 0.00003 percent. The LM4562 amplifier joins the recently introduced LM4702 high-voltage stereo driver as a member of National’s new high-performance audio family.
National’s LM4562 sets a new level of performance with its remarkably low distortion, low noise, high speed, wide operating voltage and high output drive. These features make the op amp well-suited for professional and high-end audio applications such as audio/visual (AV) receivers, preamplifiers and mixers, as well as a range of 34V medical imaging and industrial applications.
The LM4562 has a unique design, combining a high-speed, 6 MHz, unity-gain bandwidth operational amplifier with a new, proprietary stereo audio power amplifier that offers all the key specifications needed for superior audio performance and signal conditioning. The op amp features low-input noise density of 2.7 nV/sqrt Hz at 217 Hz, a 1/f noise corner of 60 Hz and 600-Ohm output drive. To ensure that the most challenging high loads are driven without any noise compromise, the LM4562 has a slew rate of 20 V/us and a 56 MHz gain bandwidth. The dual op amp is available in 8-lead SOIC, dual in-line (DIP) and metal can packages. Single and quad versions of the op amp will be available in early 2007.
Key Technical Features and Benefits
The LM4562 is unity-gain stable over a wide supply range of plus or minus 2.5V to 17V and has output current capability of 45 mA. Over this supply range, the LM4562’s input circuitry maintains common-mode and power-supply rejection rates (PSRR) of more than 108 db and a typical low input bias current of 10 nA. The op amp offers a full audio dynamic range maximized with an output stage. This output stage can swing to within 1V of either power supply voltage when driving 2-kiloOhm loads or to within 1.5V when driving 600-Ohm loads.
The op amp retains its performance levels while driving capacitive loads as high as 100 pF. Its transparent, no-click, no-pop mute function forces the amplifier output into a quiescent state, saving power. It also features thermal shutdown and output short-circuit protection.
Pricing and Availability
Available now in the standard SOIC package, the LM4562 is priced at $1.99 each. The DIP package is priced at $2.29 each and the metal can package is priced at $7.99 each. All prices are in 1,000-unit quantities. Lead-free package options that are compliant with the European Restriction on the use of Certain Hazardous Substances (RoHS) directive are also available. More information, easy-to-order samples and evaluation boards are available at http://www.national.com/pf/LM/LM4562.html.
National Semiconductor published a press release today, http://www.national.com/news/item/0,1735,1195,00.html
National Semiconductor’s 34V High-Fidelity Audio Op Amp Drops Distortion Rate to 0.00003 Percent
LM4562 Sets New Level of Performance For High-End Professional Audio Applications
September 25, 2006 - A new dual, high-fidelity audio operational amplifier from National Semiconductor Corporation (NYSE:NSM) practically eliminates distortion, with total harmonic distortion plus noise (THD+N) of 0.00003 percent. The LM4562 amplifier joins the recently introduced LM4702 high-voltage stereo driver as a member of National’s new high-performance audio family.
National’s LM4562 sets a new level of performance with its remarkably low distortion, low noise, high speed, wide operating voltage and high output drive. These features make the op amp well-suited for professional and high-end audio applications such as audio/visual (AV) receivers, preamplifiers and mixers, as well as a range of 34V medical imaging and industrial applications.
The LM4562 has a unique design, combining a high-speed, 6 MHz, unity-gain bandwidth operational amplifier with a new, proprietary stereo audio power amplifier that offers all the key specifications needed for superior audio performance and signal conditioning. The op amp features low-input noise density of 2.7 nV/sqrt Hz at 217 Hz, a 1/f noise corner of 60 Hz and 600-Ohm output drive. To ensure that the most challenging high loads are driven without any noise compromise, the LM4562 has a slew rate of 20 V/us and a 56 MHz gain bandwidth. The dual op amp is available in 8-lead SOIC, dual in-line (DIP) and metal can packages. Single and quad versions of the op amp will be available in early 2007.
Key Technical Features and Benefits
The LM4562 is unity-gain stable over a wide supply range of plus or minus 2.5V to 17V and has output current capability of 45 mA. Over this supply range, the LM4562’s input circuitry maintains common-mode and power-supply rejection rates (PSRR) of more than 108 db and a typical low input bias current of 10 nA. The op amp offers a full audio dynamic range maximized with an output stage. This output stage can swing to within 1V of either power supply voltage when driving 2-kiloOhm loads or to within 1.5V when driving 600-Ohm loads.
The op amp retains its performance levels while driving capacitive loads as high as 100 pF. Its transparent, no-click, no-pop mute function forces the amplifier output into a quiescent state, saving power. It also features thermal shutdown and output short-circuit protection.
Pricing and Availability
Available now in the standard SOIC package, the LM4562 is priced at $1.99 each. The DIP package is priced at $2.29 each and the metal can package is priced at $7.99 each. All prices are in 1,000-unit quantities. Lead-free package options that are compliant with the European Restriction on the use of Certain Hazardous Substances (RoHS) directive are also available. More information, easy-to-order samples and evaluation boards are available at http://www.national.com/pf/LM/LM4562.html.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.