This is an absolutely great forum. You can give your opinion on all kinds of things ( mostly related to audio I guess!) AND listen to what other feel about similar things.
However be cautious when you feel like this ... "....opa134 series is a gem. I havent used ad's but have heard quite a many praises about them...." .
The bottom line is that you can't have a real opinion about such things unless you have tried it yourself. What works well in one case may not work as well for you . You need to try it out. It takes time sometimes to get the parts you want to try. So wait for that before you really believe in it.
Some " truths" 'might' not apply to your application ! You can see similar examples scattered all over this forum.
Most importantly you should have fun doing what you want to do.
Cheers.
However be cautious when you feel like this ... "....opa134 series is a gem. I havent used ad's but have heard quite a many praises about them...." .
The bottom line is that you can't have a real opinion about such things unless you have tried it yourself. What works well in one case may not work as well for you . You need to try it out. It takes time sometimes to get the parts you want to try. So wait for that before you really believe in it.
Some " truths" 'might' not apply to your application ! You can see similar examples scattered all over this forum.
Most importantly you should have fun doing what you want to do.
Cheers.
I think you should have a look at the thread dealing with power supply regulators on this forum. I remember seeing a spectrum of the trash on the battery supply in the presence of a music signal.
I can't remember the levels but it looked quite significant .
Maybe the difference between a fantastic sounding and a good sound amp (?).
A good PSRR probably is always welcome . In some cases it need not be very high I guess.
I've got a NE5532 in my mic preamp. It works fine at 1.2, 2 and 65 gains. Though I cannot tell much about the quality as it is used on a microphone.
I've spent a lot of time comparing opamps. TI has nice devices, like the OPA604 and 134.
I have also found many interesting things from Analog devices.
AD797 is still my favorite on paper, but it seems to be not recommended for gains below 5. But maybe it could help me keeping the power amplifier's gain low, and keep feedback resistors at low values, which gives better results.
I have also found the AD745, the ADA 4841-1 (cheaper than the others, strangely), the AD746, the AD795, and the AD8099.
What a mess, they all compare very well !
I doubt there will be any dropout with a preamplifier. Maybe with a power amp, but not a preamp that draws a few mA. Decoupling is always welcome I think
Ashok,
I saw that thread a long while ago, and yes there is some chemical noise in the power provision from a battery, in theory the headroom (deliverable current) is huge - inpractice its still pretty large...
With a regulator, you have a fixed current headroom, beyond which you end up in potential difficulties, and sonic nasties
Much of the trash is neatly dealt with by a few thousand uF bypassing, and you retain the potential current delivery - battery supplies require design too (and that doesn't include regulation in my book). I find regulators to sound 'forced' and flattened by comparison to a good battery supply.
PSRR is welcome where you have a poor initial PSU (lots of ripple), when your PSRR is lower than the ripple from your PSU, it's basically doing nowt anyway.
Just my View
Owen
one of those lesser God's noises.
oh God when will these noises about unknown noises in this great forum cease.
some talk of noise of m/f res,costlier m/f res,less noise etc etc., some talk bout audio grade cable noises,costlier sounds good(as if it has a built in fm)..........
oh please,leave these noises alone in there solitude.they dont disturb u then y do u disturb them!
OWEN,
i have read many of your posts,and this is not what i thought could be posted by u.
noise from batteries....
TNT audio had some articles about power supply design and also compared with batteries.... The measurements on the batteries showed lots of noise, but it was mostly 50hz.... they ended up saing that it could also be noise from the measurement setup
If there is noise in batteries it will most likely not be 50Hz....
Batteries do need a lot of capacitance due to the hihgish internal resistance. Hiraga concluded (about 20 years ago?) that the improvents in sound quality of his "The monster" amp gained very little in sound quality at >1F
Thomas
TNT audio had some articles about power supply design and also compared with batteries.... The measurements on the batteries showed lots of noise, but it was mostly 50hz.... they ended up saing that it could also be noise from the measurement setup
If there is noise in batteries it will most likely not be 50Hz....
Batteries do need a lot of capacitance due to the hihgish internal resistance. Hiraga concluded (about 20 years ago?) that the improvents in sound quality of his "The monster" amp gained very little in sound quality at >1F
Thomas
What do you mean there ? Good or not good ?? (lol, my english is not as good as yours I assume
)I've looked at the AD797 datasheet, they recommend Ceramic 100nf in parallel with Tantalum 22µf for bypassing. These are high-end components, but maybe an even larger decoupling, such as 470µf in parallel with those caps could help filtering HF rubbish. I've also seen a preamp that used a 1000nH self before the caps, probably to furthermore filter the HF noise from the regs. It shouldn't degrade the sound if large caps are used after won't it ? ( a preamp should only draw a few mA)
Re: noise from batteries....
Try to be more precise when ridiculing others ...
There was one (1) noise plot in the TNT series that exhibited 50Hz breakthrough. This was the noise plot of a particular regulator, and later the source of the breakthrough was identified (though a new noise spectrum was never recorded since not relevant).
The batteries measured by TNT featured no 50Hz components whatsoever. However, the NiCd rechargeable had very suspect behaviour.
There is a plot of batteries with 50Hz and harmonics on TNT, yes, but that plot was measured by Andy here and donated to TNT for publication as is.
http://www.tnt-audio.com/clinica/regulators_noise4_e.html
ThomasS said:TNT audio had some articles about power supply design and also compared with batteries.... The measurements on the batteries showed lots of noise, but it was mostly 50hz.... they ended up saing that it could also be noise from the measurement setup
Try to be more precise when ridiculing others ...
There was one (1) noise plot in the TNT series that exhibited 50Hz breakthrough. This was the noise plot of a particular regulator, and later the source of the breakthrough was identified (though a new noise spectrum was never recorded since not relevant).
The batteries measured by TNT featured no 50Hz components whatsoever. However, the NiCd rechargeable had very suspect behaviour.
There is a plot of batteries with 50Hz and harmonics on TNT, yes, but that plot was measured by Andy here and donated to TNT for publication as is.
http://www.tnt-audio.com/clinica/regulators_noise4_e.html
Very nice article !
I'll try to get samples of OPA637/OPA134 if I can, otherwise, OPA637 is way too expensive for the little difference.
I already have to get AD797, and maybe AD745, AD8099 and ADA4841-1
I already see the implementation of my future preamp :
-1st stage global regulation using LM317/337 taken from the amp's PSU
-2d stage using 15V / 5V regulators I haven't chosen yet
-Optional switch allowing to use either an external PSU (battery) or the 2d regulation stage
- maybe 3d stage regulation next to the IC
2d regulation stage will be implemented separately for each preamp channel next to the IC.
Is it a good idea ?
I'll try to get samples of OPA637/OPA134 if I can, otherwise, OPA637 is way too expensive for the little difference.
I already have to get AD797, and maybe AD745, AD8099 and ADA4841-1
I already see the implementation of my future preamp :
-1st stage global regulation using LM317/337 taken from the amp's PSU
-2d stage using 15V / 5V regulators I haven't chosen yet
-Optional switch allowing to use either an external PSU (battery) or the 2d regulation stage
- maybe 3d stage regulation next to the IC
2d regulation stage will be implemented separately for each preamp channel next to the IC.
Is it a good idea ?
more on noise
Sorry - no offence intented!
I meant lead acid batteries...
The problem with the (otherwise excelent) TNT article on PSU is only that specific graph showing the lead acid measurement - it should never have been published in the first place (being obviously flawed) - and more importantly - the should remove the graph or make a clear notice of the problem...
As it is - people keep refering to it
I would like to see the measurement repeated - any references out there?
My gainclone sound superb on batteries - much quiter than with a simple un-regulated pi-supply (not that it really says a lot about the noise compared to those regulated supply's in the TNT article)
Thomas
Sorry - no offence intented!
I meant lead acid batteries...
The problem with the (otherwise excelent) TNT article on PSU is only that specific graph showing the lead acid measurement - it should never have been published in the first place (being obviously flawed) - and more importantly - the should remove the graph or make a clear notice of the problem...
As it is - people keep refering to it
I would like to see the measurement repeated - any references out there?
My gainclone sound superb on batteries - much quiter than with a simple un-regulated pi-supply (not that it really says a lot about the noise compared to those regulated supply's in the TNT article)
Thomas
same case here
.i run tda1554 and tda8563 in my car directly from battery and they r damn quite.so much so that i have to put my ears into woofer cone to listen if they r on or off(though led indicator shows them on
)so where comes the acid noise
.god knows who created these noises that are audible to people blessed with 'audio grade' ears that we mere mortals are not.
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