Which buffer to choose

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Kjeldsen

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Joined 2003
kjeldsensforbindelser.dk
#1
I'm really no good at circuits, so need help to choose simpel buffer. I have some TPA3118 and pascal spro2 that need buffers. I have found some but need advice. Noise must be very low, easy to implement, volume nice to have but not really needed. Strong enough to drive my spro2 modules, single ended, I don't need balanced input

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#3
Consider this bBuffer

In this link, if it works, is an LME 49600 buffer board sold on Ebay. It uses a DC servo and makes a great headphone amplifier or general buffer stage. With the resistors as labeled on the board, the gain is about 2. However, if you are interested, I can provide a photo to label the resistors you can change to increase the gain. I have several of these boards and they sound great. I use one set for a gain of 10 for connecting my portable digital player to my Yamaha receiver which is a bit short on gain. The buffer output ensures the bass frequencies are not reduced.

LME49720HA LME49600 Headphone Amp Preamp Audio Signal Amplifier Buffer Board LME49720HA + LME49600 Headphone Amp Pre-amp Audio Signal Amplifier Buffer Board 699934972165 | eBay
 
#10
You can also change out the gain resistors on one of these preampmodules. 5k will give you unity gain.
LEORY DC 9 24V AC 8 16V NE5532 Audio OP AMP Stable Microphone Preamps Pre Amplifier Board|Operational Amplifier Chips| - AliExpress

I do however experience a bit of noise with these modules. I'm going to run them from a separate power supply to see if it makes any difference, just to know if they are any good.
I also have need of a decent buffer stage with no gain. After doing research I have decided I am going to attempt to build a Nelson's Pass B1 on solder breadboard.
I also found this goldmine of information regarding opamps and buffer/preamp stages.
Audio Designs With Opamps

It's not hard to solder your own buffer using an opamp and some resistors.
 
#12
After reading the articles on opamp buffers that I mentioned in my previous comment, I have decided I am setting out to design my own buffer.

It seems like this is the perfect project for beginners. I have plenty experience with the practical side of electronics. Up to this point I have only build pcb kits.
A simple zero gain buffer is a matter of an opamp and just a few components and a way of powering them, so that will be my first goal in designing a circuit and pcb layout.

After that I think it would be great to add low and high pass filter version so I can basically use any of these TPA3116d2 or TPA3118 amps as a subwoofer amp or a biamped 2-way.



Kjeldsen said:
Have read that one. It's when I read more I get confused. Then people add snubbers, capacitors to gnd for stability and less noise. Basically for now, I just would like to see the ultimate simple NE5532/4 buffer.

I have ordered this for. Its with gain though

2Pcs Preamplifier NE5532 Stereo Audio Amplifier PCB Board DIY for 4558 LM833 | eBay
Click to expand...

I can relate to that. The problem I'm often facing is that I'm diving deep into very specific audio stuff while lacking knowledge about the basics like decoupling capacitors and snubbers. The trick here is often to zoom out and take the time to study the boring basic stuff first. There are a lot of useful articles on that website for electronics basics aswel.

So far I've always been building kits or modding stuff according to other peoples articles. But lately I've been digging more into the basics of electronics. I must say that all of a sudden things start to make a lot more sense.
 
#16
Hmm, at those prices I´d rather want to know what I´m getting.
Did you consider the offerings here in the forums (XRK, EUVL, Neurochrome etc.)
Not sure if X´s universal buffer can be had populated from the Etsy-page but you can always ask.
BTSB Puffer SE/Bal zu SE/Bal Puffer | Etsy
Or look around for gerber and populate yourself or see if somebody will sell a buffer to you!? (swap meet or PM)
Here for example:
Line level buffer: discrete or ICs based?
Post #128

There´s gotta be quite a few designs around here that have accumulated over the decades.
 
#17
Thanks. I know the neurochrome buffer. But it's 150$, and the chinese are15-20$. Thats quite a difference. The Etsy buffer I have also seen, but I'm not happy with smt soldering, eventhough I have done it several years ago.

I have tried european searches, but only found Eltim, which is out of stock. Not many selling just ready made buffers.
 
#18
but I'm not happy with smt soldering
Click to expand...
you could have asked X if he eventually has a prototype lying around but shipping would be a substantial part of the cost.
He also offers a through-hole version BTW, if you still consider populating yourself.

In the other thread above you could send Oleg a PM and ask if he has populated boards left. Looks like he ordered a few.

I´ve looked at audiophonics and found a couple of things:
Search - Audiophonics
This would probably work if you set gain of 1 (the latter could make most little preamp PCBs usable).
AUDIOPHONICS Module Buffer Stereo AOP OP275 V2.2 - Audiophonics
This could be nice if you want volume control (again you will have to "reset" the gain):
Stereo Line preamplifier AOP 5532 50K Potentiometer - Audiophonics
I have one of these but am not sure how well it buffers; I reckon it should though. Still lying in a box somewhere...:
WONDOM AA-AB41116 PT2259 Digital stereo Audio Volume control module rotary encoder - Audiophonics

As said, maybe look for little preamp boards where you would simply set the gain to 1.
Choices should be much bigger.
 
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#20
Thanks I will have a look. The small through hole pcb I have seen, but Im afraid they somehow are too simple, but it just gut feeling, and not based on knowledge. Audiophonics only have buffers with 100 to 600 ohm Zout as far as I can see. 100 is ok, but 600 is too high for the low Zin on my Pascal moduler.

The small PCB version might be a good option to learn a bit.
 
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