Active Bi-amp PCB

I used common base emitter current source, transistor with voltage reference at base. No packed regulator.
 
Ok, Thanks for the info. I will try LM338 this time, I think snubber should take care of impedance of LM338. Worst case if I dont like it, i anyway have option of pulling it out from board and shorting input and output pins.
 
I am not discouraging you anyway. Just putting out problem which I faced so that you are aware of it and can take care in your design.

Good luck!
 
afaik, regulated supply improves sound quality this is what I have read from other forums about regulated PS.

True, this theory works well with low voltage swing high gain amps (preamps)well. But power amps are a different sort of beasts and they are more happy with a raw unregulated supply most of the times, provided you have a well designed wiring pattern, layout and earthing AFAIK. The theory behind it is that huge bass transients often need energy inputs which cannot be supplied by the power supply (Trafo and rectifier) alone. This is usually compensated by the big reservoir caps . Moreover, chip amps are designed to perform good over a big voltage 'bandwidth'. So, in my opinion, a fair amount of reservoir caps and good layout will do more good than a regulator in this case. I am no authority in power amp design and everything aforesaid is said from my experience in amp building only. Again, in my opinion, better we trust a discrete amp for the low frequency part. chip amps perform stunningly well with high frequencies but inferior in bass reproduction owing to the quasi complimentary output stage. LM 3868 is no exemption, I think but not sure.
 
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Hi Aniruddh,

Its good you are in Pune, there are many DIYers in Pune like OMISHRA...and if you search this forum sachin,sandeep,rohitmusic and jls001 from mumbai and...many others are pioneers in this field ....my request is to PM them and get in touch with them....in this way we can learn many things from each other....

Actually they have built preamps, poweramps and speakers , so you can have fare idea what they are talking....

Hope you have fruitful sessions with them....

cheers
dheerajin
 
True, this theory works well with low voltage swing high gain amps (preamps)well. But power amps are a different sort of beasts and they are more happy with a raw unregulated supply most of the times, provided you have a well designed wiring pattern, layout and earthing AFAIK. The theory behind it is that huge bass transients often need energy inputs which cannot be supplied by the power supply (Trafo and rectifier) alone. This is usually compensated by the big reservoir caps . Moreover, chip amps are designed to perform good over a big voltage 'bandwidth'. So, in my opinion, a fair amount of reservoir caps and good layout will do more good than a regulator in this case. I am no authority in power amp design and everything aforesaid is said from my experience in amp building only. Again, in my opinion, better we trust a discrete amp for the low frequency part. chip amps perform stunningly well with high frequencies but inferior in bass reproduction owing to the quasi complimentary output stage. LM 3868 is no exemption, I think but not sure.
Many thanks for your valuable suggestions. I have built unregulated power supply amp with lm3886 in past, and faced no issue with bass, sound was clean and powerful with 10000uf caps on each rail.
will get answer to how it sounds with regulated in next few weeks as I already have pcb manufactured for this, and I am in process of soldering the components.
 
Got all components on this PCB working today, Sound is very clean.
No audible hiss or hum even if I put my ears very close to speakers.

I am yet to assemble this in a box and plug it into my speakers, but I tried it with a open woofer and I can say that there should be no problem with bass or low frequencies as it was easily driving this woofer with heavy cone movement.

High frequency amplifier LM1876 sounds very clean and detailed.
I will probably never go back to unregulated powersupply now.
I used Vishay RN55D resistors and vishay roederstein 1837 capacitor and there sure is a great improvement because of these components in the active filter.

I used toroid transformer from torotrans, it has absolutely no vibrations or humming.
Overall, using high grade components in the audio signal path and regulators for all power supply is definitely worth the extra cost.
 
Got all components on this PCB working today, Sound is very clean.
No audible hiss or hum even if I put my ears very close to speakers.

I am yet to assemble this in a box and plug it into my speakers, but I tried it with a open woofer and I can say that there should be no problem with bass or low frequencies as it was easily driving this woofer with heavy cone movement.

High frequency amplifier LM1876 sounds very clean and detailed.
I will probably never go back to unregulated powersupply now.
I used Vishay RN55D resistors and vishay roederstein 1837 capacitor and there sure is a great improvement because of these components in the active filter.

I used toroid transformer from torotrans, it has absolutely no vibrations or humming.
Overall, using high grade components in the audio signal path and regulators for all power supply is definitely worth the extra cost.
Awesome build and my heartiest congratulations!

Wish to see more from you in future.

I really don't understand much about circuits. I was just curious whether the Opamp 5532 upgrade (with a discrete Opamp) may yield better overall sq. Correct me if I am wrong.
 
Thanks Saikat.

I was just curious whether the Opamp 5532 upgrade (with a discrete Opamp) may yield better overall sq. Correct me if I am wrong.
I did online research on best opamp for this purpose long time before, I actually don't remember the exact reason for choosing NE5532, but I remember that I shortlisted 2 opamp, NE5532 and other one was something starting with OPA which were best for audio with low distortion, I think I choose NE5532 because it was easily available and widely used and I am using the same since then.

Not sure if discrete opamp will sound good, will have to try but IMO I don't think it will be worth the effort when good audio opamps are readily available in market, can do this for learning though.
 
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Thanks Saikat.

You are welcome.

I did online research on best opamp for this purpose long time before, I actually don't remember the exact reason for choosing NE5532, but I remember that I shortlisted 2 opamp, NE5532 and other one was something starting with OPA which were best for audio with low distortion, I think I choose NE5532 because it was easily available and widely used and I am using the same since then.

Not sure if discrete opamp will sound good, will have to try but IMO I don't think it will be worth the effort when good audio opamps are readily available in market, can do this for learning though.
I think you are talking about OPA2134. This is a very famous Opamp among many DIYers.

Plenty of users have upgraded from ic based to discrete and found it better. This may be specific for some specific device/design IMHO. I really have no idea whether this upgrade will do justice to your design or not. Maybe a side by side comparison required to distinguish the difference.
 
Will try a simple one on breadboard sometime. It is difficult to get answer to such comparison without trying. Even after trying answer depends on the taste which varies from person to person.
I am not going to modify this now, but surely consider discrete as an option for my next 3 way active project.
 
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