Four Channel B1
I posted this in another thread, but that one doesn't have as much "traffic" as this one. So forgive my double post
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Four Channel B1 Post #6
Recently I have become a big fan of active crossovers and have been using a ganged pot after a modded Behringer DCX (crossover) and prior to 4 channels of amplification.
I saw reference to the B2 buffer, but I guess that is not being released for DIY. So I made a breadboard version of the B1 buffer (2 channel version at this point).
So currently the power supply on the B1 buffer drives two channels and it uses a power adapter from an old HP printer (18volt and 1.1 amp). I read that the B1 circuit only draws about 20 mA.
I would like to use the current Power Supply section from the B1 and have it run a total of 4 channels. My plan is simply to use the current Power Supply section and have it drive the additional circuitry for the extra channels. Although I might increase the R1 resistor from 3W to 5W.
I guess my question is whether a single B1 power supply is sufficient to drive the extra channels?
Again, I am pleased with the sound of my 2 channel B1 buffer (with the "stock" power supply). I am happy with the power supply as it is.
Cheers!
I posted this in another thread, but that one doesn't have as much "traffic" as this one. So forgive my double post
.........................................................
Four Channel B1 Post #6
Recently I have become a big fan of active crossovers and have been using a ganged pot after a modded Behringer DCX (crossover) and prior to 4 channels of amplification.
I saw reference to the B2 buffer, but I guess that is not being released for DIY. So I made a breadboard version of the B1 buffer (2 channel version at this point).
So currently the power supply on the B1 buffer drives two channels and it uses a power adapter from an old HP printer (18volt and 1.1 amp). I read that the B1 circuit only draws about 20 mA.
I would like to use the current Power Supply section from the B1 and have it run a total of 4 channels. My plan is simply to use the current Power Supply section and have it drive the additional circuitry for the extra channels. Although I might increase the R1 resistor from 3W to 5W.
I guess my question is whether a single B1 power supply is sufficient to drive the extra channels?
Again, I am pleased with the sound of my 2 channel B1 buffer (with the "stock" power supply). I am happy with the power supply as it is.
Cheers!
Im sure others could do much more advanced stuff
But this little heater supply from Broskie is nice, and cheap
And he have made it special with 25V to suit another of his own design
I first thought its 25V would be high, and in need of adjusting, which probably would be easy
But it now seems that 25V would be perfectly fine
It only needs a small trafo
With a 2x 18V volt even two supply modules could be used, making it double mono
As it is a heater supply fore tubes it can put out some power, around 2.5A
But this little heater supply from Broskie is nice, and cheap
And he have made it special with 25V to suit another of his own design
I first thought its 25V would be high, and in need of adjusting, which probably would be easy
But it now seems that 25V would be perfectly fine
It only needs a small trafo
With a 2x 18V volt even two supply modules could be used, making it double mono
As it is a heater supply fore tubes it can put out some power, around 2.5A
Attachments
Re: Four Channel B1
I'm no expert, but it appears that you should be fine driving four channels. Just make sure that C2 is at least, say 2000uF, and that your AC/DC converter is capable of supplying more than 80mA. I'm not sure why R1 is specced at 3W (maybe someone else could help us), but bumping it to 5W couldn't hurt.
-j
PrestonTom said:
I'm no expert, but it appears that you should be fine driving four channels. Just make sure that C2 is at least, say 2000uF, and that your AC/DC converter is capable of supplying more than 80mA. I'm not sure why R1 is specced at 3W (maybe someone else could help us), but bumping it to 5W couldn't hurt.
-j
Re: Re: Four Channel B1
Diomedian, thanks for your comments.
I have followed the original design, so both C1 and C2 are 15,000 uF. The converter is labelled as 1.1 amp.
I am being cautious about this, since I do not have much experience with power supplies, especially with circuits that draw so little current.
Thanks
Diomedian said:
Diomedian, thanks for your comments.
I have followed the original design, so both C1 and C2 are 15,000 uF. The converter is labelled as 1.1 amp.
I am being cautious about this, since I do not have much experience with power supplies, especially with circuits that draw so little current.
Thanks
PrestonTom said:
Well, Thats what I would consider to use
Its cheap and simple, with both smoothing and regulation, all in one, its not always so
I dont fell good about those PC related things, might be ok though
Other than the possible advantage of having an outboard supply
Though recommended optimal supply voltage rating might be a matter of distortion figures
But with those huge 15.000uf caps your 1A supply might be ok, I guess
If it works, it works
Mind you, Im no expert, it was only a suggestion
Altered pots--altered sound?
I did some alterations to preamplifier and now it sounds somewhat muffled and not as clear.
First, I changed my pots from two reverse log taper to one stereo pot. Same brand and I thought same specifications as before.
Old pots: http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=KB2531S28-ND
New pot: http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=KKU1031S28-ND
Second, I switched from simple toggle switch to this switch:
new: http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=GH7102-ND
Third, removed LED.
Last, I twisted the wires leading to the pots into groups of three.
Before I try to undo each of the above, does anyone have a suggestion of what is most likely the cause of the problem?
Thanks, Timothy
I did some alterations to preamplifier and now it sounds somewhat muffled and not as clear.
First, I changed my pots from two reverse log taper to one stereo pot. Same brand and I thought same specifications as before.
Old pots: http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=KB2531S28-ND
New pot: http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=KKU1031S28-ND
Second, I switched from simple toggle switch to this switch:
new: http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=GH7102-ND
Third, removed LED.
Last, I twisted the wires leading to the pots into groups of three.
Before I try to undo each of the above, does anyone have a suggestion of what is most likely the cause of the problem?
Thanks, Timothy
DougL said:
I posted the wrong link to the new pot, it is indeed 50K. Link should be:
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=KKA5031S28-ND
I will first attempt to untwist these wires. Then I will put a Nelson authorized blue LED back!
Timothy
I don't like the idea of twisting all the wires together, at the pot.
So untwist them first.
Better still only do it for one channel and compare between the two.
It would be nice if you had a switch box, placed between the cd player and the preamp.
If you can manage to do this, then use only one channel out of the cd player run this to the switch box which has 2 rca cable coming out the other end and into the the preamp (L + R channel).
Put on your favourite song and switch away.
Also, why did you remove the LED?
So untwist them first.
Better still only do it for one channel and compare between the two.
It would be nice if you had a switch box, placed between the cd player and the preamp.
If you can manage to do this, then use only one channel out of the cd player run this to the switch box which has 2 rca cable coming out the other end and into the the preamp (L + R channel).
Put on your favourite song and switch away.
Also, why did you remove the LED?
thanh1973 said:
If using stereo 50K versus two 25K pots does not seem to be the issue, nor the different switch, I'll first try untwisting wires to pots. As per the prior suggestion I'll do this for one channel and see if there is any difference.
I removed the LED as I did not want to drill out another hole in the chassis faceplate and have not figured out a clever means to putting it behind one of the knobs. With my first attempt at any build, I wanted some confirmation the preamp was indeed being powered, so elected to initially include the LED. I had some various AC/DC around so wanted to see what would power the unit. I did find that 12V was fine, but I notice no additional noise when using 18V or 24V. Using a 10V failed to even light the LED.
Thanks for all the feedback and help thus far from the group.
Timothy
