GC buffer question

dsavitsk · 8th March 2005, 05:04 PM

I am looking to put a very simple buffer in front of my BrianGT GC (and after a Noble 50K pot). I came up with the following design (mostly based on the BUF634 datasheet and tangent's rail splitter.) Could anybody comment on whether this will work, and whether there are any obvious changes I should make. (I happen to have the BUF634's around, so I'd rather not swap them out unless they are a terrible choice.)

Thanks,

-d

Nuuk · 9th March 2005, 08:07 AM

Do you want a really simple buffer? How about this?

Full details here

dsavitsk · 9th March 2005, 04:28 PM

Hmmm. That looks interesting too, and I might try it. I've not used discrete transistors before, so could you be specific about which direction they are facing in the schematic - that is, which pin is which?
Edit: The BC547 has the pin diagram on it's data sheet where the little arrow is pin 3

Also, while the parts are all cheap, the parts for the BUF634 version are free as I have them, so I am still wondering if anyone has any comments regarding the above design. Is it worth trying?

-d

Shoog · 9th March 2005, 05:19 PM

I can vouch for the quality of the buffer which Nuuk mentioned. I have one amp using it, and another using the OPA627 buffer. They sound about the same, though the descrete buffer might just have the edge. The sound of the buffer can be tuned by altering the 120R resistor at the bottom. This allows the use of just about any transistors (mine are out of old PC power supplies).

Shoog

Nuuk · 9th March 2005, 05:28 PM

Quote:

so could you be specific about which direction they are facing in the schematic - that is, which pin is which?

Have a look at this

steenoe · 9th March 2005, 05:35 PM

Quote:

be specific about which direction they are facing in the schematic

They face the same way. You have to keep track of the arrow on the transistors and compare to the datasheet. Quite confusing, I agree.

Steen.

dsavitsk · 9th March 2005, 10:28 PM

Any reason that I can't use BC547B's rather than the listed BC547C (data sheet is here http://rocky.digikey.com/WebLib/On-S...Data/BC546.pdf) There is some difference, but I don't know enough to interpret it.

-d

Nuuk · 10th March 2005, 08:04 AM

Quote:

Any reason that I can't use BC547B's rather than the listed BC547C

No! If you read the article you will see that it is OK to try almost any type of NPN transistor.

From the preamp article on Decibel Dungeon (for those that would like to read it!)

Quote:

All three transistors are NPN types and choice is not too critical.

frdchang · 10th March 2005, 08:49 AM

it seems like decibel dragon used another powersupply for his buffers.

it was not clear if he used a different powersupply for the transistor based buffer.

what is the motivation of using different power supplies? (does it sound better?)

Nuuk · 10th March 2005, 10:16 AM

Quote:

it seems like decibel dragon used another powersupply for his buffers.

Different to what? If you can be a bit more precise with you question, I'll try and answer you.

9th March 2005, 08:07 AM	#2
Nuuk diyAudio Member Join Date: Feb 2003 Location: Somerset, SW England	Do you want a really simple buffer? How about this? Full details here __________________ The truth need not be veiled, for it veils itself from the eyes of the ignorant.

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9th March 2005, 04:28 PM	#3
dsavitsk diyAudio Member Join Date: Jan 2005 Location: Chicago	Hmmm. That looks interesting too, and I might try it. I've not used discrete transistors before, so could you be specific about which direction they are facing in the schematic - that is, which pin is which? Edit: The BC547 has the pin diagram on it's data sheet where the little arrow is pin 3 Also, while the parts are all cheap, the parts for the BUF634 version are free as I have them, so I am still wondering if anyone has any comments regarding the above design. Is it worth trying? -d

9th March 2005, 05:19 PM	#4
Shoog diyAudio Member Join Date: Aug 2002 Location: Eire	I can vouch for the quality of the buffer which Nuuk mentioned. I have one amp using it, and another using the OPA627 buffer. They sound about the same, though the descrete buffer might just have the edge. The sound of the buffer can be tuned by altering the 120R resistor at the bottom. This allows the use of just about any transistors (mine are out of old PC power supplies). Shoog

9th March 2005, 10:28 PM	#7
dsavitsk diyAudio Member Join Date: Jan 2005 Location: Chicago	Any reason that I can't use BC547B's rather than the listed BC547C (data sheet is here http://rocky.digikey.com/WebLib/On-S...Data/BC546.pdf) There is some difference, but I don't know enough to interpret it. -d

10th March 2005, 08:49 AM	#9
frdchang diyAudio Member Join Date: Feb 2005 Location: Berkeley	it seems like decibel dragon used another powersupply for his buffers. it was not clear if he used a different powersupply for the transistor based buffer. what is the motivation of using different power supplies? (does it sound better?)

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