[Gman]

Which would you use in a circuit to drive low impedance headphones?

 

[aeberbach]

Does it have to be portable?

If the heavy power requirements of the 2009, the need for a heatsink and the fact that it is very hard to get are not a problem, use it! I'm planning on using one in my "passive" preamp, just a current buffer and a stepped attenuator.

 

[Gman]

Wonder why they are so hard to get? Are there no distributors that will deal with the public at large?

 

[zbuddah]

I think the EL 2009's are discountinued. right? or was it the EL 2008's or maybe both....

 

[braillediver]

I finally got thru to Elantec today to request samples since no one seems to sell thier parts. The 1 dealer that has responded qouted 100 piece minimun out of England for the EL2001 with a 4 week lead time.

I'm getting 7 EL2044c's, the sales rep said they can be used as a buffer. I said I wanted to drive 300 ohms at 2 volts. It'll be interesting.

 

[ppl]

If you have the 2009's use them otherwise thay are discontinued as is the 2008. some EL-2009's are still available in some Distrubution chains However. The BUF-634 can be stacked to give 1Amp of Output Current It will take (4) BUF-634's to do that.

aeberbach> If you use the EL-2009 as a passive Active Preamp you will need to Buffer the 2009's input with a JFET source follower so is to prevent the 2009's high input Bias current from causing a dramatic change of DC Offset Voltage with Vol Cont. pos. (See EL-2033 Data sheet on parralell operation)

 

[Gman]

PPL. I was planning on doing the same thing as Aeberbach except I was going to use a buffer to drive a pair of Grados off of the pre out from a NAD integrated amp. Do the BUF634 have enough umph to do the job using only one pair? Also is an input bias current of +_5uA acceptable for this application or will I have to use an opamp to buffer the input to the buffer? Thanks.

 

[aeberbach]

thanks ppl, I'll look at that.

Of course I don't need a preamp until I get my new 300B monoblocks debugged. They sound like ass! It could be because I am trying to use AKG K1000 (120 ohm) on an output transformer wired for 8 ohm, but rigging it with resistors only made distortion worse. New transformers are on the way but I probably still have more debugging to go - but there's no random fault, because they both sound the same.

 

[ppl]

Gman> The BUF-634 should work from the Line Out of your Preamp since a return path For the Input Bias curent of the Buffer is provided by the Preamp. however Problems still can happen if your Preamp is cap coupled and a High value resistor is used to ground. this is an easy test just connect the Buffer to the Pre out and measure the Output of the BUF-634 to see if the DC Voltage is great like over 100 Mv. The BUF 634 operated openloop has about 20-60 Mv of DC offset so this would be normal if you get more then the JFET buffering of the BUF-634's input is needed. as far as Umph gose if your phones are very low impedance < than 100 Ohms i woud use Two or more in Parrallell.

 

[Gman]

Thanks PPL. Have a good one.