[steverii]

Jim,
I am considering building the Castinet strictly for use as a preamp, not as a headphone amp. My amps have a low input impedance of only 10K, but they have 30dB of gain, so the low gain of the Castinet is not a problem. However, looking at the specs of the output trannies shows they have a frequency response of 30Hz to 20kHz at full power. Does the fact that they are not flat down to 20Hz pose a problem when used as a preamp?  Or, since they won't be being used at anything approaching full power (12 watts) will they be flat down to 20Hz when used at the low power required of them when running into the 10K ohm load of my amplifiers?

Thanks
Steve 

[hagtech]

Don't fall for spec numbers.  Not unless you understand them.  That would be at a 12W power rating.   It is NOT how I use the part.  In a CASTANET it is different.  Just check out the specs and oscilloscope photos on my website.

The result is not about the parts used, but of HOW they are used. 

jh

[jrebman]

Jim,

What changes are needed to run this as both a headamp and buffer?  They donm't have to be simultaneous - switchable is fine.

-- Jim

[jrebman]

Never mind -- found the answer.  My cans are HD--650s, so will have to switch to back panel RCAs, or use an adaptor cable.

Cool proje ct -- nice tube .

-- Jim

[hagtech]

I'm actually running my HD600s out of the LO jack, using the HI as a linestage output.

jh

[Theo]

I'm actually running my HD600s out of the LO jack, using the HI as a linestage output.

jh

Are you suggesting it is preferable to plug a high impedance phone to the LO jack?  Is it just personal preference on your part?  I thought the goal of the Castanet design was to match headphone impedance with the HI and LO jacks. 

[hagtech]

You can try whatever you'd like.  I'm always running experiments.

jh