0.75V sensitivity for full output! With all this gain and 94dB speaker why use a active preamp with gain?? Most sources give out more than 2v these days, even phono stages, and the Job I believe is 100kohm input impedance, all this is a perfect match for a passive pre such as the $49 Schitt Sys http://schiit.com/products/sys Then you will not have any hum or noise problems and as a bonus zero colourations that all actives have. Cheers George
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Granny, I agree with George in that the 225 is very "passive friendly" as long as output impedance of source isn't too high. However, its input impedance is 51K.....not 100K. Also, most every source has at least 2V output. What concerns me is the tube preamp. I'm pretty sure Srajean at 6moons said to be very cautious pairing the 225 with a tube preamp. The 225 has no DC protection so any DC leakage goes straight to the speakers! Not good. IMO, the 225's specs SCREAM passive. I'm not going to get into the passive vs active debate hear. That's another topic for another thread. What puzzles me is at 84db, your speakers are not efficient. I would think you would hear LESS hiss and hum beacause of that. That said, I think your active preamp is putting out too much gain for your extremely sensitive, 35db job. Like I said, im FAR from an expert with this here. Just my 2 cents. |
I read one if your other posts again. In it, you say the heatsinks get much hotter the louder you go. I'm wondering if the Job might not like seeing an 84db speaker. I find this hard to believe, though. I've read that the 225 puts out more power than its 125 w/ch spec says. Again, I doubt it. I'm just trying to think of any possible scenario here. |
George knows I have owned, modified, and built LDR passive units so I know them well. I also know they would be a great match with this amp. Problem is I a/b'd my DIY preamp against a Tortuga LDR and my active was just more pleasing. I love George's LDR also. However, this was with a different amp and speakers. It may be time to try that comparison again as things have changed. My preamp does not send out a spec of DC as I measured one, twice, and even a third time over a span of time. I have written Goldmund and hope to fix the issue myself. |
With my volume control at 9 the music is at 80db at 10:30-11 the music plays at 90db or so average weighted C scale. No real noise to speak of until I get to 11AM and then it starts be become loud. If I play my music under 85-90db all is well. If I turn the volume up to 2 or 3 the noise is quite loud through the speakers with no music playing obviously. I hear a moderate buzz combined with loud hissing. The hissing sounds like tube rush, but I hear none of this with all other amps I have paired with my DIY preamp. |
