Yogi
Screenwriter
- Joined
- Jul 25, 2002
- Messages
- 1,741
Well finally I was able to integrate a cheap tube pre (2ch) with my SS HT gear. The tube pre was an ASL2004DT integrated with a Denon 3802 hooked to a Proceed AMP 2 for the mains and a B&K Ref7250 for the rest. The speakers are all Vienna acoustics. Out of the box the tube pre sounded fantastic with clean highs and taut bass and a lush midrange. The real kicker came in when last weekend we were watching a DD movie in 2 channel via the tube pre and on a restaurant scene my wife tells me that it looks like the neighbours are having a party since she can hear their music play. I too thought the same until I paused the movie and the neighbours music went away. And we both were wowed by the immense soundstage this preamp was projecting considering that our nearest neighbours home is about 100 feet away. The soundstage was completely three dimensional and extending beyond the physical speakers. I am a tube believer now. No questions.
There is however a problem. Just for kicks I cranked up the preamp all the way and although I couldnt hear any distortion the sound broke up during heavy transients. I listened to some classical scores and when ever there was a drum beat I could hear a crackling noise. I always believed that tubes never go into hard clipping and always distort gracefully so that is something that didnt make sense to me. Whats more baffling is that I hooked up the tube pre directly to my Tape and MD player and I couldnt hear any crackling at any volume level on my preamp. So it baffled me as to why this problem was source dependent. I also tried some higher quality interconnects and while the crackling is reduced to a minimum it still is there on transients. I only have two explanations for that.
1) Either the tubes are defective or highly microphonic.
2) Or there is some kind of impedance mismatch between the source DVD player and my tube preamp. I am thinking its the later as the DVD player is supposed to output 2V RMS and my preamps input impedance is 100K. since I dont know the output impedance of my DVD players analog outs I am only assuming that its in the 10K range, which means my tube pre is seeing almost 20V at its input and on heavy transients some of the internal components are getting saturated leading the the crackling sound. Does that make sense? Any expert opinions on this? I have a set of new tubes ordered so I'll be able to check for tube defect and microphonics tomorrow.
Any input would be greatly appreciated.
There is however a problem. Just for kicks I cranked up the preamp all the way and although I couldnt hear any distortion the sound broke up during heavy transients. I listened to some classical scores and when ever there was a drum beat I could hear a crackling noise. I always believed that tubes never go into hard clipping and always distort gracefully so that is something that didnt make sense to me. Whats more baffling is that I hooked up the tube pre directly to my Tape and MD player and I couldnt hear any crackling at any volume level on my preamp. So it baffled me as to why this problem was source dependent. I also tried some higher quality interconnects and while the crackling is reduced to a minimum it still is there on transients. I only have two explanations for that.
1) Either the tubes are defective or highly microphonic.
2) Or there is some kind of impedance mismatch between the source DVD player and my tube preamp. I am thinking its the later as the DVD player is supposed to output 2V RMS and my preamps input impedance is 100K. since I dont know the output impedance of my DVD players analog outs I am only assuming that its in the 10K range, which means my tube pre is seeing almost 20V at its input and on heavy transients some of the internal components are getting saturated leading the the crackling sound. Does that make sense? Any expert opinions on this? I have a set of new tubes ordered so I'll be able to check for tube defect and microphonics tomorrow.
Any input would be greatly appreciated.