2. amps-preamps
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Tube preamp troubleshooting

Hi everyone,

As I posted on the general forum, I have had a tough run of bad luck and mismatches with tube equipment. I just purchased a used Modwright LS100 for the following system:

1. CD - Marantz SA8004
2. Amp - McCormack DNA-125

I had been running it over the last few days with the pre-out on a Musical Fidelity M3i with no problems. Upon putting the Modwright in the system, I got some fairly loud tube rush from both channels. The right channel is a constant sound and the left channel seems to have some variation (much like the sound of wind over a microphone). Turning the volume knob up doesn't cause much change in the right channel. In the left, it makes the sound increase, crackle, whoosh louder while the knob is turning, but once the knob stops it returns to the same level of intermittent tube rush.

I assume the first step is to order new tubes, but if anyone has a suggestion of something else I might try, I'd appreciate it. The Modwright sounds quite good, but the tube rush is a major problem.

Thanks,
Scott
smrex13
abucktwoeighty's avatar
abucktwoeighty
1,034 posts
 
I thought the same thing. Wait until your new tubes arrive before you do anything drastic. When I put the new tubes in, everything was good.
abucktwoeighty's avatar
abucktwoeighty
1,034 posts
 
Now that I think about it, I was ready to ditch the LS100 and get a pass labs preamp. Was close to buying one when my tubes arrived. Put them in, and all was well. The LS100 is an excellent piece.
smrex13 OP
423 posts
 
Well, just tried to power it down, and now the power button makes the balance control activate, but the unit won't power down. Clearly a defective preamp. Will be sending it back.
Post removed 
jmcgrogan2's avatar
jmcgrogan2
6,346 posts
 
Cdrc, you are entitled to your opinion, but I do think you ramble on a bit too much about euphonic colorations. Especially for someone using Kubala Sosna cables and cords.

So you choose to hard wire your euphonic colorations as opposed to those who choose to use electronics to tailor the sound to their taste. In the end, euphonic colorations are euphonic colorations, no matter how one wishes to install them into their system.
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