[Mountain-ear]

I have three questions that I'm hoping the esteemed readers of this board can help me with.

1. I replaced the 6N1P tubes in my T8 with Mazda 6CG7 tubes.  I love the sense of depth and dimension they seem to bring, but I don't care for the high end for some reason.  Here's my question.  Can a tube impact just a particular frequency band?  I thought voltage was voltage, but then again, that doesn't explain the difference I hear in the soundstage...

2. If I wanted to compare the 6CG7 with the 6N1P, can run a tube of each type on one channel and then use the mono switches to compare them?  I think so, but I would hate to damage the preamp by doing something dumb.

3. I have an Insight DAC in the small chassis (upgraded by Frank last year).  There is a very subtle hum that I think might be coming from the transformer.  Is that possible, and if so, is it something that I could fix by tightening a screw or something like that?  It isn't particularly annoying.  I actually notice its absence when I turn the DAC off rather than obsessing over it while the DAC is on.  Again, just wanting to err on the side of caution. 

Thanks!

Steve

[martyo]

. I replaced the 6N1P tubes in my T8 with Mazda 6CG7 tubes.  I love the sense of depth and dimension they seem to bring, but I don't care for the high end for some reason.  Here's my question.  Can a tube impact just a particular frequency band?  I thought voltage was voltage, but then again, that doesn't explain the difference I hear in the soundstage..

Absolutely. Any signal tube I have listened to on my gear sounds different. Some are linear, many are not, especially NOS. For instance, many NOS are rolled off at the frequency extremes. Folks sacrafice that for the mids and the depth and dimension you mentioned. Even with our 6CG7s. The Mazdas seem to be a little reticent in the highs from what I gathered from different comments. I bought the NOS RCA clear tops and reticent in the highs they aint. The sibilants are too sibilant for me.  I ended up with the current production EH's in the preamp and the RCA's only in the DAC. Even then there are times I'm not happy with it. But the depth, richness, liquidity, and the increased low end response I'm very happy with. Anyway, yes to your first question.

[rlee8394]

If I wanted to compare the 6CG7 with the 6N1P, can run a tube of each type on one channel and then use the mono switches to compare them?

Yes, exactly. Then use the balance control to pan between the two channels.

Ron

[oneinthepipe]

I have an Insight DAC in the small chassis (upgraded by Frank last year).  There is a very subtle hum that I think might be coming from the transformer. 

Call Frank.