TRL Dude or Joule 150 MKII for Major Pre Upgrade


Thinking of either of these for what I view as a huge pre upgrade in my system. Current system is:

-Celestion A3
-Krell KAV250a (500 wpc/4 ohms).
-Nohr CD-1
-Rotel 995 preamp

I am looking to pickup warmth, depth and much more soundstage. Quality bass is also important to me. I want to keep the Celestions and feel that my current pre is the weakest link. Will also will update my digital source and ss amp down the road.

My thinking is that it will be worth paying up a bit for a higher quality pre that I can grow into.

Also I have a small naive question...with either of these pre amps will the sound difference be that great compared to the Rotel.

Thanks...any comments are appreciated.

-Iggy
iggy7
From the descriptions above, IMO the preamp is off the hook- this is a problem with the power amp.

Also based on these descriptions, its my theory that the amplifier has a problem with noisy rectifiers, which is getting picked up at the input if the source impedance is too high. This is why it is quiet with a shorted input and a 1K resistor, but not with the Dude (which has a relatively high output impedance as the volume control is at the output of the preamp), and likely a few other tube preamps as well.

Noisy rectifiers can be tricky as the commutation noise they produce acts very much like RF (which *is* part of their noise component), in that it can easily get to other parts of the amplifier, and use input connections as an antenna.

However this is only a theory, another possibility is a layout problem where the AC power is somehow too close to the audio input. Either way though- things are pointing at the amp.
grid stop resistor on the 6SN7 of the Aesthetix
OR less likely...
RCA connector on the Aesthetix shorted audio ground to chassis.
Atmasphere,

What about the fact that a Passive Lightspeed pre, cd players and a Bel Canto pre with average to low output impedances caused the same buzz with this amp? Does this rule out the high preamp output impedance theory into the Atlas?
Grannyring,

I have no experience with the Bel Canto but when your passive lightspeed is set to vol = 0 can you measure zero ohms at the output RCA relative to ground, much like the shorting RCA jack you tested? If it's zero ohms then I see no reason why connecting to the lightspeed would be different than shorting the inputs with a shorting RCA.

Recently I spent many hours tackling an interesting project on a previously modified Jolida which gives a buzz similar to what you are hearing. Turns out that power amp uses an AC filament for the gain stage and the center tap of the power transformer is faulty and I had to create an artificial center tap w balancing resistors.

Highly unlikely with your hybrid power amp cos judging from the build ($$$) it would likely use DC filament for the 6SN7s.

Check the input grid stop resistors again, it might be as simple as adding a 1k resistor inline with the signal input to the 6SN7s grid.
Grannyring, that info weakens my theory about the specific malfunction, but strengthens the idea that the amp is at fault. If the amp is in warranty I would return it for repair.