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.


Showing 27 responses by grannyring

I have owned Joule preamps in the past including the 100 MKlll. I like the Joule sound and he makes fine preamps for sure. I have not heard the 150 however. I know the Joule would be a nice improvement over your Rotel.

I have owned the Dude for several years now and can say it will deliver the things you are looking for to a greater degree then the Joule. The Dude is a champ at bass and soundstage plus in many other ways.

The Dude will cost $4,000 new and you can find used 150's for under $3,000. Is the Dude worth another $1,000 - $1500?
If you can stretch up to the Dude with your cash, then yes it is. At least is/was for me :-)

Both offer a significant improvement over your Rotel
Yes TRL has been building great gear for decades an my Dude has been flawless in sound and performance since day one! Both Dudes I have owned.

Paul answers his phone and will always get back right away and help. I must say this is not true of all small "one man" companies. I have still not heard back from Roger at Music Reference and I emailed/called to actually buy his amps - RM10.I decided to buy another amp now. He is one example and unfortunately I know of many others in this business. Paul will respond to customers.
I really wanted to try a RM10 and asked about buying two in mono block form. It has now been 5 days and no answer. This scares me. Oh well, I bet it is an awesome amp based on many comments by owners.

The Dude photo on the website is old and the old style. The new Dude can be custom made with dual volume or one volume knob. Paul will build it as you like. Mine has one volume knob and 4 - 6sn7 tubes instead of two for slightly more gain. This 4 - 6sn7 design option is not needed for the vast majority of folks, but worked well with my power hungry Soundlab speakers.

The Dude is not small, but a 70 pound beast . The circuit is Paul's and really simple but robust beyond any other pre I have seen.
I would ask Paul if he would build you one like that. Only he can answer that question.
The Dude as an output impedance of around 5k ohms. I am having the same noise problem in my system with an Aesthetix Atlas hybrid amp and my Dude preamp. The Atlas has both xlr and RCA inputs however. I get a buzz with both the Dude and a passive preamp -
Lightspeed Attenuator. Seems both of our amps may be very picky regarding single ended preamps and ic's? Al has tried to help me figure out my issue, but I still have a buzz - slight buzz on both speakers. Sounds like some sort of ground loop issue to me.

Strange for sure..For me the buzz only came when I changed speakers from active to passive. No buzz with active speakers, buzz with passive.

System sounds great so I live with it. Can't hear it 10 feet back.

I tried adaptors like you with pins 1 and 3 tied, still a buzz. I purchased an ic that goes from RCA to xlr with 1 and 3 combined, still have a buzz.

I am getting some kind of ground loop issue when my ic's are connected. Any ic's. I may try your transformer answer, but now wonder if their will be an input impedance mismatch with my pre and the Jensen transformer? The Dude has 5k ohms of output impedance.
Mine preamp's chassis is indeed grounded to the middle pin of the iec. Again, the buzz comes when the preamp is off and unplugged even. I have an amp issue. I called Aesthetix today and they gave me some other things to measure on the amp.

I will report back on how this ends up so all can learn. Thanks to all for the help.
Vett93 , please help me understand what you did? I am not understanding your fix? Are you saying you simply used a cheater plug on the amp? If so, tried that also.Thanks

Mitch2, thanks much for the offer. I want to try what Vett93 is saying and I may take you up on your offer.

Al, you may be right or I may have a ground issue that is induced between gear thru the ic's .....don't know. I have another system I may place the amp into today to see what happens.
Vett93 thanks for your response. Well, when my cd player is totally removed from the system by unplugging both power cord and ic's I still get a hum/buzz though the speakers. The buzz is not present with the amp and speakers only. As soon as any preamp I have here goes into the amp by ic's ( not power cord into the wall) then the buzzing begins.

My Dude is grounded at the AC inlet plug. The power supply also looks grounded, but I am not certain about the signal ground being wired to the AC ground as you say? I will ask Paul.
I will try shorting all 4 xlr inputs. I will try a Blue Jean cable also. Last, I will try direct hook to my cd player. Thanks to all!
The Dude is not the issue at all. I have tried three preamps in the system and one of them was a passive. As soon as ANY of these 3 pre's are hooked up by ic's only - the buzz starts. Just an FYI. The preamps don't even have to be plugged into the wall.

My issue has nothing to do with the Dude. I seem to have a strange room or total system issue. The system was dead quiet with every other amp I have used with the same Dude as well as my last set of active ESL speakers. Please understand this is not a preamp issue. The Dude is properly ground and built to the highest standards and like a tank.

Thanks to all for the help thus far.
Well the amp seems to be the issue after more testing. I tried using Blue Jean cables that are well shielded, but the buzz continues. Again, with the preamp off and unplugged the buzz continues.

I measured as Ralph stated and could not get any reading on my ohm meter (too low) when testing for ground on the RCA 's and the middle (ground) on the AC inlet of the amp. My meter measured too low to read on the (m)ohm setting.

I tried shorting out all 4 xlr inputs between pin 1 & 3 and still have the buzz. This Buzz was not there when my previous Soundlab speakers were in the system. The buzz came for the first time when I replaced the Soundlabs with a passive speaker.

I am at a loss. I spoke with Aesthetex and they had no answers. I will try them again now, but they also seem stumped.
I meant to say I measured no ohms. I assume getting no ohms means there's no connection from the signal ground as measured at the RCA socket to chassis. Same with the power cable ground to chassis. The chassis has no resistive connection and seems isolated from everything.

This does not seem good to me.
I measured the Atlas amp again. It turns out if I touch the back steel plate I get no ohm reading. However when I touch a screw on the back plate with the center power cord ground pin on the iec I get a 14 ohm reading.

I learned this from calling Aesthetix. They tell me the amp is fine and I have some sort of unique room/house situation. Seems they will not be able to help me anymore and suggested I try a balanced preamp. Well, my amp has RCA inputs for a reason and I need to use them!

I am starting to doubt I will ever get an answer.

Vett93, the speakers buzz with my cd player unplugged and ic's also taken out that go to the cd player. So the source it not at all in play here.

I need to bring the amp to another home and system and see what happens.
My CD player is grounded to the chassis by the power cord middle pin. I did hook it up directly to the amp and still get a buzz out of both speakers. I will try the amp in another system tonight to see what happens.
Maybe a power conditioner?
Correct, passive speaker. I ha!ve been working with Vett93 and he has stepped me through all kinds of tests. Thank you for being so patient with me! Through it all I still have the same buzz out of both speakers. The buzz is not present under three conditions we have tested.

1) the Atlas amp turned on and connected to the speakers with nothing else hooked to the amp

2) the Atlas amp hooked to an ic feeding into an RCA socket with the two leads connected and shorted

3) as above with a 1kohm resistor between the RCA ground and center pin.

The buzz is present with any other condition. Here is a recap of what causes a buzz through the speakers.

-Three different single ended preamps turned on or off hooked to the amp. They each caused the same buzz wether they were on or off with or without a source hooked up .

- hooked direct to two different cd players the buzz was the same - no preamp

- cheater plug on amp, then preamp, all xlr inputs on the amp shorted between pin 1 and 3 with purchased xlr connectors having pin 1 and 3 shorted

Vett93 can better explain all the RCA, iec, pin, chassis etc measurements we made concluding all was wired correctly with the amp's input.

Stumped is an understatement. I wonder if a conditioner of passive or active nature is needed to cure other issues?

Through all of this testing all 4 xlr inputs were shorted between pin 1 and 3.
I just read this in my Aesthetix Atlas's manual. " each channel is a balanced bridge amplifier, thus the negative speaker terminal is not a ground, and cannot be connected to a system ground or loudspeaker system with a common ground. Consult your speaker builder to confirm that your speaker does not have internal circuitry with a common ground."

Well, my speaker is passive - Nola Viper Reference. As for what this means above, I have no clue. I can't imagine a passive speaker would have this sort of grounding issue however?
Thanks Al. I just inserted two shorted RCA jacks on the unused crossover inputs on the amp. Still have the buzz however.

Wonder if my extra preamp inputs should be shorted?
I found a bunch of unused RCA cables and connected the ground and center wires to short the jacks. I places these on my 3 sets of unused preamp inputs. Still have the buzz. Still think this may be a good idea however.
Vett93 summed it up very well. My speaker and other cables really did not change position. My speaker cables are simply solid core copper runs and very straight forward. Changing power or ic cable brands did nothing to change the hum.

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?
Ok, did one additional measurement per the instruction Jognsonwu above.
I measured the ohms reading from the RCA center to each of the eight 6sn7 socket pin numbers.

I did this to check the input grid stop resistor.This grid dropper resistor is used to form a low-pass filter to get rid of RFI/EMI. For more reference, please see the following link:

Pin one should measure 1000 ohms, not 100 according to two individuals that are helping me. Love input from Atmasphere or Al or others who may know something on the this subject.
Here are the measurements,
1.   100 ohm
2.    3.9 mohm
3.    1.45 mohm
4.   .527 mohm
5.    3.9 mohm
6.    1.45 mohm
7.   .527 mohm
8.   .527 mohm
Checked and recheck.......before I call Aesthetix I could use some confirmation. I am not the most tech savy and must say I have a hard time thinking they would miss such an "obvious" thing? My amp is not under warranty and wonder if this is something that should be made right, or simply just one way to build an amp?

I greatly appreciate the help I have received from all and this is the last request I will make for help before calling Aesthetix again.
Jognsonwu, thanks for your insight. I am not sure how to wire such a resistor as my amp has a circuit board for each input tube/channel. Hard, if not impossible , for me to wire in a 1k resistor. Wish the amp was point to point wired!

It may be possible for me to simply solder an additional 1k resistor from the RCA to pin one and not undo anything else. Is this what you are suggesting?
Correction the grid stop resistor should measure over 1000 ohms and often is a very high value.
Update. The use of a Jensen input transformer under the brand Iso Max completely removed the buzz to a dead silence. Simply place the input transformer between the amp and preamp. Single ended preamp into the Jensen Iso Max using my RCA ic's and out from the Jensen Iso Max into my amp using xlr connectors. So the Jensen receives RCA in and xlr out. I am now able to use my amp in it's fully balanced mode.

The xlr ic's going from the Jensen to the amp must be 2 feet or under to avoid any signal deterioration.

The down side is the cost of the unit plus the cost of an extra set of ic's. Not sure as yet if then Jensen changes the sound as I am using some pro sound Mogami xlr's for now. The sound does seem a little more polite or less alive, but this my be the new set of IC's?

I will soon receive a set of xlr ic's of the same brand that I use throughout my system. I will update all as to wether the Jensen input transformer changes the sound.

The sound is very good with the inexpensive Mogami cable however. A little less top end sparkle is what I notice thus far.

I also left Jensen a message to clarify the compatability of the unit with a higher output impedance preamp. The site suggests the preamp should be no higher then 2k ohms , but other threads I have read seem to suggest this may not be the whole story.
Thanks Al. I will check into the cable capacitance to be sure I am doing all I can for best sound.
Atmasphere, I have not tried to run the Jensen with rca's as yet. I am so thrilled with the sound right now. Seems my amp really sounds best through the xlr inputs. All I know is my system has never sounded better plus is now very quiet.