« previous next »
Pages: [1]   Go Down

Author Topic: Rogue preamp/Emotiva amp mismatch?  (Read 8091 times)

bmwr75

  • Guest
Rogue preamp/Emotiva amp mismatch?
« on: December 30, 2010, 09:52:42 AM »
Hooked up a Rogue 66 tube preamp (output impedance = 650 Ohms) to an Emotiva XPA-2 solid state amp (input impedance = 23.5k ohms) today. Have a very noticeable hum coming thru the 100 db efficient Klipsch speakers. When I switch the preamp off, the hum goes away.

Do I have a gain or impedance mismatch causing the hum?

The preamp was previously connected to a Dynaco ST70 in the same location and the hum was not noticeable.
Logged

bmwr75

  • Guest
Re: Rogue preamp/Emotiva amp mismatch?
« Reply #1 on: December 30, 2010, 02:22:55 PM »
Nevermind.  I found this thread on impedance matching.  Seems my noise problem lies elsewhere.

http://www.audiokarma.org/forums/showthread.php?t=289288
Logged

Offline schwarcw

  • Ready For Intervention!
  • ******
  • Posts: 1625
  • Karma: +0/-0
  • No one here gets out alive!
Re: Rogue preamp/Emotiva amp mismatch?
« Reply #2 on: December 30, 2010, 11:36:47 PM »
Hmmmmm!  I wonder what's up with that???  The preamp sounded fine yesterday.  Have you put the Emotiva in another setup to see if the hum is in the amp?
Logged
Carl

Offline F1nut

  • Ball Buster
  • *****
  • Posts: 544
  • Karma: +0/-0
Re: Rogue preamp/Emotiva amp mismatch?
« Reply #3 on: December 30, 2010, 11:39:43 PM »
I think your Rogue is trying to tell you something. The question is, are you listening?
Logged
  'Political Correctness'.........defined

"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a turd by the clean end."
 

bmwr75

  • Guest
Re: Rogue preamp/Emotiva amp mismatch?
« Reply #4 on: January 01, 2011, 10:19:52 AM »
Quote from: F1nut on December 30, 2010, 11:39:43 PM
I think your Rogue is trying to tell you something. The question is, are you listening?

F1 nut,

Enlighten me.  What do you think might be going on?

Scott
Logged

Offline Zoot Horn

  • Double Secret Probation!
  • **
  • Posts: 233
  • Karma: +0/-0
Re: Rogue preamp/Emotiva amp mismatch?
« Reply #5 on: January 01, 2011, 10:45:05 AM »
jumping in kinda late,, but have you tried another amp in the mix?
Logged

bmwr75

  • Guest
Re: Rogue preamp/Emotiva amp mismatch?
« Reply #6 on: January 01, 2011, 12:12:32 PM »
Today I tried a different preamp in this system, a vintage Marantz 3200, and the noise went away.

Reconnected the Rogue 66 preamp today to the Emotiva amp.  Lifted the ground on the preamp, no change in the noise.  Lifted the ground on the amp, no change in noise.  

FYI, this doesn't sound like a 60 Hz hum to me.  It is a much higher frequency.  In fact, it is coming from the midrange or tweeter horns (not the woofers) on these Klipsch KLF-20 speakers, which are 100 dB efficient.

When I hit the Mute button on the preamp, the system goes dead quiet.  Another weird thing.....with no signal to the preamp, I can turn the volume knob to maximum and the noise attenuates as the knob is rotated and nearly disappears when the volume knob is at maximum.

So, my conclusion is the problem is in the preamp, or there is just a great lack of synergy between the Rogue 66 pre and the Emotiva XPA-2 amp when driving very efficient speakers.  Way too high a noise floor.......
« Last Edit: January 01, 2011, 12:14:47 PM by bmwr75 »
Logged

Offline F1nut

  • Ball Buster
  • *****
  • Posts: 544
  • Karma: +0/-0
Re: Rogue preamp/Emotiva amp mismatch?
« Reply #7 on: January 01, 2011, 06:29:31 PM »
Quote from: bmwr75 on January 01, 2011, 10:19:52 AM
   
F1 nut,

Enlighten me.  What do you think might be going on?

Scott

I think it's time to change the tubes.

On another note...Emo, really?
Logged
  'Political Correctness'.........defined

"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a turd by the clean end."
 

bmwr75

  • Guest
Re: Rogue preamp/Emotiva amp mismatch?
« Reply #8 on: January 01, 2011, 06:34:05 PM »
Quote from: F1nut on January 01, 2011, 06:29:31 PM
Quote from: bmwr75 on January 01, 2011, 10:19:52 AM
   
F1 nut,

Enlighten me.  What do you think might be going on?

Scott

I think it's time to change the tubes.

On another note...Emo, really?


Did change the tubes.....had no effect.

What is your first hand experience with Emotiva amps?
Logged

Offline F1nut

  • Ball Buster
  • *****
  • Posts: 544
  • Karma: +0/-0
Re: Rogue preamp/Emotiva amp mismatch?
« Reply #9 on: January 02, 2011, 02:47:29 AM »
Ah so, I must have missed that. Hmmmmm......in that case it would seem you have two pieces that don't like each other. It happens. A few years back I bought a very nice tube pre amp that didn't like one of my CDP's or vice versa...anyway, the CDP wasn't going anywhere, so the pre amp made a hasty exit.

I have friends with first hand experience, who's ears I trust enough to know all I need to know about those products.
Logged
  'Political Correctness'.........defined

"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a turd by the clean end."
 

Offline Falcon

  • Polk Killer
  • ****
  • Posts: 1131
  • Karma: +0/-0
Re: Rogue preamp/Emotiva amp mismatch?
« Reply #10 on: January 02, 2011, 08:18:52 PM »
Hey Scott, if the Emo is not working out for you,  give me a call..
Logged

Offline thuffman03

  • Zen Master
  • *****
  • Posts: 1097
  • Karma: +0/-0
  • CarverFest Evictee
Re: Rogue preamp/Emotiva amp mismatch?
« Reply #11 on: January 06, 2011, 02:33:41 PM »
The Rogue and the Emotiva must have a "Error Type 101: Mismatch Error"
Logged
Got Carver?
Pages: [1]   Go Up
« previous next »