2. amps-preamps
  3. 123296-8622

Will Changing my 100 Watt Tube Amp to a 200 Watt SS Amp Solve My Problem?

Hello All,  I have a 100 watt Audio Research VT100 mk II amp, with an Audio Research LS-25 preamp.  My speakers are relatively low in sensitivity, and I find that I must turn the volume up to 3 o'clock on the preamp to get enough volume for a loud listening experience.  When I do that, I am introducing more background noise.

I would like to achieve a quieter noise floor.  I am also curious about the limits of the 100 wpc amp with the Mira Monitors.  Would an older Krell 200 watt class A amp "control" the speakers better?  If so, what are the benefits of this?  There are a few amps on this site that caught my eye, all about the same value as my amp, so I can potentially make a move with very little cost.  Is this a good idea? How much wattage increase is necessary to get a significant enough difference?  Would a jump to 150 watt solid state be sufficient?


here are the 3 amps that caught my eye:

Ayre: https://www.audiogon.com/listings/solid-state-ayre-acoustics-v-5xe-amplifier-2016-02-05-amplifiers-h...

Krell: https://www.audiogon.com/listings/solid-state-krell-ksa-250-2016-02-14-amplifiers-91754-monterey-par...

BAT:
https://www.audiogon.com/listings/solid-state-balanced-audio-technology-bat-vk-250se-bat-pak-2channe...



You can see my complete system here if you want to know more about the other components:  https://systems.audiogon.com/systems/5421



Thanks!
Mark
marktomaras
atmasphere's avatar
atmasphere
11,615 posts
 
After tinkering with the placement of the phonostage and the gain settings, I am suspecting the preamp is the culprit.

Am I wrong in feeling funny about 3 o'clock on the volume to get a rockin' experience? Seems like the high dial position is pushing the ability of the preamp too far.  One would think that my pre and power amp should be a good match though. They are both from the same era, same company, and same price point.

as it is, the sound is excellent, I am just complaint about the noise floor, which could be reduced.
What Al said, plus it might be that you have some noisy tubes.
elevick
2,636 posts
 
Ok, 6 ohms isn't so bad.  However, 85db is pretty paltry.  Your AR should be able to drive almost anything sufficiently.  Although, if you do the match your max output will be about 104db-105db at 100 watts which is not close to THX or rock concert levels.  400 wpc will get you to the 110db range.  You need to borrow a pair of BIG monoblocks...

Question:  Have you had your tubes checked?  One leak/short/old tube could be adding to this if you are getting noise or harmonics when pushing it.

mattmiller's avatar
mattmiller
1,479 posts
 
MARK, I agree with elevick... 85db speakers are not going to work well with tube power amps! I dont care what brand. Get a SS amp with proper input to match your pre amp and I assure you, the issue will be gone.


Matt M

almarg's avatar
Ag insider logo xs@2x
almarg
9,670 posts
 
Get a SS amp with proper input to match your pre amp and I assure you, the issue will be gone.
Matt, sonics **might** be better, but the noise issue (which the OP has stated is the main concern) will not be gone. See the posts above by me and by Ralph/Atmasphere.

Also, before going to a more powerful amplifier it would be prudent to research how much power the particular speakers can handle without their sonics degrading, or worse. The only relevant spec I can readily find for the Rockport Mira Monitors is a minimum amplifier power recommendation of 50 watts.

Regards,
-- Al

jmcgrogan2's avatar
jmcgrogan2
6,346 posts
 
Mark, your ARC LS25 is a  selectable gain line stage. It looks like you can set the gain anywhere between 0 dB and 18 dB. What do you currently have the LS25 gain set at?

Cheers,
John
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