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

Showing 7 responses by atmasphere

atmasphere's avatar
atmasphere
11,575 posts
 
This is not a power amplifier issue!

This is a noise problem in the preamp. Ahendler got it right.
atmasphere's avatar
atmasphere
11,575 posts
 
Al, when you turn up the volume and that results in noise, that is a preamplifier problem. Its true that the amp might have a certain low sensitivity requiring a higher volume setting, but even if the amp was more sensitive, you would still get the same noise even though you didn't turn up the volume as far on the preamp.


atmasphere's avatar
atmasphere
11,575 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.
atmasphere's avatar
atmasphere
11,575 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?
The line stage gain will not make any difference. The volume control won't affect the noise of the line section. The only thing it can affect is how much noise is present from sources, like the phono section. Its my opinion that this is where the problem lies. It might simply be noisy tubes and it could also be that the phono cartridge has output slightly too low for the phono section to work with gracefully.


atmasphere's avatar
atmasphere
11,575 posts
 
^^ bigger amps won't cure this problem as it is not caused by amplifier power or the lack thereof.

I have seen problems with cartridges where the magnet structure was damaged and has caused low output in both channels. The Whest, while not my favorite phono section, is not known for noise, so right now I am suspicious that the cartridge might have taken a hit somehow and is not making the proper output voltage- hence the noise.

I would try a different cartridge to test this theory.
atmasphere's avatar
atmasphere
11,575 posts
 
So, does this experiment show that the preamp is quiet and the phono stage is noisy?  Or, is it still the preamp somehow, and the higher gain of the phono stage is bringing out the inherent noise in the preamp somehow?
That's what I was saying earlier...

BTW a bit of hum on the DCP input is likely coming from the CDP itself.
atmasphere's avatar
atmasphere
11,575 posts
 
No power issues in this case.
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