Pre Amp? yes or not needed?

Should I add a Pre Amp to my ST-120? I only play CDs with my Oppo UDP205

Do you have enough output from the Oppo to get enough volume out of the ST-120? My setup won't drive my ST-120 to distortion, but will drive my wife to tell me to turn it down. Since I don't need more gain, I drive my ST-120 from a switch box fed by a DAC and a CD player. Building a Preamp appeals to me, but I can't justify the cost since I don't need the gain and everything sounds great.

Hops wrote:Do you have enough output from the Oppo to get enough volume out of the ST-120?    My setup won't drive my ST-120 to distortion, but will drive my wife to tell me to turn it down.   Since I don't need more gain,  I drive my ST-120 from a switch box fed by a DAC and a CD player.    Building a Preamp appeals to me,  but I can't justify the cost since I don't need the gain and everything sounds great.

I have plenty of volume, I just heard that the Pre amp can clean up the sound a little.

music wrote:

Hops wrote:Do you have enough output from the Oppo to get enough volume out of the ST-120?    My setup won't drive my ST-120 to distortion, but will drive my wife to tell me to turn it down.   Since I don't need more gain,  I drive my ST-120 from a switch box fed by a DAC and a CD player.    Building a Preamp appeals to me,  but I can't justify the cost since I don't need the gain and everything sounds great.

I have plenty of volume, I just heard that the Pre amp can clean up the sound a little.

No amp, pre or power, can "clean up" sound. If it's distorted it's final.
A pre can however adjust levels, it can have tonecontrols to adjust some recordings,
it can be a buffer to drive tape-recorder or computer soundcard, and it contains
input switching capabilities. It may also contain remote control for your convenience.
In addition a pre might allow a better placement of power amps(close to speakers or
away from pets and children) and still allow controls to be close to listener.
A quality pre will not distort the sound, a bad might. No pre means no added distortion.

Take your pick!

peterh wrote:

music wrote:

Hops wrote:Do you have enough output from the Oppo to get enough volume out of the ST-120?    My setup won't drive my ST-120 to distortion, but will drive my wife to tell me to turn it down.   Since I don't need more gain,  I drive my ST-120 from a switch box fed by a DAC and a CD player.    Building a Preamp appeals to me,  but I can't justify the cost since I don't need the gain and everything sounds great.

I have plenty of volume, I just heard that the Pre amp can clean up the sound a little.

No amp, pre or power, can "clean up" sound. If it's distorted it's final.
A pre can however adjust levels, it can have tonecontrols to adjust some recordings,
it can be a buffer to drive tape-recorder or computer soundcard, and it contains
input switching capabilities. It may also contain remote control for your convenience.
In addition a pre might allow a better placement of power amps(close to speakers or
away from pets and children) and still allow controls to be close to listener.
A quality pre will not distort the sound, a bad might. No pre means no added distortion.

Take your pick!

Thanks, its not necessary then.

music wrote:Should I add a Pre Amp to my ST-120? I only play CDs with my Oppo UDP205

In my vinyl only system for quite some time I used a PH-16 phono directly to a volume control then directly into my ST-70.  It sounded very good but I still wondered if a line preamp might be needed.  So just a few weeks ago I built an SP-12 line preamp.  The sound is significantly better with the SP-12-- more dynamic, wider more stable sound stage and imaging.  I also had periodic instances of channel imbalance when using just the phono preamp (sometimes I thought the RCAs weren't making a good connection so I'd be jiggling and swapping cables...).  With SP-12 in place that problem disappeared.

The output of the phono preamp should be ~2 volts, but I think there still needs to be a buffer to get sufficient drive to the power amp.

This may not really apply with your CD player...not sure.

Dave

I run a older oppo as a pre it has both Gain control with remote and a crossover for a sub if needed.
Also before the ultra player it had very good music streaming.

music wrote:

Hops wrote:Do you have enough output from the Oppo to get enough volume out of the ST-120?    My setup won't drive my ST-120 to distortion, but will drive my wife to tell me to turn it down.   Since I don't need more gain,  I drive my ST-120 from a switch box fed by a DAC and a CD player.    Building a Preamp appeals to me,  but I can't justify the cost since I don't need the gain and everything sounds great.

I have plenty of volume, I just heard that the Pre amp can clean up the sound a little.

Adding any device to the signal path can only degrade the signal to noise ratio, it can never improve it. Technically speaking, the degree of degradation is called the Noise Factor (NF), and it will always be positive, even for a billion dollar preamp, so it will always degrade the SNR. See Noise factor here:

https://en.wikipedia.org/wiki/Noise_figure

However, even though the preamp makes the signal a little less pure, you may still find you like the sound better because it has the characteristic sound imparted by the preamp's circuit. A little color from your favorite tubes can be very musical and there's nothing wrong about that. I use a line preamp because I just plain like it, and it also provides input selection, volume and balance controls.

It always amazes me when people say an ideal preamp should be as transparent as possible, and still claim they need one for optimal sound quality.

Now if there is an impedance mismatch between source and power amp, or the source has insufficient output level, things are different. In this case a preamp can make a huge difference because it is fixing a problem, but this is not likely to be the case with a CD player. A phono signal falls into this category and is essential.

So no, you don't need one, but it still might be fun to try.

FWIW

My only two sources, a DAC and scratch-built tube phono section, have plenty to drive my amp (ST-70.)  I'm using a Schiit passive pre- upstream of my ST-70 for basic volume attenuation.   It's just a volume pot and has switch between two sources. I bought it because it was simple and affordable, and it sounds fine by my ears.  

https://www.schiit.com/products/sys?gclid=CjwKCAiAlajvBRB_EiwA4vAqiLr6FH818H1sd3wmUvvleek0AqiFeEwrM-xq6cSbZYuNZEFqKsQiiBoClLAQAvD_BwE

There's passive pre-amps with a premium pot or stepped attenuator, but of course they cost more $$$.  I might scratch build one with better components one of these days, just so I feel better about it - but I'm in no hurry.

Technical considerations aside - an age old argument- a high quality preamp like Roy's SP14 will improve the dynamics of your system - more "drive".

Borrow one and see what happens. Let your ears decide.

SP14..way to go..but agree with let your ears do the talking.
Test drive the SP14 if you can.
$$ are justified for what you will attain in your system. MORE DETAIL.

http://www.firstwatt.com/b1.html

I've built a B1, but did not like it with my ST-70 and preferred my VTA SP14. However, the B1 is fantastic with my Firstwatt F5.

Michael

If you are having any issues with sound quality coming from those two components, I'd be shocked. The Oppo is rated as one of the highest quality D to A conversions available at this time. And the ST-120 is a legend of tube sound. That being said...

Tubes are colored. They provide a color that interacts with speakers and rooms to sound more life-like, unlike "transparent" amps and preamps that stop being transparent as soon as the sound leaves the speakers and bounces around the room. And since "transparent" amps and preamps aren't tuned to interact with their surroundings, they end up sounding harsh and flat. "Transparent" components look amazing on a scope and would sound great in a room with no reflections.

I say this as a preface to my statement that a preamp CAN improve sound quality (and by preamp, we all know we mean a tube preamp). It won't look better on a scope but it can give you more, as audiobill said, dynamics. It can give you more of that tube quality that interacts with rooms, make highs more clear and ringing and bass more enveloping, more fullness, less boom.

I bought a 200$ Chinese-made tube preamp based on the Marantz 7 gain stage, upgraded the capacitors and tubes, and was rewarded with a staggering improvement in dynamics, imaging, and soundstage, and not even the smallest perceived loss in sound quality. (my amp is a Dynaco St-70 II)

DAC's and other source components should be flat and transparent, they are feeding signal. Preamps amps and speakers are making music and placing it in the room to interact with the living and should be tuned as such.

MechEngVic wrote:

... It can give you more of that tube quality that interacts with rooms, make highs more clear and ringing and bass more enveloping, more fullness, less boom.

I agree that a preamp can improve the listening experience by coloring the sound, I just argue against those who claim adding a preamp can somehow *preserve* the sound, that is, make the output a more faithful copy of the input. This is impossible.

It changes the sound in a way that is pleasant. Nothing wrong with that.

My personal SP14 experience . . .

For the ones I’ve built, I measure less than 1.8 mv AC at the outputs, typically, very quiet.

And the SQ compares favorably to my $10k Conrad Johnson et5.

Maybe recheck your handiwork in accordance with my earlier posts on grounding procedures?

Best,