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I have this K&M (Korn&Macway) SP100 preamplifier wich has HUGE gain, more than any other preamp I own (SAE Mk 1B, Sony TA-E86B). it used to be a real problem when used with my Technics SE-a5 power amp; it seems to be less of a problem with my 18watt/channel class A Sony TA-N86B.The combination actually gives glorious sound, much better than with the Sony preamp.
But my speakers are 104dB, all horn loaded, and with the preamp's high gain I really don't have enough control over the volume. The stepped volume control already is "loud" on the first step, and starts shaking the room once you pass the 9 o'clock position.
Setting the output level of my Kenwood DP7090 CD player to -10dB does the trick and seems to provide a more natural sound (i suspect because the inputs of the preamp are very sensitive, but I don't have any number, that preamp being very rare)
my question being: is it ok to just set the output level of the CD player to -10dB? what kind of volume control is it? digital? analog? any chance by doing so i'm actually lowering the resolution? would I be better with inline attenuators?
thanks
Edits: 09/16/14Follow Ups:
Try Harrison labs inline attenuators at the input of your power amp.
This should also keep the noise floor of the system well under control.
-PB
As long as you're happy with the sound, that's good.Beyond that, if you simply "want to know", with the emphasis on "know" rather than "guess or wonder", then the first thing you need to do is to know the input characteristics and gain information of your preamp.
Since you don't have a manual which cites that info, you need to find a competent tech who can measure it properly. This is a REQUIREMENT before you can go any further.
AFTER THAT, you can begin to think about how the output of the CD player mates with the input of the preamp. You DO have the player output info, correct?
You also need to know the input sensitivity for the power amp.
With regard to adding an in-line attenuator, there already is one in your CD player. I seriously doubt that it's a gain control. So, before you go buy attenuator stuff, use the one you already have.
Although the manual says to not use "too much" attenuation, that's a relative term. "Too much" could mean that the signal level becomes too low, resulting in noticeably increased noise. Since it has a range of 0-70dB, a 10 dB attenuation would hardly seem to be "too much".
This brings us to the issue of noise floor versus distortion due to overload.
Some types of distortion can be pleasing up to a point, because it enhances the sense of loudness. However, once the sense of increased loudness becomes overcome by the sense of degraded sound quality due to distortion, then we've reached that output level limitation.
Similarly, some electronic noise can be acceptable - until it begins to intrude upon our listening to the "purity" of the desired sound.
This range between offensive/noticeable noise and offensive/noticeable signal distortion largely defines the upper and lower limits of acceptable output level.
In short, the first thing you have to do is to KNOW your preamp characteristics. Get that nailed down. Then, you can begin the path to adjusting output and input levels properly. Until then, you're guessing.
:)
Edits: 09/16/14
Thanks for all the input.
As I said, I'm happy with the sound. I have no noise, huge dynamics, purity, really nothing to complain about.
I was first attenuating only by 5dB, and on some music, I could hear something was not quite right. For example, on classical music, voices sounded a bit "honky" and metallic. Like a bad horn speaker. My speakers are horns, but they DON'T "honk". Reducing by another 5dB made the sound much more natural and all honkyness is gone. Image depth has also improved.
I don't need to know what the ideal attenuation should be as long as it sounds good; I was more concerned about the fact that the output level control of the CD player is remote controlled, and I was worried that the level attenuation would somehow happen in the digital domain, and maybe reduce the ultimate resolution of the signal? I really don't know much in digital theory, and I have no idea how this attenuation works...
But it sounds very good to my ears so far. So maybe I should just stop worrying about the theory...
You're very welcome. Just to be clear, I don't design circuits, I just use them. :)
But the output/input/gain stage management issue is very real, not theory.
It's one of the things which professional audio recording and reproduction engineers are always cognizant of. We want to have each component working in it's optimal range and not introduce excess noise nor distortion into the signal.
With that in mind, don't be surprised if reducing the CD output another 10dB actually improves the sound. But, this will mean another 10dB of noise for equal output level. Maybe it matters, maybe it doesn't. You're the judge.
:)
Use the stepped attenuator as an inline attenuator for the CDP. They are very transparent and will work very well in that position. A typical volume control to attenuate an inline source will have rolloff and loss of dynamic problems. Just been there too.
charles
""It is not favorable for the sound quality to decrease the output level from this unit too much. Use these keys for coordination with other line
levels.""
Ultimately it's up to your ears, I like the idea of a passive linestage too when an active preamp with gain is not needed like in your case. I use a passive myself.
ET
I remember reading that from the manual as well. I might still have it around somewhere. But they don't mention what "too much" might be; here, I decrease by 10dB and it seems to be fine... you can go all the way down to -70dB or more(?)... plus they don't say WHY. I guess i will use it like this for now, and maybe order some inline attenuators when i'm a bit less tight with cash.
OK that's it then, if you don't hear negative affects then good. Also now that I know it attenuates into the 70's, 10-20 should be fine. Digital volume controls become bad when they reduce a lot not so bad when reducing a little. I think you're fine.
ET
Given the high sensitivity of your speakers you could bypass an active preamp all together. IF CD listening is your only source, you could use a tube buffer stage that has a volume control, maybe something like a Decware ZBOX to add some body to your sound. Any passive preamp with a volume control would also work.
Thanks for your reply, but there are few reasons why i'd love to keep the preamp:
1) it's easily the best piece of audio gear i've ever possessed and plays a big part in the sound i'm getting and enjoy so much. I've had quite a few preamps dring all those years (NAD 1300, Rotel RC980BX, Technics SU-A6, Marantz SC80, DIY Kaneda, SAE Mk 1B fully restored, Sony TA-E86B...) and this is completely in another league. Makes the hair on the back of my neck rise!
2) I'm currently fixing a record player to enjoy vinyl replay as well
3) I've been playing with no preamp at all and passive preamps and if the result might be slightly more transparent it's only by a very small margin such is the quality of this preamp. But the punch, body, and speed it brings to the sound was very sorely missed.
all I need to know is if using the CD player output level control does any harm to the sound (not that I can hear any, but I wanna know). if not, then all is well. if it does, the i'll buy inline attenuators from goldenjack or similar. :)
"all I need to know is if using the CD player output level control does any harm to the sound (not that I can hear any"
Seems to me that you already know...
Maybe it's time to just enjoy!
Rick
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