Pre-amp output levels vs. hiss

[Dingman]

In search of the lowest "hiss" levels, would it be correct to have the output switch (hi\lo) on my Marantz 3300 on low? I haven't tried it on high, probably don't need to.

What specification best indicates level of hiss?

Basically, when I'm listening at higher volume levels and a quiet passage comes up, I can hear background hiss. It's almost unnoticeable on some tracks, while others are quite bad.

Do I also need to consider upgrading from standard CD's? I have read up alot of the threads here about quality changes from CD to SACD and it seems to be a crapshoot unless you really know what you're doing and stick with known good recordings.

TIA.

Edit: Marantz 3300 into Marantz MA-500's to KLF20's with Ti tweets.

[Guest " "]

What specification best indicates level of hiss?

signal to noise ratio is he spec. for home gear, 90db or better is good. lots of gear are in the 96db area. a few are in the 106db area. when you get down to below 85db's, you can sometimes hear stuff. also tweeter designs them selves can cause hiss....it was a popular say to say you have a snake in your tweeters.

[russ69]

What specification best indicates level of hiss?

Here's some info from Upscale Audio:

You can add an amp with less power and have the idle noise go up. Why?

This type of noise can be caused by a few different factors. One is the amount of gain in the preamp. Look at the specs. For instance, the PrimaLuna ProLogue Three has only 11.5dB of gain. Other preamps like the Audible Illusions Modulus 3A can have up to 30dB of gain... some have even more.

So when does this come into play? When you pick your power amp, the specification we look at there is input sensitivity. Some amps require only 0.8 volts to bring them to their full power. Others may require 2, 3, or even 4 volts to reach full volume. So the 0.8 volt model is more sensitive and takes less to get it going. Depending on the gain in your preamp this could mean less movement on the volume knob.

When could this be a problem? Usually if you are in a teeny room and sit close to the speaker, or if you have high sensitivity speakers. Using the same amp and preamp, and the volume set to the same spot, an 89dB efficient speaker will require more gain than a speaker rated at 101dB. And with the volume all the way down, the 101dB speaker will typically have more idle hiss. The dealer you buy your gear from should keep you on the sunny side of the street.

So you hear hiss when you put your ear up to the tweeter? Then dont do that! The best way to tell the salesman "I don't know anything" is by putting your ear to a tweeter in a store and then complain that the gear is noisy. If you hear a noise, how loud is the volume? The important thing is that the music signal far overrides the noise. So relax.

All equipment makes some noise. Buy your gear from a dealer that will make sure nothing is wrong, but that dealer better have understanding of the questions. I know of one dealer who told a customer the noise was because of an impedance mismatch between the preamp and amp. And that they were supposed to be equal. Say whaaaaaaaat? Tell him to go back and go to school. In fact spank him for me.

Remember...

#1: Noise has nothing to do with impedance.

#2: The impedance between components is a separate topic, and they are not supposed to "match". Well cover that as another topic.

Please note: Idle hiss is a question of gain and sensitivity. Not one of power. Think of it like a sports car. Gain and sensitivity is how touchy the gas pedal is on the car, power is how much horsepower the car has.

If one of the components is tubed, you can see if the tube is bad and perhaps make it quieter. But a noisy tube sounds very different from idle hiss, and you typically won't get a noisy tube in both channels at the same time.

Another thing you can try if your preamp has a ton of gain, or your amp has a very low input sensitivity is a small in-line device that attenuates the input to your power amp. They can be very helpful. Heres a link to a good one:

http://www.rothwellaudioproducts.co.uk/html/attenuators.html

[Dingman]

Whew, Ok. I think I understand some of that.

My amps:
Input sensitivity/impedance 1 V/30 kohm
S/N ratio 116 dB

The preamp has:
Hum and Noise < 1 uV @ rated output
Channel Separation > 40 dB
Frequency Response +/-0.25 dB, 6 Hz to 80 KHz
Rated Output Level 3 v RMS

Speakers are:
SENSITIVITY:
100dB @ 1watt/1meter

I can't find info on what changes that "output High\Low" switch does. I assumed I'd leave it at low, but I guess I'll just have to try it!

[LarryC]

I believe Marantz put in that switch in the 1960's for lower hiss on high-efficiency speakers, such as, um, K-horns. This is a gain-matching thing; the Hi position had higher preamp gain from in front of the volume control, and that noise would be carried on by the line stage and carried on through the amplifier and speaker. Hence the lo position for (for example) horn speakers.

[garyrc]

• I see your speakers are quite efficient. A little hiss, and a little hum, is the price we pay -- and it's worth it.

  The best speakers I've heard have always passed through at least a

  little hiss. They were Klipsch and JBL, ranging in efficiency from

  about 3 or 4 dB less efficient than yours to about 4 dB more efficient.

  Speakers don't create hiss, but they sure can pass it through!

• Until recently, I had a preamp/processor that passed through a

  little hiss and a quite noticeable amount of hum (noticeable by me, not noticeable by my family

  -- that's a problem -- with audiophiles!). Both

  originated after the volume control, so turning it down did not

  help. The power amps were absolutely noise free (from listening

  position) with the preamp/processor turned off. The problem had me running around unplugging the

  refrigerator, getting our power main inspected, looking for hum loops,

  and going crazy. That's another problem -- with audiophiles. Finally I

  solved the problem by turning down the input level control on my power

  amps by about 5 dB, blocking the hiss/hum at idle coming from the preamp

  ... BUT see below.

• There was a widely held belief in the '70s that turning down a power amp's input level control reduced resolution. I do believe I heard that with my old McInotosh MC40s. With my present amps, I tried comparing the "fixed input" (no level control at all -- full sensitivity) to the "variable

  input" at about 5 dB attenuation specifically for any differences in

  resolution. I heard a decline -- no I didn't -- yes I did.

  Audiophiles!

[LarryC]

Until recently, I had a preamp/processor that passed through a little hiss and a quite noticeable amount of hum (noticeable by me, not noticeable by my family -- that's a problem -- with audiophiles!). Both originated after the volume control, so turning it down did not help... Finally I solved the problem by turning down the input level control on my power amps by about 5 dB, blocking the hiss/hum at idle coming from the preamp ...

You are right, and I was wrong earlier, about the switch controlling gain from before the volume control. The switch controls the gain from the entire preamp, which therefore controls the gain coming from after, as well as before, the volume control. The noise you hear is from circuitry following the volume control, so in effect you are turning that down.

I believe that's the same as turning down the power amp gain.

I would leave your switch in the "low" position, if it sounds OK to you. I don't recall that much degredation from the Marantz gain switch.

[Dingman]

Thanks guys ('specially Gary and Larry), that's the sort of info I was looking for. Now, for sure, I do understand more about what that switch does.

Yes, the KLF-20's are effiecient and the Ti tweets didn't help at all either.

I do not have a gain control on the Marantz MA-500 power amps, so I'm SOL on that option.

I do have a few different pieces of equip (not very much by your guys'''' standards), so I'll play with it and swap things around to see if I can isolate and then minimize the hiss.

Thanks again.

EDIT: I need to check again, but I'm pretty sure the hiss volume gets louder as the pre-volume is turned up. I'll start there, by disconnecting first the pre, then the wires and see if I can eliminate the amp.

[mark1101]

Lots of good info here. Hiss at idle has always been a big pet peave of mine. With Klipsch horn speakers they are just magnifiying every little anomaly, so you really need to have a clean system to be void or close to void of hiss. There is also a point where you have to reasonably say..........this is normal. You can have a very quiet system, but in some situations a little hiss is the best you can do with a very sensitive speaker. You may never get it all out, and it could stil be a clean system........and nothing wrong.

Obviously, equipment synergy and the correct matching is what you want. But we can't always find perfect matches as we change our systems.

I know you already mentioned you can't do this right now with your amps........but what I have done is transitioned gradually to only amps with gain controls. This has been a huge help because you can better control the system gain structure. Again, in my case it was always the amps at full gain causing most of the noise as I always had pretty clean preamps. I don't have that issue now as all my amps have gain controls.

[LarryC]

I do not have a gain control on the Marantz MA-500 power amps, so I'm SOL on that option.

I do have a few different pieces of equip (not very much by your guys'''' standards), so I'll play with it and swap things around to see if I can isolate and then minimize the hiss.

Thanks again.

EDIT: I need to check again, but I'm pretty sure the hiss volume gets louder as the pre-volume is turned up. I'll start there, by disconnecting first the pre, then the wires and see if I can eliminate the amp.

With what you've described, your best bet is to leave the hi-lo gain switch on the back of your pre in the "low" position. The bane of people's problems with this has been high-power high-gain amplifiers, which are generally made with inefficient speakers in mind. A typical example is a sensitivity of only 0.5 v. to produce full power out!

I have had only low-gain amps in my system for years. In the case of my current OTL's, fortunately the manufacturer could take out one stage of gain, and he estimates that their sensitivity is now 2 or 2.5 v. in for 100 watts out, a far lower level of gain. They are exceptionally quiet except for a low level of OTL buzz and hum. The VRD's, with around 1.5 v in for full out (40 watts?) are very quiet.

Integrated amplifiers can somehow achieve almost nonexistent noise levels! Vintage Scott 299's are a good example, and they sound very good on Klipsch. One forum member has a new VAC integrated tube amp, the 1060 I think, which he says is dead quiet. That and tubes, too!

[Greg Oshiro]

<snip>I do not have a gain control on the Marantz MA-500 power amps, so I'm SOL on that option.<snip>

Maybe not quite so SOL. There are some fixed attenuators that can be installed in-line with the RCA cables going into the power amp. I found some at:

http://www.parts-express.com/wizards/searchResults.cfm?FTR=RCA+attenuator&search_type=main&WebPage_ID=3&searchFilter=RCA+attenuator

Caution: I have not tried any of these myself, so I do not speak (type?) from experience. I have no affiliation with Parts Express.

[Dingman]

Hmm, I'll check those attenuators out. Thanks for the tip.

[Dingman]

Update. Well, I'm still fussing with all of this. I'm not really asking more questions at this point since I think I have more research & testing to do, but maybe if I comment on what I'm hearing, someone will have a comment or suggestion.

So, in an attempt to get an idea of what to strive for in SQ (sonic quality, is that what you call it?), I stopped in at a local, highly regarded, been around forever (with the same sales and tech guys) where I bought my Marantz SR-4023. Told the guy there to let me listen to some full range speakers with a cost of under a grand on his SR-4023. He hooked up some Monitor RX6's that retail for around $750. The sound from those Monitors was really, really great. Hard to compare, I know, but the "quality" I perceived was far beyond what I'm getting at home with my KLF-20's. They seems so clear, with great highs, mids and bass. Imaging like I never hear at home either. No hiss at louder volumes. I think they were about 90 db sensitivity as opposed to the 101 db on the KLF's.

http://www.monitoraudio.co.uk/products/silver-rx/rx6/

Nope, I'm not making a direct comparison and I'm now trying to determine if it's really the KLF's or if my source is somehow inferior. At the store "Audio Labs", the source was a nice Marantz SACD of some sort. Maybe that's the crux of the biscuit, as FZ would say.

So, I'm fooling with a couple of different sources (although I don't have a SACD or a working TT right now), ...and will try other things as I think of them. I really wish my KLF's were small enough to just take to Audio Labs and try them there, on their system... but they are too damn big for me to move easily.

I also may have to look more closely at the KLF-20's, as Moray once asked me and I didn't really do it.

[garyrc]

I think they were about 90 db sensitivity as opposed to the 101 db on the KLF's.

That could do it. Everything else being equal, any hiss originating after the volume control would be 11 dB louder with a 101 dB sensitivity speaker, providing there are no attenuators or pots that are also past the volume control.

I recently replaced a good NAD pre/pro with a Marantz. The NAD both hissed and hummed through my Klipschorns (rated sensitivity between about 100 and 105 dB, depending on how you do it), but was just about totally silent through any of the other 3 stereo speaker systems in the house. The new Marantz has no hum and no hiss that anyone of us can hear coming through the K-horns. The difference? The NAD had noise created after the volume control.