LaScala AL5 Noise

[Troll]

10 minutes ago, Coytee said:

Have you *actually* used a shorting plug on your inputs yet?

 

I read above and didn't ascertain that you actually did it.  perhaps you did....my wife says I'm too picky on the word someone uses and I don't read between the lines.

 

Anyway...  I had a similar issue and ended up with some amps that have variable gain so I could lower the gain and lower the noise.  When I discovered my issue, I had a dbx BX-1 which has a 1volt input sensitivity compared with (I forget) something like 2.25 with a McIntosh amp I also had.  Again, I forget the actual number but the dbx amp was a high strung amp!

 

Now, you can put your ear inside the tweeter and not hear any hiss BUT, I've got the gains turned to about 25% of their range.  I don't know what that infers the input sensitivity might now be.  I'm guessing you know this but, it's not your speakers.  It's the diet they're being fed.

Doesn’t that mean if you turn down the gain you’re effectively disabling all those watts you thought you paid for?

[OO1]

nope , it means you're using the amplifier with less noise ,  clean power , 0  distortion in the sound 

[Shakeydeal]

Just now, OO1 said:

nope , it means you're using the amplifier with less noise ,  clean power , 0  distortion in the sound 

Show me an amplifier with “0” distortion. 
 

I’ll wait…..

[OO1]

 sure can  ,   Sansui amps    0.003..or  0,005  or less  ,   do you need me to give you the model no 

[Coytee]

1 hour ago, Stephen Buck said:

Doesn’t that mean if you turn down the gain you’re effectively disabling all those watts you thought you paid for?

 

My understanding is it will ground everything and whatever is left, is the base noise level of the amp.  Just take (what I presume you might use) an old RCA wire.  Snip it in two.  Strip the leads on each half to short them together.  Put one into the Right/Left inputs and see (hear) what's left.

 

If you do this and hear the noise then as I understand, you'll never be able to get rid of it.  On the other hand, if it DOES "go away", then I'm not sure what your next step would be.  I'll leave that to those more learned than myself.

 

(could be just about anyone!)

 

 

[billybob]

Has watts so, turn the gain down if the hiss is a bother.

May not eliminate but can attenuate.

[Shakeydeal]

10 hours ago, OO1 said:

 sure can  ,   Sansui amps    0.003..or  0,005  or less  ,   do you need me to give you the model no 

Technically it’s still not zero. And I would venture a guess that they do measurements like most of the SS amps did, only at 1K. 
 

But the most important take away here is that ultra low distortion doesn’t = quiet. My last three tube amps were so quiet that if you put your ear next to the speaker you’d swear they weren’t even turned on. And I guarantee you that none of them has “0 distortion”.

 

OP

 

The problem with noise in a system is when a perfect storm comes together. Take a high efficiency speaker, add a high gain preamp and amp, with a high output source , all it takes is a little noise to wreak havoc. This is why I don’t like having gain in the preamp stage if I have enough voltage gain in the front end of the amplifier. If you add a high gain preamp you only throw most of it away with attenuation.

[Troll]

Here’s the AI generated answer:

 

The noise floor of an amplifier is the additional increase in noise beyond the gain of the amplifier when the input of the amplifier is terminated¹. To establish the noise floor of a power amplifier, you must first short out the input of the amplifier by using a shorting plug². The amplifier’s power rating can impact the noise floor level³. Adding a pre-amplifier will boost signal levels above the noise floor, but across all frequencies⁴.

Learn more:

1. dsp.stackexchange.com2. diyaudio.com3. sweetwater.com4. signalhound.com

 

I saw somewhere someone saying that some amps trade a higher noise floor for lower THD.  Not sure if that is real.  But noise floor is different than THD ratings I think. 
 

“Noise is also typically distinguished from distortion”

https://en.m.wikipedia.org/wiki/Noise_(electronics)

Pass Labs refers to THD+N in their brochure where N is the noise floor.  But their product specs are sparse and incomplete. 

 

In the amp specs I have I think it might be represented by signal to noise ratio and residual noise shown here.  Also note the THD graphs showing the lowest distortion is achieved with 8ohm loads. 

Edited July 7, 2023 by Stephen Buck

[henry4841]

12 hours ago, Stephen Buck said:

Doesn’t that mean if you turn down the gain you’re effectively disabling all those watts you thought you paid for?

  Payed for more watts than needed for sure but in this original poster's case he already had the extremely high end Pass Labs amplifier before purchasing speakers. I expect anyone with good enough hearing can hear something with ear to speaker. I have amps and like Shakey and cannot hear a thing but that does not mean others might. Guy at Pass Labs gave the best answer to the question. I would not give it any thought myself if one cannot hear anything, or practically nothing, a few feet away. It only annoys me when you can hear noise on a quite passage from my listening position. It may well be the OP has excellent hearing and others may not hear a thing. 

 

An old mechanic gave me a good answer when I was complaining to him about a rear end noise on a car. After he heard it he just said turn the radio louder and it will go away. 

 

[Troll]

Interesting per https://www.passlabs.com/wp-content/uploads/2020/05/brochure-pass-labs-2020-website.pdf the number of output devices per channel on the X350.8 is 72.

 

”Output devices per channel refers to the number of transistors used by the amplifier manufacturer in the output stage of each channel. In theory, by using a great number of output devices, there is less stress on each one, which decreases the likelihood of failure. ”

 

However more components usually equals higher noise and distortion. 
 

For comparison the XA25 has 4 output devices, and the claim is “The result is faster, lower distortion, lower noise, higher damping and larger Class A operating envelope into low impedance loudspeakers all in a simple 3 stage circuit with total of three pair of push-pull gain transistors.”. The output is 25 watts per channel. 
 

 

[Troll]

24 minutes ago, henry4841 said:

  Payed for more watts than needed for sure but in this original poster's case he already had the extremely high end Pass Labs amplifier before purchasing speakers. I expect anyone with good enough hearing can hear something with ear to speaker. I have amps and like Shakey and cannot hear a thing but that does not mean others might. Guy at Pass Labs gave the best answer to the question. I would not give it any thought myself if one cannot hear anything, or practically nothing, a few feet away. It only annoys me when you can hear noise on a quite passage from my listening position. It may well be the OP has excellent hearing and others may not hear a thing. 

 

If OP has kids they will hear it.  My son noticed when I switched from old Sony STR-DE935 AVR to new Yamaha RX-A8A.  He can hear the noise floor of the Sony from the couch at 12’ on both my vintage Klipsch Chorus and the new AL5s, but he cannot hear the noise floor from either the Yamaha RX-A8A or the M-5000.  The room has 2 pair of Chorus and the AL5s so it’s very obvious is there is any noise from anything being surrounded by 6 high sensitivity horn tweeters.  Hiss used to bug me as a kid but honestly I hadn’t noticed the Sony noise.  Not sure if it increased with age or was always there. 

[Troll]

9 hours ago, billybob said:

Has watts so, turn the gain down if the hiss is a bother.

May not eliminate but can attenuate.

There is no gain knob on the X350.8.  Not like a Crown amp.  Also no gain control on Yamaha M-5000.  The M-5000 documentation just says when using dual mono/bridge mode “Since amplification will be doubled in this configuration, adjust the volume level appropriately on the connected preamplifier. If you are using a Yamaha preamplifier that features a GAIN selector, adjust the volume level using this selector so that you will be able to use volume controls on other components in the usual way.”

 

So the answer is basically to get a quieter amp which original poster has decided to do.  But OP could also stick existing amp in the garage for a nice winter heater, and use it for outdoor speakers or return to less sensitive speakers.  I just feel bad this was his path and the AL5s revealed/caused a problem for him.  As a new AL5 owner myself I get incredibly excited when I play them.  Friends get that surprised “voice in the room” reaction and have looked around for other people.  It’s what I call a “real speaker” when people think the sound is a person or instrument in the room.  My Chorus are especially good with piano realism, and the AL5s are especially good at voice, in my opinion of course. 

[henry4841]

32 minutes ago, Stephen Buck said:

If OP has kids they will hear it.  My son noticed when I switched from old Sony STR-DE935 AVR to new Yamaha RX-A8A.  He can hear the noise floor of the Sony from the couch at 12’ on both my vintage Klipsch Chorus and the new AL5s, but he cannot hear the noise floor from either the Yamaha RX-A8A or the M-5000.  The room has 2 pair of Chorus and the AL5s so it’s very obvious is there is any noise from anything being surrounded by 6 high sensitivity horn tweeters.  Hiss used to bug me as a kid but honestly I hadn’t noticed the Sony noise.  Not sure if it increased with age or was always there. 

I have a grandson that can hear a dog whistle. No one else in the family can. He cringes when he hears it. 

[Troll]

1 hour ago, henry4841 said:

I have a grandson that can hear a dog whistle. No one else in the family can. He cringes when he hears it. 

It’s possible that running the grandson out of the listening room is desirable, much like those insect and rodent ultrasonic repellents purport to do.

[henry4841]

Remarkable high frequency hearing. 

[sixspeed]

The low watt Class A Pass amps seem to work best for Heritage of all Pass' designs. New McIntosh is very quiet as well. Something like a MC-152 if you want to stick Class AB would be a nice choice. The MA5200 I had, non-autoformer was very quiet and sounded wonderful, it's essentially the integrated version of the 152. A MC-152 or Bryston 2.5B3 would be on my personal shortlist if I were you. Both are direct competitors and priced the same in the $4800-5500 price point. Bryston has a 20 year warranty guarantee on all their analog gear. Yamaha I agree makes some very nice amps but most are integrated amps and their $10,000 flagship power amp was really designed in mind for a complete Yamaha 5000 series system with their NS-5000 speakers. If you want a warmer sound with arguably the nicest build quality in the industry with ultra low noise you should also give Accuphase Class A a look like the A-48 also priced the same as the Yamaha 5000.

 

All Bryston amps have adjustable gain settings for SE or XLR input and pro models even have trim pots on the back.

 

Amp pairing and digital front end electronics are even more critical on high efficiency speakers both for noise and how revealing they are showing off a particular components sonic characteristics for better or worse!

 

I agree with the above that the higher power A/B Pass Labs amps by default are designed more in mind for lower efficiency conventional "box" speakers. Although I didn't know they offered a custom factory service when ordered new to tailor the gain for the customer, I agree the more "devices" in the amplifiers output stage path, the more distortion and noise that can get in there that won't get on well with horns. Heritage is super revealing of the front end electronics and can highlight the sonic differences between amp types and the house sound of various amp makes.

[Troll]

3 hours ago, sixspeed said:

The low watt Class A Pass amps seem to work best for Heritage of all Pass' designs. New McIntosh is very quiet as well. Something like a MC-152 if you want to stick Class AB would be a nice choice. The MA5200 I had, non-autoformer was very quiet and sounded wonderful, it's essentially the integrated version of the 152. A MC-152 or Bryston 2.5B3 would be on my personal shortlist if I were you. Both are direct competitors and priced the same in the $4800-5500 price point. Bryston has a 20 year warranty guarantee on all their analog gear. Yamaha I agree makes some very nice amps but most are integrated amps and their $10,000 flagship power amp was really designed in mind for a complete Yamaha 5000 series system with their NS-5000 speakers. If you want a warmer sound with arguably the nicest build quality in the industry with ultra low noise you should also give Accuphase Class A a look like the A-48 also priced the same as the Yamaha 5000.

 

All Bryston amps have adjustable gain settings for SE or XLR input and pro models even have trim pots on the back.

 

Amp pairing and digital front end electronics are even more critical on high efficiency speakers both for noise and how revealing they are showing off a particular components sonic characteristics for better or worse!

 

I agree with the above that the higher power A/B Pass Labs amps by default are designed more in mind for lower efficiency conventional "box" speakers. Although I didn't know they offered a custom factory service when ordered new to tailor the gain for the customer, I agree the more "devices" in the amplifiers output stage path, the more distortion and noise that can get in there that won't get on well with horns. Heritage is super revealing of the front end electronics and can highlight the sonic differences between amp types and the house sound of various amp makes.

 Sure one might say the Yamaha 5000 series with fully balanced and floated signal chain is designed to go together, but from personal experience with both RX-A8A and M-5000 A/B tested with NS-5000s and AL5s, the AL5s are night and day different and top dog, and the NS-5000s actually need the PEQ of the RX-A8A or other to get the most out of them.  While the unadulterated 5000 chain is quite true to historical sound of say Fleetwood Mac and Led Zeppelin vinyl, if I want anything similar to what the AL5s produce with the band Yello, I’ve got to tweak the NS-5000s using something more than just what the C-5000 tone controls offer.  But there’s nothing to the statement that the M-5000 is “matched” to the NS-5000 when looking at specs and hearing A/B differences with AL5s.  The M-5000 is an exceptionally clean and powerful amp conservatively rated with lots of reserve.  The RX-A8A high slew rate amps are also crystal clear.  The only difference I note on both the NS-5000 and AL5s when switching between M-5000 and RX-A8A amps is just the force and loudness, the bass is identical until you get to concert levels then the M-5000 slams effortlessly.  Anyway my ear votes Yamaha amps regardless of speaker, but I do tweak with PEQ and other methods to suite the genre and speaker.  The NS-5000s are my eye candy but the AL5s are my ear candy.  Honestly can’t say anything about other amps though I have only had Denon/Sony and now Yamaha, and I have heard McIntosh and Crown.  I was floored when I went from 27 watt Denon to Sony years ago, enjoyed the slam from extra power but missed the delicate highs of the Denon, and now I believe I have both with the Yamahas and great fiddle tools.  If the M-5000 was actually tuned to the NS-5000 it wouldn’t play flat out of the box.  Just saying. 
 

The Bryston 28 lbs, Yamaha 60 lbs, McIntosh 75 lbs, the signal to noise ratio is in the same order, but no way would I consider the Bryston model a competitor of these.

Edited July 7, 2023 by Stephen Buck

[OO1]

13 hours ago, Shakeydeal said:

Technically it’s still not zero.

I would venture a guess that they do measurements like most of the SS amps did, only at 1K.  

nope , 0.005   is 0.00 in mathematical terms ,

FYI  ,   the measurements  of no more than 0.005 per cent total harmonic distortion ... of the Sansui AU-D11  amplifier’s rating of 120 watts per channel into 8-ohm loads  is from 10 to 20,000 Hz  and definitely not at  1KHz ,    1-2 wpc  with this  120wpc amp  with  Heritage speakers    will have 0  distortion  .

 

 

[Marvel]

On 7/7/2023 at 8:19 AM, henry4841 said:

I have a grandson that can hear a dog whistle

I had a dog that could whistle a couple Doc Watson songs.

[OO1]

On 7/7/2023 at 8:19 AM, henry4841 said:

I have a grandson that can hear a dog whistle 

is he also  left-handed ?