4b st...extra power

rmurray · « **Reply #40 on:** 21 Sep 2011, 07:29 pm »

Thanks James. Only curious. Does this reflect changes in transformers or caps from various model years. I still happy to have the extra overhead...

James Tanner · « **Reply #41 on:** 21 Sep 2011, 07:32 pm »

I will check further but yes it is simply the small differences between parts used through the amplification chain - especially power supply.

james

rofo · « **Reply #42 on:** 21 Sep 2011, 07:55 pm »

Quote from: rmurray on 21 Sep 2011, 03:56 pm

What is the reason for the various actual power outputs. ?

An amplifier is a gain device and is expressed as a ratio input vs. output and the gain is measured in decibels. A 4B is spec'd at having a gain of 29dB if you see the example above the gain of that particular 4B is about 29.5dB slightly over spec. The power rating is an indication of the load impedance of a specific amplifier can handle. An IC amplifier(s) can have a gain of 29 dB but the is no way it can drive and 8 ohm load as it doesn't have the ability to deliver the current, however if it sees a 20k load it is happy.
Got to think in dB.

SoundGame · « **Reply #43 on:** 21 Sep 2011, 08:14 pm »

Quote from: James Tanner on 21 Sep 2011, 07:23 pm

You realize you are talking about minuscule amounts of power differences from channel to channel which will never be heard!!

james

Agreed!

Real world, in-room performance will not be impacted by variations of this size in amplifiers with power ratings this high.

Typically, a doubling of power only gets you a 3db increase in volume, which is just noticeable.
You need 10 times the power to increase the volume by 10 db, which is a perceived doubling of volume.
A 10% increase in power, which is what were talking about here in most cases will result in a non-perceiveable volume increase - meaningless.

That all said - I believe though some get a kick out of having the higher stated / rated power.

I'm sure that if Bryston was to announce a 10% increase in rated power across all it's amplifiers, it would lead to an increase in sales - though probably no real increase in the volume levels attainable with the amplifier.

Consumers are funny like this. I get sucked into this myself from time to time.

rofo · « **Reply #44 on:** 21 Sep 2011, 08:27 pm »

Quote from: SoundGame on 21 Sep 2011, 08:14 pm

Typically, a doubling of power only gets you a 3db increase in volume, which is just noticeable.
You need 10 times the power to increase the volume by 10 db, which is a perceived doubling of volume.
A 10% increase in power, which is what were talking about here in most cases will result in a non-perceiveable volume increase - meaningless.

this is the exact thinking process that is required

redbook · « **Reply #45 on:** 21 Sep 2011, 10:54 pm »

Not about volume. It's about pressure at low volume levels.

spinner · « **Reply #46 on:** 21 Sep 2011, 10:58 pm »

Spare the tech crap , I hear what I hear................

rofo · « **Reply #47 on:** 22 Sep 2011, 01:08 am »

Quote from: redbook on 21 Sep 2011, 10:54 pm

Not about volume. It's about pressure at low volume levels.

Could you please explain I am not sure what you mean?

rofo · « **Reply #48 on:** 22 Sep 2011, 01:15 am »

Quote from: spinner on 21 Sep 2011, 10:58 pm

Spare the tech crap , I hear what I hear................

What do you mean to tech crap? are you referring to my post? If you are it is not tech crap it is the fundamentals of audio, as you say it is what you hear and is the way you hear.

Anonamemouse · « **Reply #49 on:** 22 Sep 2011, 07:06 am »

Quote from: James Tanner on 21 Sep 2011, 07:23 pm

You realize you are talking about minuscule amounts of power differences from channel to channel which will never be heard!!

james

Tsssk tsssk tsssk James...

We, Bryston owners and trained listeners, will MOST DEFINITELY hear 1 Watt differences!
I for one have always found that the sound on one channel was MUCH louder and hogging the soundstage! After switching the loudspeaker cables the other side was significantly louder!

I am deeply disappointed by this comment... As if we are half deaf or something...

spinner · « **Reply #50 on:** 22 Sep 2011, 08:34 am »

Yes, like that. I, for one,seem to sense something in these small power (current?)differences .Technical understanding is great as an objective measuring tool but I think we are confusing this with subjective perception. Each of us hear sounds differently . No amount of explaining things technically will ever be convincing solely on numbers .If that were the case we would be identical robots instead of the unique beings that we are.

rofo · « **Reply #51 on:** 22 Sep 2011, 02:27 pm »

Quote from: Anonamemouse on 22 Sep 2011, 07:06 am

We, Bryston owners and trained listeners, will MOST DEFINITELY hear 1 Watt differences!

It is all relative, you have to talk in terms of decibels "I increased the volume by 6dB which used and additional 5 watts of power" you wouldn't say "I turned the volume up by 5 watts". One additional watt of energy at very low levels will be a huge increase in volume, one additional watt of energy at high volume levels is insignificant. In this thread we are talking about additional power above the maximum specified power by the manufacturer. Remember it is a logarithmic scale. see below I hope this helps.

rollo · « **Reply #52 on:** 22 Sep 2011, 03:56 pm »

Quote from: Anonamemouse on 22 Sep 2011, 07:06 am

Tsssk tsssk tsssk James...

We, Bryston owners and trained listeners, will MOST DEFINITELY hear 1 Watt differences!
I for one have always found that the sound on one channel was MUCH louder and hogging the soundstage! After switching the loudspeaker cables the other side was significantly louder!

I am deeply disappointed by this comment... As if we are half deaf or something...

We had a similiar experience when switching cables. It was the cable. When we inserted a different pair no issues. One Watt

really ?

charles
SMA

Diamond Dog · « **Reply #53 on:** 22 Sep 2011, 04:40 pm »

Anonamemouse: Too hip for the room ?

D.D.

redbook · « **Reply #54 on:** 22 Sep 2011, 07:40 pm »

Rofo ,that's what I mean by low volume pressure. My speakers still present a sense of bass pressure at very low levels. Having that extra few watts must help.The 4b's 250 watts plus the bonus 60 ; works wonders in my sweet spot. Anyway thanks for that graph. It's all good.................

rofo · « **Reply #55 on:** 22 Sep 2011, 10:16 pm »

Quote from: redbook on 22 Sep 2011, 07:40 pm

Having that extra few watts must help.

You would think so but not really.
I am too dumb to understand technical crap but let’s look at a case.
I bought new speakers the sensitivity is 80dB (with 1 watt of power, the speaker produce a level of 80db one meter away)
I put on a CD and I sit one meter away from the speaker and my average listen level is 80dB (I know I'm too close and it is too loud). There a drum or symbol crash the transient spike is 12dB in order for my new speaker to produce 92dB the amplifier needs to deliver 16 watts. If this is going to me my listen environment 100 watt amp would be just fine. Perhaps I could buy a 3B and put the extra money I saved by not buying a 4B toward a new digital player.
My friend comes over with some beers and says "hay that’s a great CD start it over and crank her up". I turn it up so that the level is 92dB (averaging 16 watts) the 12dB transient now comes and in order for my speaker to produce 104dB the amp must provide 256 watts not a problem for my 4B. But I forgot about the 15dB increase from the dropped microphone during the live recording. In order to product 107dB we are asking the amp to deliver 512 watts my 4B clip lights come on and smoke comes from my tweeter, there goes my warranty.
As stated in a previous posting we can just start to detect and increase in volume when the level is increased by 3dB (going from 104 to 107). You can see that an extra 30 or 60 watts available from my 300 watt 4B is rather insignificant. But hay I’m still impressed and like to see that extra power on paper.

Mag · « **Reply #56 on:** 22 Sep 2011, 11:47 pm »

Well that's not how it works in practice. My spl listening ranges from 92-100 db, using a 3B SST & SST2 and I've never seen it clip. That's with 92 db speakers.

I've had my 3B ST clip prior to purchasing the SST's. So I'm guessing at peak volumes its using around 120 watts. However these amps are capable of much higher output for short duration.

rofo · « **Reply #57 on:** 23 Sep 2011, 01:13 pm »

Quote from: Mag on 22 Sep 2011, 11:47 pm

Well that's not how it works in practice.

Could you please elaborate and explain how it does work?
If you are right and it doesn't work that way every sound system in every stadium, arena, performance space, recording studio, etc. in the world has been engineered incorrectly. Yes an arena is not the same as your listening space but the physics is the same.
Using your example if you are 2 meters away from your loudspeakers and you are listening at a level of 92dB you are using 4 watts of power, lots of headroom left on your 3B.

Mag · « **Reply #58 on:** 23 Sep 2011, 04:00 pm »

Well I'm too dumb to understand the technical crap and I was never any good at math.

Ok, what really takes power is bass. Using a 3-way tower speaker that is capable of playing bass with some impact as an example. So a 92 db speaker is using 1 watt. Let's say bass takes double the power, but we have to consider the Fletcher Munson effect. So the bass is perceived at 87 db and we are using 2 watts. According to my calculation at 100 dbs of bass output I'd be using 64 watts, with a 6 db dynamic range I'd potentially need 246 watts for the transient peak. Within the amps power range.

With your 80 db speaker example I'd need 5672 watts.

A typical recording only has a dynamic range of 6 dbs. The only exception that I have is a Kodo cd, and yes I can damage my speakers if I'm not careful with the volume. Which is why I don't play it anymore.

redbook · « **Reply #59 on:** 23 Sep 2011, 04:20 pm »

Tech crap aside...After 12 years of regular use I'm yet to see any clipping lights activated. Maybe what I think is "loud" never really puts a demand on this great amp? At an eleven foot listening distance the JBLs just fill the area even at very low late night levels. I don't know what the spl is ,don't really worry,I just enjoy the effect.