15 posts / 0 new
Last post
craig84's picture
Offline
Last seen: 7 months 1 week ago
Joined: 19/11/2013 - 13:16
Posts: 58
8ohm 91dB - 6ohm 89dB

craig84's picture
Offline
Last seen: 7 months 1 week ago
Joined: 19/11/2013 - 13:16
Posts: 58
RE: 8ohm 91dB - 6ohm 89dB

what the bloody hell happend to my post!? :doh:

Oh well it basically said will i need to turn my Amp up much more on a 6ohm 89dB speaker than my current 8ohm 91dB speakers. I know dB is not a linear scale so was wondering if i would even notice the difference as my current Tannoys are pretty loud at just past 9oclock

Craig

Amp is 75wpc 651A which i assume is REAL watts as it blows my Arcam AVR 200 (90 Wpc) away

JamesMellor's picture
Offline
Last seen: 14 hours 15 min ago
Joined: 19/07/2013 - 15:45
Posts: 319
RE: 8ohm 91dB - 6ohm 89dB

Afaik a 3dB increase in SPL is twice as loud , but how this would relate to the precived volume of a speaker I don't know plus your ears adjust to the volume of the environment you are in , like a shout in a library or a shout the day after a Motörhead concert Smile .

But didn't you already demo your new speakers with your new amp ? , seem to remember reading you loved them 

James 

BigH's picture
Offline
Last seen: 57 min 12 sec ago
Joined: 29/12/2012 - 12:31
Posts: 3549
RE: 8ohm 91dB - 6ohm 89dB

You may have to increase the volume but that could be a good thing as many amps have a sweet spot often around 10-11.  But 3dbs is not a lot so don't worry about it.

Joshuamessenger's picture
Offline
Last seen: 5 months 3 weeks ago
Joined: 23/03/2012 - 20:59
Posts: 74
RE: 8ohm 91dB - 6ohm 89dB

It may have some thing to do with the recording level of the track. When I play mp3 I find one song a artist is louder than another. 

This could help but prob not  :s 

davedotco's picture
Offline
Last seen: 3 hours 48 min ago
Joined: 24/04/2013 - 10:02
Posts: 3088
RE: 8ohm 91dB - 6ohm 89dB

Ok, lets put some facts to this thread.

Sound pressure level (or just level) is a measurement of the variations in sound pressure. It is a measurable fact, just like feet and inches but measured in db. (strictly speaking the deciBel is a comparative measure, a ratio if you prefer)

In hi-fi the first thing that you need to know is that it is a log scale, ie 10db is ten times, 20db is one hundred times, 30db, one thousand times.

The second thing you need to know is that for a hi-fi system to be increased in level by 3db, you need the speaker to produce twice the acoustic output, ie the amplifier needs to produce twice the power. For the level to be increased by 10db, you need 10 times the power etc, etc.

Loudness (percieved volume if you prefer) is a subjective measure of how loud something seems to us. It is different for everyone but if we take the average results from a large group of people we get the following.

Most people can hear, as a change in loudness, a difference of 1db in SPL, that though, is under controled conditions in a test. A discernable change in loudness in a hi-fi system, in a normal environment, playing music is more likely to be closer to 2db. A clearly noticeable, significant change of loudness is likely to be 3db or more.

Twice as loud is usually considered to be a 10db change in measured level, though some research suggests about 8db more realistic for many people. These are subjective evaluations remember, a degree of spread is to be expected.

Back to the OP. The change in nominal impedence is difficult to judge, you would need to see the curves and know how to interpret them, but from the figures above, a 2db drop in sensitivity might not be much in terms of percieved volume but is significant in power terms, ie to maintain the same headroom your amplifier would need to be approx one and half times as powerful as for the more sensitive speaker.

alienmango's picture
Offline
Last seen: 3 months 2 weeks ago
Joined: 29/05/2013 - 17:22
Posts: 174
RE: 8ohm 91dB - 6ohm 89dB

Pretty generally as long as you're not cranking it past 12 'clock on a regualr basis this won't affect you.

 

Exceptions are heavily compressed music, arcam said the headroom could be used by loud signal/comprressed music combination by 10 O'clock.

You mentioned 9 is loud, so you shoud be fine.

 

davedotco's picture
Offline
Last seen: 3 hours 48 min ago
Joined: 24/04/2013 - 10:02
Posts: 3088
RE: 8ohm 91dB - 6ohm 89dB

alienmango wrote:

Pretty generally as long as you're not cranking it past 12 'clock on a regualr basis this won't affect you.

 

Exceptions are heavily compressed music, arcam said the headroom could be used by loud signal/comprressed music combination by 10 O'clock.

You mentioned 9 is loud, so you shoud be fine.

The volume control has no bearing whatsoever on the output levels (ie the wattage) being produced by the amplifier, the way a volume control operates is almost entirely at the whim of the designer.

Arcam are also talking rubbish, headroom is most easily used up by dynamic uncompressed material that drives the amp into clip even though average power remains at just a handfull or so watt.

Heavily compressed recording played loud may not have the peaks to clip the amplifier but the long term sustained power output might put a strain on the output stages or power supply, most often the latter.

craig84's picture
Offline
Last seen: 7 months 1 week ago
Joined: 19/11/2013 - 13:16
Posts: 58
RE: 8ohm 91dB - 6ohm 89dB

JamesMellor wrote:

Afaik a 3dB increase in SPL is twice as loud , but how this would relate to the precived volume of a speaker I don't know plus your ears adjust to the volume of the environment you are in , like a shout in a library or a shout the day after a Motörhead concert Smile .

But didn't you already demo your new speakers with your new amp ? , seem to remember reading you loved them 

James 

 

Hi James , yeah i did but it was in a nice new richer sounds demo room which was so acoustically dead it was as far away from my living environment as possible. i must say the Duo never sounded stressed.

Thanks to all your replies, when i have the money in my pocket i will definitely audition these against the DC6T SE's once more before i bite the bullet as £1000 dont come for free Blum 3

 

alienmango's picture
Offline
Last seen: 3 months 2 weeks ago
Joined: 29/05/2013 - 17:22
Posts: 174
RE: 8ohm 91dB - 6ohm 89dB

davedotco wrote:

alienmango wrote:

Pretty generally as long as you're not cranking it past 12 'clock on a regualr basis this won't affect you.

 

Exceptions are heavily compressed music, arcam said the headroom could be used by loud signal/comprressed music combination by 10 O'clock.

You mentioned 9 is loud, so you shoud be fine.

The volume control has no bearing whatsoever on the output levels (ie the wattage) being produced by the amplifier, the way a volume control operates is almost entirely at the whim of the designer.

Arcam are also talking rubbish, headroom is most easily used up by dynamic uncompressed material that drives the amp into clip even though average power remains at just a handfull or so watt.

Heavily compressed recording played loud may not have the peaks to clip the amplifier but the long term sustained power output might put a strain on the output stages or power supply, most often the latter.

 

It was talking about the rms ability of the amp, sustained playback at 11 o clock and above with compressed music caused it to overheat in my case, implying it was probably clipping too even if the clips wern't a long way above the rms of the music. 

 

This is true,  "the way a volume control operates is almost entirely at the whim of the designer." But few amps, if any, will be running near capacity at 9 o clock assuming a normal cd playerdac input. 

 

 

 

davedotco's picture
Offline
Last seen: 3 hours 48 min ago
Joined: 24/04/2013 - 10:02
Posts: 3088
RE: 8ohm 91dB - 6ohm 89dB

@Alien

There are several different issues here that interact and can cause confusion.

One of the big issues is the high output of CD players, Red Book requires a 2v output but many other source somponents interface at a much lower level, the volume control has to take acount of this.

Also some manufacturers like a volume control that 'gets loud very quickly', it impresses the novice buyer and combined with a CD player, particularly one designed with a slightly higher than normal output (quite common) it is quite possible that the amplifier is close to the limit at a volume setting around 9 - 10 o'clock.

Owners often do not understand this so so systems get overdriven and damaged though the volume might not be beyond 12 o'clock (half volume/power to many users, so therefore 'safe').

Another issue is the relationship between RMS power, peak power and dynamic range. For example, take a decent modern 50 watt amplifier, playing a good modern recording with a dynamic range of, say, 20db.

The amplifiers peak power capability is about 70 watts (1.414 x RMS power) so driven up to, but not into clip on our given recording, the RMS power being delivered by the amplifier is 10db down, or about 7 watts.

So in this example a decent amplifier would have a power supply sufficient to handle the musical peaks, some bursts of sustained power well beyond 7 watts and have output stages and heatsinking that can handle the long term sustained power that it is likely to be required to produce.

But, power supply transformers and capacitors are expensive as are high power transistors and especially heat sinking and if you are building an amplifier to go into a competitive market place, you really do not want to spend more on these items than you have to.

So, realistically, whatever the spec says budget amplifers are not going to be able to drive as hard as better specced and more expensive models, even if their rated power is the same and some will overheat due to inadequate heat sinking.

With some modern recordings with a dynamic range in single figures, the amp can be turned up louder without clipping and this sustained output may cause overheating or even failure and if this is bass heavy music, played with a bit of boost on the bass contol it is easy to see how this could happen with the volume control still at pretty modest levels.

Rethep's picture
Offline
Last seen: 23 hours 43 min ago
Joined: 02/05/2011 - 00:03
Posts: 330
RE: 8ohm 91dB - 6ohm 89dB

Imo your volumesetting has also to do with the character of the speakersound. If one sounds more "aggressive", it sounds "louder" too. So it's not only the difference in sensitivity. Anyway 89 or 91 dB is not a big difference.

As i know, In SPL, 6dB is known as a double volume to the ears!

davedotco's picture
Offline
Last seen: 3 hours 48 min ago
Joined: 24/04/2013 - 10:02
Posts: 3088
RE: 8ohm 91dB - 6ohm 89dB

Rethep wrote:

Imo your volumesetting has also to do with the character of the speakersound. If one sounds more "aggressive", it sounds "louder" too. So it's not only the difference in sensitivity. Anyway 89 or 91 dB is not a big difference.

As i know, In SPL, 6dB is known as a double volume to the ears!

The relationship between power, measured SPL and percieved loudness was covered earlier in the thread, see post 5.

In terms of measured SPL a 10db difference is double the pressure (SPL) and in terms of hi-fi this requires 10 times the amplifier power.

Percieved loudness ('volume to the ears) is a highly subjective measure and varies with the listener. Established scientific thought suggest that the 'average' person in tests will percieve a change of 10db as twice as loud.

This remains a subjective measure and some modern tests suggest that a change of 8db is more realistic but this is highly debateable.

A 2db difference is not a big percieved change in volume but in hi-fi terms it does require substantially more power from the amplifier, around one and a half times in fact.

6db is a substantial lift in SPL but to most people, nothing like twice as loud.

alienmango's picture
Offline
Last seen: 3 months 2 weeks ago
Joined: 29/05/2013 - 17:22
Posts: 174
RE: 8ohm 91dB - 6ohm 89dB

What we all need are those flickery watt guages from the 70's...    Dance 4

adamrobson's picture
Offline
Last seen: 8 months 1 day ago
Joined: 29/11/2013 - 13:33
Posts: 1
RE: 8ohm 91dB - 6ohm 89dB

I need goog hi fi for my vinyls help me

Log in or register to post comments