250w vs 500w amps

[dodgnofski]

Hi Guys,

In terms of loudness/decibels - just how much louder is a 500w amp than a 250w amp?? - I can remember reading somewhere that it would take a 1000w amp to be twice as loud as a 100w amp??

Thanks

[Phil Starr]

3dB louder

noticeable but not by much.

Try this [url="http://www.ultimate-guitar.com/columns/gear_maintenance/making_it_loud.html"]http://www.ultimate-guitar.com/columns/gea...ng_it_loud.html[/url]

Cheers

[dodgnofski]

Thanks Phil,

Appreciated

All the best

Tim

[warwickhunt]

Not much difference but in real terms it's a little uncomfortable when you have a 250w amp virtually max'd... a 500w amp at the same 'perceived volume' just feels better. I've first hand experience of this (inc' quite recently) and I have to say it isn't nice when you know you are clipping your 250w amp to get enough volume; switching to a 500w amp (mid gig recently) and it does feel like you have the potential to go almost twice as loud even though the maths of it dictates that it can't be the case!

[xgsjx]

Here's a Q...

If you a LM250 & an LMII & you put a 2x10 4Ω cab on the LM250 & the same make & model of cab, but 8Ω on the LMII, would there be any noticeable differences (I know the LMII puts out more than 250w @ 8Ω, but is it gonna make a noticeable difference)?

I'm guessing yes as the LMII will still have that little more.

So best idea would be to sell the hypothetical 4Ω cab & get another identical 8Ω one so more air can be moved!

[warwickhunt]

[quote name='xgsjx' post='1253492' date='Jun 2 2011, 08:39 AM']Here's a Q...

If you a LM250 & an LMII & you put a 2x10 4Ω cab on the LM250 & the same make & model of cab, but 8Ω on the LMII, would there be any noticeable differences (I know the LMII puts out more than 250w @ 8Ω, but is it gonna make a noticeable difference)?

I'm guessing yes as the LMII will still have that little more.

So best idea would be to sell the hypothetical 4Ω cab & get another identical 8Ω one so more air can be moved! [/quote]
The first part... very little difference (iirc the LMII puts out 300w @ 8ohms).

The second part... x2 8ohm cabs with hypothetically double the number of drivers as a single 4ohm cab (I am assuming here that you aren't talking about comparisons between say a 4x10 4 ohm cab and a pair of 1x10 cabs or something equally mismatched) will certainly move more air and would be my preferred option. However, if you are talking about comparisons between say a single 2x12 4 ohm cab and a pair of 1x12's @ a combined ohmage of 4 ohms then I wouldn't say there'd be much difference ESPECIALLY if you are comparing cabs from the same manufacturer (Aggie DB212 v Aggie DB112 x2).

[ZMech]

On top of this, you then have the issue of the speaker sensitivity. Every cab with have a dB @1W rating thing that I don't really understand or pay attention to, although I think the barefaced cabs aremeant to be super good for this.

[alexclaber]

Technically it's 3dB which isn't much, but in practice it can make the difference between infrequent light clipping (which happens all the time with bass rigs and sounds fine) and more frequent heavier clipping which can sound nasty (in a bad way). Lots to read about this in the tech info and BGM articles on the Barefaced site. I'd take most sensitivity specs with a whole bucket of salt!

[Happy Jack]

[color="#FF0000"][b]*** PEDANT ALERT ***[/b][/color]

I'm struggling with the notion that "[i]infrequent light clipping[/i]" is something that "[i]happens all the time[/i]".

Maybe my version of "[b][i]infrequent[/i][/b]" needs updating or re-booting or something.

[alexclaber]

Replace "all the time" with "the vast majority of reasonably loud rehearsals or gigs"...

[xgsjx]

[quote name='warwickhunt' post='1253519' date='Jun 2 2011, 09:05 AM']The first part... very little difference (iirc the LMII puts out 300w @ 8ohms).

The second part... x2 8ohm cabs with hypothetically double the number of drivers as a single 4ohm cab (I am assuming here that you aren't talking about comparisons between say a 4x10 4 ohm cab and a pair of 1x10 cabs or something equally mismatched) will certainly move more air and would be my preferred option. However, if you are talking about comparisons between say a single 2x12 4 ohm cab and a pair of 1x12's @ a combined ohmage of 4 ohms then I wouldn't say there'd be much difference ESPECIALLY if you are comparing cabs from the same manufacturer (Aggie DB212 v Aggie DB112 x2).[/quote]
It is @ 300w - 8Ω.

My 2nd part was all cabs being identicle specs bar ohmage (wasn't intended to be a question tho ).

[MuckedUpFunkies]

I could be wrong but I was told wattage means very little which is why some 100watt amps (e.g. Old Peavy) sound so loud. Its more about the transformer which increases how quickly the maximum wattage can be pushed out or something like that? Dont take my word for it though =L

[OzzyGreg]

.
alexclaber,

Please check your PM box.

Cheers,
Greg

[Bill Fitzmaurice]

[quote name='alexclaber' post='1253585' date='Jun 2 2011, 04:49 AM']I'd take most sensitivity specs with a whole bucket of salt! [/quote]
More like a lorry load.
Doubling power gets you 3dB. Doubling your cab count gets you 6dB with the same amp. Unless your amp is severely underpowered, as in 1/4 or less than the power rating of your speakers, adding a second identical cab will usually be the better route.

[dodgnofski]

Thanks Guys,

All donations gratefully received

[chrismuzz]

I used to have a 300w Laney combo, unless i added an extention cab I could never get enough volume even at rehearsal levels. Even then it farts out a bit. Now using my 500w head through a single 8ohm cab (probably getting about 300w if i'm lucky), i don't even have to turn up halfway to be heard on most gigs without PA support! I suppose wattage has somethiing to do with it, but it depends how efficient the gear you're using is too. For example I get nowhere near the same volume with a 4 ohm ampeg 610 as i do with an 8 ohm markbass 410!

[Lozz196]

I think the efficiency of the cab is a definate factor. I`ve now got a single Eden Nemesis 410, which the efficiency is stated at 104 db. I previously had 2 Ampeg cabs, a 410 & 210, both at 99 db, and as chrismuzz above, my 410 getting 300 watts from my old TC Classic 450 was as loud as the 2 Ampegs getting the full 450 watts from it.

And I remember Laney combos well - used to have a Linebacker, one single 15 inch speaker. I used to have to hit the strings soooo hard to be heard, probably developed my ham-fisted playing technique from that amp.

[ficelles]

[quote name='alexclaber' post='1253585' date='Jun 2 2011, 09:49 AM']Technically it's 3dB which isn't much,[/quote]

Not everyone gets the logarithmic scale thing:

+3dB is double the power which is actually quite a lot - your second identical Marshall stack at full volume only adds 3dB to your first Marshall stack at full volume, but I think you'd notice the difference.

+6dB is double sound pressure level. I think that means we have 4 identical Marshall stacks all working flat out now. *

+10dB is double perceived loudness. Doesn't bear thinking about on the Cranked Identical Marshall Stack (CIMS) scale

* You can't always get +6dB just by adding speakers - you have to add power to drive them as well. Of course when you add a speaker in parallel you reduce the overall load and therefore get more power out the amp (P = VI). But if you add in series you will reduce the power and get less.

ficelles

Edited June 17, 2011 by ficelles

[alexclaber]

Close but not quite!

3dB is twice the power. But adding a second cranked Marshall stack to your first cranked Marshall stack wouldn't be this, as by adding a whole extra stack you're not jus doubling the power, you're also doubling the speakerage, with the end result being twice the displacement - or 6dB. 3dB difference would be going from a 100W Marshall head cranked into a big pile of cabs (so that the cabs aren't the limiting factor) to a 200W head into the same stack.

6dB is indeed twice the SPL, so that's twice the physical sound pressure level.

10dB would be perceived to be twice as loud if our ears were perfect. However they aren't, so only at 1kHz does a change of 10dB give you a doubling or halving of perceived loudness. It isn't that far off but it does mean that gaining ~6dB in the lows by adding a second matched cab for a doubling of excursion limited power handling, improved sensitivity (through coupling) and reduced impedance (thus more power from the amp) can result in your lows doubling in loudness (a 10 Phon increase).



Regarding the importance of sensitivity specs when trying to work out what will be loudest, that would be quite correct if the specs were accurate. Unfortunately very few are!

To further complicate matters we're all using different bass tones, so if a cab has a hump in response where one player likes a big part of their sound to happen but a dip in response where another player likes to punch through the mix, the former player will think that cab is loud whilst the latter player will think that cab is quiet! Which is why all anecdotal evidence needs to be taken with a further punch of salt... Indeed, Lozz's "104dB" Eden vs the 99dB Ampegs is most probably a case of that. Likewise chrismuzz's example of 6x10" Ampeg vs 4x10" Markbass. The cab with the loudness where that player wants it is the louder cab - but only for them!

[JTUK]

[quote name='ZMech' post='1253535' date='Jun 2 2011, 09:21 AM']On top of this, you then have the issue of the speaker sensitivity. Every cab with have a dB @1W rating thing that I don't really understand or pay attention to, although I think the barefaced cabs aremeant to be super good for this.[/quote]


Not sure about this. If you have to use a very hi powered amp to make any noise with a 300-400 watt speaker, that hardly suggests efficiency IMO.

If you tune the cab to produce low-end at the expense of volume..therefore needing lots more of it..that is the trade-off which is not much good to you if you have to buy another amp.

A very expensive way of doing things..???

[alexclaber]

Our honest and accurate sensitivity specs are all here: [url="http://barefacedbass.com/uploads/barefaced-cab-specs-jan2011.jpg"]http://barefacedbass.com/uploads/barefaced...ecs-jan2011.jpg[/url]

The LF sensitivity of the EMS cabs is inline with expected sensitivity for a high quality cab of that size (not weight). The LF sensitivity of the Big Series cabs is lower because they go lower. The broadband sensitivity of the EMS cabs is higher than usual for a high quality cab of that speaker configuration. The broadband sensitivity of the Big Series cabs is slightly lower but their strong off-axis response means they're louder than an on-axis measurement suggests.

So to put things more clearly - the Big Series cabs are designed (not merely tuned) to produce unusually deep lows without being proportionally larger, hence they need more power to reach a given volume. However because they can handle this power you can use a single Barefaced 2x12" to produce as much output and more bottom than a single normal 4x12".

The EMS cabs absolutely do not need more power - they're designed to have similar response to more typical bass cabs, similar LF sensitivity, greater broadband sensitivity and vastly greater power handling, so you can use fewer/smaller cabs and take full advantage of the high power amps which are everywhere (like 300W+). Clearly if you wish to go smaller then you will need more power to reach a given SPL in the lows - that is an inescapable law of physics!

Power is cheap. Many bassists have more power than their cabs will actually let them use (despite what the thermal power handling specs suggest). Our cabs let them use that power.

[ficelles]

[quote name='alexclaber' post='1272425' date='Jun 17 2011, 09:27 AM']10dB would be perceived to be twice as loud if our ears were perfect.[/quote]

I can't believe I didn't say 10dBA. They'll have my IOA card back

ficelles

Edited June 17, 2011 by ficelles