Using two cabs rather than one.

[bass_ferret]

Yes the amp only sees a 4 ohm load, but each 8 ohm cab will get half of the watts. The amp does not care whats in the cab - its an 8 ohm cab.

[Protium]

[quote name='bass_ferret' post='366505' date='Dec 30 2008, 06:57 PM']Yes the amp only sees a 4 ohm load, [b]but each 8 ohm cab will get half of the watts[/b]. The amp does not care whats in the cab - its an 8 ohm cab.[/quote]

Why? It's a single circuit:

[attachment=17864:wiring2.JPG]

How does the amp know which is the 410 and which is the 115 and thus where to split the power?

[bass_ferret]

Your drawing is wrong. You have each pair of 10's in parallel with the 15. They are both in parallel with the 15. I cant do this drawing sh*t but the lines from the sides to the 10's are wrong - there should only be one and then the 10's are parallel within that.

[Bill Fitzmaurice]

[quote name='Protium' post='366534' date='Dec 30 2008, 02:36 PM']How does the amp know which is the 410 and which is the 115 and thus where to split the power?[/quote]
It doesn't know, and it doesn't split the power. Each cab will receive the same voltage. How much current each cab will receive is decided by each cab's impedance; with equal impedance the amount of current into, and therefore the power dissipated by each cab, with be the same.
[quote]the lines from the sides to the 10's are wrong[/quote]If they are four 8 ohm drivers wired series/parallel for a total 8 ohm load the drawing is correct.

Edited December 30, 2008 by Bill Fitzmaurice

[bass_ferret]

My Brain Hurts and I am not explaining myself very well !!!!!!!!!!!!!!!!

On the drawing each pair of 10's is shown as a separate parallel connection to the 15. But its not. The two pairs of 10's are wired in parallel, and then the whole 2 x parallel 10's are in parallel with the 15. Thats why Protium thinks the 15 and each pair of 10's gets a third of the amps beans.

[Born 2B Mild]

I don't understand most of this, but I love watching this Techno Tennis

[Bill Fitzmaurice]

[quote name='bass_ferret' post='366578' date='Dec 30 2008, 03:26 PM']My Brain Hurts and I am not explaining myself very well !!!!!!!!!!!!!!!!

On the drawing each pair of 10's is shown as a separate parallel connection to the 15. But its not. The two pairs of 10's are wired in parallel, and then the whole 2 x parallel 10's are in parallel with the 15. Thats why Protium thinks the 15 and each pair of 10's gets a third of the amps beans.[/quote]
Electrically the diagram is correct. Electrons pay no mind to whether the 10s are in one box and the 15 in another. Since each paired set of tens is series wired those pairs each offer a 16 ohm impedance to the amp, so those pairs will each receive only half the current that the 15 does.

[Protium]

[quote name='Bill Fitzmaurice' post='366666' date='Dec 30 2008, 10:19 PM']Electrically the diagram is correct. Electrons pay no mind to whether the 10s are in one box and the 15 in another. Since each paired set of tens is series wired those pairs each offer a 16 ohm impedance to the amp, so those pairs will each receive only half the current that the 15 does.[/quote]

Thank you for explaining this

Also thank you for explaining the current/impedance/voltage/power rather than just putting "YOU ARE WRONG"

Edited December 30, 2008 by Protium

[bassmachine2112]

hiho,my head hurts

[bass_ferret]

[quote name='Bill Fitzmaurice' post='366666' date='Dec 30 2008, 10:19 PM']Electrically the diagram is correct. Electrons pay no mind to whether the 10s are in one box and the 15 in another. Since each paired set of tens is series wired those pairs each offer a 16 ohm impedance to the amp, so those pairs will each receive only half the current that the 15 does.[/quote]
Thanks Bill. Knew I was missing something obvious I was thinking physical rather than logical

[bass_ferret]

[quote name='Protium' post='366683' date='Dec 30 2008, 10:39 PM']Thank you for explaining this

Also thank you for explaining the current/impedance/voltage/power rather than just putting "YOU ARE WRONG" [/quote]
Cant see any posts that just say "YOUu ARE WRONG"

[TimR]

All this talk of 15" and 10" and power into each driver is all very well. These are 'nominal' impedances and power ratings. Using ohms law and DC is OK but in reality the impedance of each speaker varies at different frequencies. The impedance of the 10" is unlikely to be the same as the impedance of the 15" for any given frequency so the power distribution will be much more complex than just saying 225watts and 4x56.25watts.

But all they give us is nominal figures so fag packet drawings and schoolboy physics are the way to go, and are ok if all you are interested in is whether your speakers or amp will blow first.

E.G. say the 10"s were 25ohms at 40hz and the 15" was 15ohms at 40 Hz, what happens to the power distribution then? How much of that amp power is going to get used at 40Hz and where will it go?

Since the 15" is more likely to have a lower impedance for a given frequency than the 10s, a good deal of your power is likely to go in the direction of the 15".

That's just electrically, never mind what then happens acoustically.

This is why mixing drivers doesn't always sound good, even 2x15" from different manufacturers. Regardless of what you think the specs say, your ears are your friend.

[warwickhunt]

[quote name='TimR' post='370459' date='Jan 4 2009, 10:44 PM']All this talk of 15" and 10" and power into each driver is all very well. These are 'nominal' impedances and power ratings. Using ohms law and DC is OK but in reality the impedance of each speaker varies at different frequencies. The impedance of the 10" is unlikely to be the same as the impedance of the 15" for any given frequency so the power distribution will be much more complex than just saying 225watts and 4x56.25watts.

But all they give us is nominal figures so fag packet drawings and schoolboy physics are the way to go, and are ok if all you are interested in is whether your speakers or amp will blow first.

E.G. say the 10"s were 25ohms at 40hz and the 15" was 15ohms at 40 Hz, what happens to the power distribution then? How much of that amp power is going to get used at 40Hz and where will it go?

Since the 15" is more likely to have a lower impedance for a given frequency than the 10s, a good deal of your power is likely to go in the direction of the 15".

That's just electrically, never mind what then happens acoustically.

This is why mixing drivers doesn't always sound good, even 2x15" from different manufacturers. Regardless of what you think the specs say, your ears are your friend.[/quote]

Well hello and welcome Tim! Your stand on 'technical' V's 'real life' is duly noted and you might find that you even have allies when it comes to NOT mixing drivers but where do you stand on 'vintage bass' V's 'just a load of old tat'?

[TimR]

[quote name='warwickhunt' post='370495' date='Jan 4 2009, 11:23 PM']Well hello and welcome Tim! Your stand on 'technical' V's 'real life' is duly noted and you might find that you even have allies when it comes to NOT mixing drivers but where do you stand on 'vintage bass' V's 'just a load of old tat'? [/quote]

Thanks for the welcome.

Sorry. I don't mean to make a stand on mixing drivers. Just as long as it sounds musical, but just adding a 15" or a 4x10" thinking it will sound better, isn't always the case, and using power ratings to judge whether a speaker will sound good is not a good idea. (I had a 15" and added a 2x10". Not only did it sound really terrible but it was quieter too!)

I'm obviously new here and have only lurked a bit, but thought I throw something to think about into the pot. I guess the mixing drivers discussion must come up fairly regularly then.

vintage bass v's a load of old tat? Well I can only play old tat as I'm not old enough or rich enough to have a vintage bass, just some old tat from the 80's and something from the last millennium

[Bill Fitzmaurice]

[quote name='TimR' post='370459' date='Jan 4 2009, 05:44 PM']All this talk of 15" and 10" and power into each driver is all very well. These are 'nominal' impedances and power ratings. Using ohms law and DC is OK but in reality the impedance of each speaker varies at different frequencies.[/quote]
SS amps are constant voltage devices, no matter what impedance they see the voltage output is a constant. Current, and therefore power, does fluctuate with the load, but drivers are also voltage dependent devices, and will put out a constant dB level with a given voltage input, irrespective of current/power. Things aren't so cut and dried with valve amps, but for all intents and purposes impedance versus frequency is still for the most part a non-issue. And a good thing that is, otherwise no dynamic driver would be usable, what with every note coming forth at a different volume level.

[The Funk]

[quote name='ritch' post='365512' date='Dec 29 2008, 03:06 PM']Now, something that took me by surprise, was when i put my head infront of each cab, the 1x15 'sounds' louder than the 4x10. I think I was expecting the 4x10 to create more of the sound as it has more speakers and probably moves more air (maybe).

Has anybody else had a similar experience with a similar set up? Is this what I should expect?[/quote]

First off, stop putting your head in front of bass cabs!

Secondly, yeah, when I had a Hartke 2x10 and 1x15, the 1x15 was louder - because I had a 2-channel power amp, I could adjust the levels of each cab to match. When I just ran through a head into the cabs, the 2x10 was a little subdued in comparison. (The 1x15 had a higher sensitivity rating than the 2x10).

Edited January 5, 2009 by The Funk