Add On's

[Ibanez Bassist]

I have an Acoustic B-100 Bass amp and in the back there is an out for another monitor but its 4 ohms.. this doesn't seem to be a common thing to find. do I really need a 4 ohm passive monitor for this port.. I appreciate any help Thanks Scott

[billfitzmaurice]

Originally Posted by Ibanez Bassist

I have an Acoustic B-100 Bass amp and in the back there is an out for another monitor but its 4 ohms..

Is it 4 ohm only or 4 ohm minimum? In any event you should use an extension of the same impedance as your existing speaker.

[Ibanez Bassist]

It specifically says its for a passive 4 ohm monitor as an add on or extension to the orig. I guess giving you a second speaker or monitor..

[anderbass]

The info from acoustic: http://www.acousticamplification.com/products/b100.cfm states the extension speaker jack is a series type, not parallel. (for more info, check out the ohm facts here about connecting cabs in series)

They're implying your combos internal speaker is a 4 ohm, and the 2 acoustic brand extension cabs they recommend using with your combo are both 8 ohm models, so I'd say It'd be safe to use 4 or 8 ohm extension cabs with your combo as long as your combined ohm load ended up at 4 ohm or above.

[billfitzmaurice]

Originally Posted by anderbass

The info from acoustic: http://www.acousticamplification.com/products/b100.cfm states the extension speaker jack is a series type, not parallel. (for more info, check out the ohm facts here about connecting cabs in series)

They're implying your combos internal speaker is a 4 ohm, and the 2 acoustic brand extension cabs they recommend using with your combo are both 8 ohm models, so I'd say It'd be safe to use 4 or 8 ohm extension cabs with your combo as long as your combined ohm load ended up at 4 ohm or above.

That being the case an 8 ohm extension raises the total load to 12 ohms, which is a bit much for a 100 watt/4 ohm rated amp to push. If the extension should be 4 ohms the recommended 8 ohm cabs shouldn't be.

[Ibanez Bassist]

I had someone else tell me that if I had an 8 ohm amp/speaker and put a 4 ohm external or add on to it that would be fine but dont do it the other way around you cant have a driving force of 4 ohm as your orig. and put an 8 ohm on it he said you might see smoke.. so I really dont know..

[Justice]

looking at the manuals on the site, it does not say but it is quite possible that using the external speaker jack disables the internal speaker. This would explain the 4ohm mim load for the external.

[Ibanez Bassist]

I have the orig. book and it does not disable the orig. 15" speaker this port is to add another monitor for personal use or to liven up another part of the room.. the orig. speaker is 4 ohms and I had someone tell me putting an 8 ohm passive on it would not be a problem but some how Im a little skeptical

[SurferJoe46]

The Acoustic combo is rated to use another (single) 8-Ω cab, and the suggested cabs are either the B-115 OR the B-410.

EDIT IN PROCESS!

OK - I think this is a little more clear:::

The only time you will get to the full-rated output is when you have the impedance at the minimum-rated Ohms capacity; your combo/cab is not at that value with just the legacy driver if 'industrial standards' are the norm here.

What does their Official Site actually say?

POWER: 100 Watts @ 4 Ohms
SPEAKER: 15" Heavy-Duty Speaker
CHANNELS: 1
EQ: 4-Band EQ - Sweepable Frequency Notch Filter
INPUTS: Dual Inputs (Passive & Active)
OUTS: Effects Loop, Ext. Speaker

OPTIONS: B115 1x15 Bass Cabinet ~ B410 4x10 Bass Cabinet

The series extension speaker jack provides an output for an additional cabinet such as the Acoustic® B115 or B410.

This is just confusing though as the word 'additional' creates the aura that you will have two drivers running at the same time - or maybe not. !

IF the legacy driver is still running you will then have both it and the aux cab running at the same time - and that seems normal.

Since 8Ω + 8Ω = 4Ω in a parallel circuit, this is what the unit will handle. This is within-design-limits for the B-100 and pretty much for any Acoustic cab that also has an output jack to utilize.

But if this is a series/parallel system - which I seriously doubt would be done here for all the extra wiring and dual-impedances or whatever - it still makes little sense.

4Ω is the minimum Ohm ratings that this B-100 amplifier can safely handle. That's kinda typical for this brand's smaller amps.

So - 8Ω is still within the values of this particular combo, since the legacy driver is 8Ω anyway - 'cause I don't see Acoustic having both 4 & 8Ω drivers in the same factory or in the same parts room. .

The problem is this::

<snip> They're implying your combos internal speaker is a 4 ohm, and the 2 acoustic brand extension cabs they recommend using with your combo are both 8 ohm models.....</snip>

'Implications' are not the fact and are just a guess. FYI: a single Acoustic 15" driver is 8Ω, so what's to 'imply' that the legacy driver is any more/less?

Clear as mud - huh?

The second part of the OP that catches my attention is this:

ibid: (a) 15" speaker this port is to add another monitor for personal use or to liven up another part of the room..

Can you define "another part of the room"? Just where do you advise placing the 'monitor'?

I believe this above (^) information is accurate - at least it complies with the official site's information --- I believe.

I'd give it the smoke test and if it fails, then you have a legally good argument to say you were just following instructions.

I like my Acoustic gear, and I don't like seeing this so open-ended; it just looks bad in a PR-way.

[swspiers]

Yeah.

They're in series.

So my 8 ohm B115 extension cab takes the impedence to 16 ohms (edit oops: 12 ohms), and my effective power down to somewhere around 70 to 100 watts. Yaaay me for not catching that when I bought the B200 combo.

[Bass_Pounder]

SurferJoe - nicely worded and thought out post above - but the assumptions and conclusions are incorrect.

Here is the manual:

http://www.acousticamplification.com...anual_B100.pdf


Go to page 11 of the manual, and look at the diagram.

It CLEARLY states that the internal speaker is 4 ohms, giving full power to the internal speaker.

It also CLEARLY states that the extension speaker jack is wired in SERIES with the internal speaker.

[SurferJoe46]

Yup! Sure looks that way.



So - 4Ω + 8Ω = 6Ω

OOOOPPPPSSS! My bad! Make that 12Ω

Sometimes, SurferJoe just grabs a bummer wave.

Not the most optimal methinks!

Originally Posted by Bass_Pounder

SurferJoe - nicely worded and thought out post above - but the assumptions and conclusions are incorrect.

Here is the manual:

http://www.acousticamplification.com...anual_B100.pdf


Go to page 11 of the manual, and look at the diagram.

It CLEARLY states that the internal speaker is 4 ohms, giving full power to the internal speaker.

It also CLEARLY states that the extension speaker jack is wired in SERIES with the internal speaker.

[Bass_Pounder]

Hate to keep correcting you, but in series 4 ohm + 8 ohm = 12 ohms.

That is probably why the ext. speaker jack is labeled for 4 ohms. Then it would match the impedance of the internal speaker, and give the amp a total load of 8 ohms.

[SurferJoe46]

Originally Posted by Bass_Pounder

Hate to keep correcting you, but in series 4 ohm + 8 ohm = 12 ohms.

That is probably why the ext. speaker jack is labeled for 4 ohms. Then it would match the impedance of the internal speaker, and give the amp a total load of 8 ohms.

You're right again... this is all before coffee and breakfast.

I just 'assumed' it was parallel - AGAIN!



It's pretty in pink though - wot?

[Ibanez Bassist]

Wicked good info. as always LOL So bottom line is I have to use ( or should use ) the recommended Acoustic brand Cabs ( B-115 or B-410 ) to attach to my B100 to get another monitor in the room.. I actually just wanted to grab a small passive 8 ohm wedge and stick it at the feet of the Keys player but might not be able to do that..
Thanks for the info..

[SurferJoe46]

I don't think you'd be limited on brand for an extension cab - I would worry about having a wedge that cannot handle the lows though.

Having a combo facing one way and a wedge facing back at you might be interesting in a 'sonic' way of course.

Watch out for phasing problems - and post the results though!

Now - if you can find a 2Ω extension cab - that would be interesting!

[Ibanez Bassist]

Im going to look into it a little more before I do anything, but definitely taking some great info from you guys with me.. hope it works out..

[Bass_Pounder]

Originally Posted by Ibanez Bassist

Im going to look into it a little more before I do anything, but definitely taking some great info from you guys with me.. hope it works out..

I would NOT do it if you are going to place the second cab away from your combo...............

In a series connection, your wattage is going to get cut in half at least (if using a 4 ohm extension - even more of a power cut if you use an 8 ohm extension).

Cutting your power in half results in a -3db drop in output. However, if you double your speaker area you pick up +3db due to sonic coupling of the speakers. So it becomes a tradeoff of less power strain on the amp to produce the same levels (in theory).

If you place the second cab AWAY from your combo, you will lose out on the sonic coupling, and only realize a big drop in the output you will hear.

[RickenBoogie]

the acoustic combo's are not well thought out, since a series ext spkr jack drops the power. So, though you gain volume with the added spkrs, you also lose power. Not the best.

[Ibanez Bassist]

Thats interesting, I dont think that got mentioned yet here.. I will look into that as well, this whole thing might not even be worth trying to do with everything thats said.. the thing is now I have a mic in front of my B-100 and the sound from that is tied into an active 200 Watt 12" monitor which is OK but I was trying some how to do away with the Mic situation thats all.. so I figured I would use what they gave me on the back of the B-100 but now I dont know ??