External speaker mod advice please?

[Ekko]

Hi -- I plan on buying an Acus "One For Bass" combo amp (solid state) for my baritone acoustic guitar. It's rated at 400w into a 4 ohm
woofer-plus-tweeter arrangement. For gigs, I would like to drive an additional external 4 ohm speaker from the amp. So my
plan would be to install a speaker connection output so that I could run the external speaker in series with the onboard
speaker/tweeter, thus drawing 200w from the amp (200w would be fine for the gigs I play). I'd be very grateful if anyone could alert
me to any potential problems in doing this.

[g1]

I don't see any problems, just make sure the jack is insulated from the chassis.
Is this a kit that already includes the internal speaker?
Otherwise you could use an 8 ohm internal and run another 8 ohm external in parallel. Then it would be 200W alone and 400W with ext.speaker.

[J M Fahey]

You can do what´s suggested above, but we were talking "500W Bass amps into **VERY** inefficient speakers" just a couple hours ago.
Your "400W amp into a single 10" speaker" certainly fills that description and then some.

Since I guess you will connect it to an external "real" speaker, thinking , say, 2 x 12" or 4 x 12" guitar speakers which are way more efficient and better suited for Guitar (even if a baritone one) I wouldn´t even waste power sending it into the internal speaker, but would rather add a switching jack or a regular jack and an added toggle switch: "Internal/External speaker" labelled, and send internal amp straight to the external speaker, be it 8 or 4 ohm.

A 4 ohm one will get full 400W, an 8 ohm one full 200W, while an external one in series with the internal one will get at most 100W , the rest being dissipated into the internal one.

Plastic/insulated jack suggestion still applies, of course.

[Enzo]

And the discussion is assuming the 400 watt amplifier sits there putting out a steady 400 watts. That isn't what happens.

[Ekko]

Thanks for your replies.

My proposed external speaker is a lovely-sounding (German) Echolette LE2 from the sixties -- in fact, I have three of these. Up till now I have been driving two of them from my SWR California Blonde acoustic guitar combo, with the whole rig set up behind me, so that I don't need monitors. Works and sounds great. Trouble is, the mighty Blonde weighs 50 Ibs and has limited effects and features, so that I'm having to use a small mixer as well. The Acus is very well-endowed in that department. Uniquely, it even has two channels with compressors, and each is adjustable for both threshold and ratio (I always like to use compression on my guitar and voice). Overall, it has a great sound, fantastic eq, stacks of volume, nice effects, and weighs just 28 Ibs. My ideal scenario is to drive one or more of my beloved Echolettes from the Acus. I enjoy experimenting, and I've found that the only way to decide these matters is give it a try -- but I do heed advice from those in the know concerning hazzards/damage that might arise in the process.

[J M Fahey]

PLEASE DON´T !!!!!!!!!!!!!!!!!!!!!!!

Those are 35W *tops* speakers, you will DESTROY them with your 400W amp.

"But I will never rise the volume knob above 3" ... famous last words.

Do-not-even-try .

As I said earlier, use the 400W amp to drive a 300/400W cabinet at least, or similar beefy speakers.

Use those Echolette speakers with an up to 50W Tube anplifier, what they were designed for.

You want flexibility and power?

Get one of those do-it-all pedalboards: Line 6 , VOX, KORG, Roland, etc. for unlimited sound palette, drive a couple full range powered speakers (think EON and such) and call it a day.

More versatile than even the ACUS, tons of power, very efficient, great projection, perfectly matched speakers, all in a robust and very portable package.

Or if you insist on ACUS, use just them, leave the Echolette at home.

Serious, I am sick of recommending same thing to Musicians, they say "yea ... sure ..." ... and a week later phone asking ... "can you recone old xxx speakers? ... I was not playing loud, I swear, and they suddenly stopped working ... "

[Ekko]

I don't see any problems, just make sure the jack is insulated from the chassis.
Is this a kit that already includes the internal speaker?
Otherwise you could use an 8 ohm internal and run another 8 ohm external in parallel. Then it would be 200W alone and 400W with ext.speaker.

The Acus is a pre-made combo amp where the combined impedance of woofer and tweeter is 4 ohms. Just wondering -- would the woofer be 4 ohms with the tweeter being of negligible impedance? If so, replacing the 4 ohm woofer with an 8 ohm would seem to open up the possiblity you suggest (200W alone and 400W with external in series). However, in replacing the 4 ohm with an 8 ohm, and leaving the tweeter as is, would this alter the balance between the highs and lows in the Acus?

[glebert]

Is there a crossover network in this amp or is the tweeter a high impedance piezo type? I think if there is a crossover and you change the woofer impedance you will change the crossover network response and therefore the high/low balance.

[olddawg]

Just don't put a 2 ohm load on that amp unless it's rated for it. Otherwise you will have a toasters..

[g1]

The tweeter is listed as a 'compression tweeter' type, and with the price of the unit, I believe it would be a quality component (probably B&C as the amp is Italian). So as glebert suggested, changing the woofer impedance will alter the crossover frequency.
Aside from that, pay close heed to what JM Fahey said. If you want to use those echolette speakers, it is not likely they will survive, there is way too much room for error, even if only by accident.

[glebert]

With an acoustic baritone guitar and this much power and external speakers I would be seriously worried about feedback.

[pdf64]

A crossover will be designed for a low source impedance. Connecting another speaker in series will create an effective high source impedance, and one whose impedance varies significantly with frequency.
Point is that it will really mess with the response of the combo's speaker system.
But that's not to say it won't sound fine.

[Ekko]

Thanks very much for all your replies -- I will digest and cogitate!