Bi-Amping

[PeterJohnson1]

Hello all!

I've just acquired a Trace Elliot GP11 4x10 combo,and I'm thinking of combining it with my ancient HH rig ("Bass Baby" 150W head & 2x15 cab) to make a bi-amped rig.

So my questions are:-

1. I need a crossover. Will any of those 2 way stereo/3 way mono 24dB/Oct rack units that are all over Ebay be any good, or if not, can anyone recommend anything?

(I know I'll be going unbalanced/balanced/unbalanced, not a problem.)

2. What crossover frequency would you recommend? I read an article many years ago and I think they said 250Hz but it was loooong ago and I can't remember.

 

While I'm here, does anyone know what the wattage is on my combo? I think it's 150W but strangely can't find any specs on the web.

 

Thanks!

 

Pete.

[itu]

There are X-overs in pedal format, too, like Schalltechnik, KMA (Tyler), and Iron Ether (Divaricator). I think their use case is to put certain fx to a frequency limited loop.

 

Your rack units are functional in line level signals. I think you could find something smaller meant for car stereos. They may be cheap as chips, but powering can be slightly complicated (12 volts).

 

About the X-over frequency: the best way to find the right f is to do trials. I like 400 Hz with my fx board (chorus, flanger, fuzz...), but your amps may like something completely different.

[PeterJohnson1]

 

16 minutes ago, itu said:

Your rack units are functional in line level signals.

 

I plan on using either the preamp on the GP11 (out through the "send", or my old Behringer V-Amp Pro, through the x-over then highs back to the GP11 "return" and 4x10, and lows to the HH power amp & 2x15. So yes, I'll be using the x-over at line level.

I've had great results with the V-Amp & HH rig. Midi switching is amazing!

Edited February 7, 2023 by PeterJohnson1

[Bill Fitzmaurice]

Don't bi-amp when both speakers are operating in the same frequency range. Chances are your Trace 410 goes if not just as low then almost as low as a 215. You might want to separately power the 215, for independent volume and EQ control, but you wouldn't use a crossover. Where bi-amping would make sense is using a 110 with a 215, and then only if the 110 is loaded with a guitar driver.

[PeterJohnson1]

14 minutes ago, Bill Fitzmaurice said:

You might want to separately power the 215

That's what I'm planning to do. I think our posts crossed, see above.

 

[Bill Fitzmaurice]

I saw that, but separately powering isn't bi-amping. I said 'you may' as one amp may suffice, if the impedance load isn't too low,

[PeterJohnson1]

23 minutes ago, Bill Fitzmaurice said:

separately powering isn't bi-amping.

 I know. It's dual amping. The separate power amps are after the x-over, which IS bi-amping.

Bill, with genuine respect, your replies aren't making  a lot of sense to me

. Maybe I'm missing something, but...

"Don't bi-amp when both speakers are operating in the same frequency range. ......" Then why does the concept of bi-amping even exist?

"Where bi-amping would make sense is using a 110 with a 215, and then only if the 110 is loaded with a guitar driver."

I really don't get this. I'm sure the 4x10 cabs made byTrace Elliot, Hartke et al aren't loaded with guitar drivers (I'm not saying you can't use them, you'd just get a different frequency response).

Let me be clear on what I'm trying to achieve. I'm looking for as much clarity as I can get. I do a lot of chord work, which can get muddy at times. I know that using a x-over will not only separate high notes and low notes, but will also separate upper harmonics from low notes, which I'm hoping will cut down on intermodulation distortion and clean things up a bit. I've even considered a third frequency band and getting some HF horns.

Telling me "Don't bi-amp" is pointless. Why does anyone do it? Why do (did) amp manufacturers make preamps with x-overs built in? There has to be a point to all of that.

I have to find out for myself.

All I wanted to know was a recommended x-over frequency, and if I could use a line level PA X-over (available used and cheap).

 

[Bill Fitzmaurice]

45 minutes ago, PeterJohnson1 said:

"Don't bi-amp when both speakers are operating in the same frequency range. ......" Then why does the concept of bi-amping even exist?

When you have one speaker that's optimized for use in the lows and one that's optimized for use in the highs. Electric bass 410s and 215s are not. They're both full range.

[PeterJohnson1]

1 hour ago, Bill Fitzmaurice said:

When you have one speaker that's optimized for use in the lows and one that's optimized for use in the highs. Electric bass 410s and 215s are not. They're both full range.

Right, I get you now. Yes, you're absolutely right. All my speakers are full range. They do, however, have differing frequency responses and resonant peaks. The 4x10 defo sounds brighter. I'll be taking advantage of this.

Also, there's inertia. A 10" speaker finds it easier to vibrate at high frequencies than a 15". The 15 can do it, just not quite as well as the 10. So, it's a case of any little thing I can do to minimize mud.

And it'll be fun to try! I hope my explanation above of what I'm trying to achieve clarifies my intent.

[pbasspecial]

Might also be worth looking at getting something like the Boss GE7B so you can cut and boost certain frequencies which might be creating the said muddiness. 

[PeterJohnson1]

27 minutes ago, pbasspecial said:

Might also be worth looking at getting something like the Boss GE7B so you can cut and boost certain frequencies which might be creating the said muddiness. 

Yes, there's a 10 band EQ on my "new" combo I'll be playing with! (See pic in first post.)

[DGBass]

Regarding the wattage of your 4x10 combo, i'm aware of two versions of these early units. It looks like a Mk2 you have and i've seen ones with a PM2S output board( 2 x Hitachi Mosfets ) and a PM4S output board( 4 x Hitachi mosfets). The PM2S has a high voltage supply and gets about 150 watts at 4 ohms from the two mosfets however these were sold as 8 ohm combos so you'll be looking at approx 90-100 watts for the PM2S. Its a loud 100 watts though as the speakers seem very efficient. The extension speaker output jacks on the rear are also blanked off on this model as it was only intended to run at 8 ohms. I have one of the PM2S versions. The speakers in the PM2S version are Celestion TE C10-50L (50 watt) heavy magnet units. 

The PM4S version is around 150 watt as well and usually has at least one available extension speaker jack on the rear panel and can run at 4 ohms. The speakers are different on the PM4S version, I think slightly higher powered Celestions. The back panel is usually a giveawy as to what version you have.

[Downunderwonder]

I wouldn"t mind betting there are more lows available from the 410 than the 215.

 

A faux crossover with the EQ on the Trace would effectively turn it into a sub pretty damn well. Keep the low slider bottomed and probably the next up cut some as well. Boost the stuff up to 150hz and cut the rest hard. You'll hardly get a peep out of it, aside from the woof.

 

Do the opposite with the H/H and you might get a better sound than you think. 15's not labouring over bass and having potentially 150w of treble up them instead can really scream! I recommend taking it easy with the loud knob.

Edited February 7, 2023 by Downunderwonder

[Bill Fitzmaurice]

3 hours ago, Downunderwonder said:

I wouldn"t mind betting there are more lows available from the 410 than the 215.

It's certainly possible. How low or how high a driver will go isn't determined by its diameter.

[Phil Starr]

12 hours ago, PeterJohnson1 said:

Right, I get you now. Yes, you're absolutely right. All my speakers are full range. They do, however, have differing frequency responses and resonant peaks. The 4x10 defo sounds brighter. I'll be taking advantage of this.

Also, there's inertia. A 10" speaker finds it easier to vibrate at high frequencies than a 15". The 15 can do it, just not quite as well as the 10. So, it's a case of any little thing I can do to minimize mud.

And it'll be fun to try! I hope my explanation above of what I'm trying to achieve clarifies my intent.

 

I think that's the point isn't it. "fun to try"

 

I don't think you 'need' a crossover, at least not yet. The thing that matters is that you have two amps with different sounds and you can explore the effects of setting extreme eq's on one or both of them and then blend the sounds using the volume controls on each. Back in the day it was a recognised technique to 'bi-amp' with a bass amp for the lows and a guitar amp for the highs for bassists who could afford it. It wasn't very scientific but someone with a good ear could sometimes find an interesting tone.

 

Crossovers do something very different a 24db/octave crossover will effectively split the signal so one speaker only gets the highs and the other gets the lows only. Both your speakers will have plenty of low end and neither have any real highs unless they have tweeters. The extra brightness is probably coming from the midrange. The muddiness from a lack of midrange at some frequencies. Using a crossover doesn't make a lot of scientific sense with the amps you have as they probably have similar frequency ranges just with differing timbres. Save your money and experiment with what you have. It'll be fun to try

 

[BigRedX]

Does the Trace Elliot have a crossover built in?

 

The stand alone pre-amp version of GP11 did.