Biamping the Revel f208

[Deleted member 20765]

Forgive me if this question has been discussed previously.

I am considering biamping my Revel f208 speakers. I'd like to know which drivers are accessed by the upper pair of binding posts and which are accessed by the lower pair.

Revel warns against using an external active crossover. Is this because the crossovers for the top and bottom binding post pairs are disconnected inside the enclosure when the straps are removed? So all I need to do is connect each amp to its own pair of binding posts?

The owners manual is not at all clear at all on this topic.

 

[Svend P]

Biamping does not yield any benefits

Bi-amping 101

This article provides a quick look at how bi-amplification works. The conventional scheme is to split the signal into two frequency bands before the power amplifiers that drive the speakers. The bass (LF) amp sees only LF signals and drives only the LF driver (woofer). The treble (HF) amp sees...

www.audiosciencereview.com

 

[Drengur]

Biamping does not yield any benefits

Bi-amping 101

This article provides a quick look at how bi-amplification works. The conventional scheme is to split the signal into two frequency bands before the power amplifiers that drive the speakers. The bass (LF) amp sees only LF signals and drives only the LF driver (woofer). The treble (HF) amp sees...

www.audiosciencereview.com

This discussion is very interesting and a must read for everyone who (like me) intuitively assumed you would get "double the power".

 

[JeremyFife]

Assumption: Revel say not to use an external active crossover because the internal passive crossover is still in place (not bypassed) i.e. it's pointless to bi-amp.

Just an assumption though, happy for someone who knows to clarify.

 

[Deleted member 20765]

Assumption: Revel say not to use an external active crossover because the internal passive crossover is still in place (not bypassed) i.e. it's pointless to bi-amp.

Just an assumption though, happy for someone who knows to clarify.

That's what I thought. And I agree biampling is not the way to go.
But we really still don't know about the internal design.

 

[Deleted member 20765]

Biamping does not yield any benefits

Bi-amping 101

This article provides a quick look at how bi-amplification works. The conventional scheme is to split the signal into two frequency bands before the power amplifiers that drive the speakers. The bass (LF) amp sees only LF signals and drives only the LF driver (woofer). The treble (HF) amp sees...

www.audiosciencereview.com

Yes, understood. I'd like to know what the internal wiring in the f208 is. If the xovers inside are bypassed then active biamping can work. If they are not, then biamping has no benefit.

 

[kyuu]

Yes, understood. I'd like to know what the internal wiring in the f208 is. If the xovers inside are bypassed then active biamping can work. If they are not, then biamping has no benefit.

I've never heard of a passive speaker where disconnecting the shorting bar between binding posts defeats or bypasses the passive crossover. If one did exist, that would have to be well documented in its manual as it would be highly unusual. The sole purpose of the two sets of binding posts is for biwiring/biamping, not for enabling external crossovers. If you want to do an external active crossover, you're going to have to open up the speaker and remove the passive crossover.

 

[Sokel]

Yes, understood. I'd like to know what the internal wiring in the f208 is. If the xovers inside are bypassed then active biamping can work. If they are not, then biamping has no benefit.

There's absolutely not way that the internal x-overs are bypassed when removing the bars.
That would be dangerous for the drivers.

What happens when you remove them is just that ways are separated, each with own x-over.
That's global, to all the passive speakers around (I hope)

 

[Deleted member 20765]

There's absolutely not way that the internal x-overs are bypassed when removing the bars.
That would be dangerous for the drivers.

What happens when you remove them is just that ways are separated, each with own x-over.
That's global, to all the passive speakers around (I hope)

So I thought. Bummer. But this does save me from buying another ML No 27!
Thanks everyone!

 

[Blumlein 88]

Internal crossovers on the F208 are not bypassed if you remove the shorting straps. So active biamping won't work as you hope it would.

There really is no benefit anyway. I wish they hadn't even made the binding posts that way on those speakers as I have a pair.

 

[MarkS]

Yes, engineering-driven makers like Revel and KEF that nevertheless waste money by putting double binding posts on their speakers are extremely annoying. Really downgrades them in my mind as possible purchases.

 

[kemmler3D]

What happens when you remove them is just that ways are separated, each with own x-over.

Wait, so they really put a full crossover on both inputs? I just assumed they connected everything to one crossover...

 

[kyuu]

Yes, engineering-driven makers like Revel and KEF that nevertheless waste money by putting double binding posts on their speakers are extremely annoying. Really downgrades them in my mind as possible purchases.

It's a business necessity unless they want to forgo sales from audiophiles who expect that feature. The additional cost is negligible compared to the potential lost sales.

 

[thewas]

It's a business necessity unless they want to forgo sales from audiophiles who expect that feature. The additional cost is negligible compared to the potential lost sales.

Also theoretically in some cases there can be few (but most probably inaudible) advantages as written in the analysis of the in #2 post linked article.

One nice thing though which can be very audible is though is if you want to reduce the level of the tweeter without opening the enclosure and losing any warranty, like I did here.

 

[DVDdoug]

Wait, so they really put a full crossover on both inputs? I just assumed they connected everything to one crossover...

The full crossover consists of a high-pass filter for the tweeter and a low-pass filter for the woofer. The don't have to be connected together except at the inputs to the filters. Apparently, with this speaker they are connected together externally.

An external active crossover could conflict with the internal crossover both in frequency filtering and with phase shifts.

 

[kemmler3D]

The full crossover consists of a high-pass filter for the tweeter and a low-pass filter for the woofer. The don't have to be connected together except at the inputs to the filters.

That's enough to create a crossover in general, but are we sure this speaker is that simple? I've never built one but I know crossovers can involve many separate filters in addition (e.g. notch for tweeter breakup) and so it could be very expensive to include two copies of the whole crossover for a dubious benefit.

Apparently, with this speaker they are connected together externally.

If this is true, then disconnecting the bridge on the terminals would kill output from one of the drivers... is that the case here? (or on any commercially available speaker?)

An external active crossover could conflict with the internal crossover both in frequency filtering and with phase shifts.

Yes, the best you can do is full redundancy with the internal one, I think.

 

[Count Arthur]

When you have linking bars, or jumpers, the crossover will be separate internally:

This is a 2 way, but you get the idea.

Remove the jumpers, then connect your amp to just the lower speaker connectors. You should find that not all the drivers are working. Given that the f208 is a three way, with only 2 sets of connectors, I'm not sure how they've split it, lower connectors for the 2 woofers with the tweeter and the mid connected to the upper, or maybe the mid and the 2 woofers, with the tweeter separate.