PMC MB2i SE - Bi-amp or Single amp
 

I have a pair of PMC MB2 SE on order.

I am trying to decide whether to use a single Bryston 28b3 on each speaker.
The 28b3 has dual binding posts, so one cable to the bass, and one cable
to the Mid/tweeters.

Or do a 7b3 on the bass and a 4B3 bridged on the midrange/tweeter.

I already have the 7b3's and 4b3 to do the bi-amp.

Has anyone tried bi-amping vs single.

single 28's with biwire.

Single Amp to Single Cable to binding posts on Speakers here.

Why don't you try the 7b3s first and hear if that's enough? Adding the 4b3 you will need an active crossover as well.

Well i am still waiting on the speakers, but good comments here.

I will try the 7b3's first.

And just for fun, i am going to run a splitter on my interconnects(no crossover) and try the 7b3's on the woofers and the 4b3's(in bridged mode) on the mids, with a jumper to the tweeters. Too bad i don't have a crossover to try.


BTW has anyone heard of any Board or electronic issues with the MB2 SE.

Just curious because i had a pair of Ib2i actives and had a number of issues
with the boards.

I also have a friend who has the Fact 12's and he had to send his speakers back for service due to electronic issues.

Just don't want that type of surprise again.

What taps off your amps will you be using when bi-amping?

Not sure if i understand your question.

The MB2's are 4 ohm. There is no selection on the bryston amps for 8 or 4 ohm.

I think you will find the MB2se are 8 ohm.

Folkman... Welcome to AA! :wave:

Interesting their site does say 8 ohm. But the IB2 SE and BB5 SE are 4 ohm.

Yes they are definitely 8 ohms.

I bought a new pair 2 months ago and was initially interested in either the IB2se or the MB2se. PMC themselves recommended the MB2se as they are an easier load for the amp.

the MB2S are 4ohm as well.

My bad, I was unaware your amps do not have the ability to select the different impedance levels manually to match the speakers connected to them.

From the PMC manual, impedance for MB2SE is 8 ohms.

This is what I was asking.

Single Amp > HF_MF_LF = Impedance of 8 Ohms
Bi-Amp 1st Amp > LF = Impedance of ?
Bi-Amp 2nd Amp > MF_HF = Impedance of ?

I don't know the answer, that is why I am asking. It seems to me that you would have different impedance ratings when all three drivers (HF_MF_LF) are connected vs. two drivers connected (HF_MF) and one driver (LF) individually connected.

I sent an inquiry to my dealer.

According to the PMC website, the current MB2S have an Impedance of 8 Ohms. :scratch2:

Please post the results when you get them.

Dealer said the impedance was the same.

Now I an no electronics engineer , but from reading I believe there is a change in impedance when splitting a crossover.

Apparently impedance specs are normally given with both high and low crossover networks and drivers connected together.

Usually when splitting the crossover , the mid/tweeter section will exhibit a higher impedance and the woofer section a lower impedance.

Hmm, guess i was wrong.

With this configuration, you will need an active crossover.

When doing some research on bi-amping, it was noted that using amps with different gains/sensitivity will unbalance the intended sound of the speaker and therefore an active crossover was necessary.

or

Use the same style amp for each of the feeds; Bass and Mids_Tweets.

This was interesting.

https://pmc-speakers.com/technology/crossovers

The bryston amps have a selectable gain switch, so they can be all set to the same gain, so it can be done without the crossover.

That is an interesting article, but they talk about the fact speaker crossover.
I assume(hope) the same care is taken for the MB2SE speakers also.

I had a pair of IB2i Actives and had to replace the boards 3 times.

PMC MB2i SE - Bi-amp or Single amp
 

Oh great, sounds like you are ready to go.



BTW - What color did you go for?

Amarone

Great choice.

Any updates?

:ttiwwp:

Just wanted to chime in. In my opinion, you should start by looking at what SPL levels you want to listen on, and then go for specific distortion levels. A single amplifier could well be good enough for your use. However, some people complain that the MB2 is bass-lean, which if you find is the case you could help by using a different sensitivity amplifier on the bass transducer; alternatively, you could use a +3 or +6 dB pad on the input to the bass power amp.

Also wanted to add: Either case, you have two options on how to split the signal - either use a passive crossover (i believe your MB2 comes with one, mine comes without), or an active crossover like the PMC 10B (for tri-amping) or Bryston 10B or 10B-sub (for bi-amping) and then bypass the passive crossover built into your speakers. The active crossover solution creates less IMD between the channels during amplification. This is because with an active XO, the LF amp only amplifies the LF, and the MF/HF amp only amplifies that, so there's less non-linearity. With a passive XO, the MF/HF amp also gets and amplifies the LF, and includes the distortion products of LF in its output shifted up to the MF/HF area; then the LF is cut out by the passive XO, but the distortion products remain.