Crossovers

Now I know that crossovers are designed specifically for the speakers and drivers they are in - but I couldn't help but wonder before refurbing my Beovox Penta crossoves what a difference a different crossover would make. My theory being that the Pentas have pretty hefty crossovers that need to be driven hard to make the speakers sound good.

So I have connected in a Monacor three way crossover - the difference in the sound is completely amazing, very very clear and that's only with two midrange units kicked in - bass is just as good and the treble smooth. The difference is so marked that I am wondering if the originals would ever have sounded this good - They appear to be like new with no parts damaged or worn or anything.

I will of course keep the originals so that they can be refurbed at some point and the speakers remain original but I am wondering if anyone else has experimented or customised speakers? I realise that the sound of the speaker is subjective and what sounds good to one person may sound rubbish to someone else.

I can only describe the sound as clear as my S60's but with much better bass extension and clarity.

Interesting experiment. But did you already install fresh capacitors in the old crossovers, did you recap the penta amps and redo adjustments? Because that should make them sound exactly as new.

A random monacor 3 way crossover will never give the sound B&O intended. And I like to think with the time and recources B&O invest in measuring and perfecting their loudspeakers they gave a fair amount of thought to the crossover design. If a simple crossover were just as good they would have installed one, as it would have saved them lots of cost.

But, if you like the sound, why not? They are your speakers after all. Maybe recap one penta and compare, I wonder what you'll find...

Martin (= die_Bogener) has done some work on the Penta crossovers in the past and is quite an expert. I've listened to his speakers and the result is phenomenal! So yes, apparently a lot of improvement is possible by modifying the Penta crossovers.

Cheers,

Kai

Hi, no i didnt do any work on the crossovers as i was sceptical that changing caps could have such an impact, however now eager to here what martin has done and any other thoughts and of course see how they sound with recapped crossovers

Martin has posted a workshop somewhere in the old forum. Must look it up whether it's still available. He doesn't just change capacitors. There were some other modifications, too. Dillen (another Martin) is also quite experienced on the matter. I was just trying to say that there is improvement possible in the crossover section - something that you have experienced as well.

Greetings,

Kai

This is a typical example of tinkering without any knowledge about crossovers and how they are depending many parameters.

For a start, have you thought about the crossover frequencies? Ever thought about the fact that different impedances of the attached speaker(s) might infuence the crossover frequency?

Have you noticed the difference of height at the outer 2 mids compared to the inner 2 ones. And why these 2 outer mids have an extra "filter" compared with the inner ones?

As you already stated, this your personal opion, which is fine. But don't encourage people to do the same. It's wrong. And that's my opnion and the correct one.

Die Bogener started doing well, but in my opinion failed to do it fully 100% properly.

I would suggest, take the original boards, recap them and make sure that your mids have good surrounds (not sloppy already perishing ones).

It has taken me a while to reply to this as I was quite cross at the last reply

A) yes I do understand about crossovers and am not without knowledge, I worked at the BBC as an engineer, the point about the midranges and different frequencies is valid but, imho irrelevant as it was over engineered

B) if people tinker and get too results then that can only be a good thing, if they are happy with it? Everybody hears things differently, rooms are different and the music we listen to is different.

C) really really dumb to state " I am right " no you are not, that is your opinion and You are entitled to it just as am entitled to mine. I think you totally misunderstood what I was trying to say. You cannot blindly believe that engineers 30'years ago were simply right when the materials they had to work with at the time were inferior to those we have now. Yes of course a lot of though when in and no one disputes that, but imagine what Jeff could do with a pair of Pentas now? Do you really think he wouldn't be tempted to tinker?

D) I was only trying to encourage debate, the simple,fact is that the speakers sound much better now than they ever did , I have had them for 20 years so I should know! It is a fact that the technology has moved on since they were designed and so have the components, however the basic design and drivers are amazing and they are superb, but it does not mean that modern technologies can't make them better and that we have to live in the past. If technology of the past was so great then why are we having to recap amplifiers and crossovers. Why can't we embrace the design of the past by encompassing modern technology.

Sorry, but I got really cross reading the reply when the assumption was that I knew nothing about what I was talking about! Each to their own I guess, and yes I would encourage people to tinker and get the best out of their equipment if that's what they want, times move on.

I'm having a strange feeling of déjà moo...

The most expensive loudspeakers often have the most complicated and expensive crossovers. It's all in the crossovers! That is why active speakers make sense. The amplifiers + active crossover probably cost nearly the same a high end crossover. 

Did you try restoring the original crossovers or are you merely comparing
a new crossover filter with fresh capacitors to the original with 30 year old ones?

Modern components are fresh but 1uF is still 1uF, 30 years didn't change that and neither Ohms law
nor any other electronic or mechanical calculation has changed either.

What may sound good to you may look awful on paper and sound weird to others.
(There's nothing wrong with that - I like to use Loudness myself).
But we really cannot discuss what sounds good or bad to you.
Give them a sweep and let's see their frequency response with original unrestored, original restored and
your replacement filters.
Then we'll know what you are experiencing and listening to.

Martin

If you like the end result, then that is right for you. There is an interesting article in this month's Hi-Fi News by Tim Jarman where he comments on the trend to tuning the sound a system makes to the sound that the user likes. He rightly states that this is up to the user but that such a set up will mean that the usual music listened to may be just to one's liking but that different music may not suit such modification of the frequency response (as that is what is being done) and will remain unplayed.

In my view, I rather have a system which replicates sound as accurately as possible with the ability to modify the sound by using loudness or tone controls if desired. But I would hesitate before saying I am right and another point of view is incorrect - it is only correct for me.

Peter:

If you like the end result, then that is right for you. There is an interesting article in this month's Hi-Fi News by Tim Jarman where he comments on the trend to tuning the sound a system makes to the sound that the user likes. He rightly states that this is up to the user but that such a set up will mean that the usual music listened to may be just to one's liking but that different music may not suit such modification of the frequency response (as that is what is being done) and will remain unplayed.

In my view, I rather have a system which replicates sound as accurately as possible with the ability to modify the sound by using loudness or tone controls if desired. But I would hesitate before saying I am right and another point of view is incorrect - it is only correct for me.

Well, I agree with your last statement Peter in particular. The first part is right line in the Do It Yourself Speaker Builder's Guide, no matter how bad your speaker is somewhere out there is music that makes it sound good, so a bad design is your excuse to go buy a lot of new music! This used to be called the Tower Records Rule, back when there were a lot of Tower Record stores.

Of course, instead of mucking with crossovers and such, making your system have a non adjustable tone control so to speak, better to use an actual equalizer, that way you can turn it back if you decide you preferred flatter sounding. I knew a designer once, he made two speakers, one top of the line for an older speaker line to replace a 70's classic with a more up to date incarnation of same, and his own high end speaker for his line (he had been bought by the company that now owned both his firm and the classic speaker firm). Big difference in design, the updated old speaker sounded very good in its own right, albeit suffering from the sins of omission you might expect, it was however warm, pleasant, and nice. His much more expensive high end job, was shall we say less accommodating to bad recordings. He said the one speaker was designed to make all your records sound better, and the high end speaker was designed to make them all sound worse. But more accurate.

But it's amazing, twice in rapid succession we've had people come on, post something about redesigning their speakers, things that due to the things they say indicate they have absolutely not a single clue or bit of actual audio design experience, even as a hobbiest. Then when problems are pointed out, get huffy and defensive and come back with "well "I" know what I'm doing, I've done...." Well, if that was the case there's no way you would have made some of the extremely incorrect and just plain dumb comments about your "project."

Obviously not going to get anywhere with this one, however I will get the original crossovers restored and see how they sound, I will then be in a more informed position to comment. I am not saying what I have done is right, just that it made a huge difference and has shown me what the speakers are in fact capable of, unfortunately the only three pairs I have heard all to me sounded lacking in the midrange and two had had the mid ranges reformed, so it has to be that the crossovers fail, as has been more than covered.