Moi OB speakers

Just for fun! Have a look at the last post in this thread - http://www.diyaudio.com/forums/showthread.php?s=&postid=940403#post940403

 

Very nice Simon.
You have been busy!

 

That Magnum is beautiful looking driver.

It seems dipoles sound best with treatments too, who'd have thought that

 

Hi,

Looks like you are having fun.... Toldcha the EM Mag is not at all bad for the job.

Ciao T

 

Yup! I was planning to try the Supravox as well just so I know I have got the best, but I really feel no need. Vocals are soul touching. If the Supravox is better in this respect, it can't be by much and it has considerably worse low end SPL ability.

T (or anyone), do you have any experience in how much difference removing the dust cap makes to HF performance? It is my plan to mount a tweeter in the pole piece but I don't want to upset the woofers dispersion or something.

 

Hi,

This depends on many factors.

First, all this applies only to solid, airtight, dustcaps....

If the Dustcap is the same diameter as the Voice Coil removing it may reduce the extension towards higher frequencies. On the other hand, if the voice coil is smaller in diameter than the dustcap removing it may improve the HF or actually reveal a large nasty breakup resonance.

Given the fairly sane cost of a Magnum 12 and the even more reasonable exchange/repair cost, the best way is to try it.....

Ciao T

 

What about placing a thin but rigid mesh across the driver and mounting a small tweeter on it (behind it). You'll get reflections but it might be an acceptable compromise if your preferred method doesn't work. Just thinking aloud.......never tried any of this.

 

Hi,

The approach MEG takes works fine:



Past that, simply cover the tweeters back with Felt, this deals with a lot of the problems.

Ciao T

 

I would prefer a proper coaxial mount though as the gap behind the tweeter can cause resonance and increase linear decay. Further, the wave-front is not concentric if you are off-axis.

I will have to try it, as you suggest. If I am careful I could always put the dustcap back on!

The other thing that makes me unsure of just mounting the tweeter like the MEG, is that for a 1.2KHz Xover I think the tweeter would need a baffle of some kind (or speaker cone behind it).

 

Simon, where do you find the time? I was reading up on that Manger driver (not that I am an expert or anything) and it is very interesting. Most reviews mention the lack of a crossover point in the vital vocal / midband area which apparently helps - expensive though are they not? still thinking about going dit btw...

Steve

 

http://www.manger-audio.co.uk/manger-speakers.htm

That MSM C1 Active monitor looks interesting, though if you need to ask the price...

 

You just like it 'cos it has a grill

A concern with the Manger is that its off-axis response @1m is pretty lumpy. It smoothes out when you get a bit of distance from it though. I think this is because it produces sound in 'rings' from the driver.

 

1 metre is pretty close though wouldn't you say? and I prefer "naked" speakers.....

 

1m is close but most tweeters have a smoother response even from that distance.

sorry, getting you muddled up with Andy who was after some actives with a grill! Naked is definitely better!

 

So what do you think of dipole bass then Simon?

This is a route I am interested in investigating in the near future. I was looking particularly at the PHY-HP KM30 as a potential driver. It's a 12" with decent bass response but is reputed to be clean well up into the treble and is used full range. The coaxial piezo tweeter comes in at 10 kHz. I haven't heard one yet though.

 

TB - Markus Sauer lived with PHY drivers in OB mounts for years, so you might want to ask him about them. Sounds an interesting proposition - and a complete change from your Dyns!

 

I heard good things about the PHY drivers but I have also heard that they are very overpriced for what they sound like. They would also probably fall apart a bit when you throw on the heavy rock. Most full range speakers I have heard do.

In your position I would recommend having a look at the Supravox 285GMF, available from Real-Hi-Fi in the UK. They play nice and high (10KHz) but I would use them with a tweeter crossing over at about 2KHz because the off-axis response falls off then. You can order an open baffle version with extra excursion and a Qt designed for OB.

What do I think of OB bass? Well, for starters it doesn't go as low! But, because the woofer is big I can still hear/feel something right down to about 25Hz even though it rolls-off at about 40Hz. It interacts less with the room which is a very good start. It is also faster because of this. However, if the midrange is OB as well, then this interacts more. You NEED some form of treatments to get the midrange performance where it should be IMO. At least in the two rooms I tried. One large and long, the other my normal small listening room.

 

Cant wait to here the results!

 

Well you will have to

I have no speakers at all ATM. Just some woofers in baffles. Manger drivers on the way, as are the second pair of woofers.

You can hear them once they are fully completed!