FE108E BLH question

[rockthebox]

Hi folks,

I've decided to take the plunge and build the Fostex BLH with FE108E sigma's.. all the talk on this forum convinced me it was the way to go.

The plan at the moment is to couple them with a REL R205 sub as I've read that the bass performance although very accurate, doesn't go massively low and I want to fill out the bottom end.

I'm planning on driving the FE108's from a pair of Hypex class D power amps.

What I am considering is putting a High Pass active filter in front of the power amps to take the low frequency elements that the REL will be handling away from the horns.

My questions are:

1) Is this a good idea? Will this help the Fostex driver and give better sound quality?

2) If so, what is the recommended cut off frequence and order of the filter.

I'm currently thinking about putting a 2nd order HP LR filter at 80Hz.

Thanks in advance for your help. I can't wait to get them built. Will keep you updated if people are interested.

Cheers,

[Andrewbee]

Is this a good idea? Will this help the Fostex driver and give better sound quality?

In theory yes, but in reality "maybe". In my experience the will be a definate loss of cohesion when filtering the fullrange and adding a sub. I personally have never had a seamless transition but ymmv.

If so, what is the recommended cut off frequence and order of the filter.

You need to experiment, I would suggest cutting off @ 80 - 90hz @ ~24db/ as a start.

If you need bass, the Nagaoka Swan will do it for you with the same driver.

Sorry that I could not be more helpful.

Andrew

[chrisb]

Originally posted by rockthebox
Hi folks,

I've decided to take the plunge and build the Fostex BLH with FE108E sigma's.. all the talk on this forum convinced me it was the way to go.

The plan at the moment is to couple them with a REL R205 sub as I've read that the bass performance although very accurate, doesn't go massively low and I want to fill out the bottom end.

I'm planning on driving the FE108's from a pair of Hypex class D power amps.

What I am considering is putting a High Pass active filter in front of the power amps to take the low frequency elements that the REL will be handling away from the horns.

My questions are:

1) Is this a good idea? Will this help the Fostex driver and give better sound quality?

2) If so, what is the recommended cut off frequence and order of the filter.

I'm currently thinking about putting a 2nd order HP LR filter at 80Hz.

Thanks in advance for your help. I can't wait to get them built. Will keep you updated if people are interested.

Cheers,

I can't speak to the questions regarding most suitable XO frequency and slopes for your particular application (regardless of others pet favorite formulas, experimentation in your system will provide the answers) .

However, I can attest that having heard the driver in question in quite a few enclosure designs, Fostex and otherwise, by far the best sounding was Scott Lindgren's Aiko (originally intended for a Lyeco 4", but for me the Fostex kicked it to the curb)

http://homepage.mac.com/tlinespeaker...map-010407.pdf

[rockthebox]

Hi guys,

Many thanks for your replies.

I'll take your advice and start with an Xover 80-90 Hz 24db/oct and experiment from there.

I already have a REL sub, so will try that for a start as well and see how well I can get it integrated.

Thanks also for passing on the Scott Lindgren design. That does look like a nice design. I'm wondering just how much better it is than the Fostex plan? What was your impression of how different the speaker sounded?

Cheers,

jason

[rockthebox]

Another quick question if that's OK..

I've ordered the Fostex drives and they should be with me soon. Is it OK to break in the drivers with program material before they are put in the cabinets, or should they really be broken in when in the boxes?

I know I'm going to be mad keen to listen to them and start the fine tuning when the boxes are finishes. So it would be good to start the break in period now. However is having the real loading an important part of break in?

Cheers,

jason

[Scottmoose]

Better done out of the final cabinet, or you'll spend the best part of a year or more getting the suspension loosened up (horns & their subsets tend to control driver excursion better than other types of enclosure).

Re cabinets -I'm not a fan of the Fostex box; it isn't really one of their best & has some cuppy colourations across the midband. Chris & DaveP10 have a lot of experience with the 108, so I suggest you be guided by them WRT cabinets for it.

[rockthebox]

Thanks for the info..

I've been studying the Scott Lindgren plans and have a cutting plan which I'm going to take to the local timber supplier to get a quote for supply of the wood cut to size. (will go for 15mm birch ply)

I think it's actually going to be easier to construct than the Fostex one as it's all right angles.

I'll keep the group updated with posts and pictures.

Cheers,

jason

[Scottmoose]

It should be an easy enough build -I designed it, & the larger cabinets in the range, with that in mind. Complex angles can be off-putting to a lot of people, especially if they're not over-confident in their woodworking, so this style of design tends to encourage them to have a go.

[rockthebox]

I'm definately feeling like giving it a go :-)

Thanks for sharing your design. It looks great.

jason

[Jamesuk1]

Hi,I for one can vouch for scotts Designs.I built my Chilli Changs a few weeks back and to be honest i cant stop listening to them.They have a very involving sound that draws you in to the music.I used to read while listening to my music.
Not anymore !!!