The principal elements of my set up are shown below.
Tascam CD01 u CD player
Crown SL2 preamp ( bought from Subwoof )
JBL M553 crossover ( ebay from Grass Valley in CA. )
Rotel RMB 1066 power amp. 6 x 65w ( only )
Once this is all in place and running other bits and bobs will get patched in.
Well the big day came at last, but first let me lay out a few aspects of the set up that are of influence.
The Crown Pre is really good and quiet too but it does have a high overall output. The power amp has tweakers on the inputs but I still feel that the o/p of the pre could use some padding.
The crossover is more or less made for this job with a few proviso's.
First the upper crossover frequency as standard does not accommodate the 2405. This can be altered and there is discussion of this here http://www.audioheritage.org/vbullet...highlight=m553 The other shortcoming is that it does not carry delay for time alignment. On the positive side there is pre-emphasis onboard to equalise for 2380 series horns. The x/o ferquencies are easily dialed in and the controls are logicl and easy to use. Nice XLR connectors all over the back panel. Where the cables become RCA Phono I have unbalanced the connection at the phono end.
The Rotel Power amp is pretty neat for this application. I had its predecessor in use in the family pub running 2x B380 4x control 1 via a Bx63. Both of these allow you to bridge any pair of amps so in that mode you get 1 x 130w and 4 x 65w. Well I can tell you we had some raucus nights with no problems at all.
In my new set up the rmb 1066 is in 6 channel mode, ie each driver gets its own 65w amp section. Now for some of you American chaps this may not seem much but remember that there is no insertion loss here so straight off the bat that little 65 is worth a good deal more. Second because each amp section is only handling a limited bandwidth, then it has a much easier time of things.
So how did it go ? -----------------
Well , I have only rigged up one so far just to prove the system. I have no passive components downstream from the amp so it was hooked up and tentatively each amp/driver section was run up to a working volume and then backed off to a trickle. Bit by bit I dialled in a presentable sound and listened for a while to my favourite Calum Kennedy track ' Dark Lochnagar ' (http://www.youtube.com/watch?v=2Swqe...eature=related)
Now at this stage remember a few things. Preamp is running in MONO ( yuk )
the drivers are cold , the woofs have not been run since I refoamed them , the compression driver is brand new and needs run in and I do not as yet have a scooby what is what with respect to phase. I think the woofs are red = forward as are the comps but the slots are red = backwards. so it should be
woof -- in phase mid -- reverse slot --reverse.
Just for simplicity I started with everything +++ so my first change was to flip the mid. This gave a positive improvement but along the way I have been tweaking the x/o frequencies a little also.
Now bear in mind I have no measurement tools other than my ears.
Conclusion-- As the system warmed up and as things got dialled in I am pleased to tell you that thus far I am delighted. The woof is sounding great with no boom just tight and extended with the authority that is the trademark of JBL. The horn is not squawky and is really not beamy either. I had a bit of a time messing with the levels and x/o between the horn and the slot and to be honest I think I have to flip the slot. I will try this when the other speaker is rigged up.
Anyway I found a new way to get to the pub..... a little reggae music and this will blow me right out the window and down the street. Compared to my 4315's there is so much more ready gain or headroom. wow dB max who cares its way more than I could ever use and I do have neighbours.
I think I am nearly in the zone. Just have to build some grilles.
Last edited by macaroonie; 11-20-2007 at 08:26 AM. Reason: addenda
I know that some of you have trodden this path many times before, and lets face it all I have done so far is to build a working box for the woofer.
I would welcome any input or constructive criticism regarding the technical aspects. I know that most folks advocate the use of protection caps on the MF and HF. I can see why but this amp is brim full of fast o/p protection and I feel I can pass on that subject unless a convincing case can be made.
Should there be any other response shaping in there.
The B&C driver is as near as dammit a copy response wise of a 2445 and was picked out for that reason.
Does anyone have the phase thing down.?
etc etc
Otherwise
What a great thread you have constructed........and great cabinets as well. This is an outstanding documented process to get cabinet maker quality without a substantial investment in cabinet making tools. Well done.
Thank you.
Indy
The "zone" has no boundaries, Macaroonie. Your speakers look like a project well worth the time investment. Interested in your impression of the horn/woofer integration over time. Always the concern to me in matching such drivers.Originally Posted by macaroonie
DavidF
David F
San Jose
Or at least this thread. I have had work and leisure commitments and have been cogitating on how to proceed with the finishing details of this build.
If you have followed this through you will be aware that the system is to run active. Asa consequence ther are 6 conductors going in to the cabinet.
There are several ways to do this, 3 normal speaker wires ( untidy in my opinion ) or a 6 way cable. As I mentioned before I sourced this nice OFC 6 way speaker cable from VDC in England. The next question was how to connect to the speaker cabinet itself.
Again choices. I could direct wire onto the drivers or use conventional binding posts or sockets .In the end for neatness I decided to use an Amphenol EP series connector with 6 pins. This has the advantage that there is no way that a cable can work loose and potentially short and also it is a one shot deal to disconnect. The contact performance of these is excellent also.
My front end components are going to be sited in an alcove some way away from where the power amp will be hidden ( in an old blanket chest or as we call it a kist ). The JBL M553 x/over provides 3 outputs per channel ie. Bass Mid and Treble. For the same reasons as with the speaker cable I found an 8 way professional multicore from VDC. They do not do a 6 way so I will discard 2. This cable has to go down through a cable chase and then under the floor to the other side of the room. You can see the size of it in the pics. The individual screened conductors are quite fine but that will not be an issue in balanced mode.
Well here we are at the end zone. I have spent a while staring at the boxes with no grilles attempting to get a visual take on what would be right.
The proportions are quite different to the L300 being a bit narrower and about 4" taller. I had the feeling that a plain flat front would look too 'big' yet there is no obvious spot to make a natural split for a two part grille.
Here are pics of my solution thus far. The plan is to rout a slot across the cross bar and use a black cable or somesuch to jam the Zilchcloth into the slot as I cover the grille.
I'm about to tackle the corners. I queried with Mike Bottz as to his methods for this tricky little task. The thread is here somewhere.
More when they are done.
You may have noticed that these are not built in the same way as the originals. The first point is I do not have to accommodate the acoustic lens so the frame can be shallower front to back. However I wanted to keep some of the flavour of the original hence the depth they are (47mm ) rather than 75mm. I have taken some care to round off the internal edges to soften any sonic effects. This has the added benefit of giving the cloth a soft edge to pass over so there should not be any visible crease like you see sometimes.
You can see in the pics above where I have had to rebate the frame to accept the edge of the horn.
These are only glued and clamped, no screws.
I have had a little problem with warping but as the wood gets used to the indoor atmosphere all should be well.
This pic is the first of the corner rounding and the peg fillets. I have done the rounding by marking up directly from the cabinet at the back and by using one of our £2 coins at the front. I then used a sanding disc in my grinder to approach my marks and then finished off by hand using 120 paper over a block of wood. They look pretty good with the Z cloth stretched over.
I still have a lot of tidying up to do but am moving in the right direction.
These are tricky wee guys to get right
Well I finally got some time to fiddle with the grilles. These have been tricky and a lot of work but I bit the bullet and got tore in as they say. The awkward bit seemed to be the horizontal slot but actually that all went pretty easy. Pics are self explanatory. I gave all the sharp edges a gentle sand off by hand just to give the cloth a less sharp edge.
As always the Digital image has trouble with that blue cloth. Its overcast today so I will wait till the sun comes out and will whip one speaker outside for a good pic
The darker blotch is just a damp patch that got mucky don't worry
tidy work Mac
Rich
As you well know this is what is called proto typing. It takes time thought and application. One wrong step and its over. Hey I know where the Boo Boo's are but I'm not telling.
I got the Zilch cloth adhesive thing down though if anyone is interested.
Hi Mac
Nice work!
I too, like the new avatar...
Cheers from across the pond
Mark
Absolutely gorgeous! Let's hear about installation of the zilch cloth please!
Russellc
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