Tweaking Sextets.

[bob orbell]

I feel you would have more response if you had have said hello first instead of just jumping in, . BOB

[damian]

Originally Posted by bob orbell

I feel you would have more response if you had have said hello first instead of just jumping in, . BOB

Sorry Bob, I should have, so 'Hello' to everyone.

[bob orbell]

And a very warm welcome Damian, no offence meant by the way, I am sure someone can help you with your request. BOB

[damian]

Originally Posted by bob orbell

And a very warm welcome Damian, no offence meant by the way, I am sure someone can help you with your request. BOB

Thanks Bob.

I was concerned resurrecting an old thread that there might be nobody there.

[Black Stuart]

Finally the weather here, northern Tarn cooled and found the time to work on the Sextet x/overs but Sod's Law turned up.

I only opened up and removed one x/over rationally thinking that the second would be a mirror image of the first but it wasn't - the wiring for the second was at least 6 inches shorter than the other. In fact I don't know how the factory managed to solder this x/over

I had intended to keep the Mk 4 wiring to see how the cap/resistor changes had 'affected' the sound but now I have to see if the FEP tubing supplier will sell me a relatively short length for the speakers and for the experimental speaker cables I plan to construct.

I've often wondered if one of the benefits of OBs is that the wiring isn't subjected to the sound vibrations created inside a box speaker. To that end, air cored, oversized FEP tubing with woven cotton sheathing should ameliorate this affect.

One poster asked if anyone had the Mk 4 schematic, I found that someone had emailed me this in the distant past. The arrogant Serb got it wrong and it is exactly as I described. If anyone wants it they can PM me and I will send it by email to them.

The wiring in the Mk 4 is very different from that described in old posts about the earlier models, why use **** wiring in earlier models? - the woofer is wired with 1.5mm and the mids and treble seem to be of a reasonable gauge. If air cored conductors are demonstrably superior to wrapped ones for i/cs then I can see no reason why the same shouldn't be true for internal speaker conductors.

So next week I shall contact the FEP supplier to see if they will sell me 50M ( I can't imagine they will sell less that that).

Maybe after that I will think about placing the x/overs immediately after the amp. I only need less than 2M from amp to speakers so not sure how effective this will be - laten we kijken.

[Black Stuart]

I was hoping to use the existing plastic 'plate' that Heybrook used for the passive x/over and speaker cable posts but then I really looked at the build and was amazed how badly it was done.

Many of the caps of different parts of the x/over are touching by that I mean that some of the cap legs are jammed into the bodies of other caps. If the length and breadth had been just 1cm more this problem would never have occurred. So now I will have to make boards that negate this unnecessary problem.

Question -(1) why fit the x/over in the section of a speaker cabinet that has the most vibrations aka the woofer section.

Question (2) why were x/overs ever placed inside the cabinet, why weren't they always placed outside, simple enough to make an add-on box using vibration damping material to fix it. The speaker wireing could easily have been connected by push fit methods - of course extra work = less profits and like sheep all commercial speaker makers followed suit.

I've often wondered if OB speakers sound better because the wiring is free to air.

[bob orbell]

1, ask the makers of the speaker
2, as 1
3, How about sealing your room and installing a large vacuum pump to get a vacuum more than 20 mm mercury, you will also need breathing apparatus.
Bob

[Black Stuart]

Bob,
my questions were totally rational but your answers weren't - why am I not surprised.

[bob orbell]

Stuart, I always find your posts interesting, to say the least, sorry I could not resist . Bob

[Black Stuart]

Someone called Damian joined the forum to ask a question about the Mk4 version of the x/over - I hadn't lost it just misplaced it.

This schematic was posted originally by 'Lord' in 2006:

Lining change - bass double wool in bass enclosure

Bass driver- fit cap and PVA

tweeter - R - 1 Ohm, cap 3.9uF
Mid - 2 x 60uF parallel + 1 x 4.7uF paralleled , .35 air cored inductor
Bass 1.45 ferrite cored inductor, 1 x cap 30uF, R 8Ohm 5 W

I thought I had a Mk 4 x/over but I don't - the tweeter cap(s) are 1 x 2.2uF and 1.2uF paralleled. That's quite a drop in value.

Any opinions on the drop in value for the tweeter cap?

The cap changes will be K73-16 apart from a rough foil Audyn 100uF for the mid. If I decide to drop the mid value to around 100uF I could use a combination of K73-16 caps - laten we eens kijken.