speakers

hi,
i'm wanting a bit of a change however money is tight so last sunday i decided to swap the resistors on my ipl's crossover. when you get the crossover kit you are given 3 resistors for each crossover. these are 5.6, 4.7 and 3.9 ohm values.
only 2 need to go on the xo as r1 and r2.
when they were built r1 = 5.6 and r2 = 4.7 for lower mid / treble output. i've now swapped them so that r1=4.7 and r2 = 3.9. treble output has increased slightly but i'd like a bit more would it be safe to lower the values further say r1 = 3.9 and r2 = 3.2 to keep the numerical sequence going or do i risk blowing stuff up mid is an audax hm130z12 and the tweeter is a morel mdt30s.

also as the mid is mounted with the back venting into the transmission line i was wondering if there was some way of enclosing the back of it (there is a bit of interaction between the mid and bass drivers) - i was thinking a piece of pipe with a flange that can go between the driver and the cabinet the screws holding the driver onto the cabinet would go through the flange and hold it steady - i's then stuff the tube with long hair wool. is this an idea born of lunacy or could it work. if so anyone know where i can get some pipe with a flange that will fit into a 116 mm hole?

overall i'm after a bit more of a forward mid / treble with minimal outlay and effort.

sorry if these questions seem basic or idiotic but i've not really got a clue and would like to know.
cheers


julian

 

transmission lines are very sensitve to throat alterations .....

I can't quite grasp your tube plans but this may adversly affect performance elswhere.

As to the resistors not certain without checking.

One of the quickest simplest ways to improve sound is to replace the wetstring with good cable ....not certain what you've fitted to them but this may help.

 

These resistors are in series with the tweeter and midrange drivers respectively? Yes, you could lower or remove both without risk of damaging the drivers. They are padding resistors to match driver sensitivities. However in doing so you will also lower the loudspeaker impedance making the loudspeakers more difficult (current hungry) to drive.

If the loudspeakers have a nominal 8-ohm rating then reducing the values of r1 and r2 by 30% should be fine. The worst that will happen is you will blow the output fuses on your amplifier (assuming such is fitted) when you crank it up.

 

yeah they are (they are the first components off the mid/trebble positive binding posts. i may try removing them altogether and see what happens - my amps are pretty sturdy things - the transformers proclaim themselves to be 5kva each so i'm not too worried about them giving up not sure if they have output fuses although their startup sequence doesn;t thump the loudspeakers so there is something relayish in the way there - you can hear 2 big clicks when they throw in sequence.

if that's too bright maplins do 1, 2.2 and 3.3 ohm resistors in 10w ceramics (which look like what i need) so i might pay them a visit this weekend and see what they have.

internal wiring is as recommended by ipl for the mid and bass (hu 1 - looks like simple qed stuff really) treble is some fine stranded silver coloured stuff - not sure what tony used but i'm sure it's decent quality.

may look into changing the internal wiring what would people suggest - i'm currently using chord odyssey 2 as speaker cables simply because of all the cables i had (odyssey, vann damme, qed cheapo) it sounds marginally better to my ears. i'd like to keep the wiring loom from amps to drivers the same but odyssey 2 is just too expensive at the moment (90+ quid on e-bay for 2x 5 meters) my budget is around 40 or 50 quid at a push for something that will knock my socks off - ideally i don;t want to go over 30. for safety's and mistakes sake i'd probably need about 3 meters per side internally and 2x2 meters per side externally (i bi wire as it sounds better to me). so 14 meters in all. any suggestions?

 

Chord Odyssey
19 strands 12 AWG Silver Plated Copper
Teflon (PTFE) insulation
About £17 per m

RS Stock no. 358-179
PTFE equipment wire
19 strands 12 AWG Silver Plated Copper
PTFE insulation
About £2.50 per m (£50+vat for 25m)

What’s the difference? About fifteen quid a meter.

IPL HU1 = RS Stock no. 365-896

Search this forum for "RS Pink"

 

Good choice........

or more exotic ......silver ribbon or straight 1mm dia solid core.


my personal taste would be for no silverplating on the copper but .....it looks good value for RS!

 

pete,
what sort of price is the silver stuff and where can i get it from? last time i looked at silver wire it was about 10quid a meter which blows my budget big style.

i've tried a couple of stranded copper wires but the odyssey worked better in the context of my system - i've also heard that there's a difference with solid copper any suggestions on where to go to try that too?

mosfet,
wow, thanks for that - hell of a saving there. it only seems available in a 25 meter roll though which is a bit more than i'd need (although more might come in useful later so i might just go for it)

cheers


julian.

 

twisted twins fron the tnt site and Mills resistors from hi-fi collective. Changing the caps will also have a decent effect, well I found that on my IPL S4

 

I can get 4n 1mm dia for about £2.50/m uninsulated or 25m of 0.5mm uninsulated for £35 plus postage ....

even if you twisted up three cores of 0.5 with a drill and sleeved in cotton tube the difference in clarity should be marked.

 

what did you think of these?

I've seen them and wondered.

 

I think they're okay, there's a worthwhile improvement other 'white coffins' and not badly priced.

 

Julian,

Try here

Rgds,

Lee