Reducing inductor value on woofer

[Manimal]

A few months back I took the plunge and built my first ever DIY speakers;

IPL M3TL mk3 Transmission Line

Whilst they are very smooth I've always thought that I'd like to be able to get more transparency from the little mid/bass.

I've changed the supplied inductor on the bass for one that is giving me more presence in the mid and a livelier overall presentation. This new sound seems to suit and I'll think I'll stick with it.

The old inductor has o.8mm wire (no idea of its inductance) and my new one has very thin wire (29AWG). Is this an issue or should I get the new inductor (1.06mH) in the same diameter wire. I'm new to this lark and wondered if there could be any power handling issues using a thinner diameter wire.

By the way love this site - great info.

[infinia]

I'd stick with the same wire gauge, going with much thinner will effect the resistance and increasing the effective Qtc on the driver. IMO wouldn't reduce the old inductance beyond 20% unless the original design has more issues. perhaps consider unwinding some turns on the old inductor . The web site claims "super power steel laminate inductors" so low resistance / loss is a concern more than power.

[Manimal]

Thanks for the reply - I'd taken about 5 turns off the old one already and the change was so subtle that I'd thought I'd just swap it out with a couple that I had lying around doing nothing and see what the outcome was.

I had wondered about the effect of changing the value of the 4.7ufd capacitor too. I may revert to the original inductor and then change the capacitor to see what effect this has before finally settling on an inductor value.

[infinia]

yeah for the midrange changes around the crosspoint esp offaxis i would choose to play around with the shunt cap moreso not to impact the bass shelving.
better advice knowing what exactly the crossover / driver specs are and images don't hurt none.

[Manimal]

I'd mistakenly thought I was using a 1.06hm inductor but its a 2.2mh instead so I'm probably within your 20% guide that you mentioned earlier. Lots more life and impact but less weight to the sound.
May be a little fatiguing over time so will definately play around with the capacitor. I've got a few kicking about so its good cheap fun & I'll hopefully learn something too...

The info I have on the crossover is that its crossover point is 4000hz and 2nd order. (If I'm honest I'm not too sure what 2nd order means).
Driver specs were not supplied with the kit just the drivers themselves. Fountek Cd1.0 and a HiVi 5 inch magnesium driver.
I did a few pictures when i built them - here's one of the crossover.


Just dug out a picture of the finished speakers -

[infinia]

hey thanks for helpful information and posting the pictures too.
the electrical order is relating to the number of reactive elements in the filter. I see the low pass filter on the woofer shown there has a series inductor and shunt cap so it's a 2nd order like you mentioned. Also the largish inductor value indicates there is quite a bit baffle loss or bass shelving ie designed for free standing bass. Large baffles or close by floors and walls tend to reinforce the bass , perceived by some as loss of mid presence. You might have better luck moving the boxes well away from the back wall to check things, rather than changing part values. The 4 KHz crossover is quite high so not sure a change there would effect the mid-range or sound you are looking for.,so it maybe best to leave the caps alone. Have you contacted the kit seller regarding speaker placement and options?

[PeteMcK]

reducing the value of the inductor will allow the woofer to pass higher frequencies, but this changes the relative efficiency compared to the tweeter, and would normally require a tweaking of the tweeter L pad to keep the levels of the two drivers in balance

[DaveG]

Hi Manimal,
Have you played around with the line stuffing. Is it possible that the dampening in the transmission line could be effecting the mid bass?
A mid bass/upper bass bump would seem to mask detail.

[jerome69]

Hi,

Can you give us a schematic of your crossover ?

The 2.2mH is a minimum value...

Do you listen the speaker closed the wall ? too closed ruins the sound.
Also as said take a look to the damping of the line, very important.

[jerome69]

I see the crossover on your picture, the only suggestion I have is , you can put a 0.15uF capacitor in parallel of the 2.2mH to suppress the 9kHz peak.
Perhaps you have too many bass closed the wall ?