Could somebody check this XO Please?

[ODougbo]

This was a pre-made board and something seems fishy here. Could somebody check this please?

In particular the woofer circuit path:

IN bottom right, through the large coil, then terminated to the .22 smaller coil - then out

The speaker project is a 2-way - 832592 (8ohm) & MDT20

Other info: white coil is 16gauge sidewinder - smaller black .22 16gauge sidewinder

 

[dragonweed]

Without knowing the schematic and the woofer (832592?) it is pretty difficult to tell anything about your XO......

 

[Scottmoose]

Pass. Need to know the drivers + their impedances & frequency response as mounted on the baffle. Without that, it's just flailing in the dark.

 

[Lojzek]

IN bottom right, through the large coil, then
terminated to the .22 smaller coil - then out

It appears your LP filter is a 3rd order electrical with a C in series with R.
Caps 10uF +12uF look to be in parallel with RC. I could very well be wrong
about it.

L1=0,85 mH
R=8 ohm, C=22uF
L2=0,22 mH

 

[ODougbo]

OHHH Third Order - was comparing it to a 2nd. Never would have guessed that!
No schematic, it would be nice to have one, was going to try to sketch one up.

Attached PDF for the WR130; never knew why they stopped making it, affordable, easy to work with....

Thank you.

 

[theyoungone]

Assume this is the tweeter?

Morel MDT-20 1-1/8" Soft Dome Tweeter

 

[ODougbo]

Yes that is the tweeter.
The story is my friend upgraded their system and returned the speakers/boxes to me and now have a second chance to rebuild them.
Leaning to a 10 liter, rectangle box.

 

[Dissi]

I'm not sure at all if the attached schematic is correct, but it looks like a 2 kHz crossover without any baffle step correction. No bass and too much mids and heights?

 

[ODougbo]

Thank you Dissi!

The 22uf (10uf & 12uf) is curious, why didn't they use two of the same 22uf caps.
Three caps to ground that seems like a heavy load for a woofer that is known for a smooth response.
Tweeter circuit - it's a L-pad I think; there's a hidden 2.5ohm resistor behind the coil.

The bass may be lacking, it was screaming at me when I disconnected it, but that was only for a few seconds and this was now a Salvage Operation.

So yesterday went for it, ran the whole box through the saw and cut off the front baffle and started over. This time with felt lining, close tolerance driver recesses, moved the port and rounded over all the edges.

 

[ODougbo]

Finished it up and listened - oh boy it's awful.
Really thin, cold, predominate mid-range.

Even checked the tweeter in case it was not working - but fine (not blown).

 

[ODougbo]

Re-thinking this box, any thoughts about using a XT25 instead of a MDT20?

 

[ODougbo]

Thinking my best bet is to replace three components:
8ohm WR130 Woofer
MDT 20
LEAP XO
Nothing about this combination worked and the mini 1" x 3" speakers in the TV sounded better.

Going to try:
4ohm WR130 Woofer - with phase plug!
Vifa XT25
DIY XO (Thank you System 7 (Steve))

 

[Lojzek]

Morel tweeter should be fine. The issue is in the XO filter,
not the drivers. Need to measure it and then you will know
what to do with the filter. Industry standard filter for a bassmid
unit like this would be an inductor in the range of 2 mH
and a 6,8 uF cap for a 2nd order electrical.

 

[ODougbo]

Thank you Lojzek.
Q. Have a XLR/RCA mic mixer (in & out) do I simply use the headphone & mic 1/8" mini jacks on the computer for the connection points?

Downloaded ARTA a long time ago, never used it though.

 

[system7]

ODougbo, I don't really know quite what that old crossover that you credit to me is.

It sure looks wrong though. Polarity on the tweeter looks wrong, for a start. For a 5" 4 ohm polycone, and a simple circuit, we might be looking at something like the Epos ELS-3 design below.

But I doubt it'll be exactly right. More a point of departure.

 

[Lojzek]

I would recommend a simple approach measurement software
like HOLMImpulse to start with. Try any of the inputs/outputs
available on your sound card with a sampling frequency that gives
you best results on loopback test of the card itself and then
proceed with one channel of an amp and driver under test.
A flat FR is a sign of proper working measurement gear.

 

[ODougbo]

Okay HOLMImpulse
Will use one channel, the hook up should only take a few minutes with the mic mixer and mini-to-rca cables.

Steve, that xo design was a long time ago using a 4 ohm woofer.

It would be nice to revive this using the 8ohm 5" mid-woofer and the Morel 20. They are not very old and not showing any signs of wear.

 

[system7]

I can't keep up with all this mission creep! What is it? 4 or 8 ohm 5" polycone? What tweeter?

For 8 ohm, this Troels design is good. It even offers the XT25 or a regular DX25TG soft dome for choice. How flat your woofers are remains a variable. The 830860 is very flat. 0.7mH Le IIRC.
Peerless HDS PPB 830860

Oh wait. I just looked up the Peerless 832592. It's quite high inductance @ Le 1.1mH and not very extended, rolling off sharply at around 5kHz:
http://www.parts-express.com/peerless-832592-classic-5-woofer--297-622

That's quite hard.

 

[system7]

NOW i see where this is all coming from.

http://www.diyaudio.com/forums/multi-way/214180-2-way-crossover-design-help.html

Only this time we aren't time-aligned. Hence the polarity discrepancy.

Coil and Zobel bass filter. 2nd or 3rd order tweeter. Should work OK.

Please God this doesn't go on for 16 pages this time.

 

[ODougbo]

Oh that British Humor cracks me up every time ok less than 16 pages.

Lojzek thanks for the lead on the HolmImpulse download - very easy. Actually had a DIY speaker testing mic with 9volt pre-amp attached at the base

Tried the setup many times at slightly different positions; this is a more or less a middle-to-average result. The phase looks suspicious

Driver used:
http://www.parts-express.com/pedocs/specs/297-622-peerless-specifications-45026.pdf

http://www.parts-express.com/pedocs/specs/277-030-morel-specifications-44354.pdf