Does anyone sell off the shelf low pass filters in UK

[bumpy]

I want to experiment changing the low pass filter on the 15 inch driver in my 3 way open baffles. At the moment the output from the 15" bass driver is intruding too much on the midrange. It crosses over at 400-500 Hz and I would like to try 100 to 150 Hz.

Does anyone in the UK sell 'off the shelf' low pass filters? Cost is of the essence while I experiment. I have a microphone and REW software so I can monitor the output.

Just thinking aloud, but a passive variable low pass filter would be great if such a thing exists.

[Puffin]

There is a simple DIY low pass sub on the link below. A 6.5mh inductor costs £10 at Mouser. 6.8mh at CPC is £7.70.

I built a passive sub many moons with an inductor and cap and it worked ok.

http://techtalk.parts-express.com/forum/tech-talk-forum/49536-passive-subwoofer-d-i-y

https://cpc.farnell.com/w/c/electronic-electrical-components/inductors-filters/inductors/prl/results?st=Inductor

[bumpy]

There is a simple DIY low pass sub on the link below. A 6.5mh inductor costs £10 at Mouser. 6.8mh at CPC is £7.70.

I built a passive sub many moons with an inductor and cap and it worked ok.

http://techtalk.parts-express.com/forum/tech-talk-forum/49536-passive-subwoofer-d-i-y

https://cpc.farnell.com/w/c/electronic-electrical-components/inductors-filters/inductors/prl/results?st=Inductor

Thanks Puffin
At present I have been totally put off DIY. Recently I wanted to add a bit of extra attenuation to a passive volume control. Strictly following advice on here I bought a couple of resistors and soldered them in circuit exactly as suggested. The result was a couple of loud bangs and a firework display from my vintage Saba green cone drivers They had survived from the mid 1950s but are no more - voice coils melted and twisted and paper cones torn to shreds.

[Puffin]

Chris, i don't think you can go far wrong with the circuit I posted. You certainly wouldn't blow anything up......would you?:eek:

I have a pair of Lampizator OB's with SABA GC's HF and Mids gathering dust. I was never that smitten with them, but last used them about 2 years ago. I have thought of selling them, but I don't know.

EDIT: I have just remembered that I have a pair of built crossovers on PCBs for (I think) a 3 way speaker that I got from an Audiojumble years ago. They appear to be new and unused. I have never got around to doing anything with them. I am pretty sure that they have a Sub connection, but I will need to find them to confirm. If these are any good to you.....?

EDIT 2: Bummer, they are only 2-Way HF and LF, mind you the inductors are enormous, but no visible specs.

[bumpy]

I think I have found another way to sort this. The current inductor on the bass driver is about 4mH and my calculator suggest 10 mH is needed.

I have discover in my bits and pieces a pair of inductors that I stripped out of an old pair of Radford speakers. I believe them to be about 6mH.

Can I solder the two inductors (4 and 6mH) in series to give 10mH. Is it as simple as that, with no need for concerns about polarity?


28329

[Pharos]

Yes, but you have to consider the orientation of the turns, if opposite you will get cancellation. Also consider the proximity to each other and any change in value that might have due to magnetic coupling.

[bumpy]

Great point about the magnetic fields. To be absolutely clear. I guess this is the worst case

28343

[bumpy]

And this is the best. With as much social distancing as can be achieved

28344

[bumpy]

Anyone?

[bumpy]

Sorry to go on a bit, but is there anyone can confirm I have understood the inductor orientation correctly. Have been patiently waiting a week to do this job.

[Pharos]

In your post 8 one coil needs to be turned 90 degrees so that they form a 'T' to uncouple the fields as much as possible.

Looking at crossover networks shows this is done usually.

[bumpy]

Thank You Dennis :)

[bumpy]

This very useful link was sent to me by pm. Thanks Richard

http://www.troelsgravesen.dk/coils.htm

[sailor]

Hi Chris, from your post 8 just change the position of the coil that is upright. To be clear, the one that could act as a wheel and roll around should be rotated 90 degrees as depicted in Fig.5 in the link provided. If the coils are from different sections, say one is for the woofer and the other for the mid or tweeter the orientation in FIG.5 should be adopted for the least interference between the two.(crosstalk)

In Fig.7 he states 'never do this' which in fact is desirable if you are combining coils to achieve a certain value and works to your advantage. Less real estate is required, there is less spread of magnetic fields and you save copper. Crosstalk in this case is no problem as they are part of the same filter.