Cheap analog electronic crossover

[Sokel]

I've been playing lately with a very cheap analog 2-in/4-out analog crossover.
Is somehow DIY but very easy to fix.
To my surprise it measures very decently!
(note that has been measured with the worst possible conditions,long cables soldered just to see,adapters,noisy PSU and by someone totally newbie in measurements-me)

(the conditions)


Despite all that...

Low's

High's

Decent slope

If there is any interest I can put the link later.
Point is that are solutions that don't require lots of money and 30 euros is nothing to ask for such performance.

MCRS-2BI or MCRS-2BI3 2Way Bi-Amp Active Stereo Electronic Crossover 24db Low/High Filters - Motronix

MCRS-2BI MCRS-2BI3 High Quality Professional 2 Way Electronic Crossover For Active Bi-Amplification. High Quality Low Noise Op Amp MCRS-2BI model Work with Small Dual AC Transformer (Transformer not included) MCRS-2BI3 model Work with Dual 15-20Vdc Power Supply Low Freq. Range <250 Hz (Can...

motronix.co.il

 

[MCH]

Do they sell them with different xover frequencies?

 

[Sokel]

Do they sell them with different xover frequencies?

Yes,you select every freq you want on checkout.
You also have a choise to power it with a simple transformer,you don't need the 15-0-15 version which I got if you like.
There are also 3-way,1-way,etc.

 

[Sokel]

For the friends who want to cross subs,take a look at the low's.

Totally decent.

 

[gene_stl]

Link please?

 

[Sokel]

Link please?

MCRS-2BI or MCRS-2BI3 2Way Bi-Amp Active Stereo Electronic Crossover 24db Low/High Filters - Motronix

MCRS-2BI MCRS-2BI3 High Quality Professional 2 Way Electronic Crossover For Active Bi-Amplification. High Quality Low Noise Op Amp MCRS-2BI model Work with Small Dual AC Transformer (Transformer not included) MCRS-2BI3 model Work with Dual 15-20Vdc Power Supply Low Freq. Range <250 Hz (Can...

motronix.co.il

(I will also add it in the first post,it ships from Israel)

Edit: I asked them to not solder the stereo pots as I wanted to put trimpots for every channel so I have freedom of adjusting them.

 

[Plcamp]

Good ones here…https://www.xkitz.com/collections/active-crossovers-and-bi-amplifiers-1

They use plug in modules for freq selection.

 

[Sokel]

Good ones here…https://www.xkitz.com/collections/active-crossovers-and-bi-amplifiers-1

They use plug in modules for freq selection.

They seem really nice but you need two of them for stereo plus the PSU so the total goes to 130$ at least.
No comparison to 30$ plus a 10$ transformer 12-0-12 for the AC version.
That's why I said cheap (and decent)

 

[Sokel]

That's with a little care and a hand made double LM7815 (that was what I had in the drawer,the old DIY way to get 15-0-15V) in an old case:

...and with a lot of averages to reveal every little spike:

That's the cleaner I could get it so far.


Edit:
Note that all measurements are in dbfs scale,not dbA.It would be better will the later.

 

[hdw]

That's with a little care and a hand made double LM7815 (that was what I had in the drawer,the old DIY way to get 15-0-15V) in an old case:

View attachment 233526


...and with a lot of averages to reveal every little spike:



View attachment 233527

That's the cleaner I could get it so far.


Edit:
Note that all measurements are in dbfs scale,not dbA.It would be better will the later.

Hi Sokel! Was wondering if you still are using the Motronix crossover you talk about here and what your experience has been. If positive I'm considering using one on a Martin Logan Sequel II................

 

[Sokel]

Hi Sokel! Was wondering if you still are using the Motronix crossover you talk about here and what your experience has been. If positive I'm considering using one on a Martin Logan Sequel II................

I use (or to tell the truth,play) with several and this little thing has proved to be really nice with a little extra care.
A basic well made PSU,a case to shield it a little and voila:

Noise went down by a good margin,basically as transparent as it can be.
(it must be even better than it looks at the measurement cause these are the limits of the DAC part of the loopback )

There are even nicer models of motronix as I had a look which they don't cost much more,consider those as an option as well (never had one in hand to measure but it seems these guys know what they're doing and they are dirt cheap too) .

 

[Roland68]

I find these modules very interesting.
https://www.ebay.de/itm/393525534214?hash=item5b9ff31e06:g:NtoAAOSwjQNhImoi
Has anyone tried them yet?

 

[Sokel]

I find these modules very interesting.
https://www.ebay.de/itm/393525534214?hash=item5b9ff31e06:g:NtoAAOSwjQNhImoi
Has anyone tried them yet?

They report close to 90db THD (no noise figure reported).
I think asking price (close to 150 euro for 2 in-4 out along with the phase shift board if I got it right) is too much for what it gives.

 

[Roland68]

They report close to 90db THD (no noise figure reported).
I think asking price (close to 150 euro for 2 in-4 out along with the phase shift board if I got it right) is too much for what it gives.

I would just buy the circuit boards for around €50 and assemble them myself.

Can you change the crossover frequencies yourself with the MCRS-2BI2/3?

 

[Sokel]

I would just buy the circuit boards for around €50 and assemble them myself.

Can you change the crossover frequencies yourself with the MCRS-2BI2/3?

Theoretically yes,but it needs soldering,etc.
If you want to play around with variables consider Marchand boards as well,the ones I have measured just maxed at the limit of my ancient measuring interface and they have lots of options too (but not as cheap,about 100$ each the unpopulated boards and you will need 3 for a 3 way) .
Another good option is the ones another friend posted in this thread but they report some strange specs in the 80db SINAD area which must be wrong,the parts used are really good.

If you're about to do it yourself I would certainly try the one you posted,lots of options.If only we could measure it,I don't worry about distortion but noise (not in the specific one,I mean in general)

 

[Roland68]

Theoretically yes,but it needs soldering,etc.
If you want to play around with variables consider Marchand boards as well,the ones I have measured just maxed at the limit of my ancient measuring interface and they have lots of options too (but not as cheap,about 100$ each the unpopulated boards and you will need 3 for a 3 way) .
Another good option is the ones another friend posted in this thread but they report some strange specs in the 80db SINAD area which must be wrong,the parts used are really good.

If you're about to do it yourself I would certainly try the one you posted,lots of options.If only we could measure it,I don't worry about distortion but noise (not in the specific one,I mean in general)

Soldering is no problem and thanks for the other recommendations.
Analogue active crossovers seem to be a very small market, especially in the cheaper and DIY range.

There used to be various crossover boards/PCBs on eBay from KMtech in the UK, but apparently they no longer ship to Germany.

 

[Sokel]

Soldering is no problem and thanks for the other recommendations.
Analogue active crossovers seem to be a very small market, especially in the cheaper and DIY range.

There used to be various crossover boards/PCBs on eBay from KMtech in the UK, but apparently they no longer ship to Germany.

I tried a couple of countries in Europe and they do send it from here https://www.ebay.com/str/kmtechdesign
Otherwise there's must be a third-party service to do that for you for a small fee if I remember well.

They seem nice.

 

[JohnnyNG]

For an idiot with little electronics knowledge (asking for a friend), might it be possible to post links to what would be needed to get it working?

 

[Sokel]

For an idiot with little electronics knowledge (asking for a friend), might it be possible to post links to what would be needed to get it working?

For the specific one a regulated PSU like this (I choose this so you don't have to g elsewhere) and a transformer (link describes what trafo)

M78-79REG Dual Voltage Regulator Module (For AC 0 AC Transformer) - Motronix

M78-79REG Dual Voltage Regulator Module 12Vdc or 15Vdc or 18Vdc Positive/Negative PCB With 7812-18 & 7912-18 Especially For Audio Applications Input Voltage : 2X12-16Vac (For models with +/-12Vdc & 15Vdc) 2X15-22VAC (For model 2X18Vdc) Output Voltage: +/- 12VDC +/-15VDC +/-18VDC Output...

motronix.co.il

For the AC version just a transformer.
In both cases a 2x15V 30VA transformer will be fine (I don't put a link,there's a gazzilion of them,choose according to your wallet)..


Edit:
This one will not even need a transformer and it's on stock,so go for this and the DC version of x-over (the one of this thread,MCRS-2BI3)

MPS-DV2S/DV1S 110/230Vac to Dual Regulated 12-18Vdc (+ 0 -) Power Supply for Audio Pre Amplifiers - Motronix

MPS-DV2S / DV1S Power Supply for Audio Pre Amplifiers ***On board 2 Molex standard connectors for all Motronix products*** 115/230Vac 50/60Hz Input Dual Regulated 12/15/18Vdc +12V 0 -12V 2x200mA +15V 0 -15V 2x160mA +18V 0 -18V 2x100mA Compact Size Board Product For Audio Applications Double...

motronix.co.il

 

[hdw]

For the specific one a regulated PSU like this (I choose this so you don't have to g elsewhere) and a transformer (link describes what trafo)

M78-79REG Dual Voltage Regulator Module (For AC 0 AC Transformer) - Motronix

M78-79REG Dual Voltage Regulator Module 12Vdc or 15Vdc or 18Vdc Positive/Negative PCB With 7812-18 & 7912-18 Especially For Audio Applications Input Voltage : 2X12-16Vac (For models with +/-12Vdc & 15Vdc) 2X15-22VAC (For model 2X18Vdc) Output Voltage: +/- 12VDC +/-15VDC +/-18VDC Output...

motronix.co.il

For the AC version just a transformer.
In both cases a 2x15V 30VA transformer will be fine (I don't put a link,there's a gazzilion of them,choose according to your wallet)..

Additional "asking for a friend" questions:
Would the DC PSU Motronix sells be quieter than an AC transformer?
Should the PSU be kept separate from the crossover (mounted in a separate box)?
Should the box be metal or is plastic OK?
Are there other considerations for keeping things quiet (hum free etc.)?