modding Inter-M DIV-9123 electronic crossover

[col]

I recently picked up a secondhand Inter-M DIV-9163 2-way stereo + sub woofer out, electronic crossover on ebay and would like to use it with my 41hz amp9-basic (4 channel) and a Hypex 2.1 sub plate amp, powering some seas 5" woofers and 1" silk dome tweeters with a Peerless 8" sub. I want to completely dispense with any passive crossover components in the speakers.

I am looking into using some Nuetrik NTE1 or NTE4 transformers for balancing up the connections going into the amps.

Looking under the hood of the crossover it seems very conducive to being modded

There are no SMD components and the PCB looks like it has fairly thick tracks and all the op-amps look ancient. So I guess that is a good place to start.

A few pics:

http://pix.minirig.org.au/main.php?g2_itemId=291

The op-amps in the output stage are JRC5532DD

and the ones in the filters are JRC4558D

Iv'e been doing some searching through the forums and it looks like there are plenty of compatible, more up-to-date op-amps that could be swapped in, infact there are SO many

Was wondering if anyone had any suggestions on what to use that I could follow up on? Would it be a good idea to replace the op-amps with sockets so I could try a few different types, if so what ones.

I am also contemplating changing some of the pots as I noticed that there is some noise when the pots are in the half-way position but I have know way of knowing what value the current ones are? Also, the noise might not be the pot itself?

Any help would be much appreciated. There is a not very good schematic online for it too.

 

[col]

have been reading as much as I can about op-amp upgrades and I think my plan of action is going to look like this:

1. remove all the op-amps and fit DIL8 sockets

2. purchase 16 TL072 and 16 NE5532 for the filter section, replacing JRC4558D these are cheap so I can do a comparison test between the TL072 and NE5532

3. purchase 7 OPA2134 and replace the JRC5532DD or the in/out stage

I'm also thinking of replacing the 150mA 5VA 2x15v transformer with a 200mA 6VA 2x15v one and upgrading the supply caps from 1000uF 35v to 1800uF 35v. The specs for the regulators say they can handle 1A so I guess that should be within tolerance. There are 2 x 220uF caps just after the regulators. I'm wondering whether to upgrade those?

Have been looking at the pots and comparing them with photos online. It looks like they are mainly 10k linear alps. So I might just leave them as is.

 

[col]

op-amps upgraded

I have completed the first lot of upgrades to the InterM DIV-9123 and it has made a HUGE difference, totally opened up the sound stage. If any one out there owns one of these I highly recommend changing the op-amps!

Before and after Pics here:

http://pix.minirig.org.au/main.php?g2_itemId=291

I put sockets in then 7 x Burr Brown OPA2134PA in the input/output stage
and 12 x Texas Instruments NE5532P in the filters. I have some TL072 that I might try later.

Very happy with the sound at the moment though, think I will change the pots next as there is still some noise in them when the level is half way.

Op-amps were purchased from RS-Components.

 

[col]

Added bonus: mini Jaycar Pot

Found another gem that works with the InterM DIV-9123

The 9mm 10k linear Taiwanese Alpha pot will work as a drop in replacement with the level pots! Have to change the knobs though as they are splined.

See this thread for info on the superb Jaycar pot:

http://www.diyaudio.com/forums/showthread.php?s=&threadid=39258&perpage=25&highlight=&pagenumber=1

Hmm..... now for the downer. Iv'e lost the mono subwoofer channel

I'm not sure if it was there when I bought it as I never tested it, Iv'e been running it in 2-way mode up until now. Went to move it into my main system after taking the passive crossovers out of my mid-highs and then discovered the sub channel not working. Feeling a bit gutted as it is sounding superb with the mid-highs crossing at 3k. But I can't hook up the Peerless 8" sub

 

[col]

Swapped out the main board with 2 x ESP 09 and 1 x ESP 05

Just to finish off this thread.

In the end I gave up on the InterM DIV-9123 circuit board and swapped it out for two Elliot Sound Projects 24 dB/Octave 2/3-Way Linkwitz-Riley boards (P09) and the ESP PSU (P05). There is no comparison, the ESP boards are on a totally different level of sound quality and for the price are VERY good value and I got to use the op-amps that I bought for the original upgrade.

Some final photos of the modules in the case:

http://pix.minirig.org.au/main.php?g2_itemId=291&g2_page=2

http://sound.westhost.com/project09.htm

 

[col]

Added ESP P88 preamp and jaycar pots

opps.... added a preamp:

http://pix.minirig.org.au/main.php?g2_itemId=392

 

[peter day]

Point of origin

I was just looking at this active crossover pictured from '08 and couldn't believe how similar looking/in performance it is/was to a used Electro Voice unit I just picked up.

After seeing this same interM model listed at a bargain basement price on eBay recently I started looking a little closer at the numberous mods you made and I arrived at a few conclusions.

For starters, this interM company starts up in Korea in '04. A couple of years after the EV x23 was introduced. Layout between the two is identical. Hmmmmn.

Performance looks identical with one small issue. Power consumption is almos 20 percent higher for this seemingly identical unit. Hmmmn

You talked about replacing 'antiquated' op amps, and then even move on to replace a couple of entire boards with premium linkwitz riley filters. Hmmn.

Turns out my EV has these phase-aligning 24 db filters factory installed already.

My point is: Does interM ingore patents/design rights and then pump out similar off- shore products using cheaper, old stock components? Even their product manual was self-contradictory WRT distortion specs.

I am no electronics wizard, but I do appreciate and benefit from reading knowledge and experience posts which help make my purchases wiser.

peter