Paradigm Monitor 5 v2 Repair

Repairing the Monitor 5v2

Project Overview

The first couple generations of the Monitor series were well known for tweeter failure Adding insult to injury Paradigm no longer has spare tweeter parts for these units. This leaves many owners of these speakers in a bad place. So far I have resurrected a pair of Monitor 3v1 and now the Monitor 5v2 by replacing the tweeter with something still available. This page describes the repair for the Monitor 5v2 only.

As usual this repair was done as a hobby. I believe the end result was well worth it however if you choose to try this out you do so completely at your risk.

Materials

Paradigm designed this series with the tweeter faceplate and the grill working together to shape the response. Tossing in any tweeter will not yield good results; the stock faceplate must be used. This narrows the usable tweeters down to a couple. The old Vifa D27 series has the exact bolt pattern and diaphragm design to work with the stock faceplate. I used a Vifa D27tg05 because I had a pair on hand. Other options still commercially available are the Scan-Speak Discovery H2606/9200 or D2606/9200. Curiosity got the better of me and I ordered a pair of the ScanSpeak H2606 to try out. I wanted to see if they were a drop in for the older D27 and Solen had them on sale to boot. After some testing they are confirmed to be a drop in for the D27. If someone wanted to repair their speakers we might be able to work something out.

These speakers are starting to get up in years and changing out the capacitors might not be a crazy idea. Standard issue electrolytic are fine, perhaps a cheap poly cap to replace the 4.7uf. Mine still measured in spec so they were reused. Besides the caps and tweeters a few other items will be needed for both repair options shown on this page.

Option 1 - Minimalist

Option 2 - Perfectionist

Tweeter

First task was to mate the new tweeter to the original faceplate. They would bolt right up except for two issues. The Vifa/Scan-Speak dome assembly has the terminal lugs on the corners of the triangle shaped assembly. The stock diaphragm has the terminals more in the middle of the assembly. I have seen some other DIY'ers on the net do a similar swap and all they did was shave some plastic on the stock faceplate to clear the terminals on a Vifa tweeter. This brings us to problem number 2. The Vifa\Scan-Speak fabric dome is actually taller than the OEM Paradigm. Without doing additional modifications the dome can come into contact with the dispersion lens on the faceplate, not good. Easy fix here is to simply remove the dispersion lens. Testing shows the lens works with the original metal dome and works against the fabric dome of the D27. To show the effects of the lens on the new tweeter a couple response sweeps were taken of both the stock and new tweeter. All of these sweeps shown were taken without any crossover connected. Also noteworthy is the cabinet needs to be notched to clear the terminal connectors of the new tweeters. Easy to do with a dremel and spiral cutting bit.

Clearly the dispersion lens is not wanted with the replacement tweeter and the basic response matches nicely with the stock tweeter after its removed. I used small wire cutters to nip it off and a dremel to clean it up. The only downside to doing this is the possibility of putting the speakers back to complete stock trim is over unless entire tweeter assemblies were located. Be careful as the v1 and v2 faceplates look similar they are different enough to matter.

Options Options Options

Now that a tweeter is workable what to do with it. The response differs enough from the stock unit to prevent just dropping it in and calling it done. Doing so will leave you with a peaky response that is overly bright and just sounds wrong. After working with a Monitor 3 v1 and Studio 40 v3 I learned a lesson with the D27. The original Vifa D series always had a faceplate which recessed the dome back about 5mm. This was obviously done on purpose and I tried replicating this with both the Monitor 3 and Studio 40 with success.

This leaves two options to repair the Monitor 5 v2, the minimalist and the perfectionist approach.

Option 1 - Minimalist

This option is to get them running as simply as possible while maintaining the stock sound. As stated above dropping in a new tweeter requires more work to do this. The basic steps are remove the dispersion lens and trim some plastic on the backside to provide clearance for terminal connections. The crossover will need a couple modifications to shape the new tweeter. The 3.3ohm resister (labeled R3 on PCB) is removed and replaced with a jumper. A 15ohm shunt resister is added to create an L-pad for the new tweeter.

I only had a single functional stock tweeter and was never able to listen to these in stock form but I believe these mods will bring it as close as possible. In their own right they do sound very clean and neutral.

As can be seen in both responses, Paradigm did not shoot for a flat response with this speaker and for good reason. I tried using the tweeter in this configuration and tested several crossovers which provided a flatter response. They all sounded horrible. Either something is going on that I don't have the skills to measure or Vifa is correct by spacing the dome back 5mm from the surface of the faceplate. This is where the perfectionist approach comes in.

Option 2 - Perfectionist

I had two goals for this. Make the new tweeter seem as if it was part of the original design and use as much of the stock crossover as possible. This requires several modifications, removing the dispersion lens, spacer to recess the dome from the surface, more extensive crossover changes.

After some testing (which I won't bother posting) I ended up with a spacer about 3.5mm thick. The stock v2 faceplate already has about 1.5mm lip and this brings to where we want it. This spacer goes in between the magent assembly and faceplate. It also has the job of holding the diaphram in place. Using a spacer like this mitigates the need to trim the back side of the facepate for the terminal connectors.

The faceplate is designed to press down on the diaphragm evenly around the dome and line up with the 3 raised tabs on the magnet. When the faceplate is bolted tight it can only put so much pressure on the diaphragm before coming to rest on the raised metal tabs keeping the pressure uniform. I used the .020" plastic to create a ring which is glued to the tweeter facing side of the spacer. This will press the diaphragm tightly against the magent assembly. Some washers were made out of the same .020" plastic to rest the spacer on the metal tabs of the magnet. Without them the gap between the spacer and the magnet tabs will be too big and will bend the faceplate when it is tightened down. The Vifa and ScanSpeak tweeter versions have slightly differing heights here so an extra washer cut from the .020" pastic may be required.

The stock faceplate has a ring of plastic around the opening that is about .4mm taller than the bolt standoff. Some more washers are needed to take up this gap as we want the faceplate to push evenly on the spacer. I didn't take a pic of this as it simply is 3 more pieces of the .020" plastic glued to where the bolt standoffs are; exact same as on the other side of the spacer. To reassemble the longer 3x12mm bolts will be needed. When tightened up they should protrude from the metal tabs but not contact the magnet itself. All of this sounds complex but maybe took an hour to make 2 of them.

That’s about it for the tweeter. I took several impedance sweeps of each tweeter to ensure there weren’t any anomalies in the curves which might indicate an issue. They matched the curves perfectly that were taken before the modification.

I like crossovers designed by Paradigm. They always seem to have the simplest topology to do exactly what they need to and no more. I took several measurements and mocked up a computer model to simulate the design.

The new high pass circuit wants a 5.2uf capacitor in place of the stock 4.7uf capacitor. I say want becuase the computer sim shows it makes a reasonable difference yet actual measurements show less of a change. Options are to just keep the stock 4.7uf cap or parallel a .4uf cap to create the wanted value. I chose to parallel a .39uf film cap since I had one on hand and the 4.7uf cap still tested ok. The 3.3ohm resister is removed and replaced by a jumper on the PCB. The last change to the tweeter circuit is to add a 15ohm shunt resister creating a L-pad. Here is where the speaker can be adjusted to suit your preference. Reducing the 15ohm will provide additional padding and increasing it will reduce padding.

The new low pass circuit is altered to provide full baffle step compensation (BSC). Paradigm probably assumed customers of this speaker would likely have them near a wall and the stock lowpass reduces BSC accordingly. The larger 1.5mh inductor gets closer to full baffle step compensation. Use a steel core inductor to keep the DCR around the .35ohm range. The capacitor in the woofer circuit must be increased in value. The 22uf cap can be replaced by a 27uf cap OR a 4.7uf cap can be paralleled with it. This requires the PCB to be drilled for the additional 4.7uf cap. This is what I did and can be seen in the pics. The small .33uf capactor which bypasses the inductor creates a psuedo notch filter of sorts. Since this is not a 2.5way design the time delay of the lower woofer in reference to the tweeter changes with distance. Adding this tiny capacitor changes the rolloff of the woofers faster as the frequency approaches 6k. The end result, when the summed response distance is changed to 3m as might be a typical listening distance there is much less peaking in the 3-4k region.

The perfectionist definately has a warm sound thanks to the nearly full BSC. On high end of the spectrum they sound very balanced, high frequencies are there but not overbearing. For some magical reason using a spacer in the tweeter allows for a much flatter response without sounding harsh. Imaging is very nice and the speakers do a good job of disappearing.

I never tried listening to this option using the stock lowpass. It should be fine to leave it and continue with the tweeter and high pass circuit mods as given, I just prefer full BSC. If this is done I still highly recommend adding the .33uf cap in parallel to the inductor.

That's a wrap for this one. Hopefully someone will find this useful.

lord_darkhelmet at accesscomm dot ca

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