I ordered the basic RM30 last year as I was buying these speakers unheard and wanted to limit the cost should I not like them. I ordered the version without side-firing 10" drivers (C) as I use corner Tact subs with digital crossovers.
Once I got them and ran them in a bit is became clear that these speakers were something special. It thus made sense to look at the upgrades available.
I had (and continue to be) been a bit concerned about the upper bass / low mids. In my acousticall treated room and with a listening distance of about 10', the speakers being about 9'apart, there is a dip in the frequency response between 400-700Hz. This, I think, reflects more the listening distance, floor reflection, and panel impulse response rather than any inherent "deficiency" in the speaker design.
After discussions with Brian and John Casler, both of whom were very helpful, I decided to order the 6.5" megawoofers and Auric cap upgrade. They arrived in January and cost me quite a bit mainly due to the transport costs to South Africa.
The original woofers were a pincushion shape whereas the megawoofers are round - this required routing the openings a bit in order to fit the megawoofers. It was quite a saga to locate the right router bit as well as the woodworking skills - fortunately a friend was able to help me and it went fairly smoothly without any damage to the finish on the speakers. Unfortunately, the openings still show a bit of the pincushion extensions so the finish is not perfect. Still, it looks fine.
There was a difference in the way that the passiver radiators were fixed to the box on the one speaker - it seems as if one of the holes had been cut too big and a mounting plate was added to reduce the size of the opening, the PR being fixed to this. Not a major issue but clearly a mistake by the box builders.
I then started with the capacitor upgrades. Getting the boards on which the x-overs were mounted out was a bit tricky - the glue is a pain in the neck. I decided to mount the crossovers on new boards which were placed on the side wall of the speakers, allowing me to place three sets of binding posts on the back openings to allow for bypassing the passive crossover with digital ones. Before starting the crossover mods, I took a lot of digital pictures of the existing components which was very useful in later ensuring that I connected the components correctly.
The large Auric cap was a different value to the original (53uF vs 41uF) which would obviously make it difficult to compare the intrinsic benefit of the capacitor upgrade. I could not tell the differences between the new and old tweeter caps due to glue on the old caps obscuring the text.
The crossover components were all glued down carefully to avoid vibration and to prevent the heavier components such as the inductors from slipping off. This part of the mod was a pain and I sympathise with Brian for the laborious effort required in modding equipment. Working throught the PR holes and the woofer holes made the mod possible but it was certainly fiddly and time-consuming for a relative novice.
I also added bitumenized panels to the side walls of the speakers which seemed to decrease the resonance of the speaker box - whether it would do anything to the sound was unknown.
Brian also sent me some lambswool which I placed behind the mid panels - I thought I had blown the panels in one speaker as there was a lot of distortion from the one side - fortunately it was only due to the wool pushing against the back of the one panel. Once I repacked it, the noise disappeared.
I also soldered the woofer wires directly to the speaker poles and removed the connectors that were previously used. Additional wires used were DH Labs silver coated copper.
Eventually all the mods were all done and I tested the speakers to see that all was ok. I then ran them in with the burn-in track from Ref Recordings for 5 days before doing any serious listening.
I ran the usual Tact measurements which are necessary in order to implement room correction. I was disappointed to see that the dip between 400-700 persisted but was not overly surprised. The rest of the measurements remained similar.
On listening however I was very pleased with the sound. The mids sounded clearer and the mid-bass more controlled if still somewhat subdued. Removing putty on the PR's had little effect.
I have subsequently bypassed the woofer crossover and am using a 550Hz 8th order low pass cross on the woofer to fill in the room response dip. This has certainly improved the upper bass and low mid quite a bit. I get the feeling that the megawoofers are designed to work lower than this but still, overall the sound is better.
The mods were finished almost two months ago and during this time I have been playing around a lot with digital crossovers etc. I still cannot run the speakers entirely with digital crosses as I need one more amp. Still, at least the speakers are set up so that bypassing the passive crossover is very easy. If anyone is interested in the details of how to do this they are welcome to contact me - not because I am an expert but merely because they may avoid making the same initial mistakes I did
While listening this weekend, I asked myself if this had all been worthwhile? I cannot compare the before and after version of the speakers and have had to rely on memory to assess them. What I can say is that the speakers are sounding superb and any frustration I may have experienced during the mods has long been forgotten.
Finally, I had not listened to my previous speakers since getting the RM30's. I have currently got the new version of my speakers from the speaker builder to assess. They are beautifully built (better than my RM30 - sorry Brian) and also sound better than the earlier version. After a few days however I had to put back the RM30's as I really missed them - I think that says it all.
I am not saying that the RM30's are perfect but they are a lot better than anything else I have had or heard and I love listening to them. Brian, congratulations on your design, for the price they are unrivalled.
Regards
Jose
