After a couple of weekends, finally I have some comments on my recent tests in order to enlarge the sound capabilities of THR and avoid this "rattling" related with high volume limits.
I tried three different configurations with my THR10C:
1) THR plugged into linear power amplifier and passive loudspeakers through headphone output.
2) THR plugged into active monitors Yamaha through headphone output.
3) THR plugged into passive cabinet taking the power cables from the THR power leads.
Configuration 1 and 2, I don’t know why exactly, aren’t bad, but definitely sound different and much worse than the THR “pure” itself. OK, there is much more volume and you can have a wider stereo sound, but overall sound quality is poor and compressed.
Configuration 3 is fantastic. I had already available at home 4 cones Monacor Sp200x. They are full range 8 inch woofers with a quite good extension until 15 kHz. I tried 4X8 configuration and 2x8 configuration. I can say that 2x8 was better (probably THR is more happy to have 8 Ohm instead of 4 Ohm impedance…). Once selected the 2x8 configuration I also added a piezo tweeter (Motorola KSN) with a very simple capacitor filter to have the full specturm until 20 kHz. These tweeters are very directive, so that I put it on the back of the cabinet, in order to have some presence in the room.
The tweeter is adding some “tzing” and “air” when using acoustic guitars, but could be also to much “tweety” in other situations, so that I think is matter of personal taste. An option could be a simple switch in order to engage on-off the tweeter as desired.
Opinion: that combination 2x8” (with or without tweeter) is amazing. The THR has a LOT of power and the resulting sound is very open, clean absolutely without any “rattle”… All the effects become very sensitives… The reverbs, the chorus etc are much more present and you need a more fine tuning of that.
Using these full range drivers you can have a quite similar tone compared with the original THR speakers. The overall sound is anyway different because of the cabinet influence, the driver specs and much more air moved by the system in the room. You have to change some bass/mid/treble Eq in order to have exactly your sounds. The overall volume its quite high, enough to play in a small jam session with friends ! I can imagine very good results also with coaxial car drivers in the 6 inchs size… Monacor Sp200x is only one driver possibility. What you need is a full range driver with good quality, extended frequency response, nice Qts and Re higher than 6 Ohms.
Next steps: these tests have been made “quick and dirt”, using rubbish materials available at home and making electrical connection with “flying” wires and fasteners here and there… Now I selected my preferred configuration and I’ll realize the final version (2x8”) with good wooden quality and I’ll put two switching jack output to the back of my THR in order to plug easily the external cabinet into the THR. I will do an open back cabinet (about 70 x 40 cm), vertical and a bit slanted, with the two drivers out of axis in order to have some stereo emission.
I hope this is useful test for some of you wanting more volume. Looking forward to your tests and comments ! I really hope Yamaha will go further with this THR technology because there is a big potential in that and they have for sure much more expertise than I !
