Hi -
When I posted initially I had the 20's, but now have the 20i's. Not long after my last post we had a baby, which scrapped my time to do any major "projects" for now - so I have not upgraded the 20i's at all - except to replace the woofer surrounds. I did do a side by side A/B of the 20's and 20i's before selling the 20's to a friend. The only difference was subtle and in the mids - slightly better detail. But frankly if I were not doing direct A/B, I doubt I would notice any difference.
The main reason I wanted the 20i's was for biamping without having to tear apart the crossover. I now run the mids/highs with a CJ Premier 11a and the bottoms with solid state. Frankly though, I'm not sure that the DQ circuitry is really well designed for the biamp configuration. I'm no expert in the nuances involved, but I notice that with the tube already amp on, the biasing changes when I power up the SS - which suggests there's a significant interaction going on between the amps... hmmmm. A friend of mine with 20i's tried a number of biamp arrangements (all SS) and decided that a single amp with adequate power sounded much better. So not sure what I'll do with that - I love the CJ's mids but it's bass is just too soft, at least with the sealed box DQ's.
re: Tweeters
Comparing the Freq Response graph of the 1" and 3/4 tweeters, I suspect that the 1" may cure much of the DQ's deficiencies. My measurements a while back (which I posted in some other thread here I believe) showed a dip centered around 3.5khz, which is EXACTLY where the 1" betters the 3/4" on the graphs - that's a pretty exciting find since that dip is what really holds back DQ's performance from being short of spectacular***. Not sure addition of a resistor would be necessary as the actual impedance plots vary by only about 1 ohm. (I assume you know this, but if you do include a resistor - make sure you use a non-inductive type.) I might first consider trying a double length run of higher guage (thinner) wire between the crossover and tweeter to bump up the resistance a bit.
Please let me know how the tweeter swap works out and I may follow in your footsteps!
***A lighter weight, more modern woofer probably would be nice too. The Alon V's did better their performance slightly.
re: Capacitors
On searching around a bit I decided it would be silly to go for the Regnar package, as I could probably buy V-caps or similar myself for less - especially if just recapping the mid/high circuit which is all I think would be necessary. I assume you've seen this recent thread re: replacing DQ caps:
http://forum.audiogon.com/cgi-bin/fr.pl?cspkr&1161475591&read&3&4&
I also mentioned in that thread a worthwhile alteration to the grills that is pretty easy. If you place your hand on them at even moderate volume you can feel very significant resonance. It's like having a passive planar radiator with a random freq. response added to the mix - not good. Damping that grill as much as possible is one of the more important upgrades IMO.
When I posted initially I had the 20's, but now have the 20i's. Not long after my last post we had a baby, which scrapped my time to do any major "projects" for now - so I have not upgraded the 20i's at all - except to replace the woofer surrounds. I did do a side by side A/B of the 20's and 20i's before selling the 20's to a friend. The only difference was subtle and in the mids - slightly better detail. But frankly if I were not doing direct A/B, I doubt I would notice any difference.
The main reason I wanted the 20i's was for biamping without having to tear apart the crossover. I now run the mids/highs with a CJ Premier 11a and the bottoms with solid state. Frankly though, I'm not sure that the DQ circuitry is really well designed for the biamp configuration. I'm no expert in the nuances involved, but I notice that with the tube already amp on, the biasing changes when I power up the SS - which suggests there's a significant interaction going on between the amps... hmmmm. A friend of mine with 20i's tried a number of biamp arrangements (all SS) and decided that a single amp with adequate power sounded much better. So not sure what I'll do with that - I love the CJ's mids but it's bass is just too soft, at least with the sealed box DQ's.
re: Tweeters
Comparing the Freq Response graph of the 1" and 3/4 tweeters, I suspect that the 1" may cure much of the DQ's deficiencies. My measurements a while back (which I posted in some other thread here I believe) showed a dip centered around 3.5khz, which is EXACTLY where the 1" betters the 3/4" on the graphs - that's a pretty exciting find since that dip is what really holds back DQ's performance from being short of spectacular***. Not sure addition of a resistor would be necessary as the actual impedance plots vary by only about 1 ohm. (I assume you know this, but if you do include a resistor - make sure you use a non-inductive type.) I might first consider trying a double length run of higher guage (thinner) wire between the crossover and tweeter to bump up the resistance a bit.
Please let me know how the tweeter swap works out and I may follow in your footsteps!
***A lighter weight, more modern woofer probably would be nice too. The Alon V's did better their performance slightly.
re: Capacitors
On searching around a bit I decided it would be silly to go for the Regnar package, as I could probably buy V-caps or similar myself for less - especially if just recapping the mid/high circuit which is all I think would be necessary. I assume you've seen this recent thread re: replacing DQ caps:
http://forum.audiogon.com/cgi-bin/fr.pl?cspkr&1161475591&read&3&4&
I also mentioned in that thread a worthwhile alteration to the grills that is pretty easy. If you place your hand on them at even moderate volume you can feel very significant resonance. It's like having a passive planar radiator with a random freq. response added to the mix - not good. Damping that grill as much as possible is one of the more important upgrades IMO.