From Bi-Amping to Tri-Amping !
I am finally close to acheiving my dream of tri-amping an extremely high quality system! I won't call it a "reference" setup, although it may come close in some areas when I am done.
I have had my nOrh system for over 8 years now: Marble 9.0s powered by Multiamps in bi-amp mode, with the ACA preamp delivering the sweet sounds from the tube-output CD-1 (a Cal Audio clone). So, that's 3 components and a pair of monitor speakers that can do 33Hz.
I did some real audiophile heavy lifting to get to this point! First the speakers weigh 80lbs. each, made out of marble boulders cut to a rough shape and turned on a lathe to shape them like a Thai drum. This manufacruing process is extreme, and only about 25% of the marble makes it to the shape of a drum! Still in Thailand marble is relatively cheap, and it has been economically feasible to manufacture these speakers.
I built special stands for them in my listening area - cinderblocks on a furniture dolly, wrapped in cloth! I wanted them to be stable, and movable, at least initially.
I listened to my speakers with the passive crossovers for a while.
Another challenge along the way was the fracturing of a couple of the op-amp chips in the Multiamps, after I had moved them using the handles! The handles caused some flex in the case, which distorted the chips - when the amps were powered on, the chips fried. This was not a fun experience, complete with pops and some smoke, but after a call to nOrh, they assured me I had done nothing wrong, how the damage was caused, and we arranged to ship them back for repair.
Meanwhile I had to replace a blown Revelator woofer
During this time without the nOrh amps, I used a Yamaha A/V receiver. Not nearly as nice as the Multiamps had been!
Once I got the Multiamps back from nOrh a few months later, after Curt Wishman had done a fantastic re-engineering job on them, I then took things to the next level - I rewired the Marble 9.0s for bi-amping with the Multiamps. THe Multiamps and the Marble 9.0s
were both designed for this capability and I had planned on doing this when I ordered them.
The Marble 9.0s use some fantastic drivers - Scanspeak Revelator 15W/8530-K00 woofers and Scannspeak Revelator 9900 tweeters. See here
http://www.audiocircle.com/index.php?topic=347.0 for a step-by-step of how I disconnected the crossovers and connected the woofer and tweeter to the 2 sets of binding posts.
Once they were rewired I had to carefully set the multiamps to function as vertical bi-amping crossover amps. This was not intuitive, but by carefully reading the manual as well as the back of the amp, I was able to get the settings right, and then adjusted the crossover point between woofer and tweeter.
After all these things were done, I ended up with a fantastic sounding system. During these years I spoke with a few other audiophiles who had Marble 9.0s and Multiamps, as well as with Michael Barnes of nOrh and Curt Wishman or IRD. I felt I was getting a lot out of this system and the synergy seemed to be in place. Curt, Tyson, and others told me that with subwoofers crossed over at the right point, I could really get the Revelator woofers to sing in the mid-range they were designed for.
The Marble 9.0s provide an amazing amount of bass when set up in my environment. I was able to understand the limits however, when I played certain CDs. I could tell there was more bass I was missing with some CDs, and one of them was the Telarc Organ Sampler. My measurements using a Radio Shack SPL meter also told me that I was not getting nearly as much as I could hope for.
I knew that to get to the point of adding subwoofers, I needed a few extra components. After bi-amping, I knew I would want to tri-amp with subwoofers. I also wanted a very high-quality tri-amping solution. My hope initially had been that IRD, headed by Curt Wishman, would develop their planned three-way electronic crossover. I had auditioned their Purist preamp, but did not want to make a move until the 3-way crossover was done. Unfortunately it was not to be - due to business circumstances, Curt had to put the project on hold indefinitely.
I had also heard of the Behringer DCX2496 in use as a tri-amping solution. My concern was that this unit was know to be often not of audiophile quality - there were noise issues, and the analog section was not up to standards that audiophiles strive for. These units were being modded to improve the quality of the solution, but I was not ready to go that direction, in addition to choosing an amp solution and subs that I would have to pay a nice sum for.
Finally circumstances worked out and I felt the time was right. I read Tyson's article about his quest for the next level, after having a heavily modded DCX unit in use with his latest speakers. He had obtainied a good deal on a DEQX HDP-3 Preamp Processor, which
gave him even more control and features than his special DCX. I saw my opportunity to pounce! Before Tyson could have a chance to put it up for sale, I asked him about his DCX. I had read a little bit about how it was mgalusha's "masterpiece" DCX modification, after experience with several other DCXs mods he had done, and I did a little research and talked with Tyson. This mod of the DCX focused on the DAC and the analog sections. I decided that this was the one to go for, and made a deal with Tyson. He shipped it to me, and I have just gotten it set up for the first time with my Multiamps, in what is now a horizontal bi-amping: each Multiamp is now in Stereo mode, controlling a left and right tweeter and a left and right woofer. The crossover points, which were handled by each Multiamp, are now handled by the DCX. So, what I have done at this point is to use the DCX for my electronic crossover (it will function as a 3-way XO) and now I am using my 2 multiamps in stereo mode. Each multiamp with be used in a horizontal bi-amping mode. Instead of a stereo amp powering 2 apeakers with passive crossovers, I have a Multiamp powering stereo tweeters, and stereo woofers. The signals are sent to the multiamps after the DCX has handled the crossover duties.
THe DCX has 3 inputs (L+R plus an SP/DIF in, as modded) and 6 output channels. Here is the chain, until I get my subs and sub amp:
CD-1 --> ACA preamp --> DCX 2496 --> Multiamp 1 --> tweeters
--> Multiamp 2 --> woofers
After listening tonight, I definitely need to dial down the tweeters since they are more efficient than the woofers. They sound great but are just too much at this outoput level compared to the woofers! This is what I had done on the Multiamps (they allow for that adjustment as well).
Another possible chain with the DCX is to do this:
CD-1 --> DCX 2496 --> Multiamp 1 --> tweeters
--> Multiamp 2 --> woofers
This uses the CD-1 as a transport, bypasses the tube output, and used the DCX's upgraded DAC. This is something I will explore next.
And here is the chain when I get my VMPS subs and Crown K2 amp:
CD-1 --> ACA preamp --> DCX 2496 --> Multiamp 1 --> tweeters | Marble
--> Multiamp 2 --> woofers | 9.0s
--> Crown K2 --> VMPS subs
