The end of an era.
I’ve owned my VTL 225 MonoBlocks for almost 30 yrs.
Over the last year they have been blowing tubes and shorting out at an unacceptable rate. They have no soft start capability which stresses the circuit and tubes at startup.
The 525 Volt rail doesn’t help. I actually had an internal fire which torched some resistors.
It was time for a change.
Being a fervent ModWright fan, I decided to call Dan Wright for some advice.
I own a tube modified Pioneer CD player and a tube preamp made by him.
He has always been a believer of using tubes for the front end while using a Solid State Amp for the back end.
Since he knew I was an avid Tube fan he suggested that a Mosfet SS Amp would be a good choice as they tend to be a tad more gentle in nature soundwise.
He had a demo of a KWA 100SE which he would let go at a great price.
Roughly 100 Watts into 8 ohms and 200 Watts into 4 ohms.
Since my Hales Signature Twos are 4 ohms with a sensitivity of 90dB, I figured this would be a fine match. (Especially since I utilize 3 powered subwoofers)
Normally I would have to audition a product before committing to a purchase but I have grown to trust Dan over the years from a design and integrity POV.
So I went for it and received it about a month ago.
Dan suggested that it should be burned in for around 450 hrs (actually less because it was a demo).
So for the past few weeks I’ve been trying to get the sound I want by using various tweaks. Due to the nature of the Transformer design and input circuit the Amp cannot be floated.
It must use the hot, return and ground. Therefore, it has become the single point ground for my system with all other components floating. (otherwise I get ground loops and hum)
The sound of this Amp was quite different than the VTL and I wasn’t sure I could accept the differences at first.
I knew from the outset that the midrange of the VTL could not be duplicated as that is the main strength of a good tube amp.
The KWA 100’s midrange was detailed, crisp and had body. It was slightly lacking (I thought) in it’s harmonic content. (odd vs even order stuff).
The VTL was stomped in the treble presentation by the SS Amp (again, expected).
The bass was pretty close but the KWA 100 won out due to it’s precise rendering of pitch. No one note bass here. All the slightly different, fast paced notes were clearly differentiated from each other. Plus the bass was a little tighter.
The dynamics and transient responses were identical. Both great.
So, apparently, the main bugaboo was the KWA’s midrange.
I utilized every tweak in my arsenal to try and get that midrange “bloom” common with tube amps. Mostly power input tweaks using filters, parallel capacitance and various Quantum Products. I sweetened the midrange quite a bit and got a tad more bloom.
Over the past few weeks, by playing cuts I was really familiar with, I came to realize how euphonic my VTL was in the midrange. It wasn’t entirely accurate but was sure pleasant to listen to.
So at the moment, I’ve come to appreciate the more accurate rendition of my KWA amp and am quite pleased with it. The sound appears to be evolving with additional break in hrs for the better. After I feel it has run it’s break in course, there’s a possibility for some tube rolling in the front end to give me a touch more second order stuff.
I have a dream to try the legendary Bendix 6900 tube in my Pre Amp. Although it may not help in the Bloom Dept.
Right now, the KWA uses a single input transformer. I suggested to Dan that an additional one could be added for channel separation and perhaps a partitioning within the amp isolating the two channels. What do you think Dan?