OK lets take this in a little different direction here. Anand I have a question for you about your amps. I see you use a gainclone and a class D. I am going to build my first gainclone here in the next few weeks/months? I am going to build a dual mono design around the 3886 chip. My question for you is about how much power does your chip amp put out per channel and how do you like it with the Abbeys? Also if you can describe the differences between the chip amp and the class D amp I would appreciate it. Now I have ordered the kit for the amp and power supply but am holding off on the transformers for now. I noticed you went for the Lundahl transformers can you explain what it was that made you decide to go with those over say the transformers I can get at parts express for about half the cost. I am not opposed to spending the extra coin if the results are worth it, I just want to hear the advantages from someone who owns and uses them.
Dan
Lots of questions but I will try to answer them one by one.
My gainclones are based on the LM3875 chip, and they are dual mono in build with 2 toroidal transformers from Plitron. They put out about 40 watts/8 ohms and 100 watts instantaneous. They will blow me out of the room with GedLee Abbeys.
My review on the Class D amp (original design, not my latest build) is right
here. The primary difference\ is that the Class D amp image outlines are sharper, the soundstage is deeper,tonality is smooth while being extended on top. Overall at least a 20% improvement over my gainclone for less coin. My gainclone with the diyenclosures chassis cost me about $700 to build. My Class D as posted on the Lab forum cost me about $550.
The input transformer on the gainclone was an attempt by me to make the unit like the
Gill Audio Lissa which uses a Lundahl input transformer. After consultation with Kevin Carter, the U.S. Lundahl distributor, he gave me the thumbs up and I went ahead with the design. I have found Lundahl input transformers to be very transparent and have also tried Jensen in this application. The Lundahls were superior in my honest opinion. I've also used Magnequest, Electraprint, One-Electron, and O-Netics, and of course Lundahl however NOT in this application (in tube amps - they are all quite good actually!). The Lundahl input transformer provides galvanic isolation, a balanced/differential input and the ability to have 1:1 or 2:1 step down ratios, making the overall gain of the amp variable from 24dB or 30dB.
With the Class D SDS254 design, we have a differential input stage designed by Bill Whitlock (designer of Jensen transformers) and a variable input gain from 18dB to 32dB, so no input transformers are needed obviously.
I hope that helps. I enjoy them both, but the SDS254 is more transparent and a better value since it is a cheaper build. It's my reference to compare with solid state amps < $1K and beyond. Any amp that comes through here must have at least the fidelity of the SDS254 to pass for high end. Or else it's out!
Anand.
