paul79 Posted April 16, 2014 Share Posted April 16, 2014 (edited) I'll +1 to post #20. He also offers a single chassis stereo version. Quietest amps I have ever had here. Edited April 16, 2014 by paul79 Quote Link to comment Share on other sites More sharing options...
gfinlayson Posted August 27, 2014 Share Posted August 27, 2014 (edited) I'm a little late to the party with this discussion, but thought I would chime in. I own the slightly older DK Design VS1 Signature MkIII amp, which was replaced by the LSA Signature. Cosmetically, they're slightly different, but under the hood it's the same amp. The LSA amps come in three varieties, Reference, Signature and Statement. The Reference is the entry level model. The Signature has several mods - addition of an 'active tube-load circuit', upgrade of the signal path caps in the preamp section to Auricaps, upgrade of selected resistors in preamp section from carbon film to metal film, upgraded wiring from amp section to speaker terminals, and hand soldering of speaker terminals vs terminal blocks. The Statement takes things to a whole new level - Signature upgrades plus, upgrade of coupling caps between pre and power sections, additional transformer to achieve dual mono operation in the preamp section, changed configuration of large toroid transformers to achieve dual mono operation in the amplifier section, add proprietary circuit to achieve seperate voltage regulation of input and driver stages of the amplifier section, upgrade amplifier feedback loop parts. I've owned my Signature for 5 years and wouldn't part with it, period...... Well maybe, if someone were to offer me a Statement instead...... I love the sound of it. It's transparent, neutral, natural sounding, detailed but not edgy and can drive the most difficult of speaker loads. Rated output is >150W pc into 8 ohms, although that's not the whole story. When Stereophile bench tested it, 205W pc into 8 ohms was reached before it clipped, it'll output >300W pc into 4 ohms and ~500W pc into 2 ohms. It weighs in at just shy of 90 lbs, it's built like the proverbial tank and no matter how hard you push it, the heatsinks barely get warm. I've not heard the Statement, but from the reviews and what LSA says about the differences, I'm seriously considering my options to take my Signature up to Statement trim. Support-wise, LSA has been outstanding. I recently replaced the tubes in mine after the RH channel tube failed. I e-mailed LSA about whether the tubes would need to be re-biased and was advised by LSA President, Brian Warford 1) to replace the trimmer pots for biasing the tubes from the existing pots to multi-turn cermet pots and 2) supplied with detailed instructions and photographs showing how to change the pots and how to bias the tubes properly. I went back to Brian with a couple of other queries and was supplied with more info and full schematics for the amp. Replacing the pots took 10 minutes (I'm not shy of using a soldering iron, though) and biasing the tubes was pretty easy using a multi-meter, a couple of 8R2 10W wire wound resistors and of all things an Android signal generator app for my phone! The amp sounds better than ever now. The stock Electroharmonix 6922 tubes can be changed for a variety of different options and LSA positively encourage tube rolling to find what suits your personal taste. Here's a few photos of my Mark III..... Under her skirt Active tube load circuits by the preamp valves Quite a purposeful look 3 pairs of output transistors per channel - Darlington pair SAP15 transistors are rated for 15A collector current each, probably serious overkill...... Edited August 28, 2014 by gfinlayson Quote Link to comment Share on other sites More sharing options...
Kent T Posted September 4, 2014 Share Posted September 4, 2014 I will say I like the old LSA Standard amplifier a great deal. A friend who is a HiFi dealer has one on the showroom floor. Very musical sounding and lots of power. Quote Link to comment Share on other sites More sharing options...
Gary Price Posted June 23, 2023 Share Posted June 23, 2023 Its been awhile since these posts were made regarding the LSA Hybrid Amplifiers. I have the Statement version and have been searching for Schematics . I have an issue with a channel cutting out and have never had any luck finding the Schematics. Hoping some day I will find them. There must be some out there somewhere. Quote Link to comment Share on other sites More sharing options...
RandomAudioGuy Posted September 2, 2023 Share Posted September 2, 2023 Sorry to dig up this very old thread, but I too am looking for information and schematics on the LSA Integrated Amplifier (Signature). I inherited one recently and there is a loud hiss when it's on with no signal. The amp works, but the hiss is about 50% of the sound regardless of where the volume is at. I believe it's time to replace the tubes. I have contacted Underwood Hifi and the local previous local importer here and neither could provide any assistance. I'm hoping I can find some instructions on how to do this. 1 Quote Link to comment Share on other sites More sharing options...
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