CLSII potential newer buyer

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Hello Woof

Let me tell you. Using these Melos was sometimes a nightmare. First. I had to draw the schematics because nobody has them in the world. The output sockets develop bad contacts so I had to change them. The circuit board heat so much so it blackened in some places. This means conductive carbon. With near 600 VDC on some board traces, I had arcing and redesigned the way high voltage goes to the tubes with teflon wires, repositioning fuses etc. These amps like most Melos gear had reliability problems and technical design which needed work to work correctly. Mark Porzolli, the designer of Melos gear was sick about using mosfet buffers between each tube stage. I stripped some and it helped a lot for the sound. Leaving for one weekend, I forgot to turn off y amps. When returning at home, I opened the house door an smelled a strong burnt odor. One amp was not working and had an OPT toasted !!!. Arcing again was the culprit before I decided to do the BIG job. I discovered the OPT in these amps are in reality push pull OPTs connected in single ended mode !!! Square waves in the bass was not good and guess why ?. A friend of mine had a monster pair od Audionote PP OPTs with 1.8 K primary. This is what I needed. They had exactly the same size and mounting bolts as the originals. As They were still PP OPTs, I saw in Glass Audio an article from Dave wolze wo made SE opt with PP big Hammonds OPTs. He used a hacksaw and made two gaps (cuts) in the armature to convert PP OPTs to SE OPTs. As I didn't had the patience to take 3 hours to do that per transformer, One of my friends did them with a band saw. I finished them by hand to take care of internal copper bobbin. Now, how it sounds ? MARVELLOUS, New amps, incredible, I saved my amps and they are hard to beat with good speakers. It is shame because many Melos gear is going in the garbage because nobody can repair them. I really thought being alone to use these SE-75, More about these amps driving .... the CLSII.

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Oh, what a wonderful project you embarked on. Yes! Those Melos amps were a pain in the butt to get going without hassles. On certain days they operate fine and on other days they crap out. I can't even remember the number of times we sent these monoblocks to our techie to fix. Once we received all the required parts through our distributor in Thailand, our techie was able to get these beautiful amps going and wow did they really shine!

As you correctly pointed out, once upto proper spec and in top working conditions, these particular amplifiers are SOTA!

Sadly many can't do work like this anymore or many techies aren't bothered because it takes a lot of time and effort. You'd have to take annual leave just to service these things. I had the Golden Triode version, I think it was called Gold 400's or something like that. They were Melos top of the line.

These days, very few companies offer tube gear like this, only a handful can compare. CJ, VAC, VTL, Destination Audio, Aries Cerat and Audio Note Ongaku or the Kogaru monoblocks are on par. That's the class of tube gear these amps are in. I guess it's like one of those rare thoroughbreds... on certain days they don't run but when they do decide to run, get ready for blistering speed!

Woof! RJ
After many hours (or days) working on these beasts, they never broke. I bought a 6P45S batch to be sure I could be safe for years. Presently, I drive speakers which have 91 db/1W/1M with them. I always have a really low residual hum. Did you have this problem ? If you ever see parts for these amps and other Melos amps, I'm buyer. Here are the original stock 20 kHz square waves and 20 kHz with new OPT and circuit mods. This speaks by itself. SQ 20K original.jpg20 Khz.jpg
With the Melos amps, there was always something to hold our breath... either a static problem when the warm-up circuit was engaged or that annoying hum even afterwards. On difficult loads and low efficiency speakers, like Apogee's, Maggie's or older ML stats, this hum wasn't that noticeable but it was there. However, on horns (ex. Avant Garde's) that hum was amplified 10 times!

It was only after we contacted Melos directly and obtained the required parts through our nearest importer, that set the ball rolling towards a hassle free trip having to ship these amps back & forth. They performed much better but when one of our customers was quite keen on them, I passed them along to make way for CJ's Premier 8A monoblocks, top of the line at the time. The CJ gear was much easier to work with, and an absolute joy to own. Never looked back since 98 onwards.

Nonetheless, those Melos amps were of a unique signature sound, such that it wasn't too colored, allowed more of the recording to pass through in a more neutral way. Actually thinking about it, that was probably the most significant difference between all the others owned (ARC, VTL, Manley Labs and Sonic Frontiers). If we wanted a very honest and close accuracy in recording playback, this is where the Melos amps proved to be tops!

Hope it all goes well, certainly looks like you're on track.
Cheers, RJ
I have an original pair of CLS’s that I drove with a Melos amp for years, noting that the first two amps were returned because of failure. I eventually ended up with a Melos High Power amp that sounded great and served me well for years. Eventually, even that amp started giving me issues and, given that it is difficult to source tubes for it, I eventually ended up with a Sanders Amp. Of all the SS amps that I tried, that is the only one that properly drives the capacitive loads of the CLS’s. I’d still like to get some tubes in the chain and at some point I will try a few tube preamps. FWIW: Harry Pearson thought the CLS/Melos Amp combo was divine.
Output tubes for the Melos are still easy to find if you buy Russian 6P45S military tubes. There are Ukrenian sellers on eBay. I can attest Svetlana, OTK sounds good and are rugged tubes. Ham radio peoples still use 6KG6/EL519/EL509/6P45S so that's why they could be hard to find someday.
Thanks for the suggestion on the 6P45S tubes. I need to figure out if i have a bad tube or something more sinister going on with the Amp. Will do that some cold winter day to come.
One of the biggest problem with these amps is bad contacts with output tube sockets. If you ever buy 6P45S, carefully clean the pins. These tubes are NOS (new old stock) and pins are often badly corroded,
CLSII's are fantastic. Picked up mine from @Lightloopy on the forum here and have been thrilled with them. I do run two ML Dynamo's with them for an extra kick. Currently feeding them with McIntosh MC257 Power Amp.
Glad to hear you are enjoying them! Must sound great with the Dynamo's. Beautiful and unique speaker.