Mullet

Ok... I think I figured it out. I used Belden cable for my hookup wiring and it looks like ground and left channel were touching because a dodgy stripping job. So chalk it up to faulty cabling. Phew!

I initially noticed issue when both channels were out of balance. I first looked at the hp jack because I noticed it wasn't isolated from chassis ground. I've since fixed that issue. Then the sound got better. Both channels balanced with same apparent level, but with the lack of bass and what seems like a really wide stereo image. Wider than expected. It could be a phase issue. Would a grounding issue show up as phase problems? What's interesting is that it's only in the bass region. Connectivity looks correct. I've toned everything out with a DMM. So I don't think I have anything backwards. IN1 is my left channel and IN2 is my right channel. Same goes for outputs. Other things to note: I did have signal ground connected to the chassis then through a ground loop breaker. I haven't been getting hum so I've removed the GLB. Same issue. Using the GLB, It made the chassis share the same ground as signal ground. Not sure I'd want this... maybe I do? I also originally only had OUT1, OUT2, and one of the GND paths going to my HP jack. I've since added the the 2nd GND path. No dice. Sounds the same. I did buy 2N5564 on eBay. I know I prolly shouldn't have. Could poorly spec'd or fake 2N5564 create a situation where the bass is so rolled off? FInally, trying different headphones didn't make much of a difference. I mean they sound different, but don't have bass. I'm going to try a full rewire on the outputs to see if that makes a difference, but may look at replacing the 2N5564 next.

I recently finished my Krell KSA-5 Klone. I'm having something weird that I can't quite wrap my head around. When listening to music there is a lack of bass. It just seems to be sucked out. I swap the same HD800S headphones into another amp and voila bass is there on any given track. I don't hear any distortion or a buzz or anything that would be akin to a ground loop. Anyone ever heard of this kind of phenomenon with this amp?

Do you mean that the voltage across the test points will constantly change? In my case I set the voltage to 125mV via pot after the amp has been warmed up. It drifts a little but doesn't stay exactly at 125mV. Or do you mean the dc offset with OPA445 removed? This is who I bought 2n5564 from... https://www.ebay.com/itm/1PCS-New-2N5564-CAN-6-Matched-N-Channel-JFET-Pairs/392370230460?hash=item5b5b1694bc:g:wDEAAOSwvFNdSPV7

I'm no expert, but I'd just use the suggested parts. You're thinking of using these instead of LSK389 or 2N5564? I know this is generally not advised, but I got the 2N5564 on eBay from seller Top Chips. I've recently fully powered up and tested the amp prior to casing things up and the amp plays music. So the parts are legit? I have no way of telling. My guess is the amp wouldn't work at all if the parts were fake. On another note, you do have to watch out with eBay - I tried to skimp on paying $12 x4 for the OPA445 and bought them on eBay. When trying them out in the PSU no voltage or close to none. I ended up having to go to Mouser with my tail between my legs and bought 'em there. Boom success!

Thanks!

Quick question when matching transistors... on same channel - L or R... do you match PNP to NPN with similar or same HFE? or do you match NPN to NPN or PNP to PNP?

For the alternate power supply shown a few posts above, what hardware is requiered for the TO-3 transistors? I'm looking at kits on eBay and they come with more parts than I think I'd need. I'm thinking all that is needed is: 2x plastic washers, 2x screws, and 2x nuts. The kits come with 2 sets of metal washers and a metal tab for soldering. I'm thinking I wouldn't need these extra parts. See attached picture.

So I ended up figuring out what my hum issue was after moving trafo orientation. BTW this is for an EHHA Rev A. It turns out that my RK27 was going bad. After readjusting everything, I noticed that I was still getting leakage even though my pot was fully turned down. I could hear a small amount of audio coming through. I replaced the pot and now we're back in business. With regard to my Klone, are those silicone / mica insulator kits for all the F15030/1 parts required? I'm counting 10 on the main amp board and possibly 2 on the alt. psu board.

Interesting. So basically turn the transformer until it's facing a different direction and thus reducing the hum. In this case it seems there is a possibility of having to permanently extend wires to get enough length.

Not on this particular amp. But I do have it on another amp and I was thinking of taking precautionary measures on this one. I'm thinking of going single chassis.

Thanks! Anyone have experience with these iron transformer covers from eBay? Do they really work? I'm thinking of using one in my Klone. https://www.ebay.com/itm/1pcs-toroidal-transformer-circular-cover-the-105-51mm-balck-metal-Metal/264373072892

I'm finally about to build my KSA-5 Klone. I shelved the boards for like 5 years - can't believe I waited that long. Thus far with eBay and a cart full of goodies from Mouser I've gotten the price down to a reasonable ≈$215 including I/O jacks, standoffs, etc. The kits offered on eBay are cheaper. I've been tempted to buy the kits, but fear the parts are cheap and cheerful. After reading through most of the thread... a question or two... For the 2Ω resistors - can I use this? - 667-ERX-3SJ2R0 Or are 1% resistors necessary throughout amp? Thx, Mullet

Just figured I'd spread the good word... http://tinyurl.com/luoq6cj If you know of any vendors that might be interested or you are a vendor that is interested in participating please PM me.

Nope no ferrites. I have tried installing them to no avail. So I put the jumpers back in place. So basically only thing that doesn't check out is the "no reading" on pins 1 to 3 on U3. I'll try re-flowing those joints. So are you saying that 1 to 3 should be slightly higher than 8 to 3? Does U1 look right? Here are some pics for posterity...