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Update on the wine situation. Not great but better than initially feared: https://www.nytimes.com/2017/10/10/business/wineries-california-wildfire.html Another positive -- kids and I tried to sign up to help out at the nearest evacuation center and were turned down because they'd already had such a flood of volunteers that all spots were filled for the next few weeks. Their school PTA is putting together backpacks of toiletries, stationery, stuffed animals, pajamas etc. for kids in the affected areas, so we assembled a couple of those and dropped them off. Classroom was already half full of bags on the first day of the effort -- nice to see.

This makes me happy!

I plan to use HD650 and HD800 with it. It sounds interesting but I think I'll see what Doug can do for me instead.

After swapping out the tubes with better ones (Penta Labs for 12AT7s and Tung-Sol for the 6sn7s, not pictured below) I was able to wipe every single bit of hum. There is still an issue when the volume control is in the 11:00 to 3:00 position where hum comes in, but for now I am just leaving volume at 100% and adjusting from the source. But I now consider this a successful build! The sound is a big leap up from the SRD-7 I was using. Thanks to everyone in the community who helped on this. James Lin for the design, the great article on AudioXpress, and overall thought leadership Kevin Gilmore for the board layout and guidance gepardcv for providing KGBH PSU boards and being so patient as I resolved the exploding zener diode issue! I owe you, man! mwl168 for doing the group buy and for providing endless guidance. congo5 for doing the early prototype build and showing just how good this design is. jose for doing one of the early builds and giving me guidance and most of all, to my son who came up with this project and did most of the soldering after my exploding zener experience!

Thanks, mwl168! I just took all the input wiring out and re-did it using info from your link and other posts, and magically it works!! Volume is smooth and quiet. Yes!!

What TMoney said. I haven't heard the jh16s sound better than with Doug's amp. I am glad I was able to weather the financial storms in the past and didn't have to sell it after all. I enjoy it for a few hours every day in my office.

I have one and really enjoy it. What headphones do you plan on using with it? It has a warm and inviting sound with beautiful soundstage but a little soft around the edge. I also use mine at work. It won't measure up to ECP DSHA-0 or 2 or Justin's GSX-MKII but as an all-in-one solution...a very solid choice. DSD is great on this. You can buy a Sony NW-A35, load up some DSD albums, and output DSD via its WMport to the ZH1ES for native DSD playback. Because of a Hybrid Class D design, digital input will yield the best sound quality. You can also use it as a DAC but a DAC out section is an after thought for this amp. Beautifully crafted with 5 years warranty from Sony. It sounds better than the HDVD-800 driving the HD800.

Well, after all of the adjustments mentioned, and after warming up for about 1 hour, I can say the amp is pretty much silent. My son, who has much better hearing than me, says he can still make out a hum, but it is really not bothersome. If I listen to the SRX-Plus with no music playing, and pull the headphone plug while wearing them, I can barely make out any difference. I am going to try different tubes when they come in this weekend, and see if that makes any difference, but I am a happer camper right now! EDIT: I installed a quad set of Penta Labs 12AT7's and that eliminated the remaining hum. Odd, because it was the output stage tube that I thought was causing the hum because when I swapped the 6SN7GTA's, the hum switched sides. More to come once I install a new set of Tung Sol's tomorrow when they arrive. Now, as to SRD-7 vs SRX-Plus, the winner is the SRX-Plus pretty clearly. Even when driven by a very high quality big $$$ power amp, the SRD-7 has a rather hollow and metalic tone to it compared to the richer, fuller, warmer SRX-Plus. Interestingly, when I put my 507's on the SRD-7 and my son's 407's on the SRX-Plus, the 2 compared pretty well. So the 507s are a similar step up from the 407s as the SRX-Plus is to the SRD-7. I will keep the SRD-7 as a backup, but the SRX-Plus is now my daily driver. One other modification I would like to make is to add a delay relay to the headspeaker output, which keeps open circuit for 10 seconds and then connects the L+ and R+ output lines to the jack. Any idea of where I could source such an item?

There's so much to like there

This band has clearly listened to a LOT of Talk Talk. NTTAWWT.

Need to dig that out. Thanks.

Damn good stuff... Young Marble Giants - Colossal Youth

Tangerine Dream, Quantum Gate

I would go with the DSHA-2 Shelly. It's a a great sounding amp requiring a very small foot print. Still, u will need a DAC to go along with it. As a hybrid digital amp, you will not need a DAC for the Sony. Still a warmer tonal balanced may not work out great with the HD650 but is a great match with the HD800. The Sony amp has enough power to drive any dynamic phones but not quite enough to bring out the best in HEK or hard to drive plannar. The ZH1ES was within a striking distance to Doug's ECP DSHA-2 prototype when I had them side by side but the production DSHA-2 should widen that gap. The bass on the ZH1ES is quite generous but the attack is a little soft. I think Sony had intention of voicing this amp to be as warm and analog-like and I think they do have a very good product at the end of day. A used ZH1ES can be found for as low as $1500 making a really goood deal for a one stop solution.

Stay safe, Cali mates. I wish they control those fires soon.

Agreed. It is a pity. I think the grassroots is in good shape though. Whether that translates into better results up at the top of the pyramid one day -- who knows?

Trump probably had a dry turkey sandwich and made the decision to ban Turkey forever.

Fuck. That is devastating. I'm so sorry guys I learnt that I cannot get US visa any more. I wanted to join you guys in 2018 meetings. I really feel sorry about it. As return we stopped giving visa to USA citizens. That made me laugh. And I got my pre and power amplifiers today: And speakers are on their way:

Hum problems are a b***h. You only need patience. My SRX-P is dead silent now but I needed weeks of work to find the cause of the problem. Basically trial and error. Edit: Laowei put this layout on "Technical Assistance/Advice Thread" maybe It can help you too.

Your hum problem sounds awfully familiar. I posted about this a few weeks ago, see https://www.head-case.org/forums/topic/12840-technical-assistanceadvice-thread/?do=findComment&comment=772776. A few things I have found helpful in eliminating noise: 1. Do not attach volume pot grounds to anything. Makes things horrible. 2. Attach input XLR pin 1s to the chassis near the input. Many Neutrik jacks have a special pin or other feature to do this painlessly. (Check continuity to be sure.) Do not run grounds from the XLR inputs anywhere else. If you have loop-out XLRs, also tie their pin 1s to the chassis. 3. The safety earth should be separate from the star ground, and needs to use tooth washers and locking nuts, since it's the critical electrical safety feature. I have found that it does need to be tied to the star ground. 4. Do not allow any audio signal wires in any direction to run close to the transformer. 5. Do not allow any AC wires from the transformer (including heaters) to touch any signal wires. 6. With the mini-BH PSU, you may hear some hum with no input plugged in and the volume control turned up. I've empirically found that the mini-BH PSU hums in this situation and the GRHV does not. There should be no hum with a source plugged in, for any position on the volume pot. Note that in my builds, I attach the amp boards to the PSU, rather than to the star ground. I have found it to makes no audible difference with amps using the mini-BH, GRHV, or GRLV PSUs (i.e., dead silence). YMMV.

I have not cased up my SRX Plus yet but in its air-chassis mode it is dead silent when I am carful with the wiring arrangement. I did experience tube-related noise at different time; once with a noisy 12AT7 and once was actually caused by dirty tube pins on a 12AT7 that just needed to be cleaned. Maybe try cleaning the pins on the 6SN7GTA in question and see if it helps.

Yes, I guess that on eBay you can find some PCB, but I only use a KBPC5010 bridge diode with a R10 as Nelson Pass recomends. My ground way : Psu Ground to Star grounding (before Bridge diode) Amp Ground (Amp has G on LV and HV, really is the same plane so I only use one of them) to Star grounding (before Bridge diode) or PSU Ground. Input rca (insulate)/XLR to Volume Pot Volume Pot (insulate) to Amp. Star grounding (diode/resistor/cap) to chasis Transformer shield wire to chasis (On the same place where you put the star Grounding) Earth ground (plug) to chasis. (On the same place where you put the star Grounding) Very important: If you are using an unbalanced input, you must bring the "cold" channel to ground.

Sorry, English is not my language. If you take a look at my photos, you can see that I separated as possible the heating lead to the rest. I did a star grounding with a simple loop breaker (with a bridge diode) I'm sure that you know this but I recommend you read this http://sound.whsites.net/earthing.htm

If it can help you; I had similar problems with 6 step and a f@$k Hum. I changed the ecc81 quads until I found a perfect mach quad at the same time, I separated the AC lines and did a ground loop breaker. Now my amp is absolutely silent and the different between triodes is around 3~8 volt.

Could be a couple of things going on. First of all, what are your input stage plate resistors? That plus the input tail current source sets the plate voltages. If your B+ is around +370 volts, and you have 250k plate resistors, you need the tail current source to be running at 2 x 185/250k = 1.48 mA. If you are running 300k plate resistors, then the tail current source should be 2 x 185/300k = 1.23 mA. If B+ is at +340 volts, you want the upper plate voltage to be at 170 volts, which means the tail current source should be 2 x 170/250k = 1.36 mA for 250k resistors, and so on. Once you have set the tail current source to the proper value, you should have the plate voltages close to the desired value. If you are not able to balance the tubes, you need to either swap tubes around until you can achieve balance, or replace the tubes. Not sure about the source of the hum, but if the tubes are bad that is a possibility so I would try replacing them. Otherwise, there could be a ground loop, and those can be a b***h to track down. You should begin by checking your grounds - the amp board should go to a star ground, as should the PS board. Sometimes hum can come from the power cord ground, in which case lifting it from ground with a 10-100 ohm resistor can help. I seem to recall someone posting a diagram for the KGSSHV showing how to connect all the grounds, inputs and outputs, but I can't find it at the moment. I am working on an update to the shunt regulator so I wouldn't recommend building it at this point. The KGBH PS board is well sorted out and works fine.

For the last 35+ years, I've loved Tom Petty's music. When I first heard "You Got Lucky" on the radio and immediately set out figuring out who it was. In the early 80s, the only members of my family who had cable TV were my grandparents. They had MTV, which was a new and gee whiz thing. They also disapproved of me watching it: "it'll rot your brain." I had to sneak in my viewings, and I was lucky enough to see the video for You Got Lucky. I was too young to understand the Mad Max references. I just knew I liked the song and Tom knocked over an arcade game. Several years later I got my first cassette player, and I bought Long After Dark and Damn the Torpedoes ("Refugee" was another favorite of mine.) As my musical tastes evolved and changed from metal to techno to ambient, I have always revisited Tom's music and loved it.

With top Thanks. I buy my boxes in MODU and then I do the mechanised ones myself with the help of a drill, Dremel and a lot of patience. That's why my boxes have simple designs and are so similar. I admire the cases that make other members much more elaborate than mine but with my tools and skills I can't do much more.

Still v. smoky here. Probably not all pot byproduct.

Sad that you can't get a visa Ozgur. That it's due to a policy that will accomplish little or nothing makes me more sad.