joehpj

470VAC is even way too high for 500V. Where did you get your trafo?

http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=577DCA0C77 This is GG BOM I made for one board. Please check. Please note: Need 1 pair of 2sk170 or LSK389, which is NOT included in BOM. grid resistor changed from 470R to 10K. I asked Kevin he replied there shouldn't be difference and higher value would be safer when the tubes fail. (T2 use 22K) servo op changed from op27 to TL081 simply because latter is cheaper. mounting kit, IC socket,pins, tube socket NOT included. Zener changed to 18V.

Since it's adjustable, how much current will you recommend for the balance of performance and lifetime?

Is there any update on GG boards? There's only one version on KG's server, so I assume it's the final production version?

This: https://item.taobao.com/item.htm?spm=a1z09.2.0.0.TlWodm&id=534403663171&_u=a1t9atf5ae38 I ordered two. I will take pictures and report back when I get them.

Thanks. I had a plan to build a GG before I knew the problem of frequency response congo5 met. It's time to restart the project. One more question. What's the influence if I increase/ decrease the value of the resistors connecting the tube's G1 to G2 and G4 to G5? I had read from somewhere I could not remember which said the value of the resistors needed by EL34 and 6CA7 were different because of the internal structure difference between beam-tetrode and pentode. Edit: and outout resistors? Should I just copy the settings of T2?

what was @congo5 building? I thought it was GG not GG DHT?

unbalanced input only?

IMHO, Bryston is not best but a least not crap speaking of sound quality. So, what's the problem? (serious)

only $37950. nice!

When will the chinese amp arrive?

would like to know comparison between 007 and l700

I like that bullet-shape feet. Do you have a link?

When I was laying on my bed, one thought suddenly came to my mind: the difference of 007 MK2.5 and MK2.9 may because of the cable. Since PCOCC has been discontinued for some years(3?), Stax maybe had to change the material of the cable as the original PCOCC cable was run out of. Hmm, who knows?

I use washer that has sleeve longer than tab thickness. And I enlarged the hole on the thermopad to make sure the sleeve was inserted into the pad. I suspect if the sleeve length is equal to the tab thickness, the tolerance of parts may make it prone to arch. Both washer and pad come from china, not mouser parts. Two builds (KGST, carbon) now, no problem. For forward and harsh of carbon, after burning for 4hrs/day, 2 weeks, it improved quite a bit. The sound character now is really like a puncher KGST. Mid and tremble are nearly equal. Soundstage are wider. It sounds like to have more headroom and control if turning the volume super high. But I usually listen to lower volume though.

No this is wrong for megatron. At least no lsk389 is needed

For the 4 tubes, is there really benefit to go unregulated PS or even regulated PS? Because I wanted to do two-box design and buckle the heater wire with others to use a single connector. I suspect AC 60hz noise will affect others. Heater for el34 needs 6.3V/1.5A each. So I will aim for about 10A for the PS. Also, the heaters are sitting at -450V, so the PS should be floated? I wanted to go tiny and simple. For single regulator, I could only find MIC29712WT, which is only 7.5A max.

I still need some more days for detailed description. I've only build a KGST and this is the second one. Never heard a SS/SShv, so neither can I compare with . Sound wise both sounds pretty alike. Carbon is more dynamic and.......brutal. Bass is better than ST. It's puncher and tighter. I think it benefits from the new CCS. My ST build only has single 10M90S. But ST has warmer mid range makes it better for presenting vocal recordings. (2nd distortion?) Carbon is more sensitive to front end and has lower tolerance to bad recordings. Bad recordings played with carbon were harsh. Maybe it's due to the lower distortion and higher output. My HP is modded 007A mk2.9. A friend of mine build SShv/ST/Carbon told me Carbon has best overall performance. 400V@20mA. Measured about +-402V after warmed up. The pass transistors of GRHV are not hot. So the amps can use a large portion of the sink. All pass transistors including LV are off board, so there's no sink in the case and makes the temp in the case lower. And also the junctions of the case are tight so every plate of the case works as sink,too.

current is 20mA Temp is lower than I expected. Room temp is about 25-27 and I can put my hand on the sink by just feeling a little bit hot after 2 turning on for 3 hours. I think the huge sink did a good job. size:12.5*31*5cm, the base is 1cm thick. And I lift the whole chassis up by using high screw-type feet. (4cm)

Sorry, the link was wrong. It shows 0 items Taobao seller drilled the hole for me. It's a Chinese sealed 23 stepped VR. Overall quality was good, no issue with sound. This is the second one I brought, but the rotation is tighter this time. Recommended. https://item.taobao.com/item.htm?spm=a312a.7700824.w4002-1004073654.21.nkSptS&id=522043952195

It's alive!

drives directly? transformer?

No, never really democracy. During 1911 to 1949 the whole china was almost in civil war and war against Japan. And yeah, back to topic.

what's the el34 you are using?

Copied means you are good. You really can't stop people doing reverse-engineering. There are all kinds of copies all over the world not limited to Taobao. B22, Dartzeel, HA5000, Rudistor, ML amps.... The best copy of Dartzeel was even a 1:1 pcb copy, because they bought a brand new one to rip apart. So, my point is, if there's market, there's copy. It's simply different market for those who bought a genuine Dartzeel or a copied one. I for one hate copy cat but there's really nothing we can do. (at least now)