Victor Chew

"Just get a SRD7 for the same price...plus it comes with 2 authentic Stax jacks" Agreed.

I got the DUOYI 294. Did sampling only and they seem fine so I assumed they were all ok. I guess everyone has to be tested in future. Bought it from the same fellow but the second batch are all fakes. I will go to the shop next week and show it to them. Bought it from them because of long and good previous relationship and wanted to sgupport them where possibe.

On close examination of the FQPF8N80C realised that 2 looked different. On the +ve HV side which works fine uses the same ones as in my perfectly working on board version. Fakes, I believe brought the -ve HV rails down. Bought them from my local electronic store. Should have looked closer before puttng them to work. In anycase, will have to get them replaced.

Started building my off board. PSU -ve HV side blew up sending parts of one FQPF8N80C flying around. LV and the +ve HV is fine with nice readings. Checked for shorts but don't see any so far. Took down the other FPF8N80C, 2N3904 and diode 24v with it. 20K resistor slightly blackened but tested ok. Trouble shooting now.

Am I correct to guess that the costs estimate for this build excluding chasis, volume pot, input jacks and tubes should be no more than US500 to US600? I believe the PSU should costs more? Costs of tubes is where the numbers will fluctuate greatly correct? Any default tube type or manufacturer recommended?

I believe T-Money has a working one too. Kerry was on it, but not sure if its completed. He wanted to increase the current.

Did some googling and this is what was said - EL34 and 6CA7 are similar. Both, are interchangeable without circuit mods. EL34 are British and the other American. Some have said that the EL34 sounds warmer whilst the 6CA7 harder with more top and bottom. Does this mean that we can use EL34 as an option as well?

Would it be appropriate to have a dedicated thread for this megatron amp once a name is chosen?

I believe he is now out of them for sale, with a few left for his own use. Besides, this looks like a mega amp with exceedingly high level of performance which deserves the "best" attenuators. Not saying that the Alpha is not good but this just deserves the top notch.

Any name for it yet?

Looks very exciting. Will the 6ca7 have to be matched given that it is a parallel pp? Any chance the attenuator can be incorporated into the circuit to reduce the amount of floating wires?

Will this measure up in performance against the T2 and the BHSE? It has has more power than the KGSShv, with lower voltage swing but more current? This is tempting to build. Less worries with fake semiconductor parts, at least for the amp part.

Very nice John, its already very nice as it is. Congratulations El_Doug.

Congratulations! I am so happy for you. You have come a long way eggil ..... Now enjoy your music:). . As I said, sometimes "the harder something to achieve, the sweeter the victory".

Quite a bit of disussions in various directions until the design is finalised, so not surprisingly, confusions can be caused. However thats just normal. Thats a nice build Birgir. How does it perform?

The harder something is to attain, the sweeter the victory:).

Bias ought to be 580v instead of 480v. A need to use at least 3A fuse for the PS alone looks like it is pulling quite a lot of current. I am using a 2A with amp connected to the PS and source playing through the amps. Nevertheless, congratulations on get the PS up.

No worries, them I guess, as an option, we could thread it ourselves. Could I have 4 jacks please? What is the height of the round stax portion please?

Will the screw holes be threaded for the M3 screws? Just incase the front plates are thin.

How are you measuring them eggil? I believe 2 wafers control one channel (either right or left). Each XLR channel has hot and cold. Hot to one wafer and cold to the other wafer. One wafer will have "in", "out" and "ground". "In" will connected to the XLR and "out" to amp input. To check if the wafer/attenuator is working correctly measure the "in" and "out".

I followed the instruction here - http://www.diamondstar.de/transistor_matching_jfet.html

Got a bunch of J74BL from my local shop and have been matching them. IDSS readings are between 13mA to 20mA. These are too high and are obviously fakes. Also got a bunch of K170BL and the IDSS is between 3mA to 5mA. The spec sheet says 6mA to 12mA for the BL and 3mA to 6mA for the GR, These are obviously not BL grade, and may be GR grade badged as BL.

Awsome! Real hand made stuff. Vanishing trade. Everything is made by machine these days. In the good old days when things were made with the hands it has, to me, a soul. Which is why stuff made, the DIY people, is so different from the commercially made items. It has our heart and soul .

Thanks Kevin. Thanks Marc.

John, what size volume knob is yours cut for. If its something like mine you are looking for I should be able to help. I have got a spare lying around somewhere. Anyone got 2 spare DRV134 boards? I am thinking of incorporating this into the build so that when the RCA comes in it will be is turned to fully balanced just before it "hits" the balanced boards. I am aware of the DC offset problems but still willing to give this a shot. Might be postinging this in the wrong place and will remove if necessary.