Ah, ok. My assumption was that you would use the SimpleSE board.pukka said:
ECC81 is a twin triode, and 5842 is a single triode which means you need 2 of these, but then there is only one 9-pin on board. It is going to be a lot of fun to run wires off the board onto 2 external 9-pin sockets. Or, you are doing wire-2-wire which gives a lot more freedom.
pukka said:
I would just suggest building it as designed. This really is a great amp. The ECC81 works fine. For what it is worth, I have tried some GE NOS, Mullard and JJ ECC81/12AT7 and really could not tell the difference. Biggest difference was with output valves. EL34 more detailed midrange and KT88 better bass. I would send Edcor a brief email asking about the GXSE transformers. Someone has mentioned that it may have more leakage inductance to give guitar sound. I am not sure if that was an assumption, or solid knowledge. I am pretty sure that a member on this forum asked Edcor and they gave the information that they had not built the GXSE for distortion, but that it was beefier than the XSE series so that it could extend from 70Hz (the XSE) to 40Hz. If I were to build another one and was looking for good value output iron (as compared to the best quality at whatever price), then I would probably pick the GXSE15-8-5K.
Chris
pchw said:
Ouuuuch!!!! no way...yes, I'll use tubelab's PCB. didn't know it was a single triode. Thanks for clearing that!
chrish said:
I see, I'll use a JJ12AT7 then.
I'll get EH KT88 after reading tubelab's reviews... blue glow is a plus
Ouch... decisions, decisions... XSE is the known one, GXSE the yet to know theoretical better one.
You have both and can compare, that will clear things a lot!!!
Crystal clear, harshness free medium & highs is essential for me, I can't stand the minimum graininess in that area...
Hi Juanjo, thanks for the offer!!! your profile settings prevent me from PM'ing you...
I asked Edcor directly. This was the answer:
Edcor:
I'm tempted to buy both sets and if GXSE aren't up to the task use them in guitar amps, but right now I'm broken and need to slow down, you know, you start to experiment and everything snowballs, and you end up spending much more than needed, it happened to me in the past
My target is to build the best SE for the money and I believe I can build 2 for less than 250€ each. Hehe, that's less than some OPTs cost!!!
your profile settings prevent me from PM'ing you...I asked Edcor directly. This was the answer:
Edcor:
I'm tempted to buy both sets and if GXSE aren't up to the task use them in guitar amps, but right now I'm broken and need to slow down, you know, you start to experiment and everything snowballs, and you end up spending much more than needed, it happened to me in the past
My target is to build the best SE for the money and I believe I can build 2 for less than 250€ each. Hehe, that's less than some OPTs cost!!!
pukka said:
Ouuuuch!!!! no way...yes, I'll use tubelab's PCB. didn't know it was a single triode. Thanks for clearing that!
I see, I'll use a JJ12AT7 then.
I'll get EH KT88 after reading tubelab's reviews... blue glow is a plus
Ouch... decisions, decisions... XSE is the known one, GXSE the yet to know theoretical better one.
You have both and can compare, that will clear things a lot!!!
Crystal clear, harshness free medium & highs is essential for me, I can't stand the minimum graininess in that area...
If you want clear mids and highs, the JJ E34Ls are the way to go (they are better at handling high voltages than the EL34s). They cost half what the KT88s do too...
I'm ordering everything right now...
I went finally with the GXSE's.
I'm thinking on ordering JJ EL34L's, JJ ECC81's, Sino or Sovtek's 5AR4 and one set of EH KT88.
I wonder, will the Genalex Gold Lion reissue make a difference from the EH's with the GSXE's? will they be worth? In such case, what's a good, not too conservative bias point for them? I was going to run the EH's KT88 at B+ 450V, 5K OPT and 430 Rk, that's about 36Watts power disipation. Do the Genalex take it w/o issues?
What would be a sweet spot for the Genalex/GSXEs taking into account the Edcor OPT's seem to "sing" better at high currents?
About to send the Digikey's order, apart from inrush limiters like CL-90 to save on wimpy current production 5AR4's, are there any other recommended components not mentioned in tubelab.com? I won't use standby switch nor SS diodes.
I went finally with the GXSE's.
I'm thinking on ordering JJ EL34L's, JJ ECC81's, Sino or Sovtek's 5AR4 and one set of EH KT88.
I wonder, will the Genalex Gold Lion reissue make a difference from the EH's with the GSXE's? will they be worth? In such case, what's a good, not too conservative bias point for them? I was going to run the EH's KT88 at B+ 450V, 5K OPT and 430 Rk, that's about 36Watts power disipation. Do the Genalex take it w/o issues?
What would be a sweet spot for the Genalex/GSXEs taking into account the Edcor OPT's seem to "sing" better at high currents?
About to send the Digikey's order, apart from inrush limiters like CL-90 to save on wimpy current production 5AR4's, are there any other recommended components not mentioned in tubelab.com? I won't use standby switch nor SS diodes.
Boris_The_Blade said:
Yep, more expensive than mouser, but better for hard to find parts. Thanks for the tip
chrish said:
I know, I looked for info on these in the forum, and yours an other (seems a general consensus) opinions was what made me choose them. Thanks!
Anyone on the Genalex/Edcor GXSE-XSE?
At the time that I compiled the parts list I tested a big bunch of capacitors on a HP component analyzer. The Panasonic capacitor specified was chosen because it had the lowest ESR of the 15 or so capacitors that I had available to test. I doubt that it really makes much difference, but the engineer in me tends to choose the best available component for the job, especially when the cost differences are small. I did the same with the output tube capacitor. I no longer have access to that analyzer.
You could probably substitute any similar sized parts within reason. I would use at least 270 uF in the driver circuit (20 ohms reactance at 30 Hz). A 6.3 volt rating is adequate.
Use at least 680 uF in the output circuit (8 ohms reactance at 30Hz) especially if CFB is used. The output stage capacitor should be rated for operation at 105 degrees C simce it will absorb some heat from nearby tubes. A 50 volt or 63 volt rated capacitor is required.
The boards were shipped Saturday.
Tubes are here, we finally got Gold Lion's.
PCBs are here also!
I'm afraid the latest items will be the transformers.
A question, I see the OIL motor run capacitor goes after the choke or first cap.
What's the improvement? I can see it if all were motor run oil caps, or at least the first (though 80uF will be too much for the 5AR4?) as it will take the harder job after the rectifier.
Will it take out stress from the rest of caps? wouldn't a bigger electrolitic cap provide more improvement?
PCBs are here also!
I'm afraid the latest items will be the transformers.
A question, I see the OIL motor run capacitor goes after the choke or first cap.
What's the improvement? I can see it if all were motor run oil caps, or at least the first (though 80uF will be too much for the 5AR4?) as it will take the harder job after the rectifier.
Will it take out stress from the rest of caps? wouldn't a bigger electrolitic cap provide more improvement?
The idea is to provide a low impedance output from the power supply to feed the amplifier. Therefore you want the best capacitor electrically closest to the output transformers. This means the second capacitor. An oil filled, or a polypropelyne motor run (not start) capacitor has the lowest ESR (effective series resistance) over the widest frequency range of any low cost capacitors. Using a better quality electrolytic is good, but most electrolytics start to behave like inductors at the highest audio frequencies. Upgrading the first capacitor offers little benefit and increasing the value makes life tough on the rectifier tube.
At least one builder used motor run capacitors for both capacitors and left the electrolytics off of the board. He reported excellent results, but the firsr cap should still be 50 uF or less.
At least one builder used motor run capacitors for both capacitors and left the electrolytics off of the board. He reported excellent results, but the firsr cap should still be 50 uF or less.
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