The "$250" Amp? - 6LU8 Compactron SE, UL
- Thread starter Wigwam Jones
- Start date
Mike Stehr
Poverty Audio
So if a 6LU8 is more or less half a 12AT7 and a EL-34 in one bottle, couldn't one lash up this circuit using a actual 12AT7 and EL-34, and kind of come up with the same sonic characteristic of the 6LU8?
I have 12AT7 and EL-34....I don't have any 6LU8's, just some weird shit like 6Y7A and HK7. I think HK7 is half diode half pentode if I recall.
I have 12AT7 and EL-34....I don't have any 6LU8's, just some weird shit like 6Y7A and HK7. I think HK7 is half diode half pentode if I recall.
Wigwam Jones
Caesar non supra grammati
I don't know, but if it is, you're more than welcome to do things your way as we do our build. But we're going to do the 6LU8. This is for the newbies who have no tubes at all, so buying a pair of 6LU8 won't be an issue. We're not going to let this project get off track by contaminating the build with alternative methods, circuits, and tubes. If you know enough to do the substitution yourself, then by all means. But we are going to stick with one methodology.
Wigwam Jones
Caesar non supra grammati
Yeah, but it exploded in a good way, don't you think?
Wigwam Jones
Caesar non supra grammati
I just want to be there to take notes and photos so that I know what is important when we do the 'real' build.
Not for display, for me to absorb. If it's ok with you guys.
I have taken the time to follow along from he begining of this idea and like -sug-from Kegger-Squidward-Pacprotecter-one ? have you concidered the 5V4G rectifier tube due to its cathode-rather than filament type emmitter-it would serve not only as an efficient rectifier,but also as a delay circuit letting ther tubes warm up before high voltage is applied. It is more robust than the ez81 with arround 22 volts/plate drop-but would also lessen heat builup on power tranny.
Kegger
R.I.P. 1/12/1966 - 6/1/2017
The 5V4G is a fine rectifier, I use them a lot. But the EZ81 is also a slow warmup
type rectifier as well so if it's used the high voltage delay is well utilized here.
(6BY5 is basically a 6.3v version of the 5V4G rectifier and could be used)
Were also not worried about how robust the rectifier is as the EZ81 is plenty beefy
for this project with room to spare. Also the power transformer being considered on
this project does not have a 5 volt winding, also the EZ81 does not need its own 6v
winding as it's cathode wiring is not attached to the heater wiring.
type rectifier as well so if it's used the high voltage delay is well utilized here.
(6BY5 is basically a 6.3v version of the 5V4G rectifier and could be used)
Were also not worried about how robust the rectifier is as the EZ81 is plenty beefy
for this project with room to spare. Also the power transformer being considered on
this project does not have a 5 volt winding, also the EZ81 does not need its own 6v
winding as it's cathode wiring is not attached to the heater wiring.
Kegger
R.I.P. 1/12/1966 - 6/1/2017
To a degree yes, and that's what I'm using in spice simulation to fine tune this
circuit, once were done one could more then likely build this with a single 12AT7
and a pair of EL34's on there own build. (I would up the power supply voltage)
keep in mind these tubes are not identical so some tweaking may need to be done.
Also the EL34 is a much beefier tube so voltages/power dissipation can be increased.
dnewma04
The Healer
I can get the sockets needed for the 6LU8 for 3.50 each if I can get an order of 20 or more together. Not sure if it would be worthwhile to have me get them and distribute rather than just ordering on your own. I suppose if I was conned into doing some chassis work, I could mount them before shipping, but that would take away some of the DIY fun.
And at this point, i'm not sure I can be conned into the chassis work.
And at this point, i'm not sure I can be conned into the chassis work.
similost
Rockin and Rollin....
SOoooo... when I start building mine, and since you're not posting the pictures, does that mean I go after the forum, the designers, or you when I solder a cap in backwards and get shrapnel all in my face?
Wigwam Jones
Caesar non supra grammati
SOoooo... when I start building mine, and since you're not posting the pictures, does that mean I go after the forum, the designers, or you when I solder a cap in backwards and get shrapnel all in my face?
Before we begin the group build, there will be photos posted for every step, along with textual instructions, definitions (glossary and FAQ) and theory of operation. I don't want anyone to be having to solder part a to wire b without having a good understanding of what they're doing, why, and with a very clear photo of before, during, and after. If anything, this will be so overdocumented that more experienced people will get bored.
Wigwam Jones
Caesar non supra grammati
Either the bull by the horns or the tiger by the tail, eh? I just want this to go well for all the n00bs like myself.
Mike Stehr
Poverty Audio
I was just asking Kegger a question, I never planned to contaminate anything........
Since there is some similiar aspects between the 6LU8 and 12AT7 and EL-34, I didn't think the question was too much off-topic.
I was thinking of maybe breadboarding up that circuit that Kegger posted using EL-34 and 12AT7, that's why I asked.
Kegger answered my question, and I appreciate it very much.
He also mentioned EL-34 can be ran at a higher operating point, like I thought.
I even think he mentioned the simulations he is running are based on 12AT7 and EL-34 parameters.
Plus that schematic is using plate to plate, or plate to grid feeedback, which I have some interest in.
My apologies......I'll avoid the thread from now on.....
Mike
Wigwam Jones
Caesar non supra grammati
No harm, no foul, Mike. I thought you were suggesting a mod for the project. I will try to parse a bit more carefully in the future - my apologies too.
OK, and Antek has been ordered. I think I can scare up most of the rest of the parts from my junkbox. We should have a prototype amp in a week, or so. If you want to be around while I build it, Wiggy, that would not be a problem at all! I'd love the company! I admit that I'm not much of a conversationalist while I'm building something, but if you don't mind I don't either!
Chassis options are still up in the air. I don't know what I'll build the prototype on, and I have no idea if it will be the same as the finished project or not. I was looking at cheap chassis options, to help keep costs down. One choice is to use a heavy duty industrial aluminum cake pan. Another option is the standard Hammond box, with the option of having a cage easily mounted later. The final option would be a flat aluminum plate with a wooden box base. How important is the cage option? If it's pretty important, I'll focus on Hammond chassis for the final build.
Chassis options are still up in the air. I don't know what I'll build the prototype on, and I have no idea if it will be the same as the finished project or not. I was looking at cheap chassis options, to help keep costs down. One choice is to use a heavy duty industrial aluminum cake pan. Another option is the standard Hammond box, with the option of having a cage easily mounted later. The final option would be a flat aluminum plate with a wooden box base. How important is the cage option? If it's pretty important, I'll focus on Hammond chassis for the final build.
Wigwam Jones
Caesar non supra grammati
I would say a cage is not an important option. I may want one myself, but most people don't use 'em, they raise the price, and we want to stick with cheap whenever possible.
Mike:
A lot of these projects suffer a death of a thousand modifications, as others have pointed out. I am sure that Wiggy is simply trying to keep the train on the tracks. Please don't go over a misunderstanding.
I like your idea of implementing this with an EL34 and 12AT7, especially if you happen to have these on hand. I built a RH84, and rather than use the 12AT7, I opted to use two 7 pin replacements, the 6ab4. It worked great. I bet you will have similar success with your amplifier. Keep us posted on the progress!
A lot of these projects suffer a death of a thousand modifications, as others have pointed out. I am sure that Wiggy is simply trying to keep the train on the tracks. Please don't go over a misunderstanding.
I like your idea of implementing this with an EL34 and 12AT7, especially if you happen to have these on hand. I built a RH84, and rather than use the 12AT7, I opted to use two 7 pin replacements, the 6ab4. It worked great. I bet you will have similar success with your amplifier. Keep us posted on the progress!
wank
Moks by popular demand
I'm loving this thread. My only regret is that it didn't end up with sexier looking tubes - some of those tubes like Kegger uses with the cap terminal thingy on top and say a 5y3 rectifier (I have one with the big bottle shape).
Is there a source for all of these 6LU8s?
(Oh yeah - thanks for the Pak-to-English translations Squidward.)
Is there a source for all of these 6LU8s?
(Oh yeah - thanks for the Pak-to-English translations Squidward.)
