PakProtector
AK member
hey-Hey!!!,
So what was the cause of the overheated resistor?
cheers,
Douglas
So what was the cause of the overheated resistor?
cheers,
Douglas
The "$250" Amp? - 6LU8 Compactron SE, UL
- Thread starter Wigwam Jones
- Start date
Kegger
R.I.P. 1/12/1966 - 6/1/2017
A minor wiring issue. 
The wiring that was suppose to go to the plate of the triode was
swapped with the wiring that was suppose to go to the plate of the
pentode, man did it finally make sense when I put that scene in the
sim, the screen was drawing 24ma!
Yah that'll eat up the screen resistors allright, well after rewiring the
amp the voltages were where they should be.
I made some cathode resistor adjustments and power supply tweaking,
the amp is working well, I'll post some pic's and update the schem later.
------------
At the moment I'm killing my back hauling heavy speakers in the basemeant.
The wiring that was suppose to go to the plate of the triode was
swapped with the wiring that was suppose to go to the plate of the
pentode, man did it finally make sense when I put that scene in the
sim, the screen was drawing 24ma!
Yah that'll eat up the screen resistors allright, well after rewiring the
amp the voltages were where they should be.
I made some cathode resistor adjustments and power supply tweaking,
the amp is working well, I'll post some pic's and update the schem later.
------------
At the moment I'm killing my back hauling heavy speakers in the basemeant.
bricktop
Couch woofer
hey Douglas!
Hey Kegger, I got the transformers and tubes I need, i'll experiment tonite :thmbsp:
Kegger
R.I.P. 1/12/1966 - 6/1/2017
Cool Brick I think your going to like it.
A hint to cathode resistors, 820ohm on the pentode and 620ohm
on the driver is where I am, the "pentode" draws quite a bit like a
KT88 or 6550 would in this setup. (should be good starter values)
(50ma output, 3.6ma driver with those resistors) "adjusted below"
(Triode/UL mode and I'm running a 295v supply)
-----
EDIT: I Paralelled a 5K resistor to the 820 pentode cathode resistor
so when using 6MF8 you get decent current without changing a bit.
Just making it a little more tube rollin friendly, gotta be roll friendly!
A hint to cathode resistors, 820ohm on the pentode and 620ohm
on the driver is where I am, the "pentode" draws quite a bit like a
KT88 or 6550 would in this setup. (should be good starter values)
(50ma output, 3.6ma driver with those resistors) "adjusted below"
(Triode/UL mode and I'm running a 295v supply)
-----
EDIT: I Paralelled a 5K resistor to the 820 pentode cathode resistor
so when using 6MF8 you get decent current without changing a bit.
Just making it a little more tube rollin friendly, gotta be roll friendly!
This is a great effort and all construction of any amp may have minnor problems and are expected-mine has ben built on an old scott tunner metal housing -the metal work has ben drilled-trannys mounted-tube sockets-front and back pannel boards and im using apiece of plywood for the bottom-must be inventive out in the deep woods of N.H.
dnewma04
The Healer
Yes, i'm sure once all the toob noobs complete their first beginner amp, they will step right into building their own execution device.
Maybe, a seperate thread for this idea might be more appropriate?:scratch2:
shelly_d
Not An Audiophool
Building this and testing it would make one a candidate for the Darwin Awards - my $.02 worth.:stupid:
Kegger
R.I.P. 1/12/1966 - 6/1/2017
Hey Hey!
Couple O glory shots!
One of the amp it'self and of the setup it's currently in.
-----------------
So far so good, been in 3 systems with 3 sets of speakers, some tweaking has
been done, it's got a couple set of speakes left to go, but even the demanding
speaker loads have come through with flying colors.
Were inching O so close!
The schem on the front page has been updated to this build.
Couple O glory shots!
One of the amp it'self and of the setup it's currently in.
-----------------
So far so good, been in 3 systems with 3 sets of speakers, some tweaking has
been done, it's got a couple set of speakes left to go, but even the demanding
speaker loads have come through with flying colors.
Were inching O so close!
The schem on the front page has been updated to this build.
Attachments
PakProtector
AK member
hey-Hey!!!,
On the 'Big One' build, we should put it in another thread.
There are a few things we've learned with this 6LU8 build. The more important one IMO is the 'build it simplest' first. There were some issues discovered from building it a bit more experimenter-friendly that have been worked out. Once the amp is working it is lots easier to make single mods to its circuit to test the effects, rather than trying to troubleshoot the 'all-in-one' construction methods.
I believe that is why the usual path the builders have started on is to get an existing amp and playing with that until the learning curve flattens out a bit( I know I did it this way, and I've heard others describe similar work ). Without some good supprot, the 'first build' can be a daunting task, yes?
cheers,
Douglas
On the 'Big One' build, we should put it in another thread.
There are a few things we've learned with this 6LU8 build. The more important one IMO is the 'build it simplest' first. There were some issues discovered from building it a bit more experimenter-friendly that have been worked out. Once the amp is working it is lots easier to make single mods to its circuit to test the effects, rather than trying to troubleshoot the 'all-in-one' construction methods.
I believe that is why the usual path the builders have started on is to get an existing amp and playing with that until the learning curve flattens out a bit( I know I did it this way, and I've heard others describe similar work ). Without some good supprot, the 'first build' can be a daunting task, yes?
cheers,
Douglas
Eh, the amp didn't work right the first time because I had a pair of wires going to the wrong place on each SP. Swap the wires, and it worked. I finished it literally the morning before the SMAC meet, and didn't have much time to debug it. This is a prototype, anyway. I believe Kegger is pretty happy with the end result. I also believe that most of the circuit changes that he's made are due to his modeling software not having the exact tube that we are using, and he's finding that real-world operation to be slightly different than the computer model he used. The prototype has been adequate for his R&D purposes.
As for the final build, I agree, it should be as simple as possible. We will support a set of upgrades after the amp is built. We will have a build that centers around a readily available piece of hardware, too, like a Hammond chassis (I already have my eye on a particular one).
As for the final build, I agree, it should be as simple as possible. We will support a set of upgrades after the amp is built. We will have a build that centers around a readily available piece of hardware, too, like a Hammond chassis (I already have my eye on a particular one).
VinylRob
Vinylphile
><((((º>`·.¸¸.·´¯`·.¸.·´¯`·...¸><((((º>`·.¸¸.·´¯ `· .¸.·´¯`·...¸><((((º>
Just trying to swim with the big fish here.
Hewwww! Just made it through the whole thread and I think I need a beer. You guys have a great little project, based around a most interesting little bottle. In the SMAC group we DO have Wizards and Sorcerers and are a power to be reckoned with! Nice job, can't wait to hear one or three of them.
Let me know, I'll bring a big bag of fresh vinyls and a couple of cold ones.
Cheers!
Happy (6LU8) Listening!
Just trying to swim with the big fish here.
Hewwww! Just made it through the whole thread and I think I need a beer. You guys have a great little project, based around a most interesting little bottle. In the SMAC group we DO have Wizards and Sorcerers and are a power to be reckoned with! Nice job, can't wait to hear one or three of them.
Let me know, I'll bring a big bag of fresh vinyls and a couple of cold ones.
Cheers!
Happy (6LU8) Listening!
Belive me I know how it feels to build something and the oh no -----comes out instead of music--testing and trial and error-intuitve reasoning-and time to relax and look at the problems after a few days off always helps -I have lost sleep over tube stuff believe mee, with bugged out eyes.Then like a light comes on thats it factor hitsand a big smile too.
Kegger
R.I.P. 1/12/1966 - 6/1/2017
I hear yu Bruce!
Well the amp sounds great, works great and I believe I'm done tweaking the circuit.
(Schematic on page one has been updated)
All areas of the amp sound really really nice from top to bottom, but I don't think I have had
an amp in my system that has sounded near as good on the top end, chrystal clear, detailed
and smooth, cymbols an guitar sound extraordinary and there's plenty of air.
No there's not "pounding deep" bass from this amp but it has good well defined bass, actually
the whole amp is well defined and clear sounding, plus a nice large clean image for sure.
So far my favorite tubes are GE Grey Plate Side Getters!:yes:
Well the amp sounds great, works great and I believe I'm done tweaking the circuit.
(Schematic on page one has been updated)
All areas of the amp sound really really nice from top to bottom, but I don't think I have had
an amp in my system that has sounded near as good on the top end, chrystal clear, detailed
and smooth, cymbols an guitar sound extraordinary and there's plenty of air.
No there's not "pounding deep" bass from this amp but it has good well defined bass, actually
the whole amp is well defined and clear sounding, plus a nice large clean image for sure.
So far my favorite tubes are GE Grey Plate Side Getters!:yes: