The "$250" Amp? - 6LU8 Compactron SE, UL
- Thread starter Wigwam Jones
- Start date
mashaffer
Super Member
Well I just got my much anticipated heavy but small box from Radio Daze with the bulk of the parts for my project. I got lots of caps and resistors along with two 4 henry PS chokes. Now I have to work on figuring out the right layout. 
I will be very busy for a few days as I have to be up a 3AM on Wednesday to get my wife to out patient foot surgery and then off to rehab. I will try to get a pic of the organ chassis that I plan to use posted before the weekend so that I can solicit ideas.
mike
I will be very busy for a few days as I have to be up a 3AM on Wednesday to get my wife to out patient foot surgery and then off to rehab. I will try to get a pic of the organ chassis that I plan to use posted before the weekend so that I can solicit ideas.
mike
vinylkid58
Super Member
Mike,
Great to hear your project is moving along. I'm interested to see how your amp turns out.
I've been sidetracked by my big amps conversion from EL34's to 6BG6GA's. I was running them too hard and lost one tube and a resistor.:sigh: I guess it could have been worse.
Jeff
Great to hear your project is moving along. I'm interested to see how your amp turns out.
I've been sidetracked by my big amps conversion from EL34's to 6BG6GA's. I was running them too hard and lost one tube and a resistor.:sigh: I guess it could have been worse.
Jeff
mashaffer
Super Member
Here is the chassis
Well here is the chassis. I plan to mount it on a skirt made from 1x6 pine.
The PT location is obvious. The can caps are going to be removed and I plan to put the two 4H PS chokes in that area. I could put the rectifier in one of the resulting holes I suppose but the original had it to the right of the PT.
The 6L6 power tubes in the original amp were in the two sockets further to the right (the one with the 9pin mini in between them) and I thought to put the 6LR8 sockets there and the OPTs under the chassis between the sockets and the rear of the chassis.
Now here is the trick. I need 8 9pin mini sockets for the rest of the circuitry. The phono preamp has 1 12AY7, 1 12AX7, and 2 12AU7 while the crossover will have 4 12AU7 including the CF buffer at the input to the crossover section.
My thought was to put the phono section toward the upper right hand corner to keep it away from the PS section and as far away from the power tubes as possible. There are four mini sockets in that area with two octal size connectors to the right. I could use the four existing sockets but if I made some kind of reducer and removed those connectors replacing with mini sockets on the reducer I could get the phono section farther away from PS that way.
I figure that the crossover buffer tube could go between the 6LR8s without causing any problem. In any case I will have to had some mini sockets somehow in the holes from larger sockets removed.
There are a couple other octal size connectors one of which (probably the one between the output tubes and original rectifier socket) I would like to reserve for future use for a wired remote.
I would appreciate any suggestions. Also should I open a new thread for discussing this amp since it is a little bit more complex than the $150 amp?
mike
Well here is the chassis. I plan to mount it on a skirt made from 1x6 pine.
The PT location is obvious. The can caps are going to be removed and I plan to put the two 4H PS chokes in that area. I could put the rectifier in one of the resulting holes I suppose but the original had it to the right of the PT.
The 6L6 power tubes in the original amp were in the two sockets further to the right (the one with the 9pin mini in between them) and I thought to put the 6LR8 sockets there and the OPTs under the chassis between the sockets and the rear of the chassis.
Now here is the trick. I need 8 9pin mini sockets for the rest of the circuitry. The phono preamp has 1 12AY7, 1 12AX7, and 2 12AU7 while the crossover will have 4 12AU7 including the CF buffer at the input to the crossover section.
My thought was to put the phono section toward the upper right hand corner to keep it away from the PS section and as far away from the power tubes as possible. There are four mini sockets in that area with two octal size connectors to the right. I could use the four existing sockets but if I made some kind of reducer and removed those connectors replacing with mini sockets on the reducer I could get the phono section farther away from PS that way.
I figure that the crossover buffer tube could go between the 6LR8s without causing any problem. In any case I will have to had some mini sockets somehow in the holes from larger sockets removed.
There are a couple other octal size connectors one of which (probably the one between the output tubes and original rectifier socket) I would like to reserve for future use for a wired remote.
I would appreciate any suggestions. Also should I open a new thread for discussing this amp since it is a little bit more complex than the $150 amp?
mike
Attachments
mjennens
Old Guys Rule!!!
I came upon this thread a little late. Anyway, I found the schematic for the amp, but is there a BOM that I might have missed?
If I decide to do this, it will be my first tube amp build. Most of the components look pretty straight forward to source; PE has most of them.
Oops, just saw that the BOM will be out after the AK Fest. I'll keep an eye out for it.
I'm not sure about the transformers though. Are there particular ones, maybe by manufacturer and part number, that someone could recommend. I looked at the Hammonds on the PE site and either the 272BX or 272JX seem like the correct one. And the Hammond 1609 looks like the correct OT. Yes, no?
Any suggestions on caps? PE has them all, but are they decent quality?
Finally, other than where it states 5 watt resistors, are 1 watt flame proof OK?
Sorry if this has all been stated earlier.
Thanks for any help/direction/advice.
Mike
If I decide to do this, it will be my first tube amp build. Most of the components look pretty straight forward to source; PE has most of them.
Oops, just saw that the BOM will be out after the AK Fest. I'll keep an eye out for it.
I'm not sure about the transformers though. Are there particular ones, maybe by manufacturer and part number, that someone could recommend. I looked at the Hammonds on the PE site and either the 272BX or 272JX seem like the correct one. And the Hammond 1609 looks like the correct OT. Yes, no?
Any suggestions on caps? PE has them all, but are they decent quality?
Finally, other than where it states 5 watt resistors, are 1 watt flame proof OK?
Sorry if this has all been stated earlier.
Thanks for any help/direction/advice.
Mike
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GOYA
Super Member
I just want to be sure:
Is this an UL OPT? The screen tap is 40%
http://www.edcorusa.com/Products/ShowProduct.aspx?ID=427
Is this an UL OPT? The screen tap is 40%
http://www.edcorusa.com/Products/ShowProduct.aspx?ID=427
GOYA
Super Member
You see, this is an Antec 3T275. Here's a link to the specs:
http://www.antekinc.com/trans.html
http://www.antekinc.com/AN-3T275.pdf
Now, in the pdf file you see above, it gives this rating:
I/P 115 V
I/P 115 V
O/P 275 V
O/P 275 V
O/P 6.3V 4 Amp
O/P 12.6 V 3 Amp
But that's not what it is.
It is this:
Notice - no 12.6 V O/P. So Squidward called them up and it turns out that the real specs for this transformer are 6.3 V @ 5 amps and 6.3 V @ 5 amps.
At least, that's what we think at the moment.
An update on this transformer. I ordered one from John at Antek and he told me that it changed again. It now has a 12.6v secondary again. But John said he could give me a center tap on the 12.6v winding. So it should still work for this amp project. I've forgotten exactly how many amps are on the 12.6v but there are 4 amps available on the 6.3v winding. If I use half of the 12.6v for the rectifier heater, do I need to do anything with the other half? Would it make more sense to use the two halves of the 12.6v winding to heat the 6LU8s?
Also, it's not on the schematic, what size fuse should be used?
Any progress on the project?
Kegger
R.I.P. 1/12/1966 - 6/1/2017
Here's info from an earlier answered post
"
Quote:
Originally Posted by lloydrmc View Post
Speaking of buying parts, there was some talk of buying the 5K16 Edcor so it
would give you a 2.5K primary with 8 an ohm speaker. Am I correct in assuming
that 5K turned out to be the number after all?
On the schematic:
What is voltage rating on caps?
What does "Pol" mean? No luck so far finding anything "poly..."
with 220uF capacity in Mouser catalog.
Power resistor is no problem, and even not that expensive:
http://www.mouser.com/Search/Product...MtnSCr3Q== t
hough I'm sorely tempted to get the cool-looking aluminum heatsinked ones
(http://www.arcol.co.uk/uploads/products/hsseries-10.pdf) -
they're still not that spendy, and they are 1% after all.
What wattage, composition, tolerance on resistors with no wattage rating on the schematic?
Thanks again. END.. Quote
-----------------------------------
Yes the 5K 8ohm tranny is the one to use if your primarily running the amp on 8ohm speakers.
(4ohm version on 4ohm speakers and 16ohm version on 16ohm speakers, all the 5K variants)
The amp responds well using 4,8,16ohm speakers with the 8ohm tranny, so it is flexible though.
On the schematic “POL” stands for polarized, electrolytic and showing the polarity if one is used.
A poly or oil cap is just fine as well an may even be an upgrade, so yes try them if you have them.
Voltages are on the schematic, so cap voltages should follow with say a 50% increase or more of
voltage rating on the cap in that position, so if you have 300v then a 450v is more then adequate,
150v at the coupling area would mean say a 225v rating or higher cap, at the output cathode 37v
then a 50v cap would work but I’d probably go at least 75v there, again any kind of cap you want
to use will work, except the coupling cap C1 needs to be a non polarized better quality cap of say
at least a poly, a nice Russian oil cap would serve very well here, same as C5 and C4 if used to.
Resistors are all 1/2watt except were specified, again any kind will work, but I’d use primarily the
carbon film type, maybe carbon comp for the 100k plate load resistors, metal film for the 2.7k RC
filter and wire wound for the output cathode resistors. Tolerance is not critical either, just so they
are fairly equal between both channels should be just fine."
-------------
And by the way I am still hoping Squid will be posting here with the BOM SHORTLY!!
"
Quote:
Originally Posted by lloydrmc View Post
Speaking of buying parts, there was some talk of buying the 5K16 Edcor so it
would give you a 2.5K primary with 8 an ohm speaker. Am I correct in assuming
that 5K turned out to be the number after all?
On the schematic:
What is voltage rating on caps?
What does "Pol" mean? No luck so far finding anything "poly..."
with 220uF capacity in Mouser catalog.
Power resistor is no problem, and even not that expensive:
http://www.mouser.com/Search/Product...MtnSCr3Q== t
hough I'm sorely tempted to get the cool-looking aluminum heatsinked ones
(http://www.arcol.co.uk/uploads/products/hsseries-10.pdf) -
they're still not that spendy, and they are 1% after all.
What wattage, composition, tolerance on resistors with no wattage rating on the schematic?
Thanks again. END.. Quote
-----------------------------------
Yes the 5K 8ohm tranny is the one to use if your primarily running the amp on 8ohm speakers.
(4ohm version on 4ohm speakers and 16ohm version on 16ohm speakers, all the 5K variants)
The amp responds well using 4,8,16ohm speakers with the 8ohm tranny, so it is flexible though.
On the schematic “POL” stands for polarized, electrolytic and showing the polarity if one is used.
A poly or oil cap is just fine as well an may even be an upgrade, so yes try them if you have them.
Voltages are on the schematic, so cap voltages should follow with say a 50% increase or more of
voltage rating on the cap in that position, so if you have 300v then a 450v is more then adequate,
150v at the coupling area would mean say a 225v rating or higher cap, at the output cathode 37v
then a 50v cap would work but I’d probably go at least 75v there, again any kind of cap you want
to use will work, except the coupling cap C1 needs to be a non polarized better quality cap of say
at least a poly, a nice Russian oil cap would serve very well here, same as C5 and C4 if used to.
Resistors are all 1/2watt except were specified, again any kind will work, but I’d use primarily the
carbon film type, maybe carbon comp for the 100k plate load resistors, metal film for the 2.7k RC
filter and wire wound for the output cathode resistors. Tolerance is not critical either, just so they
are fairly equal between both channels should be just fine."
-------------
And by the way I am still hoping Squid will be posting here with the BOM SHORTLY!!
GOYA
Super Member
That would be great.
Thanks Kegger. I looked at that post earlier for resistor type but the cap voltages escaped me. It looks like I've got everything I need except for the iron. That shouldn't be too much longer.
(I'm still not sure of the fuse size but that can wait.)
Slightly off topic, but...
That chassis is from a Baldwin Orgasonic, model 51P I believe. I've got one just like it out in the garage right now. Mike probably already knows this. Here's another photo showing most of the organ's chassis (not my photo, but it gives you an idea). The amp chassis is as the far right end.
On with the 6LU8. I'm kinda interested in this project myself...
sled108
Super Member
A 10" X 2" Round Cake Pan works Sweetly....
Check it out....
http://www.youtube.com/watch?v=GkdiesXD4gc
Check it out....
http://www.youtube.com/watch?v=GkdiesXD4gc
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