Ok, Im not a complete n00b, but new to many things. I have built a plentiful amount of headphone amplifiers, a submini tube 1w guitar amp, a gain clone, and random other things over the last few years. I am 25, so fairly new to all this (3-4 years?). I have recently built some open baffle speakers based on this driver. Now I want to build a simple SET to drive it. I have never used Octal tubes so this is one of the requirements. I don't need MUCH power because I live in a small apartment all by myself.
This is was I want
1.5-3w power
octal tubes
simple
~$200 usb not including case.
This is what I've found:
This 6EM7 amp
with these output transformers
Now the power supply is the part I really need help with. with the power transformer and 2 chokes I get a over what I feel reasonable to spend on iron. I know it is VERY important but I want to start lowish and hearthe differences as I build other things throughout the years. Also, the Edcor output transformers "look" decent to me. I like the blue and the label, ha!
heres the schematic for easy viewing.
This is was I want
1.5-3w power
octal tubes
simple
~$200 usb not including case.
This is what I've found:
This 6EM7 amp
with these output transformers
Now the power supply is the part I really need help with. with the power transformer and 2 chokes I get a over what I feel reasonable to spend on iron. I know it is VERY important but I want to start lowish and hearthe differences as I build other things throughout the years. Also, the Edcor output transformers "look" decent to me. I like the blue and the label, ha!
heres the schematic for easy viewing.
An externally hosted image should be here but it was not working when we last tested it.
Last edited:
What is your budget? What power transformer are you planning on using? Hammond 158Q ($22) or 159P ($28), around $50 a pair for a choke input supply. If you are just playing around you could always do an RC smoothed supply and save the choke costs. Remember those resistors sitting under the power triode are at least 10W units which adds a bit of cost. You might as well knock out a bill of materials to see what you are looking at money wise.
Matt
Matt
Once again, the Greinacher (full wave) voltage doubler "rides to the rescue". 
I know of no better way to build a highly competent PSU, while spending comparatively little money. You can use the B+ supply from "El Cheapo" (schematic) attached, with little change.
Buy the B+ power "iron" from Allied Electronics. Stock # 967-2343 is the Triad N-77U isolation trafo. Stock # 967-1004 is a highly suitable Triad C-24X filter choke.
As shown, you will not get to 325 VDC, but you will come close. If you are determined to have 325 V., we will discuss boosting techniques.
I know of no better way to build a highly competent PSU, while spending comparatively little money. You can use the B+ supply from "El Cheapo" (schematic) attached, with little change.Buy the B+ power "iron" from Allied Electronics. Stock # 967-2343 is the Triad N-77U isolation trafo. Stock # 967-1004 is a highly suitable Triad C-24X filter choke.
As shown, you will not get to 325 VDC, but you will come close. If you are determined to have 325 V., we will discuss boosting techniques.
Attachments
Well It doesn't have to be THAT cheap, and it would be interesting to use a tube rectifier (I haven't tried that either yet). I used a step-up transformer on my guitar amp which worked but it was tricky with wiring and hum.
I was thinking something like this from Edcor again for power, and that already puts me just over 100$ for transformers. another 50 for chokes and I only have 50 left for everything else! Max MAX budget would be $300, but that's really pushing it.
Eli, that is interesting for sure, but as I understand it, I need at least the 325v to get enough "clean" watts on my output.
I was thinking something like this from Edcor again for power, and that already puts me just over 100$ for transformers. another 50 for chokes and I only have 50 left for everything else! Max MAX budget would be $300, but that's really pushing it.
Eli, that is interesting for sure, but as I understand it, I need at least the 325v to get enough "clean" watts on my output.
An externally hosted image should be here but it was not working when we last tested it.
Last edited:
If you are looking to save cost, the tube rectifier can be replaced by solid state.
Have you considered the Tubelab Simple SE? It can be made cheaply, adding options later to improve the power supply. It is a great amp with plenty of support. My first tube amp. Simple SE schematic
These power tubes are cheap and work very well RARE !!! 5881 = 6L6GC = 6P3S-E tubes. Lot of 2 NOS - eBay (item 190513706521 end time Apr-17-11 11:45:03 PDT)
Have you considered the Tubelab Simple SE? It can be made cheaply, adding options later to improve the power supply. It is a great amp with plenty of support. My first tube amp. Simple SE schematic
These power tubes are cheap and work very well RARE !!! 5881 = 6L6GC = 6P3S-E tubes. Lot of 2 NOS - eBay (item 190513706521 end time Apr-17-11 11:45:03 PDT)
I have looked at the Simple SE, Im sure it a great amp but it just doesn't quite "grab" me. I'm picky the way I pick my projects I guess. I think I am pretty stuck on this design, its just the power supply is really adding up quickly.
Do I really need one choke per channel? is there a better rectifier to use? or what about a solid state rectifier, what would I gain/lose by going that route and how would it play in my "cost".
Do I really need one choke per channel? is there a better rectifier to use? or what about a solid state rectifier, what would I gain/lose by going that route and how would it play in my "cost".
OK, boosting technique time it is. Add Allied stock # 967-8020 to the mix. That trafo has 2X 3.3 A./"12" V. secondaries. You will use 1 of the secondaries to power the 6EM7 heaters. Wire the heaters in series, for "12" V. operation. The junction of the heaters will be the point to which bias off B+ will be applied. You have to phase up the remaining "12" V. secondary and the secondary of the N-77U. The windings are wired in series. One arrangement will yield approx. 133 VAC, while the 2nd yields approx. 107 VAC. You will Greinacher double the larger voltage. That gets you past the "magic" 325 VDC.
Gary Kaufman set things up as pseudo dual mono, for improved channel separation. The "El Cheapo" PSU is pseudo dual mono, only for small signal. So, things get tweaked a bit. The 820 μF. doubler stack caps. and single filter choke stay as is. Follow the filter choke with a 47 μF. 'lytic. The UF4007s at split point are fine, as they can tolerate up 1 A. of forward current. You will have to experiment with the value of the following resistors to bring the B+ rail voltage in where desired. The final reservoir caps. are as Gary showed.
Last edited:
If you've decided on the 6EM7 tube, take a look at Pete Millett's "Jonokuchi" amplifier for inspiration. His amp uses the 13EM7, which is the same tube but with a different heater voltage. Edcor sells a transformer kit for his amp. It is available at a small discount. (EDCOR Electronics Corporation. PM-101)
You can build the Jonokuchi point to point, and skip the cost of the circuit board. You might even take his power supply design and build the Kaufman amp around it. Pete's power supply should make about 340 volts.
You can get a lot of Henries for your dollar if you buy the Triad filter chokes. The C-14X is popular. At the low currents you will draw, the C-7X should work fine too. Otherwise, just use a lot of capacitance. If you've got 400uF~800uF, you could probably skip the filter choke entirely and still not be bothered by excessive hum.
Last edited:
About a year ago, our group from the MD / VA / DC / PA area had a competition for an amp based on 6V6's for under $200. The chassis had to come from Ikea. The winning entry cost less than $150.
6V6 Entries
We all agreed that a 6V6 wired as a triode was really good.
ray
6V6 Entries
We all agreed that a 6V6 wired as a triode was really good.
ray
Wow guys! thanks for all the ideas to stir around my brain. I think I've found the solution:
Bridge rectifier and a single 1h 150mah choke from edcor
If I use the power supply from here (but leave my heaters AC):
using a dual jj 50+50uf / 500v cap and a 220k 5w resistor (is 5 watt enough?).
This should put me around 200$ before shipping, tubes, and case and I can deal with that. does this sound like a decent idea?
I just need to find two 10w 1.3k resistors!
Bridge rectifier and a single 1h 150mah choke from edcor
If I use the power supply from here (but leave my heaters AC):
An externally hosted image should be here but it was not working when we last tested it.
using a dual jj 50+50uf / 500v cap and a 220k 5w resistor (is 5 watt enough?).
This should put me around 200$ before shipping, tubes, and case and I can deal with that. does this sound like a decent idea?
I just need to find two 10w 1.3k resistors!
Last edited:
I seem to be suffering from cranio-rectal syndrome, sorry. The massive 2X "12" V. filament trafo I previously mentioned is inappropriate. A look at the 6EM7 data sheet shows a 925 mA. heater draw. Wired in series, 2 tubes draw (sic) 925 mA. The 2X "12" V./1.8 A. Triad VPS24-1800 (Allied stock # 967-8019) is appropriate and costs less. Regulation effects should keep the actual voltage within 5% of the nominal 12.6 V., for 2 tubes in series.
BTW, mount a pair of ferrite beads on the wires leading to the heaters close to the filament trafo. The beads keep sonic crud from sneaking into the signal circuitry via the heaters. Large value cap. I/P filters actually generate some "hash".
Regulation effects should keep the actual voltage within 5% of the nominal 12.6 V., for 2 tubes in series.BTW, mount a pair of ferrite beads on the wires leading to the heaters close to the filament trafo. The beads keep sonic crud from sneaking into the signal circuitry via the heaters. Large value cap. I/P filters actually generate some "hash".
If "cheap" is the target get ten, one watt, 13k resistors. Wire the whole mess up in parallel. Try to keep them spread out so the heat can dissipate a little.
MOS2CT52R133J KOA Speer Metal Oxide Resistors
If the Simple SE doesn't grab you, build something else, but given the choice of a 6EM7 or a 6V6 in triode, the 6V6 wins easy. 6V6's are somewhat trendy since they fit into many guitar and HiFi amps, so they can be too expensive for a budget amp. Use a 6EZ5, they can still be found for $1 or $2 each. You still need a suitable driver tube. I use the 12AT7, but some prefer other tubes like the 12AY7, 6GC7 or a Russian dual triode. Want a single tube per channel but twice the power of a 6EM7. Use a 6LU8 or 6LR8. Odd socket but they are out there. Tubes and sockets are cheap too.
I have built all of them.
The 6EM7 amp was just an experiment and I did wind up using the design as a driver in another project.
The Spud SE was built using a 6LR8. Another member built a very similar design with the 6LU8. That one sounded pretty good and had way more grunt than the 6EM7. The tube is twice as big, it just makes more sound. It is still around here somewhere. Search the forums for "Spud Anyone" for the details.
The SSE with 6V6 got built as an experiment. I put it together played with it for a while, then took it apart......then put it back together again. I liked it enough to keep it around but the Tubelab SE with 45's and Electra Print OPT's will kick its but (but you cant make that one for cheap). THe 6V6 SSE is still around with 6EZ5's in it, but it is temporarilly missing its OPT's since I needed them for an experiment.
Either way the cheapest iron for quality sound in the 1 to 4 WPC range goes like this.
The power transformer I use is the Allied 6K56VG. It costs $46 now but the Hammond 270FX may be cheaper in Canada. Either of these will get you about 320 volts with a tube rectifier and a bit more with SS diodes. Most 6V6GT's and all 6LR8's are happy with the 345 or so volts you will get with SS.
Use Edcor XSE15-8-5K OPT's. The only reason not to use them is ugliness. They sound excellent if driven by a triode and operated under 5 watts. The frequency response will go from about 30 Hz to over 30 KHz depending on tube choice. Saturation is not an issue below 5 watts.
Use a cheap Triad choke like the C-24X (about $8 at Allied). This brings the total iron budget to about $95 USD. These are the same components that I have in my 6V6 SSE.
Triode wired 6V6 family tubes are very nice. Locktal based 14C5s are dirt cheap, for good NOS. You can buy 'em from RES for $3 each.
The $11.41 Triad N-68X (Allied stock # 967-9502) is "meaty" enough to energize a stereoblock SET amp based on 6V6 family tubes. The $15.04 Triad VPL24-1100 (Allied stock # 967-2422) takes care of filament power and B+ boost. The $7.74 Triad C-24X (Allied stock # 967-1004) filter choke completes the power "iron" set. As I stated previously, the Greinacher doubler is TOUGH to beat, when low cost/high competence is needed. All of $34.19 is the outlay for power magnetics.
George (tubelab) mentioned Edcor O/P trafos. Hammond's 125ESE is another possibility.
If this sort of project is of interest, check this thread out.
The $11.41 Triad N-68X (Allied stock # 967-9502) is "meaty" enough to energize a stereoblock SET amp based on 6V6 family tubes. The $15.04 Triad VPL24-1100 (Allied stock # 967-2422) takes care of filament power and B+ boost. The $7.74 Triad C-24X (Allied stock # 967-1004) filter choke completes the power "iron" set. As I stated previously, the Greinacher doubler is TOUGH to beat, when low cost/high competence is needed. All of $34.19 is the outlay for power magnetics.
George (tubelab) mentioned Edcor O/P trafos. Hammond's 125ESE is another possibility.
If this sort of project is of interest, check this thread out.
Holy info overload! now my brain is really a pot of soup!
Eli, youre idea is definitely noted. Very interesting power supply there. I think with this amp I will stick to a more classic approach.
Mr. Tubelab, the edcor XPWR009-120 is just 5$ more and would match the GXSE10-8-5K I want to use for out out put, that is a total of 18$ more then your idea but I think it would please me more in the "looks" department. then the Triad choke you mention, perfect. Do I want two of them? one per channel? Iron budget ~$115usd and that sounds great to me.
With that I can build any of the mentioned designs be it 6V6, 6lu8 or 6em7.
I skimmed through the "Spud Anyone" thread and didnt really find a "final" schematic, I will have a look at it more closely but as it stands now, I still like the original 6EM7 idea, and the 6LU8/6LR8 ideas. (something about the short stubby tubes I guess?)
Eli, youre idea is definitely noted. Very interesting power supply there. I think with this amp I will stick to a more classic approach.
Mr. Tubelab, the edcor XPWR009-120 is just 5$ more and would match the GXSE10-8-5K I want to use for out out put, that is a total of 18$ more then your idea but I think it would please me more in the "looks" department. then the Triad choke you mention, perfect. Do I want two of them? one per channel? Iron budget ~$115usd and that sounds great to me.
With that I can build any of the mentioned designs be it 6V6, 6lu8 or 6em7.
I skimmed through the "Spud Anyone" thread and didnt really find a "final" schematic, I will have a look at it more closely but as it stands now, I still like the original 6EM7 idea, and the 6LU8/6LR8 ideas. (something about the short stubby tubes I guess?)
I have used the Triad N-68X too. In fact you can turn it around and get a 230 volt secondary which can be bridge rectified. There is a Mouser 6.3 volt transformer that can be used for the heaters and it is cheaper (don't remember the #).
I havent tried the 125ESE. I have used the 125CSE which is cheaper. The 125CSE and the Edcor XSE15-8-5K both sound similar and are suitable for this project. The Edcor has UL taps but only a single speaker tap. The Hammond has no UL taps but multiple speaker taps. The UL tap may come in handy if the 6LU8 / 6LR8 is used. Engaging the UL mode with a switch or jumper gives the option of cranking out 5 to 10 watts (depending on B+ voltage) is a possibility.
If it fits your budget, use it. It has more current capability and bigger is usually better.
I mentioned the C-24X choke because it is cheap and works better than a resistor. I have used them in SSE's that were space limited. If the budget supports 2 of them then the better choice would be 1 C-14X because it is a 6 Henry choke. You could also use 2 (one for each channel) C-7X chokes but then an extra cap in needed and I doubt that you could hear the difference unless you have super sensitive speakers.
I don't think I ever drew up a complete schematic since Kegger posted his schematic in post #25 and it is virtually identical to mine. I think there were some minor differences in resistor values which I think I explained somewhere. I don't have an Audiokarma account so I heven't looked at their builds but there are only so many ways to build a SE amp. The 6LU8 and the 6LR8 tubes are identical inside the only differences are the number of pins. I chose to use the 9 pin version because the 6LR8, the 6KY8 and the 6GF7 will all plug into the same amp. Guess what the 6GF7 is. It is a dual dissimilar triode much like the 6EM7. So if you build a 6LR8 amp you can plug in a 6GF7 if you dont run the B+ too high. The 6LU8 12 pin tube also has some pin compatible choices which night have been mentioned.
Yes, but the heater transformer and the sockets are budget breakers. You also need a lower impedance OPT. I dont think it will come alive on the 30 to 50 mA of current that the mentioned tubes run at, so a bigger power transformer is needed. I got some of them somewhere, but my cheap Ebay socket fried after a few hours of playing around with it.
You really should consider using Triad iron for the power supply. Allied has a Canadian operation so shipping is quick and reasonably cheap.
I wouldn't get too excited about the 10W resistors- justradios (Dave Cantelon in Toronto) has 1k2 10W @ 79 cents each. Good Canuck source for caps and resistors.
I wouldn't get too excited about the 10W resistors- justradios (Dave Cantelon in Toronto) has 1k2 10W @ 79 cents each. Good Canuck source for caps and resistors.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.