Need a little help to finish my sse...
Hi everybody!
After waiting for almost 9 months I'm finally ready to build my SSE.
However, I have a question about the inrush current limiter (the one between mains and trafo primary), Here in Europe, it's a real pain to find a 120R / 2A CTN, mouser, digikey and farnell stocks them, but i'm reluctant to spend $26 of shipping charges for a $1.8 part. However, I found a 220R / 3A ntc locally:
Here the datasheet (model MS22 22103) http://www.tme.eu/fr/Document/d51f023d01f7d8fc654828c79a3fef8c/MS22-22103-AMP-datasheet-2012.pdf
Will this work?
I too have some cl-60 (10R / 6A) and Epcos 33 (33R / 1.3A) on hand in case...
As for the amp itself, here the parts I've selected (with some questions):
Power transformer: Hammond 374BX (primary wired for 240 mains, measured at 225Vac from my wall plug)
Output trafos: Edcor CXSE25-5-8
Choke: Hammond193H (5H, 200mA, 65R, 600V)
Additional PSU cap: 80uf 450V motor start/run cap (Senju CBB65)
Rectifier tube: Shuguang 5AR4
Driver tube: Tungsram 12at7
Power tubes: Reflector 6P3S-E
Cathode resistor value: wirewound 680R / 5W Q: Shall a 820R be more adequate for the 6P3S-E?
C11/C21 : Cornell Dubilier CDE 0.22uf 1000V Q: I also have some russian PIO but they are rated at 400V witch maybe a little too low?
C12/C22: Panasonic FC 1500uf / 50V
As for the main fuse, given that the 374BX is rated at 198VA, I project to use a 1A fuse (198/240=0.825), but I should maybe use a little higher rated one (1.250A?)
Do you see something wrong on this list?
PS: Thanks a lot to George for his tremendous work and dedication
Hi everybody!
After waiting for almost 9 months I'm finally ready to build my SSE.
However, I have a question about the inrush current limiter (the one between mains and trafo primary), Here in Europe, it's a real pain to find a 120R / 2A CTN, mouser, digikey and farnell stocks them, but i'm reluctant to spend $26 of shipping charges for a $1.8 part. However, I found a 220R / 3A ntc locally:
Here the datasheet (model MS22 22103) http://www.tme.eu/fr/Document/d51f023d01f7d8fc654828c79a3fef8c/MS22-22103-AMP-datasheet-2012.pdf
Will this work?
I too have some cl-60 (10R / 6A) and Epcos 33 (33R / 1.3A) on hand in case...
As for the amp itself, here the parts I've selected (with some questions):
Power transformer: Hammond 374BX (primary wired for 240 mains, measured at 225Vac from my wall plug)
Output trafos: Edcor CXSE25-5-8
Choke: Hammond193H (5H, 200mA, 65R, 600V)
Additional PSU cap: 80uf 450V motor start/run cap (Senju CBB65)
Rectifier tube: Shuguang 5AR4
Driver tube: Tungsram 12at7
Power tubes: Reflector 6P3S-E
Cathode resistor value: wirewound 680R / 5W Q: Shall a 820R be more adequate for the 6P3S-E?
C11/C21 : Cornell Dubilier CDE 0.22uf 1000V Q: I also have some russian PIO but they are rated at 400V witch maybe a little too low?
C12/C22: Panasonic FC 1500uf / 50V
As for the main fuse, given that the 374BX is rated at 198VA, I project to use a 1A fuse (198/240=0.825), but I should maybe use a little higher rated one (1.250A?)
Do you see something wrong on this list?
PS: Thanks a lot to George for his tremendous work and dedication
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Cowenko,
Nothing wrong with the OPT and choke. If you were in the process or ordering, I would have suggested to get the choke from Edcor - might have resulted in some savings on postage.
The supplemental capacitor has to be motor run cap, not a motor start cap.
In fact, being in europe, ordering the trafos directly from Edcor USA was not an option (in regard to shipping charges and custom fees), I however been able to find a european company selling them (Edcor OPT), but not their chokes nor the appropriate Power Trafo, that's why I ended picking Hammond power and choke.
As for the CAP, I know that I need a run type, a start cap would much certainly fail big time if exposed to continuous load, however the description was confusing and given the cap as the aspect of a run cap (big metal can)...
To be safe, I ordered a new one in US, a 80uf 440V
NEW Motor Round Single Run Capacitor 80 MFD 370 440 VAC Volt Supco CR80x370R
This one shall do nicely.
I've just tested one channel (in triode mode) with 680R KR (6p3s-e tube) with 5AR4 rectifier and 12at7 driver. I put a 8R 50W dummy load resistor on the OPT output.
The Power trafo has been plugged on a lightBulb tester.
The Choke is used, but not the additional cap (as I suspect it's not a pure Run one) I'm waiting for one to arrive.
I'm using a CL-60 CTN in serial with the PT primary and a 1A slow blow fuse.
Everything seems fine, the light bulb (150W) is dimmed to faint red filament, rectifier tube and driver are giving their soft red light and warmth and 6p3s-e is glowing too (although quite faintly) and warm up. No signs of reddish plate, no trafo vibration, no burnt smell.
Now I would like to control the various voltages to check if everything is fine; can you be so kind as to tell me what and where to measure (type of measurement and location of the measure points) as well as the expected values to be found?
On the other hand, can You tell me if the CL-60 CTN (10R 6A) is sufficient as an inrush current limiter, or if I have to put an higher res one (I can find a 220R 3A)
Also, is this normal for the 6p3s-e to have that weak of a glow?
The Power trafo has been plugged on a lightBulb tester.
The Choke is used, but not the additional cap (as I suspect it's not a pure Run one) I'm waiting for one to arrive.
I'm using a CL-60 CTN in serial with the PT primary and a 1A slow blow fuse.
Everything seems fine, the light bulb (150W) is dimmed to faint red filament, rectifier tube and driver are giving their soft red light and warmth and 6p3s-e is glowing too (although quite faintly) and warm up. No signs of reddish plate, no trafo vibration, no burnt smell.
Now I would like to control the various voltages to check if everything is fine; can you be so kind as to tell me what and where to measure (type of measurement and location of the measure points) as well as the expected values to be found?
On the other hand, can You tell me if the CL-60 CTN (10R 6A) is sufficient as an inrush current limiter, or if I have to put an higher res one (I can find a 220R 3A)
Also, is this normal for the 6p3s-e to have that weak of a glow?
I have the Edcor XPWR035 power transformer and Edcor CXSE25-8-5K Output Transformers.
Like others I measure B+ on the RED primary wire of the opt usually where it
connects to the board. My B+ comes to just around 460Vdc, with your Hammond power transformer
you should get close to that, 450Vdc should be okay.
Plate voltage can be measured on the BLUE primary wire of the opt.
For inrush current limiter a CL-90 is what Tubelab recommends and what I use.
Like others I measure B+ on the RED primary wire of the opt usually where it
connects to the board. My B+ comes to just around 460Vdc, with your Hammond power transformer
you should get close to that, 450Vdc should be okay.
Plate voltage can be measured on the BLUE primary wire of the opt.
For inrush current limiter a CL-90 is what Tubelab recommends and what I use.
spendorite, Thanks a lot for your advises 
I made the measurements:
B+: red probe on r4 (witch is directly linked to red OPT primary) and black on R27 (witch is connected to the ground plate) = 423V dc
Plate voltage: red probe on Blue OPT primary, black on R17 (connected to ground plate) = 422V dc
Those seems a little on the weak side, but maybe it's due to the cl-140 witch is mounted on the board as it's the new revision board with 1N4007 diodes and CL-140 ntc (50R 1.1A)
Concerning the CL-90 I searched everywhere, and i'm stuck with mouser digikey and farnell, but the shipping charges are outrageous (except if the order exceeds the 60€, but I do not have the need for that much components).
If someone here has one CL-90 available, I would be grateful is he accepted to sell it to me.
I made a quick calculation to know if my 6p3s-E tube aren't swinged too hard:
If I trust this datasheet http://www.tubes.ru/techinfo/HiFiAudio/6p3s.html The 6P3S-E can handle 20.5W plate dissipation.
In my case: 36.4/680*(422-36.4)=20.44W -> I'm dead on specs (on the high side though), so in my case, the "relatively" low B+ voltage seems to serve my tubes fine.
I made the measurements:
B+: red probe on r4 (witch is directly linked to red OPT primary) and black on R27 (witch is connected to the ground plate) = 423V dc
Plate voltage: red probe on Blue OPT primary, black on R17 (connected to ground plate) = 422V dc
Those seems a little on the weak side, but maybe it's due to the cl-140 witch is mounted on the board as it's the new revision board with 1N4007 diodes and CL-140 ntc (50R 1.1A)
Concerning the CL-90 I searched everywhere, and i'm stuck with mouser digikey and farnell, but the shipping charges are outrageous (except if the order exceeds the 60€, but I do not have the need for that much components).
If someone here has one CL-90 available, I would be grateful is he accepted to sell it to me.
I made a quick calculation to know if my 6p3s-E tube aren't swinged too hard:
If I trust this datasheet http://www.tubes.ru/techinfo/HiFiAudio/6p3s.html The 6P3S-E can handle 20.5W plate dissipation.
In my case: 36.4/680*(422-36.4)=20.44W -> I'm dead on specs (on the high side though), so in my case, the "relatively" low B+ voltage seems to serve my tubes fine.
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I think your B+ of 423Vdc should be okay although with your Hammond power
transformer you should probably get closer to 450V. It should be sufficient to
drive power tubes like KT88 and 6550 but maybe not to their maximum output
power.
The cl-140 and diodes D3 and D4 should not affect your B+ they are just there
to give some protection to current production rectifier tubes.
Sorry, I do not have any spare CL-90 to offer.
transformer you should probably get closer to 450V. It should be sufficient to
drive power tubes like KT88 and 6550 but maybe not to their maximum output
power.
The cl-140 and diodes D3 and D4 should not affect your B+ they are just there
to give some protection to current production rectifier tubes.
Sorry, I do not have any spare CL-90 to offer.
I don't really get why I find only 423Vdc B+, as I have measured 450Vdc the day before (but with one channel active only and through R4).
Maybe my mains fluctuates in power at certain hours (last time I measured the mains they where at 225Vdc), The thing Is, it seems not possible to wire the hammond power trafo primary to 230V so I'm stuck with 240V (220V would be a little too low), I must loose some power in the process.
I'll take measure of the mains, HT secondaries and B+ voltage as soon as I come back home.
Maybe my mains fluctuates in power at certain hours (last time I measured the mains they where at 225Vdc), The thing Is, it seems not possible to wire the hammond power trafo primary to 230V so I'm stuck with 240V (220V would be a little too low), I must loose some power in the process.
I'll take measure of the mains, HT secondaries and B+ voltage as soon as I come back home.
So, after looking at the primary windings of the Hammond a little closer, I've been able to wire it for 230V mains---> big bump in output voltage
So, here the measurements:
-Mains: 228V AC
-Trafo secondaries (without load):
HT1+CT = 396.1V AC
HT2+CT = 396.4V AC
HT = 793V AC
5V = 5.29V AC
6.3 = 6.81V AC
B+ = 454V DC
Plate = 445V DC
VK = 36V DC
Plate Dissipation = 36/680*(445-36) = 21.6W
That's maybe a little violent for the 6P3S-E, I shall perhaps substitute the 680R RK for some 820R res.
So, here the measurements:
-Mains: 228V AC
-Trafo secondaries (without load):
HT1+CT = 396.1V AC
HT2+CT = 396.4V AC
HT = 793V AC
5V = 5.29V AC
6.3 = 6.81V AC
B+ = 454V DC
Plate = 445V DC
VK = 36V DC
Plate Dissipation = 36/680*(445-36) = 21.6W
That's maybe a little violent for the 6P3S-E, I shall perhaps substitute the 680R RK for some 820R res.
Thanks a lot zman01,
Well yes I already have read through the George's calculation sheet as well as Russ spreadsheet Tubelab Simple SE – Construction – metaruss
Because I want to make a RK selector within my amp to be able to switch between tubes easily.
And right, Plate voltage rise according to RK value
, but it doesn't explain the bump in B+ voltage.....In fact I forgot one data from my previous measurements:
IK = 45mA
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Hi everybody!
Well, my SSE is up and running, with it's RK selector (thanks goes to Spendorite for checking out my wiring diagram )
It's in it's case (will post a picture later) and I run it with EH KT88 (selecting 560R RK on my selector).
Until now I was running it in triode mode (no CFB or/and UL) without problems, the amp is dead silent in this mode (my ground scheme is the one recommended by george, running the board ground from one RCA cold to the main ground point).
But today I made the selectors for CFB mode and Triode/UL switch. Here began the humming problem.
In UL+CFB mode I get a Low hum (surely 50hz), whether there's a jack connected or not on inputs, the same at all volume levels, so the problem comes from the amp.
The hum is relatively faint but can be clearly heard from listening position without music
Thinking, maybe the long wires needed for wiring the selector induced the hum, I decided to make a direct connection for all the modes, here the results:
Triode Mode = No hum at all
UL+CFB = Low hum
UL (no CFB) = Low hum (less than UL+CFB)
Triode + CFB = very faint Low hum
Do you have an idea of where do the hum comes from?
For info, here's my setup:
PWR trafo: Hammond 374BX
OTs: Edcor CXSE25-5-8
Supplemental cap: 80uf motor run cap 440V
Choke: Hammond 193H
C11/C21: Russian PIO KY04 0.22uf 650V
Rectifier Tube: Shuguang 5AR4 (will soon try a Svetlana 5C3S rectifier)
Driver Tube: Tungsram 12at7 (will be soon replaced with an Amperex E180CC)
Power tubes: EH KT88
I use CL90 on PWR trafo primary
The amp is driving a pair of fullrange BEYMA 12GA50 (8R, 102db).
Well, my SSE is up and running, with it's RK selector (thanks goes to Spendorite for checking out my wiring diagram
)It's in it's case (will post a picture later) and I run it with EH KT88 (selecting 560R RK on my selector).
Until now I was running it in triode mode (no CFB or/and UL) without problems, the amp is dead silent in this mode (my ground scheme is the one recommended by george, running the board ground from one RCA cold to the main ground point).
But today I made the selectors for CFB mode and Triode/UL switch. Here began the humming problem.
In UL+CFB mode I get a Low hum (surely 50hz), whether there's a jack connected or not on inputs, the same at all volume levels, so the problem comes from the amp.
The hum is relatively faint but can be clearly heard from listening position without music
Thinking, maybe the long wires needed for wiring the selector induced the hum, I decided to make a direct connection for all the modes, here the results:
Triode Mode = No hum at all
UL+CFB = Low hum
UL (no CFB) = Low hum (less than UL+CFB)
Triode + CFB = very faint Low hum
Do you have an idea of where do the hum comes from?
For info, here's my setup:
PWR trafo: Hammond 374BX
OTs: Edcor CXSE25-5-8
Supplemental cap: 80uf motor run cap 440V
Choke: Hammond 193H
C11/C21: Russian PIO KY04 0.22uf 650V
Rectifier Tube: Shuguang 5AR4 (will soon try a Svetlana 5C3S rectifier)
Driver Tube: Tungsram 12at7 (will be soon replaced with an Amperex E180CC)
Power tubes: EH KT88
I use CL90 on PWR trafo primary
The amp is driving a pair of fullrange BEYMA 12GA50 (8R, 102db).
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Well, after closer listening, I get a very faint hum in triode mode (need to put my ear inside the driver cone ) so I think it may possibly be a problem with the position of the Power transformer in relation the OTs.
I'll test with unplugged OTs primaries and power tubes out to find if I still get the hum. If it's the case, I'm screwed as I will have to redo my top plate
Strange as I made sure to separate the pwr transformer enough from the OTs (2.5cm) and oriented at 90°....
) so I think it may possibly be a problem with the position of the Power transformer in relation the OTs.I'll test with unplugged OTs primaries and power tubes out to find if I still get the hum. If it's the case, I'm screwed as I will have to redo my top plate
Strange as I made sure to separate the pwr transformer enough from the OTs (2.5cm) and oriented at 90°....
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