I have ordered most of the parts to build an SSE.
Main idea are to use the components listed with digikey serials.
Power will be Hammond 375bx
End tube will initially be EL34, making space for KT66 och KT88.
OPT Edcor GXSE 15-8-5k
Am I on deep water if I skip the choke? I have ordered a 150Ohm 5W resistor and a 120Ohm varistor, my idea is to use the varistor unless it has mayor negative drawbacks.
Another issue: I tried to save some money and did not order Auricaps. How big difference can I expect with Auricaps vs Blocked
Main idea are to use the components listed with digikey serials.
Power will be Hammond 375bx
End tube will initially be EL34, making space for KT66 och KT88.
OPT Edcor GXSE 15-8-5k
Am I on deep water if I skip the choke? I have ordered a 150Ohm 5W resistor and a 120Ohm varistor, my idea is to use the varistor unless it has mayor negative drawbacks.
Another issue: I tried to save some money and did not order Auricaps. How big difference can I expect with Auricaps vs Blocked
You don't need a choke. The SSE board has a provision for a resistor instead of choke. Calculate the max idle current and calculate the dissapated power. Double it and that is a good size.
Ok, R1 are an alternative to a choke. How do I calculate the max idle current? Can I use Ohms law to calculate the dissipated power?
On this page does Gorge mention a inlines current rush limiter. Is this a replacement for R1 or is it a complement?
Tubes and Applications | Tubelab
I'm all new to tube amps and it was a long time since I worked with AC circuits. Trying to collect all the information I need in advance, not after I burn something.
On this page does Gorge mention a inlines current rush limiter. Is this a replacement for R1 or is it a complement?
Tubes and Applications | Tubelab
I'm all new to tube amps and it was a long time since I worked with AC circuits. Trying to collect all the information I need in advance, not after I burn something.
Attachments
The series resistor in place of the choke will dissipate more than just the power from its DC voltage drop.
It will also dissipate power due to the AC ripple voltage that will drop across it. To determine that,
measure the ripple voltage with the resistor in place. The peak to peak ripple voltage divided by two
will be approximately the average ripple voltage. Then the total power dissipated in the series resistor
will be: (derate the resistor power rating by 3 to 5 times).
Presistor.total = Pdc + Pav.ripple
Presistor.total = (Vdc.drop)^2 / R + (Vav.ripple)^2 / R
It will also dissipate power due to the AC ripple voltage that will drop across it. To determine that,
measure the ripple voltage with the resistor in place. The peak to peak ripple voltage divided by two
will be approximately the average ripple voltage. Then the total power dissipated in the series resistor
will be: (derate the resistor power rating by 3 to 5 times).
Presistor.total = Pdc + Pav.ripple
Presistor.total = (Vdc.drop)^2 / R + (Vav.ripple)^2 / R
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Or one could simply put a 150 ohm 5 watt "cement" or "coffin" resistor in for R1 and forget about it. That's what's in most non choke amps. You want a choke, or a resistor, not both. Do not install R1 if you are using a choke.
You don't need a choke in the SSE, but you might want one. A choke does a better job of filtering out hum than a resistor. If you are using inefficient speakers, you might not notice a few mV of hum. Connect that same amp up to 106 dB Lowther horns and you will hear it from across the room.
You can build the amp without the choke, and add it later if hum is a problem. Just be sure to leave some room on the chassis for a choke if this is your plan, then remember to remove R1 if you do add a choke later.
The inrush current limiter is an optional component that could be wired in series with the line supply to the power transformer. It slows down the initial surge of current when the amp is first switched on to make life easier on the tubes and caps. After the first 30 seconds or so, it does nothing.
You listed your chosen power transformer as a Hammond 375BX. I don't find it listed anywhere, but the 375X is an 800 volt transformer which is too much for an SSE. The usual transformer for this board is the 374BX.
There are three components that are not documented on the web site instructions. D3 and D4 are ordinary 1N4007 or UF4007 diodes. TR-1 is a CL140 inrush current limiter. These parts were added after around 2012 to improve the life of the rectifier tube at a time when the quality of some new production tubes was pretty bad. Be sure to order them with all the other parts.
You don't need a choke in the SSE, but you might want one. A choke does a better job of filtering out hum than a resistor. If you are using inefficient speakers, you might not notice a few mV of hum. Connect that same amp up to 106 dB Lowther horns and you will hear it from across the room.
You can build the amp without the choke, and add it later if hum is a problem. Just be sure to leave some room on the chassis for a choke if this is your plan, then remember to remove R1 if you do add a choke later.
The inrush current limiter is an optional component that could be wired in series with the line supply to the power transformer. It slows down the initial surge of current when the amp is first switched on to make life easier on the tubes and caps. After the first 30 seconds or so, it does nothing.
You listed your chosen power transformer as a Hammond 375BX. I don't find it listed anywhere, but the 375X is an 800 volt transformer which is too much for an SSE. The usual transformer for this board is the 374BX.
There are three components that are not documented on the web site instructions. D3 and D4 are ordinary 1N4007 or UF4007 diodes. TR-1 is a CL140 inrush current limiter. These parts were added after around 2012 to improve the life of the rectifier tube at a time when the quality of some new production tubes was pretty bad. Be sure to order them with all the other parts.
Great answare!
150 Ohm 5W are now installed @ R1. Choke is not in any plans at the moment. Will try to remember to cut of R1 if I change my mind.
D3 &D4: can't find it in the scheme, where to put them?
TR-1: I Have 2pc of CL-90, are those sufficient?
375BX are a typo, read 374BX 🙂
150 Ohm 5W are now installed @ R1. Choke is not in any plans at the moment. Will try to remember to cut of R1 if I change my mind.
D3 &D4: can't find it in the scheme, where to put them?
TR-1: I Have 2pc of CL-90, are those sufficient?
375BX are a typo, read 374BX 🙂
Found D3, D4 and TR1 on the PCB. It ca be that I have the diods hiddens i a box, otherwise will I order then together with some hardwqre as connectors for speakers etc.
