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Oh yeah another SSE build

After much reading and internal debate I am going to try the following SSE build


Power - Antek AS-2T350 (350-0-350)

Ouput - Edcor GXSE15-8-5K
Rectifier - solid state only


Tubes - JJ EL34L
Choke - Triad C-14X
Motor Run Cap - Pingcon CBB65A 100uf 450VAC


All other parts per standard BOM published on the Tubelab website. I do have a range of cathode resistors from 470 - 680 ohm at hand if need be.



I am very much new to this so will have many questions as I go along. First question of course does any of my choices present issues that will require solutions outside the standard build documentation? I decided to not follow the most standard build by using a toroidal power transformer and opting for ss rectification just because it appealed to me. End goal is to have an amp that will push my 4" full rangers from 80hz and up.
 
...an amp that will push my 4" full rangers from 80hz and up.

Cool. What drivers and enclosures? I'm currently listening to 4" Fostex FE108EZ's in Buschhorn MK II folded horns. I also have the older, discontinued FE108Sigmas, and some Radio Shack 40-1197's. I have no way to measure frequencies, but with my SSE using the same Edcor GXSE15-8-5K's I get great bass response.

Looking forward to your build.
 
Cool. What drivers and enclosures? I'm currently listening to 4" Fostex FE108EZ's in Buschhorn MK II folded horns. I also have the older, discontinued FE108Sigmas, and some Radio Shack 40-1197's. I have no way to measure frequencies, but with my SSE using the same Edcor GXSE15-8-5K's I get great bass response.

Looking forward to your build.


I have some FF105WKs in a Planet10 milliSize box supplemented by a sub.
https://www.diyaudio.com/forums/full-range/65061-range-speaker-photo-gallery-435.html#post5996520


Right now they have a 1st order filter at 120Hz but with the SSE I am thinking I'll try them without any filter at first and see how they do just using the natural roll off from the box and amp. Of course that is a ways away, need to built this thing first. Glad to hear the Edcor GXSE15s do the job. I plan to put mine to the test :)
 
I am trying to get an estimate of the B+ voltage using the 350-0-350 transformer and solid state rectifier. I have the IXYS DSEI 20-12A diodes. Using PSUD II software to model but these diodes are not in the database. However the original spec DSEI 12-12A diodes are. If I run the simulation with those I get ~447 volts. Is this getting me close or are the 20-12A diodes different enough to warrant trying to create a new model?
 
I am trying to get an estimate of the B+ voltage using the 350-0-350 transformer and solid state rectifier. I have the IXYS DSEI 20-12A diodes. Using PSUD II software to model but these diodes are not in the database. However the original spec DSEI 12-12A diodes are. If I run the simulation with those I get ~447 volts. Is this getting me close or are the 20-12A diodes different enough to warrant trying to create a new model?


After doing more research it looks like ~440 volts of B+ is a reasonable expectation. While I did not build a new model in PSUD II it looks like any of the like FRED models available give similar results. Also search of real world results posted seem to support this. I'll be sure to post the actual value when I get there.


For the cathode resistor if I am safe in extrapolating from the Tubes and Applications data on the Tubelab website I think I will go with a value of 620 ohm for use with my EL34s since my voltage will be slightly lower than the standard 450. It looks like a 10 volt drop would equate to around 1 amp less plate dissipation. As an option later I have a 3300 ohm resistor I can try in parallel to get me 520 ohms if I want to try a KT88.
 
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Attached is the BOM for my build. I included parts for the tube rectifier in the list since I did look them up but will not use them (they are highlighted.) Also the power transformer I choose does not have a 5V tap for tube rectifier use.
 

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Looking at the assembly instructions it seems like the alternate method for installing D1 and D2 is no longer possible with the addition of TR1 to the board. I'll go with the conventional install.
 

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Somehow I ended up with a CL-160 inrush current limiter for TR1. I looked back and noticed that all the old threads indicate a CL-140 as the part for TR1. Looking at the spec sheet it provides much less resistance at startup than the CL-140, 5ohm vs 50ohm. In my case I am not using the tube rectifier so for now I don't think it matters but I did decide to build the parts into the board just to have the option in the future. Not sure where I picked up CL-160 as the right part but I do see that another builder posted a BOM with CL-160 as well (New SSE Build from Texas.)


So question is will this part provide enough resistance to do the job or is the spec too far off to make a difference?
 
Many people survive without it, so it should be ok. The important thing is that it is either on or off. Some of the specs for those NTC varistors have operating currents in the middle of the expected range, or after, so they could have a varying affect in usage. Not so critical in an SSE where the current ought not to vary so much.

I can see you are building on one side of the board - have you considered how it will be finally installed in a case? I built my first SPP on one side, but it would have been more flexible to have had the tubes on one side so I could have had the tubes exposed on a chassis.
 
Many people survive without it, so it should be ok. The important thing is that it is either on or off. Some of the specs for those NTC varistors have operating currents in the middle of the expected range, or after, so they could have a varying affect in usage. Not so critical in an SSE where the current ought not to vary so much.




In looking at the datasheet for the CL-160 the max steady state rating is more than double the CL-140 2.8A vs 1.1A. Also the max current is far higher at 64A vs 6A. I just don't know how to determine if in this application the CL-160 will heat up enough to do it's job or do I basically just have a 5ohm resistor in circuit now?


I can see you are building on one side of the board - have you considered how it will be finally installed in a case? I built my first SPP on one side, but it would have been more flexible to have had the tubes on one side so I could have had the tubes exposed on a chassis.


I put a lot of thought into topside vs bottom side install of the capacitors, semiconductors, and connectors. I decided that I will design the chassis with a fixed bottom plate and removable top. I anticipate that the amp will be heavy and servicing would be easier if I don't have to flip it over. The tubes will poke out somewhat from the chassis but removing them will require the top plate to come off. However I will make top plate removal easy.
 
Attached is the BOM for my build. I included parts for the tube rectifier in the list since I did look them up but will not use them (they are highlighted.) Also the power transformer I choose does not have a 5V tap for tube rectifier use.


Updated BOM for my build, corrected some errors and added changes. Most notably updated TR1 to correct Cl-140 inrush limiter.


Mods - is there a way to delete the earlier BOM I posted? Would hate to have anyone use it and get the wrong parts.
 

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Mods - is there a way to delete the earlier BOM I posted? Would hate to have anyone use it and get the wrong parts.

I copied the BOM in post #12 and pasted it into post #6. If I did it right they should both be the same now.

I just don't know how to determine if in this application the CL-160 will heat up enough to do it's job or do I basically just have a 5ohm resistor in circuit now?

It won't hurt anything, but it probably won't do much either. Even the CL140 doesn't get hot enough, since it's minimum current is 200 mA. The current pulses are high enough to make a CL140 into a 10 ohm resistor or so after a minute or two, and slightly lower if it's inside a hot amp.
 
I copied the BOM in post #12 and pasted it into post #6. If I did it right they should both be the same now.



It won't hurt anything, but it probably won't do much either. Even the CL140 doesn't get hot enough, since it's minimum current is 200 mA. The current pulses are high enough to make a CL140 into a 10 ohm resistor or so after a minute or two, and slightly lower if it's inside a hot amp.


Thanks George. The BOM in post #6 is the same.


With the CL160 the minimum current is 800mA. So yes it looks like it is the same as if I installed a regular 5 ohm resistor.
 
I had a similar layout but put the toroid under the top plate, where you have your choke. Then you’d have more room for your OPTs, and maybe you could fit the motor run capacitor vertically.


With the layout as shown I would have the toriod under the top plate along with the cap and choke. The tubes and OPTs would partially stick out. The plate everything is on is 12" x 12" and would serve as the bottom plate of the chassis.



I tried moving the toroid up front but it becomes too tight of a squeeze. I would need to have it partially or fully above the top plate to make it work. I could move the cap above the choke and mount it laying down on the top plate. Question is would moving the cap so I don't need to route the OPT wires over it give me better audio performance?