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Single Ended EL-34 build


henry4841

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About half of my dovetail cutting makes me happy. I have three saws one can use to cut dovetails. I tried using the pull cut Japanese saw to begin with. I would have to have many hours using it before I could cut decent looking dovetails with that thing. The other one is a dovetail saw that I can use somewhat better than the Japanese saw. But the one I used for many years is just a plain old backsaw. I can cut my best looking dovetails using it. Also the quickest. That Japanese saw takes a lot of sawing with those tiny teeth. Wears out an old mans arm. About half of the dovetails I cut on this case I can say I am proud of. The half when I started to use the backsaw. Still with some wood putty and sanding the others will be presentable as well. They are still hand cut dovetails that most that are not woodworkers would never see the difference. Just a woodworkers thing. 

 

 

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George, below is a picture of the round over bit I am using. Not sure of the size but the one I like to use. Also a picture of the progress made this morning. I did install the rails to hold the aluminum plate and did some more wood filling of the dovetail joints. Now I must wait for the glue to set before preceding further. All that an old man really wants to do this morning anyways. 

P1040090.JPG

P1040091.JPG

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7 minutes ago, grindstone said:

They're unique and they're exactly what retired guys are supposed to do (because there's no time for it before then).  Thanks for posting the updates.  I never did buy one of those Japanese saws and, courtesy of your report, I now know why I wont. 

My thought are those that use that thing have too much time on their hands. Takes forever and a lot of time mastering that thing. Why bother is my thoughts. I built 5 blanket chest all with hand cut dovetails and I would still be cutting dovetails if I were trying to use that saw. 🙂 

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56 minutes ago, tube fanatic said:

The ESE is my overall favorite xfmr and I have often used it even when one of the smaller members of the series would have been enough.  The FSE and GSE are terrific for the higher plate current applications.  How large is the chassis you are using to be able to accommodate the xfmrs underneath?

 

Maynard

I hope big enough. 🙂 I will get the measurements later today or in the morning. I did increase the size considerable on this build. If not enough room I am not too proud to install them on top but would rather not. I just bet the EL-34 tubes are going to sound better with these OPT's. For $20 more a pair they are going to be my go to OPT from now on. 

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15 hours ago, tube fanatic said:

How large is the chassis you are using to be able to accommodate the xfmrs underneath?

 

Maynard

I measured the plate this morning and this builds plate is 1 1/2" wider than the last build. The dimensions of the plate is 14 1/2" X 11 1/2" whereas the last build was 14 1/2" X 10". The OPT's will be installed as the last build and the length is just a little more on these transformers so I should be OK mounting them underneath since this case is 1 1/2" wider. Length is the same and an inch higher wood case, 4", for those taller transformers. 

 

I was checking for the CCS 10M45's spec sheet this morning on Mouser and did not know Mouser was out of them. I planned on using the ones already mounted on heatsinks in my present build so I did not order them along with the other items. The electronic parts shortage is still an ongoing problem for the electronic industry. Much like going to the grocery store. You buy what they have and not what you want. 

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Guys I mentioned  this amplifier is called the Tubelab SSE, simple single ended. There is no need for me to give a detail build guide on the build being that George has one better on his website with full instructions, BOM and most anything one will ever need to complete this amplifier successfully. http://tubelab.com/designs/tubelab-sse/manual/

This design came about with George and the members on diyaudio.com. I built mine probably 6 or more years ago as one of my first tube builds. I have always enjoyed the sound. This is a more common 5+ watts per channel SET. More than enough power for our Klipsch speakers. PWK said so himself in one of his videos. It is with apprehension I am fixing to tear it down when it works and sounds so good. I ordered old tubes on Ebay and Tubedepot for this build. The last few nights I have been listening to the new for me old tubes. The preamp tube was bought as used USA made 12AT7 for $10 at Tubedepot. The EL-34's are marked Marshall, a guitar amplifier. The preamp tube I have been using was a NOS RCA tube when I bought it. Sounds really good as well. But if I want to try and improve the sound and looks that is what I am going to do. Give my kin something to argue about when I am gone. Over who gets the pretty ones. 

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Update. I am not going to tear down the Tubelab SSE I have now. I had it on my workbench doing some testing and while I was looking it dawned on me that all I really need is another PS transformer and I can keep this one together. Mouser has the Allied 6K7VG that George said he has used for $54 delivered to my house. That is what I just did. Fact is I am almost positive I have a toroidal PS transformer from a previous build that would work but those things are big and ugly if put on top. 

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What circuit do you plan to use now with this new wood chassis?

 

I can share some of my schematics if you want to try something different. I highly suggest something based on the 4P1L tube because not only do my ears say it's better sounding than a 45 but many others have had similar experiences.

 

If not the 4P1L which can have some not so easy heater requirements for a "simple build" I would recommend a Triode wired 6AV5GA which will end up sounding like a 2A3 but with no hassle of powering the directly heated cathode and they are much less expensive than a 2A3.

 

Then there is the 20 watt SEP amp I'm making for Shakey but it's fixed bias and has a power drive circuit for A2 grid drive operation. Not exactly "simple" but it's not that complicated if you want something more challenging. The only issue with this design is it uses 20db of negative feedback that should be compensated properly, not an easy endeavor for the casual hobbyist amp builder.

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On 9/28/2022 at 2:58 PM, captainbeefheart said:

What circuit do you plan to use now with this new wood chassis?

 

I can share some of my schematics if you want to try something different. I highly suggest something based on the 4P1L tube because not only do my ears say it's better sounding than a 45 but many others have had similar experiences.

 

If not the 4P1L which can have some not so easy heater requirements for a "simple build" I would recommend a Triode wired 6AV5GA which will end up sounding like a 2A3 but with no hassle of powering the directly heated cathode and they are much less expensive than a 2A3.

 

Then there is the 20 watt SEP amp I'm making for Shakey but it's fixed bias and has a power drive circuit for A2 grid drive operation. Not exactly "simple" but it's not that complicated if you want something more challenging. The only issue with this design is it uses 20db of negative feedback that should be compensated properly, not an easy endeavor for the casual hobbyist amp builder.

George Anderson's SSE EL-34. Most of my parts are here. At first I was just going to take the SSE I built many years ago and take it apart, install better parts and put it in the chassis but then I thought I have most everything but the PS transformer to build a complete new amp so I ordered a PS transformer and am in the process of turning the SSE that was biased for EL-34 tubes and biasing it for the 6L6 tubes. So it will be a dedicated 6L6 amplifier and the one I am now building is going to be for a dedicated SET EL-34 amplifier. Looking at the build quality of the first SSE I would be ashamed for anyone to see the work that was done. Definitely needs tidying up better wiring and soldering. So now I have two projects going on at once.

 

 

Simple_SE_Amp_Sch_11-08.jpg

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The aluminum plate that I ordered came yesterday so I should be able to start cutting some pieces to finish the basic chassis the next few days. Still a lot of drilling and cutting holes need to be done before it will be ready to install parts and electronic components. The Hammond PS transformer should be here today so that should be everything I need to start doing some layout where I will know how and where to drill holes in the plate. The last few days I have been working on the old SSE doing some testing and biasing of it for 6L6 tubes. I missed doing electronic work while woodworking on that chassis. I like woodworking but at this stage in my life I would rather play with electronics. Less physical. 

 

I figured out how to post the schematic on the forum of this build where it is more easy to see for members. Very simple SET amplifier with the biggest difference being the 10M45S CCS circuit. Right now the 10M45S is really scarce with all the normal sources out of them. Luckily I have a pair of them in stock. Nelson Pass uses them in some of his builds so I have some extras and do not need to order any from dubious sources until they are back in stock at Mouser. 

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I have been busy working on the chassis for this build along with biasing my old SSE amp for some 6N3C, 6L6 Russian equivalents, tubes. I bought a number of those tubes when the price was really low and not that long ago. This way I will a dedicated 6L6 amplifier along with one for EL-34 tubes. I do not want to feel like I am being a showoff so I am cutting back on posting a detailed every day process of this build. One can look at my last detailed build and see pretty much the same thing I am doing now. I will post pictures when a stage has been completed and do plan to keep everyone that is interested in tube amp building informed on my ups and downs of amplifier building. I have a number of old builds that could use a redo since I like to think I could do a better job now than I did 10 years ago. So there should be more projects to follow after this one. Maybe all my grandkids will get a pretty tube amp when the day comes. 

 

One of my grandkids, 18 and starting college, just got a brand new Dodge Charger for a graduation present from his Dad. Brought it straight to my house after leaving the showroom floor. That thing has 375hp. When I was involved in hot rods years ago we considered anything over 300hp to be plenty for the street. I hope he does not "let it get away from him." That is what I heard say when I was in the car business after a customer had a wreck. 

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1 hour ago, Cicerogue said:

henry4841, have you tried any of the Veritas dovetail saws? I have the original model and it gave me great results, right away.

I like the handle. Should do a good job and I think I could like it. Going to be slower than a backsaw though with those smaller teeth. 

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I am now waiting on some 5 watt resistors from Mouser to cathode bias my 6n3c tubes I am going to use in my old SSE. With some help from Maynard and using ohms law I now think a 750 ohm cathode resistor is what I need to get 16 or so watts of dissipation in the 6n3c tubes. They are rated for 20 watts but I think that is not a safe amount for this tube. At 20 watts, what I have the tubes biased at now, the plates have some red spots which is a no no when it comes to tubes. I know approximately what the cathode to plate voltage is going to be from experience and from ohms law I am looking for 43ma of current to be run in the tube. This is how I came up with the 750ohm cathode resistor. A 650ohm resistor runs too hot and 820ohm is too cold. Those are two 5 watt resistors I have on hand which I have tried. Finding a resistor value for a circuit is something I have done very little of in my life of electronics. My thing has always been repairs of already designed circuits where one already has the values established or building an amplifier from a proven schematic. Designers are the ones that use ohms law for resistance calculations when designing a circuit. Oh occasionally I have change a value of a resistor in a circuit for some reason but not something done by most repairmen. My dealings with ohms law in the past was finding volts, amps and watts and not resistor values. Something new for me and rather fun doing something I have not done a lot of in the past. Who knows with some help I may eventually be able to design a tube amp from scratch myself. And possible it work correctly. 🙂 I would like to mention that nowadays there are some ohms law calculators online where one does not have to do the math with pencil and pen. Those with software skills also have available programs that can design circuits. TubeCad SEamp Cad is a program George Anderson used to approximate the values in his amplifier. Not something I relish in doing, TubeCad, or have a desire to do at this stage in my life but learning how to use such program would be very beneficial for some young person. No telling where it might lead. I came to my resistance values with a cheap calculator, pencil and paper and an ohms law wheel sitting in my backyard yesterday morning. Old school. Real nice have a teacher like Maynard to turn to when needed. 

 

Also did some more cutting of wood and making of metal plates for my cherry wood chassis to hold my new SSE EL-34 amplifier. It is slowly coming together a few hours of work everyday. I will show pictures when I get further along with the drilling of holes and cutting of wood for the plates. 

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