I am starting on a new project. Two millimeter steel chassie, and now I am looking for a schematic...Is this an ok choice?
I'd say it all depends what budget do you have, what targets in output power, what kind of speakers you have or planning to buy etc. In general single-ended designs like the one in your post are simple, have lower power output and require a careful power supply design to avoid hum, and costly output transformers. Push pull designs, (great for 6L6 tubes!) require more components, but you gen more output power and cheaper output transformers. Just pick your poison 🙂
My opinion? Start with a push-pull. Check Tubelab's SPP here, it is very popular, relatively cheap, well regarded, and a ton of support here for your build.
My opinion? Start with a push-pull. Check Tubelab's SPP here, it is very popular, relatively cheap, well regarded, and a ton of support here for your build.
Agree with jcalvarez alternatively you also can take in account to parallel tubes in single ended design, that lower the distortion and double the power....all the best
I am using an El84 se, triode wired now. Probably 1,5 watts Class A? So speakers are no option.. I have a pair of Klipsch RP-160M. My question are about the schematic above. I will use Hammond 125 series on the output and Hammond 370HX and some Hammond Chokes in the power. I have built ten different amp, single ended, with Hammond 125 SE output transformers and I love them. Have anybody seen this schematic before, built an amp from this schematic? Yes, I have seen Tubelabs Se amp, but I have all the tubes for this amp. I do not want to change the construction, because I only need 2-6 Watts...
The schematic is really difficult to see, do you have a better quality screenshot?
Anyway, it is a pretty standard schematic, it will work. I can't see very well all component values though.
HIFI EXQUiS is a well known company in Aliexpress, they do decent stuff.
Anyway, it is a pretty standard schematic, it will work. I can't see very well all component values though.
HIFI EXQUiS is a well known company in Aliexpress, they do decent stuff.
SE pentode with global NFB might not be the first choice for a sweet sound but it sure will work.
Steel Chassis?
I feel sorry for you.
1. Steel chassis will transfer the magnetic fields from the Air-gapped choke, and the Power Transformer to . . . the Air gapped output transformer.
Hum, Hum.
2. Hard to drill, use chassis punch, etc.
2. The B+ shows Both a solid state bridge, and a tube rectifier.
The schematic does not have enough detail to show what is connected to what.
I feel sorry for you.
1. Steel chassis will transfer the magnetic fields from the Air-gapped choke, and the Power Transformer to . . . the Air gapped output transformer.
Hum, Hum.
2. Hard to drill, use chassis punch, etc.
2. The B+ shows Both a solid state bridge, and a tube rectifier.
The schematic does not have enough detail to show what is connected to what.
This time I want to build a steel chassis. A friend of mine has access to a machine where you insert an iron plate, a PC feeds the machine with information, the machine starts making the chassis. All holes are therefore already made. Am I perhaps doing a stupid thing to make a chassis out of steel? I do not know. Wasn't there a lot of steel used in the past? Will use a rectifier bridge. I'll see if I can find a clearer schematic. Thanks for the feedback
There is a steel chassis and a 2mm steel chassis. Use a combination lock in stead of fixing screws for the bottom plate, and you can also use the amp to keep your valuables safe.
I get chassis plates cut to size with all the holes drilled (using water jets) at a metal plate specialist, and they use 3mm aluminium. Isn't that an option for you too?
I get chassis plates cut to size with all the holes drilled (using water jets) at a metal plate specialist, and they use 3mm aluminium. Isn't that an option for you too?
My first experience with a steel chassis . . .
I turned the amplifier on, and Immediately I heard hum in the loudspeakers;
long before the rectifier tube, the input tubes, and the output tubes had a chance to warm up.
The power transformer and the single ended air gapped output transformers do not need time to warm up; they instantly have magnetic field coupling through the steel chassis.
Your Mileage May Vary
Just saying
I turned the amplifier on, and Immediately I heard hum in the loudspeakers;
long before the rectifier tube, the input tubes, and the output tubes had a chance to warm up.
The power transformer and the single ended air gapped output transformers do not need time to warm up; they instantly have magnetic field coupling through the steel chassis.
Your Mileage May Vary
Just saying
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Aluminium is a good option but I also have access to a CNC machine and I must use steel because the chassis is being cut from a unused part of the panel that would othervise go to scrap. I suggest to ask if 1mm is available, because 2mm is heawy and it is difficult to manually drill extra holes if you ever have the need. You probably will, unless you are doing a 1:1 copy of an already existing product. The magnetic coupling is a issue but there are mitigations. I use a clear plastic sheet under the transformers (safety ground is still ensured by the mounting screws), and there must be extra space between the power transformer + filter choke and the output transformers; more than I can see on the product you referenced. It is useful to make a test to find the best orientation.
I have build tubeamps for 30 years. No SE amps with Steel chassis, but I think I build a PP amp around 1990?, and I do not remember if there Were any hum? Should I throw the Steel chassis and use alu instead? There is no hope!?
A good choice & almost bullet proof. As always, the choice of OPT will set a limit on performance.
Just needs a steady hand & good soldering, no dry joints. 👍
And much for myself. Always Hammond Steel & never a problem caused by that.
But the OPT & PS iron need to be reasonably separated. And the lams perpendicular to each other. 👍
I use steel chassis with no problems, I like the strength of steel and find it OK to work with.
I normally use a piece of G10/FR4 as an insulator/spacer between the steel chassis and the transformer, I also insulate 3 of the four mounting screws and have one screw/nut grounding one corner only to the chassis. I have found insulating the 4 bolts holding the bell ends on the transformers is also helpful; insulating the bolts can help the frequency response of some output transformers and the radiated B field of some power transformers.
The transformers should be mounted as in post #17 by Jhstewart9.
I'm building an amplifier to use with my computer using a steel chassis at the moment and don't expect any problems; There is a shelf above my PC monitor that house a couple speakers and a small tube amp (SE 6P1P) simply because it looks cool, the plan is to have a SE 807 amp using tubes designed before WW2 simply because I can.
I normally use a piece of G10/FR4 as an insulator/spacer between the steel chassis and the transformer, I also insulate 3 of the four mounting screws and have one screw/nut grounding one corner only to the chassis. I have found insulating the 4 bolts holding the bell ends on the transformers is also helpful; insulating the bolts can help the frequency response of some output transformers and the radiated B field of some power transformers.
The transformers should be mounted as in post #17 by Jhstewart9.
I'm building an amplifier to use with my computer using a steel chassis at the moment and don't expect any problems; There is a shelf above my PC monitor that house a couple speakers and a small tube amp (SE 6P1P) simply because it looks cool, the plan is to have a SE 807 amp using tubes designed before WW2 simply because I can.
Steel chassis can't be that bad for magnetic fields. How many amplifiers and radios were sold over the years using a steel chassis? Everything from the big living room hifi systems to Heathkit, Harman Kardon, Dynaco, McIntosh, HH Scott, etc etc. I'll give you that aluminum is much easier to work with.