Ok. Thank you for telling me.
BUT where the heck can i get a similar one, usully they are only 230 and no center tap..
Do anybody know where to get one (for a decent price?)
For heater i was thinking, i have one 2x9V /50VA/ 1,12Ax2/ R-Core (for my old dac) Can i somehow use that? With regulator and DC maybe?
I'm not gonna use the circuit boards after this. They are just for now. I have bought Sockets for mounting in chassie for all 3 tubes so i was thinking "hard-Wired" i think you call it. I've also bought some screened ÖLFLEX powercable (2x1mm) that maybe i can use for heaters and other sensitive wirings? Then i can hook it up to the ground thus get a good shielding. Or is a twisted better?
So with this said, i will do my best to make it good and professional when i do the final. Also change rest of res to Kiwame/Takman Carbon. -I really like them 😉
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Sorry, I don't now, I make my own trafos.
For such power you don't need a separated trafo for heaters, and you will not solve the heating problem, because as I said with no load a core heats at its max.
First try to find the best place for the PT, a mu-metal wall and a new trafo can wait a little.
Edit: What is the temperature of the trafo at idle?
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I opted for a similar transformer to the one you have now, but I was looking at a Triad VPT230-110 as an alternative at one point, as it was available in the UK, and from other sources.
Point to Point wiring is good and should be simple on this circuit.
A cap across the power switch will help with pops - but make absolutely certain that it is rated for this application, they are called X1 or X2 or Y1 caps. You input power conditioner is a great idea and would allow you to use a toroidal power transformer if you replace the PT. toroidals will have no stray magnetic field so are much easier to place within the case. The triads are a good cheap brand - but the VPT230-110 would only work with a full bridge rectifier which is difficult with valves.
Tightly twisted solid core wire (relatively thin) is the best bet for AC heaters. There is a tutorial on the stickies on good heater wiring I advice reading it. Nothing fancy for this situation.
You are stuck with the Power transformer you have for the moment so find the best location for it.
Mu-Metal is a thin magnetic material used for screening, I have salvaged sheets from dead studio and test equipment. It is shinny and covered in a thick plastic film - easy to cut and bend.
Shoog
A cap across the power switch will help with pops - but make absolutely certain that it is rated for this application, they are called X1 or X2 or Y1 caps. You input power conditioner is a great idea and would allow you to use a toroidal power transformer if you replace the PT. toroidals will have no stray magnetic field so are much easier to place within the case. The triads are a good cheap brand - but the VPT230-110 would only work with a full bridge rectifier which is difficult with valves.
Tightly twisted solid core wire (relatively thin) is the best bet for AC heaters. There is a tutorial on the stickies on good heater wiring I advice reading it. Nothing fancy for this situation.
You are stuck with the Power transformer you have for the moment so find the best location for it.
Mu-Metal is a thin magnetic material used for screening, I have salvaged sheets from dead studio and test equipment. It is shinny and covered in a thick plastic film - easy to cut and bend.
Shoog
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Hi,
If I may add my 2cents, I can't help but notice that way too thick wires are being used.
The more metal the easier they pick up all kinds of noises and stray fields.
I find small diameter ( .4 to .6mm) solid core (single strand) wire easier to work with as it can easily be bend and be pushed flat against the chassis' bottom plate.
If you have wires that carry AC that need to cross, make them cross at right angles.
Ciao, 😉
If I may add my 2cents, I can't help but notice that way too thick wires are being used.
The more metal the easier they pick up all kinds of noises and stray fields.
I find small diameter ( .4 to .6mm) solid core (single strand) wire easier to work with as it can easily be bend and be pushed flat against the chassis' bottom plate.
If you have wires that carry AC that need to cross, make them cross at right angles.
Ciao, 😉
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I have no idea... but let me say like this;
music: fingervarm... guessing around 40 degress
idle: varmer, almost like i can't touch it longer than 5-10 sec. I can hold longer with my finger on top of one of the 6n3p's or the rectifier.
MY yaqin kt88 gets much hotter everywhere though...😀
blue wire is 0.75,
red is 1,5
black is 1.0
i took what i had i my shed 😉
I recently bought 0.6mm silver plated PTFE from hificollective in uk. Could that be something?
You mean signal or/and psu??
I must add that after turning the trafo up (like in pic) the preamp is quiet. I can't hear much at all in my sofa, about 2.5m away, only with ears up to tweeter there is little noise.
And it sounds really good =) all records i listen to today sounds like never before... super open, lots of details but still coherent... Bass is fun... superdry and lots of slam. Impressed.
Dynamic is there too, slam bam..got almost thrown of sofa today... this is so much better then my 1500 euros Yamaha Adventage.
And it sounds really good =) all records i listen to today sounds like never before... super open, lots of details but still coherent... Bass is fun... superdry and lots of slam. Impressed.
Dynamic is there too, slam bam..got almost thrown of sofa today... this is so much better then my 1500 euros Yamaha Adventage.
Hi,
Should be fine for signal as a twisted pair. No need for shielded wire at this level.
I often find silver plated copper wire to have a tilted frequency response towards the highs. YMMV.
Both really.
Ciao, 😉
Should be fine for signal as a twisted pair. No need for shielded wire at this level.
I often find silver plated copper wire to have a tilted frequency response towards the highs. YMMV.
Both really.
Ciao, 😉
Cutting and bending signifcantly weakens its magnetic properties so it needs to be re-annealed afterwards. DIY folk do not always realise this. It also saturates easily so only suitable for screening small magnetic fields.Shoog said:
Sooner or later you must got a new trafo.
Toroidals aren't the panacea, DC susceptibility and also stray magnetic field because manufacturers are stingy and work at almost its max magnetic induction.
What about a aluminium (2mm thick) with copper tape on outside connected to ground?
Also we should not forget about the choke. When i put that closer then 10cm/4" to tubes i got serious noise/hum/buzz. In pic it's outside the case.
To be honest, i wonder if i can get everything to fit in my chassie if i don't have PT on "top", maybe also choke.
-My idea was to mount tubes+PT on top when i bought this case.
Also we should not forget about the choke. When i put that closer then 10cm/4" to tubes i got serious noise/hum/buzz. In pic it's outside the case.
To be honest, i wonder if i can get everything to fit in my chassie if i don't have PT on "top", maybe also choke.
-My idea was to mount tubes+PT on top when i bought this case.
Dug mine out earlier, and the transformer appears to have stabilised at around 47C after 2.5 hours. Room temperature is maybe 22C. Doesn't seem to matter whether I have any input or not.
Completely stock right now, including the valves. Wired up a headphone socket to test; no hum noticed yet.
The transformer is ever so slightly different to yours. Primary is the same (0-110-220V), but the label rates the 230V winding at 0.037A, and both 6.3V windings at 1.5A. Measured voltages are a bit higher (252V and 7.15V) but then mains here is probably closer to 240V than 220V.
Don't know if that's useful at all, but I thought the different current ratings were interesting.
Completely stock right now, including the valves. Wired up a headphone socket to test; no hum noticed yet.
The transformer is ever so slightly different to yours. Primary is the same (0-110-220V), but the label rates the 230V winding at 0.037A, and both 6.3V windings at 1.5A. Measured voltages are a bit higher (252V and 7.15V) but then mains here is probably closer to 240V than 220V.
Don't know if that's useful at all, but I thought the different current ratings were interesting.
Aluminium is great to shield electric field, but not magnetic field, is paramagnetic.
As I said before, a grounded copper tape outside the core, and a ferromagnetic material (i.e. as a shield wall) will work, I use cheap iron (18 gauge) and works like a charm.
Choke is a nightmare, so I use regulated PSUs.
You can shield it like a trafo, but with care to not to alter air gap.
If you put trafo and choke at the left and PCBs at the right, with a shield in between, magnetic field would be attenuated.
Your preamp looks great as it is, try to improve as it is.
Did you try original PSU with 220uF electrolytics?
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yes i did. Caps that came with the kit was 270uF instead of 220uf. I didn't listen for many days but it was "ok" with a beer in my belly on a saturday night 😀😉
Bad news, mu-metal saturates at about 8 KGauss, for a transformer like of the fotos a guesstimate of 13 KGauss, too much.
I once saw a different value in a book, obviously wrong.
What about these as a replacement?
Deluxe 250V 0 250V 0 4 5 6 3V 6 3V Ct 50VA R Core Power Transformer | eBay
Toroid Transformer T120 120W for Tube Amplifier Amp | eBay
Deluxe 250V 0 250V 0 4 5 6 3V 6 3V Ct 50VA R Core Power Transformer | eBay
Toroid Transformer T120 120W for Tube Amplifier Amp | eBay
As I said before, try first to put your trafo in the right place, you don't need to change it right now. IMHO
You must also put the choke inside the case, and keep fighting with hum, a lot of work before changing the trafo.
BTW, how do you distinguish between 6V3/1.7A and 6V3/0.7A secondaries of your actual trafo?
I don't understand Chinese. 😀
You must also put the choke inside the case, and keep fighting with hum, a lot of work before changing the trafo.
BTW, how do you distinguish between 6V3/1.7A and 6V3/0.7A secondaries of your actual trafo?
I don't understand Chinese. 😀
hehe same here.. I mailed Along1986090 in ebay and he said it was the green one so 😉
When i measured the trafos resistance (230v sec) i got 477ohms, (from 230 to 230, not center tap) i don't remember each 6.3V but think they actually measured similar..
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