My first preamp with tubes

[Airhead]

Yeah, I buy most of my components from Uraltone.

 

[Max Martin]

I got my "inMADout" transformer today. Weights in on 2,7kg...(5,95 ib) Looks well made (but i also said that about previous..) Made in Italy.

One thing that strikes me is that only one sidecover have plasticwashers and other side doesn't? I heard/read something that you can saturate the transformer if cover have contact with the screws/bolts. Maybe somebody understand better what they thought/how it's working?

Anyone have a thought about the washers?

 

[Magz]

Anyone have a thought about the washers?

Most of the transformers I've used have at least one bolt that makes electrical contact with the covers/core, and transformers that have an electrostatic screen often have it grounded at one of those bolts, rather than having a separate wire. In all cases, I make sure that the exposed transformer parts are securely grounded to the chassis just for safety's sake.

 

[Max Martin]

Just for fun, Italy 155VA vs China 30VA.

Project is going slow, i ran out of solder tin... I've been building a new cinema and 5 new speakers have taking up a lot of time. Next week maybe.

 

[Max Martin]

I'm trying to simulate more with duncan but all the time i get this;

Is it bad/dangerous to go over this limit? I remeber my old psu exceded this value by 0,26, just little more. I really don't know what they mean with this

 

[Shoog]

I try to avoid that, but its generally not as bad as it looks as the heater warm up slows everything down to the point where it doesn't really happen. However i would mess about with the value of R1 until it doesn't happen.

Shoog

 

[Max Martin]

I built little today (i'm surprised)

I wonder where choke could go for noiseless operation?

How else does you pro's here think about it? I moved back pt little to have more space for rectifier in coke bottle later on.

 

[Max Martin]

Put 2 fuseholders for sec (2x300v) before rectifier.

 

[Max Martin]

.

 

[Max Martin]

..

 

[Shoog]

Looking good, have you listened to it since ? Are all issues resolved ?

Shoog

 

[Max Martin]

No, it's only as you see, wiring to do and mount choke but i'm not sure would be a good place. Keep it away from signaltubes as much as possible. Thinking sidewall next to pt?! Hmmm...

 

[Shoog]

No, it's only as you see, wiring to do and mount choke but i'm not sure would be a good place. Keep it away from signaltubes as much as possible. Thinking sidewall next to pt?! Hmmm...

Underneath the Power transformer if it will fit.

Shoog

 

[cjkpkg]

Looking good Max!

 

[Max Martin]

Thx guys. I did my best

I will here show 2 possible (only ways) to mount the choke.

Nr 1: sidewall, vertical. Less radiation?

 

[Max Martin]

Nr2: like shoog suggested. Very tight though. Spacing is to small to mount it other ways (70mm, almost 3") pt is bigger than that...

 

[Max Martin]

Only thing i have not checked for error is this filter, can it be something wrong with it? How can i check it ? I have r, c, h meter.

 

[Shoog]

Sidewall looks best.
It's highly unlikely that filter has gone down and if it had it would have taken out the line fuse without effecting anything downstream from it.

Shoog

 

[fdegrove]

Hi,

Only thing i have not checked for error is this filter, can it be something wrong with it? How can i check it ? I have r, c, h meter.

Don't bother. Even if it didn't work it couldn't do any harm.

Ciao,

 

[Max Martin]

ok thanks. Just out of curiosity i measured and values mentioned on the sticker seems to be what they say so...

Ok shoog, on sidewall it is