1959 Transformers

[Master of Sparks]

Metro C1998V OT !!!! Tone for ages !

[Master of Sparks]

So like transformers what you need is something that electronically is crap but the whole bad specs color the sound and make it the great sound of theese amps.
So I think I'd go for Stad Up Metroamp ones...
What's the main difference between self lead or normal C1998?
I have only to find a 4 holes Choke.

You want an OT that gets rid of all the undesired frequencies and only lets the right ones pass, especially when the amp is turned to 10 and alot of poweramp grind is going on !!!

[cos000]

Thanks for the replies.
I think I'll go for Metroamp Transformers. Let check for relatives in the US...
For the choke:
I have a chassis that has 4 holes for the choke and the one that is compatible for it is a 5H, 120mA, 120Ohm. Is it ok?

EDIT: Does someone have a picture of the C1998V so I can see how a self lead transformer looks like? Because the wiki doesn't work...

[neikeel]

Here is the Metro PT:

[cos000]

Thanks so much!
And what's about the choke?

[neikeel]

Thanks so much!
And what's about the choke?

On JTMs I like the Metro 354-114 best (not sure if George is doing those still, a 3H choke) the Dagnall C1999 is pretty much the same and that is what I use in 12 series types, although the Mercury 5H works just as well.

[cos000]

Ok.
So Metroamp Transformers would be the best choice...?

[stef]

[youtube]http://www.youtube.com/watch?v=Fcabc00kZ7w[/youtube]

[neikeel]

Ok.
So Metroamp Transformers would be the best choice...?

I very much doubt that you will go wrong with any of the '3 Ms' transformer sets, and maybe the classic tone, down to availability and maybe price.

The above clip posted by Stef should help.

[cos000]

Ordered everything.
Now let cross the fingers and wait for relatives to come...

[cos000]

Finally, after a faulty power transformer that completely disconnected needed more than 100W and blew me all the fuses that I had(I've got another one and it works).
I have few questions: By powering it up completely disconnected it needs 460mA on 235VAC... It seems so much for me...
Is it normal?
Second: sometimes the main 2A slow blow fuse blows when powering on the amp... what could it be? The plug on the wall hasn't ground. I think, because it happens sometimes, that it depends from when I switch the amp on: If I switch on when the Sine voltage of the wall is on the max point (both positive or negative) or when it's near to 0. In the first case I'd have a inrush current too high...
Third: After warming up tubes, when I power on the amp from the speaker come out a sort of crackling, popping that goes away after a minute... Also here what can I try?
Fourth: When I firstly had to set bias, with no power tubes installed it went from -39VDC to about -50VDC. Are theese value possible? Then I put on the EL34s, plug a cab, warm up and switch on: The bias voltage drop on the 1Ohm resistors was from 6 to 8mV. SO I had to turn so much up the bias pot... Also here is right? The power tubes haven't redplating issues so I think it's ok (I set bias on 33mV on the tube with highest bias voltage).
Fifth: Is it normal that the power transformer becomes pretty hot?
Sixth: The amp sounds great with a LAR/MAR PPIMV!

I'll put on the thread a voltage chart to be sure of the voltages...

[neikeel]

300mA is more like what I would expect and maybe why yours is getting hot, something is drawing too much juice.

I'm also confused when you say completely disconnected - should draw no appreciable current. Heaters will be a few amps and the bias 50mA, can you explain how you tested?

Whose PT did you use?

[cos000]

300mA is more like what I would expect and maybe why yours is getting hot, something is drawing too much juice.

I'm also confused when you say completely disconnected - should draw no appreciable current. Heaters will be a few amps and the bias 50mA, can you explain how you tested?

Whose PT did you use?

Thanks for the reply.
Completely disconnected means the transformer out of the amp with the leads not connected. Only the primary 240V on the 230V from the wall.
I tested it with a multimeter connected in serie to the primary winding on 20A scale.
I also used a cheap power meter and it said 16W idle always with all taps disconnected.

The PT is a 1203-80-MS.

[cos000]

Can someone make a test and say how much current is the amp draining with all the knobs to 0?

[cos000]

I thought a little bit on this thing and made few tests with and without tubes. With tubes it starts from 100W and it reaches quickly 67W but the multimeter gives a current of 0,69A... So I tested a lamp of 70W and the two measures were about the same... So what I thought is that the multimeter measures the effective value of current: that means that when I calculate power I include also the reactive power and not only the active one...
The value with the transformer disconnected (test that I made when I bought it) it's the same now that it's connected but without any tube installed and the result are 16W with power meter and 0,45A with multimeter...
I'm gonna buy a bettere multimeter this afternoon...