Power transformer fails

[Roe]

Tube Town lists the same Hammond 290EEX as I linked at Mouser EU above at nearly the same price. Don't know about shipping cost.

yes, and they offer some other transformers too and the shipping and delivery times are not bad at all.

[Oddvar R]

Tube Town lists the same Hammond 290EEX as I linked at Mouser EU above at nearly the same price. Don't know about shipping cost.

yes, and they offer some other transformers too and the shipping and delivery times are not bad at all.

At mouser you get free shipping on the Hammond transformer.

[Roe]

Tube Town lists the same Hammond 290EEX as I linked at Mouser EU above at nearly the same price. Don't know about shipping cost.

yes, and they offer some other transformers too and the shipping and delivery times are not bad at all.

At mouser you get free shipping on the Hammond transformer.

that's even better! (if you want the hammond and not some of the other PTs offered by TT)

[Oddvar R]

yes, and they offer some other transformers too and the shipping and delivery times are not bad at all.

At mouser you get free shipping on the Hammond transformer.

that's even better! (if you want the hammond and not some of the other PTs offered by TT)

I have tried the TT ones,bought a lot from them. I returned the Dumble ones I bought, with a lot of hazzles I must say. They didn't sound as goog as the weber did. That's why I have bought 3 of the Webers, they sound very good to my ears.

[bepone]

I have tried the TT ones,bought a lot from them. I returned the Dumble ones I bought, with a lot of hazzles I must say. They didn't sound as goog as the weber did. That's why I have bought 3 of the Webers, they sound very good to my ears.

interesting that someone returns power transformers....never happen to me, but can be a new light on the system. are you in europe ?

[Oddvar R]

I have tried the TT ones,bought a lot from them. I returned the Dumble ones I bought, with a lot of hazzles I must say. They didn't sound as goog as the weber did. That's why I have bought 3 of the Webers, they sound very good to my ears.

interesting that someone returns power transformers....never happen to me, but can be a new light on the system. are you in europe ?

I am in Norway. I have always thought that power transformers soun sort of neutral, but the TT ones were very hard in it's sound compared to the Weber. My 50w ODS sounds fantastic with the Weber, so the TT' Dumble 50w PT's was a bit of a let down. (So I returned them to Tube Town, they say you can return goods, they have a page for it. But they were very unhelpful, almost agressive in their mailings. It ended with me loosing more than half the money, to cut a long story short.)

[martin manning]

I have always thought that power transformers soun sort of neutral, but the TT ones were very hard in it's sound compared to the Weber.

Did you notice any significant difference in the B+ voltage between the two, particularly preamp tube plate voltages?

[Oddvar R]

I have always thought that power transformers soun sort of neutral, but the TT ones were very hard in it's sound compared to the Weber.

Did you notice any significant difference in the B+ voltage between the two, particularly preamp tube plate voltages?

I should have, but I didn't. I was so sutprised that the sound was so different, that i couldm't live with it.

[bepone]

I am in Norway. I have always thought that power transformers soun sort of neutral, but the TT ones were very hard in it's sound compared to the Weber. My 50w ODS sounds fantastic with the Weber, so the TT' Dumble 50w PT's was a bit of a let down. (So I returned them to Tube Town, they say you can return goods, they have a page for it. But they were very unhelpful, almost agressive in their mailings. It ended with me loosing more than half the money, to cut a long story short.)

ok but in norway there is 230V line.. how did you fit 120v weber to 230V - some stepdown trafo?
i'm building myown trafos or using only local suppliers for winding power transformers and didnt have this kind of problems before... harsh sounding because of power trafo?

[bepone]

also, any decent company can build perfect power transformer.
\
pls send me your broken trafo maybe i can help to rewind, but specially im interested how the trafo failed.

[Oddvar R]

I am in Norway. I have always thought that power transformers soun sort of neutral, but the TT ones were very hard in it's sound compared to the Weber. My 50w ODS sounds fantastic with the Weber, so the TT' Dumble 50w PT's was a bit of a let down. (So I returned them to Tube Town, they say you can return goods, they have a page for it. But they were very unhelpful, almost agressive in their mailings. It ended with me loosing more than half the money, to cut a long story short.)

ok but in norway there is 230V line.. how did you fit 120v weber to 230V - some stepdown trafo?
i'm building myown trafos or using only local suppliers for winding power transformers and didnt have this kind of problems before... harsh sounding because of power trafo?

This transformer is built for the 240v market.

[Roe]

At mouser you get free shipping on the Hammond transformer.

that's even better! (if you want the hammond and not some of the other PTs offered by TT)

I have tried the TT ones,bought a lot from them. I returned the Dumble ones I bought, with a lot of hazzles I must say. They didn't sound as goog as the weber did. That's why I have bought 3 of the Webers, they sound very good to my ears.

do you mean output transformers, or power transformers? Specifically, which transformer did not sound good to you?

[JD0x0]

A quick and dirty estimate of the current required: 50W/330V = 0.152A, At 50% efficiency, that's 300 mA.
It won't be running at 50W 100% of the time, so 66% efficiency might be more realistic, for 230 mA.
I would say the Weber unit is right on the edge. A better bet is this 270 mA Hammond Bassman replacement: https://eu.mouser.com/ProductDetail/Ham ... 3P7Q%3D%3D

Hmm, my quick and dirty calculations say that 200mA would be just fine. 60mA plate current per tube @420VDC would give 100% dissipation for an EL34 (I know we use 70% max for class A/B fixed bias, but we do want some leeway, so I will use 100% dissipation - technically 100.8%) add in 5% screen grid current. So figure ~132mA for the power tubes. Then we can guestimate 6mA (design max) for each preamp tube for an additional 18mA of current. So, we're at ~150mA. Of course, this doesn't account for the amp being in a failure mode, but under normal operation 200mA should be fine, or am I missing something?

Edit: 6L6's would take a bit more current, About 160mA for the pair with screen current. So figure, ~178mA total for 6L6's, which I guess you could consider somewhat borderline, but these figures are also a 'worst case' for a properly functioning amp that's biased way hot.

[Roe]

my experience with a weber twin PT was that it got hot and sagged a lot with 230v/50hz. the next transformer sagged way less, something that gave more power and punch. but you do loose some breakup, compression and mids. Perhaps that was what Oddvar was after here?

[bepone]

then those transformers are failing on basics...