Current Question Full wave bridge vs. Full wave

[cbass]

Just going by edcors drawings.THis thing IS bigger than their 250mA transformers but a little smaller than the 300mA .IT has aprox. 2" thick laminations. LIke their 300ma


Edit: IT is aprox the same size as edcors 250mA But this one has thicker laminations.

[cbass]

Worried. The similar Marshall only has capacity for 150mA.

I'm not peavey amps were actually reliable.

[cbass]

I'm gonna make a diseducated guess here. I'm thinking its about a 270 mA PT with Regualr FW rectifier7

And around 170mA with the FWB

[cbass]

Data sheet says max plate current for 250v on plates and screens PP AB 6v6 =79mA

SHould I go ahead and figure 100ma per pair?

If so this PT should run 4-6v6 easily 6 would be pushing the limits

[Phil_S]

You have a Peavey transformer. I'd heard the Peavey is very responsive. I suggest you contact them directly. I expect they will tell you what the PT is wound for and then you won't be guessing. You have nothing to lose and everything to gain.

[tubeswell]

Data sheet says max plate current for 250v on plates and screens PP AB 6v6 =79mA

SHould I go ahead and figure 100ma per pair?

If so this PT should run 4-6v6 easily 6 would be pushing the limits

In Class A a SE 6V6 typically idles at around 36-40mA tube current when biased to 100% (assuming a plate voltage of about 360). Peak DC current through the primary is nominally around 1.2x this amount.

But in PP Class AB1 100mA will easily be enough for 2 x 6V6. (80mA is enough - given that in Class AB1, the tubes are biased at less than 100% - more like 60-85%, and so each tube will be not conducting for part of the cycle.)

[Reeltarded]

Worried. The similar Marshall only has capacity for 150mA.

I'm not peavey amps were actually reliable.

You dick! Ok. That's it. You are never to use a .68u over a 2k7. Don't even think about it.

[cbass]

Data sheet says max plate current for 250v on plates and screens PP AB 6v6 =79mA

SHould I go ahead and figure 100ma per pair?

If so this PT should run 4-6v6 easily 6 would be pushing the limits

In Class A a SE 6V6 typically idles at around 36-40mA tube current when biased to 100% (assuming a plate voltage of about 360). Peak DC current through the primary is nominally around 1.2x this amount.

But in PP Class AB1 100mA will easily be enough for 2 x 6V6. (80mA is enough - given that in Class AB1, the tubes are biased at less than 100% - more like 60-85%, and so each tube will be not conducting for part of the cycle.)

I'm thinking about running the bias up near 100%

[tubeswell]

100mA will still be fine for 2 x 6V6s

[Firestorm]

Wow. This is a lot of mental energy to expend in order to (potentially) save the $ on a new transformer. That one can probably do 4x6v6. If not (if it 's marginal) it won't go all smokey; it will start to drop volts first. That's part of why early Marshalls sound that way.

[Firestorm]

Double post.

[cbass]

It was really more about finding out the diiference between the different rectifiers.
I never had a doubt it would run 4x6v6

\I have issues with words that are in my head gettin to the screen so everything I ask is worded all wrong.

To some people a hundred bucks to spend on transformer is alot of money.
I didn't spend that much on my last build.

[Firestorm]

Hear ya. I was just being snarky.

[cbass]

Snarkopotimus

[tubeswell]

It was really more about finding out the diiference between the different rectifiers.

To understand about the difference between FW bridge and 2-phase FW rectification, its as much about whats happening at the PT secondary as about the way the diodes are configured.

In a SS rectified FW bridge, the diodes are configured to deliver back-to-back +ve current pulses with peaks that are, in peak-to-peak terms, (almost) as much as the peak-to-peak VAC swing across the High Tension (HT) secondary winding. (I say "almost", because SS diodes have a forward voltage drop of about 0.6V)

Whereas with SS rectified 2-phase FW, the diodes are configured to deliver back-to-back +ve current pulses with peaks that are (almost) as much as the peak VAC swing between the HT secondary's centre tap and the respective end of the HT winding that the diode is attached to (which is half of what the peak-to-peak voltage swing is between each end of the HT winding).

To some people a hundred bucks to spend on transformer is alot of money.
I didn't spend that much on my last build.

Whilst its generally prudent to be aware of snake-oil merchants, there is also something to be said for considering the factors that go into pricing of power transformers. Generally an iron-core PT works 'better' if the laminations and the total amount of iron in the core is bigger, because that helps ensure that the magnetising current doesn't saturate in the transformation from primary to secondary, and the PT will generally run cooler and therefore, all other things being equal, last longer. (Heat is the 'enemy' of electronics). More iron in the laminations costs more, and this increases the price somewhat.

'Okay' you might say, 'but surely not THAT much more!' And there you would be using your noggin. Having said that however, its not just the amount of iron that is important in determining quality and longevity, but also the size of the wire in the windings (which affects the bobbin size and also the lamination size), the manner of insulation, the care taken in doing the windings so as to minimise air gaps between the individual bits of wire, which take up space etc, any interleavings in the windings, whether faraday shielding is used between windings etc. These aspects can affect cost and quality. So you need to dig around a bit when looking at new stuff in order to compare apples with apples blah blah blah.