Marshall recto set up

[Stevem]

Other than the 100 watt amps PTs not having a secondary center tap what would be the reason that marshall uses a bridge recto in the 100 watt amp , but not in the 50 waters?

[strelok]

Which 50 and 100 watt models are you referring to? And from what era? All the 1987's I've ever seen had bridge recto's in them. Some where diodes mounted on the board others had an actual bridge unit mounted to the chassis or occasionally on the board. Marshall kinda used whatever they could get back in the early days. If they did use a two diode full wave setup my guess would be because that's what transformers they had available at the time. However I haven't seen it and a quick glance at google images didn't reveal any either.

[RWood]

The only 2 real 1987s I've had the good fortune to see inside of both had 4 diode (2 in series on each side) full wave, not bridge...but I can't attest that they were not modded. My friend who has been a tech for 30 years says he has seen a few FWBs on 50 watters, but most often FWs.

[sluckey]

None of the 1987 schematics show a bridge. In fact, none of the old classic 50 waters show a bridge.

[strelok]

My bad I was looking at the four diodes in gut shots and assumed the secondaries where connected in the center making them a bridge. Guess that what happens when I post after midnight There are a few pics floating around of 1987's with self contained bridge recto's though and the Metro clones in the early days had the same.

To answer OP's question I don't think it really makes much of a difference. Most likely it was probably the parts they had available at the time, just a guess though.

[Stevem]

This on the silver J reissues, the preamp / power supply board is made to be wired up different between the 50 and 100 waters.
I guess all the 100 watt PTs for these are made without the secondary center tap.

[sluckey]

There are a few pics floating around of 1987's with self contained bridge recto's though and the Metro clones in the early days had the same.

I believe Metro still uses a bridge block. But the negative side is not connected, so only two of the diodes are being utilized. The bridge is being used as a conventional two diode full wave rectifier and the PT has a center tap on the HT winding.

[Roe]

Other than the 100 watt amps PTs not having a secondary center tap what would be the reason that marshall uses a bridge recto in the 100 watt amp , but not in the 50 waters?

the early 100w amps did use a center tap like the 50w. but the 100w underwent some heavy changes in the power supply, where the bridge recto ended up representing the easiest and cheapest solution probably. The 100w amps used higher voltage than the 50w amps and the 100w CT PT, the 1204-43, was overly big, costy and costy. the C1998s were more practical

[strelok]

There are a few pics floating around of 1987's with self contained bridge recto's though and the Metro clones in the early days had the same.

I believe Metro still uses a bridge block. But the negative side is not connected, so only two of the diodes are being utilized. The bridge is being used as a conventional two diode full wave rectifier and the PT has a center tap on the HT winding.

Now I feel extra silly.