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Post by runninwiththerevil (Matthew) on Jan 10, 2021 12:41:19 GMT -7
It isn't too often that a Dr Z or a Matchless comes up on the local Craigslist, so I'm always interested when they do. I was zooming in on the tube chart for a SC30 post. It has two rectifier tubes. I've read Pittman's book and have a decent understanding of how an amp works. I don't recall that he talks about designs with two rectifier tubes (I borrowed the book so I can't consult).
Curious for those in the know, what does a circuit do with two that it can't do for one? How common is this, I don't think I've ever even seen a spec list with two rectifiers listed. I ask this assuming that two rectifiers are still doing the same type of work of converting the power, but maybe that isn't a correct assumption. Some body talk me to school. Are there any of Dr's designs with two?
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Post by Paul (TRANE) on Jan 10, 2021 13:11:50 GMT -7
"The rectifier circuit gives you the flexibility of using one 5AR4 for a quick attack or you can use two 5V4’s for a smooth, round response". That is from Matchless site. The 5V4 gives less voltage, which will translate to more sag and the rounder response. The 5AR4 gives more voltage makes the amp more percussive and immediate. I prefer the 5AR4 so far, personally.
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Post by Jaguarguy (Mike) on Jan 10, 2021 16:21:34 GMT -7
The EMS is switchable between a tube rectifier (5U4GB) and a solid state rectifier.
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Post by sharkboy on Jan 10, 2021 18:03:16 GMT -7
For the Matchless double rectifier: It is important when using 2 5v4s that they are matched, as current throughput may be dramatically different- which could harm the one with lower resistance, and could harm other components. The quick answer for why this makes a difference is that there is higher resistance through the 5v4s which results in a little more sponginess in feel and slightly lower voltage to all the tubes.
That said an original Matchless DC30 or HC30 with a single 5AR4 is one of the greatest sounding amps that the good Doc didn’t make. I have a clone, but never felt the need to even try it with a 5v4 pair. My clone was my go-to amp for years before I bought my ZWreck.
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Post by zpilot on Jan 11, 2021 3:40:44 GMT -7
Somewhere around 2006 I remember Fender built a point-to-point wired low-power Tweed Twin that had sockets for two rectifiers. I believe it was a re-issue. It came with a pair of 5U4G's. I had an opportunity to play through one. If I remember correctly you could pull one of the rectifiers in order to get more sag. With both installed it acted more like it had a single 5AR4. I thought it was kind of neat. Running two 5U4G tubes really puts a load on the power transformer though since that tube has a high current draw for the heaters.
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Post by Paul (TRANE) on Jan 11, 2021 10:07:30 GMT -7
Somewhere around 2006 I remember Fender built a point-to-point wired low-power Tweed Twin that had sockets for two rectifiers. I believe it was a re-issue. It came with a pair of 5U4G's. I had an opportunity to play through one. If I remember correctly you could pull one of the rectifiers in order to get more sag. With both installed it acted more like it had a single 5AR4. I thought it was kind of neat. Running two 5U4G tubes really puts a load on the power transformer though since that tube has a high current draw for the heaters. Yeah. I owned one of those for a bit. Nice amp good grind when cranked up. Sold it a while ago.
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Post by zpilot on Jan 12, 2021 0:28:21 GMT -7
Somewhere around 2006 I remember Fender built a point-to-point wired low-power Tweed Twin that had sockets for two rectifiers. I believe it was a re-issue. It came with a pair of 5U4G's. I had an opportunity to play through one. If I remember correctly you could pull one of the rectifiers in order to get more sag. With both installed it acted more like it had a single 5AR4. I thought it was kind of neat. Running two 5U4G tubes really puts a load on the power transformer though since that tube has a high current draw for the heaters. Yeah. I owned one of those for a bit. Nice amp good grind when cranked up. Sold it a while ago. Care to elaborate on your experience with it?
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Post by Paul (TRANE) on Jan 12, 2021 20:37:42 GMT -7
Let me see. I really liked the normal channel on that Tweed Twin. The high treble was too piercing. At least for my ears. It sounded good but had to be cranked up over half way to get the sound I go for. I always used my Les Paul with it. Overall it was a very nice amp. Well made and easy to bias and such. The tone was reminiscent of my Germino Classic 45. It made me think I need to try a Victoria Double Deluxe some day. I sold it to a local player. Guy could play and had been looking for that amp for a bit.
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