I understand input and output tubes, but I can’t work out why rolling the rectifier tube is worthwhile.
Any help out there?
@RonP a rectifier tube is functionally similar to two diodes connected as a full-wave rectifier on the center-tapped secondary of your power transformer. Different rectifier tubes have “harder” and “softer” regulation or voltage drop which allow the HV bus in your amplifier, pre-amplifier, etc. to sag less or more. This (in my experience with a pre) results in a somewhat tighter or looser (mellow?) sound. So, whether you choose NOS or new there are differences in SQ with the various rectifier tube types. Some of the large “Coke Bottle” shapes tend to be “mellower” and some of the smaller cylindrical “military” tubes tend to be tighter / brighter. There are even solid-state rectifier tube replacements that have two diodes for perhaps the “tightest” sound of all.
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And, interestingly, solid-state tube replacements can sound different as well.
Maybe just semantics but I thought you needed four diodes for it to be considered a “bridge” rectifier?
See correction above. I was in a hurry. “…two diodes connected as a full-wave rectifier on the center-tapped secondary of your power transformer.”
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Possibly no help, certainly no technical explanations, but I’ve been doing this for a few decades and it makes fascinating differences, expecially when you have such a simple circuit and transparent a playback machine as the Decware amps you and I have. I have about thee boxes full of rectifiers. . . .
Be aware that the solid state rectifiers may not have the “soft start” feature that tube rectifiers have. The power supply will get full voltage when turned on. With a tube the voltage rises as the the tube warms up.
They also may not have the resistance that a tube rectifier has which would raise the operating voltages within the amp a bit. This could potentially shorten the life of the tubes. I would check your wall voltage with a good meter to see what you’re getting. If it’s higher than 122VAC then I would stick with tube rectifiers.
One benefit that a solid state rectifier typically provides is a little tighter bass and better dynamics.
There’s a simple mod for tube rectifier sockets that can protect your rectifier tube, maintain the soft start feature and voltage drop, yet provide the more stable rectification of solid state devices. But it involves a little surgery in your amp. Basically adding a 1n4007 diode to each leg of the high voltage secondary at the input of the rectifier socket. So the high voltage would be rectified by the diodes first and then be in series with the tube rectifier.
No surprise, Lon! Have you settled on a favorite?
PS—Man, am I loving this little squirt of an amp!!
PPS—It makes no sense how well this little thing produces realistic sounding bass.
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In my case (my SE84UFO3 Monoblocks with the 25th Anniversary Mods) it’s a matter of which rectifier is best with the other tubes (output, voltage regulator for the outputs, input, voltage regulator for the inputs). Change one and a different rectifier may work best. I generally leave the output and the voltage regulators the same (my favorites: Steve’s output tubes, and 0B3 and 0A2) and will play with inputs and rectifiers. At the moment I have a pair of Cunningham Type 80 Globe rectifier with adaptors in with a pair 6SN7 tall boy RCA input tubes with adaptors.
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I’m just throwing out my experience with Rectifiers on my WOO WA5-LE Amp. It uses 300B family tubes for power, 6SN7 family tubes for Drivers and 5U4G tubes for Rectification. I started with 274B tubes and then I used a pair of EML 5U4G’s and they were the last tubes I upgraded. They make a contribution that’s certainly noticeable, but not component level. I moved to 596 tubes with adapters as a replacement for the excellent EML 5U4G’s. WOO sells these as an option. They also bought up most of the available stock of 596’s and pushed up the prices as they were an excellent sounding tube. I paid $100 US per tube. They can be as much as $350 US each now. Tube rolling can be fun and gratifying. Like all things audiophile it’s only limited by time and money.
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Hey fellow Hi-Fi family, from my experience with tube guitar amps with tube rectification, I have/had amps with 5Y3’s, 5U4GB’s & 5AR4/GZ34 type tubes. 5Y3’s are usually found in lower wattage amps & most likely don’t apply to hi-fi units. 5U4GB & 5AR4/GZ34 types are very popular with guitar & hi-fi amps. Watch out for what your amp calls for, different rectifier tubes will fit & function, to a degree. However the voltage demands can be quite different & there will be trouble with some substitutions.
Generally, the 5U4GB types are “looser & warmer” sounding with less headroom. The 5AR4/GZ34 types are “tighter & cleaner” sounding with more headroom. Whichever type your amp calls for, and keep in mind this has been my experience (40 odd years) stick with NOS, USA or UK made tubes if you can find/afford them.
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I’ve played with tube rectifier rolling in preamps. Dan Wright over at Modwright tends to favor tube rectification combined with chokes in his designs and that’s where my experience derives from. My observation is rectifier rolling is quite a bit more subtle than rolling small signal tubes which are the actual active gain devices in an all tube design. The difference between tube and solid state rectification isn’t subtle at all, especially the soft recovery characteristic others have mentioned which is inherent to that device type itself. Dollar for dollar when I’ve had an all tube pre in-house (e.g. the original Modwright SWL 9.0) I’ve favored spending my finite bucks on the signal tubes.
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I use United 596 rectifiers in my Woo WA5-LE with adapters in place of 5U4G tubes. They used to be cheap and I bought some NOS backups. The price has skyrocketed on them.
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