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"Modern" Kondo gear is using SS rectifiers parallel to Tube in power supplies . It seems like tube rectifier is doing precisely nothing there yet people still report their likes /dislikes regarding tube used in rectifier position even though it should be almost negligible without the tube at all. What gives?
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Try listening to this arrangement first before formulating opinions? But I can tell you that theory breaks down when music production is involved. I imagine that the tube rectifier may soften the sound and round it out ever so slightly. There maybe a whole host of things going on such as small amounts of capacitance inherent in the tube etc. I owned a manley labs 300b amplifier years ago that used a hybrid rectifier as well. I was told they thought it sounded better than tube or solid state alone. As far as Kondo goes, I can vouch for the electrolytic capacitors they(Kondo) use in their gear. They are the Unicon brand and they sound stellar. Generic looking but high level stuff.
long discussion on this with the same characters (including myself) taking the same sides.
Some interesting facts from charts though the charge time for a tube rectifier is slightly faster than a solid state unit by about 10% IIRC.
This is the first that a respected designer and manufacturer is using the technique, though.
Thank you for posting and for the photo.
Is the parallel hybrid rectifier useful for low cuurent preamps or just power amps?
I have not used it much for preamps as their current draw is significantly lower. In a few cases I have used it and it works, but I feel the benefits are better realized if you went to diode decoupling first.
I place diodes in series with the dropping B+ resistors with a small caps. The effect is immediate and sonically truly significant
This arrangement will act exactly like SS diodes alone. It's a waste of a good tube.
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Buy Chinese. Bury freedom.
Agreed.
OTOH, the series SS diode tweak can turn shaky current production vacuum rectifiers into solid performers.
Eli D.
But you still get those supposedly nasty on/of rumbling trough the PSU. I have to admit that I've never really compared SS to tube rectification in apple to apple situation and heard for myself all the destructive effects...
The vacuum rectifier totally dominates overall behavior, when rational hybrid schemes are employed. A SS diode in parallel with a vacuum diode is (IMO) NOT rational. For the series SS diode tweak, I recommend the quite quiet UF4007 instead of the very noisy 1N4007, just in case. However, it may not matter.
All PN junction diodes exhibit a reverse recovery spike (switching noise). You start be selecting types, like UFnnnn, that are pretty quiet to begin with. Then, you either snub or block the small amount of noise that is produced. Blocking is what happens in the series SS diode tweak case.
High PIV Schottky diodes are another good option. They are every bit as quiet as vacuum rectifiers.
Eli D.
The audible downside of SS rectification is a risk, but not a certainty. I tend to stick with vacuum rectifiers in low power SETs and the like, but I believe it's less of a consideration (sonically speaking) in higher power PP amps.
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Buy Chinese. Bury freedom.
If they are truly in parallel, there are no technical advantages. The solid state diode is an incredibly low impedance device compared to any tube rectifier, while the tube rectifier is sitting there doing almost nothing.
There will be audible changes with any without the tube, but it may be as simple as power transformer loading having as much influence as anything else.
It appears that Kondo uses this rectification scheme in all new products....
Been doing that for decades now: Tube still adds more midrange and dynamics. Transistor adds bassOh yeah, the relative differences between rectifier tubes is still distinctly audible, but now I can pretty much run any rectifier tube I desire.
The most fun is to grab a pot holder and invite some tube loving friends over. with the amp playing; walk up to it and yank the tube rectifier out. Be sure to have a towel to wipe the jaws from the ground....L)L!!!!
Edits: 04/02/15
You pull the rectifier tube, you just dropped a 10-15 watt load on the PT from the rectifier tube filament.Yes, it sounds different because no doubt the B+ just rose!
As for commercial implementations, a brilliant marketing ploy. The non technical audiophile gets their beloved tube rectifier and it never ages or dies. Great for warranty and product reputation.
Edits: 04/07/15 04/07/15
Yo Gusser. I was reading Basic Electronics by Van Valkenburg et al, 1955, and it stated that when mercury was added to a rectifier tube, then it becomes a rectifier and a voltage regulator. So there's a scientific answer for ya on that one.
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Big speakers and little amps blew my mind!
Hi Stu, is the forward voltage drop thru the tube rectifier still fixed by the type of rectifier? I have been using 5y3, 5r4, 5u4, and 5ar4 to vary the B+ in my amp. Will adding the SS diodes negate the voltage drop thru the rectifier tube? And what is the arrangement of the diodes in the Kondo amp if I wish to retrofit them into my amps? cheers, Dak
That's not for you, DAK ;)
You seem to like tubes... and this is one for people who like to show off tubes and play practical jokes with their friends.
This is a cheap and dirty trick. The tube rectifier is totally bypassed by the diodes. Good for marketing purposes (has a tube rectifier in sight) and for servicing purposes (if the rectifier tube dies you are not going to notice it, and since it just sits there doing nothing you can use any tube rectifier that fits the socket).
This is the total opposite to hybrid bridge, or series connection of tube rectifiers and SS diodes - both combinations having a technical purpose and possibly some advantage.
******
http://rh-amps.blogspot.com/
there are definite benefits of solid state and of tubes. Why not take advantage of both.
You need not believe me, but if Kondo uses it there must be something, wouldn't you think.
Any way I have a more than adequate stock of NOS 5AR4's, the rest of you can go on struggling with the marginal Russian and Chinese stock. Ty running an older QS with 320 uF after the rectifier: GE's could take that abuse, no modern tube can
Yeah, you gotta treat the circuit as if it is solid state. BTW, I've tried all the FR types and still the tube takes precedent sonically. Its just I can run a bigger cap bank to pump up bass and dynamics.
One f the guys on the Joelist came over once and His eyes nearly popped out when I went up and yanked my rectifier tube right out of the playing amp> Made no difference in the music except that it didn't sound wgite as good
The tube drop would be negligible and watch for capacitor ratings . You would have to put tube rectifier in series after SS to get the slow start and a drop I think.
Yeah no slow start for tubes, but then the ss diode takes most of the strain anyway. You can hear the rectifier tube warming up.Strange how I seem to be the only guy to have actually tried this arrangement. For a DIYer, it takes only a few minutes....
Edits: 04/10/15 04/10/15
"Yeah, you gotta treat the circuit as if it is solid state."
This circuit IS solid state. The vacuum tube sits there beautifying the amp!
If you can hear any difference when changing rectifier tubes, that's placebo effect: you want to hear it.
******
http://rh-amps.blogspot.com/
I demoed the effect to a member of the Joelist, who was blown away when I yanked the rectifier out of a playing amp ( monoblock).
After his initial shock, he could hear differences between channels and favored the one with the tube. Now I can her differences between various rectifier tubes, both in manufacturer and types. The same sonic difference is translated into this hybrid configuration.
You can use "common" sense to say that there can be no difference. Practicality suggests otherwise. If you haven't tried it, then you really should not comment.
"You can use "common" sense to say that there can be no difference. Practicality suggests otherwise. If you haven't tried it, then you really should not comment."
I have not tried Russian roulette either, or jumping from the roof of a building for that matter, but I still can comment how those activities are risky and most probably lethal.
The difference in resistance between the SS diode and the tube rectifier diode is so huge that the latter introduces no relevant change in the parallel resistance.
Being commercially involved in this scene does not authorize you to dictate who should or shouldn't comment on issues that are not common sense but hard physics.
I guess adrenaline addicts who play Russian roulette and perform similar stunts would similarly dismiss amy attempt to explain the dangers of their pastime. Just add the gun dealer who supplies them with weapons and you'll get exactly what I mean.
******
http://rh-amps.blogspot.com/
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