Hey WW!

[MikE]

This is what you were looking for. Ante' up?

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=1750785591

MikE

[Rob]

"Tube tests 48 out of 40 minimum". Well that means the tube is almost at the end of its useful life. It is presently at $80 US. I shakes me head. When are toob people gonna learn that the rectifier tube DOES NOT AMPLIFY and therefore DOES NOT INFLUENCE THE SOUND.....unless.....THERE IS SOMETHING W R O N G WITH THE POWER SUPPLY, EITHER THROUGH COMPONENT FAULT, OR BY INADEQUATE DESIGN!!!!!!?

I fall out of my chair with laughter every time I see a WE-274B go for $500.00 US used or $750.00+ NOS. Ha, Ha, Ha. A $5, 5U4 does the same job folks!

Rob

[MikE]

Them there's fight'in words partner!

Honestly I'm familiar with the so-called "importance" of rolling rectifiers and the point you address is not new, least to me. That if the power supply is very well designed, the effects of rolling rectifiers are not very dramatic, probably limited to the difference in voltage drop from brand to brand and the tolerances (resulting in differing noise). And that the design and components chosen for a power supply have a far more dramatic effect than a trick rectifier - agreed.

That said in my limited experience with my Moth s45 45 SET these last four months I must admit that various rectifiers HAVE had a significant effect on the amp and the overall system sound. Does this mean that the design, parts or build execution is lacking in my amp as you, and others suggest? Or does it have something to do with the importance I place on discrete variances? I don't know. Of the dozen or so enthusiasts I know that have owned Moth amps everyone has been very pleased with the design, parts and build quality and more important the amp's performance and musical satisfaction rendered. This in direct comparision vs the (other) most respected SET manufacturers out there; Jeff Korneff, Audio Note, Wavelenght, Wright, Cary, Welborne. Most have had success, as I have, with rolling various tubes; output, input or rectifier. I'm not the only one to report of the benefits that suggest a negative aspect with the amp's design.

While my amp is NOT stock, having implimented a few select upgrades with even better parts (with designer's approval) even the stock parts are considered of very high quality. The custom Electra-Print OPT that Jack built for the Moth s45 is one of the best available. While I do not profess to be knowledgable, like yourself in amp design or even tube effect, I can only report what I hear as honestly as possible if my words are to have any meaning. And leave that for others to interpret the relative worth or usefulness. CONTEXT: I have 22 rectifiers of 11 various types; 5ar4, 5r4, 5y3, 5v4, 5u4 with many variations within those types. My amp can use either a 2a3 or 45 output tube (with a minor bias adjustment) one of the reasons for the diverse grouping. My OPT has 3 amp windings that can run the 5u4 and 5v4 without a problem. The rectifier differences I speak of are as greater than the variances between the various 2a3 or 45 output tubes but NOT as greater as the difference between the 2a3 vs 45 tube type. That is IMO a huge difference or improvement in performance - the 45 (either ST or earlier globe) walks all over the 2a3 examples I have (Sovtek or RCA bi-plate).

Thanks for the "warning" about rectifiers but good or bad, I'm a big proponent least with this one amp, and in the context of My system. YMMV and all that yuk, yuk...

MikE

[MikE]

Here's one of the front-end.

[MikE]

And one of the top-side

[Rob]

Mike, All,

I'm not trying to start a fight. I'm not picking on anyone's tube amplifiers either. I'm just stating an engineering fact. The truth is DC, the form of current that the amplifier needs to operate with should be non wavering and available at sufficient current levels to drive the speakers to adquate power levels according to the designer's wishes. IMO, if you can hear a difference in the sound by rolling rectifier tubes then IMO, either some of the tubes you are trying are not up to the demand of the amp, or there is a shortcoming in the power supply design.

Having said that I'll add this. It is possible that a designer will purposefully design a power supply in an amp so that the rectifier tube operates too close to threshold and that one then has to hand select from a batch of rectifier tubes so that at least one meets the threshold and delivers the goods. This could be done on purpose to help the sale of a specific brand of specially over-priced rectifier tube. In engineering terms this is called a C O N S P I R A C Y . ;) It may also be done as a cost cutting compromise Either scenario is not good design practice IMO.

If someone hears a difference in the sound between rectifier tubes it is because the rectifier tube is not doing its job properly and is altering the dynamic transfer characteristic of the amplifier. In engineering this is called D I S T O R T I O N.

I say again. the rectifier tube does not exist in the signal path. It only has one simple job to do, albeit that job is of almighty importance. It is supposed to make DC from AC. Note that pure DC applied continuously to a loudspeaker makes absolutely no sound (within loudspeaker rating).

The reason I laugh is because there is soooo much marketing hype in audio that trends develop and I've observed from ebay that a particular maker of admittedly very, very good tubes who's initials only I will use here to protect the anonimity of the maker, let's call it W.E. ;) , that any tubes so marked are reveered as the 'nectar of the gods' and even if the particular type in question is grossly mischosen for the job, it will be placed in a circuit at huge artificially, market driven cost and then whatever the sound, the unwitting buyer has no choice but to convince himself or herself that it sounds great, or possibly feel so cheated that suicide might be the result. I mean after spending $745.00 US, (thats's over $1,100.00 CDN), M O R E than necessary for a rectifier tube for your amp because you fell into the marketing trap, are you honestly gonna believe that the sound that comes from your amp now is anything less than perfect?

So much of this is all marketing driven nonsense to me and it makes me laugh that's all. This is of course my own opinion and I'm entitled to observe and form my own opinion. I've been laughing so hard at the phenomenon for long enough now that my ribs hurt and I thought others would appreciate being let in on the joke. IMO a great many of you out there are being cheated by partial truths and cleverly crafted, deliberately misleading advertising. It is my hope that through this forum at least some of you will learn how to recognise smoke and mirrors when you should easily see them being used.

That is a really nice amp Mike. I would love to hear it on my newly constructed full range horns. Perhaps it can be made even better with power supply modifications. Have you ever scoped the B+ rail to the output transformers during operation while you are 'rolling' rectifiers? Such diagnosis should show why different rectifiers sound different, and point to engineering changes that could eliminate this 'floating point'. Make sure that you do not overvoltage the rating of the scope probe or the scope when you do this. Extra series resistance may need to be added in series with the probe. Absolute voltage readings are not of any interest in this test. the dynamic waveform or 'modulation' is what you are looking for. An ideal circuit won't have any. Don't be disappointed if you see some however, an ideal amp doesn't exist.

Respectfully submitted.

Rob

[MikE]

Hopefully you noted the half-kidding tone of my post. Like you say, "you're entitled to an opinion", and I respect YOUR opinion. I was just sharing with the readership a constrasting opinion. While acknowledging the extent of my understanding of amplifier topology I find it interesting that ALOT of other experienced tube enthusiasts have found similiar observations that I have. Though I admit I'm not certain if they explain the reason for such, as many have noted with the "rectifier non-issue". It is puzzling.

No, I have not hooked up a scope to the OPT. Perhaps I'll give Craig a call at Moth Audio and bounce the "rectifier effect" off him. As far as the "conspiaracy theory". Speaking only for (or about) Moth Audio, my amp comes stock with either a current production 5ar4 Sovtek or a NOS Chatham 5r4 (users choice), NOS 6an4's and no output tubes. You can purchase discounted Sovtek 2a3's seperately. While I have talked with Craig numerous times about compatibility of various rectifiers (Bendix 6106 5y3, 5v4,5u4) not once has he even offered a recommendation for a specific brand, or even the preference of current production vs vintage. In this one respect he has been rather coy. So no conspiracy, least with Moth Audio. I appreciate you sharing your knowledge on this subject.

One of these days I'll explore horn "loonie land" as most people think I'll be happier with one (based on my replay preference) but till then I'm happy as hell with what I have. As long as I can run 45s! I agree the price commanded for the WE 274b is insane! Personally, I found a RCA 5u4g I got off Ebay for a few bucks the "best" IMS. I'm listening to a 1943 RCA 5v4 right now. I have two other's like it but this one has a single plate (looks like a 27 or 45) whereas the other two are bi-plates. All three have the signal square getter. The 5u4 seems to synergize better with my system (slightly fuller bass) where the 5v4 is somewhat leaner but Man, what detail - spooky!

respecfully,

MikE

[WildWest]

Yeah Mike, thanks a lot! I saw that one on there in fact. I would like a metal base but it does appear to be at the end of it's life and for 80 bucks ummmm naaaaa

Was it misunderstood my looking for a new rectum fryer tube as wanting a better sound? Did I say that? I want a nice nos mullard for its better performance in the overall picture of my amp and it's slower warm up characteristics. Also want one for the mere "look" of it ya know? :D

[Rob]

WW,

That was my doing bringing up that whole issue. I saw the auction post and went and had a peek. When I saw $80 already and the weak condition I thought, "Groan, here we go again", and just had to say something.

Rob

[Thatch_Ear]

I am being a good boy and staying away from Vintage, though I must admit I miss Thor, but I want in on this. Your power supply can make or break your gear. Cheap power supplies make for not so good sound and can even dump noise back into the line to foul up your other componants. A rectifier tube is a diode. Not all diodes be they tube, silicone, germanium or selinium are created equal. I am being taught how to tweak CD players. One of the 1st things you do is replace cheap diodes. As well as cheap power cords and filter caps etc. I know that the rectifier is not in the signal path but often only one stage of the filter cap is along the current flow from the rectifier, through the output transformers and into the plates of the power tubes. Since the filter cap is to ground the only thing that the electricity actually goes through before the output transformer's primaries and the power tubes plate is the rectifier it makes sence to me that it aught to affect sound quality.
Now hopefully whomever bought that Mullard GZ34 just is a crazy collector and liked the metal base and the quality of the logo.
As to whether or not the rectifier can have a posotive or negative result in the sound coming out of your speakers I would say yes it does. And like other hollow state devices I would also venture to say that manufacturer and materials used will make a difference even between 2 of the same type that measure the same on a tester. It just seems like a reasonable assumption to make. Hopefully the reason some rectifiers are worth more than others is from listening to them in the circuits. I doubt that Dynaco and Heathkit chose Mullard 5AR4s over GEs is because of price. Just as those kits tended to come with Mullard power tubes and Telefunken 12AX7s in a lot of cases.
Besides that, Greetings and Salutations. I am back to Karma and hopefully won't raise the hackles of those I upset before.
Thatchmo
PS I try to get at least 2 sections of the filter cap and a choke in the path to smooth ripples before sending it on to the OPT. Hopefully that helps to make the quality of the vacuum diode less of an issue.

[MikE]

I'm very much subjectivist oriented and not overly interested in the more objectivist principals and theories of a electronic signal. Call that stupid or not, I'm just being honest. Perhaps it's my Eastern culture, that it is more important that something IS than the WHY it is. I listen and report what I hear, as to why I hear what I do or the cause is not as important or certainly as interesting, least to me. So I don't know why I heard a difference between the rectifier tubes, but regardless of why or what that may say about the quality of my components I heard it. Thanks for chimming in.

Everything seems to be back to normal, Thoots is back moderating Vintage with a set of "posting ground rules or guidelines". Did you see that post? It seems fair to me. They are just being honest that they are not particularally interested in hearing about tubes and SET and cables-n-such on the VINTAGE FORUM. That that is why we have a Tube Forum. Hey, I realize this is a Vintage-driven forum so I'll respect the request. NO SET BOMBS on the Vintage board, no probs.

MikE

[Thatch_Ear]

I promise not to make any remarks about tubes, cables or anything of any importance at all in the vintage board. And I am going to help Thor build his keg speakers if I can. I sent him a couple of ideas for him to check out.
Thatch