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Safe rectifier roundup (Decware input pending) (Read 10258 times)
hifitubes
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Safe rectifier roundup (Decware input pending)
07/04/12 at 07:49:22
 
Preferred Series 274B

The Preferred Series 274B tube is a full-wave rectifier that is very similar to the classic 5U4G. This 274B tube's filament draws 2.5A of current. This current draw makes it acceptable for many amps originally designed for a 5AR4/GZ34 tube. Our PS-274B tube is a beautiful large coke bottle shaped rectifier tube with large black plates. Space may be an issued in some amps so be sure to check this.

Note - ISSUES REPORTED WITH WOO AMPS The tube emitted flashes, it turned out the first cap value is 330uF which is a lot higher than what is required to run a Sophia 274B or EML 5U4G.


GZ32

(5V4G=83V, GZ32=5V4G, 5V @ 2.3A Filament, PIV=1540V, Imax=175ma, Max Capacitance=60uf)

The 274B should be okay as should be the GZ32 imo.
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« Last Edit: 07/04/12 at 11:28:03 by hifitubes »  
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Steve Deckert
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Re: Safe rectifier roundup (Decware input pending)
Reply #1 - 07/05/12 at 18:38:32
 
Decware amps typically use between 33 ~ 47uf caps as the first section of the power supply filter after the rectifier tube.

In the case of the SE34I.3 the value is 47uf.

So far all the 274B's I've looked at ( and I haven't looked at all of them ) would like to see less than 10uf as the first section of the power supply filter.  Going beyond the value could cause flashing upon startup.  That said, many people ignore the warning and use it anyway, claiming the sound is worth the potentially short-lived tube.

Steve
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hifitubes
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Re: Safe rectifier roundup (Decware input pending)
Reply #2 - 07/07/12 at 05:59:06
 
Thanks Steve.

The EML 5U4 mesh plate spec. is: max value for capacitor, connected to plates - 33uF.

Interesting as some GE data sheets show 40uF for 5U4 as typical.

thanks
jon
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Rivieraranch
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Re: Safe rectifier roundup (Decware input pending)
Reply #3 - 07/07/12 at 13:33:41
 
I am curious as to how one of these mesh plate rectifiers sound. Would they be that much better than a good NOS 5U4G?
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orangecrush
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Re: Safe rectifier roundup (Decware input pending)
Reply #4 - 07/07/12 at 16:28:49
 
Emmision labs state either a max capacitor of 33uf or choke loaded. Don't most Decware Amps have chokes?
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orangecrush
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Re: Safe rectifier roundup (Decware input pending)
Reply #5 - 08/04/12 at 19:12:27
 
Anybody know what the cap value is on the Torii?
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Les Lammers
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Re: Safe rectifier roundup (Decware input pending)
Reply #6 - 10/15/12 at 17:45:33
 
I am curious as to how one of these mesh plate rectifiers sound. Would they be that much better than a good NOS 5U4G?

At $240 each it would be an expensive coin toss.  

I have quite a few 5U4G's and will put them on the classifieds soon. I've had them for years and will likely never use or need them. I'm a recovering tubaholic.  ;)
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Rizlaw
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Re: Safe rectifier roundup (Decware input pending)
Reply #7 - 01/10/13 at 16:42:13
 
I've been following this particular thread with interest since I have a SE34I.35 on order. Unfortunately, while I love tubes I'm not well versed on the technicalities as they apply to safe rectifier tube rolling in the SE34I.3.

My understanding of Steve's 1st reply to this post, is that the SE34I.3 has a capacitor value of 47uf and he doesn't recommend using the EML 274B rectifier tube because, in his experience, many 274B type tubes want "to see less than 10uf as the first section of the power supply filter." Ignoring this fact could lead to premature failure of a very expensive tube. From Steve's point of view an EML 274B is not a safe tube to use in the SE34I.3, or any other Decware amp with higher capacitor values.

What I'm unclear about is whether the EML 5U4G mesh plate, which, according to EML's specs, wants "the first capacitor connected to plates to be 33uf" also falls into the same unsafe catagory. http://www.emissionlabs.com/datasheets/EML5U4G.htm  since the SE34I.3 uses a 5U4G rectifier at 47uf, albeit, not an EML mesh plate.

Does this mean that even though the EML tube is a "5U4G" tube that it can not safely be used in the "Rachael" which uses a 5U4G rectifier? If so, why? I'm confused about this.

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« Last Edit: 01/10/13 at 16:43:54 by Rizlaw »  

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Lord Soth
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Re: Safe rectifier roundup (Decware input pending)
Reply #8 - 01/10/13 at 17:30:13
 
To use an analogy, think of the max uF of the rectifier as blowing up a balloon. Every type of rectifier has a max uF limit specified in the tube data sheet. If the amp uses a higher uF than the maximum limit of the tube, you are over blowing the ballon and over stretching it. This stress will cause the ballon to explode.

Ermmm, hope that helps.
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Rizlaw
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Re: Safe rectifier roundup (Decware input pending)
Reply #9 - 01/10/13 at 17:58:18
 
Thanks Lord Soth for the analogy.

If I understand your analogy correctly, that means that we can not use an EML 5u4g tube spec'd @ 33uf in a Decware SE34I.3 integrated amp which has a 47uf cap. The tube would spark, which is bad and also voids the EML warranty. This, in turn, seems to mean that not ALL 5u4g brand tubes are electrically interchangable in an amp designed to use 5u4g rectifiers like the SE34I.3. This just sounds wrong to me. But, it still doesn't explain why any true "5u4g" tube would not be electrically identical to any other 5u4g tube and a "no worries" drop in replacement.

Is it the mesh plate design of the EMLs, or are variations in the spec perfectly permissible?

Looking at the Decware Factory Tube replacement page http://www.decware.com/newsite/tubesets.htm the Ruby brand 5u4g is offered, but no specs are noted regarding capacitor rating.

How disappointing. Say it ain't so Steve. Cry
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marky
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Re: Safe rectifier roundup (Decware input pending)
Reply #10 - 01/10/13 at 18:28:01
 
I understand the point. Seems like all the old NOS 5u4`s were similar spec and the EML comes along, same...but different...but why ? They must be aimed at a particular amp family. I see they dont make a mesh EL34 but do make a mesh 300B and 2a3. Could be the clue.
I`ve been reading a few forums on them and it`s the same story, if you use them they wont last long with the 47uf.
I`m interested because I still haven`t decided what pair of rectifiers to go for on 2 Rachaels.
So far I`ve bought old nos Tesla mil EL34`s and b/boy 6dj8`s.
Not to expensive so far. The EML`s would seem like overkill.  :)
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« Last Edit: 01/10/13 at 18:33:09 by marky »  

Decware: Rachaels x 2 bridged, CSP2+, ZP3, ZMC1, DSC i/c`s, DHC-1 pw/cbl`s. Roksan Radius/Nima/high def cabl & M.Benz LP s , M/L aeon i`s, Townshend Isolda sp/cbl`s, Isotek mains sub
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Lord Soth
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Re: Safe rectifier roundup (Decware input pending)
Reply #11 - 01/11/13 at 03:14:06
 
Yes.

In the old NOS days, there was an industry standard which major manufacturers adhered to.

The new vacuum tube manufacturer has deviated from the industry standard for 5u4g rectifier.
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Rizlaw
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Re: Safe rectifier roundup (Decware input pending)
Reply #12 - 01/11/13 at 20:08:45
 
Lord Soth,

You may be correct on this, but EML's data sheet for the 5U4G makes it clear, or so I think, that the tube "is a direct replacement for the historical 5U4G" http://www.emissionlabs.com/datasheets/EML5U4G.htm notwithstanding the 33uF upper limit. I suppose the question is, what do they mean by "historical". They provide old chart info at the bottom of the data sheet which I don't even begin to comprehend.

I have sent an email to Emission Labs asking them to clarify if their 5U4G is suitable for the SE34I.3. I hope they respond favorably. I sent a similar email to Steve and he responded very quickly: he' can't say for sure because he has never used the EML 5U4G.

EDIT 1/11/13, 6:00 pm:

O.K., I just received EML's response to my email this afternoon.
Here it is in bold type:

"the 5U4G is originally specified for maximum 32uF.
5U4GB is 40uF.  You can recognise it by the cilinder glass.

I see this amplfier pictured with 5U4GB.    There are
often cases people are not aware of the
difference between 5U4G and 5U4GB.

So if someone uses 47uF  that is out of specifications, and
the limit is 33uF.

One should not design an amplifier by "not having trouble"

If it is wrong,  it is just not right,  and that is where
we are with 47uF.  

For cost reasons,  you do often see this 33uF exceeded,
but it's a not so nice game,  and it's on the risk of the
owner.   We have to deal with amplifier builders who
know this, and some who don't know this.  Both are
not easy to deal with.   The Decware SE34I.3  never
had any problem reported, so I suppose we should
leave it out of the problem list.  I think  probably it will
work,   this is just my feeling.  But it's on you own risk.

You can ask any of the NOS dealers if they will
replace a broken RCA tube you used it one year
in some small overload condition.  I don't think they
do that. Guarantee is only very short on NOS tubes.  

However at EML we want to give you one year guarantee,
but that requires correct use of course.    Sorry for
being the bad guy, but  good use comes first.    I hope
you understand it.

Best regards,
Jac"


So, I guess if anyone tries it, and it fails, you're out $230.00. Cry
BTW, in the 2nd paragraph of his response, I think he is referring to the picture of the SE34I.3 with a 5U4GB rectifier on the Decware "Amplifiers" homepage. If you blow up the image, you can see a 5U4GB straight bottle tube. I was a little surprised by this, but I don't think its an EML tube because EML doesn't make 5U4GB tubes.
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« Last Edit: 01/11/13 at 23:21:00 by Rizlaw »  

System 1: Computer/Linux OS > Audiophileo 2 > W4S DAC-2 > Woo WA-2 / CSP3 > Taboo III > Omega 3E / LCD-2.1/ Beyer DT-990/DT-1350
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Lord Soth
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Re: Safe rectifier roundup (Decware input pending)
Reply #13 - 01/12/13 at 01:55:59
 
The old NOS tubes made by major manufacturers such as Tung Sol, Mullard or Telefunken were often designed to be able to take more punishment than their official specs. Hence they are more rugged than new production tubes.

The EML is overpriced to me.

At those kind of prices, I'd rather get a trusted NOS tube.

BTW, I suggest trying the Philips 5R4GYS from upscale audio as a replacement for your 5U4G rectifier. It only costs $45. There are glowing reviews over there and I have experienced it for myself.
If that works out for you, the Brimar 5R4GY will definitely sound even better in your setup.

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Rizlaw
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Re: Safe rectifier roundup (Decware input pending)
Reply #14 - 01/12/13 at 03:32:11
 
Lord Soth,

I agree the EML is expensive, but it looks beautiful and it is hand made. The EML would visually complement the Treasures I've also ordered from Steve for the Rachael. Genuine NOS Brimars or RCAs are at about the same price points as the EML at most of the online tube retailers, if and when you can find them!

I spent a few hours surfing the web today for 5AR4 variants and I came upon a thread on Upscale Audio's website which pointed me to your mini-rectifier-shootout. http://www.audioasylum.com/audio/tubes/messages/24/248138.html Nice work and helpful.


Since my "Rachael" won't be ready for, at least, another 8 weeks as far as I can guess-timate, I am reluctant to buy a couple of those Phillips rectifiers since I have no way to test them until the Rachael arrives. I'd hate to spend $$$ now and find out 2 months from now that what I bought was damaged with no recourse. Upscale only offers a 30 day warranty. I'll have to hope they are still available when I'm ready.

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System 1: Computer/Linux OS > Audiophileo 2 > W4S DAC-2 > Woo WA-2 / CSP3 > Taboo III > Omega 3E / LCD-2.1/ Beyer DT-990/DT-1350
System 2: Yamaha PX-2 (Shure Ultra) / Oppo DV983H > Classe CAP2100 > Thiel 7.2
System 3: Fisher:R200/X202B > Magnapan MMG
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marky
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Re: Safe rectifier roundup (Decware input pending)
Reply #15 - 01/12/13 at 12:16:55
 
I finally ordered the philips rectifiers and reading L Soths observations
in the above were very helpful in decision making. In fact I`m getting
warmed to the Philips brand. The miniwats always look enticing.
Riz, I did read that a user of the EML got 600 hrs out of the tubes before they went on the blink whereas they should last 1000`(s) +. So you could take a flier, if it`s just the tubes that go and no damage elsewhere....
In the info they provide they mention some component changes inside the amp and also they had to change or add extra heaters because of problems. I think if you wait they will eventually fix all the bugs.
Lotta money for a punt.
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« Last Edit: 01/12/13 at 12:22:23 by marky »  

Decware: Rachaels x 2 bridged, CSP2+, ZP3, ZMC1, DSC i/c`s, DHC-1 pw/cbl`s. Roksan Radius/Nima/high def cabl & M.Benz LP s , M/L aeon i`s, Townshend Isolda sp/cbl`s, Isotek mains sub
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JD
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Re: Safe rectifier roundup (Decware input pending)
Reply #16 - 01/12/13 at 16:07:52
 
those phillips are a great rectifier you won't be disappointed.  I have to say that my fav rectifier so far is nos 1953 rca 5r4gy that i picked up from cryoset that is currently in my csp2+.  Running early 50's rca 5u4g rec's on my torii.  240 seems too much to spend on a rectifier.  money might be better spent on a couple great nos input tubes...telefunken, amperex,mullard, ediswan etc.

JD
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Rizlaw
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Re: Safe rectifier roundup (Decware input pending)
Reply #17 - 01/13/13 at 01:02:17
 
My mind is melting with this 5U4G rectifier issue.

I just went back to the EML 5U4G technical spec page. As I posted yesterday (Reply 7 & 9), EML spec'd their 5U4G at "33uF for 1st capacitor connected to plates" (that was on Jan. 11, 2013).

I also posted the email response I received from EML's Jac van de Walle where he confirmed the EML 5U4G had a max capacitor value of 32/3 uF and the 5U4GB (an electrically different tube) was 40 uF (see my Reply 12 this thread).

This evening, Jan.12, 2013, I went back to the same EML spec page and guess what, EML changed the max safe capacitor value for the 5U4G from 33 uF to 40uF! I sure wish I had saved a copy of yesterdays EML 5U4G web page. So maybe they caught an error because of my inquiry and fixed it? Fair enough.

But, according to Mr. de Walle's email of 1/11/13, the 5U4G and 5U4GB are electrically different tubes, so how can they have the same capacitor value when he stated different values in his email to me? Perhaps another error regarding the 5U4GBs correct max capacitor rating?

As Mr. de Walle's email also mentions, the photo of the SE34I.3 on the Decware site shows a 5U4GB rectifier being used.

So as Dr. Szell (Laurence Olivier) asked Dustin Hoffman in "Marathon Man": "Is it Safe?" the EML 5U4G that is.

P.S. I'd prefer not to have my teeth probed without anesthetic on this one. Grin
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System 1: Computer/Linux OS > Audiophileo 2 > W4S DAC-2 > Woo WA-2 / CSP3 > Taboo III > Omega 3E / LCD-2.1/ Beyer DT-990/DT-1350
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clowkoy
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Re: Safe rectifier roundup (Decware input pending)
Reply #18 - 01/13/13 at 10:04:57
 
There is actually a very simple solution to your problem: change the first capacitor to a polypropylene 3.9uf, like a Mundorf or Clarity cap. I've done this on my CSP2+ to accept a Sophia 274b. I didn't hear any difference in sound or increase in hum. A polypropylene cap is much better than those $2 stock Lelon caps. A mundorf costs $90.
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Rizlaw
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Re: Safe rectifier roundup (Decware input pending)
Reply #19 - 01/13/13 at 19:14:05
 
Clowkoy, my apologies in advance for this long winded reply. It's more, or less, a summary of everything I've said before and where, in my thinking, I'm at now on the subject. I'm hoping it will be my last post on the subject.

Quote:
Clowkoy
There is actually a very simple solution to your problem: change the first capacitor to a polypropylene 3.9uf, like a Mundorf or Clarity cap.


Clowkoy, the problem to which you refer (rectifier tube/amp compatibility) IMO, is not just my problem, it's a problem for anyone who owns or contemplates purchasing a Decware SE34I.3 and contemplates tube rolling. At this point, at least for me, the jury is still out on whether it's the amp or the particular tube that's at the rooThere is no mention of any other type of 5U4 tube, i.e., 5U4GA, GBt of the problem in the first place. This is assuming there is a problem at all! Until I hear more from Steve, I shall reserve judgment. (skip to the last paragraph if you don't care to read any further)

As for replacing caps, that, IMO, could and probably would void the lifetime warranty, not to mention compromise Steve's intended design goal for this amp. While I may be somewhat ignorant about the internal workings of tube electronics, I get the feeling that changing a cap in a preamp is less problematic (read dangerous) than doing so in a power amp.
There is no mention of any other type of 5U4 tube, i.e., 5U4GA, GB
In the end, I have to believe that Steve knows how to build a proper amp for the tubes he selects and that he knows how to select caps with proper values so that those tubes operate correctly, within their intended specifications (NOS or current tubes), and without flashing issues (all this, notwithstanding what EML's Mr. van Walle implied in his email to me yesterday. See Reply #12 above).

Carefully reading the the Decware web site "Specifications" on rectification for the SE34I.3:

Quote:
Rectification    5U4G tubes


There is no mention of any other type of 5U4 tube, i.e., 5U4GA, GB
and the pdf "Owner's Manual" for the SE34I.3 "Rachael":

Quote:
There are also some compatible substitutes that you can try which include 5Y3GT and
5AR4. The 5AR4 is an indirectly heated rectifier with a soft start up so it may be a bit
more expensive than the 5Y3GT and 5U4. A popular rectifier tube that many people try
to substitute is the 274B. There are different manufactures and different types of 274B
rectifier tubes. Of the ones we’ve examined, they all required no more than a 10uf
capacitor in the first section of the power supply. Very few tubes amps today use that
small of a value. The SE34I.3 uses a 47uf capacitor in this location which can cause
the 274B to arc on start-up and thus reduce it’s life.


you now know the following:

1. the substitute rectifier tubes which could be a problem are some 274B's. A list of know problem 274B is not given;

2. the 5AR4 or 5Y3GT tubes are compatible substitutes for the 5U4G; and

3. any "5U4G" tube will work (NOS or current) since there is nothing in the manual or spec that states otherwise similar to the caution on the 274B. There is no mention of 5U4GB which is not electrically the same as a "5U4G", although, I think, it does appear to be safe to use from everything I've learned so far. We need Steve's confirmation on this.  

What set me off on this journey was the OP's original question concerning "safe" rectifier substitutions for the SE34I.3 "Rachael". The OP wanted to know if it would be safe to substitute a 274B in place of a 5AR4/GZ34 AND his important notation of flashing problems in WOO amps which used the Sophia 274B and EML 5U4G.

To be clear, nowhere in this tread has it been stated that an EML 5U4G will flash and prematurely fail in the SE34I.3. The closest anyone in this thread has come to "suggesting" premature failure for the EML 5UG4, was "Marky" in replies #10 and 15 concerning what he read regarding the EML 5U4G tube on "other" forums, possibly with other non-Decware amps.

Nevertheless, the only reason I posted anything in this thread was because of the warning about tube-flashing of "EML 5U4G" tubes. I asked myself: why would the EML 5U4G flash in a Decware "Rachael" which is designed to accept a "5U4G"? By "a 5U4G" I am only referring to that specific tube, not to 5U4GA or 5U4GB.

When I looked at the EML 5U4G max capacitor spec on the EML web site, it was originally noted to be 33 uF and in less than 24 hours was quickly changed to 40 uF (as I noted in a post above). Both of those values were below Steve's selected cap value of 47 uF. Was this a potential flashing problem? Maybe. Lord Soth's "ballon" analogy in reply #8 on page 1, which explains how a tube can be stressed when used with a capacitor rated higher than the tube's max capacitor specification added to my concern. Adding more confusion, was the fact, pointed out by EML in their email to me, that the picture of the Decware SE34I.3 showed not a 5U4G, but rather a 5U4GB, an electrically different tube with a 40 uF cap rating. The 5U4GB is still 7 uF below the SE34I.3s 47 uF cap. Is this a problem or not?

Recognizing that tubes are tempermental beasts, and can fail at any time and for almost any reason, I am at the point of asking the following questions:

1. If the 5U4G and 5U4GB are electrically different tubes, are they safely interchangable (NOS or newer current types) in the "Rachael" in the same way 5AR4s or 5Y3GTs are safe substitutes? If not, why not?

2. If the "Rachael" is using a 5U4GB as the stock tube, rated at 40 uF max according to EML, why isn't this noted in the specifications to avoid confusion?  Steve has confirmed in an email that the rectifier he is using (without exactly specifying the model tube) is working without issues, but he can't confirm that the EML 5U4G will work because he has never tested it in the Rachael. Excluding a bad tube, why wouldn't an EML 5U4G work properly? It seems to me the specifications should state which of the 5U4 family of tubes is safe to use.

So, in the end, I believe what is needed for the SE34I.3 is more and clearer information from Steve himself. Much akin to what he provides for the Mini Torii information page (pictures and descriptions of all the compatible tubes).  
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System 1: Computer/Linux OS > Audiophileo 2 > W4S DAC-2 > Woo WA-2 / CSP3 > Taboo III > Omega 3E / LCD-2.1/ Beyer DT-990/DT-1350
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clowkoy
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Re: Safe rectifier roundup (Decware input pending)
Reply #20 - 01/13/13 at 23:41:02
 
If you really want to follow the capacitor requirement, then you only have the 5AR4/GZ34.

"So, in the end, I believe what is needed for the SE34I.3 is more and clearer information from Steve himself. " - Good luck on this. Sad
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marky
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Re: Safe rectifier roundup (Decware input pending)
Reply #21 - 01/14/13 at 00:20:03
 
This is asking questions about tubes that I haven`t got involved with on the spec sheets.
I`ve bought 12ax7`s, 12au7`s, 5u4`s, 5y3`s, 5ar4`s, and 5r4`s with all sorts of different suffixes....I just buy them put them in. So far no prob.
When I read here about the 247b`s I thought wow, yeah, must get one, they`re huge. But...they came with baggage, as in the brightest light burns half as long..possibly. I still check them out, out of curiosity. Then a couple of months ago the mesh rectifiers were mentioned. I couldn`t find them until Rizlaw brought them to light. I thought they would be old NOS at just a bit more cost but they`re new and 3-4 times more expensive.
I must say I was hoping someone would say " Oh, I use them and ...."
Are they the only makers of mesh 5u4`s ?
How new are the mesh tubes ?

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Decware: Rachaels x 2 bridged, CSP2+, ZP3, ZMC1, DSC i/c`s, DHC-1 pw/cbl`s. Roksan Radius/Nima/high def cabl & M.Benz LP s , M/L aeon i`s, Townshend Isolda sp/cbl`s, Isotek mains sub
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Rizlaw
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Re: Safe rectifier roundup (Decware input pending)
Reply #22 - 01/14/13 at 01:27:52
 
Clowkoy,

I see you don't have faith that Steve will provide additional clarifying info. I'm sure he's a very busy fella and can't read and respond to every issue/ question posted on these forums, even though I think this topic deserves his additional attention.

I left a message on Friday (1/11/13) for him to call me about this, so far he hasn't, but I was told he was busy with a customer and Fridays are a bad day for everybody. Monday they are closed. Perhaps on Tuesday he will call. He's already told me via email that he can't comment on the EML 5U4G because he's never personally used one in the SE34I.3. When I speak to him, I'm sure he will answer and explain the concerns I have outlined in my previous "long" post.

Marky,

Decware forums don't appear to be all that active so I doubt you're going to find an answer about the EML tube here any time soon. It's just too expensive for most people to chance buying and getting an instant flash over with possibly no warranty recourse because EML thinks Decware's circuit topology for the 5U4G tube is faulty. The customer would be caught in the middle of an argument between two manufacturers, both claiming it's the others fault. I'm sure we've all "been there, done that" before in other areas.

However, as EML's Mr. van Walle mentioned in his email to me, it should work and my question to him seems to have immediately prompted a changed in the cap value from 33 to 40 uF on EMLs website for this tube. So maybe we're all worrying about nothing; maybe not.

I may just be crazy enough to eventually buy the EML 5U4G and try it after I get my own "Rachael". In the meantime, I will be ordering a couple of 5AR4s from Upscale Audio on Monday. I was wrong, it seems Upscale gives a 90 day warranty on tubes (not 30) so when I order tomorrow, I should be covered until about mid April. Hopefully, I'll get my amp in March and have a few weeks to spare for testing.
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Re: Safe rectifier roundup (Decware input pending)
Reply #23 - 01/14/13 at 02:15:53
 
There are infamous tube equipment which literally eat tubes.

AFAIK, Decware amps are not designed like that.

The cap values used in their amps is pretty standard and tube friendly so you can literally pop in any of the standard NOS rectifiers such as 5Y3G to 5R4 to 5U4 to GZ34 .... Etc. Those few uF will not make any difference so quit ya yammering will ya? Wink

BTW, the ultimate rectifier is a GEC U52 or the Western Electric 274b.
These have a lower maximum uF cap rating than the standard 5U4, 5Y3 rectifiers used today. I believe that Steve designed his amps to sound fantastic based on good old American made standard rectifiers which were (and still are) cheap and easily available.
Case in point is the CSP2 amp, the US$20 5y3 sounds fantastic in this tube amp.

The cap values also have a bearing on the final sound and so based on what I've mentioned above, I don't see any fault with Mr. D's designs.

If you still insist on using one of those mesh rectifiers, I'd suggest opening a dialogue with Steve to specially accommodate that. The famous Woo Audio also made a special version of some of their amps to accommodate exotic rectifiers like the mesh plates.

However, your final sound output will be different from the original design a.k.a Mr. D's "vision".
The final sound could be better or worse.



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Re: Safe rectifier roundup (Decware input pending)
Reply #24 - 01/14/13 at 02:36:06
 
Anyone know what the cap value is for the Torri?

I am still really liking those cheap Preferred Series Shugang 274B from the Tubestore.
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Re: Safe rectifier roundup (Decware input pending)
Reply #25 - 01/14/13 at 03:23:28
 
LS,

For the record, nothing I have written casts any doubt on the quality of Steve's designs (that was something EML's Jac van Walle seemed to imply in his email to me if his tube didn't work in the "Rachael." He ultimately felt it should work). I wouldn't be ordering a fully optioned "Rachael" if I had doubts.

And yes, I've already quit my "yammering" (although, I thought that what I wrote was better than simple "yammering", perhaps more like "kvetching" when something is not clear enough. Smiley

BTW, I thought you rated the Brimar 5R4GY rectifier #1 and the Philips 5R4GY #2 in your shoot out? I just checked, TubeDepot has the WE 274B for a mere $999.00, which, I imagine, is a non-starter for all but the most prosperous hardcore tube-o-philes.http://tubedepot.com/nos-274b.html

Do you promise, by all the pixie dust in NeverNeverLand that those few uFs won't make a difference. Wink
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« Last Edit: 01/14/13 at 03:26:36 by Rizlaw »  

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Re: Safe rectifier roundup (Decware input pending)
Reply #26 - 01/14/13 at 03:33:33
 
Orangecrush,

I know this isn't a definitive answer to your Torii cap inquiry, but Steve did state that:

Quote:
Re: Safe rectifier roundup (Decware input pending)
Reply #1 - 07/05/12 at 18:38:32  
Decware amps typically use between 33 ~ 47uf caps as the first section of the power supply filter after the rectifier tube.
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Re: Safe rectifier roundup (Decware input pending)
Reply #27 - 01/14/13 at 05:59:36
 
Hi Rizlaw,

Yes, I'm positive that you can safely use any NOS 5Y3, 5R4, 5U4, GZ34 rectifiers in Decware amps. Within each of the major families, there will be a slight variation in uF, e.g. 5U4G vs 5U4GB. This is perfectly fine.

The WE 274b and GEC U52 are really out of the "safe" range wrt uF.

The Brimar 5R4GY retails for around US$100 whereas the Philips 5R4GYS costs less than half of that. From my point of view, they are both Military grade tubes which should be able to last at least 10 years, so the cost is reasonable.
New vacuum tubes don't last as long, hence my personal adversion to forking out 200$++ for the mesh plates.

Now it's me who's doing the yammering. Wink



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Re: Safe rectifier roundup (Decware input pending)
Reply #28 - 01/15/13 at 01:25:01
 
You boys listen to Lord South.
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Re: Safe rectifier roundup (Decware input pending)
Reply #29 - 01/15/13 at 01:56:03
 
And I listen to Mr. Steve D.

;)
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Re: Safe rectifier roundup (Decware input pending)
Reply #30 - 01/15/13 at 17:31:12
 
Hi guys,

Didn't realize this thread was still going like it has.  

I can understand the confusion because we're using 5Y3, 5R4, 5U4, GZ34 (and variants) in our amps with 33uf and or 47uf capacitors in the first stage of the power supply filter.  This is higher than the recommended values on probably all of these tubes spec sheets.  

I designed these amplifiers by ear and that is how these values came into practice.  Also after 15 years and probably 10,000 rectifier tubes, I have only seen a dozen flash during startup.  With these odds of success weighed against the average cost of $40 for a rectifier I feel it's a justifiable risk.

Now, when you start spending hundreds of dollars on exotic tubes, such as the 274B, then I do not feel it's a justifiable risk and that's why I can't recommend it.  Chances are the tube will work fine, just like the more common rectifiers we recommend, but I'm not going to be responsible for them if they have or cause problems.

If you're wanting to use an exotic 274B mesh plate, then we need to modify the power supply to accommodate it.  That means the sound of the amp will change.  The increase in ripple and hum will necessitate additional capacitors down stream which will slow the power supply down, resulting in a different signature for the amplifier.  Additionally, a choke may need to be added (many of our smaller amps don't use one) which may or may not even be possible to do room constraints.

I'm not saying the mods will ruin the sound of the amplifier, it will still sound good, but not the same.

Many of our customers have said "screw it" and used mesh plate 274B's with our stock amplifiers and seem to be getting away with it, but I wouldn't be surprised if the life of the tube is reduced.

So again, if the 47uf first stage weeds out the weak 5Y3, 5R4, 5U4, GZ34 tubes by causing flashing on start up, then who cares... we send you another $40 tube.  If the same thing happens with a EML tube than you eat a $250 tube.

Steve
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Re: Safe rectifier roundup (Decware input pending)
Reply #31 - 01/15/13 at 18:43:57
 
Steve,

Thank you for removing my veil of confusion about this as it regards the "Rachael". I have three more questions:

1a. Notwithstanding cost, which is considerable, does the same caution you give for the mesh plate EML 274B rectifier apply equally to the mesh plate EML 5U4G rectifier with a (40 uF max cap value)?

1b. Does it have something to do with "mesh plate" type tubes, or has it more to do with current tubes vs. NOS tubes?

2. Apart from the two rectifiers (Sovtek 5Y3GT and Ruby 5U4G) you offer, are there other NOS or Current new tubes) in the tube groups you mentioned that have been found to work well with the 47 uF "Rachael"? If so, listing a few would be greatly appreciated?

Again, Steve, thanks for the clarification. I want me "Rachael" straight, thank you. Grin


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« Last Edit: 01/15/13 at 18:44:26 by Rizlaw »  

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Re: Safe rectifier roundup (Decware input pending)
Reply #32 - 02/15/13 at 00:57:05
 
My maxed out "Rachael" arrived today! She looks every bit the elegant lady I expected. I was surprised to see that they added a headphone jack into the front walnut base. I had ordered a separate headphone cable, but somehow the build order sheet got mixed up and they built the jack into the base. No big deal. Steve tells me, apart from his own "Rachael", I'm the first one to get the SE34I.3 with the Jupiter Flat stacked caps. He's quite enthusiastic about the Jupiter caps over the V-Caps. So far, they certainly sound great to me.

The first 30 minutes with the stock tubes was painful listening: flat, lifeless and screechy would best describe what I heard. Fortunately, after 30 minutes, things slowly began to change for the better. It was quite amazing how I could hear the change minute by minute. I can't remember hearing such an obvious auditory improvement of a new component over such a short span of time. Most interesting.

However, two problems immediately became apparent:

(1) The Chinese 5u4g rectifier glass was scary loose from the brown base but the tube worked. Steve's sending a no charge replacement.

(2) a low level hum through my new 94db Omega Super 3Es. Since speaking to Steve, I removed all inputs and left the speakers connected. 30 seconds after power on, a uniform low level hum is audible through both speakers. Steve says there should be no audible hum from 94db sensitivity speakers at 3 feet. If I rule out ground loops, he thinks it could be a bad rectifier. I will have to wait for the replacement rectifier. Also tried using a cheater plug to lift the ground -- didn't work either still have hum.  I also tried several different brands of speaker cables and lengths, no change in hum either. It's going to be a real bummer if I have to return the amp so soon. Shipping this baby isn't cheap. Otherwise, with each passing hour, she's sounding better and better (deep and wide soundstage with very nice satisfying bass w/o sub and good detail, hum nothwithstanding.

I'm also going to order the Philips 5R4GYS rectifier from Upscale Audio to try out and a few months down the road the EML 5U4G.
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Re: Safe rectifier roundup (Decware input pending)
Reply #33 - 02/15/13 at 14:56:41
 
Congrats Rizlaw. Hope you get that hum issue "rectified."

Anyway, a headphone jack, eh? I had said all the Rachael needs is a headphone output to be the perfect integrated amp. Sounds like a great rig.
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Rizlaw
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Re: Safe rectifier roundup (Decware input pending)
Reply #34 - 02/15/13 at 15:37:11
 
Pale Rider,

I agree, a HP jack would be a good option and would make the "Rachael" complete. In my case the HP jack and its placement was actually a "mistake" on Decware's part. But, a "good" mistake according to Steve. Steve said he's been reluctant to add a headphone jack because: (a) he didn't want to drill another hole in the metal top plate and (b) half the folks who want the HP jack also want a speaker cut off (probably me) and half don't. A switch wasn't a good "sonic" choice. So in the end, no HP jack option. Since I don't have a switch to turn off the speakers they will play while I listen to my LCD-2 cans unless I manually disconnect them. Not too big a deal, since I don't listen to my HPs too much.

BTW, for anyone else with a new "Rachael" amp, Steve says you don't need to do the 5 hours on, 5 hours off break in routine noted in the manual. You can play the amp all day long for break-in as long as you turn it off for the entire night.

Edit: apologies for blurry photo below, but old hands and old camera are to blame. Note hole in center front of base where recessed HP jack is located. Also, you obviously can't see in a still photo that the 5u4g Chinese rectifier's glass wiggles, lossey goosey like, where it meets the brown base.

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« Last Edit: 02/16/13 at 04:28:52 by Rizlaw »  

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