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Safe rectifier roundup (Decware input pending) (Read 10936 times)
Steve Deckert
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If the 1st watt
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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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Rizlaw
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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 »  

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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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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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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Pale Rider
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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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Decware: Ultra | Torii MKIII [2] | SE84ZS | Taboo MkIII Sources: Synology 1812+ | Baetis Revolution | PWD DAC MKII | Lumin Network Player | Mytek 192 | Oppo 105 DSP: DEQX Mate | Emotiva Outputs: ERR [6] + Servo Subs | LCD-2 & other cans
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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 »  

DSC00455A.JPG

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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