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The original Zen Triode model SE84C update (Read 3035 times)
Steve Deckert
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The original Zen Triode model SE84C update
01/17/08 at 04:53:07
 
If you want to introduce someone to the world of SET tube amps, the SE84C is a delicious way to do it and with over 1000 in circulation I have decided to make a couple changes to it's design.



Since we are now building these amps with the World Voltage Compatible power transformers I am lengthening the chassis by just over 1 inch to better accommodate the larger size of the transformer.

I am also moving the gain (volume) control to the front center of the chassis to improve ergonomics.



The power switch on the back is being changed from a toggle to a rocker switch for improved durability.

The IEC connector will now be offset just off center leaving more distance between the power cord and the input jacks.

There will be 2 pair of input jacks now instead of one!  That means you can switch between 2 sources!  The switch will be located on the top of the chassis towards the front.

And instead of the industrial gray powder coat finish, it is going to be a jet black high gloss powder coat.

Finally, the amp will be re-biased to use a 5U4 rectifier tube instead of the 5Y3GT.

I'm excited about these improvements, and the amp should go from looking like a fuse box to a beautiful piece of audio gear!

These new chassis should be ready in a few more weeks at which point I'll update the web site and post some pictures!

-Steve  [smiley=cool.gif]




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Re: The original Zen Triode model SE84C update
Reply #1 - 01/17/08 at 22:12:04
 
Wow Steve, those are some great improvements!  I predict this will enhance their allure and maybe increase a bit of sales!
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Re: The original Zen Triode model SE84C update
Reply #2 - 01/17/08 at 22:42:52
 
glad to hear you're still tweaking & improving the classic once again!!  I listened this morning for about two hours to my SE84cs and again marveled at its sound...I love this amp..that's why I have 3!  Keep up the great work ...the only word you need to know in high quality sound is Decware...and the zen triode is a beautiful piece of design......thanks Steve....
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Eli Duttman
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Re: The original Zen Triode model SE84C update
Reply #3 - 01/18/08 at 01:49:45
 
Steve,

I hate to be a party pooper, but a cautionary note is in order.  Russian and Chinese 5U4Gs can be "problem children".  Many times, I've helped 'philes with arcing 5U4G rectifiers.  The solution has always been to use a US made NOS 5U4GB.  Obviously, you have to use tubes that are in current production.  New Sensor sells a Saratov, Russia, made 5U4GB, labeled EH.  Feedback on the EH 5U4GB is anything but plentiful.  It might be a good idea to check the Russian 'GB out for both reliability and sonics.
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Steve Deckert
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Re: The original Zen Triode model SE84C update
Reply #4 - 01/18/08 at 02:36:07
 
Eli Duttman wrote on 01/18/08 at 01:49:45:
Steve,

I hate to be a party pooper, but a cautionary note is in order.  Russian and Chinese 5U4Gs can be "problem children".  Many times, I've helped 'philes with arcing 5U4G rectifiers.  The solution has always been to use a US made NOS 5U4GB.  Obviously, you have to use tubes that are in current production.  New Sensor sells a Saratov, Russia, made 5U4GB, labeled EH.  Feedback on the EH 5U4GB is anything but plentiful.  It might be a good idea to check the Russian 'GB out for both reliability and sonics.


Eli,

The problem no longer seems to be limited to the 5U4G.  In the past year I've had more bad 5Y3GT's (Sovtek) than in the 10 years prior.  But, let's put it in perspective...  Of the last 500 amplifiers that I've sent out the door with 5U4's I've only had to replace a dozen rectifiers under warranty.

I use the Chinese 5U4's because even though the Russian 5U4's look like a far better built tube,  I found the way they made my amps sound to be less than acceptable.  I find the Chinese 5U4's to sound the closest to a NOS G.E. which is my reference.  

Now, I'm not a big fan of Chinese tubes (or anything Chinese for that matter) but in fairness they have come a long way since I got into this business.  I buy all my 5U4's from RUBY.  They sell both "no frills" tubes that basically means little if any grading and they sell Select grade tubes that they put their brand on.  I pay over 3 times the price to purchase his Select grade tubes vs. bulk tubes from China.  I let him weed out the bad ones.

And frankly, that is the game with all tubes, even NOS, in that there are good ones and bad ones in every batch.  The guys with good tubes for sale are the ones who have taken the time to weed out the bad ones.  10% of all the tubes I buy - regardless of who their from - end up in the garbage can.  I don't even try to send them back - too much trouble.  I just look at it as overhead.

One of the biggest causes of tube failure in our case is from the tubes being beat to death during shipping to the customer.  When you pack tubes with a 15 ~ 40 pound amplifier, the G-Force the tube experiences is based on the mass and weight of the amplifier.  If the tubes were shipped by themselves in a separate box, the G-Force would be perhaps 100 times less. This is of course a double edge sword.  But, I look at it as the final test.  If the tube still works when it arrives with an amplifier, it definitely had no undiscovered weaknesses.  If the shipping aggravated the tubes integrity, it will act up within days of going into service at which point we will replace it.  When we send out a replacement tube, it is shipped by itself, without the equivalent of a boat anchor attached to it, so it almost always works.

So as for which tube to use in the new SE84C, I will make the decision based on how I want the amp to sound and how the amp looks with either tube.  Of course, it will still be possible (as it has always been with our amps) to get away with using a 5Y3GT, 5AR4 or 5U4 in any of the amps without harming the sound or the amp.  [smiley=tunes29.gif]

Steve
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Re: The original Zen Triode model SE84C update
Reply #5 - 01/18/08 at 03:11:01
 
Question....
Can the older model SE84CS-EX also take the 5U4 rectifier without modifications or would it require 'rebiasing' to use the 5U4 ?

What improvement would the 5U4 bring?

By the way, when I customized my SE84CS-EX, I also moved the volume control to the front center of the chassis.  I found that to be a good mod.  Glad to hear the new ones will have it too.  Too bad I did not have the space for the dual input connectors !!!
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Re: The original Zen Triode model SE84C update
Reply #6 - 01/18/08 at 03:48:16
 
You can indeed run the 5U4 rectifier(s) in the Select.
                                                                 Don
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Re: The original Zen Triode model SE84C update
Reply #7 - 01/18/08 at 07:08:46
 
Very cool, all rectifier talk aside.

So, this means the SE84C updated with the new chassis, will be available in the good ol' zen kit also?

Karl

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Steve Deckert
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Re: The original Zen Triode model SE84C update
Reply #8 - 01/18/08 at 12:58:19
 
veryoldcat wrote on 01/18/08 at 07:08:46:
Very cool, all rectifier talk aside.

So, this means the SE84C updated with the new chassis, will be available in the good ol' zen kit also?

Karl



Yes it will be available as a kit also  :)
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Re: The original Zen Triode model SE84C update
Reply #9 - 01/18/08 at 21:18:23
 
Steve Deckert wrote on 01/18/08 at 12:58:19:
Yes it will be available as a kit also  :)


*Very* nice! How soon? Wink

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Re: The original Zen Triode model SE84C update
Reply #10 - 01/19/08 at 04:17:50
 
The kit would be a good deal. The two inputs would help in the phono stage input, cause I was thinking of buying the rotary switch box for this. With regards to the 5U4's....... is it that much of an improvement over the 5Y3/5R4 ?? The C does not support the 5U4.


shreekant Smiley
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Re: The original Zen Triode model SE84C update
Reply #11 - 01/19/08 at 17:43:25
 
I think, Shreek, that all you have to do is change one resistor to allow the 5U4's, 5V4's, GZ32's, et al.

If I had the older "C", I'd immediately make that change for the purpose of being able to use GZ32's or 5V4's, as those sound GREAT in the "CS" to my ear, and would sound equally great in the "C", imo.

Karl
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SE84CS (vcapped), CSP, zbox, Dec685, ZP 1.0, Sota tt/Well-Tempered Arm/V15XMR, Parker 98's, Parker Audio *Power Chords*, cat 6 wires, OSX; a garage sale of other stuff...
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