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Some quick questions on Zen Decware EL84 SET schematic
Some quick questions on Zen Decware EL84 SET schematic
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Old 10th July 2020, 11:20 PM   #11
Windcrest77 is offline Windcrest77  United States
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Some quick questions on Zen Decware EL84 SET schematic
Yeah I'm looking at other EL84 SE switchable to SET amps. I want to see what all the hub bub is with 2 watt 6BQ5 amps and a high efficiency speaker. Hoping for some nice late night listening with my wife. The RH84 has been mentioned here and in May another member was asking for a list of EL84 SE amps, all helpful. In any case even not knowing the exact amp I can machine my top plate because I'll use parts I have.
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Old 10th July 2020, 11:21 PM   #12
mboxler is offline mboxler  United States
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Originally Posted by Windcrest77 View Post
There is a cult-like following of this little ZKIT amp, audio nirvana apparently, all the typical audiophile jabber from its followers. This is what attracted me to such a simple build, already having all the parts, I was looking for a quick project to use with my 96db speakers in a spare room here. But the mistakes in the schematic leave me wondering. If anyone has a reliable schematic, that would be pretty cool.

Zen Triode SET kit amplifier model ZKIT1
Here's one from 2011...

ZKIT1schematicrev2011.pdf

Mike
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Old 10th July 2020, 11:44 PM   #13
mp9 is offline mp9  United States
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Originally Posted by Windcrest77 View Post
-
I'll be using this low-watts amp with a pair of Klipsch RP600M speakers (96db at 2.83V / 1m) and an 8 inch powered sub woofer coming off the speakers.

https://f072605def1c9a5ef179-a0bc3fb...-Sheet_v01.pdf
FYI, Klipsch RP600M is not 96dB, $tereophile measured it and estimated 89.6dB. I experienced the same prior to that article when I took home a pair from a local BestBuy to try with a 8watt 300B SET amp and found they required about the same gain as a pair of 88dB speakers with a minimal parts simple 1st order crosover and easy impedance that I had on hand.

Klipsch Reference Premiere RP-600M loudspeaker Measurements | Stereophile.com

More on Decware:
YouTube

YouTube
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Old 11th July 2020, 12:59 AM   #14
planet10 is online now planet10  Canada
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Some quick questions on Zen Decware EL84 SET schematic
The scema in the 1st post references Edcor transformers. AFAIK Steve makes his own OPTs at least.

We did clone the amp, but then kept making it better. Start with somethign like the RH84 or one of the developments on it.

dave
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Old 11th July 2020, 01:25 AM   #15
audiowize is offline audiowize  United States
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You should definitely *not* use the same cathode resistor for both channels. This will absolutely cause channel separation issues. In the last amp I had in for service that had a shared cathode resistor in the output stage, I saw only 40dB of channel separation. I was not Inspired.
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Old 11th July 2020, 04:13 AM   #16
Windcrest77 is offline Windcrest77  United States
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Some quick questions on Zen Decware EL84 SET schematic
Quote:
Originally Posted by mp9 View Post
FYI, Klipsch RP600M is not 96dB, $tereophile measured it and estimated 89.6dB. I experienced the same prior to that article when I took home a pair from a local BestBuy to try with a 8watt 300B SET amp and found they required about the same gain as a pair of 88dB speakers with a minimal parts simple 1st order crosover and easy impedance that I had on hand.

Klipsch Reference Premiere RP-600M loudspeaker Measurements | Stereophile.com

More on Decware:
YouTube

YouTube
Thanks,

I suspected that the RP600 probably wasnt really a 96db speaker, based on its size, but it does play considerably louder than my Golden Ear bookshelf speakers and those are truly rated at I think 86db. I was looking for a budget speaker for a 12 x 12 room we like to sit in and just relax and listen to music late with no TV on in the dark. The RP600 is a fun speaker, I'm not into laid back speakers, my wife and I attend AXPONA every year and I'm only satisfied by horns year after year. Maybe its my aging ears, but I'd rather have a speaker I have to tame rather than laid back one that is "theoretically" perfect in measurements. True the RP600 is small and its a wave guide not a true horn, but at $600 a pair it had the fun factor, and it works good with tubes in a small room. Frequency response flatness, impedance dips, etc mean less and less to me as I get older. The acoustics bother me more than speaker inaccuracies, I'm done with speakers that are "perfect" but dull, no fun.

I considered doing the RP600 crossover modification kit that GR-research sells, but I really don't think my listening will be improved, it will just be different. I've paired these with a small 8 inch Golden Ear subwoofer and am happy in this 12 x 12 foot room. So far I'm pretty confident the RP600's will do well with a 2 watt amp which is why I'm looking to do an EL84 SET.

As for the Zen videos, thanks. I see this Guttenberg guy at AXPONA every year on the elevators, walking around, everyone seems to know him there, I always wondered who he was! And I see this guy likes the RP600 and commented about wanting to pair them with a Zen Decware, mmmm.

Last edited by Windcrest77; 11th July 2020 at 04:28 AM.
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Old 11th July 2020, 04:48 PM   #17
6A3sUMMER is offline 6A3sUMMER  United States
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Post # 12:

There are no B+ bleeder resistors.
Safety First!
Prevent "The Surviving Spouse Syndrome"!

There are no dividing resistors across the two stacked 20uF B+ caps.
If you already have the two 20uF caps, then use a pair of resistors to divide, and to act as a bleeder too.
Or, replace the two 20uF with a single 10uF @ 500V, and put a single bleeder resistor across it.
Done.

The 6N1P has about 2 times the plate resistance of the other 2 tube types.
The 6N1P has about 1/2 of the transconductance of the other 2 tube types.
The 6N1P has about 1.5 times the filament current of the other 2 tube types.
Other than that, the 6N1P is similar (only similar specs are the mu, and the pinout).

Caution:
The SV83 screen is only rated for 200V Maximum.
The EL84 and 6BQ5 screens are rated at 300V Maximum.

The black wires on the output transformers (Speaker Out Common), need to be grounded.
Safety First!
Prevent "The Surviving Spouse Syndrome"!

Someone else can find any remaining errors, if there are still some.

Last edited by 6A3sUMMER; 11th July 2020 at 05:03 PM.
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Old 11th July 2020, 07:46 PM   #18
invaderzim is offline invaderzim  United States
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Quote:
Originally Posted by Windcrest77 View Post
I'll be using this low-watts amp with a pair of Klipsch RP600M speakers (96db at 2.83V / 1m) and an 8 inch powered sub woofer coming off the speakers.
I know a lot of people use those speakers with low power setups so they must work well enough but keep in mind that, according to Stereophile magazine, their sensitivity is more in the range of 89 than 96. 89 isn't a terrible sensitivity but it is a number that is found in a lot of bookshelf speakers; making them less unique.

"The Klipsch's specified sensitivity is an extraordinarily high 96dB/2.83V/m. My estimate was much lower, at 89.6dB(B)/2.83V/m,"
Klipsch Reference Premiere RP-600M loudspeaker Measurements | Stereophile.com

Then again I'm using 85 db speakers on a 7 watt amp right now and am plenty happy with the output...
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Old 12th July 2020, 12:22 AM   #19
Windcrest77 is offline Windcrest77  United States
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Some quick questions on Zen Decware EL84 SET schematic
Quote:
Originally Posted by 6A3sUMMER View Post
Post # 12:


The black wires on the output transformers (Speaker Out Common), need to be grounded.
Safety First!
Prevent "The Surviving Spouse Syndrome"!

Someone else can find any remaining errors, if there are still some.
All those things yes. But Steve the owner of Decware writes specifically in his literature that the OPT isn't grounded and that is part of the sound, not sure what to make of that, I'll ground it. I was going to use all motor run caps polypropylene in vegetable oil, since all these values are so low, may as well take advantage of that, so no need to series up any caps. I was going to do all that cap paralleling with small caps, I know many say that doesn't matter, I don't know I'll respect the designer. I noticed this designer doesn't like grid leak resistors, rather than have none, maybe I'll just make those 1 meg as though they are still not there but still protect from electron build up. Not sure what schematic you're seeing but some I've looked at have no grid leaks.

The cult following is pretty strong around this little amp. If I like low watt listening with a small sub, them I'm going to look into building a pair of 8 cubic foot 15 inch full range speakers at 104db. I can do those for under $1400 a pair using the Audio Nirvana alnico classic 15 speakers. Then I'll be all set till I die, right. Full range because crossover making is something I have no desire to do.
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Old 12th July 2020, 12:28 AM   #20
Windcrest77 is offline Windcrest77  United States
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Some quick questions on Zen Decware EL84 SET schematic
Quote:
Originally Posted by invaderzim View Post
I know a lot of people use those speakers with low power setups so they must work well enough but keep in mind that, according to Stereophile magazine, their sensitivity is more in the range of 89 than 96. 89 isn't a terrible sensitivity but it is a number that is found in a lot of bookshelf speakers; making them less unique.

"The Klipsch's specified sensitivity is an extraordinarily high 96dB/2.83V/m. My estimate was much lower, at 89.6dB(B)/2.83V/m,"
Klipsch Reference Premiere RP-600M loudspeaker Measurements | Stereophile.com

Then again I'm using 85 db speakers on a 7 watt amp right now and am plenty happy with the output...
Yeah they are a budget speaker, but they are fun regardless of the midrange dip. I've compared them a/b to a modded RP600 that omitted the midrange dip and I actually still liked the stock design better. I hope to build some 8 cubic foot 15 inch full range 104db speakers, maybe this fall.
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