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Old 16th March 2014, 08:40 PM   #1
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Default 40w Class A PP KT66?

Comments?

DECWARE / ZEN MYSTERY AMP model ZMA

Also, no negative feedback UL.Output impedancemust be pushing into current amp territory.

dave
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Old 16th March 2014, 09:26 PM   #2
multi is offline multi  Australia
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40w Class A PP KT66?
Must be running very hot 40 watts class A?
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Old 17th March 2014, 01:14 AM   #3
12E1 is offline 12E1  United Kingdom
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If I was paying even a quarter of that price I would expect a serious effort to have been made to hide all of the tube socket fixing screws! They also claim that individual tube bias adjustments allows the use of unmatched tubes. It doesn't. It allows tubes with different bias needs to be set to the same level of bias, but it does nothing to adjust for any differences in the slope of the curves. Matching of tubes would still be needed. So, persionally, I am not impressed by the marketing material.

Just my 2 cents...
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Old 17th March 2014, 07:52 AM   #4
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Originally Posted by 12E1 View Post
So, persionally, I am not impressed by the marketing material.


This is sad. You need to develop a taste for "liquid honesty" (which is likely lifted from a whisky ad)

I particularly enjoyed the part where the absence of chokes was so convincingly explained with the addition of big caps.
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Old 17th March 2014, 12:28 PM   #5
12E1 is offline 12E1  United Kingdom
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Quote:
Originally Posted by analog_sa View Post
This is sad. You need to develop a taste for "liquid honesty" (which is likely lifted from a whisky ad)

I particularly enjoyed the part where the absence of chokes was so convincingly explained with the addition of big caps.
Big caps, but only for a while. If they are where I think they are in the pictures, they will be very quickly cooked by their proximity to the output tubes... Once they have degraded sufficiently, the noise from the charging spikes will be no worse than many lower cost amplifiers.
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Old 17th March 2014, 02:47 PM   #6
rmyauck is offline rmyauck  Canada
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Much more affordable class A and you could use KT-66 tubes. Not 40W though, but for sure all class A.

K & K Audio - Lundahl Transformers, audio DIY kits and more

Last edited by rmyauck; 17th March 2014 at 02:54 PM.
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Old 17th March 2014, 05:37 PM   #7
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I particularly enjoyed the part where the absence of chokes was so convincingly explained with the addition of big caps
Read the rest of it carefully.

Quote:
Instead a vacuum regulator tube was used to drop the voltage with no heat and 20 times the ripple rejection of the resistor it replaces. This was a personal goal of mine because it makes this the first tube amp power supply in the world that doesn't use a choke or any current robbing resistors to supply both the input and output stages of the amp. Consequently there is no heat or parts to fail.
Somehow a vacuum tube regulator drops voltage without generating any heat....magic? "The first tube amp power supply in the world" with such design????

We have all seen voltage regulators of several kinds on these page. As far as I know ALL linear regulators will dissipate at least as much heat as the resistor they replace, UNLESS it is a switchmode regulator. A switcher will still dissipate heat, just less than the resistor it replaced. Yes, tube based switchers exist.....or existed. The TEK 504 scope used one.
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Old 18th March 2014, 01:42 AM   #8
syyma is offline syyma  United States
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I will go with George's 6L6GC AB2 route in triode mode. 40 something watts still with big chunk of money in your pocket.

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Old 18th March 2014, 06:53 AM   #9
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According to published specs: +Ub = 410 V, Iidle = 40 - 60 mA,
this is unexceptional AB1-class amplifier.
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Old 18th March 2014, 10:08 PM   #10
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It's DECWARE. That says it all.
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