Rerurn to Romy the Cat's Site
In the Forum: Melquiades Amplifier
In the Thread: Planning my DSET
Post Subject: Some perspectives...Posted by Romy the Cat on: 9/8/2019
Anthony,
Yes, the numbers you got are closed to what I expected they shopped
be. Frankly the only concern we have is the Channel A. The in-room response down
to 18Hz is good and trust me there is a LOT of musical content in that 18-30Hz.
A few things I would like you to understand technically to interpret the numbers
you get.
First, your measurements again the “appropriate load resistor” has very little practical meaning. The
drivers is a dynamic system that has impedance not resistance and the impedance
varies with frequency. So, your measurement against 1R might be accurate for 30.5Hz
but might not be accurate at 24.7Hz. So, the proper number at which the clipping
might take place would be observable at the real load, or the real driver(s)
you use. Then there is a definition of clipping. The clipping is situation when
a channel has no power to drive the driver but power is current and voltage.
You should not be concerned about juts clipping but you need to assure a SYMMETRIC
clipping against you real driver across the whole range of the channel. You need
to connect a scope to the channel output while driving your driver and drive a single
frequency from a generator and increase the input voltage. Observe the shape of
the sinusoid and as the input voltage rise you will see that the top or bottom of
the sinusoid will bet distorted, or clipped, or flatted down. The top of the sinusoid
is voltage insufficiency and the bottom of sinusoid is current insufficiency
(or vise versa, I do not remember already). So, you objective should be to get
the absolutely symmetric clipping point when the current and voltage clip at
the same time. Then it means that you get out of you amp the max power again
your given load.
Second important aspect is that
if you deal with an amplifiers then you need to understand when clipping comes
from. If might come from many locations. The PS in driver stage, the coupling
(in case transformers use), or the output stage PS, or the OPT and so on… The Milq
was designed in a way that the any power restrictions are coming from output transformers,
the way how SET should be designed and the DSET topology would take care of
that limitation. So, the primary focus of your in the given topology should be
the only the Channel A output stage. If looks like you beef up enough inductance
in you OPT of the Channel A, which is good, not you need to make sure that you
can pump power to the output tube. Here is there is another limitation. The
6C33C is indirectly heated tube and they type of tube as the enter to the operation
what grid voltage approaches to bias voltage (class A2 or the mode of grid currents)
then this type of tubes do not do so well
and they distort rather hard. The direct heated tubes if you feed them with enough
current they can push through a little bit but the indirect heated cannot. You it should be very important to you that in
your case your Channel A as the input voltage goes up the Channel stags in
Class A1 and the input voltage in the grid of 6C33C does not rise to the rise voltage.
In fact, knowing how the Milq is designed this would be the ONLY measurement
that I would care as it ejectively demonstrate the efficiency of you LF speakers
projected to the acoustic size of you listening room. I had at my site a post where I described
the measurements I took and posted my measurements in my room. Here it is:
http://www.goodsoundclub.com/Forums/ShowPost.aspx?PageIndex=1&postID=6057#6057Rerurn to Romy the Cat's Site