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I’m going to build a switch/outlet power box to turn my Harmon-Kardon audio amplifier on/off. I have been using the switched output of my receiver. My question is: Is there a simple circuit to ramp up the 120 v ac ? My thinking is that might be easier on the KT-88 tubes in the amplifier. Or is it unnecessary?
Skip Magnuson W7WGM
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I was going to try to make something similar, but was going to try these power tool adapters for dust?control. What they are is basically a current sense that will trigger a relay as long as a load is on the primary outlet. Some have high and low sense and possibly. I thing they trigger at 2amps.
My plan was to use it for audio amp and other accessories once I turn on the ham radio(s).
Look on Amazon for automatic dust control relay or automatic vacuum switch.
If your Kt88 amp has a tube rectifier they generally have a nice ramp up. 5U4GB are nice and slow, some are fast but still take some time. I have built a few kt88, 5881, 6L6, 6V6 amps and use them daily.?
Sandy WN6CTY
I’m going to build a switch/outlet power box to turn my Harmon-Kardon audio amplifier on/off. I have been using the switched output of my receiver. My question is: Is there a simple circuit to ramp up the 120 v ac ? My thinking is that might be easier on the KT-88 tubes in the amplifier. Or is it unnecessary?
Skip Magnuson W7WGM
|
eBay item #?404481804963, under $10 Jim Logic: Method used to arrive at the wrong conclusion, with confidence.? Murphy
I was going to try to make something similar, but was going to try these power tool adapters for dust?control. What they are is basically a current sense that will trigger a relay as long as a load is on the primary outlet. Some have high and low sense and possibly. I thing they trigger at 2amps.
My plan was to use it for audio amp and other accessories once I turn on the ham radio(s).
Look on Amazon for automatic dust control relay or automatic vacuum switch.
If your Kt88 amp has a tube rectifier they generally have a nice ramp up. 5U4GB are nice and slow, some are fast but still take some time. I have built a few kt88, 5881, 6L6, 6V6 amps and use them daily.?
Sandy WN6CTY
I’m going to build a switch/outlet power box to turn my Harmon-Kardon audio amplifier on/off. I have been using the switched output of my receiver. My question is: Is there a simple circuit to ramp up the 120 v ac ? My thinking is that might be easier on the KT-88 tubes in the amplifier. Or is it unnecessary?
Skip Magnuson W7WGM
|
I don't know how quickly the B+ comes up in the amplifier. I had an
HK amp for years (used on a pair of RCA theater speakers). The KT88/5881
is designed for the Ultra-Linear circuit where the screens are run at
plate voltage. It has enough screen dissipation to survive that plus is
designed to have low IM distortion. Unfortunately, I had to sell the
whole rig.
A remote switch will certainly be easier on the line switch in the
pre-amp.
I miss high end audio but am almost deaf now.
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On 11/30/2024 4:29 PM, Waldo Magnuson via groups.io wrote: I’m going to build a switch/outlet power box to turn my Harmon-Kardon
audio amplifier on/off. I have been using the switched output of my
receiver. My question is: Is there a simple circuit to ramp up the 120 v
ac ? My thinking is that might be easier on the KT-88 tubes in the
amplifier. Or is it unnecessary?
Skip Magnuson W7WGM
--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998
|
MFJ has a step start. They make one for 120 and 240 volts. The manuals with schematics are on line. Bob W4JFA?
On Sun, Dec 1, 2024, 2:27 AM Richard Knoppow via <1oldlens1= [email protected]> wrote: I don't know how quickly the B+ comes up in the amplifier. I had an
HK amp for years (used on a pair of RCA theater speakers). The KT88/5881
is designed for the Ultra-Linear circuit where the screens are run at
plate voltage. It has enough screen dissipation to survive that plus is
designed to have low IM distortion. Unfortunately, I had to sell the
whole rig.
A remote switch will certainly be easier on the line switch in the
pre-amp.
I miss high end audio but am almost deaf now.
On 11/30/2024 4:29 PM, Waldo Magnuson via wrote:
I’m going to build a switch/outlet power box to turn my Harmon-Kardon
audio amplifier on/off. I have been using the switched output of my
receiver. My question is: Is there a simple circuit to ramp up the 120 v
ac ? My thinking is that might be easier on the KT-88 tubes in the
amplifier. Or is it unnecessary?
Skip Magnuson W7WGM
--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998
|
MFJ part # is mfj-icp-120 or Mfj-icp-240. Bob W4JFA?
MFJ has a step start. They make one for 120 and 240 volts. The manuals with schematics are on line. Bob W4JFA?
On Sun, Dec 1, 2024, 2:27 AM Richard Knoppow via <1oldlens1= [email protected]> wrote: I don't know how quickly the B+ comes up in the amplifier. I had an
HK amp for years (used on a pair of RCA theater speakers). The KT88/5881
is designed for the Ultra-Linear circuit where the screens are run at
plate voltage. It has enough screen dissipation to survive that plus is
designed to have low IM distortion. Unfortunately, I had to sell the
whole rig.
A remote switch will certainly be easier on the line switch in the
pre-amp.
I miss high end audio but am almost deaf now.
On 11/30/2024 4:29 PM, Waldo Magnuson via wrote:
I’m going to build a switch/outlet power box to turn my Harmon-Kardon
audio amplifier on/off. I have been using the switched output of my
receiver. My question is: Is there a simple circuit to ramp up the 120 v
ac ? My thinking is that might be easier on the KT-88 tubes in the
amplifier. Or is it unnecessary?
Skip Magnuson W7WGM
--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998
|
Hi Richard, ? Just curious: was your HK amp a Citation II model ? ? Just a remark also: this is the second time I see the 5881 tube referred as the US equivalent of the KT88, or the reverse, whatever… The US “equivalent” of the KT88 is the 6550 (Tung-Sol produced and marketed those first). The KT88 from the General Electric Co. of England came after as a “replacement” of the 6550. But the ORIGINAL KT88 is very different from the 6550 and does not “sound” the same, despite having the same specifications. ? The 5881 (from Tung-Sol, again) is a variant of the 6L6 and was sometimes used as a KT66 substitute, despite a better choice had been a 7581A. ? 73, Jacques, VE2JFE in Montreal
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You are right and my memory is bad. It is the KT-66 that is the
equivalent to the 5881. The 6550 is the KT88. Both tubes are intended
for Ultra-Linear or McIntosh amps where the screens must have increased
dissipation and are designed to have low IM.
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On 12/1/2024 9:12 AM, Jacques_VE2JFE via groups.io wrote: Hi Richard,
Just curious: was your HK amp a Citation II model ?
Just a remark also: this is the second time I see the 5881 tube referred
as the US equivalent of the KT88, or the reverse, whatever…
The US “equivalent” of the KT88 is the 6550 (Tung-Sol produced and
marketed those first).
The KT88 from the General Electric Co. of England came after as a
“replacement” of the 6550.
But the ORIGINAL KT88 is very different from the 6550 and does not
“sound” the same, despite having the same specifications.
The 5881 (from Tung-Sol, again) is a variant of the 6L6 and was
sometimes used as a KT66 substitute, despite a better choice had been a
7581A.
*73, Jacques, VE2JFE in Montreal*
--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998
|
Its been a while but I believe it was a Citation II. Also had
several Dynakit 50 Watt amps. Had to get rid of them all.
I miss the theater speakers. They were c.1936 RCA Shearer horns
from a movie studio with M-G-M spec HF drivers. I built cross-over
networks for them. Fields ran off 12 V. battery chargers. They were
probably not very high fidelity but they had a very distinct presence
and very clean low end. At the time my ears still worked well, no more.
The HF drivers were built by Lansing and had aluminum diaphragms in
place of the phenolic ones used in RCA's standard theater speakers. I am
pretty sure the woofers were made by Jensen but am not sure, RCA might
have made them. I measured the mechanical and acoustical characterists
and found they were right for the horns. I am pretty sure these speakers
were at least inpired by the experimental two way horns developed by
Bell Labs for their stereo experiments, but very much simpler. Western
Electric and Lansing built similar horns. Too OT, will quit.
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On 12/1/2024 9:12 AM, Jacques_VE2JFE via groups.io wrote: Hi Richard,
Just curious: was your HK amp a Citation II model ?
Just a remark also: this is the second time I see the 5881 tube referred
as the US equivalent of the KT88, or the reverse, whatever…
The US “equivalent” of the KT88 is the 6550 (Tung-Sol produced and
marketed those first).
The KT88 from the General Electric Co. of England came after as a
“replacement” of the 6550.
But the ORIGINAL KT88 is very different from the 6550 and does not
“sound” the same, despite having the same specifications.
The 5881 (from Tung-Sol, again) is a variant of the 6L6 and was
sometimes used as a KT66 substitute, despite a better choice had been a
7581A.
*73, Jacques, VE2JFE in Montreal*
--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998
|
Hi Richard, A Citation II ! This is a special amplifier: video pentodes used as input + drivers, with multiple feedback loops. I have one that waits to be “restored”. See attached. ? 73, Jacques, VE2JFE in Montreal
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Citation 2--- That’s a monster with a ton of iron! ..now that I see one ?
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From: [email protected] [mailto:[email protected]] On Behalf Of Jacques_VE2JFE via groups.io
Sent: Sunday, December 1, 2024 3:52 PM
To: [email protected]
Subject: Re: [HallicraftersRadios] Non-Hallicrafters question (audio amp)? Hi Richard, A Citation II ! This is a special amplifier: video pentodes used as input + drivers, with multiple feedback loops. I have one that waits to be “restored”. See attached. ? 73, Jacques, VE2JFE in Montreal -- don??? va3drl
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-------- Original message -------- From: don Root <drootofallevil@...> Date: 12/1/24 1:48 PM (GMT-08:00) Subject: Re: [HallicraftersRadios] Non-Hallicrafters question (audio amp)
Citation 2--- That’s a monster with a ton of iron! ..now that I see one ? ? Hi Richard, A Citation II ! This is a special amplifier: video pentodes used as input + drivers, with multiple feedback loops. I have one that waits to be “restored”. See attached. ? 73, Jacques, VE2JFE in Montreal -- don??? va3drl
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we are in the wrong group but?
i own an A300 that uses 7408/6v6 output. simple amp w/a great sound w/only 12 watts out.
???????????? barry
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That's the one
-------- Original message --------
From: don Root <drootofallevil@...>
Date: 12/1/24 1:48 PM (GMT-08:00)
Subject: Re: [HallicraftersRadios] Non-Hallicrafters question (audio amp)
Citation 2--- That’s a monster with a ton of iron! ..now that I see one
?
?
Hi Richard,
A Citation II !
This is a special amplifier: video pentodes used as input + drivers, with multiple feedback loops.
I have one that waits to be “restored”.
See attached.
?
73, Jacques, VE2JFE in Montreal
--
don??? va3drl
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Jim Whartenby
Bob
Jacques_VE2JFE
don Root