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Tube Radio
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Post subject: Re: Motorola SK14M HiFi Stereo Questions Posted: Jul Fri 13, 2018 11:37 am |
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Joined: Jan Thu 01, 1970 1:00 am Posts: 20412 Location: Warner Robins, GA
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Dutch Rabbit
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Post subject: Re: Motorola SK14M HiFi Stereo Questions Posted: Jul Sun 15, 2018 3:38 am |
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Joined: May Sun 13, 2012 8:12 pm Posts: 12741 Location: Central PA 16801
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i figured that would be a good value.
steve
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_________________ You have enemies ? Good. That means you've stood up for something, sometime in your life. -Churchill
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Dutch Rabbit
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Post subject: Re: Motorola SK14M HiFi Stereo Questions Posted: Aug Sat 04, 2018 2:41 pm |
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Joined: May Sun 13, 2012 8:12 pm Posts: 12741 Location: Central PA 16801
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my plan as of 10:00 this morning is to tear down the turntable and restore it, then a weekend of professional baseball down in Altoona for two days. i'll need that and a confession booth after the TT restoration  . steve
_________________ You have enemies ? Good. That means you've stood up for something, sometime in your life. -Churchill
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Tim Tress
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Post subject: Re: Motorola SK14M HiFi Stereo Questions Posted: Aug Sat 04, 2018 3:40 pm |
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Joined: Jan Thu 01, 1970 1:00 am Posts: 9358 Location: Beaver Falls, PA. USA
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The biggest limitation of a tube amplifier is the size and quality of the output transformer. Evidently, Motorola spent more money there.
_________________ Tim KA3JRT
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Dutch Rabbit
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Post subject: Re: Motorola SK14M HiFi Stereo Questions Posted: Aug Sat 04, 2018 6:16 pm |
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Joined: May Sun 13, 2012 8:12 pm Posts: 12741 Location: Central PA 16801
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they spent some money then. it sounds fantastic.
steve
_________________ You have enemies ? Good. That means you've stood up for something, sometime in your life. -Churchill
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Tube Radio
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Post subject: Re: Motorola SK14M HiFi Stereo Questions Posted: Aug Sat 04, 2018 6:37 pm |
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Joined: Jan Thu 01, 1970 1:00 am Posts: 20412 Location: Warner Robins, GA
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Tim Tress wrote: The biggest limitation of a tube amplifier is the size and quality of the output transformer. Evidently, Motorola spent more money there. They pretty much had to far as their three channel consoles go in order for the bass driver to actually produce good bass.
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Dutch Rabbit
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Post subject: Re: Motorola SK14M HiFi Stereo Questions Posted: Aug Sun 05, 2018 5:05 am |
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Joined: May Sun 13, 2012 8:12 pm Posts: 12741 Location: Central PA 16801
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turntable restoration did not go well.
someone was at it before b/c the big gear wheel that the platter turns was extremely tough to turn.
the grease froze up everywhere which caused it to not work. the double-decker idler is ground down with shards of rubber all over the top of the motor assembly.
of course, some backyard teknishiunn or should i say "makanik" took the TT apart to relubricate. the master mechanic lost springs, screws, a few other parts I think, and just bastardized the thing.
for now, I shined the turntable up and placed it back into the cabinet, where it will set until find another one, which really does not matter to me if I do or don't.
I'm using it with tuner and a soundcard input and enjoying it that way for now.
steve
_________________ You have enemies ? Good. That means you've stood up for something, sometime in your life. -Churchill
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Tube Radio
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Post subject: Re: Motorola SK14M HiFi Stereo Questions Posted: Aug Sun 05, 2018 4:59 pm |
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Joined: Jan Thu 01, 1970 1:00 am Posts: 20412 Location: Warner Robins, GA
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Artcurus
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Post subject: Re: Motorola SK14M HiFi Stereo Questions Posted: Aug Sun 05, 2018 10:50 pm |
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Joined: Feb Wed 04, 2015 12:26 am Posts: 981
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Hey DR,
If you REALLY want to talk about cooked 6BQ5, let's talk about SHERWOOD. My Sherwood S1000II that I use for my center channel has 4, runs them at about 450 per tube, and I'm lucky get 2 years out of a quad.
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Dutch Rabbit
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Post subject: Re: Motorola SK14M HiFi Stereo Questions Posted: Aug Mon 06, 2018 4:24 am |
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Joined: May Sun 13, 2012 8:12 pm Posts: 12741 Location: Central PA 16801
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yikes on those values  . did you ever calculate the static dissapation via cathode current, plate voltage, and some maths ? i'm curious to know what it may be. steve
_________________ You have enemies ? Good. That means you've stood up for something, sometime in your life. -Churchill
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Artcurus
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Post subject: Re: Motorola SK14M HiFi Stereo Questions Posted: Aug Mon 06, 2018 4:28 am |
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Joined: Feb Wed 04, 2015 12:26 am Posts: 981
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Dutch Rabbit wrote: yikes on those values  . did you ever calculate the static dissapation via cathode current, plate voltage, and some maths ? i'm curious to know what it may be. steve Plate voltage is 450. Sorry I should have put that in. Haven't tried to calculate anything else. I will tell you that amp outperforms even my DJ amps at 120 watts
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Don Cavey
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Post subject: Re: Motorola SK14M HiFi Stereo Questions Posted: Aug Mon 06, 2018 1:52 pm |
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Joined: Jan Thu 01, 1970 1:00 am Posts: 14903 Location: Fernandina Beach, FL
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Interesting reading here on the 6BQ5. If one is concerned about the high voltages or dissipation, how about using a 7189? Of course, one has to be sure that the tube socket is wired properly since the 7189A has some internal pin connections that the 6BQ5 may not.
_________________ Don
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classicelectronicsguy
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Post subject: Re: Motorola SK14M HiFi Stereo Questions Posted: Aug Mon 06, 2018 7:47 pm |
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Joined: Nov Wed 27, 2013 5:59 am Posts: 693 Location: Metzger Oregon
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Motorola used a few different turntables over the years. Could you post a picture of yours here? I have at least one spare, if I have something that'll work for you I'd be happy to send it your way for little more than the cost of shipping.
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Artcurus
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Post subject: Re: Motorola SK14M HiFi Stereo Questions Posted: Aug Tue 07, 2018 2:35 am |
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Joined: Feb Wed 04, 2015 12:26 am Posts: 981
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Don Cavey wrote: Interesting reading here on the 6BQ5. If one is concerned about the high voltages or dissipation, how about using a 7189? Of course, one has to be sure that the tube socket is wired properly since the 7189A has some internal pin connections that the 6BQ5 may not. amp originally ran 7189 but those are $$$$.
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Dutch Rabbit
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Post subject: Re: Motorola SK14M HiFi Stereo Questions Posted: Aug Tue 07, 2018 3:31 am |
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Joined: May Sun 13, 2012 8:12 pm Posts: 12741 Location: Central PA 16801
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this fisher had a pair of 6BQ5 tubes in it. it peaked 35 watts with music program, kid anyone not. these poor little tubes were like two little charred hot dogs standing up on a metal serving tray. i felt so sorry for them. here is the thread and there are pics of the tubes somewhere in it. when the project began on page 1, it certainly did NOT end as planned on page 3, but man o man, am i happy. it is a daily driver and sounds just so classic and wonderful. viewtopic.php?f=13&t=304362steve
_________________ You have enemies ? Good. That means you've stood up for something, sometime in your life. -Churchill
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Dutch Rabbit
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Post subject: Re: Motorola SK14M HiFi Stereo Questions Posted: Aug Fri 10, 2018 9:25 pm |
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Joined: May Sun 13, 2012 8:12 pm Posts: 12741 Location: Central PA 16801
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well, after using this, I have found out that the tweeter is really bright and sort of piercing. when I disconnected it and allowed the mids to just play with the woofer, the set sounded much better and not so tiring on the ears. I padded down just the tweeter in each cabinet so its amplitude is just a bit above the two mids. the set sounds even better. it is nice and crisp with detailed highs that are not at all overbearing and ear irritating. I can crank it up now without the HF bothering the eardrums so the bass just pounds. dad came down to the shop today with me. he even said that it was just too sharp and "treble-ley" as he put it. I am extremely happy. even dad is too  . I would say that the tweeter was cut down 50% from its original volume and now balances with the midrange and bass drivers. excellent steve
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_________________ You have enemies ? Good. That means you've stood up for something, sometime in your life. -Churchill
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Artcurus
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Post subject: Re: Motorola SK14M HiFi Stereo Questions Posted: Aug Sun 12, 2018 4:10 am |
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Joined: Feb Wed 04, 2015 12:26 am Posts: 981
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DR,
As a matter of fact, those JJ tubes are about the only ones my Sherwood doesn't immediately incinerate. That amp destroyed a matched pair of what was good GE oval plate 6BQ5, took about four months.
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Dutch Rabbit
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Post subject: Re: Motorola SK14M HiFi Stereo Questions Posted: Aug Sun 12, 2018 4:57 am |
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Joined: May Sun 13, 2012 8:12 pm Posts: 12741 Location: Central PA 16801
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that is good to know about the JJ.
of the very few new production tubes that i have ever used, JJ seemed to be very good.
i used a pair of 6L6gc JJs in a scott amplifier and these two pairs in this motorola amplifier.
yea, i have the good NOS and used good american tubes, but they will be in storage since the price of them are going out of sight.
notice the price of 5U4gb and the 6BQ5 tubes lately ?? holy smoke, only a few years ago, i bought 15 NOS 5U4 for a mere 20 bucks plus shipping. i also bought nice sized amazon box of used good ones at a fest for $10. about 10 years ago, i bought a pile of the soviet rugged 6n14-p/n or something like that for $20. that's not happening anymore.
steve
_________________ You have enemies ? Good. That means you've stood up for something, sometime in your life. -Churchill
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Artcurus
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Post subject: Re: Motorola SK14M HiFi Stereo Questions Posted: Aug Sun 12, 2018 11:45 am |
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Joined: Feb Wed 04, 2015 12:26 am Posts: 981
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Dutch Rabbit wrote: that is good to know about the JJ.
of the very few new production tubes that i have ever used, JJ seemed to be very good.
i used a pair of 6L6gc JJs in a scott amplifier and these two pairs in this motorola amplifier.
yea, i have the good NOS and used good american tubes, but they will be in storage since the price of them are going out of sight.
notice the price of 5U4gb and the 6BQ5 tubes lately ?? holy smoke, only a few years ago, i bought 15 NOS 5U4 for a mere 20 bucks plus shipping. i also bought nice sized amazon box of used good ones at a fest for $10. about 10 years ago, i bought a pile of the soviet rugged 6n14-p/n or something like that for $20. that's not happening anymore.
steve especially because I like to use these on my Packard Bell, (the amp is visible) https://www.ebay.com/itm/GE-5U4-GB-Vacu ... itleDesc=0
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Dutch Rabbit
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Post subject: Re: Motorola SK14M HiFi Stereo Questions Posted: Aug Thu 16, 2018 5:14 am |
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Joined: May Sun 13, 2012 8:12 pm Posts: 12741 Location: Central PA 16801
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