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 Post subject: Harman Kardon TA 3000X (Tube Stereo Receiver)--Question
PostPosted: Apr Wed 22, 2020 2:48 pm 
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Hi All,

With the stay-at-home/COVID-19 concern currently taking place, I've been working from home and I've been enjoying listening to my HK TA 3000X tube receiver... Basically, running it all day long (yes, I have a cooling fan in the back of it :) ) It has 17 tubes, including four 12AX7s and four 6V6s (the tubes have been replaced within the last decade or so...)

I've noticed when I first turn it on (a cold start), one of the channels (right channel) takes approximately 5 minutes before sound comes out of the speaker. The sound is very faint at first and then the receiver warms up--all is good and no issues throughout the day. Here's my question: Is this simply a sign that one of the tubes described above are failing and the remedy is to replace the tube or is this something more complex? I guess I could swap around the tubes from one channel to the other channel, however, it's a pain to change due to the current setup of the receiver.

And now for a bonus question :D Eventually, I would like to re-tube the receiver again... Ideally, I would prefer NOS RCAs, GE, etc... but I doubt my budget would allow for this... As an alternative, are there any good quality, currently produced, recommended tubes, e.g. Electro-Harmonix perhaps? (I know this could be a very subjective viewpoint when it comes to a brand preference. I don't necessarily want the cheaply made ones... More along the lines of something of high quality at a reasonable price.)

Thanks


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 Post subject: Re: Harman Kardon TA 3000X (Tube Stereo Receiver)--Question
PostPosted: Apr Wed 22, 2020 5:46 pm 
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I like JJ's.


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 Post subject: Re: Harman Kardon TA 3000X (Tube Stereo Receiver)--Question
PostPosted: Apr Wed 22, 2020 6:53 pm 
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I have heard the NOS Russians can be good...

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 Post subject: Re: Harman Kardon TA 3000X (Tube Stereo Receiver)--Question
PostPosted: Apr Thu 23, 2020 3:34 am 
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That sounds like a weak tube, but it could be another problem. Do you have a tube tester, or access to one?

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 Post subject: Re: Harman Kardon TA 3000X (Tube Stereo Receiver)--Question
PostPosted: Apr Thu 23, 2020 12:08 pm 
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Location: Sunbury, Ohio 43074
I'd say a weak tube, or perhaps a failing capacitor. Most likely a tube. Swapping L to R channel would be the fastest test I suppose, although you'd have to wait for everything to cool down for each test unless you just swap all the tubes at the same time. Then you only have to wait once, and then knowing it is a tube, swap them back one by one.

I agree with the JJ tubes, although I'd imagine any new manufacture tube will probably be pretty good for this amp. Maybe look for NOS tubes, although you can pay a LOT for some of these on the bay these days, and while you'll get arguments all over the map on both sides of the discussion, there really is not going to be any discernible difference unless you are running near 100% output levels all day long.

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 Post subject: Re: Harman Kardon TA 3000X (Tube Stereo Receiver)--Question
PostPosted: Apr Thu 23, 2020 1:55 pm 
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Thanks everyone for some good feedback. I'm hoping it's just a tube and perhaps I'll be able to psych myself up to swap around the tubes with each channel (it's up on a shelf, etc.) Just fired it up moments ago for another workday and sure enough, it took about 5 minutes or so before the other channel came online...

I wish there was a local tube tester unit available... There used to be one in a now closed music store, if I recall correctly. (Also, remember those in Walgreen's decades ago.)

Again, thanks for the followup and the advice about the tube brands.


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 Post subject: Re: Harman Kardon TA 3000X (Tube Stereo Receiver)--Question
PostPosted: Apr Thu 23, 2020 7:12 pm 
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One more question... If it's a "tired" tube, would it be one of the pre-amp 12AX7s tubes or one of the power 6V6 tubes?

Thanks


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 Post subject: Re: Harman Kardon TA 3000X (Tube Stereo Receiver)--Question
PostPosted: Apr Thu 23, 2020 7:18 pm 
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Location: Sunbury, Ohio 43074
Guessing probably the preamp. How many 6V6 per channel? If just one, that could easily be it also

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 Post subject: Re: Harman Kardon TA 3000X (Tube Stereo Receiver)--Question
PostPosted: Apr Thu 23, 2020 7:22 pm 
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You don't need a tube tester. Substitution works just as well - better, because you can check a tube in it's actual use.

Just set the thing on a desk or bench, hook it up, and start swapping tubes one at a time. Of course you might want to give some time for tubes to cool in-between swapping, given the symptoms.

But I don't think it is a tube. It could be a tube, but it could also be a flaky cap or resistor, that depends on a certain operating temperature to start operating correctly, thus the symptoms.

It can be maddening to work on problems like that, because of the time involved, but just take a deep breathe, relax, accept that it's going to take some time, and start your testing, patiently and thoroughly.

A short cut might be to open the bottom and set it on your bench upside down, then when you first turn it on quickly check your power supply voltages. Prepare for this - if you have a schematic, familiarize yourself with all the test points and their indicated values. Make notes of the values you read on your meter. Then, after 5 minutes, check again. DO this for each tube, as needed, starting with the output.

Again, it can be frustrating - but with patience, fortitude, and a plan (and a meter) you can do it.

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 Post subject: Re: Harman Kardon TA 3000X (Tube Stereo Receiver)--Question
PostPosted: Apr Thu 23, 2020 9:03 pm 
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Thanks again for more good feedback. It has a total of 4 12AX7s and 4 6V6s.

Long term, I would like to have it recapped anyway, along with having other stuff checked out. I think it will hang in there for a while longer. I can do minimal stuff, but I get really nervous when crack open the bottom side :shock: I might try a tube swap.


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 Post subject: Re: Harman Kardon TA 3000X (Tube Stereo Receiver)--Question
PostPosted: Apr Thu 23, 2020 9:12 pm 
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Joined: Nov Wed 30, 2016 7:35 pm
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Location: Sunbury, Ohio 43074
Let the forum know where you live, approximately, and I'm sure someone can recommend someone nearby that can help you with a recap or whatever. Not every tech is as good as they think .... although some are... but recommendations are best for this. Mississippi perhaps ??k

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 Post subject: Re: Harman Kardon TA 3000X (Tube Stereo Receiver)--Question
PostPosted: Apr Fri 24, 2020 3:00 am 
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I appreciate that--I'm in the Jackson, MS area.


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 Post subject: Re: Harman Kardon TA 3000X (Tube Stereo Receiver)--Question
PostPosted: Apr Thu 30, 2020 1:52 pm 
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Just to follow up regarding the R channel issue... I was able to get a hold of slightly used 12AX7's (three) Electro-Harmonix tubes. I was able to change out 3 out of 4 that feed both channels this morning... I fired up the receiver from a cold start and all seems to work fine... No waiting for a few minutes, etc... I think it was just a bad tube. I noticed a date that I had marked on one of the tubes was from December of 2006... It probably just time to replace the tube.

As I continue to telecommute from the house (during COVID-19), I'll continue to enjoy and run the receiver throughout the day. :)


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