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tube fanatic

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Posts posted by tube fanatic

  1. A fix which "may" work is to remove the buttons from the switch shafts, stand the receiver up vertically on its back, and let some Deoxit (using the bottle version with the long tube attached) run down the shafts into the switch housings. Doing that, and working the switches multiple times, may restore operation. Certainly worth a try.

  2. Keep in mind that every piece of electronics which you add to the signal path has the potential to introduce degrading factors such as noise. Also, the additional interconnects needed can have a sonic influence as well. I've always favored dealing with room acoustics with mechanical means whenever possible; and since you are going to rely on your ears to make the changes, that may be a better and more cost effective way of dealing with the acoustics.

  3. Go to ebay, vintage electronics, type in "handmade tube amplifier" you will see a really nice amp I have up for sale. Its worth your trouble.

    You are certainly correct about not being able to buy the parts to build an amp like this for your asking price! Why are you "giving it away" for so little???

  4. Hey Gregg! My wife has used one of the Gold's Gym recumbent bikes for a number of years (I didn't check the model as it's probably discontinued by now). We got it on sale at Walmart and it wasn't too expensive as I recall. She's 6 feet tall and doesn't have the frame extended to nearly what it's capable of (I'm your height and can easily use it too; but I prefer walking). Pedal tension can be selected, and at the highest level the effort is significant. The seat isn't overly padded, but an additional cushion can always be used. Lumbar support isn't wonderful though, and isn't adjustable on this model, so if you have stenosis it may get a bit uncomfortable without that capability. Hope this info helps. Regards- Maynard

  5. Unplug it, open it up, and take a look at the wires to the input jack (assuming that it isn't circuit board mounted). The problem "may" be there, although there is much else that could cause the symptom you describe.

    Anything in particular I am looking for with the wires? Solid connection?

    Yes, look for a solid connection to the center pin of the jack in
    particular. If you have an old, crappy, speaker you can connect it to,
    power it up (being extremely careful not to touch any exposed 120 volt
    wiring from the power cord), and use a straw or piece of dowel to move
    some of the leads around to see if you hear anything in the speaker. In
    fact, if you can feed a signal into the amp from a tuner or cd player,
    you can use this method to determine if moving any wiring results in
    sound being heard.
  6. Looks like two of the 6CA7s have lost their vacuum. Replace those before powering up!

    Thanks for the advice!!! I think I will have a tube tech rework the pre and amp before I turn it on!

    Definitely a good idea. Lots of capacitors need to be replaced before you put it into regular use. It's a great amp, with lots of power, so I'm sure you will enjoy it tremendously! Post or email if you need any info or advice........

  7. I would like to try one that is clean, to go after my tube pre, a JMA Merlin, feeding a lower input impedance SS amp. I lose too much bass going from the higher output impedance of the Merlin into a lower input z on the SS amp.

    I noticed most of these buffers use lower voltages, i.e., starved plate, starved heaters, etc., which are normally used for guitar effects.

    Bruce

    Since you're interested in starved circuit applications, you may find this article informative:

    http://www.freewebs.com/valvewizard2/Triodes_at_low_voltages_Blencowe.pdf

  8. Thanks for the input .I am researching the concept of the buffer.I have made no final decision and may not even experiment with it.If I do try it I would like to use quality parts and a known design.If I do not like it I could probably sell it for the investment to someone.How about some designs with arguements for or against a design.Thanks.K.C.

    There are all kinds of designs which have been used for vacuum tube buffers. However, as Erik pointed out, everything that is introduced into the signal chain has the potential to degrade, not improve the sound. Back in the 80s, passive line stages were quite popular because many believed that every component, solder joint, plug, jack, etc. in the signal path has the potential to decrease sound quality. And there is merit to that belief. If you build/use a buffer you will be introducing additional power supply hum (even with the stiffest designs, if AC operated, there will be some degree of ripple which is passed through), tube noise, microphonics to some degree, and so on. Then there's the issue of an additional set of interconnects which can possibly alter the resultant sound. Given how high the input impedance of your preamp is, there is really no need to bother with a buffer, as I mentioned previously. Your best bet is to find someone who can bring one over, or loan you one, so you can try it without spending any money. I seriously doubt that you will find that it improves the sound at all!

  9. The CD player has as output impedence of 470k ohms and the preamp an input impedence of 47k ohms.I want to keep the Denon 5600 preamp and amp because they are (to my ear) exceptional audio equipment.I have been looking over Glasswares offerings and TubeCad's interpretations of these buffers.Joe's descriptions of these buffer designs are very insightful.K.C.

    There's no way that the CD player output impedance can be that high! Typically, the values are a few hundred ohms. Even if the output impedance of the CD player is very high, say 1k, there is not going to be any interface problem when driving the 47k load at the preamp's input.

  10. It seems strange that the same problem is affecting both speakers. Are the shorting straps between the upper and lower speaker terminals still there? If the straps are there, try removing them and connecting one set of terminals at a time to your receiver (keep the volume low) to verify that only the tweeters are working. Although unlikely, it's possible that the woofers have gotten disconnected from possible rough handling during the move. If that's the case it should be an easy matter for you to remove the speaker panels and simply reconnect them.

  11. On the flip side I realized that I now need to come up with an amp for them. I'm thinking one of those cheapo t-amps.

    At 85 dB sensitivity, I'd think you'd need more than a T-amp.

    The impedance stays above 6 ohms across the entire audio band- they should be easy to drive with a low power tube amp, T-amp, etc.

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