Audio Systems/Amp continuity


QUESTION: I purchased two milbert tube has continuity from the gold RCA connector to the rest of the system.the other one does not.which amp is wrong an why?

ANSWER: I am not clear on what you mean by continuity from the rca to the rest of the system.  Are you talking about signal tracing or resistance readings?

In any event, if an amplifier is not working properly it should be pulled from the system and bench tested, diagnosed and repaired.  Tube amps are generally easy to troubleshoot so long as you have basic tube amplifier expertise.  Also, I think the Milbert factory is still in business and could provide support for your model.

Let me know if you have further questions.

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QUESTION: the amps haven't been installed all im using is a voltmeter.with a buzzer to indicate continuity.
milbert told me just to hook it up to see if it works.well it getting hook to a digital alpine with PXI-H9901 preamp,6 other amps,2 subs an multiple tweeters an would a big hassle to test one amp.almost impossible to compare to the other.
when I said continuity to rest of system.i meant the rest of amp (the circuit board,housing,etc.)
is there a way to test it without connecting it to system?
I would think one having full continuity an one having no continuity.would be a bit of a concern.  thanks

ANSWER: I am still at wonder what you mean by continuity.  Continuity in electronics usually refers to a resistance measurement.  Resistance is a passive test and mostly the component under test must be removed from its circuit to avoid parallel paths that will adversely effect the readings.

As before, to troubleshoot an amp it is best done by pulling  it out of the system and bench testing it.  This requires some sort of input signal, proper power to the device under test and an output device such as a speaker or oscilloscope or something to tell if the output is what you are expecting.  The input signal can be from a sine wave generator or cd player or fm tuner or some kind of program source.  If there is no appropriate output signal then the amp is on the bench so it can be diagnosed with signal tracing and voltage checks.

If you need more, let me know but I must learn from you which amplifier you have by model number....  Otherwise we are stabbing in the dark at each other!

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QUESTION: When building a speaker do you determine how much cotton to put into the box?

The box design (closed or vented; air suspension or bass reflex) is nice to know. Also, the size of the box and thickness of the wood panels all have some effect.

Theoretically, it goes something like this:  The inner stuffing (cotton or fiber glass or whatever) creates a longer path for the sound to travel by virtue of the fibers that the sound has to work around as it travels to one of the walls.  So, the purpose it to help match the resonance of the system and create an effective larger box than without the stuffing. But, if you completely stuff the box then you lose a lot of acoustic power as the reflective waves get absorbed by the stuffing material.

The above discussion will shed some light on your question.

My advice is ONE: if the box is real solid and sturdy and no loose objects inside or particles that will come off during sub mode then why add an stuffing at all; TWO: if the tuning of your box needs just a little bit bigger size then adding either dacron or fiberglass will make look a little bit bigger than it really is; THREE: I don't know about cotton but you can experiment with it.  In the long run most professionals and experienced amateurs do it by experimentation; FOUR:  If the box walls are not so thick and sturdy and you can feel the walls vibrating while the sub is thumping away then you could add a 3 or 4 inch batten of insulation of some kind.  However, don't expect any really big difference; we are talking about subtle changes when it comes to sub design.

Hope this helps.

PS:  Crossover frequency may be a factor. If you are crossing over above 150 or 200 hz you may want insulation to damp down reflections inside the box for the benefit of the higher frequencies that would be rattling around inside the enclosure.

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Audio Design Engineer; systems, loudspeakers, cd/dvd players, etc. I am knowledgeable in all high end audio equipment and installations. MAKE SURE YOU GIVE A MAKE AND MODEL NUMBER AND CAR IF IT IS AN AUTO QUESTION. Note: I am getting some who ask good questions that take a lot of time to research but then the questioner fails to read the answer. Please don't ask questions unless you are seriously looking for an answer. If you find an answer to your question otherwise then let me know with your reply. Thank you.


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