Re: Audio test generator and measurement - can anyone suggest a good set?


Don Black <donald_black@...>
 

I don't own a 7104. However there has been a lot of discussion here about them lately and while they are a marvelous work of art the CRT is delicate. In particular the micro Chanel wears out with use, particularly at higher intensity. If you need it's performance it's a great choice but for day to day use you'd be better off a model down (what you have should be more than enough for what you're doing).

Don Black.

On 23-Apr-13 5:10 AM, cheater00 . wrote:
 

Thanks for the tips, guys.

Here's the kind of projects I'd be interested in mostly:
- line and headphone amplifiers. Not solid-state power amplifiers
except for low-power (say 20 Watt)
- audio mixers
- tube power amplifiers, guitar amplifiers (this is the maximum
voltage I'd want to probe things at.. what's your experience - probes
safe up to 1kV should be good for that general area, right?)
- equalizers
- VCA's VCF's, VCO's for musical synthesizers
- audio compressors
- power supplies (output impedance testing, ...)

no radio or scope testing. The maximal amount of work I'd do in scope
testing would be to see if the 7704 I have still works OK after I
recap it (if I do at all). If I really needed to get a scope that can
do reliable measurements I'd probably go the whole way and import a
7104(A) - or two - from the states.

Perhaps the most ambitious projects would be a high-headroom,
low-noise DAC and headphone amplifier, or a high-headroom mastering
mixing desk with 16 channels with a useable freq range of DC to ~400
kHz.

Thanks again
Damian

On Mon, Apr 22, 2013 at 8:52 PM, David <dgminala@...> wrote:
>
>
> --- In TekScopes@..., "cheater00 ." wrote:
>>
>> Hi guys,
>> De-lurking as I've been doing some measurement equipment related shopping :)
>>
>> I'm slowly building up my workbench, and was wondering if anyone could
>> suggest what gear to get.
>>
>> After getting a Tek 7704 I now need a good sinewave generator for some
>> work. I thought to myself, why buy just a sinewave generator, when I
>> could get a distortion meter? Those have sinewave and square built in,
>> are of variable frequency, and it's better to have one large box than
>> two large boxes.
>>
>> Could someone suggest a good distortion analyzer that can be had
>> relatively inexpensively? I'm probably looking at vintage equipment at
>> this point because it can be had fairly cheaply. Something around 100
>> Euro would be a good start, but it's only a very roughly estimated
>> price range.. maybe those things can be had for much less -- or only
>> for much more? Note - doesn't necessarily have to be tektronix...
>> although I'll be perfectly happy if it is.
>>
>> Also: are distortion analyzers always limited to 20 Hz - 20 kHz, or
>> are there not-too-unusual ones that go below 1Hz and high above?
>>
>> What is the 'workhorse' distortion analyzer? Is there one or a few
>> that were very good and very popular? It's important to me not to buy
>> something relatively unknown, so that when it breaks I can find
>> replacements, schematics, and people who know how to repair them.
>>
>> What other tools - other than a distortion analyzer - could I see
>> myself using when building filters, mixers, amplifiers, etc? In the
>> future I'd also like to work a bit on tube circuits, but this is not
>> currently a major focus.
>>
>> My plan is to get a distortion analyser (with integrated square and
>> sine wave oscillators), and I already have a frequency counter for the
>> Tek 7000 coming in. I'd probably get a curve tracer at some point too,
>> and maybe a precision current and voltage source or precision
>> amplifier. Still need an esr/LC meter, I saw some boxes online. To
>> round this off I'd probably get an isolation transformer and possibly
>> variac (or both in one box). Currently not planning for a tube tester
>> or for anything that can measure transformers. Am I missing something
>> as far as the most basic measurement equipment goes?
>>
>> Thanks,
>> D.
>>
>
>
> I've not heard of a distortion analyzer that contains a square wave generator, however, the HP 339A will certainly handle the oscillator and distortion analysis criteria. The frequency range is 10Hz to 110Hz for both functions.
> The HP 334A has a wider frequency range (5Hz to 600KHz, and also has an AM detector to allow distortion analysis on AM signals), but contains no oscillator output.
> Both are frequently available on eBay.
>
> You might investigate the Tektronix TM500 series of modular equipment. The series contains oscillators, function generators, scopes, counters, pulse generators, etc. The modules plug into a mainframe/power supply. This flexibility means that you can build an instrument containing all the instruments that you need for frequency response, distortion, etc., into a single package. If your aim is for scope repair and calibration, you can assemble all the needed equipment into a single package, interchanging the modules as you wish.
> Most are on eBay frequently. These modules are somewhat more costly than conventionally packaged bench test equipment, but their small size and interchangeability are great benefits.
>
> All that said, the equipemnt that you should target is highly dependent on the type of equipment that you will be servicing. Give us an example of the types and quality of the equipment to be serviced and we can offer more pertinent suggestions.
>
> Cheers,
> Dave M
>
>
>
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