Curve Tracer or Audio Analyser?

benc

Member
2010-04-04 10:23 pm
Ipswich
I'm now a full-time instrument maker, and thinking about how I allocate resources in 2020. I've been into DIY hifi since a teenager and want to resurrect two pet projects (1. Curve Tracer and 2. Audio Analyser) for my little company (Electron Plus) - thinking about which might have the most impact. Would love to hear feedback, what people are using and perhaps what's on their wishlist. The very basic specs as I left them before I got busy with sub-contract work:

Curve Tracer
PC connected
-200 to +200V collector supply
-20 to +20V / -200mA to +200mA step generator
<1uA to >5A
Dual channel option/version
2nd step generator/SMU option/version.

Audio Analyser
2channels
Fully floating input and fully floating output sections
>+20dBV outputs
Balanced ins and outs
48/96/192 and possibly 768KHz rates

I built working prototypes of both a few years back - but would probably refresh both designs (certainly restart the digital side of things). Probably got enough resource to do one of these projects only.
 
Hi,

I'd opt for a curve tracer since there's almost nothing around.
With countless soundcards and tons of free software, as well as very good affordable audio analyzers on the market another audio analyzer seems to make not much sense.
Curve tracers on the other hand are a rare breed. Those few existing projects restrict to rather low voltage and current ranges.
There's almost nothing that can do power transistor characterization.
Personally I would like to see something like a modernized Tek 576, with PC control and a modular concept which allows for scaling up voltage and current levels.

jauu
Calvin
 

benc

Member
2010-04-04 10:23 pm
Ipswich
Thanks Calvin for the comments.
There certainly seems to be more AA's available than when I last looked, and the CT is closer to production. Tek's 576 and 370 have been on my watchlist for long time. What would you say is the upper limit on useful voltage and current. Is 200V/5A enough?
 

Jazid

Member
2009-12-15 7:02 pm
If you can get the tracer to cover valve ranges as well then that would extend your customer base. Of course that would require heater supplies and screen voltages as well but an 'all in one' tracer would be an asset on many a DIYers bench. If you visit the tube testers forum there's a chap there (Dennis) who has made a pcb to convert 576 tracers to test valves and can offer amazing info.

I agree that an audio analyser is possibly a common enough tool that you'd be pushed to offer anything either good enough or cheap enough to compete with existing products. Look at the RTX project, all the goodwill and effort it could garner, but it went out of production promptly [emoji22]
 

thermionic

Member
2004-01-11 11:01 pm
UK
If you are in the market for a CT, then by default you are probably not averse to DIY-ing your own. If you do some research I suspect you might find there to be a surprising amount of kits out there. They may not all be supported / in production, though. My feeling is that an AA is less likely to be in competition with diy kits and other small OEMs. As an owner of 4 AAs, I feel they all have some drawback or other. I don't understand why in 2019 there isn't something as convenient as a DScope, but with THD+N spec to rival the UPV or 2722. I would buy that (assuming the SW isn't clunky - which it is in the case of most AAs).
 

benc

Member
2010-04-04 10:23 pm
Ipswich
Thanks Thermionic for the comments. I've spent time with both the UPV, DScope3, 8903 and used to own an Amber 4400 - still own a few others (W&G SPM11/SPMZ110, Ferrograph, various HP). Speed of use and ease of setup is really important to me - I dread having to learn yet another interface and even returning to a piece of gear that I haven't used for a few months can be daunting. Affordability will be the biggest challenge; may need to make more than one model in-order to cover several different 'industries' and price points - that said I might be able to fuse the CT project with another project here and that would help alot in justifying the expense.
 
Curve tracing is not difficult, and hardly demands better accuracy than 0.1%.
(Yes we built our own for low voltage FETs.)
Analyser plus functions generator to -140dB is another story.
Commercial users can afford to buy an UPV or 2722, or the like.
Not most hobbists.

That said, it depends on how affordable.
Also not so easy to beat the likes of an RTX on price and performance.
RTX6001 Audio Analyzer with Multi-Instrument Full Package | Virtins Technology


Cheers,
Patrick
 
I don't understand why in 2019 there isn't something as convenient as a DScope, but with THD+N spec to rival the UPV or 2722. I would buy that (assuming the SW isn't clunky - which it is in the case of most AAs).

There is one. It's called an APx555B and is yours for a mere $30k.
Like they say: if it was so easy, everybody would do it and certainly would not be $30k!

I never had the need for a CT. Why would you want to curve trace individual parts? A data sheet gives you all the info and, more to the point, gives you min and max values for not just one part but the whole family.
Probably because I would never design anything that needs selection and/or matching of parts.
But I may be missing something.

Jan
 

benc

Member
2010-04-04 10:23 pm
Ipswich
Thanks all so far:
It's looking like there maybe a few of options that i'll have to slim down:
a. 3 terminal version, 200+V, 1-2A, 4 different 'collector' resistors.
b. 5 terminal version, 400+V, 5-20A (C/E sense terminals), 8 different 'collector' resistors
c. 10 terminal version of 'b' (with relays to change over terminals)
d. As above with heater drive, 2nd (screen) supply and higher voltage step generators.

'a' would be a cost reduced unit.
'b' version is the closest to what I built before
'c' might be better to produce/more popular than 'b'
'd' would be a 'tube&solid-state' edition

Will consider making a unit upgradable by adding a module/modules, but this would require a front panel with blanking plugs or supplying a new front panel - both possibilities straightforward.
 
AP uses a number of blank front panel subpanels that are replaced with new options.

Jan
 

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benc

Member
2010-04-04 10:23 pm
Ipswich
AP uses a number of blank front panel subpanels that are replaced with new options.

Jan
It's a nice idea. But this probably won't be physically big enough for that to make sense. Also sanity checking to see if we should modularise some of the bits inside (the enclosure at the moment is around 230x175x60mm), even if just for serviceability - keeping a keen eye on the Bill-Of-Materials here.

For those into tubes/valves, any idea what the maximum Grid voltage required will be; -50V enough? more? Also seeing on the bench of it is possible to stack the collector supplies (these are fully floating, we make our own transformers) to get to 800V under certain conditions, although this might cause a headache in layout.
 

benc

Member
2010-04-04 10:23 pm
Ipswich
I have a DCA75, it is limited to +/-10V @ perhaps 10mA. Very limited for curve tracing apart from some special cases. Our ASA100/CPA100 (Electron Plus) will give you an idea of how we price things and how carefully we design - definitely keeping an eye on the BOM - and that's probably why we will have several versions of a curve tracer.

I'm basing the step-generator on the design of a 2 channel SMU that we designed here - http://youtu.be/KkDIATgGuxI
 
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Jazid

Member
2009-12-15 7:02 pm
Negative grid down as far as you can manage...Although the majority of audio tubes seem to need modest grid volts, 300b like - 75V at average operating conditions, and transmitting valves can take some *different* conditions. So saying - 120V sounds good?
I guess for us tinkering DIYers there's also a joy in old valves, and these can definitely use a tracer. Even identifying some 1920s/1930s valves might be easier with a tracer! For me at least [emoji16]
 
There is one. It's called an APx555B and is yours for a mere $30k.
Like they say: if it was so easy, everybody would do it and certainly would not be $30k!

Jan

There is a thread at EEVBlog where someone did a tear down on a UPV. I fully realise that the analogue circuitry is the toughest aspect in designing an AA, but it is 19 years since the 2722 was released.... Whilst an AA isn't subject to Moore's Law as acutely as a purely digital device, 19 years is a long time in electronics. It would seem that Aver Labs have nearly got what I'm describing. I am sure that, given the R+D budget, an AA with performance somewhere around the 2722 could be achieved, but with a footprint similar to a DScope and price akin to an RTX.