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In Reply to: RE: I never use frequency counter posted by Victor Khomenko on May 11, 2024 at 15:41:23
I have a couple DSOs, one battery powered hand held (to avoid grounding shorts) and one bench DSO.
The handheld DSO also has a multimeter and signal generator (but probably not super low distortion or accuracy).
Also have an analog Tektronics scope that works great.
Just today bought the software NAK T-100 simulator but I don't have calibration tape(s) yet.
Can you recommend one available on the Bay that you think could work well with the software T-100?
I am replacing the large caps now and will be replacing the small caps on the first deck shortly. But the circuit boards are soldered to connecting wiring, not socketed, so removing and replacing is a bit more of a hassle. But I have the caps and the excellent Hakko desoldering vacuum gun so it is tedious but not that difficult.
The boards look fragile though so I will try desoldering wicks before the vacuum.
Follow Ups:
The test tape does not depend on the analysis software you use.
But it does depend on the EQ and speed - do you know what you need in that regard? Since you are in the US I presume the NAB, but then you need to know the speed.
I never tried that software, as in my office I have the Audio Precision system, and at tome I can do everything with just general tools, but I have been thinking about building a Poor Man's AP for my workshop at home.
What interface device are you using? A sound card or an external box?
Interface is Creative Soundblaster Z SE pci card. There is a newer soundblaster card with the ESS dac that ASR tested to have better specs, but the Z SE should be fine for me for now.
The T-100 simulator software can do a lot with it's own signal generator, testing frequency response, distortion, head alighnment etc.
Just need the calibration tape I guess for speed reference.
I am assuming NAB EQ for 7.5 ips tape speed. But I have not seen docs from Sony that specify.
If all goes well will be putting it all together next week, the PC is on its way too.
I have an unused bench in my basement - yes, I know, hard to believe... there is an old PC sitting there, it will be a perfect place for a test system.
When I think of an old PC, I think of the one that I have which is a Pentium 133, running Windows NT Server, and no PCI slots. ;) It still runs word processing and spreadsheets just fine. I think it has a 1200 baud modem in it.
Hopefully, yours isn't that old!
Maybe be mentally prepared to deal with compatibility/upgrade issues with your new sound card. Just fyi.
*********
We are inclusive and diverse, but dissent will not be tolerated.
It is amazing what you can buy today for $125.
but you'll be lugging decks up and down the basement to test them?
that will get old quickly...
There are no decks on the main floor (we have a single story home), it is my wife's area, except for my office there. :)
I have a 2,500 sq foot basement, part finished with a nice audio room, other finished area and then about 1,200sq foot workshop, with benches, machine tools, etc.
It is a walk-out basement, which makes moving in and out heavy professional decks possible - I use my garden tractor with a cart to bring them from the driveway over the lawn to that door, so heavy stuff doesn't have to go through the clean house portion. :)
While down there I can roll them around easily - something I often do.
I would have to add a balanced sound card, but that is not such big deal. Adds to the cost, though.
Will do. I will post my initial experience testing with the software within the next few days. Certainly there will be a learning curve for me since I have never before attempted such work with tape decks.
And I will go for a better spec'd sound card eventually, although the Z's circuitry likely far exceeds the specs of even a pro tape deck for distortion, frequency response, etc.
First testing after matching levels between deck and software.
I ran two dests, THD and Frequency response, using 7 1/2 ips, normal bias setting, Quantegy 456 tape.
THD hovered around .3% at 400hz which I believe is the only frequency the software can generate for THD test. I did not make a screen shot of that test.
The screen shot here shows frequency response sweep function plot, deck recording in forward direction, so this sums the distortion from recording through playback electronics of the deck. I do not have a calibrated tape yet so I cannot test playback seperately I guess.
Plot is about what I expected based on what I heard from listening to tapes on this unit (decent bass, rolled off highs) and prior to any recording/playback electronic work or head alighnment.
I will look at the SM and see how I can test the different recordng and playback electronics independantly to see where any problems might be. Certainly .3% distortion at 400hz would not be up to spec...
...did you get it plot two channels on the same screen?
I installed it but had problems with the sound card, doing it all in the background. The first card did not fit, even though it was supposed to. The second one had bad channel. This one is working but I only get one channel on the screen.
yes, the screen shot I posted of the plot shows two channels. I do recall in the help that if you are using a sound interface that has more than two channels in hardware there is some special configuration you may have to do of the interface.
"sums the frequency response error" would be more clear I guess than "distortion"
I ordered a PC and it should be here in a couple of days, then loading the program, and I am looking at this sound card:
I like it because it has balanced ins and outs, and the price is not bad either. Not sure about its compatibility yet.
By that time you will have gained plenty of experience, so be prepared to advise. :)
Looks like a great card for this work. The docs included with the T-100 software are quite good in my opinion.
Anyway for me the hard part is still to come: figuring out how to make adjustments and repairs to improve the performance of the Sonys so they are up to spec.
Would have been nice to still have a 909 for comparisons with the Sonys. I bet no contest...
And I am pretty sure no matter how fast I run, you will end up ahead :)
Looks like you've got your work cut out for you to get to this performance:
:)
This is a Stellavox sp7 that I used regularly, many years ago. It was custom modified by Georges Quellet and John Curl. Sure wish I could find it now!
*********
We are inclusive and diverse, but dissent will not be tolerated.
My 909 sounded so good I bet it would be close to the Stellavox. But I sold it :(
and there is a Stellavox on the bay right now for only $35K.
You should grab it :)
He was talking about the portable SP-7, not this stationary beast.
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