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Greater Toronto Area DIY meetup
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Old 16th October 2020, 10:02 PM   #1411
Mikett is offline Mikett  Canada
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Location: Toronto
Quote:
Originally Posted by mhenschel View Post
@mikett Thanks.

That's a technique reminiscent of one I read in a TAA letter about making pseudo litz cables by twisting. A lot of work to get a tighter twist!

Is the objective to get more turns per inch or to keep the wires close together along their length... or both?

Insulation thickness might be consideration in either case.
For me it makes the wires more manageable and I don't have to go out and purchase more cables actually. Yes, they say that it makes the runs more immune to pickup. Probably true but it also neatens up a lot of things. I got the wire in the early 80s when it was discarded by someone who no longer had need for it. I've had it since and I find uses for it here and there. So it uses bespoke wire from the 80s. Wired with 40 year old stock copper that has been carefully aged like vintage wine.

Last edited by Mikett; 16th October 2020 at 10:06 PM.
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Old 17th October 2020, 03:04 AM   #1412
Lo_Tse is offline Lo_Tse  Canada
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Originally Posted by Mikett View Post
I looked at a twisted pear when I burned out my first DAC board. ( My hand slipped with a probe and AVCC got 12V instaed of 3.3V) and instant smoke, CMOS construction)

Then I started to add up what a Twisted Pear would cost in the end when I would finish and it was not too far off what a Benchmark DAC3 would run and with the Benchmark, the resale value is very high. Whereas with DIY stuff, not that much. So my theory at the time was that the taxes on the Benchmark = cost of DIY DAC or so I thought. Was not to be the case.

The other thing is the amount of work for the chassis in the case. I needed a ready made case and I was able to obtain a DAC case premachined as well as the identical case with no machining for the power supplies. That was a significant factor for me.
Mike,

Looked like you have been real busy. You have to bring your new toys to the next meet.

After going through the reviews of some of those small commercially available DACs came out of China at AudioSciencereview.com, I decided that there is really no point for me to even try to assemble a DAC. For a few hundred dollars, the performance one can get is amazing. Everything is properly done (PCB layout, multiple stages of ultra low noise regulated power supplies, top of the line ESS DAC chip, CNC milled aluminum case etc.) and many of them come with a headphone amp and can be used as a preamp.

I am planning to build a pair of small full range speakers (5" driver) from a kit. Unfortunately, the COVID-19 situation is really impeding the transportation of all the parts needed, which are actually sitting in HK waiting for me to pick up. The original plan was that I would fly back for vacation and bring them with me when I return. With the pandemic, don't know when can I take the trip. Shipping is expensive and I rather used the money to cover part of the plane ticket cost. Hopefully, I can bring the speakers to show you folks in the next meet (sometime next year I hope).

Regards,
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Old 17th October 2020, 03:58 AM   #1413
BigE is offline BigE  Canada
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I can't wait to see what everyone has been building!

I promise to bring my F5T, so long as I can get some help lifting it out of the trunk. It lives on a wheeled cart now.....

I've also modified the DCB1 buffer some of you may have already heard..... it's got an XLR input courtesy of a neurochrome buffer board instead of the plain single ended one. That board is totally transparent as far as I can tell...

And it may be using the ALLO stepped volume control ( I hope it works well ) -- or a DACT/Khozmo if it does not. The Allo should arrive in a week or so.

Also, with luck, the AKSA lender preamp will be built, which can push 40 V -- that is in preparation for an F4 build.

Have any of you compared the DACT with the Khozmo Ladder?
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Old 18th October 2020, 02:38 PM   #1414
Mikett is offline Mikett  Canada
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Originally Posted by Lo_Tse View Post
Mike,

For a few hundred dollars, the performance one can get is amazing. Everything is properly done (PCB layout, multiple stages of ultra low noise regulated power supplies, top of the line ESS DAC chip, CNC milled aluminum case etc.) and many of them come with a headphone amp and can be used as a preamp.

Regards,
Absolutely correct! I was only half way through building the DAC and there was always more work to do. I got frustrated and decided to shelve everything and ordered what was possibly exactly what you had looked at AudioScience Review.
The Topping D90. Based on specs and physically what was received, it was a no brainer, so I got one.

Then I listened to what I had "in development" and compared back and forth. I've seen comments that what measures well does not always sound good. There was a problem with female vocals on the sample of the D90 relative to what I had in development. I was not totally satisfied. It clearly was better than what I had in development and by all accounts very good but the problem with female vocals especially voices like Stacey Kent was bothersome. That put a fire on my rear to finish the DAC I was halfway through for about 2 years. Things took a real backward step when I burned up an expensive LTC6655 when I made a power supply and interchanged + and - on powerup. I was so pissed. I just sat on it. Then I discovered Jung's GLED and that combined with the SuperReg with the remote sense did it for me. I am still sitting on the Zetex transistor and LT6200 which has about 1/10 the noise and massive bandwidth.
Also the D90 does not convey weight of the bottom octave I discovered.

If you're not into building a tweaked machine, then something like the D90 is perfect. No Doubt. However, my belief is that something like a twisted pear and tweaked support circuits can outdo the machines like Topping BUT you're not saving money nor will it be inexpensive, you'll have lot of left over circuits and it will take a lot of time....lots of negatives. If I had not started earlier when things like the D90 was not around I probably would not have started. The days of DIY are numbered by the chinese hif products.

I am glad to hear that the Neurochrome buffer sounds good. That had been on my radar. Tom C. knows what he is doing. I really wish him well and hope his venture works out.

Last edited by Mikett; 18th October 2020 at 02:53 PM.
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Old 18th October 2020, 09:25 PM   #1415
kodabmx is offline kodabmx  Canada
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Join Date: Oct 2011
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Greater Toronto Area DIY meetup
I know this might not be the place for it, but I want to sell an amp I built, but only to local GTA people.

It's a Williamson KT88 UL design using Hammond iron including 278CX PT, 1650N OPT, 193Q choke, 155J chokes on the preamp stage, and DC for the first tube heaters. Also one touch power instead of a toggle switch.

Circuit design is 100W, OPTs are 60W. Cathode biased using Dale resistors and 22000 hour 105C caps. All caps are 105C and long life. KT88 tubes are unmarked Chinese. VA/PI is provided by 6F12P. Driver is RCA 6SN7 "Black Plate" Oooh! LMAO

Feel free to come hear it in midtown Toronto.

$1500 takes it.
I'll provide a schematic and warranty if you don't just want it for parts...

Also looking for someone interested in auditioning an RIAA stage.
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Last edited by kodabmx; 18th October 2020 at 09:28 PM.
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Old 25th October 2020, 01:17 AM   #1416
kodabmx is offline kodabmx  Canada
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Greater Toronto Area DIY meetup
I guess there's no interest?

I just prototyped some PCBs... 6F12P VA/PI, 6N8S HV driver, RIAA, active loaded pre... If someone would like a sample to build and test let me know.
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