Yay! New toy

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Dave the bass
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#46 Re: Yay! New toy

Post by Dave the bass »

That's a good idea, incorporating a draining board into the lid, the heat from the PSU'S help with dish-drying too I'd imagine 😁👍
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#47 Re: Yay! New toy

Post by Tony Moore »

:P
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#48 Re: Yay! New toy

Post by Tony Moore »

Right, all-change - again!

After my recent experiences with the RTZ DAC and finding out how good that is, I decided to leap-frog on my currently "main" system and build yet another RTZ DAC, this time to go along with the modded Transporter.

However, with all the work I did on the TDA1541A "extensions" to the Transporter I didn't want to lose that capability.

Ray suggested that I used LVDS to export the I2S signals to a separate box to house the RTZ DAC and its power supplies. I've not used LVDS before but it seemed like a great idea to prototype since there is now absolutely no room left in the Transporter's case.

I found some ready built LVDS modules for a good price and then built a new RTZ DAC and filter board, plus another PCM2DSD "simple DSD modulator" and now have this prototyped and working on the bench. (I did have some problems with voltage levels and blew up the FPGA on the DSD converter board but we won't talk about that! :oops: )

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I have just about worked out the layout for the inside of this separate case:

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Which will be something like this:

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Connection between the Transporter and the new case will be a short HDMI lead.

This will enable me to use the Transporter as streamer or take input from other digital sources and output either via the TDA1541A outputs or via the RTZ DAC outputs and if nothing else should be an interesting comparison at any future meet-ups.

Watch this space for more build pictures as I progress! :roll:
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#49 Re: Yay! New toy

Post by Tony Moore »

OK, I have now assembled the "simplified" version of the filter board, as created by Ray and powered up.

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This simplification removes the final high pass filter stage with its coupling caps. With very little DC offset I am hopeful that this will not cause any degradation of the Lundahl output transformers since they do have a huge overhead anyway.

Initial tests are favourable! I will do a proper A/B comparison once I have the power supplies built.
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#50 Re: Yay! New toy

Post by Tony Moore »

Very little progress on the casing so far. I _have_ been slowly making the 3d printed sub-structures to help with the fitting.

This is a test fit to ensure that my drilling templates (the thin blue 3 printed parts) are correct. It seemed easier to make some templates and then drill/file up to them, rather than just trying to scribe on the panel as it is awkward, having the channels already fixed to it, plus the coating is hard.

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Nothing is yet marked out for drilling so room to adjust the position and spacing of the main modules a little.
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#51 Re: Yay! New toy

Post by Tony Moore »

OK, almost completed now!

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And the two RTZ DACs / Streamers together:

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I still have to do some panel-work on the transporter to fit the LVDS module to the back panel. Plus I think I'll add a switch to turn off mains to the TDA1541A parts that I built into the Transporter so that when I don't need to use that I can save power and heat.
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#52 Re: Yay! New toy

Post by Tony Moore »

And now full cicrle:

LVDS module installed and hooked up to the I2S from the Transporter after being converted from Left Justified. The Transporter is now capable of outputting from the TDA1541A for the classic sound or can be connected to the outboard DAC for DSD reproduction.

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Further developments are all concentrated on the output filter stages of the RTZ DAC. I am currently listening with a passive filter built around simple capacitor DC blocking and Lundalh LL1588 transformers and it is sounding fantastic. Next step is to try separate +/-15v supplies for the active filter board and see how that compares.
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#53 Re: Yay! New toy

Post by Ant »

Lovely neat job tony!
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Greg
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#54 Re: Yay! New toy

Post by Greg »

Very nice, Tony. Are you bringing it to Owston?
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#55 Re: Yay! New toy

Post by Tony Moore »

Ant wrote: Tue Aug 22, 2023 12:34 pm Lovely neat job tony!
Greg wrote: Tue Aug 22, 2023 4:51 pm Very nice, Tony. Are you bringing it to Owston?
Thanks guys! Now if only I get can a "shoddy" from DTB! :lol:

I did build the 2nd streamer, using the Transporter with an "ear" to bringing along to Owston. Since it has digital inputs and I have a CD transport also it makes for an easier demo than trying to get LMS working in isolation - just too much faff for me. Far too much like work. :lol:

Are you planning on attending Owston Greg?
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#56 Re: Yay! New toy

Post by Greg »

Tony Moore wrote: Tue Aug 22, 2023 5:46 pm Are you planning on attending Owston Greg?
Yes, should be there this year.
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#57 Re: Yay! New toy

Post by Tony Moore »

A quick update on the RTZ DAC that I will be bringing to Owston. I have split the power supplies between the DAC and the filter board, implementing a Jung/Didden super-reg on the +/- 15v for the filter.

Since there was so little space available I had to also replace the toroidal that was there before with a Block potted one as they are easier to pack in.

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It was a bit of a squeeze but I managed to fit it all in!
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#58 Re: Yay! New toy

Post by Tony Moore »

And...this is the initial RTZ DAC project, now completed with the super-regulators for the analogue filter board:

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This one uses the Squeezebox Receiver guts (the lowest pcb under the DAC board) to stream to the I2S from LMS.

I don't think I'll being this one to Owston since it's more of a deal to set up a temporary LMS and network, etc. I'll bring along the Transporter based one, which can run from CD.
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#59 Re: Yay! New toy

Post by Tony Moore »

Right, I couldn't leave this alone so I am building yet another DAC main board and trying out a few suggestions and ideas that came up with the existing builds.

This time since I needed to get the DAC pcbs made I also stumped up for the stencil too. This made the job of fitting the tiny SMDs much easier.

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The back of the pcb:

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and front:

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The main thing that I am trialing here is the use of the tiny "miniMELF" resistors from Beyschlag for the 32 "DAC resistors". They are reputed to sound nicer for audio than normal thin films, being cylindrical, plus they are cheap! I bought 150 of them and using a bridge managed to get over 36 of them to well within 0.1%. So we'll see if that makes any difference to the sound. 8)
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Nick
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#60 Re: Yay! New toy

Post by Nick »

Yep, stencils make my life a lot simpler.
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