Member
Post by peno on Jun 3, 2020 18:39:14 GMT 12
Hi Owen,
thanks for confirming the R value! I'll start a new thread here when I have something to show. At the moment I'm just butchering the donor CD player (Philips CD160) and collecting parts.
Hi Foveaux,
thank you!
-Pete
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Member
Post by peno on Jun 3, 2020 22:27:32 GMT 12
I found two prints from my DIY stuff archives, first one dated 11.02.2002 and the other one 27.6.2013 and both of them says the digital filter's resistor is 0 ohm wire. Resistor 123's (and 124) value is 27K, not 47K as in the Owen's schematic. Also the tube has cap at the cathode but it's 22n and the B+ filter cap (C135&136) are 22uF.
Here's a close up of the schematic
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Post by colinf on Jun 5, 2020 0:04:01 GMT 12
Hi Pete, welcome. If you have access to an oscilloscope and a frequency generator you can measure the frequency response of the analogue filter after the transformer, and ensure the 22n cap on the cathode is adjusting the frequency response the way you want it to. I probably wouldn’t use an ecc82 as it’s a noisy valve. Try 6n1p instead. Owen, looking at your wirewound resistor made from an inductor, have you measured the inductance? It should be zero. An actual resistor might work better as then you won’t get a rising frequency response if your coil resistor ends up having inductance. By the note of wire wound, Thorsten means non-inductive wirewound resistors with a low temperature coefficient.
AMR-iFi R&D
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Member
Post by peno on Jun 5, 2020 0:44:15 GMT 12
Hi Colin,
thanks! I have a scope but not a frequency generator (maybe I could use PC). I have ECC82 in my RIAA followed with ECC88 and it is very silent. Actually I use a "green DAC board from ebay" chinese TDA1541A board's regulated power supply as a heater supply for my RIAA. I do have few 6N1P-EVs though and could try them also if the ECC82 is too noisy. The valve stage isn't my big concern at the moment. I've made quite few (pre)amps with valves. Last Adagio DAC I had didn't have the digital filter stage at all and it used ECC99 instead of E182CC.
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Post by Owen Y on Jun 5, 2020 9:29:19 GMT 12
Owen, looking at your wirewound resistor made from an inductor, have you measured the inductance? It should be zero. An actual resistor might work better as then you won’t get a rising frequency response if your coil resistor ends up having inductance. By the note of wire wound, Thorsten means non-inductive wirewound resistors with a low temperature coefficient. colinf - do you mean the 20R w/w I/V R?
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Post by colinf on Jun 5, 2020 20:28:31 GMT 12
Yes, the 20 ohm one. You can make it 18 ohms or 22 ohms if you can’t find a 20 ohm one. The value just changes the output level so you could make it roughly between 5 ohms or 47 ohms. Without the transformer a 200 ohm resistor for I-V increases the distortion out of the 1541 dac as it’s really looking for zero impedance. It’s designed for a trans-impedance amp (current to voltage converter), where the input impedance is very low. Ecc99 would work too, it’s quieter than an ecc82. Ecc82 is at its best in driver stages.
AMR-iFi R&D
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Post by Owen Y on Jun 5, 2020 21:45:19 GMT 12
Hi colinf - thanks, yes trying a regular R was on my list of things to do (before I dropped the digital side of things back then). The basket-wound coil was done for me by a radio guy who was keen to build this project too. Lower capacitance, but I understand that inductance tends to be increase - at RFs at least.
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Post by colinf on Jul 18, 2020 18:38:38 GMT 12
Hi Owen, Have you been fiddling any more with your dac?
AMR-iFi R&D
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Post by Owen Y on Jul 18, 2020 20:25:34 GMT 12
Hi colinf - v sorry, many projects have been on the back burner partly due to busy family life (grand-child) , but thanks to discussions as above, I have ideas to work on. Thanks for the reminder & encouragement eg... - PSU troubleshoot - reduce gain - revise/upsize 5687 cathode R
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New Member
Post by markus on Mar 28, 2021 1:39:49 GMT 12
Hello, I built two Thorsten Loesch's Adagios more than twenty years ago. They sounded great. I gave them both to friends. Now I would like to build my own Adagio, but I am not able to find the schematic of the power supplies designed by Klaus Bohem, who for some time collaborated with Thorsten. Does anybody have those schematics?
I appreciated the commented original schematic of the digital module. On the bottom of that image there is the URL address of the internet page of "Thorsten's Collected Oddities". Unfortunately, I cannot securely read that address. Would you please retype that address? Thank you, Kind regards. Markus
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Post by Owen Y on Mar 29, 2021 10:34:20 GMT 12
markus - welcome to this forum. 'Thorsten's Collected Oddities' seems to no longer exist. This was at - joelist.free.fr/schematicsI remember some variation schematics by Karl Boehm for a 'D-DAC' & "Tube-DAC'. I may need a few days to find & scan them for you. Looking forward to seeing your progress, if you can kindly keep us informed here.
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Post by RdM on Mar 30, 2021 18:45:55 GMT 12
This jogged my memory, since many years ago I'd looked up what DAC was in the Queen St (Auckland) Sony Shop closing down sale price Sony CDP-308ESD I had bought (early 90's) having just missed out on a 338ESD at the same sale price. (Neither had the Philips TDA1541A, but the 307ESD & 337ESD did - two in the latter.) Some here may know this site, but since others may not - you can look up what DAC many CD players used, by brand and model: dutchaudioclassics.nl/the_complete_d_a_dac_converter_list/You can see there too a page specifically on the dutchaudioclassics.nl/Philips-TDA1541/Maybe that will help folk searching out old CD players?
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Post by Owen Y on Apr 5, 2021 17:18:10 GMT 12
Hi markus - I think this is the Karl Boehm PSU schematic, I think that you referred to (in 2 parts) -
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Post by colinf on Apr 5, 2021 19:31:39 GMT 12
From Thorsten Loesch writing on DIY Audio about his Adagio Dac vs AMR players way back in 2012: “ Even with all the mods applied this DAC barely matches the Prototype CD-777 and is still not a match for a CD-77 by a long stretch. Why? The CD-777 (and CD-77) are optimised using industrial methods and sources, not easily available to DIY Enthusiasts. This means we have for example economic access to many custom parts that you just cannot get for DIY in singles (eg. Mains Transformers wound in very unusual ways). We use CPLD's and FPGA's and have full access to any programmable functions of any of the chips (we have a programmer on staff for that) so we can implement functionality that is very difficult do to do in traditional DIY Methods (look at Eric Juaneda's Digital Decoder page - we have similar functionalty routinely in our CPLD's and need less space than a stamp for it). SMD is used aggressively and not with a view to reducing costs but to optimising performance. Usually each and every product goes through around a halve dozend reworks of the PCB layout before we are satisfied with performance (most DIY'ers would probably not go as far as our first cut layout). These are things that are not really that easy or that feasible for a lone DIY'er or a small DIY Supplier. And the results are telling. I am actually giving up on keeping DIY stuff and I'm getting an AMR DP-777, as in the final production version which I had here for a few days it betters both my own DAC and my Passive Preamp and can do 192/24 via USB as well (my current setup is limited to 96KHz). As it so happens, analog stage and the 16 Bit DAC are the same as in Joshua's CD-777 and the 16 Bit perfomance is identical.”
AMR-iFi R&D
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Post by Owen Y on Apr 6, 2021 9:55:55 GMT 12
I've loosely followed TL since his DIY analogue days in the 90s, post-E Germany. Audio DIYers, I guess, are into it because they want to 'build' & to get the best sound for the $. Every audio product has a 'style' of sound & ends up bearing the 'signature' of the designer's 'ears'. And at the end of the day, the proof is in the listening & personal satisfaction.
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Post by RdM on Apr 6, 2021 18:53:01 GMT 12
Wow, I'd meant to look up AMR but hadn't yet, then now searching from Colin's post I see amr-audio.co.uk/products/dp-777-se/Slick web page, I've yet to explore the rest. Thanks! (weird review start at end of page notwithstanding)
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