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Hello! I have some unpopulated PCB's of the first edition IVY's. Have you ever tried out the differential op amp LME49724 for the IVY? If using the IVY to buffer voltage out DACs such as your OPUS or the AD1852 chip, with input/feedback resistors much higher than for the Buffalo I/V stage, wouldn't the input bias current thirstiness (2uA) of the OPA1632/THS4131 become a drawback? Another question: I also have an unconnected OPUS still lying around, and haven't got the manual for the IVY I with the proper component values. Any chance you could make it available again, perhaps with a link from the IVY - subsite? best regards audiophile, Oslo, Norway Edited by user Saturday, June 5, 2010 10:42:38 PM(UTC)
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Hello,
Yes I have used it, and yes it works great.
The lower input bias current is definitely a plus especially when as you say the input impedance into the IC is higher. But it is sufficiently low on both chips to not cause any headaches. :)
The OPA has somewhat better specs regarding bandwidth and slew rate, but honestly not enough to make it a lot better.
I have not done any formal testing between the two chips. But, they both sound excellent.
I will see if we can get the old documentation up. What version of Opus is it?
Cheers!
Russ
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Hi again! (and thanks for answer)
The Opus version is the 2.1.
best regards
audiophile, Oslo, Norway
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Hi
I have also sent an email to twisted pear, please ignore that question regarding the IVY stage.
I am also to build an old version 1.0 of the IVY stage. Could you please provide me with the old doc.?
I am only to use the SE output. Can i discard some of the components at the balanced stage?
Regards Mikkel
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Hi Brian
Thank you very much for your reply and the links.
Under additional notes you do say that versions prior to version 2 have a slightly different reference descriptors(part names) and values. Is it possible that you please have the older schematics, BOM list and manual for the V1.0 of the IVY?
The resistor numbers seems almost correct, but the capacitors are of different numbers. I am to use the IVY with a COD and according to the IVY manual (table 1a 2VRMS) i can omit the C1-C4, but they are all located on the left side of the IVY V1.0
Thanks again
I will post questions at the forum in the future for the benefit of everyone, so please ignore my previously sent email :-)
Regards Mikkel
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Hmm, I'll dig around. That was a long time ago... :)
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Can you post a picture of the board?
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 IVY 1.0.jpg (154kb) downloaded 12 time(s). IVY 1.0 back.jpg (118kb) downloaded 11 time(s).I am to use it with the COD V2.0, spdif module and OTTO switch. All of the other boards are with components except the ivy stage. I have a questions regarding the clock signal for the COD, but I will ask that in another and more suitable thread :-) Thanks for your help Mikkel
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Hi again.
If the layout is the same for both the V1.0 and V2.0 and only the numbering is different i can cross reference the numbers my self if you have a matching picture... The old manual and BOM list would also be much appreciated :-)
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IVY_bom_pub.xls (11kb) downloaded 2 time(s).Have a look at this BOM. Does it look right? Edited by user Thursday, March 15, 2018 7:55:31 PM(UTC)
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Unfortunately not. The highest capacitor number I see on the V1.0 board is C14. Electrolytic cap. numbers: C3,C4, C9 and C10 and two closest to SW1; C13 and C14... The resistors seems more correct, but not sure which to omit for the COD and if they are of the same number... Edited by user Thursday, March 15, 2018 8:17:01 PM(UTC)
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Hi Brian I asked around in the local hifi community and i got a photo of a hard copy of the V1.0 IVY. I have made a BOM list and used the values from the other BOM lists and compared to the other IVY schematics so the numbers now match. There are 4 capacitors running in parallel with the, R1-R4 resistors that are calculated for the current output;C1 - C2 and C7 - C8. It is a very hard to read on the schematic but i think they are 2.2 nF. Does that seem right? What capacitors, size, type/brand and voltage would you recommend for those please? There are some different op amps used for at he bom list from the documents at your webpage and the ones in the bom list you sent here. Which one would you recommend please for this "old" IVY V1.0? I have added the updated BOM list for the IVY and Photo... Regards Mikkel IVY_V.1.0_BOM_COD_20.03.2018.xlsx (11kb) downloaded 2 time(s). Resized_20180319_104706.jpg (166kb) downloaded 17 time(s).Edited by user Tuesday, March 20, 2018 10:03:27 AM(UTC)
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You can get capacitor and resistor values for the Buffalo from the BOM I posted earlier.
For the opamps, OPA1632 for IC1 and IC2. LM4562 or LME49720 (same chip) for IC3.
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Hi Again I am planning to upgrade my IVY 1.0 with a new PSU. What would you set the CCS current at for the IVY stage please? I am using 2 x OPA1632 and 1 x LM4562. I have measured the current under normal use: +15 ~43mA - 15 ~66mA Ground is matching the two subtracted at ~23mA. Would 150mA be fine as listed for the IVY III in the Buffalo guide? Could I run the IVY 1.0 stage at +/- 16v instead of the recommended 15v? The OPA1632 is listed at max 16v input... Thanks again:-) OPA1632LM4562
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The current demands for the original IVY should be about the same as the current version.
You could use +/-16VDC, but it would be pushing the limits of the opamps.
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Thanks for your reply Brian :-)
I will try to source the correct transformer or “burn off” another 1 volt on the PSU to go down to 15v and maybe increase my heat sink.
Happy holidays:-)
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