If you want to upload them here, I'll leave it in full edit mode until you're done, then I can set it to read only.
https://1drv.ms/f/s!AgwMlSh89-jUg8sISMTGKmtPFJl3vA
https://1drv.ms/f/s!AgwMlSh89-jUg8sISMTGKmtPFJl3vA
If you want to upload them here, I'll leave it in full edit mode until you're done, then I can set it to read only.
https://1drv.ms/f/s!AgwMlSh89-jUg8sISMTGKmtPFJl3vA
No problem.Thanks for the photos John. I don't know if I'll be going that far but it's good info to have. I'll definitely look into the VSR resistors. It must have been fun getting the bridge rectifier leads bent to fit the inline package spacing.
I had some time yesterday and did some work on the schematic and layout scans. I was able to get them down to a much more reasonable size without any real loss of clarity. I'll see about uploading them to the database shortly. In the mean time if anyone wants them directly by email the schematics are now 11.3mb and 10.2mb, and the layout scans are now 15.3mb, 5.4mb, 7.7mb and 5.3mb. Should be doable with a few emails.
Cheers,
James
Hi there, interesting the arrangement of the bypass film caps here. Could you tell more about the values you chose (I see 5 caps in parallel for each electrolytic) and explain a bit the benefits and effects they have on the main cap they are associated?... The film bypass caps are nichicon YX series film and foil caps, availalble from several on line suppliers. The Vishay resistors are type VSR, ultra low noise.
Preamp is super quiet, very resolving. Have got the upgrade itch a few times and compared it to 4 figure pre amps from various mfgrs, and so far the CX-1 has come out on top. (...)
cheers.
I know the LM 49720 and I used them . I used the LM4562 as well .Someone says they are identical.( http://www.diyaudio.com/forums/chip-amps/107344-lme49720-vs-lm4562.html )But ,believe me the LME 49990 and the OPA1612 sound wonderful. They are much better
I am convinced that you will not regret James. Now they are playing in my mono Power AmpDenon POA 6600 A. And among the many that I have tried are among the best. A little, bit of the LME 49990 is better too IMHOBTW Beau Geste, a little feedback. Yesterday I made a large order from Mouser and included some of the OPA1612. LOL, they may never find their way into my pre-amp but I'll be giving them a shot in the final output position in my DCD-2700 CD player. Thanks again for the suggestion.
Cheers,
James
I'm not sure that the upload worked, but I tried. I probably have to many security setting active with noScript.
Anyway, I dragged and dropped the 2x schematics, 4x layouts and 1x refurb parts list. The page seemed to react (showed a folder icon), my browser showed activity, then a window popped up telling me to sign in, then the whole page went blank and I got a "no server found" message.
Let me know if you got them, if not I'll try again.
Cheers,
James
I think you have to have a MS Live account. Nothing there BTW.
It's not like it's a real FTP or file sharing service, Onedrive is kinda limited but it's great for my cloud storage. For $99/year I get 5 1TB accounts and all the MS office 365 software on all my devices.
I got tired of chasing free storage and just paid the piper.
Hi there, interesting the arrangement of the bypass film caps here. Could you tell more about the values you chose (I see 5 caps in parallel for each electrolytic) and explain a bit the benefits and effects they have on the main cap they are associated?
Thanks.
Bypa
NP.
Bypassing filter caps is far from new in Audio Circles. Sansui added power supply bypasses with their X17 series back in the 1970s with a single large film cap, which gave many of the Sansui amps that warm sound many like. John Curl while laying out the Parasound high current designs did quite a bit of bypasses and multiple bypasses in the 1990s and 2000s with HCA series and later the Halo series..
Each film cap value will affect certain frequencies. The CX-1 has two main filter caps in the main supply. Think I used a 0.47, 0.22, 0.047 and a 0.01uf on each of the 4700uf caps. A good starting point is a .47 or a .33 paralleled with a .01uf. From there if you want to clean up an upper midrange, you can experiment with a .047 or .022. Its also important to note the intermediate cap values will have a different effect if that .01uf is not included. Now if you go smaller than a .01uf, say a 1000pf, you will clean up super treble frequencies, but at the same time change the tonal balance of the preamp.
But you can also over do it. As an example if a power supply has 4 caps instead of 2 (2 on each side of the center ground buss), may just want to bypass one cap on each side of the plus and minus supply. Doing all 4 may be a bit too much.
I also added bypasses on the phono stage PS caps.
And speaking of the phono stage, its extremely good on the CX-1. A lot of engineering efforts went into the MC and MM stages. If the listener is a phono person especially with LOMC carts, then would strongly suggest dialing the MC phono stage so its as close to ruler flat as you can get. You will be surprised at how good and organic sounding the MC carts will become. To dial in the response, you will need a NAB broadcast test disc, or similar type of LP that has the RIAA frequencies cut into it. connect a DVM up to a set of tape outputs, play each test freq. and record the AC voltage coming out of the tape loop. You can change the loading resistors to get it very flat. My favorite LOMC cart at the time was the Madrigal Carnegie One. Plugged into the MC stage on the CX-1, I was able to get the response flat within 1.5db from 30hrz to 18Khz, which is saying something. Without the dial in, most phono stages are lucky if they are flat within 5-8db, with some being a bit worse. But need to measure it before you do anything.
If you don't want to solder resistors in each time you can temp solder in some leads to the resistor positions on the pcb, clip resistors in place measure the points calculate how much is needed, plug in the resistor value. Once you have it dialed in, then solder in the correct value.
Great info! So what do the settings for the loading switch on the back of the unit actually represent? Are they accurate or a gross approximation/attempt at loading? Do you happen to know the gain applied at the MC input?
Well, I just successfully sent all 6 pages/pjg's to the AK database. At least I haven't gotten any bounce notices yet anyway. It will probably take a week or so for them to be accepted (or not). In the mean time if you want them just PM me and I can email them to you.
When I want more storage I normally just buy another external HD. I really don't like the concept of remote storage on some one else's server for my data and not being a MS user or fan I don't see a MS Live account in my future. But hopefully the files will be accepted in the AK database.
Cheers,
James
... I unplug the external drive after after each backup. With cryptolockers in the wild, one can never be too cautious.
I'd like to join the chorus and thank Bratwurst7s and the others that have contributed
to this thread. There is a whealth of information and ideas, not to mention all the
grunt work of spreadsheet, cap sizes, discreprecies etc... Fantastic effort by all.
I've just purchased a CX-1. It will undergo a similiar refurb to that outlined above.
Your work will save me many hours and help me achieve a great outcome. Thanks.
connect a DVM up to a set of tape outputs
Appears that the CX-1 enjoyed a long production run. Yamaha added
component numbers on both sides of the pcb including component
symbols eg, zener, making it a easy check before removing parts.
They also used copper screws on the back/RCA plate, the bottom and
to secure the pcb's. Serial Number E0508850Q.
Everything looked "new", very tempted to recap only psu, however
image/sound stage was not great, recapped C-40 was better in this
area, so something must be wrong... So far, all caps removed (25?)
were with spec with exception of C539 330uf/16V, measured 260uf
probably bad production.
Solder joints are ok so far.