CD-PRO2M Builder's questions and comments

SteveSun · « **Reply #60 on:** 13 Feb 2005, 03:56 pm »

Hi Larry, Josh: I finally have some time to play with the demo machine

, and I put a RF choke around the 6-wire Molex cable connecting VFD module and CD-Pro2M module.

This really improves A LOT! For those of you who already built this Kit, I suggest you get a clamp-on ferrite RF choke from RadioShack (there r 2 different RF chokes available from RS, get the "smaller" one). This $5 RF choke removes almost all treble edginess. When I put my oscilloscope probe on 5V power supply ground, I noticed there was a 12MHz noise about 10 mVp-p. This indicates that the noise is comming from the crystal oscilltor on VFD module back into circuit gound thru internal cables. After installing this RF choke, the noise reduces to below 2 mVp-p! Now, the treble edginess that I was talking about is gone...

tianguis · « **Reply #61 on:** 13 Feb 2005, 04:10 pm »

Steve:
Ken told me about this and I already did it. It works!

Larry

kelvincoq · « **Reply #62 on:** 13 Feb 2005, 09:26 pm »

My CD-Pro and DAC kit (from Audioparadise) have only been up and running for less than 20 hours. I thought the harshness on mid-high (e.g. suprano) would be eliminated by more run-in time. But as soon as I put on the choke the harshness gone.
Still there are areas that extensive running-in time would help, e.g. extending the highs, widening the sound stage and moving the sound stage more backwards from the speakers.
Next I will order the new clamp and black tray from Ken. Tianguis has valid views on the new clamp so I must give a try.

heathman · « **Reply #63 on:** 14 Feb 2005, 03:51 pm »

Hello I just got a kit in the mail from Ken and am beginning to assemble the chassis after stuffing the boards. I have a couple of general questions and maybe a tip. I am new to CD's as have always found the sound to be quite inferior to good vinyl. My turntable motor droaked and went off to the hospital and so I am on a quest to see if there is any hope for digital at my house. I thought I'd try this kit and also went and bought an Audio Note CDT-2 to use as a reference for comparison. I bought it used since they are revamping their product line and so figured if I chooses to sell it I won't have too much of a bath. I just hooked it up over the weekend, trying several digital cables and am very astonished at the improvement in sound over a midfi unit I have used previously.
I chose to slip a small piece of heatshrink tubing over the end of the bracket on the VFD boards and poked a small hole in it with my scribe to insert an insulating washer and then added one more nylon washer and found this to look a little cleaner than applying electrical tape to the circuit board under the angle bracket. I also added a small terminal strip on the top side of the AC connector on the rear of the unit to attach a chassis ground and all the transformer primaries.
My first question is about the 6 transformer primary wires that need to be attached to the IEC connector on the rear of the unit. This seems like a lot of wires to solder through a small hole and I am wondering if that is how others have done it or whether my idea of tagging all of them to a terminal strip an dthen running only one wire to the IEC plug makes sense. Also the primary wires from the T25 V transformer seem way too short if I mounted it in the right place and wish to know if it is mounted correctly and the wires ARE to short, and if so what others have done; just use a piece of heatshrink to attach a length of one of the other transformers primaries (that are way too long).
It seems that the 'Molex' harnesses are all about twice as long as necessary even when routing 'on the deck' and am wondering if I am not routing them correctly or if I should later cut them and make them shorter.
I think that's all for now. I wanted to say hi and I am glad for this group.

rmihai0 · « **Reply #64 on:** 14 Feb 2005, 04:16 pm »

I am looking for someone to put togheter a CD-pro2 m kit for me.

JoshK · « **Reply #65 on:** 14 Feb 2005, 05:13 pm »

heathman,

I have had the same idea about wiring the transformers and did a similar thing with electrical tape on the VFD brackets (but I like the heatshrink idea better). Great minds think alike eh?

I don't have the answers to your questions but think that a terminal strip couldn't be any worse than a so-so solder joint of 6 primaries to a solder lug.

rmihai0 - I am putting together kits for some people but am backlogged currently, so I probably wouldn't get to another for some time. You may inquire with Steve about whether he is building kits as he mentioned he might.

SteveSun · « **Reply #66 on:** 14 Feb 2005, 06:25 pm »

Hi heathman: this is way that I did my CD-Pro2... I soldered a piece of bare wire to
http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&product%5Fid=64-3085
and solder all transformer primaries onto that piece of bare wire. Then all you need to do is to snap this connector onto the power socket.

tianguis · « **Reply #67 on:** 14 Feb 2005, 06:55 pm »

Heathman:
The 25 v primary leads are too short. As you suggest, just use wire trimmed from another primary.
I crimped and soldered both sets of primaries into a 12 AWG 1/4" female connector, which snap onto the IEC terminals. Make sure you twist all the AC leads to reduce EMI and route all the signal cables at right angles to the AC's
I'm also an analog guy (Teres/Redpoint), but the CD-Pro continues to impress me.

Regards,
Larry Welsh

heathman · « **Reply #68 on:** 14 Feb 2005, 08:14 pm »

Thanks guys for the answers and tips so far. I will do. It looks from one picture on the web like primaries from the two T25's are attached to the bottom (or line side) of the line switch and the primaries from the T25V (VFD power) are attached to the top side of the switch. That would mean that the 5&9V supplies are hot all the time which doesn't make sense to me. I guess this brings me to the wiring of the standby switch. Somehow I missed this point and maybe some kind fellow would point out the location in instructions that discusses this. Also I wish to find schematics of the power boards and all I could find are the three pages of the VFD, output, and sensor assys. I'd also like to know more about upgrades coming too because a buddy at work who reads chinese says the DIYzone.net pages describe many upgrades in the works and he says he will wait a couple more months to see if he wants one to see how things shake out with refinements. We are all going to want to tweak and refine our decks the best we can and there is no reason us Guinea pig folks want/have to lose out for being first. For us non Chinese folks it is impossible to figure things out from just looking at the pictures. I will make sure to get a couple of RF chokes for the vfd power harness and to trim and twist/route the AC wires after initial shakedown. I will also plan on ordering a few spare tiny molex plugs and shortening them when the time arrives. Am I the only person that had to drill out the plastic screw hole on the output pcb for the optic plug? There should have been a self tapping screw for the plastic but since there wasn't I enlarged the hole to 'custom thread' in a short hex machine screw. Finally I couldn't figure out the suspension for the CD-Pro deck. When I set it into the brass 'things' and inserted hex stop screws, the deck effectively is locked and has no suspension. I guess if this is going to be immediately replaced by sorbothane I won't care, but otherwise would like to know what sort of spring action the deck is supposed to have once in place. Perhaps I didn't do it right.
thanks, Heathman

SteveSun · « **Reply #69 on:** 14 Feb 2005, 08:26 pm »

Hi Heathman: I and Ken read chinese, and we will keep people updated about all upgrades. Some of those upgrades done by some people in Taiwan do not make too much sense to me. (Change things like Black Gate caps, use different type of by-pass cap... To me, Nichicon Muse and Sanyo OS-CON are quqlityt parts, and there is really no need to spend a lot of money on caps.) Some people even tried to mod the power regulator and causes some oscillations, and started to blame on diyzone.net. So far, I tried the following mods and these really help the sound of our demo machine:

1. added pulse transformers
2. change 2 electrolytic caps on digital board to Nichicon Muse
3. +5, +9V power supply C7, C11 changed to Nichicon Muse
4. added a RF choke on the 6-wire molex cable from VFD panel to CD-Pro2 module. (you may want to loop the cable around the RF choke.)
5. twisted power supply primary and secondary wires (I use copper shilding tape instead).

People in Taiwan also tried to put "pure clock" into CD-Pro2, but this may cause some problem, and at this time, I do not suggest people to try pure clock (this is like doing heart surgery).

I will keep doing experiments on our demo machine and report all possible mods. Regarding the power socket wiring, please use the hints by Larry.

JoshK · « **Reply #70 on:** 14 Feb 2005, 08:38 pm »

Hi Steve,

I agree that Nichicon Muse from everything I have read seems to be good stuff and changing to Black gate doesn't make as much sense and some other simpler things like e.g. maybe adding some sorbothane under the transport instead of springs, etc.

However, I have a friend who is quite knowlegeable and experienced DIY'er and former engineer. He said in his mind that Nichicon Muse is great for power but not a good choice for digital. I'll ask what he thinks is good for digital.

tianguis · « **Reply #71 on:** 14 Feb 2005, 09:22 pm »

Heathman:
If the transport screws on the suspension mounts are run in too far, they'll lock the suspension. You only want to screw them in far enough so that the module can't fall out during transport, without actually touching the legs of the module. I use some nuts to lock them in that position.
I had to tap the optical socket. That's why they call it "DIY", eh?

Regards,
Larry Welsh

SteveSun · « **Reply #72 on:** 14 Feb 2005, 10:12 pm »

Hi Josh: I actually tried Sorbothane isolation pods myself, but they do not make much difference. About caps for digital, some people said elctrolytic caps are OK, but some other people prefer OS-CON or silver mica. To me, I like less caps on signal path. Larry tried my mod on the digital board (no output caps on digital signal path), and I will look into my mod more carefully before announcing it in public.

Heartman: I will find you a link to the power supply schematics. Here are some design princicles: both +5V and +9V power supply use 3 stages of regulation:

1. first and second regulation stages are typical LM317 regulators (you can read LM317 datasheet for more details about adjusting the output voltage, improve ripple rejection, and so on).
2. the third stage is a series regulator design, and it has sever componets: (i) sampling network, R10 and R11. R10 and R11 samples the output voltage and send the output voltage sample into OPA134 for comparing with 5.0V voltage reference. (ii) voltage reference: LM336-5.0, and LM334 provides constant current for LM336-5.0. (iii) varaition amplification: OPA134 amplifies the difference between the voltage reference and the sample of output voltage. A simple calculation: for 9V output voltage, R10 = 200, R11 = 249, and these 2 resistors form a voltage divider. For 9V output, the voltage sample sends back to OPA134 is: 9 x R11/(R10+R11) = 4.99V, which is very close to the reference voltage. If the output voltage goes either above or below 9V. The voltage sample sends to OPA134 will not be the same as the original 4.99V, hence OPA134 kits in and amplifies this voltage difference. The output of OPA134 drives TIP122 to control the flow of electric current. The base resistor R9 in between the OPA134 output and the base of TIP122 is to avoid parasitic oscillation. The very last end of these 2 regulator boards is a output cap C11 in parallel with the circuit: this cap is going to store some electric energy and it will help to reduce (high frequency) output impedance of this regulator.

I hope this will help, and I will find the schematics and post the link tomorrow.

tianguis · « **Reply #73 on:** 20 Feb 2005, 01:24 am »

Anybody:
I've been trying out DIY cables with the CD-Pro and thought I'd give some impressions.
When I first built it, I had some weird experiences with echo and very strange imaging with the digital output. I swapped some cables (after doing a bunch of other stuff) and found out there was nothing wrong with the Cd-Pro, which played normally using analog output.
My primary digital coax has been VH Audio cryoed Pulsar (6') using Eichmann silvers. I've also tried StraightWire and Petra coax. Today, I made a coax using Belden D-75 Silver Sonic true 75 ohm wire (3') and Eichmann coppers. This cable has eliminated any lingering questions I had about the performance of the CD-Pro: bass is tighter, decays more extended, imaging better, detail is better, dynamics are improved, any hint of digital nastiness is gone. When I stuck in one of my DIY Bybee "slipstreams", all of the above improved a bit more.
In a word or two, the CD-Pro seems to be very sensitive to proper cable choice. I should have anticipated this, given the design and components. At any rate, the sound is much improved from what I was using, which wasn't a synergistic match.
AND, I heard the RAVE get-together here in Manhattan! Sorry I couldn't make it.

Regards,
Larry Welsh

lonewolfny42 · « **Reply #74 on:** 20 Feb 2005, 03:12 pm »

Quote from: tianguis

AND, I heard the RAVE get-together here in Manhattan! Sorry I couldn't make it.

Oh ...Larry, ....you missed a very good one ! ! ! !

Chris[/list:u]

westiebj · « **Reply #75 on:** 22 Feb 2005, 01:48 pm »

Hi all

Just finished building all the boards. No problems encountered so far.

Thought I'd check in and make sure there are no changes required before I started powering up. Read through all the post's here and everything ties up.

One thing though .. I checked out the diyzone.net website for some ideas on moving the display board and drive forward and noticed an article with pictures showing U3 on the +5v and +9v PSU boards assembled the opposite way as shown on the board. Is this correct ? Unfortunately I can't read Chinese.

Here is the link :-

http://www.diyzone.net/article.php?sid=555 (You need to scroll half way down)

Thanks for any help

JoshK · « **Reply #76 on:** 22 Feb 2005, 02:43 pm »

This is more or less what I am doing with the display board for Gordon's CD kit.

By the way, I have been dragging slowly on this build but I fired it up yesterday and tested all the voltages and it looks like everything is in order despite myself.

tianguis · « **Reply #77 on:** 22 Feb 2005, 03:28 pm »

Westie:
Looking at the page you linked, there are two pics of U3. The second shows it oriented the way the board is printed. I can only assume he built it improperly, then fixed his mistake. My Chinese is a bit rusty, too!
I built mine with the U3's oriented as printed on the boards. Voltage checks before hooking up the CD-Pro module showed the voltages to be spot-on.
Here's another display board relocation:
http://www.diyzone.net/article.php?sid=552

Regards,
Larry Welsh

SteveSun · « **Reply #78 on:** 22 Feb 2005, 03:36 pm »

Hi Westiebj: U3 should be installed according to the PCB printing, do not invert U3. However, Q5 on the CD Detection Module needs to be inverted. Please check the picture on top of page 16 of the installation manual for Q5 and the Molex socket on CD detection PCB. Thanks.

JM · « **Reply #79 on:** 23 Feb 2005, 06:18 am »

With some luck, I should be done with mine soon.
All PS's check ok.
I returned Ken's demo unit today and he mentioned some one who had grounded the transport to chassis and got better test results.
But I couldn't really understand where the connection was in the transport mechanism...
http://www.diyzone.net/modules.php?op=modload&name=Forum&file=viewtopic&topic=71406&forum=3
I was wondering if the chassis should be connected at the AC power input or not. I couldn't find any mention of it in the manual...

CD-PRO2 kit at JM as of 2-22-05: