MHZS - Mystery of the DAC Chip

More of Xiang Sheng 708B Mods:

Some holes are too tight and can be drilled carefully and slowly.

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The tube sockets are instable. Tube sockets of MHZS are much better.

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The bleeder resistors are optional.

Some Caps do not discharge after switch-off. If you guys like to work often on the PCBs this could be useful. On the beginning of this thread I posted a picture of a removed PCB of the CD66. After some hours the 0.1 uF cap ( the white multicap) is charged with approx. 40 V. This resistor discharges for example this cap. So you must only wait for some minutes and can take the PCB in your hand without getting electrical shock!

After complete modding you can solder the resistors out.

In the little amp I willl let them in, because it works on 260 V! I want to feel safe.

Changing for better Yageo resistors. Yageo has thicker connecting leads.

...

...

New Caps are often a problem because of their largeness.

Search a good position and then use heat shrink tube for isolation.

Between amp and headphone connector there has been a very simple elCap with 150 uF/200V. Searching a solution with film caps has been unsuccessful ( the price f.e. 75 caps in parallel on every side with 2 uF is horrendous !)

As alternative you can use low ESR caps (with some headaches) and increase the value. Increasing this value took a great effect for the deep bass. Parallel I soldered some small polypropylene film caps. Some which have been flying around here.

Trying to fix that Cap Blocks showed to me how they have to be arranged. It look not so good but they can be exactly fixed in that case.

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A short comparison between USA and Russian Military tubes:

The JAN 5670W is a really fine driver tube for amps. The Russian 6N3P-EV makes a lot of hum in my 708b.


The 6N23P-EV from Russia accentuates more the mids and sounds very strong and sonor. You feel the thorax of the singer! Maybe better for classics / jazz.

The Sylvania 6922 has a better balance between the bass and hights, but is not so warm. I think better for modern music.

Both are very clear and dynamic but set different course. It depends on your taste.

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hi alfcat,

These photos are downlod with other web site, which is quite clear for modification for your reference.
my dac-ah have no changed the dioides anymore. beacuse i don*t like sound fast, i like it like as tube sound. The sound of  TDA1543 is close to tube sound.
your dac-ah is  old version.

if you want to mod it, can call me to discuss.

thanks.

[quote:7a8cdd8803="alfcat"]Dear KiKo,

Haven't seen you for a week and you were hiding in your garage to fix this whole thing.

Looks very interesting to me but honestly I lost track as you proceed.

As an amateur, I realised that you added some huge capacitors. You did this to ensure a steady flow of power to the DAC / Analog part? Instead of using an extra Power Supply, you can capacitors instead?

If you can afford the time, can you explain? I know that you added in a lot of stuffs but I don't know what is the purpose of adding them ...  :cry:

CAT[/quote]

Hi Alf,

no no, I havent been away to fix that whole thing. It has been fixed earlier. Looking at the Digicam I noticed that I shoot too much pics. After choosing some pics to upload I found out that the upload time of HiRes Pics took too much time for upping. It took long to find a prog which can mass resize. Thats why I gave the link to FastStone PhotoResizer. Such a free prog is not easy to find. In fact I am just searching for a prog for inserting text into a pic. Thats the reason why I upped the pics which are not so easy to understand. Do you have a tip?


......"a bit on the logic of going through each and every step"

I will try.

By starting a mod I build out everything (ex. the transformer and display) and take a look on the PCBs and study the circuit paths.

At this point you can believe that all Players have nearly the same conception. I search the electronic devices -Digital, DAC, Amp, Drive, Signal Paths and at least the complete PSU on all boards. Thats easy, you must google all datasheets on the net. In the datasheets you see the input, output and psu paths of EVERY device. (thats a good chance to inform about every chip). Then you follow the tracks and try to learn by rote.

After some days you will have a good overview.

Then I google for better spare parts, that takes longer time. Of course you need an approximate calculation before purchasing. So I am wondering about guys who use in the same signal path electrolytic caps and expensive JensenCaps. I cant understand that. I prefer another balance:

If somebody wants to spend much money he should purchase fine caps like the Jensen or Mundorfs or US made for the complete signal paths, and if not I would prefer good PP like the red WIMAs for the whole circuit.

You have seen I have mixed some caps. Thats why I had a lot of things at home, only the rest I purchased.

-----------------------------------------------------------
" I lost track as you proceed."

My track is: replacing all resistors in signal path, all diodes. Before substitution of the caps I study the PCB. The question is: Where is every of that caps connected? When you get an overview you know his function.

For this overview I updated the pics or the bareboard PCBs.

Then I try to distinguish. I must do that because I like to replace with much bigger caps. Much bigger caps means that the voltage suppliers and the transformer will be very hot. Thats to avoid.

I see that in that way:

1. If a cap is only for the voltage of a relay, like the one cap in the pic in this post it is not neccesary to change. (I changed it only because the price for 10 piece of Pan FC is much better). Usually its an absurdity to have an Pan FC for the output relay.

2. When I see that much devices share the same voltage (because they are connected together in the circuit) I increase them a little bit and if possible I try to detach the voltage supply. Here I have detached the 3.3V supply for the DAC from the +5V from the supply of the dig filter chips in front of the player.

The method, it doesnt matter if a Teac VRDS or a good DVD Player or our MHZS, is everytime the same. I try to give to the devices separate voltage supplies and more current. You can see it on the first posts with the Teac and Denon.

One tip: As more you separate as better is the sound result. But this method is limited - or is here anybody who would make a separate PSU for every chip inside?

You asked me why I am not using an extra Power Supply.

An extra Power Supply is not needed. This players have a very good PSU in my eyes. The transformer has very much separate windings and is strong enough for a little amp. MHZS has separated very much inside, you see it on the quantity of the diodes built in.

The high frequency coming in from outside is killed by the first filter (before the transformer), the HF Problem inside will not come if you use very fast and soft recovery diodes (instead of the standard diodes which have a HF click every time when the 50 Hz wave reaches the 0V point) and the rest of HF will be eaten if you use a low ESR cap. So the low ESR cap has 2 functions: It gives the energy faster to the devices and shortens the HF. The HF has a higher resistance to get through your board as to a cap which is a low ESR. You must not use Panasonic FC. There are better on the market, but they are OK and the price is fine.

I prefer a lot of Pan FCs as a better solution as a change of only 2 or 3 caps to a blackgate, which are of course better for audio, but for the same price.

Thats what I meant with balance in modding. (and the Jensen/elCap combination).


In combination with the post on page 4 I want to say that modding (changing a cap for a better one) is more. I try to understand the way the developer has gone and flow with the circuit.

Every mod and result is a question of investment. I wont deny that its possible to make a better player as I have done and it makes sence to separate more in the PSU and purchase f.e. silver in oil caps. But remember guys - this players use the PCM1742 which is low budget and developed for good portable MP3 Players and DVD Players.

I am sure you heard of the fine new Wolfson DACs. Arcam, Cambridge and the new Pioneer D9 use them. And I was shocked by finding out that the new Ipods use them too. So I believe the eye of a needle is the PCM1742 Chip. So I can understand that you try to avoid that by experimentalise with other DACs.

Till tomorrrow......

Alf,

I know the Headphone amp is not interesting for you. But please take a look at it, it is the same method as for the player.

Another question is going through my head..............


An example: I have a second DVD player here. It has a remote, full waranty, plays everything, pics from SD Card, from USB and has hundreds of functions. I payed 30 Euros for him.

The MHZS costs as 15 of this DVD Players and plays only music. Why isnt it possible that the manufacturer builds in some better devices, at least some Pan Fcs or MKP-WIMAs in signal path for example at that price?

[quote:ea3c928d95="Kiko"]

The MHZS costs as 15 of this DVD Players and plays only music. Why isnt it possible that the manufacturer builds in some better devices, at least some Pan Fcs or MKP-WIMAs in signal path for example at that price?[/quote]

Good question Kiko!  and also why do MHZS use a cheap dac chip which is also used in cheap DVD's  and they advertise they fit their own designed dac chip which is lies :wink:

Dear t.,

Say is it possible to swap to another DAC chip? I haven't been following too closely these days 'cos busier than the bee .... :cry:

CAT

ALFCAT,
MY MOD CDH-AH PHOTO :

Dear Viewer,

Wow, how much did you invest in that thing? I can see you have a separate clock like the CD 33; at least 4 heavy weight Caps lying on both sides and film caps on top of the Philips ....

After rushing for 3 weeks, I feel really sick. Many of my F.5 boys got this "Hand, Mouth and Feet" disease and they are urged not to go back to school. Currently I am suffering from a flu (at least I think it is) as well. Just hope I can recover soon.

Thinking of DIYing a Marantz 7. Any good suggestion or where to get the board and the components?

CAT

hI ALFCAT,

You can try to this web sit, it has Marantz 7 pcb and material and other pcbs for diy:
http://www.diykits.com.hk/
costs around for pcb and material aroun $700.

thanks.

Hi,

at this site diykits has some interesting DACs, Zhaolu and Citypulse and a really cool solid state Headphone amp. Did anybody bought one and can describe the soundstage?

Hey,

here in Germany there are some guys modding the CD33 with fine ideas:

Here is one picture that should interest you:

Bypassing the op-amp is a good mod :wink:

Dear KiKo,

I haven't bought much items from diykits. VIEWER got more experience with this shop.  All I know about this shop is where it is located and the owner is a pretty nice middle age man.

Thanks for posting the schematics. I hope my colleague can read it as I can't yet. Will try to learn more about electronics next year when I have more time.

CAT

Dear t.,

From you photo, I can see that you removed two of those caps, replaced the OPAM by putting in some caps, resistors ... and you have at least THREE? boards instead. One for the clock, what are the others for?

Do you think you can draw us a schematic too for your modification?

CAT

Found on an french forum for MHZS, but dont understand the language.

We can discuss.........

About the schematics, the last one is the one from machmat in holland it has a 12 db low pass filter to cut of high frequenties. This the one who started the passive filtering of the MHZS player.

The first schematic is of mine hand. This one has a 6 db filter and i find out i like it better.

But the last 2 MHZS players i modded i leave also the 330pf capacitor and do not change the resistors near the tubes. This sounds best and you do not buy any parts for it. See below.

Dear Koifarm,

So finally how do you fit your DAC-AH into your CD33. Your first trial was that you don't like the fitting very much.

I got mine at present as an external. When we move into the month of December, I should have more time for DIY. First, I think I will fix the DAC-AH "out of phase" problem. Second, I hope to seek help from people like you, Blair, KiKo and others in helping me fix my good friend's KT88 Amp. Lots of interesting work coming up.... :wink:

CAT

Dear Alfcat

first - i used a separate transformer for the DAC-AH, since you bouth the complete Lite DAC-AH you have already one. I used a small torriod type.

second- i do not used the opamp section on the DAC-AH board. I got the output from the I/V resistors. I also do not apply voltage to the opamp section.

third - With the output from the DAC-AH i go to Input as discribed before on the capacitors from the MHZS player.

fourth - Connect digital out MHZS player to the digital in from the DAC-AH.

The board fits upsidedown in the MHZS player.

I will try this week to upload some pictures.

The DAC board without the tube section sounded like my shanling T100se
with the tube section attached you get the fine tube sound i liked from the MHZS player only more detail and better soundstaging and no noise :

Dear Alfcat

I saw this http://www.design-technology.info/electronics/. This is maybe useful to extend your knowleg of electronics.

Hi,

a very interesting and always updated overview about used DACs and Transports for comparison you will find here:

http://www.vasiltech.nm.ru/files/cd-players/CD-Player-DAC-Transport.htm

Dear friends,

Three weeks from now I should be free from the busiest months of the whole year. Really long for that time that I can try out what you guys had suggested to me in the last few weeks.

CAT

[quote:eebc4c06d2="alfcat"]Dear t.,

From you photo, I can see that you removed two of those caps, replaced the OPAM by putting in some caps, resistors ... and you have at least THREE? boards instead. One for the clock, what are the others for?

Do you think you can draw us a schematic too for your modification?

CAT[/quote]

The op-amp bypass mod is basically the same as the schematic Kiko posted.

The smallest board is a diy discrete regulator supplying the dac,  the one with the row of red caps at the side is for the pre regulation feeding the small discrete etc.
The other board is for the XO (clock circuit)

I'm currently building the AYA dac designed by Pedja Rogic ,  just waiting for some parts on order

Hi alfcat,

I very happy for the job of CAYIN CDT-15"s modification, i posted it for you sharing:
the white colour square areas is modified.
Its sound is better than Cambridge audio 840 cd in my feeling.
there are two clocks one is for transport and other for up-sampling
thanks.
http://i107.photobucket.com/albums/m289/viewer_2006/cdt-15a.jpg?t=1196060622

Dear Viewer,

I tried to look around for Cayin CDT-15 but there isn't anymore. What a pity .... Two weeks ago someone put one up but it was sold almost the other day.

Just got my Marantz 7 .. ha..ha.. will spend the next few weeks working on it. And t, Koifarm, etc. posted some interesting stuffs above.

CAT

All, just found the website of mhzs
http://mhzs.b2b.hc360.com/ and the chinese name of mhzs is 梦幻之声
company name is 佛山市禅城区梦幻音响厂.

Hey,

I have found a very interesting DIY Shop. Hot Sets like DACs with 15! voltage supplies, up to 4 PCM1704s and discrete analogue output stages for moderable prices are here, with OSCONs, ELNAs, VISHAY DALE and........:

http://www.audio-gd.com/enweb/en-diy.htm :shock:

Hello,

is somebody there who could help?

To telephone to Mr. Kingwa from audio-gd.com and ask him a lot of things?

Kingwa speaks chinese language and it would be a great help if somebody here could talk to him, inform about his products and translate it to English here at hififever.

A part of his website is translated to English, but his chinese websites seem to have more information. A sound comparison of that great product portfolio would be very interesting.


Here a copy of the contact:

Finished Product  Inquiry  Phone:   13726387280  Qinghua He

DIY Technology Forum:                 http://bbs.audio-gd.com

Components  Inquiry Phone:          0757-22860490  Ms. Zhong

Tel / Fax:                                     0757-22381191

E-mail Address:                             audio-gd@126.com

  
联系地址：  广东省佛山市顺德区大良家电城146-148号
Contact Address:  No. 146-148, Daliang Electric Appliance Plaza, Shunde Distric, Foshan City, Guangdong Province

Thank you.

Dear KiKo,

Will come back on your issue later after I finished everything by the weekend.

CAT

Dear Alfcat,

So far we have this information of Kingwa.


---------------------------------------------------------------------------------------------

On DACs there are small red adjustement things, what is that? What must I adjust when finished? (here:http://www.audio-gd.com/Pro/dac/DAC8/DAC88.jpg)-----------------------they are switch, when you updating the PMD100 to other type DF, like DF1704,SM5813, you can adjust these switch to let it work.


What is difference between DAC17A and 17D?-----------------------------DAC17A is soft,  DAC17D is have more dynamic and in focus.


RC-1 DAC, is this a clock for DACs?---------------------------------Yes , but we only sell it to our DAC user.

Can you give me please all prices?
DAC8 is USD1175
DAC11D£º     USD 870.00
DAC9£º    USD 1050.00
DAC17D£º USD 660.00
DAC1    USD  450.00  (Without Postage)
DAC-3

Using 4 Pieces of PCM1702£º  USD 480.00

Using 4 Pieces of PCM1704£º  USD 590.00
DAC-4

Using 4 Pieces of PCM1704£º  USD 630.00

The price is without postage.

and you can see our English Web,

http://www.audio-gd.com/En%20audio-gd.htm



And can you a little bit describe the sound of your DACs? And Headphone Amps for HD650?

DAC8 is very Hi-Fi, it do not emphasize any sound ,but you can hear any sound in focus.
DAC9/11 is more Hi-Fi, but they have a little musical,
DAC99 is very Hi-Fi,  compare DAC8/9/11,  DAC99's bass is lack a little.

DAC17, it can emphasize all sound, you can fill the bass is strong, intermediate frequency is rich, high frequency is clear,  compare to DAC8/9/11/99,  it lack a little clear.

DAC1, the bass is strong, intermediate frequency is rich, high frequency like some electron tube

DAC3,the bass is strong, intermediate frequency is rich, high frequency is clear than DAC1.
Kingwa

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Very interesting would be answer about chip rolling like tube rolling. For example:

"DAC-3 Decoder Kit  
Using 4 Pieces of PCM1704UK (1702)
supports users to upgrade PCM63/1702/1704"

Does Knigwa gives an instruction for adjustement for the DIP switch?

And the Diykits, what is included and what not? The transformers and cases semm not to be part of the sets. Furthermore there are some interesting modules which I dont understand......There are ML2      
Different Voltage Gain Modules, Current Transmission Modules, IBM (Integrated Basic module), and so on. Can you please ask which function they exactly have and if there must be purchased separately or if they are included in the DACs, Preamps and so on.

The http://www.audio-gd.com/enweb/pro/diy/zd.htm....it looks very good. Is that module for additional other products as Kingwas because Kingwa has integrated them in hid Diy-Projects or should they be purchased with his products?

And is there a lot to adjust, is an oscillograph needed? Most Diyers dont have one, me too.

And at least a bit more about sound of that things......

The website http://reizaudio.wordpress.com/ seems to be from Kingwa too, but this one is only in chinese language. Maybe there are more informations.



There are a lot of questions..... Alf, thank you very much for doing that all for us and for me!

Kiko

Dear KiKo,

Yes, there are LOTS of questions and I am a bit confused. Sorry.

Can we just start off with a few so that I can make sure I got the answers for you.

What do you want to know in the FIRST place?

I don't think I can call the person up. He lives in China and he speaks Putohghua. I speak Cantonese ... completely different dialog.

CAT

Dear Alf,

Thank you for helping. In the meantime I had a longer chat with Kingwa and he gave me a lot answers, so at this moment it is not neccesary.

I am sorry I didnt know that you speak different languages, we dont know here to much about it. The signs on far east pages seemed the same because I cant read it, so I have thought that you speak the same language. ops:

After accepting delivery maybe there will be something questionable, so we can try later. But how can you get an answer if you speak another language?

Kiko

Dear KiKo,

In Hong Kong, we use Traditional Chinese (written text) and people in China use Simplified Chinese. We can manage to read both. The worst case is I send Kingwa an email.

Second, I don't know Putonghua but there are others, including my wife, that knows the dialog. Therefore, it won't be a great problem.

CAT

Dear Alf,

I have it now. Can you please translate it?


++++++++++++++++++++++++++++++++++++++++++++++++

Hi!Kiko:

1. In next time I want to buy your RC1. How to install - in chinese?
How uninstall RC1? The steps with your picture from yesterday.
----------------------------------------------
安装RC1: 将RC1模块上连接好的电线连接到图中 STEP 1 所示位置.
将图中所示 STEP 2位置的两个用焊锡相连的焊盘分离,
将图中所示的 STEP 3 的开关"1" 打到OFF 状态,即这个开关 "1"与"2"是OFF, "3-5"是ON.
在图中RE-CLOCK 位置的插座上插上RC1.

拆去RC1:将RC1的电线从STEP 1 处焊走,
将图中所示的STEP 2 两个焊盘用焊锡连上
将图中所示的STEP 3的开关"1" 打到"ON"位置.

2.replace SM5840-how to set a new DF - maybe DF1704 in place where has be SM5840. How to change sharp/soft after replace in cd player?
使用DIP28的转换板,这将不能将DF1704直接焊接到原CD机中SM5840的位置,只能尽量短地将DATA,BCK,WCK等输入输出端口用引线连接,再接上+5V与GND,架空在原SM5840上方.
你需要告诉我你的CD机使用的DSP 与DAC的芯片型号,或将CD机的线路图发给我,这样才可以预先设置好DF1704的状态.
从DF1704的PIN27连接一个开关,通过这个开关就可以控制声音的SOFT/CLEAR

3. In your DAC - sharp/soft DF1704.

That will help very much if you can write it again in your language, please.
--------------------------
图中所示的开关"2",拨到ON位置是SOFT,拨到OFF是CLEAR,
如果方便操作,你可以将开关拨到OFF,然后在机箱后面安装一个拨动开关,开关如图所示连接到DF1704的PIN27及GND,这样就可以在不打开机器的状态下控制
Kingwa

++++++++++++++++++++++++++++++++++++++++++++++++
Thank you !

Kingwa has added this picture:

And this one:

---------------------------------------------------------------------------

Hi!Kiko:
Sparrow 是专门为 Sennheiser 或音色偏温暖或中性的耳机设计制作,
它的声音表现较中性,平衡,而稍带有一点甜美,
作为一个前级使用或缓冲器(BUFFER)使用,声音也会表现得很清晰而甜美.
它有一组RCA输入,一组RCA输出,一组耳机输出,应用了我们最新的电流增益技术.
Kingwa