DIY Marantz 7C

In order to ease the pressure from work, I finally ordered a PCB version of Marantz 7C.

Have thought of a number of possibilities; Marantz 7, AudioNote or even Matisse and Macintosh. Saw this set at a reasonable price and finally ordered it.

Spent 4 hours going through everything in a "no hurry" manner since I learned from the terrible mistake made when modifying the CD 33.

Still looking for a good case .... that is the troublesome part. I also need a volume switch and an ON/OFF switch as well.

為了幫自己減壓, 終於忍唔住, 訂左套Marantz 7C番來玩.之前都有考慮過幾個套件; 如 Marantz 7, AudioNote, Matisse, Macintosh 等. 這個套件價格也算合理, 結果訂了回來一試.

用了四個小時來整合. 吸取了之前改CD 33 的慘痛教訓, 今次一於慢慢來.

唔 ... 重要找一個型仔case, 開闢, Volume 制.....

Let's start another thread in the 發燒鎖事 ....

I agreed to CAT sir’s point of view to the current education system in Hong Kong. Since I am not experienced educator though I have short part-time teaching experience in local university and secondary school, it is not convenient to comment too much in this forum. Just express few words of my feeling during a casual discussion of our kids.

I grow and educate locally in Hong Kong. Fortunately, I educated in the past, but not at the present. (我是土生土長及受教育的正牌香港仔) Since Hong Kong is an international city, I meet different things and people from worldwide locally or oversea in my working experience and my knowledge becomes internationalized. (i.e. I have lived and worked in Canada before and my elder son was born in Canada too)
  
In my view point to education, I encourage young kids to have better studying. I prefer to motivate them, rather than force them to do. Even up to university level, it just provides a foundation knowledge. Student who achieves poor studying result does not mean anything. There are a lot of things to learn after graduation. It is a life-long learning after work in society. As a practical guy of me, I believe people with proven successful working experience, rather than solely rely on higher academic qualification. Bill Gate gave up his university degree in Harvard university and started Microsoft. This is an example.


B. regards,
alant

Dear all,

Please be fair to the youngster today.

Compare to olden days, nowadays the attractment is much more, there more alternative as well (people tends to distract when have too many choice), become trend had changed, good in academy doesn't promise the good future...and they are other alternative....a lot rich man do not have university level of education...

Nowadays, whatever you want you can buy it easily with money, indirectly we seldom squeeze our brain to invent/devlepoment thing using knowledge learn from school. As those who do not obtain high education tend to take up higher risk & challenge.

Today's engineer do not need to trouble shooting to component level--> it is more on software, machine will give error code, anything goes wrong just replace the whole pieces of board...

Life for the future generation become tougher, they need to have good knowledge and also brave enough to explore to own business.....

A lot of people like to emphasis on IQ & EQ, in fact youngster today generally has higher IQ & maybe also EQ than old generation. But their ability to face set back & falure is much pooprer. Olden day we will not suitcide when fail the exam......so who adding the pressure on this poor youngster??
a lot people tend to think that higher education level = higher knowledge.... but is it true?

Dear alant,

You are indeed an engineer, ha..ha... Well application of your knowledge.

Frankly, I have been in the education field for over 20 years. My workload had increased more than four or five folds over these years. Unfortunately, as you said, my students get poorer and poorer; mentally, physically and morally. We spent over 50% of our time doing documentation work which I believe is useless. We stated what we are going to do and will do but ended up never got the time to do it.

Many believed that Western education is far superior than that of HK. I studied in Canada as well. The system runs more or less the same. One major difference is that kids there are NOT flooded with homework or OLE (other learning experience). Kids there got all the time they wanted to explode themselves. They are "bold" and have no fear in trying things out. That is why people got so creative and out-going.

CAT

I have the following personal opinion to the Hong Kong education system in the past and at the present. I try to adapt a mathematical model to present my point of view as below:

Assumption: The workload spent by teacher during teaching plus the effort spent by student during studying directly affects the performance of student in examination result. (i.e. it is a joint effort between teacher and student)

In the past
Let:
W be the workload spent by teacher in the past
E be the effort spent by student in the past
P be the performance of student in examination result in the past

Then, the mathematical model is expressed of:

                    P = f (W, E)

This equation explains that P is a function of variable W and E.

At the present
Let:
∆W be the change of workload spent by teacher at the present
∆E be the change of effort spent by student at the present
∆P be the change of performance of student in examination result at the present

Then, the mathematical model is expressed of:

               P + ∆P = f (W+∆W, E+∆E)

Since both of the workload spent by teacher and effort spent by student increased positively at the present, we have:

∆W, ∆E > 0

The difference between the performance of student in the past and at the present is:

               Difference = P + ∆P – P = ∆P

Case 1: If ∆P > 0, it means that the performance of student increased positively
Case 2: If ∆P = 0, it means that there is no change of the performance of student
Case 3: If ∆P < 0, it means that the performance of student decreased negatively

In my personal view point, I am in doubt if it is at “Case 1” for the Hong Kong education system at the present. In Chinese, it states 比較以前及現在香港教育制度，老師的工作量就越來越重，壓力就越來越大，學生就越讀越多書及多元化，晚晚讀到深夜都讀唔完，但我本人就不覺得現在學生的表現比以前學生好或有明顯的進步，真是一句‶一蟹不如一蟹″了。

Sigh .... not only you two guys, me having the same problem with my girl as well. I only got one at 10 but I never spoil her. Her studies is driving me crazy as well.

I really don't know why kids got so many problems these days. If we were like that in the past, we won't survive up to now.

We can always switch to another forum in hififever, no restriction on kids education there.

CAT

Dear Alant,
I understand that it is not appropriate for us to talk about kids in this forum.  But I just cannot control myself because I am having the same problem which bothers me too much and makes me loose my appetite on my hobby - audio DIY.
You are in a better position than I am because your older son is still young and you  have time to design a better circuit for his brain.  Over the last three years, I have been working very hard to look for good circuit for my younger son.  Now, it is still fruitless even I urge my daughter (my first child) to do something.  Yes, my daughter is very smart.  Having graduated from the top university in Canada, she is now doing her Ph D in neuroscience in a very famous university in Europe.  My older son graduates from a very famous university in Canada this year.  He finished his final exam in April and got a good job early this month.  But my younger son, he is still waiting for a circuit.  In high school, he did pretty good so that he could get into the top universiy in Canada for engineering.  I thought that he must be the one who takes over my electronic stuff.  At the end of his first year, he got suspended from that university.  Then he turned to college.  After one year in college, he entered a second level university for electrical engineering.  Two years later, he got suspension again.  I don't really know what he should do after this summer.   Back to college again seems to be the only way to go.  So, I sincerely hope that someone can show me a effective circuit.  Should you find a good circuit for your older son, don't forget to let me share.

[quote:eefbadc4d4="alfcat"]Dear alant,

Oh, your son is lucky then. I don't teach as many class as before. If he is in Science class (in the future), then the chance of him seeing me is minimal.

Usually I am very cautious about High Voltage, although I got 9 lives.

CAT[/quote]

Dear CAT sir,

Your school is a brand one school and famous in the district. They are in P. 4C and F. 1D in your school. My surname is “Tam”. You can know who they are by matching the class name. Although the genes of my two sons are inherited from me, they perform indifference in school result. My younger son nearly receives first prize in class or/and in same level every year, but my elder son’s result is in reverse order. May be, the genes of my elder son is still sleeping.

I think that the circuitry of elder son’s mind requires adding an OPAMP chip to magnify his capability, then passing through a series of capacitor to filter out high frequency noise and smoothing the signal. Then, his result will be better. Examination is coming in June. If the teacher (i.e. your colleagues) can provide guidance or material hints to him before examination and advise which OPAMP chip such as premium grade Burr Brown OPA627 or super low distortion National Semiconductor LM4562, and which capacitor such as high quality Jensen, MCap, etc... can fit to him. In Chinese, it states “看看他腦部綫路有無得摩機“. Then his performance in examination result will be improved.


B. regards,
alant

The board should be a LITE board. I don't know why they didn't print the name on the board.

CAT

This link may be useful for you http://www.bbc163.com/read.php?tid=2961
I think this board is come from this company.

Dear alant,

Oh, your son is lucky then. I don't teach as many class as before. If he is in Science class (in the future), then the chance of him seeing me is minimal.

Usually I am very cautious about High Voltage, although I got 9 lives.

CAT

[quote:c5ac4a9f76="alfcat"]Dear alant,

I don't mind at all. I come here to learn and any advice is welcomed.

Yes, I am in that school. If your son happened to be in 1E, 3E, 5A, 6A or 7A, I am his teacher then. If your son is not is any of these classes, then your son is VERY LUCKY ... ha..ha.

CAT[/quote]

Dear CAT sir,

I have two sons. The younger one is studying in primary while elder one is studying in secondary school at same “brand name” of your school. I have asked my son and he replied that you have not taught him yet. May be later! Your expertise is Economic. Enjoy your hobby here with technical guidance from experienced people, but beware of the safety in electrical precaution. I am also an audio DIY beginner. I also don’t understand many HiFi circuit design and need to learn more.


B. regards,
alant

Oh, I thing I haven't fully understand yet. The Matisse Rectifying board (when not connected to the M7 output stage board) yields an output voltage of 309V DC. Now, this is an "Open Circuit", right?

So, if I want the "True" measurement, I should connect the M7 output stage board to this Rectifying board, plug in the 12AX7 TUBES and then measure the voltage at B1+ and B2+ to see if they are 280V DC and 260V DC respectively.

Am I correct? Don't want to blow the whole thing up ....

CAT

Dear alant,

I don't mind at all. I come here to learn and any advice is welcomed.

Yes, I am in that school. If your son happened to be in 1E, 3E, 5A, 6A or 7A, I am his teacher then. If your son is not is any of these classes, then your son is VERY LUCKY ... ha..ha.

CAT

Dear CAT sir,

Please don’t mind as I just add some remarks. (我只是過路一提，請不要介意) It is a basic electronics that: Under no loading condition, it is just an open circuit. The voltage measured is the input voltage. For this reason, you should mention the voltage measured with respect to no loading, half loading or full loading conditions, etc... Then, Accphoto may understand correctly.
In summary, there are two kinds of method to step down high DC voltage to low DC voltage:
1) Without using IC (not constant DC output):
=> The simplest method is use resistor. But, with different loading, the voltage drop in the resistor is different which causes variable DC output.
2) With using IC (constant DC output):
=> Using voltage regulator or IC (integrated circuit) and called DC to DC converter which exists both linear and switch mode. It can provide constant DC output. But, select low noise IC for audio device. There are thousand of topologies in DC-DC converter design. Just few references at
=> video lecture at http://www.youtube.com/watch?v=WMi-ZN3qtSs&feature=user
=> http://www.powerdesigners.com/InfoWeb/design_center/articles/DC-DC/converter.shtm
=> http://www.maxim-ic.com.cn/appnotes.cfm/appnote_number/2031/
=> http://en.wikipedia.org/wiki/DC_to_DC_converter
=> Photo as below. Today’s DC to DC converter is very compact, like a IC chip. Applications include notebook computer, mobile phone, ipod, etc... For Hi Fi audio device, I never try!

You may continue this topic with Accphoto as he is a practical guy in here. Lastly, may I ask you a question: Are your boss called “Brother Thomas Favier” after seeing your email address and your principal subject is Economics? He is school supervisor of my son. If yes, I know who you are.


B. regards,
alant

Yes, got to measure the voltage with loading, otherwise the voltage is not right. Besides, the resistor between b1 and b2 should be 4.7K, not 47K.

Dear Accphoto,

Thanks for your help. I forgot to mention that the measurement was taken WITHOUT loading. If that is the case, should it be okay?

My Physics colleague told me that I may as well take a measurement with the loading as well. He said with loading, the voltage should drop significantly.

CAT

If input 310V AC, then output will be 310V x 1.4 = 430V DC and 309V DC seemed but the range that adjusted by the power broad should be more than 15V. There may be something wrong with the borad. Look for whether the diode position is correct or whether LM317 is working or not. By the way, did you measure the voltage with loading ?

Dear Accphoto,

The AC voltage from the Power Supply is 310V AC. After rectification, it becomes 309V DC.

I turned the adjustment knob (potentiometer?) on the Matisse board already. 309V DC is the MINIMUM I can get. If I turn it the other way round, it gives 325V DC.

Would you mind leaving your contact number at my email achan@sjc.edu.hk? There is something I still don't quite understand.... sorry.

CAT

You should direct wire from the power supply broad to B1 for left and right channel.
You should able to turn the Matisse Broad, what AC voltage you are inputing ? You can't  use the 1M to reduce the voltage.

Dear Accphoto,

I went there yesterday but I missed that part. Ah Tong Hing said I can use a 47K resistor to step down the 280V to 260V for B2+.

Yet, when I check the output from the Matisse Retifying Board, its DC out is 310V!! I think I need a 1M to step it down to 280V DC ....

Attached is the Schematics for the LITE M7 board. I "think" I have to direct a wire (underneath the board) from LEFT B1+ to RIGHT B1+ ... same for B2+ as well. Am I right?

I do not know the Lite Broad, why do you ask Master 棠？ He should know about the Board.

Dear Accphoto,

Another thing I find really strange about this M7 board. One EACH side of the board, there is a B+ 280V and another B+ 260V. From the Schematics, it suggests supplying power to BOTH and uses the GND as B-.

If that is for ONE channel, that means I have to have FOUR 280V (two will step down to 260)??

BTW, I changed the Caps to Jensen already (Power Supply)  :wink:

CAT

Good, I will go for the Jensen later on.

One thing I don't get it. If you look at the PCB of the M7 I just got, there are TWO B+ Power (280V & 260V) but there is NO B- ....

Should I use the GND to act as the B-?

CAT

Jensen or BHC but I perfer the sound of Jensen.

Dear Accphoto,

I totally agree. I have thought of using Black Gate ... but I GUESS the price will be sky high. Any other good suggestion on these two?

For Icefireman,

I got everything from Sound Explorer this time.

CAT

I buy it a year ago, the broad should cost about $100, ^-^, it should be quite a easy one as all resistor and caps are all stated in the Broad. I can tell you how the material and value affect the caps. It comes with a power supply board but i suggest you to use some others one.

Where did you buy the Marantz 7 broad?  I am quite interested in it.  How much is it?  Do you have any worksheet for making this Marantz broad?  Because I am very fresh on it.

Icefireman

Jensen Caps, @^@, No wonder it cost you 4K but it is worth every single cents.
I still have a Marantz 7 Broad, Any one interested ??? YOU can get the Board first build the power supply yourself.   I think you spent 3K, you will still get a decent sound using Auricap and Holoco or RMG resistor.  

CAT, better change the caps in the matisse broad too as it is really important and affect the sound.  Two output caps 47U 500V should also change to decent one as they have really big effect on the sound.

About the Jensen caps, you bought them from My3c.net or in Hong Kong?  Thanks for your info, I will take a look first.  If I have question, Ileave message here.

Icefireman

Dear Icefireman,

Yes, I live in Hong Kong as well. I oredered the My3c.net M7 from their website. It is just an okay product; depends on how much you want to spend and your other components.

The following photos are the parts for my new M7.

CAT

Yea, I am living in Hong Kong.  I am just planning my next target.  Because I just finished my UCD180.  Need a pre-amp later.  So that's why I want to get more info.  Are you living in Hong Kong too, Alfcat?

Icefireman

Dear Icefireman,

The one I got from www.my3c.net is NOT the best around. I think HiFiFever got a much better version of the Marantz 7. The price may be a bit higher but it also depends on the caps and other stuffs you use.

I am now building another one based on the LITE Marantz 7 board. This time I use:

Two cases: small one for power supply, large one for M7
One LITE transformer
Rectification stage using Matisse design (transistors type), not tube
All Jensen caps on M7
Cardas RCA sockets
NO volume switch as I got one
ALL RMG resistors

The whole thing cost around HK$ 4,500 or less.

Where are you located? Hong Kong?

CAT

To accphoto and alfcat,

You mentioned before that M7 cost around HK$3k (not include case and tube).  What components are included in it such as switch, colume control (which type), etc?   Is it used auricap and Elna?  Is it hard to solder all the things by myself?  Thank you.

Icefireman

[quote:90f23bdba0="WINDWSS"]no source of cheap choke in malaysia at this moment..

i'm think instead of choke can i just use the inductor 10mH?

maybe use 1 C-RC follow by 1 CLC....[/quote]

bro u try to find at FARNELL location at Subang Jaya.

http://my.farnell.com/inductors-chokes-coils

No problem, i like to read mandarine/chinese. Sorry for inconvenient as i do not has software to key in chinese word.

By the way may i know your your voltage measurement on the position below during idle:

1) voltage before the 50K resistor
2) voltage after the 50k resistor (on the plate)
3) wht's teh value of capacitor (uf) at the chatode
4) voltage at chatode

謝謝你對我的信任，我英文不好，還是說用中文回復你吧，我用的是原廠的電路，屏極電阻是50K（兩個100K 2W電阻並聯），陰極電阻是470歐，輸出端是2微法（MKP）＋0.1微法（油浸）＋0.01微法（油浸）電容組合，聲音我還是很滿意的，聲音比較有活力和彈性，M7的優點是中頻，聽LP，FM，卡座估計會很合適的，但是高低頻略有欠缺。當然也可以通過調整耦合電容值的大小來進行補償。

云外天,

The tube preamp i made is same as your post 5687单管胆前级 in your web but i change the 1M to 470k.

plate resistor audionote using 50k, vt4 using 10k.

do u know what is the effect of th eplate resistor and the cathode resistor?
i understand that by using higher plate resistor can get better dynamic, how about cathode resistor and cathode capacitance? how's the value will affect the sound?


Do u think a DIY marantz M7 is much better than this 5687?

M7的DIY文章又整理了9篇，大家可以參考下。

http://yunwt.u111.net/2wz2.html

Hi,
attached is the 5687 tube pream/buffer i made.

Using the attached schematic but some changes
1) use only 4.7k plate resistor
2) B+ = 175v
3) chatode resistor =470R
4) SOLID STATE half wave rectifier
5) 1uF cap
6) C-R-C filter

next will make another 1 using
1) ~250v B+
2) 10K plate resitor
3) choke
4) 0.47uF mundorf ZN
5) separe box for power supply
hopefully sound will be much better

Hi, Accphoto,

Can i have your email so that easier for me to contact you. Thne i can make arrangement with you to buy the choke....

thank you.

One famous local manufacturer selling choke of 10H 100ma , for only $80 (about USd 10.00), Sound ok but of course not up to those japanese one like tango or tamura.

I know someone tried to use inductor but its effect is weak when compare to choke. I can help you to buy one or two .

no source of cheap choke in malaysia at this moment..

i'm think instead of choke can i just use the inductor 10mH?

maybe use 1 C-RC follow by 1 CLC....

ka ka ka....... yes , I mean choke.... instead of coke......ka ka ka....

Dear Accphoto,

I think you mean "CHOKE", ha..ha... caught your mis-typing.

I agree with you, CLC should be better than CRC. But need to reserve room for the choke. It will be easier if DIY as we fix the dimensions ourselves. But if doing modification, depends on whether the case got room for a good choke, right?

CAT

Oh I see, thanks.

CRC = Capacitor + Resistor + Capacitor
CLC = Capactior + Coke + Capacitor

Ways to reduce ripples in power supply.

Hi all C Hing,

Would like to know what is CRC and CLC.

130V is too low. I suggest you to increase the plate voltage to 200v and use the orignal value of resistor. You will find the ' 動態" is much better. For power supply, it is better to use CLC rather than CRC and you will find the noise is much lower when you use CLC. About 10 H coke will be better and cost very low ( about $ 100 if you buy local).