想開始整Marantz7 (PA-1)pre-amp, 但有問題想問

恭喜發財! 今年長做長有!!
本人想今年DIY一部Marantz 7 pre-amp.  但知識有限.
現想問一題好簡單問題:
一部pre-amp內,分別由幾多主要部份組成?
謝謝

一部pre-amp內,分別由幾多主要部份組成?

1. Chassics (Case)
2. Power supply, include Rectifier, fuse, switch, etc)
3. Input socket (I/O)
4. Wiring
5. input selector (if you need)
6. Volume control
7. Pre amp unit (PCB based or wire wrap)
8. Output socket
9. Protection circuit (Power on/off pop sound protection)
10. A good grounding method.
11. Misc items, (Foot, vol knob, Text, power cable, etc)

my budget is around 4k without chassis.  So which combination is situable for my budget? any suggestion.  (Since I don't have time to take the hififever pre-amp class, so i have to do it by myself)

1. Chassics (Case)
    may buy one at hififever

2. Power supply, include Rectifier, fuse, switch, etc)
    I know hififever is selling this part, but i wanna know power supply is important for the whle pre-amp or not? some are expensive.

3. Input socket (I/O)
    you mean the RCA input part?

4. Wiring
    figure it out later

5. input selector (if you need)
    No need. pair in and pair out, that's it.

6. Volume control
    級進式音量VR and 東京光音VR, what are the differences?  And what's the meaning 10kA and 100kA or 250kA?  Which choice is good for beginner to install?  

7. Pre amp unit (PCB based or wire wrap)
    I already have a Marantz 7 PCB from accphoto.  Wiring will be figured out later.

8. Output socket
    Should be RCA output

9. Protection circuit (Power on/off pop sound protection)
   Any sugguestion, I think I need to buy one

10. A good grounding method.
     I may ask kk if I have chance to ask him

11. Misc items, (Foot, vol knob, Text, power cable, etc)
     Not a big problem atm

Thank you whom may answer these stupid questions.

Dear Icefireman,

You can expect the followings:

1. Chasis -- HK$ 600 should give you a pretty good chasis. However, you may have to buy the KNOBS separately if you want good quality ones. Average is around $ 40 each. ON / OFF + Volume = $ 80.

2. Power Supply -- a very nice one is just around $ 300.

3. If you already got the PCB (I think you have the Marantz 7), getting the components can cost you a fortune. Resistors are cheaper; DALE is good at a reasonable price. Next come HOLCO and then RMG. DALE is just a few dollars a piece. Holco can go up to $ 1x / piece. RMG can be over $ 20. Capacitors are more expensive. WIMA is cheap but not very tube like. Jensens are good at a much higher price. Depends on your TASTE and your budge to choose your capacitors.

4. Sockets --- Cardas and some others can be very expensive. CMC sockets are good choices at reasonable price (<$100 pair). You need two pairs, one in and one out.

5. I won't suggest using 東京光音 Volume. If you want Cheap Volume switch, you can use ALPS; just around $ 50 or so. Ladder type (good ones) are much better but at a very high price. Mine is over $ 800.

6. Grounding is always challenging. Better have someone to guide you around and you need to do some testing. Different people have different grounding preference.

7. Wiring -- don't let power cables to sit next to signal cables. Wiring method is important too to avoid interference.

If you need further details, drop me an email at alfchan@netvigator.com with your mobile phone number. It is much easier to talk over the phone.
Don't publish your number here.

CAT

CAT Sir,

Thank you for your help.  I have started to diy the pre-amp.  But I have another problem which is the chassis.  Since the M7 PCB is quite large, there is no such size chassis (I need 430mm wide one) in the diy shop in MK.  So do you have any source which I can buy the chassis.  I know there are some online shops in China to sell the chassis.  Do you have any reliable shop can be refered?  Thank you.

Icefireman

Which PCB you are using ...... ?  I may have a spare casing which may fit you !

Accphoto,

I am using the M7 PCB which you sold to me half year ago.  The dimension of the PCB is 17.5 X 21cm.  It is quite large so that I need to use the bigger case which must be 43cm wide one.  Do you have that size spare case in your stock?  Thank you

Another question:
Is Aluminium case good for connect the ground wire?

I have one more question about the switch (on/off).  Should I add delay on it in order to aviod the "bop" sound?  Thank you.

Normally, you should switch on the pre-amp first and then the power-amp. You should also switch off the power amp first and then the pre-amp. Adding a delay should provide some sort of protection if you forget to do the above procedure. The delay should be a pcb with a small ic (nE55) and a relay which switch the signal to gound  in the first 20 second when power on, then open after. It should be available in alot DIY and should cost you no more $ 100 .

[quote:9d815a2b1e="icefireman"]Accphoto,

I am using the M7 PCB which you sold to me half year ago.  The dimension of the PCB is 17.5 X 21cm.  It is quite large so that I need to use the bigger case which must be 43cm wide one.  Do you have that size spare case in your stock?  Thank you

Another question:
Is Aluminium case good for connect the ground wire?[/quote]

Aluminum case of course will better than iron case in term of sound improvement. That PCB need a big case like this one...., They are available in Hong Kong but expensive. Order direct from China will properly save some......

Dear Icefireman,

Accphoto has provided you with very useful information. I still have one of these boards left which uses LM555CN chip set. If you want it, I can give it to you. I think I assembled it myself last year. Check the photo.

I tend not to use this type of board but follow closely the procedure mentioned by Accphoto; turn on the Pre-amp, wait 20 seconds or so and then the Power Amp. When you shut down the system, just do the reverse.

BTW, I have dis-assembled my set of M7 and will re-construct it again (since it is no longer beautiful after so many modifications). Will share with you the photos later.

For the time being, I will have to stick onto my Pass 1.7.... ha..ha. :wink:

[quote:f15d7dbd28="icefireman"]Accphoto,

I am using the M7 PCB which you sold to me half year ago.  The dimension of the PCB is 17.5 X 21cm.  It is quite large so that I need to use the bigger case which must be 43cm wide one.  Do you have that size spare case in your stock?  Thank you

Another question:
Is Aluminium case good for connect the ground wire?[/quote]

Dear icefireman,

You can try searching in 麥X in 女人街鴻光商場，I noticed there are some tube amp cases available.

Andy

Thank you all the brothers' info.  About the case, I have ordered an Aluminum case in China.  It was R$520 (I tried to show the case later).  

About the switch, I have to thank Alcat and Accphoto.  Both gave me alot of info.  Finally, I decided to add a 0.1uf cap between the switch (L).  And I would pick the simple action was turning on pre-amp and then turn on power amp 20s later.

One more question is about the fuse.  I should hook up L -> fuse -> switch -> transformer or N -> fuse -> transformer?

That is the Alumium case

Where did you get this case? Seems to be good wor.

[quote:91840b1c75="icefireman"]Thank you all the brothers' info.  About the case, I have ordered an Aluminum case in China.  It was R$520 (I tried to show the case later).  

About the switch, I have to thank Alcat and Accphoto.  Both gave me alot of info.  Finally, I decided to add a 0.1uf cap between the switch (L).  And I would pick the simple action was turning on pre-amp and then turn on power amp 20s later.

One more question is about the fuse.  I should hook up L -> fuse -> switch -> transformer or N -> fuse -> transformer?[/quote]

Dear icefireman,

Always connect in this way: L -> fuse -> switch -> transformer

A better way is to use a 2-pole switch like this:
L -> fuse -> switch -> transformer L
N ----------> switch -> transformer N
and you need two capacitors if you use 2-pole switch.

Andy

Cat Sir,

Do you want to know the source of the case? if so, pm me

A better way is to use a 2-pole switch like this:
L -> fuse -> switch -> transformer L
N ----------> switch -> transformer N
and you need two capacitors if you use 2-pole switch.

1) Why using 2-pole switch is better than single?
2) Where should I put the two capacitors (退火电容)? (On switch, between L and L, an d, between N and N)  And which value of capacitors should I put? (such as 0.1uF / 250V 陶瓷电容)

Icefireman,

Please check your email. Thank you.

CAT

you should use 0.01 uf  1kv better, or min 630V, using 250V will blow your transformer easily.  Two pole switch is slightly better because it will isolate the transformer completely in case, you reserve the phase.

I should put one capacitor only between L and L.  Or do I need to put 2 capacitors on L and N separately?  Thank you

Hi icefireman,

You need 2 of them if you are using a 2-pole switch.

Andy

Normally, I will put one between the switch on L & L and one between L & N , this will reduce the spark on both L & N  and whether you use one-pole or two-pole is not really matter.

Dear Accphoto,

Do you think you have time to put up a diagram or so.

I think that explains much better since I have no idea what a 2-pole switch as well... ha..ha..

:wink:

Try this one.... The cap on the switch is on L.

I have drawn a circuit diagram of my M7 pre-amp.  I stilll have 2 questions.  

First, about the second cap which I put on the switch, the first cap is attached to C and D.  How should I attach for the second cap at switch?

Second, about the grounding, is there any problem if I ground the wire like the diagram I drew?  

Thank you.

Icefireman,

Did you take a look at my diagram under the other thread?

"Re-wiring the Marantz 7"

I have tried something close to yours in the past ... still not as good as the one I am using

CAT

There are my parts for my M7

I would suggest you putting the boards in different locations before actually drilling the holes.

I made a stupid move and was too rushed to put down the boards. The wires gone un-necessarily long and the performance is not as good as expected

Do you understand the diagram I posted?

do you mean that all the GND wires (includes RCA out and in, VR GND) attached to the PCB board?  Only the Earth wire from plug goes to ground to chassis.  But I don't know which one is PCB GND.  Any clue?  Thank you.

Please take a look on picture.  Is it the point to attach the chassis?  

Oh, I forget to ask one more question.  
The 12.6V on 穩壓 has (+ve) and (-ve), but I could not find the (+ve) and (-ve) on M7 PCB side. Do I need to find out which one is (+ve) on PCB?

Thank you

Cat Sir,

You meant the revised circuit like this diagram?

Dear Icefireman,

I am not an expert here but I would try the following arrangement. See if this is better.

You said you can't find the +ve and the -ve for the 12.6V on the PCB. I think the 12.6V should be for the 12AX7; if so, it doesn't matter. You can connect either to the filament, there is no polarity. However, make sure you ground the 12AX7 -ve.

Hope this helps.

[quote:d181aad14c="icefireman"]Please take a look on picture.  Is it the point to attach the chassis?  

Oh, I forget to ask one more question.  
The 12.6V on 穩壓 has (+ve) and (-ve), but I could not find the (+ve) and (-ve) on M7 PCB side. Do I need to find out which one is (+ve) on PCB?

Thank you[/quote]

12.6V is for Heater 燈絲 there should be  a connection for Heater on 4.5 of the tube.

[quote:831816728c="icefireman"]I have drawn a circuit diagram of my M7 pre-amp.  I stilll have 2 questions.  

First, about the second cap which I put on the switch, the first cap is attached to C and D.  How should I attach for the second cap at switch?

Second, about the grounding, is there any problem if I ground the wire like the diagram I drew?  

Thank you.[/quote]

Connect the second cap to A & D. this will help to reduce pop sound...

Already hook up the switch!

Icefireman,

Your rectifying board is the same as mine ... ha.ha

Cart Sir,

Big problem is coming.  All the items had been hooked up.  When I connected to my amp, the big noise was coming out from the speakers.  Even I did not turn up the volumn.  Did I do something wrong?  Please give me some advices.  Thank you.

I think you have to post us some updated photos before we can give you comments on it.

CAT

Thank you every CHING.  Finally, my M7 pre-amp had been finished.  But the signal problem is fixed by Sound Explorer.  They found out my PCB had shorting somewhere.  

It is just started to run in.  I will report the result later.

My setup is

DIY M7 pre-amp
DIY UCD180 amp
Klipsch Heresy II speakers

icefireman

Oh, glad to hear that you finally got the M7 running.

Funny to say that my Marantz 7 got "problem" as well. Two days ago, I sent photos to Sound Explorer and asked them if I can further improve my M7. Brother Tong said I have used WRONG values for my capacitors ... ha.ha..

I asked him what can I do then? He suggested me swapping some of the capacitors and get some new.

Just finished doing everything this afternoon. "WOW" -- is what I would say about this upgrade. The female vocals sound MUCH MUCH better; the sound stage is more open and the bass is much improved as well. Still need to run in the BIG 2.2uf at the rear ...... see how they go by then.


CAT

There are 2 updated photos

My UCD180 is used 8 x Nichicon 10000u 63V capacitors.  What's the difference if I replace them by 2 Jensen 15000u 63V for each channel.  Thank you.

或者我應該問:

現在我的UCD180後級用8xNichicon 10000u capacitors, M7 pre-amp 是用Auricap.  我應該儲錢先換掉後級的cap 抑或 M7 cap呢 (換上Jensen)?  換邊一part會有明顯的升級 (或更好音質)? 謝各CHing

8 x Nichicon 10000u 63V capacitors. What's the difference if I replace them by 2 Jensen 15000u 63V

=============================================

icefireman,

8 x 10000 = 80,000uf
2 x 15000 = 30,000uf ONLY. Assume this is for ONE channel, still got a total of just 60,000uf.  

Any reason for reducing the capacitance? Only if you know the effect of reducing / replacing the caps, I would rather NOT use Jensen as an "experimental tool" as they are not cheap at all.

CAT