Upgrading Marantz 7C capacitors

Dear Accphoto and brothers,

My friend now gets hold of my Marantz 7C. He is wondering whether he can make the BASS better by replacing the capacitors.

As Accphoto pointed out once I can upgrade the 0.01uf cap. But in the KIT I got, there is NO 0.01uf cap at all as it is not cater for LP / Phono.

Dear Accphoto, by making us of the photos I posted, can you suggest me how to upgrade the caps for my friend?

Link to the photo: http://www.hififever.com/forum/viewtopic.php?t=1725

CAT

Dear Accphoto,

Thank you so much for your help.

I have attached the schematics for this Marantz 7C. Please take a look and give me some of your valuable advice.

This time, I am doing it for my colleague. He said he is willing to spend around HK$ 2K or so for the capacitors. So please advise him on what BRAND of caps he can use as well.

Once again, thank you very much!

CAT

Dear Accphoto,

I forgot to attach the file .. ha..ha..

Dear Koifarm,

I haven't seen this Clarity Cap before. The Marantz 7 is in the hands of my colleague now. He wants to buy it from me but asked me to help him solve the problem of "loosey" base. He wants more SOLID bass.

Where can I get Clarity Cap? Are they expensive?

Merry Christmas to you!

CAT

Dear Accphoto,

Thanks for your valuable advice.

There is nothing I can do with the Voltage, right?

I will follow your advice and change the components once I got the Marantz 7 back.

Thank you and Merry Christmas to you.

CAT

Sorry Koifarm,

The Marantz 7C is using Mullard 12AX7 tubes. Blackburn, '60s and closely matched.

CAT

Dear Accphoto,

Thanks for the advice. I wise 10 years from now, I could be as good as you are ... ha..ha...

For the time being, we can only stick to KITs .... and learn by trial & error.

I took your advice and changed the Caps inside the Matisse to Auricap. Indeed, they sound VERY different. The Matisse now is much much better and natural. Just run it for around 5 hours and both me and my wife are very satisfied.

Enclosed is the photo of the Matisse after changing to Auricaps.

CAT

Dear Accphoto,

Should I suggest my colleague to upgrade the Marantz 7C power supply caps to BlackGate if he is willing to pay?

CAT

Then I can only suggest him to change the capacitors as you have suggested (and increase the uf of some of those as well).

What is the use of adding the 3.3K resistors between B+ and R2?

CAT

Dear Koifarm,

I registered at the Clarity Cap website. However, I am unable to order items. They just don't have a button that says "Add to Cart".

I can see my shopping cart; just can't get things into it ... :cry:

CAT

Dear Koifarm,

No wonder. I will try by first dropping them an email.

Thanks for the info.

CAT

Dear Accuphoto,

I would like to take my FIRST trial by changing the C3 capacitor to 3uf for my colleague.

BTW, just need to change C3, no need for C11 which is sitting at the opposite. (Silly Q from people who doesn't know about electronics)

What brand would you suggest? Jensen? Auricap? or Moundorf?

CAT

Dear Accuphoto,

Thank God I take a last minute look at the forum. And thanks for your post right IN time .... I was just going to leave for Mongkok.

I will purchase the items as you described and see how it goes. Will give you a feedback by tomorrow night

Thanks again.

CAT

Dear Accphoto & Koifarm,

I changed all the caps of the Marantz 7C as the first trial. However, the Marantz 7 had been gone for too long and I can't exactly recall HOW it sound.

After upgrading, I "think" it gets closer to the Matisse but the Matisse seems to be a bit better. Unfortunately, my colleague is tooooo eager to get it back and I haven't got the chance to really compare the two.

I also changed the Volume switch as he doesn't like the Ladder one and I installed a TKD selector for him as well.

CAT

Dear Accphoto,

Thanks for your help along the way  

My colleague is now using the Marantz 7C but he said the Auricaps haven't yet run in. The sound is a bit dull for the time being.

I also changed some capacitors of my Antique Sound Lab amplifier. Will post the photos here later for sharing. However, the improvement is NOT good as expected. Maybe you can give me some advice as well.

CAT

Dear Viewer,

Long time no see la ... wish you the best for 2008.

I went to Po Shu right before New Year. They don't have the ALPS Black Beauty anymore. The old man said it had been sold out for some time.

On the contrary, I picked up TWO rolls of 100m hook up wire from them. They are from RS; should be pretty good wires. Only $ 110 each roll.

CAT

Dear Accphoto & Viewer,

What do you think about the "ladder" volume I DIYed? Assuming that there is NO cold soldering, is that a good one? For this type of Ladder Volume control, what makes it good? The design? The materials? I got the thing from DIY zone.

The problem with that Ladder volume control is, it is step by step. Turn to step 4 is too low the volume, turn to step 5 it is too loud .... There are 24 steps, I never use more than 5 .... just don't know what is the use of the rest ....

CAT

Dear Accphoto,

The one I DIYed has 4 layers. Two Rin and Two Rg. That means the signal will go through TWO resistors for each channel, right?

So if I increase the Ohm value of the resistors, the sound will be lowered. Am I correct? If my logic is right, I should have the value (ohms) of the steps narrowed if I want small increment steps by steps.

You are very helpful ... many thanks.

CAT

Dear Accphoto,

I see. I will try to get some DALE resistors and change the values of probably third to six / seven stages.

The one from DIYzone has small holes. I think it is not very possible to use RMG resistors as their leads are quite thick.

Still waiting for the Matisse and the ASL amp to get to their Normal stage after changing the caps.

Too busy helping my daughter to prepare for her exam yesterday and no chance to post neither photos or schematics of the amp. Really would like to seek your advice on whether I replaced the right materials inside the ASL amp.

CAT

Dear Accphoto,

I managed to get the Antique Sound Labs 6L6 Mono Block Schematics and post it here. Hope that you can give me some advice on upgrading it.

Following another link by an American, I upgraded TWO capacitors as indicated in the photo. The person used Moundorg Supreme Gold / Silver but I used Jensen same value 0.22uf / 650V. I also changed the other one to an Auricap as the original one is a bit cheap.

For resistors R5 & R6 (I guess), that person used DALE / Vishay but I used RMG with same value.

Do you think the modification makes sense?

CAT

Strange ... cannot upload the Schematics?

Converted it to JPEG and try again.

CAT

Dear WINDWSS,

As I have said before, the one I got from DIY got pretty small holes. I am not sure whether I can use RMG as their leads are pretty thick.

CAT

Dear Accphoto,

Thanks for your ultra fast response. I am not sure whether this is my 心理 problem or what ... the whole system does NOT sound as good as before after changing the caps.

I have thought of two possibilities: ONE, of course, is the capacitors need time to run in. I just run them in for 20 hours or less.

Second, a Mis-Match or need to upgrade some other components to match those newly installed.

I will seriously consider your suggestion and will enlarge the Schematics later today when I got home.

Many thanks.

CAT

Dear Viewer,

Can you post a photo showing the resistors you have changed?

I will see if I have time tonight and post my modified CD 33 with the DAC incorporated into it.

CAT

Dear friends,

I attached here a better schematics of the ASL AV-25. Hope this can help. I really would like to upgrade this Amp as I "think" this is a good amplifier at this price of HK$ 3K only.

CAT

Dear Viewer,

I didn't realise that I already posted the modified CD 33 with the DAC incorporated into it. I just made it a bit better by:

1. squeezed out some of the blue stuffs inside the cold / hot pad to make it thinner.

2. drilled a hole on the DAC PCB and installed a pole to stablize the board.

I have compared several songs with my CD 33 and the CD 88 unmodified. My CD 33 for sure sounds better than the CD 88.

CAT

Dear Viewer,

Where did you get the DALE resistors? I know that you can get 東京光音 from Mak's.

If you use RMG, it is going to cost you a lot of money I guess. How much it cost you this time?

CAT

Dear Accphoto,

Actually there is little story about this modification I am looking for. After I got this ASL AV 25, another user "Viewer" forwarded me a link from another forum in the States. That owner of the AV-25 said the sound quality of the AV 25 can actually be improved by a few simple modifications. Unfortunately, when I send him a message, he said he already SOLD the AV 25 and can't recall about the modification.

I then sent another message to ASL, they replied saying that changing the Signal Path Resistor and the Capacitors will do the job.

1. If you need more details , then change the resistor on the signal path,
2. If you need more smooth sound, change the electric caps and perhaps add a choke will improveit
3. If you need a different sound, change the C3,4 cap into some other type will improve it.

And that is exactly what you are telling me here.

What I want to know more are:

1. Change the Resistor on the Signal path = change the VALUE of the resistors or change the BRAND to a better one?

2. For an idiot like me, which resistors are they referring to? R5? R6? R13?

For me, I would like to add more details / clarity to the system and hopefully just a little more bass.

And finally, if you have time ... can you explain a bit why changing the resistors will improve the details?

Many thanks.  

CAT

Dear Accphoto,

I agree with you that using different materials will yield different sound effects. However, if the circuit is poorly designed, using better materials will just give opposite results --- magnifying the errors.

So far I have been running the 6L6 and the Matisse each and every day for 3 hours / day. The results of changing the capacitors are getting more obvious now. As I asked my wife and my girl how do they feel about certain piece of music, they like it more tho' they don't in the past.

In the past, I don't believe that a "good" power supply is that important. Now, I am a believer. I think a good power supply / source is even more significant for Tubes Amps and Players, am I right?

I still got a funny problem with my CD ... sigh ... The Left Channel is significantly louder than the Right channel. What could have gone wrong? I checked my soldering points, they are all okay. And the difference is pretty obvious ...

CAT

Dear Accphoto,

If I would like to learn circuit designs, should I therefore learn about how amplifiers are constructed? Should it be the simplest type to start off with?

CAT

Dear KKWAN,

Yes, I have tried that before. Actually I have 3 sets of 396A tubes. I marked them and swapped them once in a while, using different combinations. Still the output on the Right Channel is still lower.

BTW, your remote works okay or not?

CAT

Dear KKwan,

That is really interesting. Maybe there is a poor soldering point or so in your CD's PCB. I tested it out a number of times, inter-changing it with my remote on TWO different CD 33. It worked all evening.

I don't have the Marantz 7C anymore. I sold it to my colleague and I changed the WIMA caps to Auricaps, changed the ladder type volume control to Alps for him as well.

Under Accphoto's advice, I changed the Matisse caps to Auricaps as well. After around 40 hours of running in, the Matisse sounds much much better than before. The base is more solid and the sound is "thicker" than before. Also, it is not that "fast" (Hi Fi sense). As I listen to female vocals relatively more, the ladies sound "sweeter".

I connect the modified CD 33 to the Matisse and then to the Antique Sound Lab AV25 Mono Blocks. I changed two capacitors and some resistors in the AV25 as well. More details and better base now I have.

The speakers are just Chinese clone ProAc 1SC. Low price (HK$ 2200) resting on a beautiful but not heavy pair of stands. My next modification will be the cross-over and alike of the speakers.

CAT

Dear Accphoto,

In the past, I should be called an "Arts" student as well. However, some of my classmates in my class were constructing amplifiers even at the age of 15. They eventually went overseas and became engineers.

I am doing self - study as well. Actually I also learned a lot of stuffs through this method; computers, cats raising, aquatic plantation, etc. Nice to see people going through the same route.

Sorry to bother you but I will have another question to ask you later this week. It is about an EL34 Mono Block amp I am doing for my colleague. I followed all the procedures carefully but when I turn the amp on, one capacitor (known as C12 -- 47uf/63V) explodes. This happends for BOTH mono block but I couldn't figure out why.

The schematics had already been scanned (this time should be able to read clearly, ha..ha). I will take some photos as well. Hopefully you can help to show me some hint or help me to solve the problem.

Thanks in advance.

CAT