How many WIMA films can you stuff on a Tone Board?

[USMC Spike]

I like to replace any electrolytic capacitors in the direct audio signal path with film types. What the 'direct audio signal path' is exactly is up for debate.Tom

Hi Tom, Skywatcher, Everyman,
for those of us who might not know how to ID the
parts in the direct signal path, which of the following would we Identify and replace?

Then, which parts would provide for feedback. I know this is two different things.

I'll post a partial schematic and call out parts. Please let us know, which are correct, maybe, and missed the boat?

Here is the schematic of the P700 Phono Assy/board.



Typically, the standard is "parts along the bold line are 'signal.'"
Capacitors:
Only one "direct" connection is C713.

2nd connections:
C701, C702 Base connections.

Feedback connections:
C714, C715
C705, C706
C707, C708

Is there a priority for the following?
C711, C712
C709, C710
C703, C704

Would it be the same for resistors?
R701, R702
R703, R704
R706, R707

Feedback Resistors:
R728, R729
R716, R717
R718, R719
R733, R732

Then balancing:
R710, R711
R712, R713
R714, R715
R720, R721
R730, R731

That's enough for now gentlemen.

 

[USMC Spike]

In order of most distortion to least distortion:
Tantalum caps
Polar electrolytics
Bi-, Non-polar electrolytics
Film caps

 

[Steven Tate]

Isn't the bold line ground? I would think the AC signal went through many of those components above and below the bold line.

 

[JJCalvillo]

I thought the signal path was indicated by the little loops around the path. In USMC Spike's example at J701/703. In this case the two channels are mirrored on the top and bottom of the schematic, and the transistors would be amplifying the signal?

 

[Steven Tate]

I thought the signal path was indicated by the little loops around the path. In USMC Spike's example at J701/703.

The loops represent shielded cable. The line through the loops should be where the signal enters the board.

 

[JJCalvillo]

The loops represent shielded cable. The line through the loops should be where the signal enters the board.

Think we're saying the same thing.

 

[leesonic]

WIMAs are always good. As a general rule of thumb, I usually replace any electrolytics 10uF or less in the signal path with them.

 

[JJCalvillo]

So when are the guys who know what their talking about going stop laughing at the electronically challenged and chime in?

 

[USMC Spike]

It's ok to be electronically challenged...you just don't want to remain there.

Here is a review for Everyman. Of course, I need the review also,
lest I forget; and at my mature age, forgetting isn't quite the norm--YET.

If you already know this, no worries, some of us might find it helpful.

In general, the incoming signal is on the base, and exits via the emitter.
Vcc comes through the collector, but if it has a resistor in series with the collector,
depending on which side of the resistor feeds back to the base,
you have either:
Collector feedback bias
Emitter feedback bias
Maybe I can draw a pic...better to find a site and link.

This isn't very simple but you get the idea: LINK

I'll find a textbook instead and I'll find a pic and upload it.
Here is a pic of them from Floyd's electronic devices text (p255):




















Floyd, T,L. (2012.) electronic devices: electron flow version, 9th ed. Pearson
Education, Inc., publishing as Prentice, Hall, Upper Saddle River, New Jersey. U.S.A.

 

[PooPoo]

 

[ocdecio]

4070 tone board

 

[pioneervibes]

All power circuits get electros, except 4.7uf and under and only when there is little current to worry about. The 10uf you used are probably sufficient for where they are since they were small electros to begin with.

Debating whether to replace my 4.7uF 25V with electrolytic or film. Options are:

- UPW1V4R7MDD (35V, $0.32ea)
- MKS2C044701M00KO00 (63V, $1.75ea)

I've selected 63V MKS2 film caps for all my others 3.3uF and below. Now just debating if worth it to include 4.7uF as I do have space would just sit off the board a little bit.

 

[Lavane]

If they will fit, why not? I've seen tube amplifiers built with all film caps, no electrolytics. Power supply included. Many were HUGE!

 

[HPMguy]

Film caps work great it tube equipment, it's hard to make electrolytics that withstand 400V. They get large though....

 

[ocdecio]

Debating whether to replace my 4.7uF 25V with electrolytic or film. Options are:

- UPW1V4R7MDD (35V, $0.32ea)
- MKS2C044701M00KO00 (63V, $1.75ea)

I've selected 63V MKS2 film caps for all my others 3.3uF and below. Now just debating if worth it to include 4.7uF as I do have space would just sit off the board a little bit.

I've been using strictly audio grade electrolytics to replace existing electrolytics. My preference is Elna Silmics but since they are going end of life I choose UKAs. The sound quality is noticeably better, bright but not strident. At least for me it works better. And they fit better too.

 

[p4spooky]

UKAs work great, also UKLs in my opinion.

 

[Steven Tate]

One advantage of films is their longevity. In sections like preamps, it seems worthwhile to consider longevity since there are so many low capacitance caps. But I don't argue with those who hear differences. At 72, my hearing has no finesse to it, and I doubt I would ever hear a difference in components.

 

[Lavane]

Film caps work great it tube equipment, it's hard to make electrolytics that withstand 400V. They get large though....

I use 450v and 500v electrolytics a lot. Even where 400v caps were used originally.

 

[Lavane]

4070 tone board


View attachment 2307931

In cases like this where there are a lot of them cramped together, I'll mount some of them on the back side of the board as long as there is room.

 

[ocdecio]

In cases like this where there are a lot of them cramped together, I'll mount some of them on the back side of the board as long as there is room.

There is absolutely no extra space in the 4070 Super extra packed.