RCF Art300A

[J M Fahey]

Sorry but clicking rcf_art300a_sch.pdf yields nothing.
Is this the Forum glitch you were referring to?
If so, please reupload.
Thanks.

[skint]

Hello. Just to update.As I could not find any problem and I have very limited knowledge, I sent the two monitors to the music shop where bought from so they could compare them side by side. I received them back today with a note that they could not find anything wrong with capacitors or anything else.(I had told them to be sure to check the suggestions that everyone on this forum so kindly contributed to) To be honest,I don't think they know that much apart from replacing complete new panels
They replaced the volume pot which alow needed,made no difference to the volume problem is still there with one monitor.
What I do notice that when both monitors are set for line/micro the volume is equal on both speakers.It is only on music and voice settings on the small control panel that the difference is obvious.This is the setting used with mixer.
I hope I have not bored anyone with reply. I wish I was near some people on this forum who really knows their job and sort out my problem. Once again I thank everyone who contributed

[Jazz P Bass]

Just to clarify the issue that you are having: the schematic clearly shows a 'cut' in the signal amplitude when either the "Voice" or the "Music" switches are engaged.
Do both monitors respond to the switches in the same manner?(ie: a cut in the loudness)
What happens if the switches are left open?

[skint]

Hi.Jazz P Bass. Thank you. Yes both monitors respond to the switches in the same way,I usually use the music setting as I play keyboards through them but sometimes I use them for pa + keyboards in fairly small venues
The voice setting add slightly more bass to the sound,the music setting adds more middle and the line in drastically increases the volume when used with a mixer.
If line in switch is engaged,both monitors are equal volume but I don't think this setting is recommended for use with mixer.I think it would be used for plugging a mic directly into the monitor as background hiss becomes louder if volume would be at more than 1/3 up.
If either music or voice (or all switches out) one monitor is much lower volume than the other. For example,I was playing at a fairly small venue last night and set one monitor at exactly half volume and I had to turn the other one completely full up for both speakers to be equal using the music or voice setting. I hope you can understand my explanation. Thank you.

[J M Fahey]

Yes both monitors respond to the switches in the same way,

This simply is not true, told by yourself:
1)

If line in switch is engaged,both monitors are equal volume

2)

If either music or voice (or all switches out) one monitor is much lower volume than the other.

You can not call that "responding the same way".

Also your description is the opposite of what both the brochure and schematic say, I think you "understand" your switches backward.

You say:

The voice setting add slightly more bass to the sound,

while it actually adds a broadband peak around 3 KHz, which is reasonable if they want to improve intelligibility.

Also:

the music setting adds more middle

No, it adds almost 10dB both at 100Hz and around 10KHz, being deep bass and "high" highs, the exact opposite.

Also:

the line in drastically increases the volume

No, the *Mic* in raises the volume, which is to be expected.
It would also explain the increase in hiss you notice.

Dear JPBass: both switches provide boost, because they act on the negative feedback side.
By the way, the amp brochure says exactly the same.
www.studiognomo.it/pdf/rcfart300a.pdf

EDIT: in a nutshell, the proper way to use those switches is:
1) line/mic set to Line, if driven by a mixer (your case).
2) Voice switch off, you equalize from the mixer as needed.
I think the Voice setting is when you plug a microphone straight into the speaker, and want *some* EQ control.
3) Music switch usually off, monitor Flat, you equalize from the DJ or PA mixer.
I think (may be mistaken, of course) that the Music setting, with its deep bass boost (considering what this compact cabinet can reproduce) and high treble boost makes it more "DJ friendly".
The problem is that you actually *lose* headroom, because you are forcing the speaker to reproduce Bass which, because of its ultracompact size, it can not do on its own.

I have tested and used many similar compact plastic speakers, including RCF , JBL, you name it.
None of them produced the bass you might have expected out of a very high quality woofer driven by a good loud power amp.
You always need to add some subwoofer to the mix.
"Sub" meaning in this case anything below 100 Hz.
Which is not surprising, the World may be crumbling down, but Physics Laws remain true.

[skint]

Thank you for describing. When I say both monitors respond in the same way to the switches,I mean that the sound variation works the same with the switches, on both speakers (mic setting more middle,music setting some more bass and highs)but one speaker is much lower volume with the volume control set the same on both speakers.
I apologize for describing the switches the wrong way.
Also,bottom switch is marked line/micro
The line/micro switch. If this is set to line as suggested,there is a big variation in volume in both speakers,regardless of what position the voice or music switches are at. The only way both speakers are equal volume is when micros witch is pressed in,but this setting causes background hiss if volume is any more than 1/3 up.
I hope to have described the fault

[J M Fahey]

Ok, now we're talking.
To find a problem the best is to change just one thing at a time and see what happens, then continue with others, doing the same on and on.
And you must describe what *that* action did, the best way possible.
When you mention 2 things at the same time, we can't know which of them was the culprit.

Ok, so we must start with some setting where both speakers have the same gain or volume (for now it doesn't matter whether you get *now* the sound you like, that comes later), and then push/pull switches , one at a time, same in both monitors, which of course will change something.
We want to find one action which does different things in both.
We are looking for a difference, not yet for the best sound.

regardless of what position the voice or music switches are at.

OK, leave them wherever you like it best, but the same setting in both.

The line/micro switch. If this is set to line as suggested,there is a big variation in volume in both speakers

OK, *now* we found a difference.
If this switch is "off", "out", it's outside the circuit, and gain is minimum , signal enters through R12 and R15, which by the way, "live" in the circuit and are "always there", no matter what the switch does, so it is the "off/line/less gain" setting which should be the same on both.
Even unsoldering and pulling the switch out , should not affect Line setting, so the "low gain" setting is the one which should be the same in both.
**Only** way it's not is that in the "sick" monitor either R12 or R15 are open (very unlikely) or have cracked solder or some track connecting them is cracked open.
Being a balanced input, losing *one* side would probably halve gain.
If the switch is "On/MIC/Higher gain", then each half bypasses/shorts R12 and R15 respectively.
The fact that now (although with excessive gain) both monitors respond the same, confirms the diagnostic of R12 or R15 or their connection being open.
Go check it.

EDIT: I had clipped and enhanced a small part of the schematic and pasted it here.
Somehow, it "didn't stick".
Since I see JPBass succeeded in reattaching the full schematic (thanks ), I'll try again with my snippet.
Wish me luck

[Jazz P Bass]

Mackie RCF ART300A Schematic

Here is the schematic for those of you who want to follow along at home.

[skint]

Thank you very much JM. I have checked what you suggested and closely examined for any breaks in the tracks, but everything looks ok.
To try to help you,I removed the small panels (with switches and input/output) from both speakers and interchanged them.The result was that this made no difference.
The monitor that was sounding low volume still was low and the other good one was at its normal level,so I was assuming that maybe the problem seems to lie somewhere in the main board.
Also.Even though the (faulty)monitors volume is less than the other good one,the sound is still clear from it with no distortion or rattles from the tweeter or main speaker when volume is turned up.

[Jazz P Bass]

I kind of thought that you stated that before (swapping input boards).
There are two separate power amps.
One for the high & one for the low frequencies.
Can you tell if both are losing volume?
I hate to say it but without proper equipment to test this you are not going to get this repaired over the Internet.

[J M Fahey]

Ok, I think we are still running this race.
The schematic does not show any connector , yet you mention one.
Please download the input schematic section I enhanced and , using any Graphics program, even Paint or something, draw a dot line separating what belongs in the small plugin board and what remains on the larger PCB.
If the line zigzags, so be it.
If there is some kind of connector, number the pins and label it as "Male" and Female" .
Then repost it here.
A closeup picture may help too.

[g1]

There is some kind of communication problem here. If swapping the input boards makes no difference, then the problem in the bad monitor must exist at all settings of the input switches (if volume controls are set the same).

Edit: Perhaps if only the switches and jacks are on the input board, and the actual circuitry is elsewhere? Is this what you were thinking JM? The upper right of the page 1 schem. looks like a connector so I would think page 1 is the input board but perhaps not.

Some photo's of the input board may be helpful.

[J M Fahey]

It's just a gut feeling/hunch/experience/all of the above
Don't want to overguess or extrapolate way too much, so I'll wait for the answer.
But I think you think what I think

[skint]

Photos

It's just a gut feeling/hunch/experience/all of the above
Don't want to overguess or extrapolate way too much, so I'll wait for the answer.
But I think you think what I think

Hi I attach photos of control panel and main board (some with transformer removed

[g1]

The line/micro switch. If this is set to line as suggested,there is a big variation in volume in both speakers,regardless of what position the voice or music switches are at.

This is opposite of what you originally stated. You said you swapped the control boards and it made no difference.
You must clear this up before any progress can be made.
Try both control boards in your good working monitor. All switches (music, voice, and line/micro) in OUT position. Is there a difference between the 2 control boards when connected to the good monitor?