C-Note excursion

[JoeC]

My pic of the back side of the XO's on my work bench that I posted after I soldered the board shows two unused terminal points. That is where the .22 cap went. After I get them apart I'll get more pics.
With the new woofers I can hear or see no problems and everything sounds just fine. The woofers barley move. It's the old speakers that jump wildly back and fourth. Nobody has answered my question as to the issue that the spiders and surrounds can stretch out enough as to not hold the cone in it's place while playing music?
I would think if it were my reciever, the wiring or the XO's I would have the same problem with the new speakers also?

[davidB]

The .22 cap is to be in parallel with the coil, not before(in series).

[Kornbread]

And that is why I was trying to clarify that the speakers, before the woofers went screwy, did not sound like a tiny transistor radio, without the loudness button being pressed. You have to understand, online we cannot hear/see/feel/test/whatever, then you have to add the individual person into the equation ... everyone is different. Way different. This makes it difficult to diagnose an issue from afar. The audioscience review says the c-note has solid bass, so, if it sounded like a tiny transistor radio from the start w/o the loudness button, more than likely, something was amiss from the get-go. I wouldn't have thought it, but the sim also shows that 27 watts can drive the woofer past 5mm xmax below ~37hz, which, combined with the 'loudness' button, does indeed bring into question over-extension of woofer travel.

I see the silkscreen area marked NC (where the optional .22uf cap goes) on the ebay pcb add copy, but cannot distinguish where the pads/traces go after there. The .22uf cap should jump across L2. Surely, if someone took the time to layout/build a board, it is correct. Just crossing things off the list.

Same thing with checking dc offset of the amp, and phase reversal of a woofer. This happens. I've done it more than once! To be sure woofer phase is correct, you can touch (touch not hold) the posts of a small 1.5v battery to the speaker wires. The woofers should move the same direction in regards to battery connection. Again, just crossing things off the list.

Personally, I have not seen a surround, or spider, stretch enough not to hold the cone in place, although, I have seen surrounds get hard, and/or fall apart. With the cones 'jumping wildly back and forth' it sounds like the motor came apart, or the cone became detached from the motor? I have not seen any threads mentioning the dsa135 having a problem which would be indicative of a QC issue, but there is always that possibility.

[djg]

I'd like to know more about your MCS 3225. It looks to be pretty old. How long have you had it? Has it been in use continually or did you pull it out of retirement for this? Ever been serviced?

Also, rereading your first post, was the initial satisfactory performance of the C notes with or without the loudness control on? And, how loud do you listen to these? Apologies if you answered these questions earlier, I did sort of just skim the thread.

Basically, I'm asking if you abused the C notes with loud music with the loudness control on (which is meant to boost lows when the volume is set low) until they failed.

[tom_s]

Given the age of the MCS, you really need to check the DC offset to rule out slow-cooking the voice coils of your woofers. It looks like a schematic might be tough to find, so if you have more than 20mv of DC on the speaker terminals, you'll have to do a little sleuthing to see if there's a marked trimmer pot to adjust the offset. Some amps & receivers have adjustments for that and some don't. If it doesn't and it's a discreet output section (not an STK module) it probably uses matched pairs of transistors somewhere in the circuit. Some of those old transistors are notorious for aging poorly and can cause all kinds of problems.

[JoeC]

The loudness button is normally on unless I'm watching a tv program. (my pc has a pcie tv tuner installed)

DC Off Set:
Right side

Left side


With this test, I left the loudness button in the On position and the Subsonic Filter in the Off position.

[wogg]

Single digit millivolts... no DC offset. The mystery continues...

[LOUT]

Can you get the broken pair of woofers to move forward/backward a little just by shaking them while holding them (aka, are they SUPER loose)?
Or, do those broken woofers make a little noise (slight rattling or scraping) when you shake them?

[981CS]

I like the way this vintage receiver sounds, but I do have a Technics SA EX140 receiver rated at 100w per channel. I hooked it up and did try that with the new speakers to see if there was any difference. The MCS receiver sounds way better.

Well yeah, of course it does. That Technics is a "modern-ish" AV receiver and from the era of them over rating power specs. I've not heard a single AV receiver that sounds better 2 channel than most late 70's receivers.

The specific Technics I use is an SA-5160, circa 1976 (and 25WPC as I now look). It sounds fantastic with my Overnight Sensations, Pioneer BS22's, etc. But it just can not drive the CNotes. I hooked the CNotes up to several different 2-channel amps and found that they sounded better the more power they received.

I too listen to Jazz and such and the more powerful receivers brought instruments like the double bass more "up front" and realistic and with greater presence.

I also tried the Cnotes in my garage/workroom with a Dayton class D amp (rated at 50x2, so probably less) I have and they did not do well in that setting either.

[djg]

Do you always have the loudness on?

[djg]

Well, I guess carry on as before and see what happens. If you blow more woofers you'll know something's wrong. I'd still recommend a subwoofer, these are 5" 2 ways. If you had a sub, you wouldn't need the loudness on.

My PC system is a Dayton 8" 250 watt DSP sub, A Schiit USB DAC, and two Outlaw monoblocks. Several 2 way satellite pairs of various woofer sizes. I have never blown any speakers. In my setup, the DSP sub is after the DAC and before the amps. If you did this, there wouldn't be any low freqs sent to your receiver for the loudness control to boost. The sub is built to produce bass, you can turn it up as you wish.

[JoeC]

Well yeah, of course it does. That Technics is a "modern-ish" AV receiver and from the era of them over rating power specs. I've not heard a single AV receiver that sounds better 2 channel than most late 70's receivers.

The specific Technics I use is an SA-5160, circa 1976 (and 25WPC as I now look). It sounds fantastic with my Overnight Sensations, Pioneer BS22's, etc. But it just can not drive the CNotes. I hooked the CNotes up to several different 2-channel amps and found that they sounded better the more power they received.

I too listen to Jazz and such and the more powerful receivers brought instruments like the double bass more "up front" and realistic and with greater presence.

I also tried the Cnotes in my garage/workroom with a Dayton class D amp (rated at 50x2, so probably less) I have and they did not do well in that setting either.

I have a 25w vintage Scott receiver. When I first tried that receiver could not push the C-Notes either, and that was when the speakers were brand new. Took about 5 seconds to hear that a 25w receiver wasn't going to work.

Shook the old speakers around, nothing loose and not flopping around either. I can post a video with what it looks like playing music and compare what the new speaker does

[JoeC]

Well, I guess carry on as before and see what happens. If you blow more woofers you'll know something's wrong. I'd still recommend a subwoofer, these are 5" 2 ways. If you had a sub, you wouldn't need the loudness on.

My PC system is a Dayton 8" 250 watt DSP sub, A Schiit USB DAC, and two Outlaw monoblocks. Several 2 way satellite pairs of various woofer sizes. I have never blown any speakers. In my setup, the DSP sub is after the DAC and before the amps. If you did this, there wouldn't be any low freqs sent to your receiver for the loudness control to boost. The sub is built to produce bass, you can turn it up as you wish.

I only have a 2 channel receiver and I''m not going to buy an expensive sub to do that. My DAC (Topping D30) runs from my pc to the aux input on the receiver. I have 15" woofers in my living room, I already stated I do not have the luxury of space in this little office to place a powered subwoofer.
I'll carry on as before and just be aware of the limitations with the volume. If I do blow these speakers...that'll be it. I'm not going to put one more penny into this diy, I have already spent way too much for a "C-Note" I'll get something else off the shelf at a box store, I'm giving up on $$diy$$!

[djg]

That's too bad. It's a great hobby, not for everyone I guess.

Can get expensive.

[JoeC]

Can get expensive.

That kinda defeats the purpose of diy don't it?

[djg]

Not at all.

[Kornbread]

"About my system: running audio from my pc via usb to a Topping D30 DAC and connected a Modular Component Systems 3225 receiver rated at 27w per channel."

"I have a 25w vintage Scott receiver. When I first tried that receiver could not push the C-Notes either, and that was when the speakers were brand new. Took about 5 seconds to hear that a 25w receiver wasn't going to work."

Not all amps are made, or measured the same, but???

[981CS]

I only have a 2 channel receiver and I''m not going to buy an expensive sub to do that. My DAC (Topping D30) runs from my pc to the aux input on the receiver. I have 15" woofers in my living room, I already stated I do not have the luxury of space in this little office to place a powered subwoofer.
I'll carry on as before and just be aware of the limitations with the volume. If I do blow these speakers...that'll be it. I'm not going to put one more penny into this diy, I have already spent way too much for a "C-Note" I'll get something else off the shelf at a box store, I'm giving up on $$diy$$!

The more I listened to and messed around with the CNotes the more I found them to be somewhat of a conundrum in the since that they are relatively inexpensive and do sound decent (especially given their price), but they aren't for budget or low powered receivers and pairing them with a much nicer receiver seems like a bit of an odd thing to do as well.

They aren't tall, but more of a deep and squatty shape and make for difficult placement on a desktop. I much prefer my overnight sensations both for nearfield and due to the smaller size and the ability to sound good with only 25WPC.

Fun build though, but now I have no clue what to do with them as I have zero practical use for them.