Paul Carmody C-Note Modification Help

[audiojerry]

I just joined techtalk and am looking for help/advice on converting the C-Note MT configuration to a C-Note 2.5 TMM config similar to Paul's Classix 2.5. I've been impressed with the speaker buiding skills displayed by members of this forum.

I am so thrilled by the performance of the C-Note MT kit from P.E that I'd like to try putting it into a TMM floor stander. I was so pleased by the C-Note I followed it up by building Paul's Overnight Sensations, which I am also planning to convert to Paul's Overnight TMM. In their current MT boxes, each has impressive credentials: the C-Note with its neutrality and the Sensations with its amazing bass performance for such pocket sized speakers. Both kits were so inexpensive to begin with, it would cost only a little more to convert them. I've got the MDF and the tools needed including a compact router to cut the small recessed openings for the drivers.

I was hoping for advice on modifications that would be required for the C-Note TMM, and thoughts on changes to difficulty driving them. I have a 35 wpc PrimaLuna Dialogue Premium tube amp and Dialogue Premium preamp. The had no trouble pumping out impressive sound and deep bass to the MT versions. I paid close attention to assembling solid cabinets with cleanly soldered xovers, ofc copper wire, and appropriate damping.

[Wolf]

Since the C-Note is from one of PE's in-house designers and not Paul or anyone else here for that matter, it is highly unlikely that one of us will just reengineer a xover for such a project.

Later,
Wolf

[audiojerry]

My Bad. I thought it was one of Paul's. Sorry.

[davidB]

Try the C-Note MTM center.

[audiojerry]

Try the C-Note MTM center.

Thanks davidB. Would the TMM configuration require a different xover than the MTM?

[tom_s]

The main PE site seems to be down right now. That may be why no one has answered your question.

[LOUT]

Thanks davidB. Would the TMM configuration require a different xover than the MTM?

A TMM would probably benefit from a 2.5way style crossover (where the lower, farther-from-tweeter woofer handles less of the mids while the upper woofer handles more) while the MTM version allows both woofers to be right next to the tweeter where a simpler 2way crossover should be fine.

I'd expect the MTM crossover to generally be a better choice than nothing for the TMM though....though I'm also wondering if the MTM crossover has BaffleStepCompenstion or not because I think I've seen a pattern where many MTM designs skip the BSC assuming the speaker will be basically wall-mounted for hometheater use. Not sure. I'll try to give it a quick look and see how the MTM version sims.
Just a heads up, I'm NOT one of the experts here or anything like that. I simply have more free time than some of the busier members here, so I can run through the easier things like this, lol.


EDIT: Interesting...it looks like the Cnote MTM has a larger amount of BaffleStepComp than the MT version by about 3db. I'm guessing this is because the MT was trading a little bass output for slightly louder overall volume, and maybe the expectation that the little MT's would likely be set on a desk or something where less BSC was needed?


Here's a 2.5way XO that follows the MTM's frequency response very closely. I'm not sure if that's the best FR to follow though because the baffle-step response will be somewhat different for a TMM compared to the MTM. But the TM and MTM versions are already pretty similar apart from the MTM's 3db boost in the low-mids and bass, so it might end up pretty close either way.

Messing around with the shunt-to-ground resistor and capacitor values on the woofers can probably get a better response than what I've gotten so far.


The left is the above 2.5way simulated response. The right is the MTM 2way simulated response. (Both without BSC or Zoffset):


Not sure if this is worth persuing or not. I'd suggest waiting to see what more experienced members say first.
I think this has the lower woofer about -10db down by the crossover point.

[audiojerry]

Wow, that's a really thorough reply! Much appreciated.

I am very enthused about taking on the challenge knowing it will really help to fill my Covid-related stay-at-home free time. I'm wondering how the MTM placed vertically will differ in sound from the intended horizontal design. I am really liking the neutrality of the MT version, and it really works well with my tube amp and surprisingly with my son's vintage 15wpc Fisher Model 173, but am hoping for a bit more bass punch and a bit more output.

I noticed that your comment came at 12:08 amj. Are you on US time? - LOL

[LOUT]

I'd expect the vertical MTM to sound the same except the vertical placement should help its sound stay more consistant when you move sidetoside or have multiple people sitting around and listening.
The horizontal/short+wide placement will normally have wide vertical response (which doesn't do much good unless you can fly) while its horizontal response will usually have a notch somewhere around 2-3Khz (wherever the XO point is) as you move farther off-axis toward either side.
Rotating the MTM speakers to sit up vertically (tall and narrow) makes that notch/lobing happen as you move farther up or down from center....which is difficult to do by more than a few degrees unless you lay down or stand really close to the speaker at waist height.

The MTM version looks like it should have a subtle but noticeable bass increase around +3db compared to the upper response, and it should also have more headroom with the pair of woofers letting you turn your amplifier up louder where the TM's single woofer would start to struggle (I think the TM's start to struggle above ~25watts when playing deep bass).
With an amp that outputs more at 4ohm than it does at 8ohm, or an amp that's capable of more than 25watt peaks I think you'll get a nice little volume boost from the MTM.

[audiojerry]

I'd expect the vertical MTM to sound the same except the vertical placement should help its sound stay more consistant when you move sidetoside or have multiple people sitting around and listening.
The horizontal/short+wide placement will normally have wide vertical response (which doesn't do much good unless you can fly) while its horizontal response will usually have a notch somewhere around 2-3Khz (wherever the XO point is) as you move farther off-axis toward either side.
Rotating the MTM speakers to sit up vertically (tall and narrow) makes that notch/lobing happen as you move farther up or down from center....which is difficult to do by more than a few degrees unless you lay down or stand really close to the speaker at waist height.

The MTM version looks like it should have a subtle but noticeable bass increase around +3db compared to the upper response, and it should also have more headroom with the pair of woofers letting you turn your amplifier up louder where the TM's single woofer would start to struggle (I think the TM's start to struggle above ~25watts when playing deep bass). With an amp that outputs more at 4ohm than it does at 8ohm, or an amp that's capable of more than 25watt peaks I think you'll get a nice little volume boost from the MTM.

You have just motivated me to build it as MTM. But first I will be modifying my MT version of Paul's Overnight Success to his TMM plan, and then I will compare the results to the MTM version of the C-Note.
This will be fun. If you are interested, I will let you know how they turn out. If by chance you are near Brookfield, Wisconsin, I would enjoy your in-person comparison.

Thanks for the great help!

[LOUT]

I'm think the Cnote can reach about 10-15hz deeper and have around +5db more headroom compared to the OS (either TM vs TM or MTM vs TMM), but I haven't heard either in person so I'm curious to hear how they compare in real life in your words.

[audiojerry]

Amazingly, the OS MT has a more visceral, deeper sounding bass, but it falls a little short on neutrality. The OS sounds great with well recorded material, but can be a little bright at times. Both the OS MT and CN MT play to satisfying loud levels with no noticeable congestion using my 35 wpc tube amp listening in the nearfield with speakers 5 feet from my ears. They both create a very wide and deep soundstage in that setup. That's my impression where my frame of reference is my vintage 103db sensitive Klipsch LaScalas. I was pretty shocked when I heard what those little monitors can do, and I've owned plenty of very pricey high-end monitors in the past.

[djg]

Forum member Carbon13 did a lovely OSTMM build. The Cnote MTM ad page has a review of a customer that built three Cnote MTMs for his HT, with pictures. He seemed happy.

http://techtalk.parts-express.com/fo...-tmm-5-1-build

[Millstonemike]

Just so you know, a C-note TMM will be a 4 ohm speaker. Make sure your amp can handle 4 ohms.

[audiojerry]

Forum member Carbon13 did a lovely OSTMM build. The Cnote MTM ad page has a review of a customer that built three Cnote MTMs for his HT, with pictures. He seemed happy.

Thanks, Carbon13 did some beautiful work. I don't have have his woodworking skills or patience, but I will be trying to make sure all joints are tight and sealed, all solder joints are clean, and cabinet fill is proportional. I'm using ofc copper for all connections and high quality inductors, caps, and resistors.

Just so you know, a C-note TMM will be a 4 ohm speaker. Make sure your amp can handle 4 ohms.

Thanks for the caution. I have a slight concern, but I took into consideration that it dips close to 4 ohms only briefly, and I'm relying on over 80 lbs. of iron tranformers in my tube amplification to meet the challenge. (fingers crossed)

[LOUT]

It looks like the PrimaLuna Dialogue tube amp specs say it'll handle 4ohm and 8ohm speakers. I couldn't find a 15wattX2 Fisher 173 paper though.