Low-Cost PMC-inspired TL Monitor with DC130A and DC28F

[xrk971]

Oops, I meant cut C2 by half - so about 2.2uF to 2.5uF.

 

[aditya]

What if we use https://www.parts-express.com/Peerless-BC25TG15-04-1-Silk-Dome-Tweeter-264-1040

what do you feel looking at the specs. I know it’s probably a apple to orange.

 

[xrk971]

The specs look good but it’s 4ohm tweeter. If you want to use the passive XO I developed, you need to use the same (or very similar) driver. Similar in impedance, sensitivity, fs, Vas, and Qts. And even then it won’t be perfect because crossovers are designed for a specific driver in a specific baffle and spacing between the drivers.

 

[aditya]

Yes but the RSF28 was is also a 4 ohm so I was wonder if it could be a temporary replacement but I guess we can’t do I will wait for rs one to be in stock in india

 

[xrk971]

Sorry I am mixing things up. The RS28F and RST28F are both 4ohms. Probably compatible with the Peerless you mentioned. As long as you use this crossover from this thread:

 

[jmascreen]

It looks like aluminum cone since the XO diagram says RS180-8.
That’s an awesome driver - I use it in this speaker:
View attachment 1022286
View attachment 1022287
This would not be a bad speaker to make into a TL.

I have done umpteen measurement and still getting humps and dips around 2kh with RS180-8 in PMC clone, how do you get this flat till 3.5KH? I cant go above 2KH

 

[xrk971]

Here is what I got with the RS180 at 3.5kHz crossover.

you need to measure at 0.5m and place on a stand so it’s well off the ground. Adjust the electrical crossover to sort of coincide with natural falloff and you get a steeper slope.

 

[jmascreen]

Here is what I got with the RS180 at 3.5kHz crossover.
View attachment 1074626
you need to measure at 0.5m and place on a stand so it’s well off the ground. Adjust the electrical crossover to sort of coincide with natural falloff and you get a steeper slope.

This is what I get, I had measured at 1m at middle point between woofer and tweeter.

 

[xrk971]

What does your raw woofer measurement look like? The bumps and dips are probably room interactions and floor bounce. That is why it is important to measure at 0.5m and have speaker on a tall stand so floor bounce is not picked up.

 

[jmascreen]

What does your raw woofer measurement look like? The bumps and dips are probably room interactions and floor bounce. That is why it is important to measure at 0.5m and have speaker on a tall stand so floor bounce is not picked up.

This is how it looks like.. I am keeping it on normal speaker stands, What is the ideal height to keep the speakers?

 

[xrk971]

That’s really lumpy. Is this mounted in the TL? Ideal height for measurement is at least twice the mic distance or circa 40in. Sometimes the TL has features but it is closer to 300Hz to 500Hz.

 

[jmascreen]

That’s really lumpy. Is this mounted in the TL? Ideal height for measurement is at least twice the mic distance or circa 40in. Sometimes the TL has features but it is closer to 300Hz to 500Hz.

Yes its mounted in TL. Let me try measuring at 1m and keeping the mic at .5m

 

[jmascreen]

Yes its mounted in TL. Let me try measuring at 1m and keeping the mic at .5m

Do you stuff it before measuring?

 

[xrk971]

Yes, very important.

 

[jmascreen]

Took a new measurement with mic at .5m and with double height. The hump has reduced but the dips are still there also Is the enclosure over stuffed?

 

[wae]

This looks like room reflections and as you changed the distance of the mic it DID NOT change the 800 & 1600 spike which backs that up. Your initial post #208 looks like 800 & 1600 Hz peaks.
Measurement outside with some damping on the floor?

 

[jmascreen]

This looks like room reflections and as you changed the distance of the mic it DID NOT change the 800 & 1600 spike which backs that up. Your initial post #208 looks like 800 & 1600 Hz peaks.
Measurement outside with some damping on the floor?

This is in room response with no damping, I will paste one soon with little damping

 

[jmascreen]

@xrk971 look what I have got here.. Oh damn this is more low ends than what I made with RS180-8 need to reevaluate that one. Thanks for making such a wonderful design.

 

[xrk971]

Congrats on the new speaker build. Looks like you are getting the benefits of the TL in full force.

 

[xrk971]

Hi Jmascreen,
Do you have some more photos of the build of your speakers showing how you did the j get al TL channels etc? The speakers look great. Also, a shot showing the details of the front baffle. Did you recess the driver plate on the tweeter and woofer? Also, are you using the passive XO or doing this actively?
Thanks,
X