mboxler Posted April 23, 2023 Share Posted April 23, 2023 22 minutes ago, SpeedLimit said: Yes .. but the Atlas sound is given to go up to 4500 Hz if i remember.. Sounds like we are in agreement. If the Atlas is only flat to 4500hz, and the AL3 tweeter filter has a steep 6000hz high pass, then there would be a hole in the 4500 to 6000hz range. Quote Link to comment Share on other sites More sharing options...
SpeedLimit Posted April 23, 2023 Author Share Posted April 23, 2023 Just now, mboxler said: Sounds like we are in agreement. If the Atlas is only flat to 4500hz, and the AL3 tweeter filter has a steep 6000hz high pass, then there would be a hole in the 4500 to 6000hz range. Yes, it seems to be that problem Quote Link to comment Share on other sites More sharing options...
SpeedLimit Posted April 23, 2023 Author Share Posted April 23, 2023 found on the web: Atlas Sound PD-5VH 40W Compression Driver Overview The 40W, 16 ohm Atlas Sound PD-5VH compression driver provides a powerful, intelligible, extended frequency response to large format horns. The 2" voice coil is machined to the optimum tolerances. Equipped with an Alnico V-DG magnet, the PD-5VH offers maximum temperature stability and optimizes output for yielding the lowest amplifier power requirements. The driver also provides terminals direct to the voice coil. The units are finished in gray, baked epoxy and mounts to large format horns that terminate in standard 1-3/8"-18 male coupling thread. Specifications: • Power rating: 40W @ 16 ohms • Plane wave frequency response: 110 - 4,100 Hz • Sensitivity: 110.7 • Impedance: 16 ohms • Voice coil: 2" • Dimensions: 5.125" H x 4.375" W. Highlights Powerful driver for large format horns to deliver powerful sound reproduction Extended frequency response to create the optimum intelligibility Great for indoor and outdoor use with environment resistant construction 1 Quote Link to comment Share on other sites More sharing options...
SpeedLimit Posted April 23, 2023 Author Share Posted April 23, 2023 Plane wave frequency response: 110 - 4,100 Hz Quote Link to comment Share on other sites More sharing options...
Deang Posted April 23, 2023 Share Posted April 23, 2023 4 hours ago, Frzninvt said: The AL-3 was designed with the K-55M midrange in mind. The K-55M runs about 1.5db hotter than the K-55V. Only the engineering samples were “hotter”. When the production samples showed up, they weren’t. Frequency response is not identical, but sensitivity is. A two port phase plug K-55-V was used to design the AK network. Compare AK to AK-3 (schematic). I roll AK-2 users back to the AK, since the low pass cap is the same, and the high pass section is the same as the AK-3. Use the AK, AK-3, AL-3, AB-2 with any 2 port phase plug variant, including John Allen’s driver. 1 Quote Link to comment Share on other sites More sharing options...
Deang Posted April 23, 2023 Share Posted April 23, 2023 4500Hz. Two primary reasons for that. Roy doesn’t believe a driver should have to do anything it wasn’t designed to do. The single port phase plug isn’t giving you 6kHz without the collapsing verticals of the K-400, and if you’ve seen the published response in the Dope from Hope, it’s pretty rough. The other reason is for a smoother power response, you want the polars at the crossover to match. Quote Link to comment Share on other sites More sharing options...
Deang Posted April 23, 2023 Share Posted April 23, 2023 16 minutes ago, mboxler said: Sounds like we are in agreement. If the Atlas is only flat to 4500hz, and the AL3 tweeter filter has a steep 6000hz high pass, then there would be a hole in the 4500 to 6000hz range. Yeah, but are you sure? Like really sure, lol. 1 Quote Link to comment Share on other sites More sharing options...
mboxler Posted April 23, 2023 Share Posted April 23, 2023 5 minutes ago, Deang said: Yeah, but are you sure? Like really sure, lol. I'm not sure what I had for breakfast this morning 🙄 1 Quote Link to comment Share on other sites More sharing options...
Bacek Posted April 24, 2023 Share Posted April 24, 2023 19 hours ago, Deang said: Only the engineering samples were “hotter”. If so then why T4A which has 1 dba higher dumping was used instead of the T2A autoformer? Quote Link to comment Share on other sites More sharing options...
Deang Posted April 24, 2023 Share Posted April 24, 2023 Tap 4 on the T2A is really -3.35dB. When you add the 5mH in parallel with K-55-M, applied attenuation of the T4A is virtually the same. Quote Link to comment Share on other sites More sharing options...
SpeedLimit Posted April 24, 2023 Author Share Posted April 24, 2023 4 hours ago, Bacek said: If so then why T4A which has 1 dba higher dumping was used instead of the T2A autoformer? it will be hard for me to find T4A autoformer .. Quote Link to comment Share on other sites More sharing options...
mboxler Posted April 24, 2023 Share Posted April 24, 2023 50 minutes ago, SpeedLimit said: it will be hard for me to find T4A autoformer .. I'm a little confused. Do you already have an AL-3 crossover? If so, it already has a T4A. 1 Quote Link to comment Share on other sites More sharing options...
SpeedLimit Posted April 24, 2023 Author Share Posted April 24, 2023 oh sorry, i didn't know that the autoformer of an AL-3 crossover is already a T4a 1 Quote Link to comment Share on other sites More sharing options...
Bacek Posted May 24, 2023 Share Posted May 24, 2023 On 4/24/2023 at 1:11 PM, Deang said: applied attenuation of the T4A is virtually the same. T2A is 3.35dB and T4A is 4dB. Close but I will not call it the same. Quote Link to comment Share on other sites More sharing options...
Deang Posted May 24, 2023 Share Posted May 24, 2023 It has been over a month. I don't recall what @mboxlerfound with the T4A. I would be surprised if it's 4dB exactly. There is also a 5mH inductor in parallel with the driver, so I have no idea what the actual attenuation is. Quote Link to comment Share on other sites More sharing options...
Bacek Posted May 24, 2023 Share Posted May 24, 2023 1 hour ago, Deang said: I would be surprised if it's 4dB exactly. At least from T4A data sheet and voltages there its 4dB (10V -> 6,31V), as opposed to T2A where it's labeled as "3" but voltages are 10V->6.8V which is 3.35 1 hour ago, Deang said: There is also a 5mH inductor in parallel with the driver, so I have no idea what the actual attenuation is. You are right if we are comparing AA vs AL-3. But if we are looking at AL-3 only and use of different transformers in same place then there will be difference anyway, cause both oh them will have this inductor applied. Only question is if this difference is insignificant or not. Some people swear to hear difference when it can't be measured and here it can be measured. 1 Quote Link to comment Share on other sites More sharing options...
mboxler Posted May 24, 2023 Share Posted May 24, 2023 2 hours ago, Deang said: It has been over a month. I don't recall what @mboxlerfound with the T4A. I would be surprised if it's 4dB exactly. There is also a 5mH inductor in parallel with the driver, so I have no idea what the actual attenuation is. I'm sure I have a T4A measurement somewhere, but I bet it's pretty close to -4db. Granted all of the above will result in a 2nd order high pass to the squawker, but it's the ratio of the 13uf capacitance and the autoformer inductance that dictates how high in frequency the steeper slope extends. Also, if one defines attenuation as the voltage difference between the input taps used and the output taps used, the inductance really changes nothing. That doesn't mean the inductance doesn't change the transfer function. Attached in the difference between a T4A (taps 3 -0) in parallel with a 5mh inductor and a T2A (taps 4 - 0) in parallel with a 5mh inductor. The resulting inductance for the T4A is 3mh. The resulting inductance for the T2A is 4mh. Notice the steeper slope of the T4A. But more interesting, notice at 580hz that even though the T4A attenuates the voltage by an extra .65db, the voltage across the K55 is actually higher. As frequency increases, - .65db difference comes back into play. If you were to use a 3.5mh parallel inductor with the T2A, the transfer function will be closer to the T4A/5mh combo, but the slight difference in the reflected impedance on the 13uf capacitor will change the curve some as well. Mike 2 Quote Link to comment Share on other sites More sharing options...
mboxler Posted May 24, 2023 Share Posted May 24, 2023 Hopefully the moderators will tolerate my "repurposing" of a T2A autoformer, 'cause here I go again... If you have a T2A and want to get really close to a T4A, here's a hack you can try. The steps involved are... Remove the common wire from squawker out negative. Attach squawker out negative to Tap 2 of the T2A. Add a 3.6mh inductor across Taps 2 and 5 of the T2A. The winding ratio between taps 0 -5 and taps 2 - 5 happens to be 64.2%, or -3.85db, pretty close to -4db. Mike 1 1 Quote Link to comment Share on other sites More sharing options...
Deang Posted May 24, 2023 Share Posted May 24, 2023 2 hours ago, mboxler said: -3.85db, pretty close to -4db. @Bacekwill give a D- for that one. 1 Quote Link to comment Share on other sites More sharing options...
Bacek Posted May 24, 2023 Share Posted May 24, 2023 Nice trick, for sure 3.85 is much closer then 3.35. From what I remember ear "resolution" is 0.3db So I would say B+ for a clever aproach Quote Link to comment Share on other sites More sharing options...
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