Yasnyi Sokol

The final mesh size is about 1 mm. This was selected after comparing different meshes. I didn't try foam, only soft tissue around the hole, which I didn't like, and also it did not look cool

Hi, Finally, I made few records, which could probably give an impression how the modified speakers do sound... It is dificult to record speakers at home, but at least something than nothing. Mics are Rode M5 stereo pair, see www.rode.com/download/m5-mp_manual.pdf https://www.dropbox.com/s/6n2pqctf27dl4cv/Elvis_From%2024_96%20played%20as%2044100_16.wav?dl=0 https://www.dropbox.com/s/enl41vb92d8idht/Carmen_from_LP_to_44100__recorded%20as%2048000.wav?dl=0 https://www.dropbox.com/s/4668ui2t4agiu0r/Rimsky-Korsakov_from_192_played%20as44100_recorded%20as%2048000.wav?dl=0 Each mic was placed 80-90 cm from each speaker, and at the same height from floor (roughly at the middle between the horn and the top LF driver). Such position reduces slightly bass and midbass, but eliminates the room effect.

The latest version of schematic is in post#34.

Hi, all, InVeNtOr, thank You for the information. Actually I saw Your upgrage before i started, also there must be a video somewhere on Youtube about plastic horn modification. My friend used to do that and he thinks this is a must be for RF7 plastic horn. As for myself i am so happy with the result that don't want to change anything already. I guess one can make better speakers, but that will be another story. We tryed these speakers with rather good equipment: i.e. Lavry gold Dac. My interest is now digital source, and i replaced my old Weiss Minerva 1394 board based dac (updated with 1853 chip, blackgate caps etc) with simple TDA NOS 14 bit 1540 selfmade dac and like it very much. Will play soon around 1541 just to compare with 1540. These black caps on the photo are all BG FK type and that really makes sense to the sound. Good luck to everybody, hope someone would follow my modification to RF7 some day!

Hi, all, Some recent updates. I stay with this crossover for a long time already and want to say i like it. But if someone decide to repeat my modification I would strongly recommend Mundorf silver oil caps on the high pass of the scheme (8.2 and 15 uf). I have compared both and found SIO much and much better. These are really true high end caps and i could not expect how much they outperform regular Mundorf Supremes!! Regular supremes are the waste of money compared to SIO. Less resolution, less dynamic. Yes, they are detailed, but that is not that details which come from the real resolution. Also regular supremes add some touch i felt always with them. SIO must be trained for about 200 hours to break in. I used a simple scheme with amplifier and load resistor to cook them. I also compared SiO s to not known widely Rike Audio S-caps. These caps are very open and transperant. Very impressive, too. Even more dynamic than Mundorf silver oils. But they add some coloration. Overall, Mundorf SIO give more balanced and deep presentation, so i left SIO caps. Probably, Rikes could be used for bass or mids very well.

Hoping the project is finished. The box is hand made: plywood 10 mm and natural oak 1.5 mm.

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I think the 3rd order is still better than my 1st order. So fix it for a while as follows. Tweeter has the mesh #20 instead of original.

Now i am back to 3rd order to make comparisons. Look at this size

Placing the horn close to wall could unbalance the responce. Only bass notes will be amplified by "big horn". Look at that: The same applies to Jensen corner horn with Altec 416 driver: My friend has built the last one and here are his measuments in real room (which is also quite small). His room has more complex wall behind the speakers than one used in the simulation, which might be also the reason why the plots differ. http://photo.qip.ru/users/yras/4142238/101865539/#mainImageLink http://photo.qip.ru/users/yras/4142238/100875270/#mainImageLink

Continue the story. I compared two meshes on compression driver, #20 and #40 (the number of holes per inch), and found #20 sounds better for me. Mundorf silver/gold/oil 2.2uf caps have arrived. At the moment the crossover is as follows. 2.4uf cap is 2.2 uf mundorf silver/gold/oil plus 0.22 uf tin foil multicap RTX. All other caps are Mundorf supreme. All coils are Jantzen wax coils.All resistors are jantzen MOX super resolution.

Perhaps, Your could find interesting to read my small research on rf7 crossovers here https://community.klipsch.com/index.php?/topic/156444-klipsch-rf7-old-version-crossover-modification/

That could make some possitive effect, thank You for the idea. Meanwhile I am waiting for my best caps from Mundorf, let's play with enclosure of RF7. Bass Reflex or Back Loaded Horn? TypicalT/S parameters (they are published) are as follows: Fs =31 Qes=0.22 Qms=11 https://community.klipsch.com/index.php?/topic/24048-diy-project-k-1089-av-rf-7-copper-woofer/ These make one think why they use bass reflex enclosure for the drivers? It looks like the drivers are more suitable for horn load. I put parameters of bass drivers in 3D acoustical simulator (3D Acoustic Research project I take part in, the last version of software is not published yet). The idea behind that program is to solve the wave equation in 3D domain for given electrical and mechanical parameters of the drivers. For simplicity I use single driver with same parameters (double Vas and Sd, half Re). For acceleration CUDA is used with powerful graphic card. The element size of numerical grid is 1 cm. Equivalent parameters Re =3.02 ohm Sd =0.0720 sq.m Fs=31 Vas=212 l Qes=0.22 Qms=11 Here are some results. The BR is tuned to around 43-44 Hz similar to real speaker of Klipsch. Black point shows the mic position. Open space Here the baffle-step effect is presented, and also the enclosure is too big for given Qts. This next plot is real impedance measument of two woofers in parallel (the simulation doesn't take into account the losses due to dampening material inside the volume, that's why impedance peaks are smaller). Also I have the second peak close to 60 Hz instead of 70 Hz (i didn't measure T/S parameters for my own drivers, just took the data above from the given link). Half space (on the floor) Floor and ceiling Close to wall A lot of bass. But ...do You like this? Penal room (all reflecting walls except the rear to the listerner which is open, or in other words, perfect wave absorption behind the listerner. In this particular case it makes big reverberation time and low absorption in bass region as follows from the plot) (in the last case the real energy level in bass region would be determined by the amount of energy absorption in real room) One consideration from that is: the driver placed too high above the floor generally lacks from the midbass region due to reflection from the floor. This effect is reduced when the mic is far to the speaker. Carpet is better than rigid floor surface. The last picture shows the effect still remains in real room. Partially also due to low Qts of the driver. I guess that engineers of Klipsch tryed to get most possible low bass with the bigest possible volume of the enclosure. Compare that with real measurements of RF7 which were published in my first posts. The next consideration is to replace BR with BLH. Horn has big exit area along vertical, and reflection from the floor from numerious point sources at the exit is partially compensated. This improves midbass region. Floor acts as a part of the horn. On the other hand, bass horn is difficult to build, the exit area is always a compromise as it is less than the wavelength, and the reflection of back wave inside the horn produces ripples, which are reduced for half space radiation, quarter space etc. A lot of literature on that. BLH is also tricky as one should take into account both frontal radiation from the driver and from the horn with time delay. Here is an example of BLH for RF7 drivers (two in one enclosure). Quite simple as it consists of almost plain elements. Back loaded horn (width is about 45 cm, height 1 m, depth about 40cm) on the floor. Lets "listen" By this i mean that I can calculate FIR (finite impulse resosponse) at the mic position. I take a test wav file, split it into LF and HF parts (HF is original minus LF obtained with a digital filter, Hamming window function is used for filtering with -42 dB outside the main frequency region). Then the LF part is convolved with FIR from 3D simulation. The result is summed with original untouched HF part, taking into account the volume level of both. So, bass comes from the enclosure, while HF is "sonically ideal". This can be considered as I "did nothing to real wood work but still is able to listen" to the result The comparison is here (two WAV files). LF is filtered at 800Hz. TIme shift between LF and HF is zero. (When crossed at at 250-300 Hz the delay 3-5 ms for HF to compensate the group time delay of bass section sounds better). http://mab.to/ZFvb7liIs Forgive some sibilants (they come from numerical simulation). Bass reflex has typical sound of bass reflex, the horn has typical "tabouret bass". .

I think that most unpleasant peak comes from the dust cap. Damping the basket wouldn't help it much. Some resonances across the woofer may go away, of course.

Agree with that. The second problem of 3 kHz peaks is that they come from two point sources separated with the distance of 28 cm (two LF drivers). 28 cm is a wavelength at 1.2 kHz, while 3 kHz is already almost two wavelengths. So the vertical angle phase interference is very irregular, next plots show the sum of two woofers and the tweeter in Leap at 1 m distance, at the middle between the top woofer and the tweeter. Original Klipsch crossover These speakers are a lot of compromises . I expect that reducing this unwanted energy at 3 kHz from two woofers also improves the directivity patern. Considering the design with 1 cap and main notch filter on the tweeter resonance one can also easily add the second cap after the notch. It would be already 3rd order of course, but with main notch filter outside of working region. These is calculated for the tweeter without the mesh. It doesn't differ much from the "1 cap-version", but at low end the tweeter is filtered more. At the moment I put stainless steel mesh with 1mm cell on the compression driver, think it sounds quite well with 1 cap cross, but haven't measured it yet.