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Hivi 3.1A DIY Speaker With Sehlin Mod Review

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I'm probably overthinking it, but I feel weird soldering stranded wire to a PCB. Would I be crazy to install some 2-position terminal blocks there instead? Would you concur the distance between the holes for the driver outputs is 7.5mm? I was thinking of grabbing a few of these:

https://www.mouser.com/ProductDetail/Phoenix-Contact/1731022/?qs=sGAEpiMZZMvPvGwLNS6718PaoTt7FM7cTG%2BvBorjbNc=

All the quick connect-style male connectors I've looked at expect two holes for each tab, and I would be asking for trouble if I tried to drill holes in this PCB.
I went ahead and soldered the wire to the board. It felt ok.
 

Music1969

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Hi all @Mudjock

What are the actual crossover points (Hz) here?

I'm not smart enough :-(

And what 'steepness' ?

12dB/octave ?

I'm considering doing DSP crossover with this and would like to know ideal DSP crossover point and steepness?


1620732214705.png
 
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Mudjock

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Crossover points are 1.2 kHz between the woofer and mid and 5.8 kHz between the mid and tweeter. The mid-tweeter crossover is more like 24 dB/octave. The woofer-mid crossover is a little shallower and not completely symmetric. Both drivers have pretty wide off axis dispersion at that point, so I think you would be fine starting at 24 dB/octave if doing an active crossover.
 
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Hi what would be the maximum watts for these speakers. I am planning to use them for my home theater. 9.4.8 atmos setup. When I put it on an online db calculator to see if it reaches reference level at MLP in a large room it looks like it can't at 120w.... Either I make the room smaller or find a more sensitive speaker.

Question 2 what would be a good atmos speaker to pair with these? With the same tweeter.

Crossover points are 1.2 kHz between the woofer and mid and 5.8 kHz between the mid and tweeter. The mid-tweeter crossover is more like 24 dB/octave. The woofer-mid crossover is a little shallower and not completely symmetric. Both drivers have pretty wide off axis dispersion at that point, so I think you would be fine starting at 24 dB/octave if doing an active crossover.
 
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Mudjock

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Hi what would be the maximum watts for these speakers. I am planning to use them for my home theater. 9.4.8 atmos setup. When I put it on an online db calculator to see if it reaches reference level at MLP in a large room it looks like it can't at 120w.... Either I make the room smaller or find a more sensitive speaker.

Question 2 what would be a good atmos speaker to pair with these? With the same tweeter.
I would think the DIY 3.1 can handle more than 120W peaks, particularly when a sub is used. Amir's distortion testing showed very controlled behavior at 96 dB continuous above about 60 Hz. The mid and tweeter are well protected by the high crossover points, so the real limitation is woofer excursion and sensitivity/amplifier power. With a high pass at 80 Hz, the limitation will probably be amplifier power with any musical or home theater content.

I'm not aware of an atmos speaker currently available using that tweeter (HiVi RT1.3).
 
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I would think the DIY 3.1 can handle more than 120W peaks, particularly when a sub is used. Amir's distortion testing showed very controlled behavior at 96 dB continuous above about 60 Hz. The mid and tweeter are well protected by the high crossover points, so the real limitation is woofer excursion and sensitivity/amplifier power. With a high pass at 80 Hz, the limitation will probably be amplifier power with any musical or home theater content.

I'm not aware of an atmos speaker currently available using that tweeter (HiVi RT1.3).
Thanks so much for the response. Another question would be is this rated at 4 ohms or 8 ohms? Currently thinking which should I go with between these 2 hypex amp modules. I really want to go with the NC502MP so I can drive any speakers in the future.

NC502MP
- 2x450w @ 2ohm
- 2x500w @ 4ohm
- 2x350w @ 8ohm


NC252MP
- 2x180w @ 2ohm
- 2x250w @ 4ohm
- 2x150w @ 8ohm
 

Mudjock

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The minimum impedance is just under 4 ohms. Some speakers "rated" at 4 ohms have minimum impedance under 3 ohms. So, I would rate it as a 4 ohm speaker, but pretty amp-friendly for a 4 ohm speaker.

I think given your concerns about reaching reference levels in a large room, the extra headroom the NC502MP provides would be worth the relatively small cost increase.
 
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The minimum impedance is just under 4 ohms. Some speakers "rated" at 4 ohms have minimum impedance under 3 ohms. So, I would rate it as a 4 ohm speaker, but pretty amp-friendly for a 4 ohm speaker.

I think given your concerns about reaching reference levels in a large room, the extra headroom the NC502MP provides would be worth the relatively small cost increase.
nice thank you :)
 
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Thinking out loud here: would this speaker kit perhaps be a good platform to develop a DIY high-value active monitor?

My take of this review is that the kit, with the Sehlin/ScottS/Mudjock perfectionist crossover mod is pretty good, and becomes really good with a little EQ.

So what if the speaker-level crossover is discarded completely, and the crossover is implemented at line/pre-amp level, then fed into three amplifiers (one for each driver)? A variation on this idea is for the speaker input to be digital, and the crossover is implemented via DSP, followed by three amplifiers.

I don't have enough knowledge/experience to know how feasible it is to "convert" a speaker-level XO to line-level. I am assuming the line-level XO would be smaller and cheaper, since the components don't need to be rated for high power.

If my assumption is correct (line-level XO is small), then I think it wouldn't be too hard to have a PCB like this: input buffer -> XO -> two class D amps (one configured for stereo output, one configured for PBTL output). Since the speaker cable lengths would be very short (i.e. just inside the box), the class D amps won't need the typical (large) EMI-supressing LC filter (can get by with a cheap/small ferrite bead solution). The TI tpa3220 and Infineon ma12070 class D chips have simple PCB implementations, and are pad-down ICs that use the PCB as a heatsink. The TI tpa3250 is also a candidate, but has a more complex implementation.

Thoughts?
 

Mudjock

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One certainly could go all active with the 3.1's. You would just need to make a new input cup with six connections (two for each driver). You would directly wire the drivers to the inputs. You would also need a 6 channel amplifier for a stereo pair.

The primary issues to correct for an ideal response are not in the crossover regions, but rather a slight dip centered around 300 Hz and a dip/directivity error around 2.1 kHz. 2.1 kHz is too low in frequency to bring in the tweeter to help with directivity without significant distortion issues. Based on that, I'm not sure that an active crossover would help much versus the passive crossover plus eq.
 
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One certainly could go all active with the 3.1's. You would just need to make a new input cup with six connections (two for each driver). You would directly wire the drivers to the inputs. You would also need a 6 channel amplifier for a stereo pair.
I was thinking that the existing passive crossover PCB would removed, and in it's place, the DSP or line-level XO, plus three amplifiers. So the input to the enclosure itself would be a single digital connection (e.g. SPDIF) or a line-level input (RCA or XLR). There would also be a connector for power input (either AC or DC from something like a laptop brick). IOW, turn these into studio-type active monitors.

The primary issues to correct for an ideal response are not in the crossover regions, but rather a slight dip centered around 300 Hz and a dip/directivity error around 2.1 kHz. 2.1 kHz is too low in frequency to bring in the tweeter to help with directivity without significant distortion issues. Based on that, I'm not sure that an active crossover would help much versus the passive crossover plus eq.
Maybe this is the error in my thinking, but I was assuming you could do a "twofer" with DSP or PLLXO: 3-way XO and the additional corrections you mention above. The result being a "plug and play" speaker with ideal response.

Either way, definitely curious to see how the other Hivi kit, the 2.2A, compares. The 3.1's definitely look like a great value!
 
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I was wondering if anyone can tell me if I can just seperate the tweeter/ midrange from the woofer in the crossover for bi-amping or is there going to be a problem with the load my amps will see? I'm using clone monoblock Pass Aleph 30's for the top end and a crown xls 1502 for the lows.
 
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I didn't like the cheap binding post cup that came with so I got a better one. I didn't get the corner radius right but it's on the back anyway. The crossover isn't soldered. I want to bi-amp these when I figure it out.
 
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Mudjock

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I didn't like the cheap binding post cup that came with so I got a better one. I didn't get the corner radius right but it's on the back anyway. The crossover isn't soldered. I want to bi-amp these when I figure it out.
I always thought it was interesting (odd) that HiVi chose to include a biwire input cup, but not utilize it. What I would do is connect the upper pair of input terminals to the input + and - positions on the crossover board. The woofer inductor (the longer coil on its side adjacent to the input + and - holes) should have the lead that is connected to input + disconnected and instead connected directly to the lower positive input terminal. The lower negative input terminal can remain connected to the upper negative input terminal as they both go to ground. You can either do that by just leaving the negative copper bus bar in place or by connecting the two negative terminals inside the cabinet to make it mistake-proof.
 
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I always thought it was interesting (odd) that HiVi chose to include a biwire input cup, but not utilize it. What I would do is connect the upper pair of input terminals to the input + and - positions on the crossover board. The woofer inductor (the longer coil on its side adjacent to the input + and - holes) should have the lead that is connected to input + disconnected and instead connected directly to the lower positive input terminal. The lower negative input terminal can remain connected to the upper negative input terminal as they both go to ground. You can either do that by just leaving the negative copper bus bar in place or by connecting the two negative terminals inside the cabinet to make it mistake-proof.
So it would be fine to have the 2 amps grounded together?
 

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