Hivi 3.1A DIY Speaker With Sehlin Mod Review

[Mudjock]

Adding a second woofer would change the crossover some. Playing around with my simulation of the crossover, I would try the following.

Wire the two woofers in series with each other - This will give you the same voltage sensitivity, but approximately twice the impedance. To compensate for that, you will need to change the component values for the woofer low pass circuit.

Change L4 to 3 mH
Change C5 to approximately 24 uF (27 uF is probably close enough, as that is a more common value. I wouldn't go less than 24 uF).
Change R3 to 4 ohms

This may not give exactly the same response as the modified 3.1A due to the different driver layout, but seems to give a very similar FR with a few simplifying assumptions.

 

[AllenW]

I would like to take a little time to provide more information and address a few questions and comments.

First of all, many thanks to Amir for the review. I put him through a lot for this review. I freely admit that most of the speakers I build can best be thought of as prototypes. Drivers are frequently connected with removable connectors as opposed to solder. I've had a last minute defective driver replacement at a DIY event/competition and it's a lot easier than bringing a soldering iron... Crossover boards are often mounted in such a way to be removable for future tweaking. All of these issue came home to roost for this review as Amir's first comment was that something was rattling inside the cabinet, which turned out to be the crossover board that came loose during shipping. When Amir reattached that and ran his tests, it was apparent that the tweeter had no output, so he had to open them back up, reattach the tweeter wires, and remeasure. I wouldn't have blamed him at all for sliding these down on the Panther scale, but he did the opposite. If I send anything in the future, I will at least make sure the assembly methods are fit for commercial ground transportation.

HiVi deserves all the credit the cabinet design and tuning that protects the woofer and the midrange, enabling distortion to stay under control at high output. They picked a good set of drivers for this kit, which is what initially interested me, as I had previously heard all of the drivers (and worked with the midrange on another project).

I always thought it was odd that they chose to design a crossover with such a rising response. This is straight from the swanspeakers website.
View attachment 81674

I saw an assembled pair for sale on our local craigslist and decided that it would be fun to see if they sounded like the manufacturer's response curve indicated and see what it would take to flatten the response curve. I step through the process on the Midwest Audio Club forum

MAC/DIY HiVi DIY 3.1 Post

I summarized the results on my Sehlin Sound Solutions page. The speakers reviewed include the option 4 "perfectionist option" crossover.



This is certainly true. There are a number of reasons for that, but the name is perhaps a bit misleading. I set out to see if simply tweaking resistors could fix the crossover, but that wound up not to be the case. Although I could bring the mids and highs in balance with the bass, the response was very uneven as shown in options 1-3. For option 4, I constrained myself in a couple of ways:

1. Add no complexity to the assembly process versus the original kit
2. Keep the cost low

These considerations meant that whatever I did would allow use of the circuit board that comes with the kit and would not touch the most expensive components (larger inductors and capacitors). The resulting mod only adds about $25 in parts to the $299 kit.

View attachment 81679

I was very relieved that the on axis response and impedance (actual driver measurements with a simulated crossover applied) closely matches the on axis response from the Klippel NFS.



It is possible to tweak the crossover to bring the level down a dB or two where it is elevated. The changes I would recommend include

1. Increase C5 (in the woofer circuit) from 47 uF to 68 uF.
2. Increase R2 from 2 ohms to 3 ohms in the midrange circuit
3. Increase R1 from 5.6 ohms to 6.8 ohms (7 ohms would be fine depending on which is available) in the tweeter circuit.

View attachment 81685

I'm not sure if that will sound better in all rooms as part of the reason I set the mid and tweeter level where I did was to avoid the upper bass region from standing out and sounding too "tubby"



I have long been a fan of dome and other unusual mids. Here is a recent picture of my listening rotation.

View attachment 81683
The 3 way's with the dome mid are an unpublished design because the 3" Tang Band dome mid is no longer available to DIY'ers.

View attachment 81684

This is the Indium 7 design which was one of my Parts Express Design Team projects and still can be built. It uses the same mid as the HiVi DIY 3.1A (except for a slightly different flange).

This thing can't hold much more. It's 2.5 lbs now.

 

[AllenW]

I would like to take a little time to provide more information and address a few questions and comments.

First of all, many thanks to Amir for the review. I put him through a lot for this review. I freely admit that most of the speakers I build can best be thought of as prototypes. Drivers are frequently connected with removable connectors as opposed to solder. I've had a last minute defective driver replacement at a DIY event/competition and it's a lot easier than bringing a soldering iron... Crossover boards are often mounted in such a way to be removable for future tweaking. All of these issue came home to roost for this review as Amir's first comment was that something was rattling inside the cabinet, which turned out to be the crossover board that came loose during shipping. When Amir reattached that and ran his tests, it was apparent that the tweeter had no output, so he had to open them back up, reattach the tweeter wires, and remeasure. I wouldn't have blamed him at all for sliding these down on the Panther scale, but he did the opposite. If I send anything in the future, I will at least make sure the assembly methods are fit for commercial ground transportation.

HiVi deserves all the credit the cabinet design and tuning that protects the woofer and the midrange, enabling distortion to stay under control at high output. They picked a good set of drivers for this kit, which is what initially interested me, as I had previously heard all of the drivers (and worked with the midrange on another project).

I always thought it was odd that they chose to design a crossover with such a rising response. This is straight from the swanspeakers website.
View attachment 81674

I saw an assembled pair for sale on our local craigslist and decided that it would be fun to see if they sounded like the manufacturer's response curve indicated and see what it would take to flatten the response curve. I step through the process on the Midwest Audio Club forum

MAC/DIY HiVi DIY 3.1 Post

I summarized the results on my Sehlin Sound Solutions page. The speakers reviewed include the option 4 "perfectionist option" crossover.



This is certainly true. There are a number of reasons for that, but the name is perhaps a bit misleading. I set out to see if simply tweaking resistors could fix the crossover, but that wound up not to be the case. Although I could bring the mids and highs in balance with the bass, the response was very uneven as shown in options 1-3. For option 4, I constrained myself in a couple of ways:

1. Add no complexity to the assembly process versus the original kit
2. Keep the cost low

These considerations meant that whatever I did would allow use of the circuit board that comes with the kit and would not touch the most expensive components (larger inductors and capacitors). The resulting mod only adds about $25 in parts to the $299 kit.

View attachment 81679

I was very relieved that the on axis response and impedance (actual driver measurements with a simulated crossover applied) closely matches the on axis response from the Klippel NFS.



It is possible to tweak the crossover to bring the level down a dB or two where it is elevated. The changes I would recommend include

1. Increase C5 (in the woofer circuit) from 47 uF to 68 uF.
2. Increase R2 from 2 ohms to 3 ohms in the midrange circuit
3. Increase R1 from 5.6 ohms to 6.8 ohms (7 ohms would be fine depending on which is available) in the tweeter circuit.

View attachment 81685

I'm not sure if that will sound better in all rooms as part of the reason I set the mid and tweeter level where I did was to avoid the upper bass region from standing out and sounding too "tubby"



I have long been a fan of dome and other unusual mids. Here is a recent picture of my listening rotation.

View attachment 81683
The 3 way's with the dome mid are an unpublished design because the 3" Tang Band dome mid is no longer available to DIY'ers.

View attachment 81684

This is the Indium 7 design which was one of my Parts Express Design Team projects and still can be built. It uses the same mid as the HiVi DIY 3.1A (except for a slightly different flange).

Would it be okay to put a 2.5 in R3 with this option?

 

[Mudjock]

Would it be okay to put a 2.5 in R3 with this option?

If you have R3 at 2.5 ohms, C5 should be 27 to 30 uF

 

[AllenW]

If you have R3 at 2.5 ohms, C5 should be 27 to 30 uF

I'm talking about the option with C5 being 68uf.

 

[drfous]

What capacitors are folks using for 5.6 uF? Not much selection on digikey that would fit on the board.

Thanks for the work on the upgraded cross over. I got the kit the other day and need to source a few parts.

 

[AllenW]

What capacitors are folks using for 5.6 uF? Not much selection on digikey that would fit on the board.

Thanks for the work on the upgraded cross over. I got the kit the other day and need to source a few parts.

Parts Express

 

[Mudjock]

I'm talking about the option with C5 being 68uf.

For that case, the biggest change going to a 2.5 ohm resistor is that it pulls down the response a little (about 1 dB) from 300 Hz to 800 Hz. I think 2 ohms is likely the better way to go (particularly from 300 to 500 Hz, where one would prefer not to lose any more output, but 2.5 won't be a deal breaker.

 

[AllenW]

 

[AllenW]

Great! Got them hooked up and one woofer is bad.

 

[Mudjock]

My woofers measured close enough to published spec that I think you will be okay with just one.

 

[AllenW]

My woofers measured close enough to published spec that I think you will be okay with just one.

I already ordered one. $55.40 shipped.

 

[AllenW]

My woofers measured close enough to published spec that I think you will be okay with just one.

The mod I used from page 4 with the 68uf at c5 sounds very good. I checked it with Tom Waits Glitter and Doom album and if there was any tubby sound to the speaker that will make it obvious. It sounded perfect.

 

[AllenW]

To say these speakers are a little bright is an understatement. They make my cornwall 2's sound laid back. Some recordings are great but if you listen to classic rock it's unbearable unless it's turned way down.

 

[AllenW]

I spoke to soon. After a few days of letting them play they settled down nicely. They have a very smooth almost soft sound now. I think they'll get better with some more time. This is definitely not just getting used to them. They hurt my ears when I first plugged them in.

 

[sed_12]

I accidentally flipped the back port of both my speakers. Meaning the woofer and the back port hole are lining up. How do you think that affects the sound ?? I did the perfectionist mod too . I was hoping for perfect sound

 

[AllenW]

I accidentally flipped the back port of both my speakers. Meaning the woofer and the back port hole are lining up. How do you think that affects the sound ?? I did the perfectionist mod too . I was hoping for perfect sound View attachment 147395View attachment 147394

I wouldn't think it would matter as long as the port doesn't touch the woofer magnet. I almost did the same thing. Fortunately I folded the box up after taping it together checking for fit and I noticed it. No going back once the glue is on. They look nice by the way.

 

[Mudjock]

I accidentally flipped the back port of both my speakers. Meaning the woofer and the back port hole are lining up. How do you think that affects the sound ?? I did the perfectionist mod too . I was hoping for perfect sound

The concern with the port behind the woofer is that some of the woofer output, midrange and higher frequencies, can exit directly out through the port. If the port is away from the woofer, that output can be at least somewhat attenuated by damping material in the cabinet on its way out. If you are having that issue, then one solution would be to place a damping panel behind the speaker. Depending on the placement of your speaker currently, it may or may not be needed.

 

[AllenW]

For that case, the biggest change going to a 2.5 ohm resistor is that it pulls down the response a little (about 1 dB) from 300 Hz to 800 Hz. I think 2 ohms is likely the better way to go (particularly from 300 to 500 Hz, where one would prefer not to lose any more output, but 2.5 won't be a deal breaker.

These have the potential to be perfect speakers. If it wasn't for the tubby sound in the bass these would be the best I've ever heard. If you ever deside to fix that issue with the mod I used let me know. These would easily be worth the cost to build a crossover from scratch.

 

[AllenW]

I think I'm going to put another set of these together stock and send them to GR research and have him build a crossover for them. He seems to get a lot of praise for his work. I think these are worth it.