How To Make Cheap Speakers Sound Unbelievable.

hey everybody welcome back today we've got a little mini monitor that's been sent to us from a customer this is another pulk model it's the pulk r200 and it's a fairly well-made little speaker it's not without issues but overall it's got some good qualties let's take a look at this thing first of all nice looking box that that they send out in this thing it's got a textured finish I'm sure it's very inexpensive to spray it in this finish over MDF but it looks nice Grill's well made uh I like the way it goes on it looks clean it's magnetically held on it's easy to remove there are some issues with the grill as far as the way thing measures but overall looks okay the port on this thing I don't know what they're thinking on this thing uh big wacky Center piece poking out of this port like that's supposed to do something they should have spent the money on a little better crossover parts that would have done a little more than what that Port did um one brace running through the box that's it um woler is well it's a stamp still frame I'm not a big fan of the stamp still frame and it's a very heavy cone so it's not without issues but it is some type of a whatever they're calling this paper composite something or another that has a pretty decent amount of internal damping it's not that bad but it it's not a great response um there's a lot of parts on this thing correcting the response of this driver in My Views it would be money is better spent in development of the driver and creating a smooth rolloff rather than having to put a whole bunch of crossover Parts on there to correct a roll off that is or to correct a response that is not smooth um Tweeter wise little uh ring radiator tweeter it measured pretty well both of these fit on and have little uh beauty rings that fit over the ends of them to finish out the look um this one is held on magnetically I like the way it goes on um works really well it's a little difficult to remove but once you kind of get it get it off um it works okay binding post wise they look they look nice it's it's a good look however the whole back of it is just steel the terminal that this thing connects to or steel the screws the nut on the end of it here is All Steel not what you want in your signal path I mean in general if you take a magnet to a crossover and it's sticking out tell everything on there that's not a good sign like all these s cast resistors have Steel in plates on them um the electrolytic capacitors that are on this thing they all have Steel inss on them uh of course there's iron core inductors on the woofer circuit at least in the Tweeter circuit there was a little air core inductor one polypropylene cap one polyester cap come on man in the woofer circuit the all the Caps were electrolytic so I mean that's going to smear and suck that image right out of it just muffle everything along with the tiny gauge uh iron core inductors so definitely built to a price point but how did it measure um Fair pretty fair good good and bad let's take a look at everything frequency response wise in general looks smooth I mean first thought was wow measures really smooth there's a little Peak there at um about 1100 htz is it an amplitude Peak or is there stored energy there at that Peak let's look at the spectral Decay the spectral Decay is the tail all of all measurements it gives you the frequency response but it also gives you the Decay over time and as you can see that little Peak there does have some stored energy there and the reason I point that out is those are audible issues that is a distortion there that it's holding that residual ring that residual energy and it's taking longer for it to dissipate that and as you bring power levels up louder and louder it gets more and more extreme um think of it as right at the top of the female vocal just a little bit of on on top of everything else piano notes tend to not release but tend to carry on and ring longer than they're supposed to not because there's a longer decay in the recording but because this is adding additional Decay on top of everything else so there's that going on um looking at the grill effect you can see the grill is is having some effect on it um the crossover point was rather high and you can see by the vertical off axis there's a dip that starts as you start moving up um that's when you're physically getting the woler um further away in time than the Tweeter and that offset and the time arrival makes them out of phase creates a hole so they're more in Phase if you're at Tweeter level and Below but if you get above it this the the sound is going to change and the overall and room response may be a little uneven because of it horizontal off axis looks fine looks normal normal drop off that you'd see in most drivers and the impedance shows that it is a 40 load now what was uh troubling to me when I first started this uh little upgrade on this is well I looked at that stored energy there in the woler response at about 1100s and thought I got to fix that that's an audible issue other than that it looks great you could have just stuck with the original crossover if it wasn't for that issue uh and I thought there's another thing there I could I could push that crossover point a little lower and get the drivers in Phase a little better over a wider range and improve the overall in room response of the speaker so I thought all right let's let's design something new for it that addresses some of those issues so let's look at the individual driver responses Tweeter response isn't that bad it's a little lumpy but it's it's manageable and it does play down really low so that told me something very important that I could easily push that crossover Point down a little lower no issue with the Tweeter reaching down into a lower range the woer response however it's rough um where the baffle step loss is it's compounded by a ramped up response there is a notch filter that was in the original crossover on this thing on here that is removing a peak that is about 700 htz other words it's taking that step loss and instead of just putting a coil on it and pulling it down which would create a dipped area they're pulling down the peak with a notch filter which is not a bad idea however they ignored the peak right after it so there was there was a lot to have to consider when doing this crossover and it's not going to be just a couple of parts I wound up leaving the notch filter at 700 HZ that they had and putting a little bigger inductor on it and adding another little Notch filter right there at 1100 HZ to fix that ringing going on right there and putting a little more of aggressive cap on the end of it to try and round that response off nice and smooth and pull it back a little bit and let's look at the response I got out of this thing on the overall crossover um note the way the wolfer is rolling off and how smooth that is and the tweeter's curve how smoothly it rolled into it tweeter's curve had a little whoop-de-do there at the bottom of its range and at one point I put a filter on there that flattened it out but it also has a peak in the off axis right there at 3K where that dip is so one's kind of counteracting the other a little bit so I took the the more aggressive filter out of it went ahead and let it look like you see here in the on the chart and in the off axis it look great in fact at about 10 to 15° off axis the thing's a flatline so it that turned out really well and let's look at let's look at these as as a comparison let's do that that's that's always a little bit more fun let's look at the frequency response of the original versus the frequency response after the upgrade notice again that little bump at 1100 HZ is gone let's look also at the spectral Decay let's look at the before and the after spectral Decay you notice the after is free of that stored energy so the overall response of the whole thing is much cleaner no more ringing in that area um Also let's let's look at the vertical off axis let's look at a before and an after of the vertical off axis notice now the drivers are more in phase over a wide range so um it's going to give you a more balanced in room response in all directions and if you stand up and sit down you're not going to hear a big tonality change it's going to be consistent horizontal off axis is very much like it was we can look at the before and the after and the horizontal off axis not a lot of change there a lot of it just has to do with the off-axis response of the drivers and then let's look at the impedance I I'm not thrilled with the impedance with the new crossover let's look at the before and the after it was a 4 ohm load I made it drop down to a three ohm load because we're getting a little more aggressive with this woofer we've added a second Notch filter and I've put a bigger cap on there to pull that thing back a little bit and not let it play way up to 3 or 4,000 Hertz so balance things out a little bit sometimes when you have to use corrective filters to balance things out sometimes it causes that impedance to drop a little bit more and that's what happened in this case we're dropping down to a minimum a 3 ohms in that one area versus where it was at 4 Ohms not a big shift there um it's still normal impedance minimals for a 4 ohm speaker and at least that dipped area is higher up in frequency not down low where it's going to demand a bunch of current so um what we did with an upgrade on this thing is we've got much high quality Parts going into this little upgrade kit all Air core inductors much bigger gauge uh inductors on there good quality resistors no Ferris materials in the signal path uh all JB poly caps there's a bypass JB cap on the Tweeter circuit which is a inexpensive way of kind of taking that up to another level uh a set of tube connectors to replace these cheesy binding posts that are on here in fact you should be able to remove these and then just drill those holes out to a bigger hole to a 716 inch diameter and the tube connectors will fit right in you can glue them into this plastic cup and if you want you can hot glue a little on the back side to make sure that they're secure in there but easy to mount tube connectors right into this the wiring is going to go from this PVC jacketed stuff with these push-on connectors to high Purity copper and polyethylene with no connectors in the signal path you're going to point too Point wire this stuff should all fit right in the bottom of the Box no problem and um that should improve signal transfer across the board also if you add a little more insulation to this thing you'll do away with some of that resonance that was in the port if you look at the original impedance response in fact let's pull that up one more time and take a look at it uh you'll see a couple of little Ripples and the impedance one down around 25 Herz and one right at the tuning frequency of the port uh found that that was some internal standing Reflections within the box that was coming back through that Port so adding just a little bit of fiberglass insulation in there to keep those standing waves from bouncing around in the box that knocked it down and then that stuff was gone you can see the new impedance curve you can see that that wasn't there anymore another thing you might want to consider I didn't throw it in as an upgrade because I didn't feel like it was critical cuz this box is fairly well built but if you wanted to order sheet of noes and line these things with noest it will definitely tighten things up a little bit and improve the base response on it but I didn't feel it was an absolute fix that had to be done on this one because it's a small box and it does have one brace running through it so I'm trying to keep it at a budget level and if you want to upgrade it you can that's why I'm throwing in the Sonic cap on the Tweeter circuit as an additional upgrade if you want to bump that up a little bit more um it is a an additional um let's see it was an additional $89 if you wanted to add Sonic caps to the Tweeter circuit so um great little upgrade uh it's definitely worth doing if you own this thing already get your feet wet doing a little DIY uh work and upgrade this thing and take it from here to here in performance think it's going to open up the sound of this thing your Imaging layering everything is going to be much open open much more open and much more uh controlled better resolution better it's just it's not in day difference when you go from this stuff to high quality parts and when you get stuff like this out of the signal path especially when there's a lot of it it really adds up so great little upgrade um that's it for this little episode here I appreciate you guys watching I know you love watching upgrade videos um hit the Subscribe button if you have that way you get notification when we shoot new videos and thanks for watching see you guys in the next one

Channel: GR-Research

Views: 57,619

Keywords: Tuesday Tech Talk, audiophile, hifi, loudspeaker, fullrange driver, comb filtering, GR-Research, Danny Richie, crossover design, measurements, best loudspeakers, tube amplifier, preamplifier, diy speakers, audiophile speakers, audiophile music, amplifier, best voice, audiophiles, high end, baffle step loss, open baffle, fast bass, subwoofers, line source, drivers, high power handling, low distortion, the room, speaker upgrade, audiophile loudspeakers, crossovers, DIY Audio, soundstage

Id: 7rrQJWKwdQQ

Length: 14min 6sec (846 seconds)

Published: Tue Mar 19 2024