Anyone know the impedance of the 4" speakers

  • I bought a used Spark and I'm playing around with getting rid of the boominess. Most of the presets I've tried have needed the bass and midrange cut below halfway. I'd like to play around with other 4" fullrange speakers, but need to know what the amps/speaker impedance match its. I have no warranty, so the results good or bad are on me. I just don't want to stress the amps out.

  • @madmarcus1960
    I measured 3.6-3.7 ohms which tells me they are 4 ohm speakers. I made a slight improvement in bass response, to my ears, by plugging the bass port(under the grill) with some damping close cell foam, I had from Parts Express. To me , it removed some of the boominess. Since I own it without support, I'm going to try some other 4" full range speakers in the 25-30W RMS range. If anyone's interested, I'll report my results.

  • in those size speakers, I'd say 4 ohms guaranteed, standard impedance, there's no way PG would pay extra for any other boutique or custom impedance speakers and keep the price this low.
    thats just my guess,

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    I know lots of people are going to say, why put more $ into it. But I got it(the Spark) on the cheap and want to see if I can improve on it.

  • @madmarcus1960 definitely interested in the results...

  • @madmarcus1960 I got my new Spark 40, and, being curious, wanted to look inside to see the speakers. My motive was to maybe install an external speaker jack, or figure out how to send the headphone signal to some kind of preamp. I took the back off, but couldn't see how to get the 2nd. back out. Can you tell me if there's a non-destructive way to remove the back?

  • @madmarcus1960 said in Anyone know the impedance of the 4" speakers:

    I ...need to know what the amps/speaker impedance match its. I have no warranty, so the results good or bad are on me. I just don't want to stress the amps out.

    The manual specs their impedance at 4ohms

  • I measured 3.6-3.7 with a meter, so 4 ohms is correct. I also like the idea of moving the speaker outs to jacks on the back wall. The would be and easy mod and open up a world of options for lower powered speakers

  • The back panel is fake, it covers a MDF back wall for the speaker cab portion, and the back access tot he guts of the electronics. It would be easy to drill through both to allow mounting speaker jacks. +/- of each speaker wiring to the center and ground of a mounted jack. Pretty easy mod if your comfortable violating your warranty. I'd use a step drill to easily blow through MDF for the correct size of the jacks mounting hole. You'll just need a jack long enough to go through both pieces.

  • @madmarcus1960 - Yeah, but how do I get in there to wire the jacks into the circuit? Looks like they glued the hidden MDF in place into some rabbets in the bottom and sides. Time to break out the oscillating cutter?
    Never mind, my bad. Take the front grill off, duh.

  • Take the speakers out from the front. The remove the speaker wiring and you'll need to solder extensions for them to reach any jacks installed into the back panels.

    Here is the finished speaker replacement for me using the above mentioned AMZ purchase.

    0_1597689691125_Spark 1.jpg

  • 0_1597689777794_Spark 2.jpg

    Between the new speakers and the blocked bass port(Acoustic closed cell foam from Parts Express), the unit sound 100X better IMHO.

  • @madmarcus1960 I had some high-density foam, about 1/2" thick, which had been packing material from some electronics a while ago. It's not springy like foam rubber. I cut a circle to fit, and pushed it in. I notice a change. Very nice!

  • @madmarcus1960 Very interesting. I'd love to see somebody that had a good mic do a before and after sound test comparison, but I can only imagine that the sound is way better.

    I just crammed a rag in the bass port and ordered one of the speakers above from Amazon and removing the grill and checking out the speaker connections shows it's basically "plug and play". You really don't have to modify anything from what I can tell. Depending on how things go, I might order a second speaker, but I want to see how the first speaker sounds combined with the bass port being plugged first.

  • One note is the speaker connections on the PRVs I bought are horizontal and require that you kitty corner the speaker into the hole. But I did get them to fit with no rework. The mounting holes align with a little side to side adjustment, once the speaker sits in the opening

  • @madmarcus1960 - Following this regarding jack & line out.
    Please let us know what you run the new line out to. And any electric current, impedence, or wattage considerations.
    I saw the Steve Stine, Positive Grid live stream on Facebook a few minutes ago, and he always runs the Headphone line out to his digital audio interface, then wherever. I'll be getting an interface eventually for a condenser mic I have, but your fix would be good for simplifying when I don't need to hook up the interface/preamp.

  • @madmarcus1960 Awesome! Any sense as to what brand of speaker was in there prior? Man if you had a decent mic setup and had prior footage to show comparison between stock and these PRVs, there would be a lot of grateful Spark owners out there including yours truly. Congrats.

  • Just tried the Part Express 4" speaker option but will be sending these back. Although listed as 4", the driver is 1/4" to 3/8" smaller so there's no easy way to mount since there's no wood behind the screw holes. I wired them up anyways with the speakers held in by gravity. They had less bass but not necessarily in a good way. It sorta over shoots the idea of less boominess and goes right to a thin, small sound; facing upwards probably didn't help. The extended high end was noticable but starts to add a little sizzle (not good for modelers but not terrible). Due to the mounting issues and small sound, I didn't spend long trying to see if the sizzle could be dialed out.

    I spent $70 for the pair and like the original speakers better. The originals are more efficient with additional volume at the same amp settings. Having compared them to something else, I can hear the originals have a mid range honk I hadn't noticed before. I'll try one more alternate to correct next but would be ok living with the original speaker if needed. Tonally, the speaker just doesn't compete with the THR10.

    If Positive Grid added a mono 7 or 10 band EQ block just after the amp block, the boominess could be dialed down and the upper highs massaged to taste. It would be far more versatile to accommodate different styles of music and overcome the speaker's limitations.

  • Visaton FR10 4 ohms are a perfect fit, co-axial, cheap as chips and sound better than the oem's (in my opinion).

    Specs below from the manufacturer. Just google visaton fr10 4 ohms to find a seller in your country. (farnell, mouser, digi-key, etc)