Monitor 10B options for subs or replace entire system

[pglbook]

I have to jump in about the Polk Monitor 10s as I have a few pairs myself. The Polk Monitor 10 is not a 4 OHM speaker. The Polk Monitor 10As are rated at 6 OHMs and after that all of the Monitor 10s (including 10Bs) are rated at 8 OHMs. Also, someone in this thread recommended a posssible tweeter upgrade. That depends on what tweeter is in the Polk Monitor 10. If they have the Peerless tweeters, DO NOT change them at all. The Perless tweeter is one of the best sounding tweeter of all time. I have two pair of Polk Monitor 10s - a pair of 10As and another pair of Monitor 10s (a very early model with 2 external fuses in the back; all other Monitor 10s I had seen only had 1 external fuse on the back) and both pairs have the Peerless tweeter and both sound amazing. My Polk Monitor 10s were my favorite speakers of all the speakers I have ever had...until a month ago when I bought a nice pair of Polk SDA 2B TL from forum member bluecomet. And now my Monitor 10s sit idle while I listen to my SDA 2Bs which are incredible. I did not think anything could sound better than the Monitor 10s but the SDA 2Bs are in a league of their own. Thanks.

[westmassguy]

I have to jump in about the Polk Monitor 10s as I have a few pairs myself. The Polk Monitor 10 is not a 4 OHM speaker. The Polk Monitor 10As are rated at 6 OHMs and after that all of the Monitor 10s (including 10Bs) are rated at 8 OHMs. Also, someone in this thread recommended a posssible tweeter upgrade. That depends on what tweeter is in the Polk Monitor 10. If they have the Peerless tweeters, DO NOT change them at all. The Perless tweeter is one of the best sounding tweeter of all time. I have two pair of Polk Monitor 10s - a pair of 10As and another pair of Monitor 10s (a very early model with 2 external fuses in the back; all other Monitor 10s I had seen only had 1 external fuse on the back) and both pairs have the Peerless tweeter and both sound amazing. My Polk Monitor 10s were my favorite speakers of all the speakers I have ever had...until a month ago when I bought a nice pair of Polk SDA 2B TL from forum member bluecomet. And now my Monitor 10s sit idle while I listen to my SDA 2Bs which are incredible. I did not think anything could sound better than the Monitor 10s but the SDA 2Bs are in a league of their own. Thanks.

Polk was VERY generous with the 6 ohm rating they gave to the Monitor 10s, wishful thinking would actually be more accurate. I've read several reveiws with accompanying test reports from that era.
Excerpt from Stereo Review, and Hirsch-Houck Laboratories: "The speaker impedance reached a minimum of 4 ohms at 33 and 150 Hz and a maximum of 15 ohms at 55 Hz ( there was another maximum below 20 Hz, where we did not measure it). From about 500 Hz upward the impedance was always at least 7 ohms. Strictly speaking, the model 10 should be rated at 4 ohms although Polk gives the impedance rating as 6 ohms."
And: " The sensitivity of the Model 10 was moderate so that a drive level of 2.83 volts (normally one watt into 8 ohms) produced a sound pressure level of 89dB at a one meter distance. This is relatively low for a vented system ( a passive radiator can be considered a vent substitute or equivalent)"
So we have a relatively low sensitivity speaker, that should have been rated 4 ohms, not 6. If you look at the schematics for all the Monitor 10s, you have two 8 ohm nominal MW65** woofers in parallel, which halves the resistance. The original 10s had 6501 woofers which had a very high 7.75 ohm DCR, while all later models had 6503s with lower DCRs. If anything the later models would be an even tougher load than the early models.


[StantonZ]

Polk was VERY generous with the 6 ohm rating they gave to the Monitor 10s, wishful thinking would actually be more accurate. I've read several reviews with accompanying test reports from that era.
Excerpt from Stereo Review, and Hirsch-Houck Laboratories: "The speaker impedance reached a minimum of 4 ohms at 33 and 150 Hz and a maximum of 15 ohms at 55 Hz ( there was another maximum below 20 Hz, where we did not measure it). From about 500 Hz upward the impedance was always at least 7 ohms. Strictly speaking, the model 10 should be rated at 4 ohms although Polk gives the impedance rating as 6 ohms."

+1: My 10B's are definitely pushing 4 Ohms (which is why I use the low impedance switch on my amp). Like I said in my previous post, try some 'tip toes' and/or try a beefier amp.

[jeremymarcinko]

Polk is accurate 6-8 ohm depending on model. given impedance fluctuates with load on all loudspeakers. Its normal for 8ohm speakers to dip down to 4ohm. Thats its stated "nominal"

[canadianicon25]

just add a sub. sub's are easy. just adjust the crossover point until it sounds right. with full range speakers the sub won't need to amplify 'higher' frequencies (120Hz+) like a sat. and sub combo. go with a polk. go with a velodyne. go with anything really because in your setup a sub is only going to amplify a narrow band. try getting a sub with both a LFE and speaker level inputs. try them both out and see which sounds best in your environment.

[OldmanSRS]

Impedance value varies with the frequency. Speaker impedance is usually rated as "nominal impedance" meaning it's kind of sorta around the stated value most of the time but not really. It usually spikes way up at the XO points and is lowest in the lower frequencies.

When using a sub, phasing is important so it does not cancel bass produced by the PR in the 10's. XO point is important so you get a smooth transition of the PR to the sub. Placement is important to prevent standing waves the can add or or subtract the bass at your listening position.

I bought an HSU VTF-3 some years ago. Very pleased with the HSU products. When used with the 10's and the CRS+'s, it makes a formidable 2ch setup.

[Anthony Hinton]

I agree with the add a sub crowd, any decent powered sub would make a world of difference.

[cowtrimmer]

Your probem isn't the 10s per se or the size of your room. The receiver you're using is only rated for 8 and 6 ohms. The 10s are 4 ohm speakers. You're not supplying them with sufficient power especially if your musical tastes include heavy bass tracks.

Even though the specs of the monitor10 speakers state they are 8 Ohm speakers they are actually 4 ? The reason I ask is because I was thinking of buying a pair, but may have to rethink this based on not having enough to drive them now.

[jeremymarcinko]

That onkyo in your sig will be just fine.The monitor 10's are just as efficient as those 70's. More power usually sounds better but I used a onkyo705 with my 10's for a while. I eventually added a amp but the onkyo was definitely sufficient and nice warm sound.

[cowtrimmer]

I wasnt going to use the Onkyo but use an old Scott receiver I had and make more of a display-vintage looking system and park it next to an old Coronado 6 tube short wave radio my Grandmother had given to me years ago.

[84shovelhead]

Hi have a set of 10's I bought new in '80 and recently added a polk psw 1000 from a guy on here that sells them with a 500 watt bash amp.In my setup this sub blended in perfectly and can really hit if you want-thogh I am not intothe unatural thump that some may prefer.Amp is a mitsubishi dar15 150 wpc dual mono construction as is the pre-amp.room size 14x30 with a large opening on one side,9plus foot ceilings ceramic floor.am loving the sound from this old "crap" and the look I get fromm friends who hear it!Almost as much fun as ripping it up on a bike!

[jimsvm]

More questions about 10s . Would the efficiency of speaker change with the new cross overs? Second, would the resistance change.? Thanks,

[westmassguy]

More questions about 10s . Would the efficiency of speaker change with the new cross overs? Second, would the resistance change.? Thanks,

No on both counts

[StantonZ]

Even though the specs of the monitor10 speakers state they are 8 Ohm speakers they are actually 4 ? The reason I ask is because I was thinking of buying a pair, but may have to rethink this based on not having enough to drive them now.

I wouldn't tell someone NOT to get a pair of Polks just because of impedance concerns, because it may not be a problem for you depending on what kind and how loud you listen to your music. However, if you like your music REALLY loud, you may want to re-consider your source of amplification.

[shawnszj]

Hi guys, I've been doing a lot of reading on the forum but this is my first post.
In regards to impedance of the 10s I bought a pair and a pair of 7s and a pair of m20 based on the fact that the Polk site rated them as 8ohm. For some reason I decided to put my fluke meter on them and test for resistance. Result 4ohm for both 10s and 7s. And 8ohm for the m20. Now I have a problem my receiver Yamaha RX V1900 manual says I can only use 4ohm on fronts and either 6ohm or 8ohm anywhere. I wanted to use the 7s in zone 2 or as surrounds, and the m20 as surrounds. Question if I use the 7s I'm I going to damage my amp? I like my music loud.
Confused

[jeremymarcinko]

It will be just fine, don't drive them to a clipping situation, otherwise enjoy

[canadianicon25]

Result 4ohm for both 10s and 7s.

Were your measurements taken directly from the speaker or did you connect your multimeter to the terminals on the back. To measure the DC resistance of the speaker you need to connect directly to the back of the speaker driver itself.

Another thing to note is impedance is an AC measurement not DC. Typically the resistance measurement on a multimeter is DC and a meter will not measure AC impedance.

Impedance is calculated by the following:

Z=R+jX where r= DC resistance and X= capacitive reactance - inductive reactance. You may want to google these topics. It gets somewhat mathy and requires knowledge of complex numbers.

[shawnszj]

Were your measurements taken directly from the speaker or did you connect your multimeter to the terminals on the back. To measure the DC resistance of the speaker you need to connect directly to the back of the speaker driver itself.



I took the measurement at the main terminals. (Where it matters for the amp) the amp doesn't connect to each driver separately. I do and have done some really large car audio setups, multi amps, 1,2,4ohm setups. I understand that each speaker is 8ohm but the way they are run in series reduces impedance at main terminals to 4ohm. I don't care about the math. In car audio if I ran a 2ohm load on a 4ohm amp, damage could and would happen. I'm just not sure about the effects of home audio (AC) hmmm impedance is AC I find that interesting think I will Google that.
Thanks