Polk Monitor 7 w/ Tube Amp...?

[ivan100000]

Hello Gents--

My system consists of a Fisher 400 CX-2 preamp, a pair of Fairchild 255 mono amps (25 watts each), and a pair of Altec Bolero speakers. I was given the Altecs a few years ago by someone who told me they'd be a vast upgrade from my KLH speakers that needed reconing. Now I'm not an "audiophile" by any means, but the Altecs have always sounded very monotone to me, and the best way to describe the general sound experience without using esoteric adjectives is to say that I keep getting the mental image of my records being played with a rusty nail rather than a diamond-tipped stylus.

Getting to the point of my post, my dad just just mentioned that he still has the pair of (perfect condition) Polk speakers that he'd bought in the early-80s, but he has long since retired them to the basement storage area in favor of some new compact Chinese "Best Buy" specials. Upon further review, it appears that the model is the Monitor 7.

My question for you Polk experts is this: Would the Monitor 7 be compatible with my pair of vintage 25-watt mono tube amps? I don't understand the physics of it so well, but I seem to recall reading that 50s/60s amps work best with 50s/60s speakers, because of an "efficiency" issue whereby newer speakers require higher wattages to drive them. The Monitor 7 seems to get nice reviews for a budget-priced speaker, but do you think it might be a marked upgrade over my lifeless Altecs? I'm trying to determine if it's worth the cost of having them shipped cross-country to me.

Thanks for your consideration.

Ivan

[comfortablycurt]

Welcome to Club Polk!:)


The Monitor 7's would sound great being driven by a pair of 25 watt tube mono's! They're fairly efficient speakers, and don't take a lot of power to sing.

I've got a pair of Monitor 7A's with Peerless tweeters that I absolutely love. IMO you can't get a better speaker for less than $100.

What version of the Monitor 7's are they? Do you have any pictures?

There were several different tweeters used in them over the years...some are more desirable than others, but they all sound great.

[danz1906]

Welcome to the Club!

[AudioGenics]

welcome to club polk.

please post some pictures of your tube equipment ....

[hearingimpared]

Welcome to Club Polk.

[concealer404]

A 25 watt tube amp will be MORE than enough to drive some 7s. :)

Welcome!

[ivan100000]

Hello, and thanks for all of your responses.

I don't have any photos of the speakers yet, but my dad says there's a tag in the upper right corner on the back of each that says "Monitor Series" with a serial number below it on one that reads "7 25295" and on the other "7 25299" ...

Any way to tell what the tweeter might be on the basis of those serial numbers? My dad seems to think he bought them in the 70's, but I'm certain they were purchased @1985.

Ivan

[bluecomet]

Your father had good taste back in the day. Fire up those Monitor 7's and enjoy.

[bluecomet]

If the tweeters are black then they are going to be peerless tweeters and the Monitors would be 7a's or maybe 7B's. It there are not black then take the tweeter out and look to see if it says SL2000 or something else. Also if it is a early Monitor 7 model it will have a fuse on the back of it. If it does not it will be a latter model. Let us know.

[ivan100000]

Update: The tweeters say "Silver Coil Dome" on them...

[george daniel]

Put the tubes on em' and let us know how they sound,,he,he.;)

[bluecomet]

I am going to guess there is no fuse on the back of the speaker near the speaker terminals. Am I correct? They are sounding like Monitor 7C's with the SL2000 tweeters in them. I just sold my set. They are excellent sounding speakers with the proper amp or receiver. Remember what you put into the speakers is what your going to get out of them. Your setup should be fine for these speakers. Put them on stands, they sound better than on the floor. Just my opinion.

[ivan100000]

Hi again--

My initial post was probably tough to follow (sorry..!) but the Polk Monitor 7 speakers in question are 2,500 miles away at my dad's house. I just called & found out the tweeters are the "Silver Coil Dome" type, and I'm fairly sure my dad wouldn't know what to look for if I'd ask him about a fuse on the back.

Judging by your overwhelming positive responses, I'll go ahead and have them shipped out to me. The Altec Boleros will go up on eBay.

Thanks again for everyone's advice. I got a bit nervous when a google search lead me to a Monitor 7 review where the guy said, "Even with my wimpy 60 watts-per-channel receiver, the Polks still sounded great."

Ivan

[comfortablycurt]

Your 25 watt tube amps are going to absolutely smoke a 60 watt receiver. External, dedicated power amps nearly always sound better than a receiver.

The "Silver Coil Dome" tweeters are probably the SL-2000's.

Like Bluecomet said, I'd take a guess at Monitor 7C's.

There are a bunch of mod's out there for the 7's as well that you can perform later on down the road. Polk has a direct replacement tweeter for the SL-2000, the RD0-194-1, which is an even better sounding tweeter.

The caps and resistors in the crossovers also get worn out, and fall out of spec over time. Many people have updated their tired out crossovers with newer, better components and had BIG improvements. Depending on your choice of components, this can be done fairly cheap. I'm planning on updating the crossovers in my 7A's next year. No need to upgrade tweeters in mine though, since mine have the Peerless tweeters.:)

One test that you should perform when you receive the speakers is to check for air tightness. The vintage Monitors and SDA's used Passive Radiators for the low frequencies, instead of active drivers. The passive radiators are driven off of the back pressure of the mid-woofers. Because of this, the cabinets need to be air tight.

Push in on the passive radiators and hold them. The mid-woofers should extend completely, and stay fully extended for 2-3 seconds, then start moving back in slowly over a period of 10-15 seconds. If they move in too fast, this means you've got some air leaks and will need to replace the gaskets.

There are many other mods that can be done too, such as replacing the factory gaskets with Mortite, applying Dynamat Xtreme to the backs of the baskets to eliminate ringing, and updating the binding posts and internal wiring.

[ivan100000]

Where might one find the RD0-194-1 replacement tweeter? I was curious to check it out and see the price, but I can't seem to locate any sales info for it.

[ivan100000]

Now I'm thoroughly confused...

http://cgi.ebay.com/Polk-Audio-Tweeter-fully-tested-Peerless-Excellent_W0QQitemZ300335573385QQcmdZViewItemQQptZ Speakers_Subwoofers?hash=item45ed652989&_trksid=p3286.m20.l1116#ht_1764wt_702

There's an auction on eBay for a "Polk Audio Tweeter/Peerless," and the ad goes on to describe it as a Polk Audio SL-2000 Peerless tweeter. I was under the impression that the SL-2000 and the Peerless were two distinct tweeters.

[kcoc321]

Where might one find the RD0-194-1 replacement tweeter? I was curious to check it out and see the price, but I can't seem to locate any sales info for it.

they do come up FS once in a while, but for the most part they are available from PA CS. They run around $46 if you tell them you are a CP member.

[kcoc321]

Now I'm thoroughly confused...

http://cgi.ebay.com/Polk-Audio-Tweeter-fully-tested-Peerless-Excellent_W0QQitemZ300335573385QQcmdZViewItemQQptZ Speakers_Subwoofers?hash=item45ed652989&_trksid=p3286.m20.l1116#ht_1764wt_702

There's an auction on eBay for a "Polk Audio Tweeter/Peerless," and the ad goes on to describe it as a Polk Audio SL-2000 Peerless tweeter. I was under the impression that the SL-2000 and the Peerless were two distinct tweeters.

the SL-2000 and the Peerless ARE distinctly different tweeters.
Don't let some ebay dis-information throw you...hehe

[comfortablycurt]

Those are definitely SL-2000's. Here's a picture of a Peerless tweeter.

http://i715.photobucket.com/albums/ww160/comfortably_curt/peerless_2.jpg


That's the American Peerless tweeter. There's also the Denmark Peerless, which looks exactly the same, but it doesn't have the small hole in the center of the dome.

Polk put the holes in the dome because it supposedly relieves tension across the dome, and gives them a slightly smoother sound.

I've never compared the two, but I wouldn't mind picking up a pair of Denmark Peerless sometime to compare.





Regarding the RD0-194-1's...Call the number at the top right of this screen. Tell them that you need a pair of RD0-194-1's, and be sure to mention that you're a member of Club Polk, for a discount.

IIRC, they cost $48 a piece, the discount basically equates to free shipping.

[ivan100000]

Thanks Curt--

$100 is a bit steep for me. Worth the money for the upgrade in your opinion?

[george daniel]

Now I'm thoroughly confused...

http://cgi.ebay.com/Polk-Audio-Tweeter-fully-tested-Peerless-Excellent_W0QQitemZ300335573385QQcmdZViewItemQQptZ Speakers_Subwoofers?hash=item45ed652989&_trksid=p3286.m20.l1116#ht_1764wt_702

There's an auction on eBay for a "Polk Audio Tweeter/Peerless," and the ad goes on to describe it as a Polk Audio SL-2000 Peerless tweeter. I was under the impression that the SL-2000 and the Peerless were two distinct tweeters.

The e-bay speaker is not a Peerless,, buy the RDO replacements,hook em' up to the tube amps,,you can thank us all later,,you gotta' trust us on this one.;)

[concealer404]

Thanks Curt--

$100 is a bit steep for me. Worth the money for the upgrade in your opinion?

YES!

The SL2000 is a pretty harsh tweeter and has a nasty spike in db on particular frequencies up top. If you're used to it, you may not "know" any better, but once you hear the RDO, you'll realize what you've been missing.

I'm replacing with RDO as soon as i possibly can on mine. :)

[bluecomet]

You will hear the difference between the sl2000's and the peerless tweets at higher volume levels. The RDO's are worth it. I replaced sl2000 in my SDA SRS 2's and it was a huge improvement. The one thing strange about the sl2000 is that some of these tweets hold up better for what ever reason than others. Meaning I have heard Sl2000's from the same time period when one sounded decent and the other aweful. So when you get the speakers listen to them and if they sound good keep them for awhile. If you like to crank the speakers up and you have the gear to do it then the RDO's are the way to go.

[CVSO915]

I have Polk Monitor 7's with the SL2000 tweeters. They have great synergy with my Yaqin MC-10L Integrated tube amp. Try them without changing tweeters to see how they sound before you spend a couple hundred on tweeters. They sound fantastic with my tube setup. Make sure you put at least 100 hours on those tubes to make a fair assessment of the sound.

[ivan100000]

Does anyone have experience with these?

http://cgi.ebay.com/Peerless-Copy-8-ohm-Tweeter-Replacement-for-Polk-ADS_W0QQitemZ150364380186QQcmdZViewItemQQptZSpeake rs_Subwoofers?hash=item23026a5c1a&_trksid=p3911.c0.m14#ht_546wt_782

[Face]

I believe the crossovers between the original Monitor 7's and SL2000 Monitor 7's may be slightly different.

[kcoc321]

I believe the crossovers between the original Monitor 7's and SL2000 Monitor 7's may be slightly different.

Do you (or anyone else) have 7A's with Peerless tweeters that can confirm the Cap & resistor sizes for these?
The wiring diagrams online here only go back to the "7_orig" with the safety switches, so there must be some "more original" than that. (ie.. ones with fuses)

I have some 7b's that I am considering trying swapping the SL1000's for Peerless tweets, and they match the specs for the "7_orig"
I am going to be redoing the Caps & resisters so it would be nice to know if I need to change the values.

From what I can tell, the "7_rev" only changes the HP inductor to 0.22mH (from 0.23mH)
they both have the 12uF caps.
The Resisters are both shown as 2.0mH (revised from the 2.7mH)
thanks

[jimbo1421]

http://www.polkaudio.com/forums/showthread.php?t=86195&highlight=monitor+7A

This is my thread on refurbishing a pair of Monitor 7As (with fuses). #17 lists my original and replacement caps and resistors. But really you should check the actual crossovers since I understand the parts sometimes changed without notice.

Jim

[madmike]

Does anyone have experience with these?

http://cgi.ebay.com/Peerless-Copy-8-ohm-Tweeter-Replacement-for-Polk-ADS_W0QQitemZ150364380186QQcmdZViewItemQQptZSpeake rs_Subwoofers?hash=item23026a5c1a&_trksid=p3911.c0.m14#ht_546wt_782

I have a pair ordered for a pair of Reynolds Advance A+. I will let everyone know what they are like. I will post my findings at the Possible Peerless substitute? thread

[george daniel]

Good advice,, be sure to get your eyes on those crossovers before you start ordering replacements.

[comfortablycurt]

The Peerless equipped Monitor 7's used a slightly different crossover. They had 2.7 and 4.5 ohm resistors in the signal path, rather than the 2.0 ohm resistor on the SL-2000 equipped Monitor 7's.

As others have said though, you always want to check your own XO's before you order any parts. Polk is infamous for having a lot of variations on various models, and having a lot of transitional models during model changes.

The cutout for the Peerless tweeter is also slightly larger than the SL-2000, and it would have to modified to accommodate the RD0's as well.

IMO, there's absolutely no reason to swap out the Peerless tweets for RD0's anyway. The RD0's sound good, but in my experience the Peerless tweeters sound even better. They just have a natural, smooth, sweet tone that I've never heard out of the RD0-194's in my SDA 2A's.


As far as whether the cost of the replacement tweeters is worth it, I'd say yes. I'd recommend spending some time with them while they still have the SL-2000's first though. That way you get more of a sense of what improvements you're gaining with the RD0's.

[kcoc321]

The Peerless equipped Monitor 7's used a slightly different crossover. They had 2.7 and 4.5 ohm resistors in the signal path, rather than the 2.0 ohm resistor on the SL-2000 equipped Monitor 7's.....
Thanks Curt...do yours have a 4.5Ω vs the 4.7Ω Jimbo's had?

Where in the circuit path are they located? It is hard to tell from the pic Jimbo posted what is the signal path.

FYI: Both my 7b's( with SL1000's) and my 7c's (with SL2000's) have the 2.7Ω resisters. BUT they are both fused, so maybe (?) the change from 2.7Ω to 2.0Ω ( which would include the Peerless) was part of the switch from fused to Polyswitch, since I have read of ppl including a 0.5Ω resister in place of the Polyswitch.

God there sure are a plethora of variants for the 7 Series speakers.

[Crazylitvak]

Tube amps bring out the best in the Monitor 7's. The heart of my system is a Marantz 8B tube amp rated at 30 watts per channel. That's a REAL rating.
I still can't decide whether I like the Monitor 7's or 10's better. The 7's have a better soundstage than the 10's