RD0-194 for Monitor 7C

adam2434

I've been using a pair of 7C's in my garage for a while.

The SL2000 tweeters sound a bit dull and lifeless - lacking in resolution/detail and providing a warm overall tonal balance.

I know folks have described the S2000 as harsh or edgy, but I'm not hearing that.

I had the same impressions when I used them in an unfinished part of our basement.

So, I'm wondering if the RDO-194 replacement will add some life to the presentation, in terms of detail and resolution?

Adjusting toe-in and angle of the speakers has helped a bit, but I would be willing to invest in RDO-194, assuming they could liven-up things a bit.

pitdogg2

The rdo-194 is a much better tweeter, only your ears can say weather or not its an upgrade. Most of us here prefer the 194.

cortico

Hi, I wouldn't describe the SL2000 as dull and lifeless, I think that it's actually the opposite. Check if the symptoms you're complaining do not have it's origin in the amp...

I have switched the SL2000 with RDO194 and they sound smoother than the originals.

F1nut

If you have the original caps in the crossovers they are way, way past their prime and likely the cause of the dull sound because the SL2000 is anything but.

westmassguy

If you plan to keep the crossovers as-is, then the RDO-194-1s are drop-in replacements. As F1nut stated, the crossover components are well past their prime, and the quality of the original parts wasn't great. If you intend to upgrade the crossovers, I'd recommend doing the SL3000/TL modification, and use Polk's RDO-198-1 Tweeters. The 194s are a vast improvement over the SL2000s, and the 198 are even better.

adam2434

Thanks for the replies.

The amp (Rotel RB-1582 MKII) is not the issue, as I also use it with my LS90's in the main media room.

My reference speakers are the LS90's, which are much more detailed in the highs.

The old caps could certainly be a contributor, combined with the fact that the LS90's could just be a more detailed reference for comparison.

Years ago, I read something here regarding the SL2000 not aging gracefully, or something to that effect. So I was thinking that perhaps the SL2000's response may have degraded, and that 194 replacements could bring back some sparkle and detail.

westmassguy

The LS90s are great speakers, however the Monitor 7s are no slouch. When fully upgraded, they're quite formidable. Monitor 7s are the sweet spot in the entire vintage monitor line.

adam2434

I have a 7C crossover schematic. It’s a little blurry, but looks like there is a 12uf mylar in series with the tweeter and a 34uf electrolytic in parallel with the woofer.

The 12uf mylar is the one impacting the tweeter output, right? I didn’t think that mylar caps degraded like electrolytics do.

Also, would the 34uf electrolytic have any impact on the tweeter?

westmassguy

Mylars don't age, but do sound like crap, and are usually shunted with a silver mica cap. The 34uf shunt cap doesn't affect the Tweeter, but will affect the voicing of the Woofer which handles a lot of the vocals, and bass of course.

leftwinger57

I have had minor experience w/ all 3 tweeters. The Sl 2000s came w/ my '87 2Bs and were tarnished, high pitched and a bit scratchy.They were replaced w/ the RDO-194s and made a huge difference. Now come my '78 M7s w/ original Peerless tweeters which are smooth as silk and I hope they last a long time. If your silver domes really bother you than go for the 194s @$48 each being a club member and all that.

adam2434

To summarize input:

Degradation of the mylar cap is not likely the cause of the somewhat soft treble. (BTW, I was doing some listening last night and noticed that cymbals and piano detail is pushed back in the mix, giving a somewhat muddy tonal balance.)

The RDO-194’s and new/better caps will improve the sound, but may not liven up the sound.

I think I’ll go ahead and order the RDO-194’s anyway and make the cap upgrades a winter project.

Are the RDO-194 connector tabs the same size, or will I need to put different connectors on the wire?

stogie

The SL2000's on my SRS's had the same size tabs as the replacement 194's.

adam2434

Hooked up a single 5A today. Picked up a pair a couple years ago, but one had a funky replacement driver and a damaged PR.

Wow, the Peerless tweeter is so much more detailed and lively compared to the 7C's SL2000's. It sounds fantastic - the high freqs are very engaging and involving compared to the 7C. I'm wondering if my 7C's SL2000's have become tired. They sound muddy compared to the 5A. The 5A does not come close to the 7C in terms of bass extension though.

I ordered a pair of RDO-194's, so I hope they improve the 7C's detail and get closer to the 5A and LS90 presentation. If this does not do the trick, I'll probably update the crossover components.

The 5A vs. 7C difference does have me wondering if the 7C has a naturally darker presentation. For those that have experience with 5's and 7's, are the 5's tonal balance more forward and detailed in the highs?

westmassguy

It's the SL2000s that suck. Once the RDO-194s are installed and broken in, they'll sound much better. The SL2000s have a 5db resonance peak around 12-13KHz, the highs are exaggerated.

boston1450

If your liking the peerless then you will enjoy the RD0's. Well worth the $$$. I still have a pair of 5jr's that have the sl2000's & i use them to test equipment when needed. I dont mind them & sometimes i enjoy them with long listening while working on a project. There are alot here that have had those for years & will argue they are great. I know if someone has issues with 1 of their sl2000's why not upgrade then. It isnt that much money out of pocket. Cant wait to hear your impressions on them

cortico

Rdo is great! But I like the sl2000 too, go figure... I would go forward and proceed with the recap, is just 2 caps and one resistor per speaker!

Did you check the speaker inside? To see how is stuffed?

adam2434

Installed the RDO-194 on Thurs evening and have been running them in since then.

They do sound better than the SL2000. They are more open, detailed, and involving, and seem to have better dispersion too.

The 7C’s are upside-down (tweeters at bottom) on shelves at the upper corners of my garage. They are angled in and down to project towards center of the garage. With the RDO-194, I’m getting a little soundstage depth and almost a center image that I was not getting with the SL2000. The speakers are horribly positioned for soundstage and imaging, so I am pretty surprised to hear changes in those areas with the RDO-194.

While the RDO-194 do sound better, the high frequencies are still pushed back in the mix vs. my LS90 reference. Eric Clapton Unplugged is one recording I use to evaluate equipment. I’ve listened to it so many times that I can easily pick out differences in a speaker’s presentation. I find the LS90 to have the right amount of detail and energy in cymbals, tambourine, acoustic guitars, etc. The 7C are a bit dull and recessed in comparison.

My evaluation is totally subjective and relative. Since the LS90 high frequencies sound “right” to me, I judge other speakers against them. Based on other speakers I’ve owned, the 7C, along with Energy RC-70 and Pioneer FS-52 are less detailed and engaging in the high frequencies. On the other hand, the Polk RTi8 and Athena AS-F2 were too bright and edgy in the high frequencies vs. the LS90. I can live with a less detailed speaker that gives me a “something’s missing” impression, but I can’t live with a bright and edgy speaker.

As a side note, I’ve heard folks make generalizations about metal domes being bright/edgy/fatiguing vs. soft domes. My experience with Energy RC-70 with aluminum domes proves that this generalization is not true. The RC-70 is on the warm and mellow side, never fatiguing even at high volume, and ultimately not as detailed as I prefer. Other the other hand, the Polk RTi8 with silk domes is the brightest and most fatiguing speaker I’ve ever owned. From this, I surmise that the quality of the tweeter and voicing of the speaker are critical, not whether the tweeters are metal or soft dome types.

Back to the 7C…I think I will update the crossovers this winter, since the speakers will get heavy use into the fall. I don’t expect the crossover updates to brighten-up the speakers, but I think it will be a fun and interesting project. I may remove and jumper the polyswitches, which may brighten the highs a bit closer to my liking.

westmassguy

When you compared them with the LS90s, were they at a normal listening position?
The Mylar Caps in the 7s do not do them justice. Put some Sonicaps or Clarity ESAs in there, and the difference will be quite profound. I would not jumper the Polyswitch. Put a .5 ohm, .39 ohm, or .33 ohm Mills 12 watt resistor in there. If you want a more forward, brighter top end, then go with the Claritys.

adam2434

The LS90s are in the main listening room in the fished part of the basement. I’ve tested all the speakers I mentioned, including the 7C, in the same position in this room. My impressions of the 7C being on the warm side have remained as I have moved them to other rooms (unfinished part of basement and now garage).

Thanks for the crossover advice. Will Dayton caps be a decent upgrade if I don’t want to sink a lot into the crossover parts?

westmassguy

Daytons are made by Bennic. They're pretty grainy, and strictly entry level.

westmassguy

If you want to go conservative, do Clarity PX for the Hi & Lo-Pass

adam2434

Did some searching and can't seem to find a 34uf Clarity PX for the low pass.

How about a 33uf Solen PB, with a 12uf Clarity PX for the high pass?

westmassguy

Use a 15uf and 18uf wired in parallel for the 33uf