Will be putting in the new crossover on the RM 40's

zybar · « **on:** 23 Jan 2004, 05:58 pm »

Since I have to repalce the TRT caps in my speakers, it made sense to upgrade the crossovers at the same time.

As the parts haven't arrived yet (will be here later today via UPS), I am not sure how easy or hard this will be.

Big B said the instructions wil be in my goodie package, so I will update everybody later today.

The actual work won't be done until Monday (when a friend + Horsehead will be coming over) so that I can have more qualified and experienced people on hand to do the soldering.

Wish me luck....

GW

Redbone · « **Reply #1 on:** 23 Jan 2004, 06:30 pm »

Hey zybar, I am very interested in the new crossovers and am glad you will get a chance to try them when you replace the caps. It may put a real good face on an otherwise ugly situation. I am guessing that you will have to remove at least one of the 10" woofers to gain access to this stuff. Let me know how that goes. I have read two different methods of pulling the woofers on this forum, neither one sounds too difficult. Good luck !

Q · « **Reply #2 on:** 23 Jan 2004, 08:09 pm »

How kewl is it that VMPS offers continuous upgrades for their speakers?!!!

gotta love it.

Dang I need to order me a pair of these for sure....BUT...I want to hear a review or two about the sonic character of this upgrade! Please post any and all info for us hungry wolves!

zybar · « **Reply #3 on:** 26 Jan 2004, 07:44 pm »

Ok,

The work has been completed and you can see some pics here:

TRT Replacement and Crossover Upgrade Pics

I would like to thank Frank (Horsehead) for coming over along with my great local audio dealer Anthony (www.perrottaconsulting.com). Anthony did all of the soldering and part removal. He did all of this work eventhough he didn't sell me the speakers. Now that is what I call a great dealer!!

Anyway, it was very interesting to see the inside of the speaker (never looks like you think it would). My only big suprise was seeing that the "stuffing" was actual wall insulation. Maybe Brian can comment why he uses this vs other stuffing?

The only problem that happened was that the bottom driver on one speaker had the rubber seal twisted because a little excess was wrapped around the screw. Big B will be sending me another driver and it will be pretty easy to replace.

As for the sound...

That is a little tough since I hadn't logged that many hours before I had the cap issue. Both Frank and myself thought we noticed more vocals coming out of the top 10" driver. Things do sound a little grainy (but that was expeceted since there is a new HF cap and midrange coil in each speaker). Dynamics seem pretty good.

I will basically do what I did when I initially received the speakers and run them via my HT setup non-stop for 3-5 days. At that point I will start to give them a critical listen.

Frank commented how good (outside of the grain) my HT setup sounded on music. The Outlaw pre/pro wasn't the dragon slayer some made it out to be, but it is equal or better than many dedicated preamps costing more than double its price.

Lastly, thanks to Brian and John for getting this all sorted out. At th end of the day, the RM 40's are a special speaker and will be worth the bumpy ride I have taken.

GW

JoshK · « **Reply #4 on:** 26 Jan 2004, 07:54 pm »

Thanks George for the pictures, I still plan to do mine soon but wife says not until after we move.

ekovalsky · « **Reply #5 on:** 26 Jan 2004, 09:31 pm »

Very glad the surgery was successful! Thanks for the pics. I've wondered how they were wired but haven't not had the inclination to open the bad boys up. Here's what I see:

Tweeter: signal > cap > inductor > ground (2nd order ~ 12db/octave)

Midrange: signal > lots of caps

> inductor > ground (2nd order high pass) followed by inductor (first order low pass) *upgrade here*

What's the little yellow thing? Doesn't look like a capacitor...

Woofer: signal > inductor > driver > ground (first order low pass), small coupling cap between binding posts

Anyone have additional observations or corrections?

Horsehead · « **Reply #6 on:** 26 Jan 2004, 10:13 pm »

What's the little yellow thing? Doesn't look like a capacitor...

Here's my guess

http://www.vmpsaudio.com/nf.htm

warnerwh · « **Reply #7 on:** 27 Jan 2004, 12:56 am »

The reason speaker makers use fiberglass insultation is because it's inexpensive and effective. It's been being used for decades. For 75-100 bucks you could buy some acousta-stuf which is supposed to be slightly superior to fiberglass. You wouldn't want to change the damping material without asking Brian though as it would no doubt change other things and fiberglass works fine for damping the backwave and breaking up modes inside the box. Brian may not appreciate this but: If you wanted to add some bracing that may be a worthwhile thing to do though. The box will resonate with the woofer and at some frequencies have output nearly equal to the woofer according to Vance Dickason, a well known speaker guru. It was a worthwhile effort on my ST/R SE's to just add cross braces, midrange and bass are significantly more clear and bass is tighter. Easy to do too. There's a good reason the RM/X has a 6" baffle, thick walls and the cabinet design it does. It's called rigidity.

Horsehead · « **Reply #8 on:** 27 Jan 2004, 03:27 pm »

I'm not sure if the fiberglass Brian uses works to well. The RM40 cabinets, while 240lbs each, have a lot of vibration if one puts your hand on the cabinet. I was getting a pretty bad audible cabinet vibration that required me to remove the top 10" woofer. I suspect there were gaps in the insulation causing the soundwaves to travel directly to the cabinet sidewall causing the audible vibration. I "fluffed' the insulation and moved it around some and the cabinet vibration went away.

Looking at the inside of George's 40s I was not impressed with the workmanship at all (this is no way seems to affect sound quality

) Compared to the insides of my prior Martin Logan Prodigies, the difference was night and day. The inside of George's 40s looked a DIY kit speaker in my opinion. As I said though, in terms of sound quality it does not seems to matter, because my 40s were much better than my Prodigies. I'm just a neat freak and I really appreciate meticulous workmanship. We opened up my Pass Labs D-1 DAC and were mighty impressed with the attention to detail.

George's system was sounding pretty good although there was some further brek-in and tuning that will be required. I also had to leave so it was not a fair evaluation- his tubes amps were just turned on, my DAC was cold and just put in for 5 minutes, etc. George's system is going to sound pretty killer once he gets everything dialed in.

Anyway, it was nice to be a part of the "surgical' team

ekovalsky · « **Reply #9 on:** 27 Jan 2004, 03:34 pm »

Blown cellulose (like I have in my walls) would probably work a lot better than the fiberglass and it is cheap. The entire cabinet would be packed with sound absorbing material and there would be no gaps. Only problem is if "surgery" was ever required, one would have a huge mess on their hands!

zybar · « **Reply #10 on:** 27 Jan 2004, 03:40 pm »

I just started a new thread about ways to improve the 40's... you can find it here:

http://www.audiocircle.com/index.php?topic=7771.msg66305#66305

GW

BrunoB · « **Reply #11 on:** 27 Jan 2004, 03:43 pm »

Quote from: zybar

Ok,

The work has been completed and you can see some pics here:

TRT Replacement and Crossover Upgrade Pics

...

I wonder what the small brown non cylindrical cap on the left of this picture is?

Is it a TRT cap? It looks quite similar to the small caps in my 626R without cap upgrade.

ekovalsky · « **Reply #12 on:** 27 Jan 2004, 04:00 pm »

Quote from: BrunoB

I wonder what the small brown non cylindrical cap on the left of this picture is? Is it a TRT cap? It looks quite similar to the small caps in my 626R without cap upgrade.

Just a cheapo coupling cap I think. There's another across the bass binding posts too.

BrunoB · « **Reply #13 on:** 27 Jan 2004, 04:26 pm »

Quote from: ekovalsky

Quote from: BrunoB

I wonder what the small brown non cylindrical cap on the left of this picture is? Is it a TRT cap? It looks quite similar to the small caps in my 626R without cap upgrade.

Just a cheapo coupling cap I think. There's another across the bass binding posts too.

I can see the the other one across the bass binding post on pict #7.

The small brown cap on pict # 7 and #8 looks like a bypass capacitor for the mid caps. If this is correct, I wonder why one would need a bypass cap for high quality caps such as the TRT's ?

Just curious,

Bruno

Q · « **Reply #14 on:** 27 Jan 2004, 04:30 pm »

Quote from: ekovalsky

Quote from: BrunoB

I wonder what the small brown non cylindrical cap on the left of this picture is? Is it a TRT cap? It looks quite similar to the small caps in my 626R without cap upgrade.

Just a cheapo coupling cap I think. There's another across the bass binding posts too.

Holy crap! is that a iron-core inductor????? I thought those went out of upper end speakers in the '80s!?

For this kinda money, I would think that Alphacore-type foil inductors would be used!...and how about internal wiring? Doesn't look too exotic!!

errivera · « **Reply #15 on:** 27 Jan 2004, 05:55 pm »

Horsehead, I too must agree with your observation. I was actually stunned when I saw the inside of the RM40 speakers. I thought the craftsmanship was of poor quality. I also would have expected that wires would be run more neatly or held in place with wire-ties at least.

One major constructon upgrade I think would serve these speakers well would be the use of T-nuts. That way, problems with the threads loosening over time (because of upgrades or just plain old vibration) would not be an issue.

I have been considering the RM40s for quite some time however, I have not been able to have an audition in the NYC area. I feel strange asking a total stranger to let me audition their speakers in their home.

zybar · « **Reply #16 on:** 27 Jan 2004, 05:59 pm »

Well us audiophiles love to invite strangers into our homes!

I am north of NYC in Carmel NY 10512. Send me a PM and maybe we can arrange a listening session.

GW

Brian Cheney · « **Reply #17 on:** 27 Jan 2004, 06:21 pm »

Before someone gets all incensed, I will point out the following:
I choose all parts based on sound quality. The solid iron core and laminate coils we use sound much, much better than their aircore equivalents due to lower DCR. They have much, much lower stray field that aircores. As for foil coils, they sound awful, with high capacitance causing ringing I don't like.

Point to point hard wiring may look messy but sounds much, much better than a PC board. That's silverplate teflon wire on the mids and trebles and 12 gauge Monster (you can pay extra for Analysis Silver if you want) on the bass. Also selected by comparing with other wire.

Any owner can experiment as he sees fit, but a sideways move is no improvement in my book. There are $100,000pr speakers out there with poorer quality crossovers than the RM40. One maker of such superpremium speakers refused to use TRT's because of their high cost!!!

ekovalsky · « **Reply #18 on:** 27 Jan 2004, 09:07 pm »

I'm just glad Big B has a crossover design that sounds so damn good! Who cares what it looks like? They're not visible (except on the operating table

) and there is no need for a sexy circuit board to photograph for a magazine ad like Thiel used to do.

The TRT caps alone cost more than the entire parts list for a lot of speakers selling in the same range as the RM-40's. Look at the Parts Connexion website and see what big, premium capacitors cost, it is shocking!

At least now I have a little understanding about how the signal is handled once it passes beyond the binding posts...

Working with fiberglass is very unpleasant and continuous exposure is hazardous. B, what do you think of packed (pressure-blown) cellulose? It can be messy but is safe. Or how about the "black hole" stuff used in the G-R research speakers?

Brian Cheney · « **Reply #19 on:** 27 Jan 2004, 09:28 pm »

Cellulose is very frequency selective, foam not reactive enough for LF damping. Cross them off your list.