Aerius active crossover and more project

[SHKnapp]

I'm just getting started on reconditioning and upgrading my first pair of Martin Logan speakers. I bought them used in 1999. Up until a few months ago I was using them as rears in a 5.1 setup. I was going to sell them, but I decided I wanted a vintage 2ch setu... I always wanted to run them with tubes. I decided to shower the panels, so I took them apart. My current plan is to bi-amp them. One Marantz 8b as a monoblock for each speakers panel and a Marantz 300DC in stereo for each woofer. I'd like to bypass the passive crossover to get the most out of the amps.

Recommendation on active crossovers? Analogue or digital?
Should I do a woofer upgrade while I'm in there?
Any other mods I should consider?

Thanks for the help... I'll post pics of my progress!
Spencer

 

[JonFo]

Nice sounding project there Spencer. I'll definitely be in the cheering section as you go through this one.

On crossovers, I've tried them all, and can categorically state that a good DSP-based unit is the way to go, as you will need to tweak a lot to get the panel / woofer / room blend just right.

The unit I recommend you look very closely at is the DBX DriveRack Venu360 as it is a an incredibly reliable unit, super clean sounding and has all the features (and more) that you need for this project.
I've been using various DriveRacks for 16 years and they are complete workhorses and totally silent. My 4800 has been constantly on for 9 years now.

Definitely do a woofer upgrade, as with an active xover and bi-amping you can tune the woofer independently and have no need to match existing speaker parameters. Your only concern is to match the box size ( 1.25 cubic foot sealed enclosure ) and to pick a unit that has excellent performance up into the 500Hz range, ideally flat to 800Hz or beyond. A low moving mass spec is also desirable to allow for a cleaner impulse response in the 500Hz range, which is around where your crossover point will likely be.

You can take a read through my SL3XC center channel build for an idea of the changes required to the step-up / crossover board. In your case, do keep the 1-ohm load on the feed to the panel, as not sure how that Marantz would deal with the raw step-up transformer / ESL load (impedance goes down to 2 ohms)

Looking forward to hearing / seeing your project come to fruition.

 

[SHKnapp]

Jonathan... WOW!

What an amazing project. I hope my little project is half as successful as yours. Having you as a cheerleader will certainly help!

Just watched a few promo videos for the DBX DriveRack Venu360. Looks like a great piece of kit. I had been contemplating a miniDSP DDRC-24. Partly because I could start with the miniDSP 2x4HD at a low price point and software upgrade to add room correction later. It's also small... I'll be hiding whatever I use as an active crossover because this will all be for my lounge setup that is all vintage silver face gear. The issue I've read about the miniDSP is that they don't usually play well with pre-amp volume controls. Sounds like most people recommend using the digital volume control that only accessible through the remote... there's no remote in this vintage setup! I don't imagine you have any issues with using your Meridian volume control in conjunction with the DriveRack.

 

[Tosh]

If you wanted to keep things a lot simpler, then you could use an analog active xo for only the bass, while leaving the passive xo and eq alone for the ESL. But that's easier said than done, because there are no cheap analog 12dB/oct active xo's on the market. Maybe the closest is the Rolls SX45 for $100?
http://www.parts-express.com/rolls-sx45-stereo-two-way-mini-crossover-w-sub-output--245-1184

 

[SHKnapp]

I've been making some progress!

Took Jonathan's advice and ordered the dbx driverack venu360

Ordered new woofers ScanSpeak 22W/4534G00

Washed the panels... anyone ever have their panels separate at the sides? One of my panels seems to be delaminating. The front was separating from the back before washing. They are staying together mostly because of the clear tape on the top and bottom of the panel.

 

[SHKnapp]

Not original double stick tape on stators and missing Velcro. Guess these have been worked on at least once.

 

[SHKnapp]

Looks like more non-standard black spacer tape.

 

[SHKnapp]

Back panel removal

 

[SHKnapp]

Rails getting painted to match the white component rack

 

[JonFo]

Nice progress, do keep us posted on how it goes.

 

[SHKnapp]

I got all the easy stuff done!
Showered panels
Filled in woofer cutout to accommodate slightly larger woofer mount
Repaired dings in cabinets
Repaired dings in rails
Painted cabinets matte black
Painted rails gloss white
Replaced binding posts on one of the boards. (Keeping one untouched to use as reference until I get the one fully up and running)

 

[SHKnapp]

Sorry about that sideways pic.

 

[SHKnapp]

Where I could really use some help is with the ESL crossover bypass. Jonathan, I've studied the schematic for your rebuild but the differences between the wiring on my Aerius are just enough to confuse me. I've got the schematic for the Aerius from ML and I can provide any necessary pics from mine. I've got the resistors to create the 1-ohm load, I just need to know where to insert them and what other connections need to get changed to bypass the crossover.

Let me know what pics I should post so someone can help me with the wiring.

Thanks!
Spencer

 

[JonFo]

Congrats on the progress Spencer, looking good.

Do post the schematic and a pic, then I should be able to point out how to bypass.

Basically, where the current crossover circuit feeds the step-up transformer, you want to remove everything between that and the red (signal) post and replace it with just the input from the red post, go through the resistors and then into the step-up.
The feed for signal and ground to the music sense input of the high-voltage remain, as does the ground (black post) feed to the high-voltage board. The negative side of the step-up us also fed from the black post.

The bass crossover is totally removed. You hardwire the posts to the low-frequency driver terminals. Remember to remove the bridging clips between the panel and woofer input posts.

 

[SHKnapp]

Here's the schematic that Martin Logan gave me. I'm guessing this is everything that needs to get bypassed so maybe this isn't that helpful

 

[SHKnapp]

Here's the full board

 

[SHKnapp]

Grey Music Sensor wires... leave these alone.

 

[SHKnapp]

Yellow signal wire going directly to passive crossover?
Then out of the passive crossover to the step up transformer?

 

[SHKnapp]

The ground is a lot more confusing to me. It starts at the binding post


and then branchs here



One of those goes to the step up transformer?

 

[SHKnapp]

Another branch goes through some coils?, capacitors? and resistors? and connects thru a resistor? to something that the signal is connected to?



I can post more detailed photos of this path if it's important.