Martin Logan Vantage Amp board

[m_shiva2003]

One of My Martin Logan Vantage speaker is suddenly stopped working. I can hear only sound from panel but no bass from woofer. I swapped circuit boards from working speaker and found that circuit board "BCFS9LPd" is bad (as shown in the picture). I contacted ML and they mentioned that whole backplate need to be replaced and they are not selling anymore. They said they can repair for $135 PER HOUR plus parts and shipping (no estimated final cost). I can't get it done without having final estimate / worth to fix. Can someone please advise what is the best and reasonable way to fix ?

Thanks in advance

 

[Tosh]

Will ML send you the schematic?
I don't see an amplifier section on that board, just a ton of op amps. Isn't there a class D amp buried in there?
You could ring up Speaker Exchange in Tampa and ask if they know any technicians, but don't just bring it to them. A tech would be able to compare the working board against the failed board, but that's time-consuming with no schematic.
If they were mine I would look into bypassing the internal amp...

 

[wrat]

very disappointing to hear that they are not supplying parts for a less than 20 yr old speaker

 

[Robert D]

I think many will tell you to just bypass the board and use an external amp with crossover to directly connect to the woofer. Something I've never done, but plenty on here have.

 

[baceitc]

Hi, I also have the same martin logan Vantage speaker as yours. My speakers haven't heard for 5 years, now also having trouble with too much bass, I can't hear it, I tried another amp and washed the panel but it didn't get any better.
As for your speakers, I think you should buy them on ebay that sell the same as yours, if possible you can buy replacements for your speaker.
https://www.ebay.co.uk/itm/20414555...LytZpTMQ5W&var=&widget_ver=artemis&media=COPY

 

[Brandon Hartwick]

I think many will tell you to just bypass the board and use an external amp with crossover to directly connect to the woofer. Something I've never done, but plenty on here have.

We suggest this because Martin Logan makes boards that are basically impossible to service, or they just don't carry them anymore. The other thing I'm finding kinda concerning is that when looking at the schematics from various generations of Martin Logan speakers is that most of them are completely different from eachother. From one generation to the next most of the electronics are vastly different, I feel this is going to make some of these speakers very hard to fix in the future.

 

[Robert D]

We suggest this because Martin Logan makes boards that are basically impossible to service, or they just don't carry them anymore. The other thing I'm finding kinda concerning is that when looking at the schematics from various generations of Martin Logan speakers is that most of them are completely different from eachother. From one generation to the next most of the electronics are vastly different, I feel this is going to make some of these speakers very hard to fix in the future.

Then there is the matter that everyone on here that has gone to an external crossover says that the sound is far superior anyhow. I know I would probably go that route.

 

[baceitc]

Then there is the matter that everyone on here that has gone to an external crossover says that the sound is far superior anyhow. I know I would probably go that route.

Can you give me the circuit diagram of the crossover that you say? Thanks!

 

[Brandon Hartwick]

Can you give me the circuit diagram of the crossover that you say? Thanks!

We're talking about using digital electronic crossovers, such as those in the Crown DriveCore series amps. The OEM Martin Logan bass crossovers in the older models were passive and super lossy, the newer models are different (usually digital) but seem to break sometimes and good luck getting new boards.

Check out my thread, it explains everything.
https://www.martinloganowners.com/threads/how-to-active-bass-section.19237/

 

[Robert D]

Can you give me the circuit diagram of the crossover that you say? Thanks!

There are some guys on here with experience doing this. I have not. I just know that they bought external crossover devices. You can buy them from companies and all you have to do is plug in everything. I'm not familiar with what companies are good for this. I remember that prices mentioned seemed very reasonable, so you won't go broke.

 

[JonFo]

I think many will tell you to just bypass the board and use an external amp with crossover to directly connect to the woofer. Something I've never done, but plenty on here have.

Yep, this is the answer.

A $400 Crown DriveCore XLS 1002 will do what the OP needs. It has built-in DSP crossovers and EQ abilities. Simply configure a low-pass at 400Hz using a 24dB/Octave slope. Set volume levels so they match the panel output.
Inside the speaker, disconnect the feed to the driver, and wire that up to some new binding posts for the bass driver. Feed the output of the Crown to this new binding post.
Parts can be found here:
https://www.parts-express.com/search?keywords=binding posts&order=relevance:desc
Extra credit for using REW to measure the system and apply a bit of EQ to match the room (unless you already use Audyssey or another DRC, in which case it will deal with that).

The output of the Pre-amp will need to be split so you can drive the existing amp and the RCA input of the XLS.

Set it up to work with the Vantage that has the blown amp, and once you figure out all the settings. Repeat on the other unit, as that board will soon go.

The Crown amp will last decades.

So for under $500 in parts and materials, you can have better than new Vantages @m_shiva2003

 

[phips1702]

Yep, this is the answer.

A $400 Crown DriveCore XLS 1002 will do what the OP needs. It has built-in DSP crossovers and EQ abilities. Simply configure a low-pass at 400Hz using a 24dB/Octave slope. Set volume levels so they match the panel output.
Inside the speaker, disconnect the feed to the driver, and wire that up to some new binding posts for the bass driver. Feed the output of the Crown to this new binding post.
Parts can be found here:
https://www.parts-express.com/search?keywords=binding posts&order=relevance:desc
Extra credit for using REW to measure the system and apply a bit of EQ to match the room (unless you already use Audyssey or another DRC, in which case it will deal with that).

The output of the Pre-amp will need to be split so you can drive the existing amp and the RCA input of the XLS.

Set it up to work with the Vantage that has the blown amp, and once you figure out all the settings. Repeat on the other unit, as that board will soon go.

The Crown amp will last decades.

So for under $500 in parts and materials, you can have better than new Vantages @m_shiva2003

Hi Jonathan,

I just ran over your post on the substitution of the internal bass amp by an external system, such as the Crown XLS1002. I have a similar issue here with my Spires, the crossover board is defective and ML does not have the boards on stock anymore.
I (think I) understand your explanation on how to wire the external amp to the MLs, but I am using an Octave V40 tube amp that does not have pre-outs, only the regular outputs - is there a way how I still can use your described approach? In principle, the ML approach does the same thing, right? Amp signal goes into the crossover board and the bass frequency is filtered and led towards the Icepower amp, while the mid/high frequencies are led directly to the ESL stage.
Thanks very much in advance for your answer - I was already in fear that I would need consider my Spires an expensive piece of non-functional furniture ;-)
Cheers,
Philipp

 

[JonFo]

I am using an Octave V40 tube amp that does not have pre-outs, only the regular outputs - is there a way how I still can use your described approach?

It would require a speaker to line level converter, such as this one: AudioControl LC2i PRO

Beware of cheap (<$60) adapters, if you want an excellent quality fully passive adapter, the Jensen ISO-Max SP-2SX is the one to get.

The Audio Control is more flexible, as it has selectable load impedance and adjustable output levels.

 

[phips1702]

It would require a speaker to line level converter, such as this one: AudioControl LC2i PRO

Beware of cheap (<$60) adapters, if you want an excellent quality fully passive adapter, the Jensen ISO-Max SP-2SX is the one to get.

The Audio Control is more flexible, as it has selectable load impedance and adjustable output levels.

Hi Jonathan,
thanks very much for your reply. I am still hoping to get the crossover board fixed now that ML supplied me with the schematics, but your option with the Audio Control will be the next one.
Could I somehow split the signal only for the bass driver and let the mid/high frequencies come from my tube amp as they are without going through that line level converter or has that converter no impact on the tube amp sound characteristics?
Cheers,
Philipp

 

[john65b]

The back plane that has two circuitboards in that ebay pic, the upper circuitboard is the ICEPower 200ASC amp board that powers the woofer. The Crossover board below gets power from the ICEpower AUX supply connection... sounds like you swapped the ICEPower boards and confim they both work?

I see no electrolytic caps on the crossover board, so a bit surprised it failed...would have been more expecting the ICEpower board to fail, and fix (replacement) to be relatively simple...

 

[JonFo]

Could I somehow split the signal only for the bass driver and let the mid/high frequencies come from my tube amp as they are without going through that line level converter or has that converter no impact on the tube amp sound characteristics?

No worries, the tube amp will be driving the panels through the existing high-pass passive crossover, as usual.

The adapter simply 'reads' the signal from the amp speaker-level output and generates a line-level signal for the woofer amp. That's it.

So it would flow like this: The speaker output of the octave is wired, as it is now, to the ML speaker (top posts). If present, the bridging straps are removed between the two sets of posts.

A small two-lead wire is also connected to the Octave speaker-level output, and connected to the input of the Audio control. The output of the Audio Control is connected via stereo RCA cable to the RCA connectors on the Crown amp.
The Speaker-level output of the Crown is connected to the lower set of binding posts on the ML.

A modification to the speaker will need to be made, as the lower binding post needs to be re-wired so it directly connects to the woofer terminals.

And the low-pass crossover will need to be configured on the Crown.

 

[phips1702]

Thanks Jonathan, got it!
Btw: my Cambridge Audio N851 has also symmetric outputs - could I just bypass the tube amp for the bass section and go directly into the Crown? The tube amp is connected via the RCA plugs of the N851...

 

[JonFo]

Cambridge Audio N851 has also symmetric outputs

If that is your one and only source, then sure, and even better, use the XLR to feed the Crown Amp. Much simpler than using the adapter.