[kgiesselman]

Needed for project

[Phil A]

Needed for project

There is an old topic here about the non-master speaker - https://www.audiocircle.com/index.php?topic=187750.0  and a link to a YouTube video here - https://www.youtube.com/watch?v=dQ78c-6tH7s


There is also some info here - https://www.diyaudio.com/community/threads/merlin-vsm-crossover-help.362806/   and info that there likely does not seem to be an official crossover schematic here - https://www.google.com/search?sca_esv=4511509f43aa6d52&rlz=1C1HKFL_enUS1204US1204&sxsrf=APpeQnv0OC33dfhL4OTOrxwFI7eSkuXmpg:1788104823196&q=Merlin+vsm+master+original+crossover+schematic+pdf&sa=X&ved=2ahUKEwi5xrrG2ciWAxWyTTABHQOTMagQ1QJ6BAg6EAE&biw=1920&bih=911&dpr=1

[FullRangeMan]

Check with the dealer Rick Brkich at Sigsound.

[Danny Richie]

Needed for project

Why?

The original design did not work very well.

See the upgrade for it: https://gr-research.com/product/merlin-vsm-upgrade-kit/

[kgiesselman]

@Danny,
I think saying the original design didn't work well is a bit harsh and inaccurate. Bobby's original design sounded exactly how he thought it should. I have read quite a bit about the GR Research crossover and wanted to try it without abandoning the original design.

[kgiesselman]

The project has required quite a bit more 'hacking' of the original design than I planned. Getting the original crossover out so that I could get the mid-woofer out required cutting some wires I would have preferred not to cut. Only Bobby P will know how the heck he soldered some of those wires with no slack. Anyway, kudos to Elon, who built a brand-new set of GRR crossovers from scratch, the perfect size to fit through the mid-bass hole and be able to fasten them with four screws set off with plastic spacers to the back inside wall of the cabinet. Elon also picked out some excellent heavy-duty three-position switches (1-0-2) to allow switching between the two crossovers. It is going  to look practically factory when completed.

The actual original crossovers in the speakers do not match any of the schematics I have found on the web or the ones Elon sent (which I assume he got from someone who thought they had the correct crossover design). There are a few more resistors and caps than all the schematics I have found show.

[FullRangeMan]

By what I can see in the photos, too bad Merlin do not paint black inside as some top Euro brands, maybe you could do this improvment now.

Seems this Merlin use the BAM module, that are the extra parts, its a expensive crossover to build.

[Danny Richie]

@Danny,
I think saying the original design didn't work well is a bit harsh and inaccurate. Bobby's original design sounded exactly how he thought it should. I have read quite a bit about the GR Research crossover and wanted to try it without abandoning the original design.

I am not really sure what Bobby was thinking, but to me the big peak at 900Hz and stored energy there made them to harsh to listen to.

See all of the before and after measurements here: https://gr-research.com/product/merlin-vsm-upgrade-kit/

[kgiesselman]

@Danny,
Yes, I watched your YouTube video and read all your documentation about the 900Hz hump. It motivated me to spend a fair chunck of money to purchase your crossover kit, pay to have it assembled into a fully independent crossover that would fit into the lower cabinet in a VSM, install a switch to allow me to A-B the two crossovers, and spend about a week of my time installing the GRR crossovers into the speakers, reconnecting the old VSM designed crossovers and make the whole thing look like it was originally designed with two crossovers.

I don't judge what people like and don't like. A bunch of people paid ~13,000 for a pair of Bobby's speakers, probably more like $30K in today's dollars. It is a bit hard for me to believe they didn't like the way they sounded.

I am sure the GRR-designed crossover will not have the 900hz hump.  I have no idea what that will sound like. I am curious, to say the least.

[kgiesselman]

Which BAM were you running when you measured frequency responses before and after?

[kgiesselman]

By what I can see in the photos, too bad Merlin do not paint black inside as some top Euro brands, maybe you could do this improvment now.

Seems this Merlin use the BAM module, that are the extra parts, its a expensive crossover to build.

Painting the inside is a waste of time when it is full of sound-deadening material. The white you see inside is flocking. Behind the flocking is some form of black rubber mat material glued to the inside walls. Is sound important or Black paint??
BAM were ordered with speakers, not as an add-on.

[Danny Richie]

@Danny,
Yes, I watched your YouTube video and read all your documentation about the 900Hz hump. It motivated me to spend a fair chunck of money to purchase your crossover kit, pay to have it assembled into a fully independent crossover that would fit into the lower cabinet in a VSM, install a switch to allow me to A-B the two crossovers, and spend about a week of my time installing the GRR crossovers into the speakers, reconnecting the old VSM designed crossovers and make the whole thing look like it was originally designed with two crossovers.

I don't judge what people like and don't like. A bunch of people paid ~13,000 for a pair of Bobby's speakers, probably more like $30K in today's dollars. It is a bit hard for me to believe they didn't like the way they sounded.

I am sure the GRR-designed crossover will not have the 900hz hump.  I have no idea what that will sound like. I am curious, to say the least.

In my experience, as soon as you listen to them with our crossover, you will never want to hear them with the ear splitting old crossover again. Every time I heard a pair of them, I was fatigued after just a few minutes of play.

The original had no baffle step compensation. So the whole lower range dropped off and sounded thin. He should have just redesigned the crossover to compensate for the baffle step loss. Instead he sent the signal through a bass boosting device called BAM. Unfortunately the op-amps and power supply used in those things colored everything. So his effort to fix the problem resulted in another.

With our crossover upgrade you can keep the BAM out of the signal path.