Help me update my Merlin crossover please

[Kip]

Here is a schematic of my Merlin VSM-m's crossover. Please comment on any upgrades I can make.

The soldering of the crossover parts is very poor, and there isn't any mechanical contact for the components, only solder. I noticed that some of the strands on the caps leads were cut making a smaller gage wire, I assume durring stripping. The large 2.25mh inductor is connected to the caps and woofer wire lead via a solder joint.

I am not looking to change the values of crossover points, just the quality of components. IMHO I think the Caddok resistors and the Hovland caps are good, but the woofer inductor, I would like to upgrade. Please comment.

[Kip]

No comments on upgrades of components? When I post questions in the digital forum, I get comments.

I built North Creek Rhythm speakers years ago, have a slew of Dynaudio drivers and a electrostatic double impact kit that I did not finish yet. I designed a few small first order crossovers and boxes for the dynaudio drivers and decided to purchase a used set of Merlins to play with. I took apart the Merlin VSM-m to do some updates, post the info here for help and get no advise. Maybe nobody knows.

On the digital forum, some are designing their own dacs and some are updating consumer or retail versions. I assumed that purchasing a pair of used speakers, for much less then new, and updating the small parts count crossovers would be normal practice on the loudspeaker forum too.

[sreten]

Hi,

One mans upgrade is another mans waste of money.

Hovland 16ga inductors doesn't sound too shabby, but what is
a 0.8R resistor doing in series with a 16ga treble inductor ?

Could change this to a 1R air cored inductor, delete the resistor.

Bass inductor, want to go lower DCR or go air-cored ?

/sreten.

[Kip]

Thank you sreten,

I don't know why the .80ohm resistor is there, maybe to try to pull down the tweeter some more. Are you saying I should replace the inductor and resistor with an inductor with the same value as the current, but find an air cored version that has .8ohms more resistance?

I want to change the bass laminated core inductor to air cored. My thought was, if I replaced the current 2.25mh inductor with a North Creek 12ga air cored inductor the DCR will be very close. I would then be able to make the leads on the new inductor long enough to connect the input terminal and the speaker without any other cabling and eliminate an extra solder joint too. I would, of course, scrape the lead after the new inductor to tie in the caps.

[stokessd]

I don't like the idea of an iron core inductor on the treble circuit. I'd measure the DCR of the original and an air core one and adjust the 0.8 ohm resistor accordingly. I'd keep the iron core inductor in the bass leg, as the lower DCR of the iron will help you on the bass.

But you know what they say about opinions.

So why are you bunched up about the solder connections? I realize it's not ideal, but in the grand scheme of things, I suspect it's pretty far down there on the list of things that matter in your system.

Sheldon

[Kip]

Mechanical connections are always best. Solder is never as good as a good old crimp or nut. If you look at most speaker connections, the ends are crimped, not soldered. I did government work for years, years ago, and they always wanted a good mechanical connection before it was soldered.

[sreten]

Hi,

The simple fact is if you've got 0.8R in series with an inductor, using
heavy gauge wire is utterly pointless, I suspect the 0.8R is a later
"improvement" and possibly they kept the advertising blurb of
"low loss" inductors so kept the "low loss" treble inductor.

Go air-cored by all means if you think it will be worth it. The treble
inductor should be fairly cheap as you can adjust the series resistor.

The bass inductors ? $60 a pop. But note just because they are
air-cored doesn't mean you don't have iron in the circuit, after
all the voice coil is in an iron magnetic circuit.

The "improved" "SE" version used a lower DCR cored coil than standard.

/sreten.

[Kip]

I would like to know what Merlin did to update from the -M to the -MM?

I did read that Merlin did a change to a lower DCR coil. My guess is they went from a iron core to this laminated core, wich I believe is better, but I think and aire core inductor is better yet.

I agree that the advertising demanded the added resistor in the tweeter circuit. They probably updated the coil to the laminated one and needed to add the resistor because of the newer coils lower DCR.

[stokessd]

Originally posted by Kip
Mechanical connections are always best. Solder is never as good as a good old crimp or nut. If you look at most speaker connections, the ends are crimped, not soldered. I did government work for years, years ago, and they always wanted a good mechanical connection before it was soldered.

Right, in an ideal world, you would have good mechanical contact then soldered. But I'll take poor contact and solder vs. just a crimp with no solder any day. Look at reference transducers like platinum resistance elements for lab use. The spade lugs are ALWAYS soldered. That's an application that the contact resistance can't change.

[stokessd]

Think carefully before switching the woofer circuit to air core. That 2.25 mH is a lot of wire and the DCR will be a lot higher than the iron core you're using. You can play games by using an air core with much heavier wire, but the size goes up significantly.

Sheldon