Guess I'm in dense mode at the moment cause I'm still confused. Is the current plot for a stock M7 lined or stuffed with polyester? Next data point will be stuffed with FG? Comparing the recent plot with the one you linked I don't see much of a difference.
Minimus 7 Loudspeakers - Measurements
- Thread starter Zilch
- Start date
Guess I'm in dense mode at the moment cause I'm still confused. Is the current plot for a stock M7 lined or stuffed with polyester? Next data point will be stuffed with FG? Comparing the recent plot with the one you linked I don't see much of a difference.
Earlier in the thread, I removed the crossover and input terminal assembly from the experimental Minimus 7, and replaced it with a small piece of 1/8" fiberboard with the driver leads running through it so as to be able to evaluate the various crossover circuits situated externally. I left the stock internal damping in place.
Two questions arise:
1) Would the performance be altered if the crossover components for the preferred mod were mounted inside, i.e., would it be worthwhile considering external mounting in order to preserve any advantage which might have occurred as a consequence of "emptying" the box? Answer: there is no such advantage.
2) Is the "empty" experimental Minimus 7 performing differently from how it did as a stock unit? Answer: Not that I can see by examining the baseline measurements of four units. In fact, there would appear to be less variation in the test uint, stuffed vs. empty, than among several stock ones.
The issue is moot.... :yes:
I think I get it now: Stuffed = xover components internal to box, not box stuffed with damping material.
Unless something untoward arises while installing the mod in multiple units here, I'm done.
Whether it's "optimum" or not, I don't know, but by my standards, it's better than anything else anyone did over the last 30 years.
If nothing else, that's all documented here, and you're $30 away from making your own determination as to whether what I've done is worth a whit.... :yes:
Hey Zilch....
I've been trying to keep track of this thread, and I just can't get through a lot of the highly technical stuff. I got lost at the 7 different mods section....
Any chance that you could make a single post that encompass just the mod, and the graphs pertaining to it....I think it would be a lot easier for us not-so-technical folk out there.
I've been trying to keep track of this thread, and I just can't get through a lot of the highly technical stuff. I got lost at the 7 different mods section....
Any chance that you could make a single post that encompass just the mod, and the graphs pertaining to it....I think it would be a lot easier for us not-so-technical folk out there.
Elfasto
Super Member
In a Nutshell...
Stock speaker, stock parts:
Same speaker, with Zilch's PZ-2.1 crossover:
Basically the new crossover flattens out the frequency response above 400 Hz all the way up to 20K or so. Makes the speaker much more accurate sound-wise than the stock crossover, which is simply a capacitor and inductor.
The PZ-2.1 crossover:
Again kudo's to Zilch and Pete for their hard work.:thmbsp::thmbsp:
Stock speaker, stock parts:
Same speaker, with Zilch's PZ-2.1 crossover:
Basically the new crossover flattens out the frequency response above 400 Hz all the way up to 20K or so. Makes the speaker much more accurate sound-wise than the stock crossover, which is simply a capacitor and inductor.
The PZ-2.1 crossover:
Again kudo's to Zilch and Pete for their hard work.:thmbsp::thmbsp:
Last edited:
YES! Kudos to Zilch! I'm anxious to get a pair and do the before and after comparisons.
Here's the thread where the Sonance tweeter is mentioned, and a few more mods are mentioned. I believe that the PB-1 and PZ mods here are better:
http://www.diyaudio.com/forums/showthread.php?threadid=107075
http://www.diyaudio.com/forums/showthread.php?threadid=107075
Glad I already have several of these Minimus and re-badged 7's to mod and enjoy. The world of M7 owners and enthusiasts is increasingly finding this thread. Now that it's clear how much gooder this good little speaker can be, it will be interesting to see if and how that impacts it's availability in the used market.
We might even see stock depletion's of the crossover mod parts that ... I ... haven't ... yet ... ord .....
'scuze me -- gotta run!!
We might even see stock depletion's of the crossover mod parts that ... I ... haven't ... yet ... ord .....
'scuze me -- gotta run!!
tylerdurden
Active Member
What a great thread!! Thank you Zilch and everyone else who worked on this. I havnt visited AK in a while and am sorry I missed this. I have been intrigued with the little speaker for awhile now. (ever sinse a pair fell out of a box spring matress that was left in an apartment I moved while doing building maintenance. The guy bailed on his rent)
Anyways the cabs where severely dented and rusty, missing the grills. But they sounded great. I liked them so much that I now own three pairs of mini 7w's.
But this is what I am doing with the drivers from the metal cab (free) versions I scored on:
Putting them in a larger cab
And changing the baffle arrangement
I am using the Ebay Mod on the xover. with two exceptions, I am using an iron core inductor of the same value (.5mh) on the woofer and a small iron core of the same (stock) value on the tweater. I have no idea what this will sound like and after reading threw this thread, my plan may be flawed. Specially with the iron core on the tweater.
It has been my opinion that the single most limiting factor for these drivers is the cabinets. But that is what makes the minimus 7's what they are. And you guys have improved on them in every way. I will be putting together another set of xovers as per the specs here and using the larger inductor. Thanks again guys! Great work!
Bobby
Anyways the cabs where severely dented and rusty, missing the grills. But they sounded great. I liked them so much that I now own three pairs of mini 7w's.
But this is what I am doing with the drivers from the metal cab (free) versions I scored on:
Putting them in a larger cab
And changing the baffle arrangement
I am using the Ebay Mod on the xover. with two exceptions, I am using an iron core inductor of the same value (.5mh) on the woofer and a small iron core of the same (stock) value on the tweater. I have no idea what this will sound like and after reading threw this thread, my plan may be flawed. Specially with the iron core on the tweater.
It has been my opinion that the single most limiting factor for these drivers is the cabinets. But that is what makes the minimus 7's what they are. And you guys have improved on them in every way. I will be putting together another set of xovers as per the specs here and using the larger inductor. Thanks again guys! Great work!
Bobby
skywave-rider
Slumming in Akihabara
Parts ordered, yay!
Inquiry:
http://audiokarma.org/forums/showthread.php?t=207100
Response:
O.K., so how 'bout if we invert the tweeter polarity:
http://audiokarma.org/forums/showthread.php?t=207100
Response:
O.K., so how 'bout if we invert the tweeter polarity:
Attachments
skywave-rider
Slumming in Akihabara
Hmmm. I was hoping to get everything onto the plastic plate, but your mockup says no. Maybe drill through the box to mount the 1mH coil? Then goop over the other components on the terminal plate. Nice and neat, though.
:scratch2:
Am I feelin' lucky?
Using lots of glue holding them in place? I'd glue them to the bottom, over an insulator of some sort so as not to short anything out when you stuff the thing full of pink FG.
Ever test the current RS version of this speaker? I think there is one still made, but it's ported and up here they're called 'Centrios' or something....
tylerdurden
Active Member
I do know of a similar speaker to the mini 7's called the Optimus pro44's. They use similar drivers as the 7's, except they are sheilded and the cabinet, wich is exactly the same, is ported. The drivers where made in Malaysia. From the exterior they look like Metal cab 7's, same size, everything except the port.
You can sometimes pick them up for alot less then the 7's, as they are not as popular. Maybe thats what your thinking of Packrat.
You can sometimes pick them up for alot less then the 7's, as they are not as popular. Maybe thats what your thinking of Packrat.
The easiest solution is replace the input terminal plastic plate with a single board having all of the components on it and quality input binding posts, which some may want to do anyway. We have two secure mounting points for the board, but I'd still be looking for additional support for the 1 mH coil.
You'll likely lose the stock 0.4 mH air-core coil in doing that, so it moves the cost of the mod and upgrade into the $50 region. I may do that on the second pair here, but for now, I'm trying to work with what's there.
This is quite a good layout from a connection perspective, as well, as I'll show in the next step. A board version would likely be similar.... :yes:
I'm certainly tempted to gob them up with glue, but being able to restore them to stock is always a priority consideration when working with quality vintage gear....Using lots of glue holding them in place? I'd glue them to the bottom, over an insulator of some sort so as not to short anything out when you stuff the thing full of pink FG.
