Minimus 7 Speakers
- Thread starter Johnny Salam
- Start date
We can certainly do that, but let me get a baseline established first.
I'm going to avoid that, if possible. It was fun trying different drivers in the Presidians, but in the end, they are what they are, and don't warrant substantial upgrade cost.
Murphy himself observes that M7s don't sound as bad as they measure; that's certainly my experience, as well. As he suggests, some of that is doubtless interference between the drivers, and therefore measurement vs. listening location dependent.
We're not going to know what's really up with these until I measure the driver responses individually. Once we have that information, it'll be clear what is possible and practical. I'll post the files, and y'all can tweak away in various crossover modeling software.
The eBay seller makes more of a deal out of the Zobel he added than the Planet10 impedance curve indicates is justified. We may get away with fewer components, actually....
Paratima
E'Wavin'
Here's the schematic, about as big as I can make it. Looks like the parts are "COIL", "7.5uF" and "8 ohms". YMMV
On the other question, have to ask archie2.
PoppaSteve
Your what hurts?
My Minimus 7 story:
I got a white pair from a thrift a couple of months ago. One day they were "speaker of the day" in the family room system I usually set up on my days off.
I believe the amplification that day was my H/K 330B. When my 15 year old son came home from school, he heard them and was all "Wow". Now, he is used to seeing my Imperial 7 and DLK 1 1/2 sets and such set up, so to see these dinky little things must have thrown him for a loop. But he was impressed with the sound, and if you have a 15 year old, you know they aren't impressed much with anything aside from themselves!
I got a white pair from a thrift a couple of months ago. One day they were "speaker of the day" in the family room system I usually set up on my days off.
I believe the amplification that day was my H/K 330B. When my 15 year old son came home from school, he heard them and was all "Wow". Now, he is used to seeing my Imperial 7 and DLK 1 1/2 sets and such set up, so to see these dinky little things must have thrown him for a loop. But he was impressed with the sound, and if you have a 15 year old, you know they aren't impressed much with anything aside from themselves!
TerryO
Super Member
Steve,
I'm sorry that I didn't understand that only crossover concerns were being considered, I guess I missed that part.
As far as you being wary of applying anything to the woofers, that's why I tried to be specific, in order that you would have, hopefully, fairly precise instructions. I may mention that my mod work was originally posted on the old Bass List some years back and was the result of extensive research into cone damping and measured comparisons. It certainly was not the result of haphazard guess work.
Modifications to the woofer's basket, magnet and the cabinet also provide small, but significant improvements. With the exception of the felt applied to the inside of the basket spokes (which is needed, BTW), it is completely reversible.
Your concerns over the volume taken up by the mods and/or crossover capacitors are well founded. However, it's my contention that you need to consider if the additions to the speaker (the mods) improve the sound enough to outweigh the sacrifice in the bass as a result of the reduction in the total volume of the cabinet.
Best Regards,
TerryO
TerryO
Super Member
Steve,
I'm sorry that I didn't understand that only crossover concerns were being considered, I guess I missed that part.
As far as you being wary of applying anything to the woofers, that's why I tried to be specific, in order that you would have, hopefully, fairly precise instructions. I may mention that my mod work was originally posted on the old Bass List some years back and was the result of extensive research into cone damping and measured comparisons. It certainly was not the result of haphazard guess work.
Modifications to the woofer's basket, magnet and the cabinet also provide small, but significant improvements. With the exception of the felt applied to the inside of the basket spokes (which is needed, BTW), it is completely reversible.
Your concerns over the volume taken up by the mods and/or crossover capacitors are well founded. However, it's my contention that you need to consider if the additions to the speaker (the mods) improve the sound enough to outweigh the sacrifice in the bass as a result of the reduction in the total volume of the cabinet.
Best Regards,
TerryO
Cut-Throat
Well-Known Member
I have a pair of Optimus PRO-X55AV - How do these fit into the scheme of the little radio shack speakers.
They are metal cabinets and are very good for their minute size - Only about 7 inches tall.
They are metal cabinets and are very good for their minute size - Only about 7 inches tall.
treserious
Post Punk Junkie
I will be following this closely.
I have a pair of 40-2030B.
if anyone wants, I can crack mine open to determine the driver complement, and the crossover components.
mine have the push button connectors.
with multiple types of these around, and undetermined differences between them, perhaps it would be good to collaborate on getting this information documented.
Pio1980
AK Member
Interesting to note the mini-7 has a fan club. Whoda thunk?
I remember when these things started showing up sometime after ADS began importing importing the Braun metal box series in the mid-70s. I assumed the R/S were basically knock-offs of the smaller Braun/ADS. I thought and still think they all sound "small" regardless, and are pretty inefficient power hogs mainly good only as nearfield speakers. Same for the JBL pro III, FWIW, tho' not a Braun knock-off. The pro III is the best small speaker I've heard disregarding the lumpy bottom end (what little there is).
The earlier AR 2-ways and the Mirage 360 are the physically smallest I've heard that didn't sound "small" as stand-alone speakers. The LS-3/5A wasn't bad but still didn't quite make the cut tho' I used those in a shared overseas Army barracks room for a few years after a full DQ-10+stands+sub outfit was sold in '78. I had my own barracks room and the space for the DQ set-up in the States, good times.
S.B.
I remember when these things started showing up sometime after ADS began importing importing the Braun metal box series in the mid-70s. I assumed the R/S were basically knock-offs of the smaller Braun/ADS. I thought and still think they all sound "small" regardless, and are pretty inefficient power hogs mainly good only as nearfield speakers. Same for the JBL pro III, FWIW, tho' not a Braun knock-off. The pro III is the best small speaker I've heard disregarding the lumpy bottom end (what little there is).
The earlier AR 2-ways and the Mirage 360 are the physically smallest I've heard that didn't sound "small" as stand-alone speakers. The LS-3/5A wasn't bad but still didn't quite make the cut tho' I used those in a shared overseas Army barracks room for a few years after a full DQ-10+stands+sub outfit was sold in '78. I had my own barracks room and the space for the DQ set-up in the States, good times.
S.B.
Brian
An Old Geezer
They were designed for small spaces, and hence nearfield plus being AS by definition will be in the lower efficiency range. They willsound small, just the nature of the beast. As for ADS, I have the L300 and they do sound a whole lot bigger in the same system setups. A big problem of the 7s is while they can handle more power than you'd think they hit apoint where they just can not open up any more. They were designed to a price point and show and sound like it however, they have potential to do somewhat better with some investment of time and parts.
laserman
Ambiguous Optimist
From my source box...
I would like to add a little more info to the back-story of mods.
In the July 1992 edition of Audio Magazine, there was a brief of a mod kit from Soundaid (in NY, NY) for the M7. There was also a review in The Sensible Sound, Vol 10, No. 39. The kit was $29.95 and included two Solen 4.7 uF, 250-V capacitore, cabinet damping sheets of 1/8” thick sheets of material resembling Dynamat w/o any barrier material, a small bottle of Polyvinyl Acetate (PVA) and a small paintbrush to paint the woofer cone.
Instructions from Soundaid:
1. Remove the grill and remove screws holding in the woofer and tweeter.
2. Cut the stock gray cab and leave it on the board since it is hot-melt-glued, solder the new cap to the same stock wires.
3. Carefully coat the woofer cone, let dry for 24 hours and place a second coat.
4. Apply dampening sheets to top, bottom and sides but not the back or front.
5. Replace the fiberglass and woofer and tweeter, making sure all wires clear cabinet openings and then tighten all screws.
6. DO NOT attempt to treat the tweeter dome.
For those who fear coating the woofer will damage it, it did not since I did three pairs and they are fine. [As a side bar, another product to use when coating small paper cones is Grumbacher’s Damar Varnish. I learned about this product from reading about doping drivers and it works very effectively.] Someone mentioned using oil based modeling clay as a good cabinet dampening material. I hadn’t thought about using it but it should do fine and easy to roll out into flat 1/8” sheets. I also like to recommend Mortite’s Rope Caulk or Roof & Gutter instant patch tape would be good products to use. The Roof & Gutter tape is a PITA because it is tar based.
I’m interested in this thread because I still have two NOS pairs that I purchased in the early 90’s that should be modded. The epay one looks interesting but making the project more complicated. Also, I have a pair of Minimus 77’s and there was a mod for it too. Anyone have info on it would be greatly appreciated.
I would like to add a little more info to the back-story of mods.
In the July 1992 edition of Audio Magazine, there was a brief of a mod kit from Soundaid (in NY, NY) for the M7. There was also a review in The Sensible Sound, Vol 10, No. 39. The kit was $29.95 and included two Solen 4.7 uF, 250-V capacitore, cabinet damping sheets of 1/8” thick sheets of material resembling Dynamat w/o any barrier material, a small bottle of Polyvinyl Acetate (PVA) and a small paintbrush to paint the woofer cone.
Instructions from Soundaid:
1. Remove the grill and remove screws holding in the woofer and tweeter.
2. Cut the stock gray cab and leave it on the board since it is hot-melt-glued, solder the new cap to the same stock wires.
3. Carefully coat the woofer cone, let dry for 24 hours and place a second coat.
4. Apply dampening sheets to top, bottom and sides but not the back or front.
5. Replace the fiberglass and woofer and tweeter, making sure all wires clear cabinet openings and then tighten all screws.
6. DO NOT attempt to treat the tweeter dome.
For those who fear coating the woofer will damage it, it did not since I did three pairs and they are fine. [As a side bar, another product to use when coating small paper cones is Grumbacher’s Damar Varnish. I learned about this product from reading about doping drivers and it works very effectively.] Someone mentioned using oil based modeling clay as a good cabinet dampening material. I hadn’t thought about using it but it should do fine and easy to roll out into flat 1/8” sheets. I also like to recommend Mortite’s Rope Caulk or Roof & Gutter instant patch tape would be good products to use. The Roof & Gutter tape is a PITA because it is tar based.
I’m interested in this thread because I still have two NOS pairs that I purchased in the early 90’s that should be modded. The epay one looks interesting but making the project more complicated. Also, I have a pair of Minimus 77’s and there was a mod for it too. Anyone have info on it would be greatly appreciated.
Pio1980
AK Member
Aside fro the smallest ADS/Braun, I do remember something called the Visonik David, little Euro precision mini-monitor overachievers that were supposed to be the very best of this breed and made quite a high-end-audio splash in the late-70's. Miller & Kreisel supposedly started the satellite+sub trend with these.
I don't know how many production changes or versions there were of the R-S mini-7s, I do know they are sought by users of communication type recievers for use as an external better quality speaker. I never cared enuff for the performance of any of the few I've had as anything to keep them for any use, are there good ones and not-so-good ones?
S.B.
I don't know how many production changes or versions there were of the R-S mini-7s, I do know they are sought by users of communication type recievers for use as an external better quality speaker. I never cared enuff for the performance of any of the few I've had as anything to keep them for any use, are there good ones and not-so-good ones?
S.B.
mhardy6647
Lunatic Member
So... after a quick perusal of this thread, I don't notice any mention of the fact that the earlier versions of these were sealed, and the later ones were ported. You might want to keep that in mind...
riverrat373
Active Member
Not all Minimus 7's are the same. I have a pair labeled OPTIMUS that are ported in the back. I have another pair that are labeled REALISTIC and are not ported. The ported one's have much better bass response. I bought the ported ones back in the early 90's when they were being closed out at a local Radio Shack for $40.00! The ones I have are cast aluminum bodies and I love them!