Question For The Home Stereo DIY Guru's

[Stike]

So I've got a couple Marshall mini stacks that while adorable just don't sound all that hot. I was wondering how feasable it would be to convert the 1X10" cabinets into stereo speakers?

[JohnnyB]

So I've got a couple Marshall mini stacks that while adorable just don't sound all that hot. I was wondering how feasable it would be to convert the 1X10" cabinets into stereo speakers?

You could take speaker wire and terminate it at the Marshall end with 1/4" phone plugs. Make sure you solder the positive leads to the positive terminals in the plugs. When you hook it up, sound will come out, but will not give you much bass or treble extension, or frequency linearity in the audible parts either, for that matter. There's a reason stereo speakers have crossovers and tweeters. Also, even though the Marshall mini drivers are 10" dis., they won't give you much bass because the cabinets are small.

Seriously, you'd get better sound from these, on sale at $29.95/pair, especially if you mount them on real speaker stands.

And if you want to splurge, go for these Pioneers on sale via Amazon at a whopping $90/pair.

They also deserve stands. At Amazon there are 46 user ratings at an average of 4.72 stars for these Pioneers. The lowest rating is 3 stars, mostly for not having a fancy exterior. They've also garnered rave reviews from the audiophile mags.

[Stike]

I hadn't intended on using the OEM 10"s but was curious as to how tricky it would be to more or less shoehorn halfway decent stereo speakers in the Marshall cabinets. This is for the stereo at the shop so this project is as much about "the look" as it is the sound.

[JohnnyB]

I hadn't intended on using the OEM 10"s but was curious as to how tricky it would be to more or less shoehorn halfway decent stereo speakers in the Marshall cabinets. This is for the stereo at the shop so this project is as much about "the look" as it is the sound.

Oh. In that case, what you'd need is to decide on a kit of speaker components, wiring, and crossovers, and make a replacement baffle for the Marshalls to mount the drivers on. You'd want to measure the interior volume of the Marshall cabs and then buy a kit that comes the closest to working with a cabinet of that volume. If the Marshalls are sealed, you will probably have to drill a 2" or 3" dia. hole in the back and mount a port tube of the length that best matches the woofer's loading and the cabinet volume. For example, if the interior dimensions of a mini cab were 15"x15"x10", that comes to 1.3 cu. ft., and you would shop for a woofer optimized to work in that size cabinet, and match it with a tweeter.

It would be easier (and probably cheaper) to remove the baffles from the Marshalls, but keep the grill cloths in place, and hide either the Dayton or Pioneer speakers inside the Marshall cabs. Maybe this is what you had in mind in the first place.

If that's the case, you need to get the interior dimensions of the cabinets and find speakers that will fit inside. I think the Daytons or Pioneers previously mentioned would fit. You'd remove the front baffle, but probably need to put in some sort of metal mesh to keep the grill cloth in place. Then modify the back panel as needed to get the wiring into the speaker cabs inside. You'd probably want to stuff some acrylic batting or foam between the stereo speakers and the walls of the Marshall cabs to dampen vibration and potential resonances.

[Stike]

The Dayton's will fit. Thanks for the link!

[JohnnyB]

The Dayton's will fit. Thanks for the link!

Great! Stereophile actually reviewed them and liked them! At the sale price there's no way you could DIY for anywhere near that. If I had some money to play with, I'd stack 6-10 pairs to make line arrays. Even ten pairs come to the price of one entry-level pair of small speakers from PSB, Paradigm, Energy, Polk, etc.

These Daytons on sale are the price of a couple of music albums. Ridiculous!

[Toadroller]

The Dayton's will fit. Thanks for the link!

Great! Stereophile actually reviewed them and liked them! At the sale price there's no way you could DIY for anywhere near that. If I had some money to play with, I'd stack 6-10 pairs to make line arrays. Even ten pairs come to the price of one entry-level pair of small speakers from PSB, Paradigm, Energy, Polk, etc.

That's an interesting concept and an even stranger visual. How would you wire 6 stacked speakers, in parallel?

[JohnnyB]

The Dayton's will fit. Thanks for the link!

Great! Stereophile actually reviewed them and liked them! At the sale price there's no way you could DIY for anywhere near that. If I had some money to play with, I'd stack 6-10 pairs to make line arrays. Even ten pairs come to the price of one entry-level pair of small speakers from PSB, Paradigm, Energy, Polk, etc.

That's an interesting concept and an even stranger visual. How would you wire 6 stacked speakers, in parallel?

A real line array can be a strange visual:

I'm talking about positioning 8-10 of the little Daytons sideways, stacking them on a 12" high platform or speaker stand, probably with the tweeters to the outside as shown above. As for the wiring, it would require some combination of series and parallel connections to keep the nominal impedance somewhere between 4 and 12 ohms. If wired completely in parallel, a stack of eight 8-ohm speakers would have an impedance around 1/16 of an ohm, and there aren't too many amps that could handle that.

Line arrays offer special advantages: 1) The effect of driver interaction limits vertical dispersion, lowering or eliminating sound bouncing from the floor and ceiling; this eliminates much of the resonance and time smear you get from room interactions, 2) The great number of drivers provides enormous clean dynamic range. The drivers don't have to work so hard to get loud, 3) Line arrays launch a bigger, stronger wave. Conventional speakers lose 6 dB for every doubling of distance; line arrays lose only half that. So for example, if a point source measures 90 dB at 1 meter, it'll measure 84 dB at 2 meters but a line array will make 87 dB at 2 meters.

[tomteriffic]

For 6 of the Daytons on a side, wire two sets of three speakers each in parallel, then run each of the sets (of three) in series. This should equate to an impedance of 5.33 ohms.

To run 8 on a side, wire four sets of two speakers each, with each pair of speakers being wired in series. Then take the four pairs and wire them in parallel. This should yield a total impedance of 4 ohms.

10 gets messy.

[Armitage]

I'd think the time alignment of all those tweeters would be a mess.

[Toadroller]

While you're at it, might want to make a pair (or maybe half the set?) point backward and have yourself an ersatz bipolar array, eh Or double your fun for the same purpose: a back to back stack of six each side.

Would the stronger wave front bring the bass into better tonal balance?

[JohnnyB]

I'd think the time alignment of all those tweeters would be a mess.

Because of this, most line array speakers are meant to be listened to at 9 feet away or more, and definitely not for nearfield. There are a few designs that stair-step the drivers slightly, but most makers mount them on a flat baffle. There are also a few that curve the array outward like the ones pictured earlier.

While you're at it, might want to make a pair (or maybe half the set?) point backward and have yourself an ersatz bipolar array, eh Or double your fun for the same purpose: a back to back stack of six each side.

I've thought about this quite a bit as well. When Mirage Loudspeakers designed their omnidirectional speakers after making bipolars for 20 years, they tilted the omnidirectional assembly forward to get a 60/40 mix of front-to-back radiation. This was based on years of research into the radiating patterns of singers and musical instruments. So, for example, with ten speakers per side one might have 6 in a forward-facing line array and either a stack of four facing rearward or two pairs forming a triangle with the 6-speaker line array in the front. With 9 you could make an equilateral triangle or an array of 6 to the front and three to the back. With a properly designed wire harness you could experiment endlessly.

Would the stronger wave front bring the bass into better tonal balance?

That's evidently not a big factor given the length of bass sound waves. There are speaker designs with the woofers on the front, sides, bottom, and back with no detrimental effect that I've heard of. I have a pair of floorstanding bipolars, with equal front- and rear-mounted woofers and ports, and the bass on these speakers is phenomenal, both in lifelike speed and clarity, and also in strength and extension. You get a problem with dipole speakers where the backwave of the woofer is out of phase with the front, and therefore cancels some of the bass energy.

Bass wavelengths are so long the difference of woofer position on the speaker array isn't so critical. A 100 Hz wavelength is over 11 feet long; even 150 Hz wavelength is 7.5 feet long, and a 37 Hz is around 30 feet. This does not mean, however, that--despite what some manufacturers say--you can put a sub woofer anywhere in the room and it'll be OK.

Controlling the treble may be a factor, however. Most speakers are designed for the high treble to roll off sharply off-axis. If the tweeter is omnidirectional without some attenuation, it could sound too bright as more of the room is reflecting these high frequencies. See the measurements of this omnidirectional speaker as well as the manufacturer's comments in response. The testers measured frequency response in an anechoic environment which showed a several treble rolloff, but the speaker was designed to be listened to in a typical listening room where the room reflections are called into play.

[Stike]

Okay, got the Daytons in today(ordered 2 pair)-very nice bang for the buck and they fit inside the Marshall cabs beautifully. One last question though. Since I have 2 stacks (one will be left the other right) I'll need to wire 2 of the Daytons to act as one-what's the best way to do that?

[JohnnyB]

Okay, got the Daytons in today(ordered 2 pair)-very nice bang for the buck and they fit inside the Marshall cabs beautifully. One last question though. Since I have 2 stacks (one will be left the other right) I'll need to wire 2 of the Daytons to act as one-what's the best way to do that?

What sort of amp or receiver are you using to power them? Is it a receiver that has two pairs of speaker outputs? In that case you could run separate speaker cables to each of the two pairs of speakers provided the amp documentation says it's safe to hook up two pairs of 8-ohm speakers this way.

Here's a diagram of wiring speakers in series. The Dayton speakers are rated at 8 ohms, so wiring this way would present a 16-ohm load to your amplifier.

Here's a diagram of wiring speakers in parallel, which would present a 4-ohm load to your amplifier:

[Stike]

What sort of amp or receiver are you using to power them? Is it a receiver that has two pairs of speaker outputs? In that case you could run separate speaker cables to each of the two pairs of speakers provided the amp documentation says it's safe to hook up two pairs of 8-ohm speakers this way.

Thanks for the diagrams. The receiver does have two pairs of speaker outputs but I have a pair of old Boston Acoustic A60's that I'm going to have on the opposite wall, big room.

[JohnnyB]

What sort of amp or receiver are you using to power them? Is it a receiver that has two pairs of speaker outputs? In that case you could run separate speaker cables to each of the two pairs of speakers provided the amp documentation says it's safe to hook up two pairs of 8-ohm speakers this way.

Thanks for the diagrams. The receiver does have two pairs of speaker outputs but I have a pair of old Boston Acoustic A60's that I'm going to have on the opposite wall, big room.

In that case wire the two pairs of Daytons in series. When you play those plus the A60s on the other set of speaker outputs, the receiver will see an overall nominal load of around 5.33 ohms. If you wired the Daytons in parallel and ran the Bostons at the same time, the total load would be 2.67 ohms, not a good thing.

[Toadroller]

Good old BA 60s.

My dad went into Tweeter, etc. around 1980 to upgrade his old Heathkit-Wharfdale set from the late 60s and made the mistake of taking me and my older brother along.

After much debate he came out with a Yamaha receiver (R-440 if memory serves correctly), a Yamaha tape deck, and a pair of Boston A-100s. Pretty nifty full range 8" acoustic suspension drivers. I'm sure they're still holding up the end of a busted piano or tractor out in his barn somewhere. The neighborhood teenagers came round with their albums to tape them. As recently as this evening I was cranking Utopia's "Adventures in Utopia," which was one of the albums the neighbor kid introduced us to. Other albums included Cheap Trick's Dream Police and Boston's first.

This, plus the encouragement of slightly older cousins, got us into stereos in our teens. If only I'd realized then that being artistic made more of an impression with the ladies than a loud stereo...

Good stuff!

[JohnnyB]

Tweeter, etc.? Are you in New England somewhere? I lived in the Boston area for a year (1987-8) and I remember the two decent audio chains were Tweeter, etc. and Nantucket Sound. I had just bought some ADS speakers in California before moving there and auditioned ADS's new line at one of those stores when I got to greater Boston. Did you know that Andy Petit, founder of Boston Acoustics, had previously been a major wheel at ADS? ADS is long gone but BA lives on as part of DM Holdings, which includes Denon, McIntosh, and Marantz--good company to be in.

[Toadroller]

I spent my youth in southern New Hampshire from the decade of approximately 78 - 91 before a 14 year sojourn to Colorado (oh, how we miss the front range. For that matter, we Honeymooned in Seattle and Vancouver in '94. Returning to either on business is always a treat for me. Last time there I stopped it at, I want to say, Emerald City Guitars. Plucking a G&L, I struck up conversation with a fellow patron who turned out to be from New Hampshire himself. Go figure. Conversation elsewhere in the shop turned to recent visits from Gary Kramer... but I digress) before returning to New England to rediscover the 52 seasons Maine has to offer. Each week is unique and repeated, year for year. Here we reside. Escape is futile, though not necessarily sought, despite the tax haven of my youth being a two hour drive away. Not just yet. Today's blizzard is not a factor. A foot of snow is fun. I've got a snow blower. Good fun.

Back to the 80s.

Tweeter, some of which became Cookin', was the de-facto chain. Here I heard BA, Snell (also owned by the DM holdings group if the transitive property of BA ownership applies (gosh, it's like Fender to Hamer, isn't it?) and of which I've approached my zenith, the Snell B-minors, with which I am fully satisfied), Denon, Adcom, Dahlquist, Bang and Olufsen, and the tape deck of the 80s, Nakamichi. My brother bough the BX-100; we had dreams of Dragons. A trip to Boston would get you into higher realms of the audio world through places like (and memory is failing me here- Brooklyne Audio?), where you could hear Rotel, Spectral, Meitner, etc. But I ramble. Left out of my earlier post was the fact that my father came away with ADS speakers which, after a few weeks, he upgraded to the BA 100s. BAs offered bass; in today's informed world, I'm sure the ADS were a better speaker, but so be it.

Tweeter got a fair amount of my 18-20 year old cash, including a (gorgeous, unique, but useless) B&O tape deck which I recently gave to a local stereo fix-it shop to repair a pair of classic CD players, a Rotel 850 and my $650 investment at age twenty, a Denon DCD 2560. A tank, to be sure, but they actually reviewed it in Stereophile so, you know, it must have been awesome. Corey Greenberg, Tom Norton, what-all; I was 19.

I chased audio apogees for years until children came along and guitars became my main focus. Playing with purposeful distortion of guitar amplifiers has taught me a lot about non-distorted musical reproduction. A home renovation put the stereo in the corner, expensive cable on the 'what am I thinking?' platform, and, through your advise elsewhere, a Panasonic Viera plasma on the wall. The B-minors have been pulled out of retirement, but they're hooked up to a Marantz receiver (not bad) but not the Aragon pre to vertically bi-amped Aragon 4004 (for the woofs) and Musical Concepts modified Hafler DH-200 (seriously, as sweet as solid state gets) (for the upper range) as I used to change. The Hafler is unplugged and the Aragon powers, begrudgingly, subwoofers. Shame, shame.

Yep, I'm from New England, like ThunderNotes, who knows the back-streets of ManchVegas* better than I do.

*Manchester, NH, home to Adam Sandler, who my younger sister has bumped into on occasion in pool halls with his old Manch-West (or did he go to Central?) high school buddies.

[JohnnyB]

Snell B Minors. I'm impressed! We probably have some similar tastes in sound reproduction and tonal balance. Kevin Voecks was chief of engineering at Snell from about 1985-95 and introduced, among other models, the B Minors. Astute design there, with MTM D'Appolito array, side-firing 12" woofer, and rear-firing tweeter.

Voecks did a lot of the designing for Mirage as well, and I currently have 14 Mirage speakers in my house, of which 13 are active. Now Voecks is tearing it up at Revel Loudspeakers.

I consider DM Holdings one of the good guys, as they've bought up and increased viability for some very good audio companies--Marantz, McIntosh, Denon, Boston Acoustics, and some others. DM picked BA up around 2006, and that's when there were all those great closeouts out there. I picked up their $2K surround processor for about $650 and several HFC-ers got their $1500 home theater speaker pack for around $200 back then. I had ADS L1090 speakers for 9 years and as I said, that's where the founder/chief designer of BA came from.

For three years I worked in downtown Seattle about 4 blocks from Emerald City Guitars, which resulted in several very expensive lunch breaks including returning to work with my first Hamer, a like-new Eclipse-12 in vintage orange. When Scottcrud was out here in Aug. 2011 we went there to check things out.

Did you get any use out of the pitch control on the Denon DCD 2560?

[Stike]

New shop stereo installed. Those Daytons sound just fine, thanks for the hot tip!

[JohnnyB]

Congratulations. Your vision was realized and it was a great one, especially for the setting.

[JohnnyB]

New shop stereo installed. Those Daytons sound just fine, thanks for the hot tip!

Next project for a Marshall Mini Stack: A mini-fridge like Martin Taylor's.

[LostArt]

cross over

tweets

and a terminal strip

done

[singlehum]

Johnny B...any thoughts on the Dayton subwoofers that are linked o on the Parts Express site?

[JohnnyB]

Johnny B...any thoughts on the Dayton subwoofers that are linked o on the Parts Express site?

Normally I can't stand cheap subs, but I trust this reviewer, and his evaluation is very encouraging. Although he didn't have those Dayton bookshelf speakers on hand, he did audition the sub with the same Pioneer speakers I mentioned at the beginning of this thread. He swapped the Pioneers in for the Sonys because the sub was clearly better than the Sony speakers. Also, notice how positive the customer reviews are for the Dayton powered subs. They average 4-1/2 stars with dozens of reviewers for each model.