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It begins anew: I now have my very own M1.5t


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Just because I haven't been here doesn't mean I have not been finding new Carver bits. No, in fact I've been running hither and thither and snapping up Carver shinys like a certain madcap Italian plumber chases gold coins that inexplicably hover in mid-air. We won't speak of the mushrooms. 

 

As if the burgeoning stacks of audio components that threaten the structural integrity of the very floors of Schloss Butcher were not enough, I happened upon a quite equitable deal for an M1.5t recently. In a matter of hours, cash was placed in palm, amplifier placed in boot,  amplifier added to what has become a veritable pylon of recent acquisitions. 

 

Now for Q&A time. 

 

As I've been extraordinarily busy working on other projects, I have not yet had the spare moment to attempt configuring yet another system around yet another amplifier. I was not impressed with my M1.0t, but I was thrilled with my TFM-25. Even more so after a mate completed the capacitor upgrades. Where should I expect to find this amp in relation to the sound of the other two amps? Will this be the typical "here's a box of capacitors" upgrade or are there more things that need to be done? 

 

Here's the large question that looms o'er the land: Is this amplifier worth the space? Or should I parlay it into something more desirable?

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Proper speakers are the requisite answer. Something Polk, preferably. M-1.5t's can be bright. McIntosh speakers would be best, but hard to find without a second mortgage on said Schloss...

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34 minutes ago, kve777 said:

Proper speakers are the requisite answer. Something Polk, preferably. M-1.5t's can be bright. McIntosh speakers would be best, but hard to find without a second mortgage on said Schloss...

 

I happen to have just the right Polks here, provided this little sound sled is a common ground design.

I have never seen any decent McIntosh speakers in my area, more's the pity. 

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9 hours ago, DrummerJuice said:

I did find my M1.5t a bit bright. Do you have a tube preamp to tame it a bit? Have you considered Hashy's new MarkII mod? 

 

I know nothing about the mods for this amp, but I fear no mod as long as it doesn't involve welding or blacksmithing. I have no tubes, as I was soundly chastised here for even considering them. I do, however, have a very capable Hafler preamp that I've had completely reworked. It has a wonderful character and is somewhat effective at taming the flat, almost harsh character of my Hafler amps. 
 

I could also have a look-see for a C-1, and perform the correct mods on that one. Carver shiny has been a bit easier to find, of late. 

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15 hours ago, Butcher said:

 

I happen to have just the right Polks here, provided this little sound sled is a common ground design.

I have never seen any decent McIntosh speakers in my area, more's the pity. 

What is it about Polk speakers needing the amp to be common ground?  I had some Polk SDA-2's I ran with my m1.5t.  Sounded great.......briefly....  Then I lost one of the Polks.  Not sure if running them with the m1.5t wast the issue.  But folks have told me they are incompatible.  Why is that?  I've run the 1.5 with other speakers and had no issue.

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8 hours ago, Kurt said:

What is it about Polk speakers needing the amp to be common ground?  I had some Polk SDA-2's I ran with my m1.5t.  Sounded great.......briefly....  Then I lost one of the Polks.  Not sure if running them with the m1.5t wast the issue.  But folks have told me they are incompatible.  Why is that?  I've run the 1.5 with other speakers and had no issue.

 

Thats a particular divvy bit of prat that afflicts otherwise brilliant early models of the Stereo Dimensional Array speakers from Polk. An interconnect cable conjoins the two speakers carrying out of phase versions of each amplifier channel to the opposite channel's speaker. That signal is passed to one side of the SDA array, maths and physics happens, and each channel's crosstalk is nullified before it can reach the opposite ear. Quite nifty, actually. Bob Carver, the genius, did it with electronics so you can have a similar effect in most any good system without towers that are near two yards and thirteen stone.  A mate from my hifi shop did it with a pair of tiny speakers and some lengths of wire. 

 

Before the SDA was available, the top of the mountain at Polk Audio was the Monitor 12. After the SDA was released, the Monitor 12 was the new middle brother. A pair sat ignored in our shop. My pal decided to try his hand at duplicating the mind of Matthew Polk. He took a pair of Canton Plus S mini speakers - these brilliant little boxes that look similar to the famed Radio Shack Minimus 7 - placing one atop each Monitor 12. He took lengths of our cheapest speaker wire, connecting the terminals of each Canton to the terminals of the opposite Monitor 12, but he reversed the polarity when hooking them up. When all was done, we played quite a few of our test tracks and found this kludgy trick worked a charm. He proved the actual SDA effect was evident at half the cost per channel.

 

At this point I wonder what would have happened had he added the Hafler Circuit as well. Probably time travel.  And of course, perhaps we should have done all this with SST Trinaural speakers instead of the Monitor 12. That may have opened a doorway to a parallel dimension, I would imagine. 

 

But never mind that. You were asking why common ground was an issue with these speakers. The answer is that with the interconnect cable in place, one is essentially shorting each amp channel to the opposite channel's ground. With a common ground amplifier, each channel already shares the same return path, so introducing the right channel's electrical ground path to the left channel has no effect, because they're already hooked to the same ground. 

 

Does that make sense? I wonder. Saturday evenings are a bit akimbo for me some times. 

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1 hour ago, Butcher said:

 

Thats a particular divvy bit of prat that afflicts otherwise brilliant early models of the Stereo Dimensional Array speakers from Polk. An interconnect cable conjoins the two speakers carrying out of phase versions of each amplifier channel to the opposite channel's speaker. That signal is passed to one side of the SDA array, maths and physics happens, and each channel's crosstalk is nullified before it can reach the opposite ear. Quite nifty, actually. Bob Carver, the genius, did it with electronics so you can have a similar effect in most any good system without towers that are near two yards and thirteen stone.  A mate from my hifi shop did it with a pair of tiny speakers and some lengths of wire. 

 

Before the SDA was available, the top of the mountain at Polk Audio was the Monitor 12. After the SDA was released, the Monitor 12 was the new middle brother. A pair sat ignored in our shop. My pal decided to try his hand at duplicating the mind of Matthew Polk. He took a pair of Canton Plus S mini speakers - these brilliant little boxes that look similar to the famed Radio Shack Minimus 7 - placing one atop each Monitor 12. He took lengths of our cheapest speaker wire, connecting the terminals of each Canton to the terminals of the opposite Monitor 12, but he reversed the polarity when hooking them up. When all was done, we played quite a few of our test tracks and found this kludgy trick worked a charm. He proved the actual SDA effect was evident at half the cost per channel.

 

At this point I wonder what would have happened had he added the Hafler Circuit as well. Probably time travel.  And of course, perhaps we should have done all this with SST Trinaural speakers instead of the Monitor 12. That may have opened a doorway to a parallel dimension, I would imagine. 

 

But never mind that. You were asking why common ground was an issue with these speakers. The answer is that with the interconnect cable in place, one is essentially shorting each amp channel to the opposite channel's ground. With a common ground amplifier, each channel already shares the same return path, so introducing the right channel's electrical ground path to the left channel has no effect, because they're already hooked to the same ground. 

 

Does that make sense? I wonder. Saturday evenings are a bit akimbo for me some times. 

Thanks @Butcher Yes, That explanation helps.  I did not know that's how the Polk interconnect cable worked.  So, basically,  when combined (in Ghost Buster's parlance, when I "crossed the streams" :)), with the Carver it was bad news for one of my Polks.   Too bad, I kinda liked those speakers, even though they were massive and hard to move around.  I ended up selling the pair, "as was" to somebody who thought they could fix 'em.  Thanks again. 

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14 hours ago, Kurt said:

Thanks @Butcher Yes, That explanation helps.  I did not know that's how the Polk interconnect cable worked.  So, basically,  when combined (in Ghost Buster's parlance, when I "crossed the streams" :)), with the Carver it was bad news for one of my Polks.   Too bad, I kinda liked those speakers, even though they were massive and hard to move around.  I ended up selling the pair, "as was" to somebody who thought they could fix 'em.  Thanks again. 

 

Its a shame you gave them up. They are indeed difficult to move around. Mine are a bit over seven stone heavier than your SDA 2 were. If I need to move them, I must be quite serious about it. 

 

6 hours ago, RodH said:

I believe the M1.5t is a common ground unit - not inverting.

 

In that case, what befell Kurt may have related to an issue with his amp, a defect in his SDA 2, or perhaps both?

 

I believe an easy way to confirm common ground is to simply set a multimeter to read ohms and then place the leads in the negative terminals of a given amplifier. Continuity shows common ground, infinite resistance shows inverting. 

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A look at the backside of an M1.5t reveals the earth (ground) symbol adorning both negative posts.

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