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Please forgive me... I have sinned and broken all the rules. I know not what I'm doing.

I purchased several weeks back a pair of Dayton 12" subs for the ridiculous price of $160 for BOTH after reading Jmans excellent review. They sound very good and I'm very pleased with them as they are. However...

From my last listening room I had a pair of NHT 1259 in sealed 3.2 cu.ft enclosure. They were too large for my new space so they were just sitting in the garage.

Curiosity got the best of me. The NHT speaker is identical in size to the Dayton. Even the screw holes match. They're 4 ohms also the same as the Dayton. What if I just switched drivers??? If I don't like it I can just switch it back. A few screws...easy enough.

The NHT driver is the same size but it is much heavier. Could the 120 watt RMS amp drive this speaker? I have NO idea. Another possible problem is the NHT is designed for a SEALED 3 cu. ft enclosure. The Dayton cabinet is around 2.5 cu.ft. and is ported which can be easily plugged but still very undersized even with added stuffing.

Out popped the Dayton driver, put in some poly-fill, plugged the port and put the clips back on the NHT and she fit like a glove. So far so good.

I did only one sub as a test instead of going to the trouble of doing both and have a double fail.

Turned on some bass heavy music and... it was working but sound was rather soft and laid back. Not impressed. The ported Dayton was better. Before ditching the project I decided just for fun to see what would happen if the port plug was removed. This was like letting Genie out of the bottle!!!!!!!!!

Wait a minute... this isn't supposed to happen! A sealed driver in an undersized cabinet with only 120 watt rms. This is SOOO wrong but it feels sooo right.:rubeyes:

I could just imagine what two of them would sound like! I was now excited to 'go all the way'. I did the switch with the other driver and now had two of these ready to test.

When I turned on some bass heavy music I was BLOWN AWAY!!! (Literally went tumbling across the room) I couldn't believe what I was hearing. I had to turn it down. I had plenty of power. I could play this loud enough to where the neighbors would complain a block away. Two of these together in my small 15' x 15' x 10' room were vibrating the concrete walls. Pounding bass and I'm thrilled beyond belief. It also plays well at lower volume. It also plays nice with Jazz or classical. Properly adjusted, I can hear the texture of the base strings with an authoritative underlying strength. Nice and tight and no muddiness.

I spent the last day in disbelief. It was not good as a sealed unit but rather ported did the magic. Night and day. The Dayton speakers were good and set up as duals it gave an enjoyable experience but the NHT drivers are far superior. The base foundation is much more substantial. More weight to it. I have to say it was... awesome!

This is nothing but pure luck. The driver just happened to fit in the cabinet.

A couple of points...One observation is that the NHT driver face is 1/2" larger diameter due to a smaller rubber surround.

The other point is how well the little 120 watt (toroidal) amp did the job so admirably. Never once faltered. Plenty of power. My big question is why would I need a bigger amp? (Volume knob never went past half way.) If, for example, I'm only using say 75 watts total what good is another 200 or 300 watts on top of that? Would it sound any better? Watts are watts.. right? Does additional headroom add any benefit to the sound? Having this experience was eye opening in this regard.
 

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The NHT driver is the same size but it is much heavier. Could the 120 watt RMS amp drive this speaker? I have NO idea. Another possible problem is the NHT is designed for a SEALED 3 cu. ft enclosure. The Dayton cabinet is around 2.5 cu.ft. and is ported which can be easily plugged but still very undersized even with added stuffing.

Wait a minute... this isn't supposed to happen! A sealed driver in an undersized cabinet with only 120 watt rms. This is SOOO wrong but it feels sooo right.:rubeyes:
Glad your experiment worked so well. That's rarely the case when someone swaps drivers like that, but it isn't unheard of...

Drivers are engineered for a specific alignment, amplifier power and cabinet volume, but it's not without precedence to find something that works outside those specifications. It's all about something called T/S parameters (Thiele/Small), a set of both mechanical and electrical properties for the driver. A manufacturer custom tailors them for their specific design, but that doesn't necessarily exclude it from functioning in a different alignment. Moving the NHT drivers from a large sealed cabinet to a mid-sized ported one means they won't really operate to their fullest potential, but as you found they can be made to work quite well.

I would caution you to be judicious with the volume knob though. Drivers designed for a sealed enclosure are expecting additional suspension reinforcement from the air trapped inside the cabinet. By using a ported alignment you've eliminated that almost entirely, meaning the driver could easily over-extend itself if you listen to something with an aggressive soundtrack at an elevated volume.


This is nothing but pure luck.
You have no idea. ;)


The other point is how well the little 120 watt (toroidal) amp did the job so admirably. Never once faltered. Plenty of power. My big question is why would I need a bigger amp? (Volume knob never went past half way.) If, for example, I'm only using say 75 watts total what good is another 200 or 300 watts on top of that? Would it sound any better? Watts are watts.. right? Does additional headroom add any benefit to the sound? Having this experience was eye opening in this regard.
The gain control position has no bearing on the actual watts being used, so don't correlate the two of them. Think of that as more of a 'volume' knob then anything else. Audio is dynamic in nature and as such the power required to reproduce something will also vary, frequently by a wide margin. Additional capacity (headroom) is necessary to effectively produce those transient swings without stressing any component to the point of distortion. Having something in reserve is certainly not a bad problem to have because you will definitely tap into it with the soundtracks from the movies being made today.
 
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