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Old 21st May 2012, 08:48 AM   #41
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Quote:
Originally Posted by soongsc View Post
I would use the same amp for all bands unless the woofer is something like 12" or more.
does this mean that MyRef will not properly drive woofer of 12" or more size?
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Old 21st May 2012, 08:51 AM   #42
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Quote:
Originally Posted by soundnovice View Post
does this mean that MyRef will not properly drive woofer of 12" or more size?
It's more a question of sensitivity and desired SPL.

The My_Ref is a 46W amp.
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Old 21st May 2012, 09:41 AM   #43
bcmbob is offline bcmbob  United States
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Hey soundnovice,

When I was at stock builds of V1.2 and V 1.3 I started a project with some BPA-150s for the bottom of a bi-amped system. I still think it's a productive approach if one is using 4 ohm woofers, but I found the actual SPL to be about the same as the MyRef. One of the veteran MR builders, Tom E, has been perfecting a bi-amp - active crossover system for several months. You might get some good info with a PM and a search of his posts.

It should be noted that the addition of the Mundorf AG caps at C3 and C8, plus a larger transformer has given me all the deep, controlled and musical bottom end I can handle. With that combination the MyRefs do everything from shaking the house with pipe organ pedal notes to finely played bass lines in a jazz trio. The beauty of the MyRef approach, it's best feature is just letting what's being fed come through over the entire spectrum.
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Old 21st May 2012, 09:53 AM   #44
soongsc is offline soongsc  Taiwan
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Quote:
Originally Posted by soundnovice View Post
does this mean that MyRef will not properly drive woofer of 12" or more size?
It depends on how much voltage it will take to drive the woofer to max travel. You don't want the amp to max out before the driver. If you have an abundance of low frequency in music content, the summation can get pretty high.
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Old 21st May 2012, 12:04 PM   #45
AndrewT is offline AndrewT  Scotland
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The required drive voltage to the speaker is determined by the SPL and the speaker sensitivity.
Bigger speakers tend to have higher sensitivity (more SPL for the same drive voltage).

A driver that is big relative to the other drivers in the speaker is likely to require less drive voltage than the other drivers, not more !!!!!!

By way of example:
a normal 8ohm 2way speaker with 6.5" & 1" drive units that are both 88dB/W @ 1m when assembled into a passive cross-overed speaker may result in a speaker that is 87dB/W @ 1m.

If you replace the 6.5" driver with a 12" driver with a sensitivity of 88dB/W @ 1m then the drive voltage requirement has not changed and with a bit of correction to the passive crossover will reproduce the same SPL as the unmodified speaker.

However, if you chose a higher sensitivity 12" (or bigger) driver, maybe 92dB/W @ 1m then the new speaker will have a bass/mid response that is around 4dB higher than the treble. The speaker will sound as though it had very much reduced treble output.

The way to solve this is to send a lower drive voltage to the high sensitivity Bass/Mid driver.

Soongsc, this is the complete opposite to what your post implied.
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Last edited by AndrewT; 21st May 2012 at 12:11 PM.
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Old 21st May 2012, 12:11 PM   #46
AndrewT is offline AndrewT  Scotland
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Quote:
Originally Posted by soongsc View Post
It depends on how much voltage it will take to drive the woofer to max travel. You don't want the amp to max out before the driver. If you have an abundance of low frequency in music content, the summation can get pretty high.
this is complete nonsense. !!!!
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Old 21st May 2012, 12:13 PM   #47
AndrewT is offline AndrewT  Scotland
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Quote:
Originally Posted by bcmbob View Post
........... the addition of the Mundorf AG caps at C3 and C8, plus a larger transformer has given me all the deep, controlled and musical bottom end I can handle. With that combination the MyRefs do everything from shaking the house with pipe organ pedal notes to finely played bass lines in a jazz trio. The beauty of the MyRef approach, it's best feature is just letting what's being fed come through over the entire spectrum.
are these C3 & C8 the same as in the FE thread?
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Old 21st May 2012, 12:21 PM   #48
bcmbob is offline bcmbob  United States
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Yes Andrew, they are great for V1.2 through the FE. A bit expensive ~$30 each, but worth every penny.
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Old 21st May 2012, 12:24 PM   #49
AndrewT is offline AndrewT  Scotland
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expensive ~$30 each, but worth every penny.
has that just added 12700pennies to the cost of a 2ch amplifier?
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Old 21st May 2012, 12:34 PM   #50
bcmbob is offline bcmbob  United States
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Not bad speed for quick head calcs, Those big numbers help keep the world economy running.

I guess all things are relative - Check out the middle of this page Teflon Film and Tin Foil audio capacitors by V-Cap

BTW, I got mine from Parts Conexxion in Canada.
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Last edited by bcmbob; 21st May 2012 at 12:49 PM.
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