Mauro Penasa MyRef vs simple LM3886 circuit - Page 6 - diyAudio
Go Back   Home > Forums > Amplifiers > Chip Amps

Chip Amps Amplifiers based on integrated circuits

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 21st May 2012, 12:59 PM   #51
soongsc is offline soongsc  Taiwan
diyAudio Member
 
soongsc's Avatar
 
Join Date: Mar 2005
Location: Taiwan
Quote:
Originally Posted by AndrewT View Post
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.
Having a higher sensitivity does not mean it has lots of headroom. Normally you also have to look at the BL curve. But you may be correct. There are drivers out there that max out at very low voltages even though they are large and sensitive drivers. In this case it makes no sense to have higher driving voltage or wattage amplifier. But the drivers I look at generally have increased maximum driving voltage capability with size. For drivers of the same size, higher sensitivity generally do have lower Xmax, in this case you need less driving voltage for it to reach max excursion. So I think we are looking at the issue from different points of views. I tend to look for drivers of similar sensitivity and a wider range of excursion. Maybe the Fostex drivers mentioned have higher sensitivity than I am used to. Selection of drivers is a more complicated process, not only simple sensitivity numbers. The maximum sound pressure level you wish for the target bandwidth is just as important. If you have an amplifier that is clipping before the driver maximum capability is reached, you are wasting the driver; if you have the driver maxing out before the amplifier limit is reached, you are wasting power capability.

Good luck with whatever you like to choose.
__________________
Hear the real thing!

Last edited by soongsc; 21st May 2012 at 01:04 PM.
  Reply With Quote
Old 21st May 2012, 01:36 PM   #52
diyAudio Member
 
Join Date: Jan 2011
i think 60w is enough to drive 8" to 12" woofers with sensitivity >=90dB (the woofers i have in my mind are all having more than 90dB sensitivity and are rated at 8 ohms). if not LM3886's in bridge mode can be used. the real question is 'is it worth to spend more on driving woofers using MyRef amps? as these woofers will only cover upto 250hz (max). or even less. in my case if FE126En(in bk-12m back loaded horn) are capable of reaching below 150hz, then i will cross the woofers at 150hz only. so considering the small freq.range that woofers will be operating on, will it make sense to use just normal LM3886 amps for woofers and MyRef amps for fullrangers?
(i am speaking this with the knowledge that significant music information lies between 300hz to 3000hz)
  Reply With Quote
Old 21st May 2012, 01:46 PM   #53
bcmbob is offline bcmbob  United States
diyAudio Member
 
Join Date: Dec 2009
Location: Bay City, Michigan
soundnovice, are you thinking living room levels or "Party" SPL? - or both?
__________________
Bob M.
"Arrange Whatever Pieces Come Your Way."
  Reply With Quote
Old 21st May 2012, 02:07 PM   #54
diyAudio Member
 
Join Date: Jan 2011
Quote:
Originally Posted by bcmbob View Post
soundnovice, are you thinking living room levels or "Party" SPL? - or both?
just living room levels
  Reply With Quote
Old 21st May 2012, 02:17 PM   #55
soongsc is offline soongsc  Taiwan
diyAudio Member
 
soongsc's Avatar
 
Join Date: Mar 2005
Location: Taiwan
Here is some damping characteristic measurement comparison. Green is a MyRef, Red is a 120W commercial amplifier. Both measurements had the same driver as a load.
Click the image to open in full size.
Wattage is not everything. The MyRef has better bass than the 120W amp, and sounds MUCH better.
__________________
Hear the real thing!
  Reply With Quote
Old 21st May 2012, 02:38 PM   #56
bcmbob is offline bcmbob  United States
diyAudio Member
 
Join Date: Dec 2009
Location: Bay City, Michigan
To give you an idea of what a MyRef can easily handle, these are the speakers I'm using.

https://sites.google.com/site/undefi...diy-sunflowers

There is some good driver information on the page and at the corresponding links at Parts Express. My listening room is ~ 12X17 and just the MyRefs give all the full spectrum SPL for 90% of the music I play. I did asked Paul the designer, if he considered a 10 or 12 inch version. He said from what he hears and the response he gets from builder - there is no need for that at normal listening levels, though it would be fun. (BTW, he is just starting a new full range driver cabinet design)

I am in no way trying to discourage anyone from the adventure of bi-amping. Just want to offer some insight on some sort of baseline.
__________________
Bob M.
"Arrange Whatever Pieces Come Your Way."

Last edited by bcmbob; 21st May 2012 at 02:45 PM.
  Reply With Quote
Old 21st May 2012, 06:28 PM   #57
diyAudio Member
 
Join Date: Jan 2011
after reading articles about bi-amping on ESP and about active xovers on Linkwitz pages, i am more inclined towards biamping the speakers. infact miniDSP will solve eq related issues such as i read about vocal shout in the fe126en drivers.
  Reply With Quote
Old 31st May 2012, 09:15 PM   #58
bcmbob is offline bcmbob  United States
diyAudio Member
 
Join Date: Dec 2009
Location: Bay City, Michigan
Quote:
Originally Posted by Dufus View Post
Bob how about that review you promised? Did you compared it to some boutique amps?
More difficult to get than I had thought. Look here:My_Ref Fremen Edition - Beta build/Fine tuning
__________________
Bob M.
"Arrange Whatever Pieces Come Your Way."
  Reply With Quote
Old 5th June 2012, 11:19 AM   #59
diyAudio Member
 
Join Date: Jan 2011
i am changing the participant of the competition now!
how about some opinions on 'MyRef Vs T-amp'?
  Reply With Quote
Old 5th June 2012, 11:37 AM   #60
soongsc is offline soongsc  Taiwan
diyAudio Member
 
soongsc's Avatar
 
Join Date: Mar 2005
Location: Taiwan
Never got my T amp working. Might give it a try again some time in the future. The T amps I have listened to in different systems never seemed attractive to me. But I think maybe someone with more hands on experience can open a new thread for that comparison.
__________________
Hear the real thing!
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Mauro Penasa MyRef RevC GainClone Mono Blocks apoopoo999 Swap Meet 6 29th July 2011 04:27 AM
my_ref revC group buy (Mauro Penasa LM3886 design) schro20 Group Buys 650 17th October 2010 11:42 PM
Evolution Amplifier by Mauro Penasa Panelhead Chip Amps 14 22nd July 2010 09:56 AM
WTB: Mauro Penasa Ref C marginwalker Swap Meet 0 13th October 2007 05:28 PM
MY_REF EVOLUTION by MAURO PENASA goldkenn Chip Amps 8 25th September 2007 04:50 PM


New To Site? Need Help?

All times are GMT. The time now is 02:21 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2