And Now For Something REALLY BIG - Page 76 - diyAudio
Go Back   Home > Forums > Loudspeakers > Multi-Way

Multi-Way Conventional loudspeakers with crossovers

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 11th January 2013, 03:49 AM   #751
Pano is offline Pano  United States
diyAudio Moderator
 
Pano's Avatar
 
Join Date: Oct 2004
Location: Kona, Hawaii
Blog Entries: 4
You could do it digitally, but why? If you are running an active system you need level adjustments at the amp. And unless you have a very clean, very quiet amp for the horns, you really should be attenuating there, too. Use the digital volume for fine tuning, not gross adjustments. It's all about gain and noise. You can read my article on Gain Structure/Gain Staging right here on diyAudio.com
__________________
Big Altec Moving Sale!
  Reply With Quote
Old 11th January 2013, 04:11 AM   #752
diyAudio Member
 
JRKO's Avatar
 
Join Date: Dec 2003
Location: U.K.
Send a message via AIM to JRKO
ok. I was thinking of keeping the 'dsp volume open fully (maybe change to manage gain - nice article btw) and using the preamp volume to be the main system control.

I could then have normal volume controls built into the high & low freq amps. Would L&R Lpads be of more use?
__________________
If I'm not making noise, I'm making something to make noise
  Reply With Quote
Old 11th January 2013, 04:31 AM   #753
Pano is offline Pano  United States
diyAudio Moderator
 
Pano's Avatar
 
Join Date: Oct 2004
Location: Kona, Hawaii
Blog Entries: 4
A volume control on the amp inputs is almost a must. You'd have to do some clever planning to avoid it.

I certainly recommend the L-Pad. Unless your horn amp is very low power and very quiet, you'll need it. Horns are very efficient. That means all the hiss, hum, buzz, rizz, etc. that you don't notice on normal speakers will be plenty obvious on the horns. Dropping the horn's level 6-12dB will get the amp's output up out of the dirt. Yes, you'll need more power, but that's rarely a problem in domestic settings.
__________________
Big Altec Moving Sale!
  Reply With Quote
Old 11th January 2013, 06:18 AM   #754
diyAudio Member
 
JRKO's Avatar
 
Join Date: Dec 2003
Location: U.K.
Send a message via AIM to JRKO
Will a stereo lpad like Stereo L - Pad LPAD Speaker Volume Control 8 Ohm 400 W | eBay this be ok or are seperate versions better?

Also on the bass amp is an lpad required as most of the attenuation will be bringing the high amp down?

lpads differ from standard pots as far a I can see because "L-pads adjust the relative volume of driver(s)/speaker(s) connected to them by placing added resistance in series. At the same time, a counter-resistance is placed in parallel with the driver(s)/speaker(s) to maintain a constant impedance" - from the product description. Does that make the preferable?
__________________
If I'm not making noise, I'm making something to make noise
  Reply With Quote
Old 11th January 2013, 07:03 AM   #755
ScottG is offline ScottG  United States
diyAudio Member
 
Join Date: Feb 2003
Location: US
Attenuators and Signal Selecters

For the input on the amps.. (tough to find "good" for much less - and they can be improved upon with better resistors in preferred positions).

For the driver - (accepting a transformer or autoformer), just figure out how much resistance you'll need generally and look to Duelund for that value. (..which should be about 1/4 that of a decent transformer). Partsconnexion has them. Mundorf M-Resist Supreme is another option.
__________________
perspective is everything

Last edited by ScottG; 11th January 2013 at 07:24 AM.
  Reply With Quote
Old 12th January 2013, 05:25 PM   #756
diyAudio Member
 
JRKO's Avatar
 
Join Date: Dec 2003
Location: U.K.
Send a message via AIM to JRKO
How does one figure out the needed resistance? buy an lpad and measure i guess

Might the needed figure change? Or would that only be true if I change the bass section (or my mind!!!)
__________________
If I'm not making noise, I'm making something to make noise
  Reply With Quote
Old 13th January 2013, 05:30 AM   #757
diyAudio Member
 
JRKO's Avatar
 
Join Date: Dec 2003
Location: U.K.
Send a message via AIM to JRKO
So just to clear this up......

lpad at speaker level or pot at line level?
__________________
If I'm not making noise, I'm making something to make noise
  Reply With Quote
Old 13th January 2013, 12:54 PM   #758
Elias is offline Elias  Finland
diyAudio Member
 
Elias's Avatar
 
Join Date: May 2003
Location: Where you live
Quote:
Originally Posted by IG81 View Post
IIRC from my measurements, the TF1020 had good 60 dispersion up to ~1.5kHz. An 8" driver might make it a bit higher, if wide and even dispersion is a goal of this project, but otherwise, TF1020 makes it to ~2.5kHz before its first breakup, so you'd be good for your 200Hz-2kHz range with it.

IG

Would you mind posting your measurements of TF1020 ?

Thanks !


- Elias
__________________
Liberate yourself from the illusion of two speaker stereo triangle
Dipole Bass vs Monopole Bass Stereophonic Sound from a Single Loudspeaker 3 Speaker Linear Stereo Matrix Wavelets
  Reply With Quote
Old 13th January 2013, 01:50 PM   #759
Pano is offline Pano  United States
diyAudio Moderator
 
Pano's Avatar
 
Join Date: Oct 2004
Location: Kona, Hawaii
Blog Entries: 4
Quote:
Originally Posted by JRKO View Post
lpad at speaker level or pot at line level?
Both.

You want volume control on all amp channels. That allows you to run the rest of the system at optimum gain levels. You want an L-Pad on the horn drivers to keep the noise and gain of that amp in the right range.

You don't need the variable type of L-Pad, just 2 resistors will do. See here:
L pad calculator - attenuation dB damping impedance
If your horn section is really 109dB/watt, you'll want to bring that down a good bit for almost all amps to keep the S/N ratio good. For adjusting the level to meet the mids or woofer, use the volume control on the amplifier input.

Do NOT use the L-Pad on the woofer section.
__________________
Big Altec Moving Sale!
  Reply With Quote
Old 13th January 2013, 08:20 PM   #760
diyAudio Member
 
JRKO's Avatar
 
Join Date: Dec 2003
Location: U.K.
Send a message via AIM to JRKO
Quote:
Originally Posted by Pano View Post
Both.

You want volume control on all amp channels. That allows you to run the rest of the system at optimum gain levels. You want an L-Pad on the horn drivers to keep the noise and gain of that amp in the right range.

Ok so Vol pot on each amp & lpad on the speaker line of the HF amp - which is the NP ACA in standard form. I visualised having the amps with a clean facia without vol pots, so is there any issue with placing the controls inside or at the rear to keep it tidy? And maybe the lpad at the horn itself - or does that add issues for setup?

Would having both left & right vol pots on the B1 be useful as well?

questions questions questions - tnx Pano Once finished I'll do the voltage test! shouldn't need much!


So the flow is:
pre amp vol x1 or x2
miniDSP vol x1
Bass Amp vol x1
High Amp vol x1 & Stereo Lpad

Thats 5 stages of control!!!!
__________________
If I'm not making noise, I'm making something to make noise

Last edited by JRKO; 13th January 2013 at 08:46 PM.
  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
Transformers: How big is TO big?? dfdye Power Supplies 39 4th September 2010 03:30 PM
Big Toroids & Big Caps K-amps Swap Meet 10 25th June 2009 08:43 PM
Having problems with port size... how big is far too big? fjhuerta Multi-Way 10 30th August 2005 07:20 PM
Big Big hum ??? vlljpior Tubes / Valves 4 26th August 2005 04:53 AM


New To Site? Need Help?

All times are GMT. The time now is 03:04 PM.


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