F4 power amplifier - Page 93 - diyAudio
Go Back   Home > Forums > Amplifiers > Pass Labs

Pass Labs This forum is dedicated to Pass Labs discussion.

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 July 2007, 07:21 PM   #921
diyAudio Member
 
Join Date: Aug 2004
Location: Chicago area
Default Listening

First, a disclaimer. My system has changed since the F1 and F2 have been in it, and my Alerions are on loan so making a comparison based upon memory is unfair.

Right now I have Lowther PM6A's with Ticonal G magnets and silver voice coils in an open baffle. A Xono and X1 are the pre's, and XVR1 is my electronic crossover. An Eminence Pro Sound 15 inch is acting as the woofer, and cuts in at around 150 hz. The F4 was used only for the Lowther, and only in the unbalanced mode.

Plug it in, turn it on. Proper warm up takes 1/2 hour. There is a noticeable upper midrange glare during the warmup period. Mostly gone after 10 minutes, and after 30 minutes it is time for serious listening.

This amplifier has extremely natural dynamics - something most people don't even think about in music reproduction, but is so important. Instruments come into the limelight during solos, and then fade into the background when they are done. This is as they do during live play. Many high end amplifiers compress the music to increase detail and unnatural imaging - not here. This natural dynamic range honors the emotion of the music.

Highs are extended and well defined. The midrange has that magic that is usually attributed to great tube amps. You hear more of the texture of voices Overlays and multiple singers are easily separated for what they are. Following the individual voices is easy. There is a little sweetness in this amp, enough to make it a joy to listen to without it adding unnatural colorations. I could be wrong on this, the other amps may have just been taking some of the sweetness out of the music. Whatever the case, this sounds right.

Imaging is natural. Front to rear, side to side, but without the etched quality of some amplifiers. Closer to what you hear on the stage. No fake detail, but nothing taken from the performance.

The amp mostly disappears and hides, leaving the music behind. This amp is better than 99% of the speakers out there. What you here may be more the limitation on your speakers than this amp.

Cons: When I listen intently with the lights off, those blue LEDS are too bright. Nelson says an additional resistor in line with the LED reduces this effect.

Having followed this thread for awhile I note a number of people trying to improve the amp before building it. Kinda reminds me of someone saying that if they just had the perfect golf club they would beat Tiger Woods all the time. Having a "perfect" tool (and we know that simulations are not perfect) and having the ability to wield that tool effectively are different things. Nelson is a master, like Tiger, and you would be far better served to buy (or build) this first. Then you will have the proper yardstick to measure success by.

Have some fun with this one. I have some more listening to do.
__________________
Jon Ver Halen
Lowther-America
  Reply With Quote
Old 21st July 2007, 08:29 PM   #922
Netlist is offline Netlist  Belgium
diyAudio Moderator Emeritus
 
Netlist's Avatar
 
Join Date: Jan 2003
Sweet...

/Hugo
  Reply With Quote
Old 22nd July 2007, 09:32 PM   #923
steenoe is offline steenoe  Denmark
diyAudio Member
 
steenoe's Avatar
 
Join Date: Mar 2004
Default Re: Listening

Quote:
Originally posted by Jon Ver Halen
First, a disclaimer. My system has changed since the F1 and F2 have been in it, and my Alerions are on loan so making a comparison based upon memory is unfair.

Right now I have Lowther PM6A's with Ticonal G magnets and silver voice coils in an open baffle. A Xono and X1 are the pre's, and XVR1 is my electronic crossover. An Eminence Pro Sound 15 inch is acting as the woofer, and cuts in at around 150 hz. The F4 was used only for the Lowther, and only in the unbalanced mode.

Plug it in, turn it on. Proper warm up takes 1/2 hour. There is a noticeable upper midrange glare during the warmup period. Mostly gone after 10 minutes, and after 30 minutes it is time for serious listening.

This amplifier has extremely natural dynamics - something most people don't even think about in music reproduction, but is so important. Instruments come into the limelight during solos, and then fade into the background when they are done. This is as they do during live play. Many high end amplifiers compress the music to increase detail and unnatural imaging - not here. This natural dynamic range honors the emotion of the music.

Highs are extended and well defined. The midrange has that magic that is usually attributed to great tube amps. You hear more of the texture of voices Overlays and multiple singers are easily separated for what they are. Following the individual voices is easy. There is a little sweetness in this amp, enough to make it a joy to listen to without it adding unnatural colorations. I could be wrong on this, the other amps may have just been taking some of the sweetness out of the music. Whatever the case, this sounds right.

Imaging is natural. Front to rear, side to side, but without the etched quality of some amplifiers. Closer to what you hear on the stage. No fake detail, but nothing taken from the performance.

The amp mostly disappears and hides, leaving the music behind. This amp is better than 99% of the speakers out there. What you here may be more the limitation on your speakers than this amp.

Cons: When I listen intently with the lights off, those blue LEDS are too bright. Nelson says an additional resistor in line with the LED reduces this effect.

Having followed this thread for awhile I note a number of people trying to improve the amp before building it. Kinda reminds me of someone saying that if they just had the perfect golf club they would beat Tiger Woods all the time. Having a "perfect" tool (and we know that simulations are not perfect) and having the ability to wield that tool effectively are different things. Nelson is a master, like Tiger, and you would be far better served to buy (or build) this first. Then you will have the proper yardstick to measure success by.

Have some fun with this one. I have some more listening to do.
Jon; I could write pages up and down about how you should use the F4 and how wonderfull it sounds, but I wont! I will only tell you to; listen to it with a pair of full-rangers You should be able...? Man, it will give you the most coherent sounding music, that you can dream about!!

Steen
  Reply With Quote
Old 22nd July 2007, 09:52 PM   #924
diyAudio Member
 
Join Date: Aug 2004
Location: Chicago area
Hi Steen:

Quote:
Jon; I could write pages up and down about how you should use the F4 and how wonderfull it sounds, but I wont! I will only tell you to; listen to it with a pair of full-rangers You should be able...? Man, it will give you the most coherent sounding music, that you can dream about!!
I am going from 150 hz to 20 kHz with my Lowther. There is not a whole lot more range for me to cover with that one driver. The last 100 hz or so does sound a little tighter in a back loaded horn configuration, but what I have is very, very musical.

And yes, it is coherent, lively, fun, musical. Just a great amp.

I will be off for a week, so if anyone else has comments or questions expect a long wait before I reply.
__________________
Jon Ver Halen
Lowther-America
  Reply With Quote
Old 23rd July 2007, 06:25 PM   #925
The one and only
 
Nelson Pass's Avatar
 
Join Date: Mar 2001
Default Re: Listening

Quote:
Originally posted by Jon Ver Halen
Cons: When I listen intently with the lights off, those blue LEDS are too bright. Nelson says an additional resistor in line with the LED reduces this effect.
OK, OK. So I've increases the resistor from 10K to 33K in
production.

  Reply With Quote
Old 23rd July 2007, 07:41 PM   #926
Variac is offline Variac  United States
diyAudio Editor
 
Variac's Avatar
 
Join Date: Dec 2001
Location: San Francisco, USA
There's the advantage of the kitchen table approach- instant response.

Probably Nelson didn't even have to have a committee meeting to decide this! Possibly he had to walk to the warehouse for the new resistors, but I doubt it!
  Reply With Quote
Old 23rd July 2007, 09:05 PM   #927
diyAudio Member
 
Join Date: Feb 2001
Location: Columbia, SC
Default Re: Listening

Quote:
Originally posted by Jon Ver Halen


Cons: When I listen intently with the lights off, those blue LEDS are too bright. Nelson says an additional resistor in line with the LED reduces this effect.



I have a buddy who wants total, absolute darkness in his listening room. I've suggested increasing resistors, detaching the lead to the LED, switch for the power light, ignoring the lights, you name it.
His solution is ordinary black vinyl electrical tape over the LEDs.
Doesn't stick all that well to anodized aluminum, leaves a gummy residue, and looks like hell. He doesn't care.
To each his own.

Grey
  Reply With Quote
Old 23rd July 2007, 09:17 PM   #928
diyAudio Member
 
carawu's Avatar
 
Join Date: Jul 2003
Default Re: Re: Listening

Quote:
Originally posted by GRollins



I have a buddy who wants total, absolute darkness in his listening room. I've suggested increasing resistors, detaching the lead to the LED, switch for the power light, ignoring the lights, you name it.
His solution is ordinary black vinyl electrical tape over the LEDs.
Doesn't stick all that well to anodized aluminum, leaves a gummy residue, and looks like hell. He doesn't care.
To each his own.

Grey

I like this behavior!

LG Carsten
  Reply With Quote
Old 23rd July 2007, 09:39 PM   #929
The one and only
 
Nelson Pass's Avatar
 
Join Date: Mar 2001
The new resistor value for the led is not part of the freshly
posted revised manual to be found as a pdf file in

www.passlabs.com/np

  Reply With Quote
Old 24th July 2007, 06:20 AM   #930
lykkedk is offline lykkedk  Denmark
diyAudio Member
 
Join Date: Dec 2002
Location: Denmark, Fredericia
Send a message via MSN to lykkedk
Thanks NP, for the new schematics...

Actually, i am just in for testing 1 channel (1 of 4), today, and see, the newest schematic of the pcb/powersupply design, and how the thermistors are attached, just how i did it on my 'connection' pcb.
I am planning on replacing the resistor value R3, R4, R8 + gate resistors to they're new values... But later on...
I see, that the powerconsuption is a little higher now, and that the bias has changed a bit. Maybe someone could explain the advantages of theese changes ???

I would also, like to know if theese connection, i am planning is right :

1. Singleended input : (+ in / GND). And jumpers in XLR in - to GND. Loudspeaker between out and GND.

2. Balanced Mono : XLR in +/-, Loudspeaker between + out / - out.

3. Bridged Mono : Singleended input + connected to booth channels ???

I am planning to make all, theese possibilities, but it's a bit hard for me, to figure out how to do this excatly Anyone have a schematics of how to do this right ?

Jesper...
__________________
/// got to catch up again ///
  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
Rockford Fosgate Power 20001 bd amplifier power rating?? pachoorion Car Audio 8 8th May 2011 10:49 PM
Power transformers versus amplifier output power..what is your option? destroyer X Solid State 38 9th May 2009 05:23 PM
McIntosh Power Amplifier Power Guard johnnyrt Solid State 2 23rd August 2007 10:22 PM
Output power for a power amplifier Progg70 Solid State 33 10th September 2006 08:44 AM
Amplifier 3000 Wats Rms Power + Smps Higcht Power Bestiality MARAVILLASAUDIO Class D 1 5th November 2004 04:06 PM


New To Site? Need Help?

All times are GMT. The time now is 01:33 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