F4 power amplifier - Page 20 - 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 1st April 2007, 01:49 PM   #191
EUVL is offline EUVL  Europe
diyAudio Member
 
Join Date: Oct 2003
Am I right in saying that in the circuit as shown, the input to the follower circuit (the junction of C1 and C2) has an input resistance of 1047 ohm, as compared to something like 33 ohm of the original F4 circuit ?

Wonder how that affects the bandwidth ?


Patrick

  Reply With Quote
Old 1st April 2007, 05:14 PM   #192
diyAudio Member
 
Join Date: Nov 2002
Location: Cologne, Germany
Is anyone planning to create some pcbs ? I would certainly be interested (as the board design is already in the service manual, I guess it's OK for Nelson if it is a non-commercial effort).

Some questions:

- If I change my route on DIY-amplifier from finishing my AX-100 towards the F4-route: Couldn't I get much more power out of the F4 ? I think my heatsinks have been calculated for 8 devices 044 per channel (source and gain together) with 2 ampere going through each device. heat sink temp is approx. 55 degree celsius, so hot, but still ok. I read now in the service manual, that only 0.53 amps goe through the devices: So why not more if heatsinks allow it ? I thought Nelson is a big fan of more current per device.

- My experiences with jfet: These little devices behave quiet a bit different, even if it is the same type, depending on the circuit and the Iss max. So what is the selection-criteria on the 2sk370 and the 2sj108 ? Both are out there in versions GR: 2.6~6.5 mA, BL: 6.0~12 mA, V: 10~20 mA, but I guess it is even better to know what the ideal value is and to select accordingly. Nelson, you said they run 5ma: Is that Idss max ?

- On the capacitor-coupling: What is the smallest value really needed ? 220u is an electrolytic. I really had to have that in the signal chain. so, could this one be smaller and be at least a MKP-Highend-version like Mundorf Supreme ?

- Last point: I would bet quiet a bit on the fact that a LcLc-power-supply would make a significant difference in sound to this standard crc-supply. Steen, any chance in testing this ?

Best Regards

Frank
  Reply With Quote
Old 1st April 2007, 07:33 PM   #193
diyAudio Member
 
mpmarino's Avatar
 
Join Date: Jun 2004
Location: Crunchville, where I don't fit in.
Default F4 chassis - aleph style

Not close to done - my F4 chassis in the works. Coffins are no fun anymore
Attached Images
File Type: jpg f41 (medium).jpg (29.6 KB, 2246 views)
__________________
Crazy Yankee.
  Reply With Quote
Old 1st April 2007, 07:34 PM   #194
diyAudio Member
 
mpmarino's Avatar
 
Join Date: Jun 2004
Location: Crunchville, where I don't fit in.
front
Attached Images
File Type: jpg f42 (medium).jpg (28.1 KB, 2011 views)
__________________
Crazy Yankee.
  Reply With Quote
Old 1st April 2007, 09:46 PM   #195
steenoe is offline steenoe  Denmark
diyAudio Member
 
steenoe's Avatar
 
Join Date: Mar 2004
Quote:
Couldn't I get much more power out of the F4 ?
Hi Frank. You can easily adjust it to get more amperes/heat, you might need to adjust the value of R9 though. R9 in mine (and cvillers) are about 6K. The schematic says 10K.
Quote:
Last point: I would bet quiet a bit on the fact that a LcLc-power-supply would make a significant difference in sound to this standard crc-supply. Steen, any chance in testing this ?
I agree. When I build the monoblocks, I will use a CLC filter, with big Rifa's Unfortunately, I wont be able to test the F4 with a different supply for a while. I am pretty hung up in the nearest future.
Keep in mind that the F4 needs a decent preamp, especially if your speakers arent very effecient. One could get dissapointed about the soundlevel. I would also like to mention that all the other amplifiers are still as good as before ZenV9, Aleph-X, Babbelfish's and so on, are still superb sounding amps. The F4 is just a further step forward sonically, at least to my ears Here are the words that made me want to try it: http://www.diyaudio.com/forums/showt...18#post1151518 Together with Mr. Pass remark in the F4 pdf that this could be the best sounding amp
Who can resist building one? Not me

Quote:
Not close to done - my F4 chassis in the works.
Nice big heatsinks Looks cool

Steen
  Reply With Quote
Old 1st April 2007, 10:21 PM   #196
diyAudio Member
 
Peter Daniel's Avatar
 
Join Date: Jul 2002
Location: Toronto, Canada
Send a message via AIM to Peter Daniel
One needs to consider the environment in which the amp is being used.
If you compare all amps with a preamp, then certainly F4 may have biggest advantage for performance.

However, I like F3 because I can use it without a preamp (source connected directly, no attenuator) or with a passive preamp (12db of gain is still enough for me).

Untill I was forced to use it with an active preamp, F3 was not appealing to me that much and I kept it on a side for almost half a year. But then, I switched to a source with higher output level and F3 can be now used with passive attenuator, and in a configuration when the output caps can be minimized or bypassed completely (3 way active system). Now, that brings the best out of it and I don't think F4 would be much of a contender here as removing the active preamp from a system can be actually the biggest advantage.
__________________
www.audiosector.com
“Do something really well. See how much time it takes. It might be a product, a work of art, who knows? Then give it away cheaply, just because you feel that it should not cost so much, even if it took a lot of time and expensive materials to make it.” - JC
  Reply With Quote
Old 1st April 2007, 11:13 PM   #197
diyAudio Member
 
mpmarino's Avatar
 
Join Date: Jun 2004
Location: Crunchville, where I don't fit in.
Lets take a look at what happened in car audio some 15 years ago. The competition circuit (Iasca) helped to make a lot of changes for the better. Competitors realized that driving the signal as hard as possible and gaining the amplifiers down greatly improved things. Better S/N ratio, less need for megabuck cables, overall better sound. Fortunately the head unit manufacturers responded by making sources with upwards of 12v unclipped at the RCA jack. The whole dang thing got way way better. I think it is the most important thing that happened in car audio.

I don't do cars anymore - did for 15 years professionally though. Heck, I was putting 8" pro midbases in kickpanels years before anything like that made it to a magazine. It was fun.

Granted, a car is not a living room unless you happen to drive a Bentley. BUT I wonder if the current state of affairs shouldn't be improved. I know - there are standards CD - 2v out/ pre - 5v out/ amp- whatever gain it happens to have. These things came about a long time ago and really never nudged.

I think with DIY we may realize a better way in this regard. Nelson, thanks for bringing this forward
__________________
Crazy Yankee.
  Reply With Quote
Old 1st April 2007, 11:40 PM   #198
The one and only
 
Nelson Pass's Avatar
 
Join Date: Mar 2001
I think the self-appointed "home theater standards" guardians
did the audio world a big disservice by coming up with a 30 dB
gain figure. That means more noise to be picked up on the way
to the amplifier, through RCA cables, no less.

  Reply With Quote
Old 2nd April 2007, 08:51 AM   #199
Vix is offline Vix  Yugoslavia
diyAudio Member
 
Vix's Avatar
 
Join Date: Nov 2003
Location: Somewhere on Planet Earth
Quote:
Originally posted by Peter Daniel
Untill I was forced to use it with an active preamp, F3 was not appealing to me that much and I kept it on a side for almost half a year. But then, I switched to a source with higher output level and F3 can be now used with passive attenuator, and in a configuration when the output caps can be minimized or bypassed completely (3 way active system). Now, that brings the best out of it and I don't think F4 would be much of a contender here as removing the active preamp from a system can be actually the biggest advantage.
I fully agree. When I built Zen V9, I was using it with the Bride of Zen pre. It was ok, but I had a feeling that something was missing. Until a few days ago, when I built a tube buffer. Wow! Only then I heard how good Zv9 can sound, albeit I can't play it very loud. Maybe I will reduce the amount of feedback on Zv9 or remove it completely and run it as a current amp.

Regards,

Vix
  Reply With Quote
Old 2nd April 2007, 05:14 PM   #200
MiiB is online now MiiB  Denmark
diyAudio Member
 
Join Date: May 2005
Location: Denmark
When playing with this circuit i noted that the capacitors driving the mosfets are rather large. I reduced size to 22uF to see what impact it had on the lower end frequency response. Taking the low drive current available through the Jfets into account, these two capacitors must be of ultimate quality, hence the desire for reducing the size. Anyway at 22 uF the frequency response extends to app 5 Hz and no phaseshift above 10 Hz.
Has anyone else been working with this issue??
  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 11:49 PM
Power transformers versus amplifier output power..what is your option? destroyer X Solid State 38 9th May 2009 06:23 PM
McIntosh Power Amplifier Power Guard johnnyrt Solid State 2 23rd August 2007 11:22 PM
Output power for a power amplifier Progg70 Solid State 33 10th September 2006 09:44 AM
Amplifier 3000 Wats Rms Power + Smps Higcht Power Bestiality MARAVILLASAUDIO Class D 1 5th November 2004 05:06 PM


New To Site? Need Help?

All times are GMT. The time now is 09:34 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