Go Back   Home > Forums > >

Solid State Talk all about solid state amplification.

Hifisonix kx-Amplifier
Hifisonix kx-Amplifier
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
Old 11th November 2018, 10:59 AM   #11
maty tinman is offline maty tinman  Spain
diyAudio Member
 
maty tinman's Avatar
 
Join Date: Apr 2012
Location: Tarragona (Spain)
Its 50 W per channel with the original sx amp supplies - about 60 watts on the slightly higher rails for class A

page 21
Quote:
Output power: >28 W peak class A into 8 Ωs = 15 W RMS into 8 Ωs class A; 50 W RMS into 4 Ωs class AB; 95W RMS class AB into 2 Ωs;

Standing current Class A mode: 1.2 amps (600 mA per output pair); standing current class AAB mode: 600 mA (300 mA per pair) +-20%

Distortion (measured): typically 0.006% at 15W into 8 Ωs; 0.015% at 50 W class AB into 4 Ωs; <0.1% at 90W into 2 Ωs

Slew Rate: 140 V/us (10%~90%, symmetrical)
If the standing current is the half in class AAB, the dissipated power should not be 30 watts by channel?
__________________
"Comment is free, but facts are sacred" - C. P. Scott *** 40 years of the Spanish Constitution, My musical celebration
  Reply With Quote
Old 11th November 2018, 11:12 AM   #12
maty tinman is offline maty tinman  Spain
diyAudio Member
 
maty tinman's Avatar
 
Join Date: Apr 2012
Location: Tarragona (Spain)
Default SPL

http://www.doctorproaudio.com/doctor...n.htm#calc_spl

Calculators / Audio / Acoustics / SPL


SPL: KX-amplifier-KEF-LS50-83dB-15watts

Click the image to open in full size.

with KEF Q100 (85 dB) -> 90.2 dB. In phase + 3dB: 93.2 dB.

SPL: KX-amplifier-speaker-89dB-15watts

Click the image to open in full size.
__________________
"Comment is free, but facts are sacred" - C. P. Scott *** 40 years of the Spanish Constitution, My musical celebration

Last edited by maty tinman; 11th November 2018 at 11:16 AM.
  Reply With Quote
Old 11th November 2018, 12:46 PM   #13
bambadoo is offline bambadoo  Norway
diyAudio Member
 
Join Date: Feb 2003
Location: West Coast of Norway
Crap - so happy with the sx.. Just have to build this.
  Reply With Quote
Old 11th November 2018, 01:04 PM   #14
Vrystaat is offline Vrystaat  South Africa
diyAudio Member
 
Join Date: Jan 2012
Location: Bloemfontein
Bonsai, good to see you are busy again !!
__________________
Regards
Jan
  Reply With Quote
Old 11th November 2018, 01:14 PM   #15
xrk971 is offline xrk971  United States
Got Foam?
diyAudio Member
 
xrk971's Avatar
 
Join Date: Oct 2012
Location: Metro DC (Virginia)
Hifisonix kx-Amplifier
Welcome back Bonsai! Nice amp design, and another one for us to try out for Class A designs. I am curious how this compares to Hughs Alpha 20 (or 35 Omega or 55w Alpha BigBoy). Also interested to find you listen to LS50s as I had a chance to audition their self powered and DSP w variant the other day when I was in Germany. They sounded very nice for 5in bookshelf speakers.
__________________
XRKaudio https://www.etsy.com/shop/XRKAudio
  Reply With Quote
Old 11th November 2018, 01:35 PM   #16
Bonsai is offline Bonsai  Europe
diyAudio Member
 
Bonsai's Avatar
 
Join Date: Jul 2003
Location: Europe
Hifisonix kx-Amplifier
Thanks guys - I've been busy this last year!
  Reply With Quote
Old 11th November 2018, 01:42 PM   #17
Bonsai is offline Bonsai  Europe
diyAudio Member
 
Bonsai's Avatar
 
Join Date: Jul 2003
Location: Europe
Hifisonix kx-Amplifier
Maty, the kx-Amp delivers 50W into 4 ohms quite easily. Also, remember the peak class A power is about 25W (same for sx-Amp BTW). So, there is plenty of power to handle crescendo's. As mentioned on the website, of you want rock concert hall levels from a class A amp like this in a large listening space, you need to use more efficient speakers, or you need to constrain your listening space appropriately. If you shop around, you can find plenty of speakers at 93dB~96dB or more efficiency. I bought my LS50's to do an audio show after auditioning them - they were driven by a 100W amp on that show. But, they sound good even with a low power amp like this one.
  Reply With Quote
Old 11th November 2018, 02:21 PM   #18
Mark Johnson is offline Mark Johnson  United States
diyAudio Donor
diyAudio Member
 
Mark Johnson's Avatar
 
Join Date: May 2011
Location: Silicon Valley
Hifisonix kx-Amplifier
I wish the square wave tests (page 25) weren't presented with oscilloscope bandwidth limiting turned on. There might be a bit of overshoot or underdamped ringing, which BWLIMIT prevents us from seeing.

Just barely visible is a smidgen of overshoot: the smoothed, BWLIMITed yellow trace just barely overshoots enough to kiss the upper dotted line. Then it recovers from overshoot and settles down to its final asymptotic value. Click on the white "X" at lower left to see the image full size and undistorted. The overshoot is also visible in the zoomed out (20usec/div) picture on the same page.

I also wish there were 3A or 5A "catch diodes" across the Zobel networks, to protect the output transistors when clipping into crazy reactive loads. And I wish the "OMG a rail is dead" safety diodes {Cordell section 15.3, p.325} D2 and D3 had a continuous DC current rating higher than fuses F2 and F3. I personally prefer to use the 10A04 thru hole diode in those positions; I don't mind paying 2 x $0.76 to buy them.

_
Attached Images
File Type: png BWLIMIT.png (78.9 KB, 649 views)
  Reply With Quote
Old 11th November 2018, 02:33 PM   #19
fab is offline fab  Canada
diyAudio Member
 
fab's Avatar
 
Join Date: Mar 2004
Location: Canada
Hifisonix kx-Amplifier
Good project Bonsai
As usual you provide a very good informative manual and I appreciate that peoples can also learn in the process of diy.
I was impressed when I built your NX amplifier with similar topology as the SX or KX. The depth of the soundstage and the dynamic is special. It has motivated me into continuing experimentation of the “CFA” topology..

Fab
__________________
My stuff USSA, FSSA, USSPA: https://fabaudio.online
  Reply With Quote
Old 11th November 2018, 05:12 PM   #20
maty tinman is offline maty tinman  Spain
diyAudio Member
 
maty tinman's Avatar
 
Join Date: Apr 2012
Location: Tarragona (Spain)
Bonsai, trust me, my KEF Q100 with my tweaks sound very well. They have a very similar frequency response than KEF LS50, front bass-reflex and 49 Hz at -3 dB. More sensitivity (2 dB) and minimum impedance (4.7 Ohms).

KEF saved on the furniture, with a thin DM. The 5" coaxial is very good (the 6.5", at least the old, NO).

They love power. I modified the bias of my AV Marantz SR4500, now is more high -> better sound. Maybe at low volume, in near field (with the PC), it works like class A, maybe.

My idea is the ALPHA Lender preamp + very clean power amp. Wich power amp? I do not know yet.
__________________
"Comment is free, but facts are sacred" - C. P. Scott *** 40 years of the Spanish Constitution, My musical celebration
  Reply With Quote

Reply


Hifisonix kx-AmplifierHide this!Advertise here!
Thread Tools

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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Boss NXD3500 car amplifier hooked to an Onkyo 7.2ch home amplifier Evolver Class D 1 13th March 2020 11:48 AM
Hypex SMPS400 + 2x UCD180 wiring (DC error, Auto Amplifier Enable, Amplifier Standby) maxw Class D 48 26th May 2017 07:47 PM
hifisonix small signal class a? mlackey Headphone Systems 1 1st January 2016 03:16 AM
Motional feedback amplifier based on Philips 40 wats amplifier 1970s sanbadgujar Solid State 14 13th October 2013 02:35 PM
JLH Chiarra or Hifisonix Class A buffer? MondyT Headphone Systems 2 30th January 2013 05:14 PM


New To Site? Need Help?

All times are GMT. The time now is 09:37 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2021 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2021 DragonByte Technologies Ltd.
Copyright ©1999-2021 diyAudio
Wiki