NAIM NAP 140 CLONE vs JLH 1996 Class A (30W per Channel (4ohm)) - Page 2 - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

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 2008, 03:56 PM   #11
diyAudio Member
 
jacco vermeulen's Avatar
 
Join Date: Oct 2004
Location: At the sea front, Rotterdam or Curaçao
Send a message via Yahoo to jacco vermeulen
90dB + 10dB = 100dB, 103dB for a pair.
Makes 93dB at 3m, minus 20dB for peaks leaves 73dB continuous.
Not all that bad.

There's also the Ahem-LH to consider.
__________________
The buck stops Here
  Reply With Quote
Old 22nd July 2008, 02:46 AM   #12
Banned
 
Join Date: Nov 2006
Andrew
I have told you they have been designed by Geoff Moss to run at 30W per channel into a 4 ohm load. He has given me the necessary instructions to achieve this, so please don't ask that question again.
Anyway I appreciate any comments you would like to make between the 2 amps.
Have you actually heard these 2 amps?

Destroyer X
Thanks for the advice, I agree with what you have said, however it would be nice to hear some opinions as I am not sure I have the time or money to build both as I still also have to build a preamp.
  Reply With Quote
Old 22nd July 2008, 02:46 AM   #13
Banned
 
Join Date: Nov 2006
Just some more information to assist in giving advice:
I am a bass player, so obviously the quality of bass sound and tone is number 1 priority followed by drums and percussion and then guitar/saxophone and then other instruments.

Also I notice when playing electric bass I find I prefer the tone when playing through a valve preamp into solid state amp (integrated hybrid units) such as Eden or Trace Elliot.

Thanks again for all the advice so far
  Reply With Quote
Old 22nd July 2008, 07:58 AM   #14
AndrewT is online now AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Quote:
Originally posted by thanh1973
designed by Geoff Moss to run at 30W per channel into a 4 ohm load.
Finally.
We now know which JLH you want compared.
Why make it so hard for those who might be able to help with your enquiry?
__________________
regards Andrew T.
  Reply With Quote
Old 22nd July 2008, 02:42 PM   #15
sreten is offline sreten  United Kingdom
diyAudio Member
 
Join Date: Nov 2003
Location: Brighton UK
Hi,

Do we assume your speakers are 4 or 8 ohm ?

If 8 then its a 15W amplifier, if 4 then you sure you have enough current ?

FWIW the lowish powered Class A amplifiers I've heard that cannot
do Class B struggle with the bass end, (sugden and kelvin labs).
They are like the JLH, they severely current limit in one direction.
also see the "Death of Zen", similar to the JLH.

If your considering both I'd say you need a proper push pull amplifier
heavily biased into class A rather than the "white cathode follower"
arrangement of the above amplifiers.

In fact by reducing the voltage rails and wacking up the bias current
in a Naim style amplifier that is what you would actually get, assuming

http://www.neilmcbride.co.uk/jknamps.html

Is representative of the NAP 140.

/sreten.
  Reply With Quote
Old 22nd July 2008, 05:02 PM   #16
sreten is offline sreten  United Kingdom
diyAudio Member
 
Join Date: Nov 2003
Location: Brighton UK
Hi,

I missed the Usher 2.5 way 4 ohm bit.

http://www.zalytron.com/Schematics/usher2w5s3.pdf

One could argue not very class A friendly and in fact only 87dB
or so per real watt (as opposed to 90dB or so for a 4 ohm watt).

/sreten.
  Reply With Quote
Old 23rd July 2008, 01:11 AM   #17
diyAudio Member
 
Join Date: Dec 2002
Location: Houston
Default 2.5 Way is great.

One trick I am trying with my 2.5 way Quad 22L2 is passive biamping. Use a stereo amp per speaker, both channels driven full range.
One channel drives the 2 way section, the other channel drives just the 0.5 or bass driver. Since most have a slow roll off on the bass driver the fullrange power is not wasted. The other side is full range to begin with.
Not every setup is the same, but in my mind, this is a perfect application. This also will address the current delivery issues mentioned. The two drivers handing the bass are in parallel from a couple hundred Hz down. So they will be ABOUT 8 ohm if split.
My amps have limited voltage swing, 35 volt rails, so maybe 30 volts rms. But should be able to dump 20 amps. It still makes a difference in the mids and in the bass.
The damping factor is increased, and maybe moving the low pass filter for the bass driver out improves the mids.
If you have the resources to build two identical steeo amps, and the Ushers are biwireable, this might float your boat.

George
__________________
Cheapest is bestest
  Reply With Quote
Old 23rd July 2008, 09:13 PM   #18
Banned
 
Join Date: Nov 2006
Look at pdf file for speaker sensitivity (ie roughly 90dB).
Yes I agree not very Class A friendly, however with Geoff Moss' help I have been given the necessary information to build a Class A amplifier designed specifically for a 4ohm load at 30W per channel.
Any way I will probably build both but I intend on building the JLH first. I have now received the PCBs and will start ordering the necessary parts.
Attached Files
File Type: pdf usher2w5s1 sensitivity.pdf (77.0 KB, 121 views)
  Reply With Quote
Old 24th July 2008, 09:27 AM   #19
AndrewT is online now AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Hi,
that sensitivity graph says dB/W for 8ohms.
I suspect that is telling you that it is really dB/2.8V for the speaker load.
Since the speaker is rated as a 4ohm load that brings the true sensitivity down to 87dB/W/m.
30W into 4ohms is +15dBw and gives a peak SPL of about 102dB. This is low but OK. Certainly worth pursuing.
__________________
regards Andrew T.
  Reply With Quote
Old 24th July 2008, 09:32 PM   #20
Banned
 
Join Date: Nov 2006
Hi Andrew T
I still think these speakers are rated at 90dB/W/m. Check out the link below, of some commercially made speakers using the exact same drivers in 2.5 way set up. (look at the specs tab)
http://www.usheraudiousa.com/product...series/cp-6371

For those that are interested, below is an extract from Geoff's site:

"When used with conventional speakers, this circuit can deliver over 40W provided the supply rail voltage and quiescent current are selected to suit a specific load impedance. The supply rail voltage needs to be a couple of volts higher than the peak output voltage swing and the total quiescent current should be about 0.7 times the maximum output current. The power dissipated in each output transistor (supply rail voltage times half the quiescent current) should be limited to about 40 to 45W, assuming decent sized heatsinks are used (0.6 to 0.8degC/W per transistor)."
  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
Build NAIM clone Beardini Solid State 45 29th January 2013 11:12 AM
Opinions on Naim Clone - H140 Kit - www.hifidiy.net dine1967 Solid State 2 28th December 2008 08:10 PM
My Class D DIY - gainclone clone neil_kaye Class D 13 13th March 2006 02:33 PM


New To Site? Need Help?

All times are GMT. The time now is 08:10 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