small/excellent amp recommendation for highs on active system - 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 2nd February 2014, 10:40 PM   #1
laplace is offline laplace  Australia
diyAudio Member
 
Join Date: Jan 2014
Default small/excellent amp recommendation for highs on active system

Hi all,

I'm building a 3-way active system at the moment and using a whole pile of LM3886 for the mids and tweeters. While they're good, I know that one can build something better and I'd like to do that as a next step in upgrading it, at least for the front speakers.

So: do you have recommendations for solid-state amps with the following sort of characteristics:
- Class AB[1]
- about 50W RMS into 8R
- can run from 35+35V DC rails (I have 25+25 transformers that I will reuse)
- I would like to avoid boosted+regulated input+VAS supply but will do it if necessary, just not sure where the extra hardware will go yet...
- the best possible (quantifiable!) performance, particularly at higher frequencies
- integrated turn-on mute and DC protection if possible[2]
- at most 100mm of heatsink length per channel[3], so a small count of high current transistors might be good
- don't worry about the LF amps, that bit is easy[4]

Should I just make a (variant of) Blameless or Low-TIM ? They're both pretty old designs and I haven't been paying any attention to amplifier design in the last 15 years; have they been significantly improved-upon?

Links to schematics: good. Links to PCBs and/or kits: great. Either way, something well-proven from measurement and not just simulation. I can do custom PCB layouts to meet the 100mm requirement but don't want to be tweaking schematics of proven designs and probably making them worse.


thanks...

[1] I realise that Class A is kind of an obvious thing to consider here, but space and power requirements forbid it. I have many channels and limited physical room (rack cases) to house the amps and really don't want a rackfull of class As hoovering away, heating up the lounge room.

[2] I intend to directly connect midrange and tweeter drivers to these amps and would like to have the amplifier design be safe enough in turn-on/off behaviour that I can avoid any series protection capacitors, etc.

[3] again with the rack cases and heatsink fan tunnels. Heat dissipation capacity is kind of huge but the PCB for each amp needs to be about 100mm long so that I can physically put channels in a single case (with the LF amps!) to replace the 3886s.

[4] I have plenty of good designs in the 100-150W RMS range to choose from to run the LF drivers. It's a rare modern amp design that doesn't have incredibly good performance for all frequencies below 500Hz...
__________________
Open-Source F/Stop Timer
on flickr
  Reply With Quote
Old 2nd February 2014, 10:56 PM   #2
diyAudio Member
 
jkuetemann's Avatar
 
Join Date: Dec 2010
Location: Paris, Ontario
Perhaps a VSSA variant? I've built a few and find them to be a really nice sounding amplifier well suited to your operating parameters. There are several threads related to these little amps, one of them my own (shameless plug).
__________________
---Jason Kuetemann---
When the student is ready, the master appears.
  Reply With Quote
Old 2nd February 2014, 11:52 PM   #3
diyAudio Member
 
abraxalito's Avatar
 
Join Date: Sep 2007
Location: Hangzhou - Marco Polo's 'most beautiful city'. 700yrs is a long time though...
Blog Entries: 101
Send a message via MSN to abraxalito Send a message via Yahoo to abraxalito Send a message via Skype™ to abraxalito
TDA1514 might fit the bill - looks to me to have more potential than LM3886, despite still being a chipamp. Needs to be bridged to hit your 50W/8R target.
__________________
No matter if we meanwhile surrender every value for which we stand, we must strive to cajole the majority into imagining itself on our side - Everett Dean Martin
  Reply With Quote
Old 3rd February 2014, 12:56 AM   #4
bimo is offline bimo  Indonesia
diyAudio Member
 
bimo's Avatar
 
Join Date: Sep 2010
Location: Depok, West of Java
Quote:
Originally Posted by jkuetemann View Post
Perhaps a VSSA variant? I've built a few and find them to be a really nice sounding amplifier well suited to your operating parameters. There are several threads related to these little amps, one of them my own (shameless plug).
I suggest VSSA variant too. It is much better than LM3886 or other amplifier with more complex design (subjectively) in high frequency.
  Reply With Quote
Old 3rd February 2014, 02:05 AM   #5
laplace is offline laplace  Australia
diyAudio Member
 
Join Date: Jan 2014
By VSSA, you mean one of these? Frankly it looks way too simple to be particularly good; has anyone measured a built VSSA to show that its THD+IMD+N is in the same ballpark as Blameless and similar? If true, that would be really awesome.

Has anyone built a "mini badger" low-power version of the honey badger? I'm looking for that level of quality but obviously don't need nearly as much silicon on the output.

The TDA1514 specs for THD+N look very good. I'd have to rebuild my power supplies though and it will do only 28W into 8R. The -3dB probably doesn't really matter but buying new transformers is annoying/expensive, and I don't see the chips listed at Mouser or Farnell.
__________________
Open-Source F/Stop Timer
on flickr
  Reply With Quote
Old 3rd February 2014, 02:43 AM   #6
diyAudio Member
 
abraxalito's Avatar
 
Join Date: Sep 2007
Location: Hangzhou - Marco Polo's 'most beautiful city'. 700yrs is a long time though...
Blog Entries: 101
Send a message via MSN to abraxalito Send a message via Yahoo to abraxalito Send a message via Skype™ to abraxalito
I reckon you can use your existing 25+25 trafo to give a single ended supply, suitable for running two bridged TDA1514s. This means your smoothing caps going in parallel rather than in series.

You're right the chips aren't current production but the secondary market has plenty.
__________________
No matter if we meanwhile surrender every value for which we stand, we must strive to cajole the majority into imagining itself on our side - Everett Dean Martin
  Reply With Quote
Old 3rd February 2014, 03:19 AM   #7
diyAudio Member
 
jkuetemann's Avatar
 
Join Date: Dec 2010
Location: Paris, Ontario
Quote:
Originally Posted by laplace View Post
By VSSA, you mean one of these? Frankly it looks way too simple to be particularly good; has anyone measured a built VSSA to show that its THD+IMD+N is in the same ballpark as Blameless and similar? If true, that would be really awesome.
That is the basis for what I am talking about. It exists in a few different configurations and implementations. To the best of my knowledge those who have built one have all spoken very highly of it. This includes myself; I have built five slightly different variants and not been disappointed by one yet. Here are a few examples of VSSA builds:

PeeCeeBee

FET-hex explendit amplifier

VSSA Through-Hole-PCB build thread

And my own most recent efforts:

VSSA Through-Hole Version by Jason

It is a relatively high speed design and, as an example, has demonstrated near perfect square wave tests in excess of 100kHz. Sorry, for myself I do not posses the equipment to make meaningful measurements of my VSSA builds with respect to THD, IMD and other 'baseline' specifications. All I can say is that no matter what I have built and / or listened to in the place of the VSSA I end up going back to one of the VSSA based designs.

For its relative simplicity it is a really nice sounding circuit in its various incarnations and forms. The VSSA has a very articulate and natural delivery that makes it seem to 'vanish'. There is no 'signature' for this amplifier, it just does exactly what an amplifier should do. A quick example is playing very familiar music and hearing the lyrics so clearly that I realized for my whole life I had misheard the song! I'm not talking about one piece of music either, I have experienced this with different artists and genres. Hearing not just an instrument but even the details of the musician's technique that had not been noticeable before with other amplifiers.

I used to be a specification junkie. I still think there is merit in using specifications to make basic judgements about an unknown. Ultimately however the 'proof is in the pudding' and one has to use the experience of a particular amplifier's performance to decide if it pleases you. It isn't an enormous commitment to try a VSSA out and you may find yourself pleasantly surprised if you give it a try.
__________________
---Jason Kuetemann---
When the student is ready, the master appears.
  Reply With Quote
Old 3rd February 2014, 06:39 AM   #8
laplace is offline laplace  Australia
diyAudio Member
 
Join Date: Jan 2014
Thanks for those links, Jason. I take it that all of your excess boards have been sold? I see in your thread that you're considering a different CCS option - any chance you'll be spinning another batch of boards with that change? I'd also consider having the boards made myself if you're willing to make the design files public.

And where does one buy 2SK1058/2SJ162? Mouser/Farnell know nothing of them but I can buy locally for $20!!! each; are there any good/cheap online stores or trusted eBay vendors? Has anyone tried the Exicon ECX10N20/10P20 devices? Mouser lists a bunch of Fairchild+Infineon 10N20 devices; has anyone tried those? $1 for FQU10N20CTU but I don't see any complementaries there.

If I could get a cheap pair of FETs I'd probably veroboard this to have a play, not that I have any test equipment beyond an analogue CRO to validate the design with. It's not going to happen at $40/pair though.
__________________
Open-Source F/Stop Timer
on flickr
  Reply With Quote
Old 3rd February 2014, 08:42 AM   #9
Banned
 
Join Date: Jun 2013
Location: Melbourne
My suggestion is to stay with something you are, or will be, familiar with, LM3886 amps, get the speakers working properly THEN think about a different amp for the tweeters. My bet is you won't bother because the effort for (any) return may not be worth it.

Abs
ps I don't have Golden Ears, just normal human ones and I also know my senses can be deceived by any number of things.

Last edited by Absconditus; 3rd February 2014 at 08:43 AM. Reason: Spelling error corrected.
  Reply With Quote
Old 3rd February 2014, 09:19 AM   #10
diyAudio Member
 
buzzforb's Avatar
 
Join Date: Oct 2010
Location: Burlington, NC
TSSA 1.7 being being sold by Sonnya in the Vendors section. SITO Audio. Fantastic airy highs. Not harsh at all.
__________________
...Shape the sound , Man!
  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
miniDSP for true active bi-amp system? Jdot miniDSP 0 16th June 2013 05:06 AM
3 way active speaker system + Subwoofer based on Lm 3886 & 4780 kuldeep Chip Amps 13 19th April 2012 09:33 PM
2-way, small FR for mids+highs alspe Multi-Way 14 8th March 2010 11:35 AM
highpass amp strategy for active system? PWatts Pass Labs 1 3rd November 2004 06:43 PM
Active system power amp... Luke123 Multi-Way 1 22nd January 2004 11:00 AM


New To Site? Need Help?

All times are GMT. The time now is 05:10 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