Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Pass Labs This forum is dedicated to Pass Labs discussion.

Amp Camp Amp - ACA
Amp Camp Amp - ACA
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 14th September 2018, 11:49 AM   #5911
kstagger is offline kstagger  United States
diyAudio Member
 
kstagger's Avatar
 
Join Date: Dec 2003
Location: Grand Rapids
The ACA amps - running XLR connected, bridged monoblocks - have now been my main amps for the past few weeks. My tube obsessed friend came over and we played a few cuts. His impressions: it was one of the most neutral SS amps he's ever heard. It doesn't "sound" like solid-state, nor does it sound like tubes. He noted some deficiencies in bass control, which isn't surprising given the bridged connection with 86dB Wharfedale speakers and their 6-ohm impedance. He also like the depth of the soundstage and the detail. He's definitely what you call a subjectivist listener and a tube roller, so take his opinion as you will.

The 90s-era Classe Five preamplifier does a good job driving them - very happy there.

Click the image to open in full size.

Last edited by kstagger; 14th September 2018 at 11:51 AM.
  Reply With Quote
Old 14th September 2018, 01:01 PM   #5912
astromo is online now astromo  Australia
diyAudio Member
 
Join Date: Nov 2017
Location: BFN
Got to head off and snooze a bit but I just thought I'd put in a thank you to M'sieur Pass, the diyA crew, 6L6 and all the forum members who've chipped in with good advice.


Got the first amp built and no smoke. The second will follow. Should be a bit quicker with a 1:1 scale model to work off.


Have just had a quick listen as a single unit, stereo amp and it doesn't disappoint. I should sleep well with those sweet tunes in my head to serenade me to sleep.


Something tells me that this won't be the last build I do but I won't be in a rush for the next round. Time to savour the ACA for a while I'd think..


  Reply With Quote
Old 14th September 2018, 03:35 PM   #5913
oc11 is offline oc11  United States
diyAudio Member
 
Join Date: Jan 2004
Location: Missouri
Hello everybody, I just got my ACA 1.6 and while preparing to start the build took care of reading all the comments in the thread since version 1.6 came out. I am not an expert in anything electronic but love music.

Anyway, there has been some discussion about DAC's and preamps to be used and about finding these with balanced outputs. Reading the comments it looks like ACA prefers an input of 4v RMS to an input of 2v RMS. I looked around and found something that at least from the specs may solve the problem of finding a suitable 4v RMS XLR balanced input directly out of the analog stage of a DAC, no preamp needed. This is the GUNGNIR DAC from Schiit audio. It retails for $849 (multibit upgrade is more). It has 2 balanced XLR outputs and 4 single-ended RCA outputs, an output impedance of 75 ohms. My DAC needs to be upgraded so I plan to look into this option. I have not had any experience with this DAC so far, I am only reporting the specs which look promising for the ACA, at least to me they do.
  Reply With Quote
Old 14th September 2018, 10:57 PM   #5914
oc11 is offline oc11  United States
diyAudio Member
 
Join Date: Jan 2004
Location: Missouri
I have been thinking about the ACA, its case and the very hot heatsinks that are part of it. I have not been building amps, that is for sure, but I have built computers, desktop units primarily (with an occasional redoing of a laptop which is a near nightmare to do), since the 90's and fail to see why anything electrical that gets pretty hot cannot be cooled down to some degree.

So, let me talk about my ideas to make the rig a bit cooler. To increase cooling passively, the case (which is a Mini Dissipante 2U unit 200X300 mm) can be fitted with a pre-drilled bottom and top plates. They are sold at the diyaudio store under "We also recommend, chassis baseplate unit." Of course, I have to confirm that the sizes of the baseplates and top plates I received are the same and the screw holes are in the same place. Once this is done, the bottom and top plates that come with your case can be replaced with the pre-drilled ones. These are, I believe, pre-tapped to accept screws in the holes. All you really have to do is to decide which holes you want to keep as pre-tapped holes, and basically drill out the rest of the screw threads in the other holes to enlarge them and allow free air circulation. The legs of the unit can be replaced with taller legs to allow for freer passive air flow by convection from the bottom. Assuming you can also replace the top plate with a pre-drilled one, you can significantly increase the level of air circulation within the unit in a purely passive manner.

But why stay there, you can buy computer case fans which are silent and install them on the top of the units to extract hot air from them. A number of these fans come with USB connectors for external use. So all you need is to choose your fans for airflow, size and silent operation, install them and hook them up to an external USB hub that connects to AC. Make sure the top plates' pre-drilled holes left unused are also enlarged to facilitate the air flow. I honestly have no idea how much heat can be dissipated that way but it may be significant.

If you go passive the air convection through the units happens without additional noise. If you use fans you can expect background noise in the 28 dB level which may or may not be acceptable to you personally. Again this is nothing that I have already done with an amplifier but I have done it many times with computers. I think this is entirely feasible to do with the pre-drilled plates. The plates are 3 mm aluminum so drilling them is not impossible to do at home.

Hope you like this small contribution to possible amp cooling solutions from the PC world.
  Reply With Quote
Old 14th September 2018, 11:04 PM   #5915
oc11 is offline oc11  United States
diyAudio Member
 
Join Date: Jan 2004
Location: Missouri
My apologies, I did not realize the top plates are perforated already. This is both good and bad, good because you do not need to get the pre-drilled bottom plate and place it on the top after enlarging the holes. Bad because you have to tap the holes to take the fan screws in the appropriate places.
  Reply With Quote
Old 15th September 2018, 12:32 AM   #5916
rekterx is offline rekterx  United States
diyAudio Member
 
Join Date: Jan 2014
Location: Near Philly
Hello ... complete noob here .... just completed kit and ...... Why am I getting a 36v reading on one side that I don't seem to be able to adjust down while the other side I could dial in at 12 volts?
  Reply With Quote
Old 15th September 2018, 12:38 AM   #5917
adason is offline adason  United States
diyAudio Member
 
adason's Avatar
 
Join Date: Nov 2004
Location: Maryland
Power supply is 24 volts. How did you manage to convert it to 36? You must be making electricity...
  Reply With Quote
Old 15th September 2018, 12:54 AM   #5918
rekterx is offline rekterx  United States
diyAudio Member
 
Join Date: Jan 2014
Location: Near Philly
Quote:
Originally Posted by adason View Post
Power supply is 24 volts. How did you manage to convert it to 36? You must be making electricity...
I wondered the same thing. I have used two different multimeters.
  Reply With Quote
Old 15th September 2018, 01:20 AM   #5919
rekterx is offline rekterx  United States
diyAudio Member
 
Join Date: Jan 2014
Location: Near Philly
Mystery solved! I grabbed the wrong power supply .... a 36 volt supply that I use on a tda4798e amp. Oops!

And I didn't have it on for very long. Do you think I did any damage?

Last edited by rekterx; 15th September 2018 at 01:32 AM.
  Reply With Quote
Old 15th September 2018, 01:50 AM   #5920
adason is offline adason  United States
diyAudio Member
 
adason's Avatar
 
Join Date: Nov 2004
Location: Maryland
May be you killed the jfet.
When you now connect 24 volt supply, can you bias it to 12 volts?
If you can, you are in luck. If not, you exceeded volts on little jfet.
  Reply With Quote

Reply


Amp Camp Amp - ACAHide 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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Amp Camp Amp #1 Nelson Pass diyAudio.com Articles 54 8th May 2018 03:13 AM
Amp Camp! Jason Site Announcements 2 30th June 2012 02:57 PM
Best D camp config for Tweeter amp Zero One Class D 0 24th February 2010 04:57 AM
better the Pass camp? rick57 Tubes / Valves 6 26th March 2005 06:04 AM


New To Site? Need Help?

All times are GMT. The time now is 09:04 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki