Please see my posts 2779 and 2780: http://www.diyaudio.com/forums/pass-labs/215392-amp-camp-amp-aca-278.html#post4779516
The change from a 19V to 24V DC rail should not tax any other components (caps and resistors). 24V switchers at 3-4A should be fine, remember the idling current is about 1.4A since it's a Class A SE circuit (not push pull). So the supply should be able to deliver a little more than 2A of current short term per Pass. 24V will provide slightly more power, and it's a bit easier to find a 24V switcher IMHO. Remember each channel should preferably have its own switcher supply.
Sonic differences? You tell me!
I hope the above helps some folks. Enjoy your builds.
Best,
Anand.
The change from a 19V to 24V DC rail should not tax any other components (caps and resistors). 24V switchers at 3-4A should be fine, remember the idling current is about 1.4A since it's a Class A SE circuit (not push pull). So the supply should be able to deliver a little more than 2A of current short term per Pass. 24V will provide slightly more power, and it's a bit easier to find a 24V switcher IMHO. Remember each channel should preferably have its own switcher supply.
Sonic differences? You tell me!
I hope the above helps some folks. Enjoy your builds.
Best,
Anand.
Thanks Anand. That is reassuring as 24v is more common and it seems difficult to find a linear PS at 24v that is over 4A without getting quite expensive. I guess a less expensive 24v switcher would give some benefit without the added cost but, if I'm going to go that route, it seems like going linear in the hopes of less noise would make sense.
I was hoping to get a sense if the increased voltage change the sound character (other that adding power, gain, or headroom/dynamics) as a 19v linear would then be preferable. Probably too subjective of a question though.
Yes, and please do understand that +24V EBay switchers are a far cry from the SMPS-86 from Neurochrome Audio. You can use the SMPS-86 to get just +24V (instead of +/- 24VDC) by using (2) 12V modules (IRM-60-12 modules), and connecting the negative output to ground. You would then have a +24VDC @5A!
You can contact tomchr for details. I'm just a happy customer, so take my recommendations with a dash of sea salt
Best,
Anand.
You can contact tomchr for details. I'm just a happy customer, so take my recommendations with a dash of sea salt
Best,
Anand.
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Actually I believe that Nelson used the 19v. PSU's because they are a very very common PSU for Laptops, so lots are available. Also quite available as surplus items dirt cheap! In my experience searching for supplies to use with our ACA kits, the 19v. tend to be much cheaper. So there's no reason to assume 19v is better, the 24v is probably at least as good and more powerful, and some here say sounds better too!
Nelson specified "at least 2A" for the 19v PSU in his article, which would be good reading for you. I found a great deal on 19v, 4.7A supplies so have used them in the kit as I thought that being rated at much more amperage, they would be less stressed, and that possibly we might have a kit option to have just one power supply. That never happened as the additional cost of 2 was not that significant, and having "monoblocks", each with a separate supply seemed more High End, and probably is in fact better.
So yeah, as was recently posted, 3-4 Amps is just fine at 24V. Just change the pot as mentioned, to about 12.5v.
It is the logical upgrade for your, and WILL put out more hjeat so the bigger chassis makes sense.
Nelson specified "at least 2A" for the 19v PSU in his article, which would be good reading for you. I found a great deal on 19v, 4.7A supplies so have used them in the kit as I thought that being rated at much more amperage, they would be less stressed, and that possibly we might have a kit option to have just one power supply. That never happened as the additional cost of 2 was not that significant, and having "monoblocks", each with a separate supply seemed more High End, and probably is in fact better.
So yeah, as was recently posted, 3-4 Amps is just fine at 24V. Just change the pot as mentioned, to about 12.5v.
It is the logical upgrade for your, and WILL put out more hjeat so the bigger chassis makes sense.
when i changed to 24v set up I didnt want to spend a massive amount of money so i went for switching supplies i have efficient speakers and i cant hear any noise from them even with my ear against the cone. I dont know what differences a better quality supply such as the SMPS-86 ($200!) would bring as ive no experience Im sure figures reading scope might be better but I spent only £26 on two supplies from amazon KeerSen DC 24V 8A 200W Switching Power Supply Regulated Transformer w/ Short Circuit and Over Current Protection (24V8A) ( not in stock anymore it seems as link does not work.Im very happy with the perceived increase in enjoyment in listening its just got a bit more ACA about it. It does run hot so ive added a fan underneath and the temperature of the heatsinks seems fine.
My experience with listening is that we can have a system that sounds great but then we get a hankering for some change just that. This mod did it for me I can go through my music and feel Im listening to something new, so Ill keep tinkering next is to try just two twisted cat 5 speaker cables instead of the multi twisted which are still in the system from using less efficient speakers and alter the, dare i mention it ground side loops! ha ha now thats strange!!
My experience with listening is that we can have a system that sounds great but then we get a hankering for some change just that. This mod did it for me I can go through my music and feel Im listening to something new, so Ill keep tinkering next is to try just two twisted cat 5 speaker cables instead of the multi twisted which are still in the system from using less efficient speakers and alter the, dare i mention it ground side loops! ha ha now thats strange!!
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Hi Ananda I know there is a part of me that thinks, if this sounds good now what would it sound like with decent power supplies, but I also know id have to find the time to build them!!!!! so ill just have to live with it as is . If you do build those, when they are up and running defiantly looking forward to hearing about them Thanks
I picked up these for my new ACA - RSP-500-24 http://www.meanwell.com/mw_search/RSP-500/RSP-500-spec.pdf
Pretty capable and 500w so they should be barely ticking over with 2 ACA channels running....
Pretty capable and 500w so they should be barely ticking over with 2 ACA channels running....
Thanks for chiming in Variac. I did read Nelson's article, though didn't retain the 19v/2A spec. Sounds like it's the way to go then. Under 4A and there are some that are reasonable. And I agree about separate power supplies for monoblocs. Sharing a supply would tend to run counter to the reason for having monos!
My kit arrived today, so I'm working on setting up a workspace and will begin shortly. I really should order a better quality soldering iron first though.
I may have to start with a fan if I do upgrade to 24v. If it looks like that PS will be permanent, I will look at a bigger chassis. Do you have a recommendation for a particular chassis from your store that would provide the proper size and heatsinks or are we looking at the First Watt chassis? And I assume I would be mounting both amps in a single chassis in this case. I think they call that "dual mono".
My kit arrived today, so I'm working on setting up a workspace and will begin shortly. I really should order a better quality soldering iron first though.
I may have to start with a fan if I do upgrade to 24v. If it looks like that PS will be permanent, I will look at a bigger chassis. Do you have a recommendation for a particular chassis from your store that would provide the proper size and heatsinks or are we looking at the First Watt chassis? And I assume I would be mounting both amps in a single chassis in this case. I think they call that "dual mono".
Nice way to mix it up. You just have to make it and see how it sounds. The 2SK170 is legendary for ultralow noise so not sure how the IRF610, a power MOSFET will hold up. I know a 2sk170 can drive a IRF610 very nicely (F5 head amp) so nmaybe a cool mod would be a 2sk170 driving a IRF610 so that we can get a higher gain amp like traditional 26dB SS amp? I see you are using BD139. According to F5 build guide, BC550/560 are good substitutes for ZTX450/550.
http://www.diyaudio.com/media/build-guides/diyaudio-f5-build-guide.pdf
You can try the Cresent smps they are good and would be even cheaper than the one you mentioned. I am uaing them with firsr one with +/- 55v output, but it can easily do +/-24 the output voltage is cinfigurable on order.
Sent from my ONE A2003 using Tapatalk
Would you like me to come visit you again with a brace of meanwell PS? It's been a while
Yes it would be great ill see how thinks are in a couple of weeks !!!
M
Beautiful work. You plan on running at 30v? Hot!!!
Yes, my wife asked me a heater, so I'll ride one.
