She didn't realise what she was letting herself in for, once done and running, I'll introduce her to this forum.
She will be a fully fledged member having built the ACA.
She is a keeper alright.
She will be a fully fledged member having built the ACA.
She is a keeper alright.
Thanks for the feedback. I am thinking of creating a simple low $ setup using my existing work PC to a Schitt Modi DAC to a pair of ACA's connected to SVS sub and the wharfe 10.1s. Any opinions?
So I’ve completed the amp works well but sounds harsh and sound stage compressed in the middle, what is the experience on break in time?
DIY pre-amps for ACA
Just thought I’d chime in with a thumbs up for Both the WHAMMY and Starving Student headphone amps as great DIY options for ACA and other amps as well. I’ve used both and they sound great.
To my ears, Starving Student provides more gain and gives a touch of tube warmth, but is not as dead silent as WHAMMY and gives a slightly less detailed sound.
Just thought I’d chime in with a thumbs up for Both the WHAMMY and Starving Student headphone amps as great DIY options for ACA and other amps as well. I’ve used both and they sound great.
To my ears, Starving Student provides more gain and gives a touch of tube warmth, but is not as dead silent as WHAMMY and gives a slightly less detailed sound.
Source is a PS audio DAC, speakers are 4pi, SPL maybe 88. Source prior to DAC is Apply laptop where I ripped CDs in Apple Lossless, and it is connected via fiber to the DAC. It has all sounded wonderful before.
That’s weird. I’ve never heard 4Pi’s sound compressed. Shouty depending on the amp, but never compressed.
When you say 4PI speakers do you mean the Pi Speakers model designed by Wayne Parham? I have a set of 3 Pi that I built with the upgraded drivers and crossovers built with better parts. The ACA drove them easily to quite loud levels. The 4PI is listed at around 97db efficiency and an 8 ohm load. Should work well with ACA. As said above, check the phasing, both inside the amp and at the speaker connections.
I'm running a single ACA into a pair of 2 Pi Towers in a medium sized room without issue. The 2 Pi's are about 95db sensitive and an easy load. The combo has more than enough power for jazz and reasonable enough for more lively genres as my mood strikes. If you like rock at concert levels you'd might need more oomph from a more powerful amp, but even up to moderate-to-loud levels it's a fine combo.
As for break in of the ACA, it sounded better over time. By 10 hours it was improving and by 30 the treble was a lot smoother. There were probably improvements after that but far less pronounced.
For some reason I recall the Whammy break in period better, probably because it was the last thing built. It was kind of coarse and gritty for a bit then smoothed out over time. You could hear the changes well into the 40 or 50 hour point. Now there isn't a coarse or gritty thing about it.
Thanks for the comments. Yes, 4pi as in Wayne's design but upgraded to the B&C driver on top. I've always used them with tube amps ranging from 8 watt 300Bs to current pair of 60w KT88's (all built by me). Late last night it was sounding a bit smoother, or maybe it was the scotch kicking in... Initially it seemed like some instruments were muted while others stood out, not even in response. But I'll give it a few more hours and see how we do.
It'll probably be mostly there by 50 or 75 hours. It might change a bit after that but not as much as it does at first.
It's also a much clearer presentation than many tube amps so there may be some adjusting needed on your part. It's sonics probably fall somewhere between tube amps and class d amps. There's enough of a difference in the amps in my place that the speakers get repositioned depending on which amp is connected.
Please keep us in the loop. I hope to get a pair of 4 pi's in the next few months and am curious as to how well they mate with the ACA. Some folks claim they need a lot of watts to open up but Wayne demos them at the Lone Star show with a 10 watt tube amp. They kick pretty well with his amp.
I've used the 4pi with a Single Ended 45 (3 watts) and it does well but with my 60w KT88 monoblocks - outstanding. The little ACA is doing very well in the kick department, by the way. I was playing some Ray Brown Trio stuff last night and the upright bass was outstanding.
Question about the power supply upgrade: Before I drop $100 I'd appreciate any impressions from folks who have done the upgrade with the V1.0 ACA kit (that came as monoblocks). Are the Meanwells worth it in your opinion? I'm currently feeling torn between the PS upgrade and saving that money for my eventual Aleph J project. If there's an improvement in sound with the Meanwells, then I'd probably go for the upgrade. If it's just more power, then I'll hold off. Any input would be appreciated!
In my opinion it is wise to remember that the raison d'être of ACA is: introduction to amplifiers you build yourself, through the simplest, smallest, cutest possible class-A amp.
If you've built and listened to an ACA then, in my opinion, you've been introduced. Now it's time to meet some more sophisticated amps whose ambitions extend beyond "easy to build".
I haven't said it enough so here goes, one more time: in my opinion.
If you've built and listened to an ACA then, in my opinion, you've been introduced. Now it's time to meet some more sophisticated amps whose ambitions extend beyond "easy to build".
I haven't said it enough so here goes, one more time: in my opinion.
Well that settles it! Thanks for the input, Mark and Jim. Over to the Aleph J build thread I go... 🙂
i did two versions of the bridged AmpCamAmps, a fully balanced one, and single ended front end using a 6BC4 tube gain stage, i used 47k/10k for the gain resistors to lower the gain a bit...
the fully balanced version needed a SY inspired 7n7/6rhh8 preamps with balanced outputs..
the fully balanced version needed a SY inspired 7n7/6rhh8 preamps with balanced outputs..
Attachments
