Hi @broccoli_rabe. It isn't the Forte's that are wired one way or the other, but the Pass ACA amplifier. The latest version has the option of output in stereo, parallel mono, or bridged mono.
Please see steps 14, 15, 16, 17.
https://guides.diyaudio.com/Guide/Amp+Camp+Amp+V1.8+Change+Information/10?lang=en
https://guides.diyaudio.com/Guide/Amp+Camp+Amp+V1.8+Change+Information/10?lang=en
It seems as the consensus is the aca being wired in parallel. Is there a particular reason why? Does it reduce resistance or increase power output? Sorry for the entry level questions, just trying to get a better grasp of the concept.
Both channels of the amp are used to power one speaker. And then you need a 2nd ACA for the other speaker.
Power is increased because of monoblock operation.
Power is increased because of monoblock operation.
Entry level questions are good.
The stereo output power of the latest model ACA is 8 wpc. In either bridged or parallel mono mode, it jumps to 15 wpc. With the Forte, the ACA is spectacular!
The stereo output power of the latest model ACA is 8 wpc. In either bridged or parallel mono mode, it jumps to 15 wpc. With the Forte, the ACA is spectacular!
Thank you guys for the answers to my questions. I do like my fortes. I’ve been using them with a quality NAD set up for a few years but I’ve been wanting to take advantage of their high sensitivity and try something a little more low powered. The aca seems like a great option, and the support on this forum seems unmatched!
The second ACA is up and running and I've been driving my wife a little crazy today trying out all the options. Started out just comparing the new amp to the old one to make sure they match well. No problems. Tried bi-amp, bridged mono and parallel mono. Noticed nice improvements in detail and sound stage, and tighter bass with all, but have to agree that the parallel mono is exceptional. What really blows me away is how all of the improvements are present at lower volumes.
Follow on question... Is there value in checking the output of the two amps to be sure they match? If so, how and what adjustments can be made if needed? My thought would be to test the voltage at the speaker terminals then adjust the internal voltage trim pots if needed, but that's just a guess. All probably unnecessary, but I ask to learn. 🙂
The midpoint voltage has no effect on gain so no need to try and set them identically.
As long as the component values are correct both will output similar audio levels and the high output impedance means there are no worries over the amps 'fighting' each other when in parallel even if there were very slight gain differences due to resistor tolerance etc. The midpoint setting has no effect on that though.
As long as the component values are correct both will output similar audio levels and the high output impedance means there are no worries over the amps 'fighting' each other when in parallel even if there were very slight gain differences due to resistor tolerance etc. The midpoint setting has no effect on that though.
It's not the cap actually, its mainly a consequence of the very low (comparatively speaking) open loop gain of the amp but also remember that aspect is also part of what makes it what it is and why it sounds as it does.
thx mooly
i actually changed my first p ACA . i have the feeling that it gets too hot (1,9A bias) in the small case and therefore i changed to a "normal" bias setup.
means new IRFP044. change the BF245 (its crap) to very nice J117 Toshiba. change the RG cable to mogami W2944. bias is about 1,4A
sound is very good for single ended in my small case.
chris
i actually changed my first p ACA . i have the feeling that it gets too hot (1,9A bias) in the small case and therefore i changed to a "normal" bias setup.
means new IRFP044. change the BF245 (its crap) to very nice J117 Toshiba. change the RG cable to mogami W2944. bias is about 1,4A
sound is very good for single ended in my small case.
chris
If you decide to delete the dot for four wire junctions, then you MUST add a jumper for wires that cross but do not connect.
Personally, I have always used both the dot and the jumper. Why be ambiguous?
Friends, please forgive me for not reading all 607 pages (12,000+ posts!) in this thread, but I have a question for which the answer is surely buried somewhere,
What is the recommended Idss class for the LSK170 JFET at the input?
tia,
Jan
What is the recommended Idss class for the LSK170 JFET at the input?
tia,
Jan
