DHL had quite a hard time figuring out where Austria is
DHL eCommerce (nothing to do with the real DHL apart the logo) is the worst postal (dis)service on earth
This time shipping from diyAudio Store went unbelievably fine (in august was instead a nightmare) but a pair of Sennheiser headphones from Massdrop, in these very same days, simply went lost
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Yes, if you want to run it as a 'Bridged' monoblock, RCA input. Just use the 39.2K resistor from the kit in place of the two 68.1K shown.
(The reference at post #6522 is for 'Parallel' monoblock mode.)
Yes, no need for it at all.
Alan
ACA V1.6 Heat Differential
Hi,
I have my two ACA running in bridged monoblock mode and they sound great. The heat output is noticeably hotter on one of the amps than the other. I can put my hands on one of the amp’s heat sinks and keep it there indefinitely. With the other, I can put my hands on the heat sinks but only for a handful of seconds before I need to remove them.
I ran some pink noise and used an app on my iPhone to check the decibel levels coming out from each speaker and they pretty much line up. I was going to pull them out to check the potentiometer setting to make sure they are still at 12V, but when I made the initial adjustments, I let them warm up for a couple hours, then made the adjustments, then let them sit a while, and then checked them again - all pretty close (within 2 hundredths of 12V).
I did accidentally install the pcb’s differently on each amp. On one of the amps I installed the PCB’s so they are essentially a mirror image of each other (with the potentiamoters both “up” towards the top of the amp). The other amp were installed with one board where the potentiometer is at the top of the amp, and the other board where the potentiometer is at the bottom.
Thoughts? Is this an issue? Should I pull everything apart on one of the amps to switch around the PCB/heat sink?
Thanks. Happy Thanksgiving.
Jim.
Hi,
I have my two ACA running in bridged monoblock mode and they sound great. The heat output is noticeably hotter on one of the amps than the other. I can put my hands on one of the amp’s heat sinks and keep it there indefinitely. With the other, I can put my hands on the heat sinks but only for a handful of seconds before I need to remove them.
I ran some pink noise and used an app on my iPhone to check the decibel levels coming out from each speaker and they pretty much line up. I was going to pull them out to check the potentiometer setting to make sure they are still at 12V, but when I made the initial adjustments, I let them warm up for a couple hours, then made the adjustments, then let them sit a while, and then checked them again - all pretty close (within 2 hundredths of 12V).
I did accidentally install the pcb’s differently on each amp. On one of the amps I installed the PCB’s so they are essentially a mirror image of each other (with the potentiamoters both “up” towards the top of the amp). The other amp were installed with one board where the potentiometer is at the top of the amp, and the other board where the potentiometer is at the bottom.
Thoughts? Is this an issue? Should I pull everything apart on one of the amps to switch around the PCB/heat sink?
Thanks. Happy Thanksgiving.
Jim.
If you have a way to measure temps, could you measure the actual temp of the MOSFETs? This will require an instrument, can't be done by hand.
Other than Mooly's suggestion which will speak about actual current... checking the temp of the MOSFET vs the temp of the Heatsink could provide info on the mechanical coupling of the MOSFETs to the Heatsink. Maybe one of them (the one running cooler?) is not absorbing as much heat as it could from the MOSFET and therefore the component is running much hotter?
Good luck!
Rafa.
Other than Mooly's suggestion which will speak about actual current... checking the temp of the MOSFET vs the temp of the Heatsink could provide info on the mechanical coupling of the MOSFETs to the Heatsink. Maybe one of them (the one running cooler?) is not absorbing as much heat as it could from the MOSFET and therefore the component is running much hotter?
Good luck!
Rafa.
ACA Heat Differential
Hi,
Thanks for the responses. I measured across R1. The hot amp(s) measured 0.311V. The cool amp(s) measured 0.319V.
I double checked the potentiameters and they are all sitting very close to 12V (couple hundredths in either direction).
Not sure how I can measure the temp other than using a meat thermometer.
Regarding the flip flop placement of the PCB’s. The cool amp is the one where they are mirrored (installed incorrectly according to the build guide - potentiometers both “up”).
Thanks again.
Jim.
Hi,
Thanks for the responses. I measured across R1. The hot amp(s) measured 0.311V. The cool amp(s) measured 0.319V.
I double checked the potentiameters and they are all sitting very close to 12V (couple hundredths in either direction).
Not sure how I can measure the temp other than using a meat thermometer.
Regarding the flip flop placement of the PCB’s. The cool amp is the one where they are mirrored (installed incorrectly according to the build guide - potentiometers both “up”).
Thanks again.
Jim.
That sounds a good result. Assuming the resistors are the correct values we can safely say that any perceived temperature differences must come down to physical differences in the builds and/or location of the amps.
The measurement defines the current precisely at 1.36 amps which is bang on the money as to the range it should be within.
The measurement defines the current precisely at 1.36 amps which is bang on the money as to the range it should be within.
ACA V1.6 Temperature Differential
Yep. Forgot to mention that I checked R1-R4 and they are all correct. I also measured all of the components before stuffing the boards and they were correct.
Since they sound great, I guess I’ll just chalk it up to the ghost in the machine. It is pretty weird though. It is pretty noticeably different temps. My neighbor came over and I asked him to put his hands on both sides of each amp and he noticed it as well (without me telling him anything).
Anyways, thanks for the replies and input.
Jim.
Yep. Forgot to mention that I checked R1-R4 and they are all correct. I also measured all of the components before stuffing the boards and they were correct.
Since they sound great, I guess I’ll just chalk it up to the ghost in the machine. It is pretty weird though. It is pretty noticeably different temps. My neighbor came over and I asked him to put his hands on both sides of each amp and he noticed it as well (without me telling him anything).
Anyways, thanks for the replies and input.
Jim.
One thing I didn't mention was to check the measured power supply voltage.
Assuming both are running on 24 volts then the numbers give a dissipation of 1.36*24 which is 32 watts per channel. Any imbalance in the 12 volt mid-point setting will not alter the overall dissipation, it would only alter the split between the two power transistors.
Assuming both are running on 24 volts then the numbers give a dissipation of 1.36*24 which is 32 watts per channel. Any imbalance in the 12 volt mid-point setting will not alter the overall dissipation, it would only alter the split between the two power transistors.
Speaker choice question
I’ve been wanting to build an amp camp amp for a while now but want to make sure it will match well with my current speakers.
I’ve a pair of Tannoy proto-j speakers. Their specs are on one of the last pages of their manual, here:
https://www.fullcompass.com/common/files/2716-ProtoJManual.pdf
I have no idea what “efficient “ and “easy load” is supposed to mean and that’s how the amp camp page words their description for speaker recommendations.
What are they meaning and do these proto j’s fit the bill?
Sincerely,
Hawley
I’ve been wanting to build an amp camp amp for a while now but want to make sure it will match well with my current speakers.
I’ve a pair of Tannoy proto-j speakers. Their specs are on one of the last pages of their manual, here:
https://www.fullcompass.com/common/files/2716-ProtoJManual.pdf
I have no idea what “efficient “ and “easy load” is supposed to mean and that’s how the amp camp page words their description for speaker recommendations.
What are they meaning and do these proto j’s fit the bill?
Sincerely,
Hawley
6 Ohms and 90dBs (which with the asterisk seems like 87), you have fairly ‘normal’ speakers. That is what most of us are working with (mine are 4ohm 87dBs).
You would love the ACÁ if you can put a small pre with some gain in front of it. Without it, you will like it, but it could be a bit thin or less loud depending on your listening area.
With two ACAs in one of the monoblock configurations, you would have enough power even without the pre.
So if you have a pre, the build one. If you don’t, you may be better of building two. Or get an inexpensive pre to get a glimpse of what if may sound like.
At any rate, you would love the experience, and, for the price, there are few amps that can come close to this sound IMHO.
Hope this helps,
Rafa.
You would love the ACÁ if you can put a small pre with some gain in front of it. Without it, you will like it, but it could be a bit thin or less loud depending on your listening area.
With two ACAs in one of the monoblock configurations, you would have enough power even without the pre.
So if you have a pre, the build one. If you don’t, you may be better of building two. Or get an inexpensive pre to get a glimpse of what if may sound like.
At any rate, you would love the experience, and, for the price, there are few amps that can come close to this sound IMHO.
Hope this helps,
Rafa.
While I agree, I have a problem with this advice. It assumes that A: you can listed to the item being discussed, or B: you can afford to buy the item even if you'd not like it in the long run.
So, numbers are a good start to determine if you should venture into a particular project.
But Hawleyw, as you can read, most of us are using setups very similar to yours, some of us actually have harder to drive speakers (mine for instance). So I really don't think that you should worry about the matching of your speakers. They will work just fine!
Hi Hawley,
A lot depends on the size of your listening space and your volume preference.
If you have never used a low power amp with your speakers, may I suggest
you try the test outlined in this thread:
A Test. How much Voltage (power) do your speakers need?
This will give you an idea of how much power you might need based on your
listening habits. And sometimes this value is lower than you may have expected.
Cheers,
Dennis
A lot depends on the size of your listening space and your volume preference.
If you have never used a low power amp with your speakers, may I suggest
you try the test outlined in this thread:
A Test. How much Voltage (power) do your speakers need?
This will give you an idea of how much power you might need based on your
listening habits. And sometimes this value is lower than you may have expected.
Cheers,
Dennis