Hi. Building my ACA. Soldering went easy (I'm quite confident in it already), but I think I was a bit over zealous when tightening the mosfets to the heat sink on one channel. I see the keratherm is a bit squashed under the mosfet and I worry if it would not shortcircuit to ground (picture attached). I tried to measure the resistance between the chassis and all the pins and all the pins measure about 1K (the same as on the other channel that is tightened perfectly). So, am I ok? Or this resistance tells nothing? What would happen if the mosfet does shorts on the chassis (or start shorting after some time of use)?
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Probably OK and if there was a short it would read as such.
The recommended tightening torque of these transistors is not much and assumes a perfectly flat surface of course. It is around 1.1 N m or 0.8 ft/lbs. So not very much. If you think you have overtightened them then on balance I think I would leave them rather than slacken them.
If the top FET shorted to chassis then the supply would be shorted, if the lower FET shorted then the current draw would remain the same but the top FET would dissipate twice the power because it would see the full rail voltage.
The recommended tightening torque of these transistors is not much and assumes a perfectly flat surface of course. It is around 1.1 N m or 0.8 ft/lbs. So not very much. If you think you have overtightened them then on balance I think I would leave them rather than slacken them.
If the top FET shorted to chassis then the supply would be shorted, if the lower FET shorted then the current draw would remain the same but the top FET would dissipate twice the power because it would see the full rail voltage.
modes of operation 1.8 kit
I am building 2 complete amp camp kits, my intention was to have 1 amp for the left channel speaker and 1 amp for the right channel speaker is this referred to as bridge mono? or is this something different
my intention is to connect the left pre amp output to the left input of the left amp camp and have 1 left speaker connected to it
and the other side or right channel output from my pre amp would be connected to the right side input of the amp and have the right side speaker connected to that
confused
I am building 2 complete amp camp kits, my intention was to have 1 amp for the left channel speaker and 1 amp for the right channel speaker is this referred to as bridge mono? or is this something different
my intention is to connect the left pre amp output to the left input of the left amp camp and have 1 left speaker connected to it
and the other side or right channel output from my pre amp would be connected to the right side input of the amp and have the right side speaker connected to that
confused
Yes, that's what I thought too - better to leave it as is now when it does not show shortcircuit with the multimeter.
Thanks. I will make a comment in the build guide about that to help saving others from that mistake.
-Alvis
I agree - don't worry about that; it looks installed properly. In the worst case you won't thermally conduct perfectly but you'll get conduction and thats good enough in this project. The worst thing you can do is over-tighten the MOSFET and crack the case of the transistor because its probably ruined at that point. I am sure there is a torque spec, but generally if its snug down and looks like as you said, the keratherm is a bit squashed against the heat sink, that is good. If it can be slid back-forth, you aren't tight-enough yet. Creep up to it.
I also recommend using both the washer AND the locking washer. It keeps things connected solidly, even after things heat up or vibrate over time. It looks like the current ACA 1.8 kit comes with this part but I can't tell from your figure if you used it.
--Tom
Your intention is correct, except your input and output plan is most likely wrong. If you look through this thread, there should be a link to the wiring guide somewhere. (Edit, check out this page: Amp Camp Amp V1.8 Build Guide - diyAudio Guides ). Unfortunately I am not sure if you should attach the preamp inputs and speaker outputs as shown in the 1.6 build guide linked from the above page, or if there s a different way now. Step 55 on this page shows how to attach the preamp and speakers for bridged monoblock: Amp Camp Amp V1.6 Build Guide - diyAudio Guides
Depending on the impedance of the speakers you are driving, you may want to set the amps up as parallel mono instead of bridged mono. Generally 8 ohm and above speakers would use bridged mono (more voltage), while 4 ohm speakers would use parallel mono (more current). I have a pair of speakers that are advertised as 8 ohm (Klipsch Forte) but they sound better using parallel mono configuration. If bridged mono sounds a bit loose in the bass, try parallel mono.
Alan
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Yes 'bridge mono' RCA input.
Correct.
No wrong. You use exactly the same layout for both channels. So in bridge mode with RCA input, Both amps use the White (left if you like) input socket. And both amps have the same speaker output connections. Follow the picture in step 55 of the build guide for both. There is no change here from V1.6 to V1.8. See enclosed.
The reason is, in bridge RCA mode, the input signal to the Red channel comes from the White side output via the 39K resistor. Both amps are built the same so do not 'mirror'.
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Good plan! It is very common to do this with with your ACA 1.6 design.
You could also wire your 1.6 amps exactly like a 1.8 Amp. They are the same thing really, just that the 1.8 is wired a bit differently and requires a different rear switch. And most useful, there is a rear panel in the kit with text explaining the various monoblock hookups. However a 1.6 with standard wiring will also work fine to use as a “monoblock” , meaning one chassis per channel. You always have the choice of a bridged monoblock or a parallel monoblock, (or even a balanced monoblock with a balanced preamp), it’s just that the 1.6 requires a few more external cables to do the hook up. Nothing inside the 1.6 needs to be changed.
You could also wire your 1.6 amps exactly like a 1.8 Amp. They are the same thing really, just that the 1.8 is wired a bit differently and requires a different rear switch. And most useful, there is a rear panel in the kit with text explaining the various monoblock hookups. However a 1.6 with standard wiring will also work fine to use as a “monoblock” , meaning one chassis per channel. You always have the choice of a bridged monoblock or a parallel monoblock, (or even a balanced monoblock with a balanced preamp), it’s just that the 1.6 requires a few more external cables to do the hook up. Nothing inside the 1.6 needs to be changed.
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The saga ends! Put the amp camp back together (top and bottom) turned in on left channel was out! Pulled the covers off and pin 2 on Q1 read MILLI volts! Dang nabbit!!! Went upstairs, poured a glass or four of wine and cried myself to sleep... woke up at 6:30am, made an extra strong cup of coffee, pulled a pcb out of my spare kit, an hour or so later had my first listen!!
Sounds good, have to put the amp on real speakers to really hear it and thats where you folks come in. I know some here have the Elsinores, and wonder if this puppy can make them sing...
Elsinore's are efficient but are designed to be current driven...
Have the Elacs i could temporarily hook up, but due to space wife constraints would have to wait until i have the living room to myself lol...
Now, to decide what to do with spare the troubled channel ��
Sounds good, have to put the amp on real speakers to really hear it and thats where you folks come in. I know some here have the Elsinores, and wonder if this puppy can make them sing...
Elsinore's are efficient but are designed to be current driven...
Have the Elacs i could temporarily hook up, but due to space wife constraints would have to wait until i have the living room to myself lol...
Now, to decide what to do with spare the troubled channel ��
amp camp build 1.8
i am just finishing off the amp camp 1.8 build and i have 1 question, in the kit there are 2 blue LED's and i see that these are for power indicators on the front panel, however i also have 2 Red LED's but i must be missing something because i cant see in the desing notes or diagram of where these are installed.
any help would be appreciated
Dan
i am just finishing off the amp camp 1.8 build and i have 1 question, in the kit there are 2 blue LED's and i see that these are for power indicators on the front panel, however i also have 2 Red LED's but i must be missing something because i cant see in the desing notes or diagram of where these are installed.
any help would be appreciated
Dan