My ACAs are hooked up to Zaph Audio ZA 5.2 for normal listening. They are 83-84db efficient on their best day. I mostly listen to them straight out of a computer headphone jack, phone, or iPad.
With the ACA in bridged mono (RCA) they get more than loud enough for my room and musical tastes, even without a preamp. (Remember that there is an increase in gain with bridging.)
Using the ACA with the same speakers as a single stereo amp, it’s still plenty of gain and power for normal listening, though at times when wanting to turn it way up if the music allows, I find the phone/computer source running out of gain. Adding a preamp alleviates that, but i rarely find it truly necessary.
Jason and I were playing with mono (XLR) ACA feeding my Sony ES SS-M7 speakers when he visited, which are 3-way 6ohm and 86db. They were driven comfortably to levels too high for continued listening without hearing damage. (Being fed from a DAC/Preamp with lots and lots of output voltage.)
Moral of story - ACA amp can drive most, if not all speakers. If you don't have enough volume a preamp can be useful to add system gain.
With the ACA in bridged mono (RCA) they get more than loud enough for my room and musical tastes, even without a preamp. (Remember that there is an increase in gain with bridging.)
Using the ACA with the same speakers as a single stereo amp, it’s still plenty of gain and power for normal listening, though at times when wanting to turn it way up if the music allows, I find the phone/computer source running out of gain. Adding a preamp alleviates that, but i rarely find it truly necessary.
Jason and I were playing with mono (XLR) ACA feeding my Sony ES SS-M7 speakers when he visited, which are 3-way 6ohm and 86db. They were driven comfortably to levels too high for continued listening without hearing damage. (Being fed from a DAC/Preamp with lots and lots of output voltage.)
Moral of story - ACA amp can drive most, if not all speakers. If you don't have enough volume a preamp can be useful to add system gain.
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@6L6. I assume that adding system gain by using a preamp may be useful for purposes other than increasing the amp volume. It seems to me that the addition of gain may make the output of the amp more dynamic and therefore increase the sound stage and the quality of the music. I also assume there are limits to the amount of gain you can add without clipping or distortion. Are these assumptions correct or not?
I had the same concerns as you and ran that test. The results were surprising. After I purchased a set of ACA boards knowing that it's 8 watts would drive my 88db speakers to well beyond the levels I listen at in my small living room.
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Heat management
My setup dictates that the amp will be in an enclosed entertainment center. It does have some venting out the back panel where some large cutouts are for wire management but in closed on the other three sides. All my equipment is in there, preamp, dac, phono amp, turntable as well so I don't want to create an oven. I plan to get the mini Dissipante 3U chassis to provide a bit more heatsink than standard but of course the same heat will be dissipated regardless of heat sink size. Any tips for making this work?
My setup dictates that the amp will be in an enclosed entertainment center. It does have some venting out the back panel where some large cutouts are for wire management but in closed on the other three sides. All my equipment is in there, preamp, dac, phono amp, turntable as well so I don't want to create an oven. I plan to get the mini Dissipante 3U chassis to provide a bit more heatsink than standard but of course the same heat will be dissipated regardless of heat sink size. Any tips for making this work?
Drill a few holes on the bottom of the entertainment center. And yes, more heatsink means nothing if there's no movement of air.
I've installed quiet computer case fans in the entertainment center in cases such as this with great effect. Either blow it on the hot thing or place the hot thing on the newly drilled holes and have the fan suck the air out of the case.
I've installed quiet computer case fans in the entertainment center in cases such as this with great effect. Either blow it on the hot thing or place the hot thing on the newly drilled holes and have the fan suck the air out of the case.
That's correct - once the amp clips any additional gain doesn't do you any good. Hence the exact reason why preamps have volume controls.
Tannoy Proto-J's are rated by the manufacturer as 90db 1W/1M and 6ohm nominal.
Run the test. You are going to be amazed with the output.
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Is there an easy way to implement some form of clipping indicator, like Rod Elliots project 23?
Power Amp Clipping Indicator
I know people keep saying there is plenty of output, but a clipping indicator may put peoples minds at ease (it would mine). Does the ACA clip in a very hard manner or a more soft valvey fashion?
Go my boards built up,
going for a PSU in the case... looking snug!
https://lh3.googleusercontent.com/m...p2h_Mt3-eZVL8QJ8FtXjeh62mQr7Odj=w1604-h903-no
Power Amp Clipping Indicator
I know people keep saying there is plenty of output, but a clipping indicator may put peoples minds at ease (it would mine). Does the ACA clip in a very hard manner or a more soft valvey fashion?
Go my boards built up,
going for a PSU in the case... looking snug!
https://lh3.googleusercontent.com/m...p2h_Mt3-eZVL8QJ8FtXjeh62mQr7Odj=w1604-h903-no
ACA completed! It took me a bit more than the six hours stated in the guide but I did it in a day.
Now I'm setting the bias and I'm a bit worried because I might have touched two pins of Q1 at the same time with the DMM. Im talking about the center pin and the pin closer to the pot. I don't have any clip leads and measuring while adjusting is indeed a bit tricky.
Now, I didn't cause any sparks to fly and there was no sudden failure but I'm worried that I might have done some damage to Q1. Would it be a problem (leading to possible damage of Q1) if both pins are touched with the DMM lead at once?
Now I'm setting the bias and I'm a bit worried because I might have touched two pins of Q1 at the same time with the DMM. Im talking about the center pin and the pin closer to the pot. I don't have any clip leads and measuring while adjusting is indeed a bit tricky.
Now, I didn't cause any sparks to fly and there was no sudden failure but I'm worried that I might have done some damage to Q1. Would it be a problem (leading to possible damage of Q1) if both pins are touched with the DMM lead at once?
It’s always difficult to hold 2 test leads on the components while watching the meter and adjusting a pot. The build guide suggests using clip leads instead of the meter lead probes.
The fact that it still functions normally is a good indicator that no damage was done. It looks like you would have momentarily shorted the Source to Drain of Q1. Luckily, that is not going to do any damage in this circuit. Since Q2 is a current source, the current that would flow is limited and for a short duration shouldn’t cause any harm. It is a good reminder to use clip leads next time- and always power down the circuit before you attach any clip leads.
Happy listening
The fact that it still functions normally is a good indicator that no damage was done. It looks like you would have momentarily shorted the Source to Drain of Q1. Luckily, that is not going to do any damage in this circuit. Since Q2 is a current source, the current that would flow is limited and for a short duration shouldn’t cause any harm. It is a good reminder to use clip leads next time- and always power down the circuit before you attach any clip leads.
Happy listening
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A few years after doing this with our first daughter, it was time to build a music system with our second daughter. She just turned 11 and has a growing interest in music and all things science related. So, I gathered all of the necessary parts and did the pre-work of fabricating an amplifier chassis and matching set of speaker cabinets for her. She was THRILLED to open a present with all of the parts for an Amp Camp Amp and a pair of speakers!
We spent part of the weekend with the soldering iron making stinky smoke at the kitchen table. She measured all of the parts, bent all of the resistor legs so they'd fit in the boards, applied the solder, and trimmed things flush on the other side. I had previously cut, drilled, and finished a nice chunk of figured walnut to serve as the chassis.
After the amp was completed, we moved on to the speakers. They are made from 18mm BB ply and a slab of walnut for the front baffle. We stuffed the cabinets, soldered the binding posts, wired the drivers (Mark Audio CHR-70), and then secured everything to cabinets.
She was VERY excited to have built her own amplifier and speakers! She kept asking my wife to take pictures while we worked so she can show her friends at school. Tonight we'll get everything set up in her bedroom and have our first listen.
After five years, our first daughter has started dropping hints that she doesn't think her amplifier goes loud enough any more (she's 15 now). My wife and I seem to disagree...
We spent part of the weekend with the soldering iron making stinky smoke at the kitchen table. She measured all of the parts, bent all of the resistor legs so they'd fit in the boards, applied the solder, and trimmed things flush on the other side. I had previously cut, drilled, and finished a nice chunk of figured walnut to serve as the chassis.
After the amp was completed, we moved on to the speakers. They are made from 18mm BB ply and a slab of walnut for the front baffle. We stuffed the cabinets, soldered the binding posts, wired the drivers (Mark Audio CHR-70), and then secured everything to cabinets.
She was VERY excited to have built her own amplifier and speakers! She kept asking my wife to take pictures while we worked so she can show her friends at school. Tonight we'll get everything set up in her bedroom and have our first listen.
After five years, our first daughter has started dropping hints that she doesn't think her amplifier goes loud enough any more (she's 15 now). My wife and I seem to disagree...
Attachments
Great job! What did you use for a chassis before you made the wood faceplate, or did you fab the entire chassis?
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