Amp Camp Amp

[MrBoat]

@MrBoat
I like how you did these as mirror-images! I didn't really catch that until the last pic. Maybe a little accent lighting down the middle would look sweet sitting in a rack!

Admittedly, I mostly only photo'd one amp due to redundancy so it would not have shown a mirror theme until both face plates were on.

These should be a nice addition to my equipment shelves. on either side of the (I need to paint it black at some point) Behringer amp, perhaps.

I certainly have enough LED's. Being that you have to pretty much buy a hundred of them at a time.

 

[slipperybidness]

These things have turned a corner for me with regard to how I think about power, or what many of us are actually using at around the reference level or even beyond realm. At least those of us with average sized rooms and relatively sensitive speakers. Perplexing to someone like me, who has always approached audio in terms of 'hundreds' of watts.

My older car stereo, which is also a (Alpine) mosfet amp, claims 18 watts. I thought it was going to be a dog or, not much better than a factory unit from the 70's-80's but it is quite loud and sounds very nice.

Another thing I notice in use is, when not hooked up or the music on, they heat up a lot more. When the music is playing, they just do get warm and even cool off noticeably from the idle status.

Yeah, I don't think I have ever seen or heard anything Alpine that was disappointing!

That does seem a bit odd with the heat thing. You may have mentioned it earlier, but these are Class A biased?

Yup, Nelson Pass has his "other company" called "First Watt". A call back to the old saying "the first watt is the most important".

For most users, in most rooms, all that extra power is for the headroom to hit the dynamic peaks, not for continuous power supply.

 

[MrBoat]

Yeah, I don't think I have ever seen or heard anything Alpine that was disappointing!

That does seem a bit odd with the heat thing. You may have mentioned it earlier, but these are Class A biased?

Yup, Nelson Pass has his "other company" called "First Watt". A call back to the old saying "the first watt is the most important".

For most users, in most rooms, all that extra power is for the headroom to hit the dynamic peaks, not for continuous power supply.

Yes, Class A.

At first I turned them on and let them warm up again to check the bias voltages to see if they had changed between a couple heating/cooling cycles so they were a bit warm by the time I went to hook up the speakers to them. Then I noticed while playing they had cooled quite a bit. At first I thought it was because I got up and the ceiling fan was hitting them more directly with me out of the way but, even after I sat back down to listen for a spell they never really did get that warm again.

I did have the top covers on and I suppose that could complete the link to the rest of the mass to act as a bigger heat sink, but that seems iffy.

 

[slipperybidness]

Yes, Class A.

At first I turned them on and let them warm up again to check the bias voltages to see if they had changed between a couple heating/cooling cycles so they were a bit warm by the time I went to hook up the speakers to them. Then I noticed while playing they had cooled quite a bit. At first I thought it was because I got up and the ceiling fan was hitting them more directly with me out of the way but, even after I sat back down to listen for a spell they never really did get that warm again.

I did have the top covers on and I suppose that could complete the link to the rest of the mass to act as a bigger heat sink, but that seems iffy.

I suppose this observation must be explainable with the bias point (Quiescent Point) and the load line when biased to pure class A. Likely, @TLS Guy may enlighten us.

Now, we are getting technical, and may be over your head, but this diagram shows the gist of what I'm getting at here:

 

[ski2xblack]

They're not pp types biased in class A, they're single ended. Output device (only one in the signal path) fully conducts even with no signal, producing lots of heat. With a signal, some of that goes into moving the speakers instead, thus less heat. It's also why psrr is so important, as supply hum will be amplified.

 

[MrBoat]

They're not pp types biased in class A, they're single ended. Output device (only one in the signal path) fully conducts even with no signal, producing lots of heat. With a signal, some of that goes into moving the speakers instead, thus less heat. It's also why psrr is so important, as it will be amplified.

"pp"? Push-pull? "psrr?"

 

[ski2xblack]

Yes, pp = push pull. psrr= power supply ripple rejection.

 

[MrBoat]

I did manage to get my inputs/outputs in. These were not well suited for .250". I cut a hollow shaped like these .125" covers with the band saw, and then welded up the band saw entry/exit and resanded the plates. Could have used the milling machine at work, but this was probably 3X faster doing it this way.

The power in will be separate. Not exactly sure how I want to do that or, what kind of plug I want to use yet.

RCA in on top. Speaker +- on bottom.

The functional amp part is a joke compared to building a chassis from scratch. I was done with the board in an hr.

 

[MrBoat]

These things actually sound pretty darn nice. Of course it's just an amplifier so maybe it's my speakers that sound nicer but this is a compliment for whatever it is that it does add. Will get around to hooking them up to the Tempests at some point. Still have a good feeling about that matchup.

 

[ski2xblack]

I don't think it's merely your speakers. You've built yourself the ss equivalent of single ended 300b amp (albeit ones that lack the ridiculous expense and hassle of tubes). Dollars to donuts you could pick them out in an a/b comparison with conventional amps.

Anywho, my hats off to you for not only building them, but also sharing the process with us. Thanks for your awesome contributions to the forum Mr Boat!

 

[MrBoat]

I don't think it's merely your speakers. You've built yourself the ss equivalent of single ended 300b amp (albeit ones that lack the ridiculous expense and hassle of tubes). Dollars to donuts you could pick them out in an a/b comparison with conventional amps.

Anywho, my hats off to you for not only building them, but also sharing the process with us. Thanks for your awesome contributions to the forum Mr Boat!

Definitely one of the audio DIY things worth doing. I would encourage anyone to try it.

Also appreciate the good help and inspiration I have gotten here.

I was listening to music last night and it was very good and it occurred to me just how enriching this hobby can be. Now with all of the inside info at our fingertips, and with being able to rub elbows with the rock stars of this tech almost directly, it doesn't even have to be expensive.

 

[slipperybidness]

Yes, pp = push pull. psrr= power supply ripple rejection.

I always see "PSRR" as Power Supply Rejection Ratio.....meaning that I think it actually incorporates a little more than just ripple rejection (other noise, etc).

 

[MrBoat]

I don't think it's merely your speakers. You've built yourself the ss equivalent of single ended 300b amp (albeit ones that lack the ridiculous expense and hassle of tubes). Dollars to donuts you could pick them out in an a/b comparison with conventional amps.

Anywho, my hats off to you for not only building them, but also sharing the process with us. Thanks for your awesome contributions to the forum Mr Boat!

I am back to report after a bit more messing with these amps. This time, hooked to the pre-outs of my Denon 3805 alongside of the subs and bass management, along with the little wide band oddities. I have to say, this is an excellent audio experience. These amps/speakers sound sweet and you are right, there is a sonic difference and it I do enjoy it a lot.

I could live well with this and it gets quite a bit louder than I was expecting and the more I listen, all I can say is, wow.

I will have to get some proper RCA cables but that's where these amps are going to be put thru their paces out here with my nightly listening marathons.

And as I noticed before, these things don't get very warm under load.

Integrated it into my system and finally hooked the amps up to the Tempests. Takes about half the power that it took to drive the wide band speakers and the sound is marvelous. With regard to scale of size though, it's right either way. With the Tempests, it can get too loud in this room. Either way, I could not make the amps clip/distort before I would otherwise wave the white flag SPL wise.

I will probably either dim the LEDs or fire them under the amps, although, the camera is adding a lot of emphasis there. The covers on the amps I actually prefer they lift off. The end plates can hold them relatively snug. Also, with regard to vent holes, these will not need them and I like the idea of keeping the dust out.

If I were to describe the performance, these are not short on detail. For lack of a better description, I would have to notice an emphasis on clarity and these do not hold anything back. What's clouding my judgement is the same thing that happened to me with the little wide band driver speakers. Audiophile quality sound for such a low price and sans much in the way of complications. I believe anyone with a modest living space, could take a pair of these a pair of solid performing, full range speakers, and live happily ever after.

Hat's off to Nelson Pass for sharing this.

 

[ski2xblack]

Uh oh, you've used "sweet" as a description, do we need to shoot you and feed you to the fish now?

That peculiar clarity is the hallmark of the single ended amps. It's quite seductive.

 

[MrBoat]

Uh oh, you've used "sweet" as a description, do we need to shoot you and feed you to the fish now?

That peculiar clarity is the hallmark of the single ended amps. It's quite seductive.

Yeah but, I didn't say chocolaty or velvety or any of the other "ty" words.

 

[MrBoat]

Still on with these amps and the Fusion-12's. Really good stuff.

I did dim the LED's.

 

[MrBoat]

Going to end up building a couple more amps. Another pair of these with the new version of the board that spaces the MOSFETs more evenly on the heat sinks coming off each narrow end of the boards. With the old style board I used, I was sorely tempted to move the MOSFETs and use jumper wires to the positions on the boards.

Also another Pass DIY amp, which is the F5. I have other matched pairs of the necessary Toshiba JFETs that would be a shame not to install in something. The F5 is more powerful than the standard Amp Camp Amp that puts out around 25w, IIRC. That would be great for some of my less sensitive speakers or some full range builds I have on mothballs currently.

Still scheming a way to build heat sinks from raw stock without having to buy yet one more wavy finned sink that we see on many amps these days, nor the cheaper ones from overseas. Anyway, I have some ideas in mind for that.

I reckon my next research is going to be with power supply how-to's.

 

[slipperybidness]

Going to end up building a couple more amps. Another pair of these with the new version of the board that spaces the MOSFETs more evenly on the heat sinks coming off each narrow end of the boards. With the old style board I used, I was sorely tempted to move the MOSFETs and use jumper wires to the positions on the boards.

Also another Pass DIY amp, which is the F5. I have other matched pairs of the necessary Toshiba JFETs that would be a shame not to install in something. The F5 is more powerful than the standard Amp Camp Amp that puts out around 25w, IIRC. That would be great for some of my less sensitive speakers or some full range builds I have on mothballs currently.

Still scheming a way to build heat sinks from raw stock without having to buy yet one more wavy finned sink that we see on many amps these days, nor the cheaper ones from overseas. Anyway, I have some ideas in mind for that.

I reckon my next research is going to be with power supply how-to's.

Keep in mind, you can get away with "less heatsink" if you add fans. But, I personally prefer passive cooling vs. active cooling. Fans add noise, and add a new failure point.

I started my amp-building journey with an extended study of power supplies, so I should be a good resource to help you out there.

 

[MrBoat]

Keep in mind, you can get away with "less heatsink" if you add fans. But, I personally prefer passive cooling vs. active cooling. Fans add noise, and add a new failure point.

I started my amp-building journey with an extended study of power supplies, so I should be a good resource to help you out there.

The thing I like least about fans is dust. I'm always having to clean the fan and internals on my desktop pc.

Will appreciate the help. This should be a fun project. I have certainly had fun with the first amp and I do enjoy using it. I've lucked out with the first build. I have had no (unwanted) noise whatsoever.