I do mostly tube amps but have experimented with building discrete op amp preamps for use with tube amps. I recently adapted a six channel amplifier from a 94 Cadillac to home use. It has two sets of three way active crossovers into 20 watt amps.Treble, Bass and Midrange. It is powered by a modified computer power supply @12 volts. Your local junk yard may have them. They were used in the deluxe GM cars in the 90s. You can also harvest some good speakers from the same cars, all at rock bottom prices. It is not an easy conversion, as schematics are difficult to come by, but it was a fun project.
Yes. I was at the Toronto meet. At the meet, we listened to a chip amp (LM3886 based I think), a 4 W KT88 SE tube amp, very briefly a Dyna Sca35 clone tube amp, and the TPA3116.
The following comments are based on recollection and very brief exposure to those amps, so do not hold me to it:
- the KT 88 SE sound very nice on vocals and instruments, " a lot of air", very natural human voice. The base was not bad but as expected, not as deep and punchy as SS amps
- the chip amp sound alright, pretty even across the board, nothing offended but nothing stood out either.
- Compare to KT88 SE, the Dyna Sca35 clone has a little more SS character. The base is slightly better, I prefer the KT88 SE for human voice. But overall, quite nice sounding.
- The TPA3116 was a big surprise. Mainly because of its minute size and the big sound it was making. By far, it gave the deepest and punchiest base among this group. And it played loud. The sound stage was quite wide and deep. The high has some nice sparkles to it. I like it better than the chip amp. I still have to say that the KT88 SE has "nicer" human voice (in my opinion).
Personally, I do not think the TPA3116 sound like tube amps [I listen to a Melody SP3II (5881 based) at home]. All the amps we listened to on that day sounded a little diffferent. None of them sounded "bad".
By the way, the sound changed when we swapped the amps between the LDR and the TVC. Although not huge, there were distinct differences that everyone can pick out right away.
As I said, it was this exposure to the TPA3116 amp that got me interested in Class D amp. I have just finished the 3123 amp kit that I bought from Sure ELectronic on Ebay (same as the Jerryelectronic one I think). I am going to hook it up and listen to it. But I still want to build that 3116 amp sometime in the future.
Regards,
Thanks for the feedback and your impressions of the various amps. I have something to look forward to then when I finish building the 3116. Although I imagine the sound of the 3118 is very similar, just less power, and I am not anywhere near using all the power that the 3118 has. I really like the sound of the 3118 that I have actually put away my old Yamaha RX360 45 watt/ch amp and placed the diminutive 3118 foam core amp atop my carousel CD player as the main amp. It looks kind of incongruous to have this huge CD player deck topped by this tiny amp. But the sound is BIG, and consistent with your comments on how it sounds. Do you like the sound of a LDR preamp? I have never heard one before but that sounds like an interesting DIY project. Below are some photos of my current setup with the 3118 as the main amp.
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Here it what the adapted Delco Auto Amp looks like after modification. It has 11 channels, six separated treble, mid range, and bass for the left and right sides and four channels of only treble and mid range, and a center channel that combine both the left and right channels. Power is 20 watts per channel and the separation is 12 db per channel. I added volume controls to the inputs and and modified a 400 Watt computer supply to power it.
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Ken,
Nice work on that box there Ken, clean workbench too
Thanks for sharing your tip on how to find a cheap 12 channel x 20 watt amp! Does it sound good? There is another thread on a single DSP+integrated amp that does 12 channels of surround sound, psychoacoustics, Dolby, etc, plus amp module for 20 watts/ch I think with ability to drive external MOSFETs for more. This is how they make HT boxes so cheap now. Anyhow I am looking into that option too - if a free eval board is available that would be pretty good.
http://www.diyaudio.com/forums/class-d/232598-d2-audio-bass-amp.html
Nice work on that box there Ken, clean workbench too
Thanks for sharing your tip on how to find a cheap 12 channel x 20 watt amp! Does it sound good? There is another thread on a single DSP+integrated amp that does 12 channels of surround sound, psychoacoustics, Dolby, etc, plus amp module for 20 watts/ch I think with ability to drive external MOSFETs for more. This is how they make HT boxes so cheap now. Anyhow I am looking into that option too - if a free eval board is available that would be pretty good.http://www.diyaudio.com/forums/class-d/232598-d2-audio-bass-amp.html
The quality sound is good but there are no EQ or level controls for the individual channels. EQ was only controlled from the dash console with the bass and treble controls. I've used it purely as an experimental amp and it is not part of my usual listening system. I believe it was marketed as a James B. Lansing (JBL) Custom System, to counter Lincolns marketing the "Bose" auto audio system.
Wushu,
That would be pretty cool if you can get Cristi to make complete amps. Do you have any of his other products? I can't be the only person to have built a diy amp with the 3118 so far. It is a great sounding amp and I am looking forward to the 3116 which should be arriving in the mail any day now. I am also intrigued by the TI TAS5630B that Mantabernd built (see class D photos thread). It is a 300 w/ch chip. Now that is some power. Here is the amp as implemented by Mantabernd. Can you believe this is his first smd project? The amp looks so pro....
That would be pretty cool if you can get Cristi to make complete amps. Do you have any of his other products? I can't be the only person to have built a diy amp with the 3118 so far. It is a great sounding amp and I am looking forward to the 3116 which should be arriving in the mail any day now. I am also intrigued by the TI TAS5630B that Mantabernd built (see class D photos thread). It is a 300 w/ch chip. Now that is some power. Here is the amp as implemented by Mantabernd. Can you believe this is his first smd project? The amp looks so pro....
I've used several of Cristi's amps, they are very very well designed and he has many happy customers. He just replied that he would consider designing an amp, possibly with onboard smps which is his specialty. I suggest anyone interested in these TPA chips head to the Class D Connexelectronic forum here to let him know there is interest for such an amp.
If it has built-in smps it has zero interest. Otherwise, I might be down for a couple of hundred of them if the price is right.
I agree that no built in SMPS is preferable. That's a lot of Boominators...
It might not just be for that...
But yes, it would become de facto standard recommended amp for Boominators if it's the right price and construction. Preferred size would be something that could be mounted directly on a standard half (or quarter) brick traverse dc-dc heat sink (google it if in doubt, as they are industry standards they're dirt cheap). Either a half or quarter inch. All SMT components on the down side towards the heat sink. All through hole components and connectors on the up side. Entire up side being ground plane.
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Just search for: "half brick heat sink" (or "quarter brick" or "Eight brick")
Almost all major heat sink manufacturers make these as standard products.
Transverse fin orientation is also called crosswise or vertical by some manufacturers.
Retail prices are generally under $5 a piece in single piece quantities.
Here's a sample pdf: http://www.aavid.com/sites/default/files/products/dc-dc/pdf/dcdc_Half.pdf
Almost all major heat sink manufacturers make these as standard products.
Transverse fin orientation is also called crosswise or vertical by some manufacturers.
Retail prices are generally under $5 a piece in single piece quantities.
Here's a sample pdf: http://www.aavid.com/sites/default/files/products/dc-dc/pdf/dcdc_Half.pdf
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Saturnus,
Good tip on industry standard heat sink. I am looking for one capable of dissipating 40 watts and cut-by-the-inch extruded aluminum profiles are coming up to be about $15.
If all you need is 30 w/ch, the TPA3118D2 can be constructed with the PCB serving as the heatsink so no external heatsink required. The ground plane connected with several vias soldered to metal pad on bottom side of IC serves as heat removal. There is not much heat to remove: music is about 10% peak duty factor at worst and a 90% efficient amp means that for 60 watts x 10% dissip = 6 watts, 6 watts x 10% duty cycle for music is < 1 watt dissipation. This explains why I can run it without the powerpad being soldered to the PCB. The 50 watt/ch TPA3116D2, TI recommends a tiny heatsink like 0.5 in wide x 3 in long strip of aluminum with some fins. I am taking a 3 in wide TO-3 heatsink stock and hacksawing a 0.5 in strip to make the heatsink.
Good idea to have thru holes on one side and SMD on other side. There is only the main power capacitor that is thru hole and that is because we are using bigger size (470 uF to 560 uF) than TI recommends (only 220 uF) which would be SMD, then no thru hole components at all.
Good tip on industry standard heat sink. I am looking for one capable of dissipating 40 watts and cut-by-the-inch extruded aluminum profiles are coming up to be about $15.
If all you need is 30 w/ch, the TPA3118D2 can be constructed with the PCB serving as the heatsink so no external heatsink required. The ground plane connected with several vias soldered to metal pad on bottom side of IC serves as heat removal. There is not much heat to remove: music is about 10% peak duty factor at worst and a 90% efficient amp means that for 60 watts x 10% dissip = 6 watts, 6 watts x 10% duty cycle for music is < 1 watt dissipation. This explains why I can run it without the powerpad being soldered to the PCB. The 50 watt/ch TPA3116D2, TI recommends a tiny heatsink like 0.5 in wide x 3 in long strip of aluminum with some fins. I am taking a 3 in wide TO-3 heatsink stock and hacksawing a 0.5 in strip to make the heatsink.
Good idea to have thru holes on one side and SMD on other side. There is only the main power capacitor that is thru hole and that is because we are using bigger size (470 uF to 560 uF) than TI recommends (only 220 uF) which would be SMD, then no thru hole components at all.
In a Boominator ambient temperature can climb to 35-40 degrees so a vastly oversized heat sink like a quarter brick quarter inch height is always a good idea. Especially since they cost very little and are an industry standard so it always have the same pre-made holes and you can source them from many different places.
You can even get ultra-low cost snap-in mounting bracket for these standard brick heat sinks. I realize that a flat piece of aluminium 3mm thick of the same size as the pcb would be more than enough heat sinking but that would actually cost several times more to get cut in size and pre-drilled with holes than these industry standard ones.
But no, the full 2x50W would be the goal. Although only used when used with batteries in series or a dc-dc converter.
Many of the better coils especially of the slightly lower cost type are also through-hole and would benefit from being on the opposite side as well so that their emitted noise basically only sees the ground plane.
You can even get ultra-low cost snap-in mounting bracket for these standard brick heat sinks. I realize that a flat piece of aluminium 3mm thick of the same size as the pcb would be more than enough heat sinking but that would actually cost several times more to get cut in size and pre-drilled with holes than these industry standard ones.
But no, the full 2x50W would be the goal. Although only used when used with batteries in series or a dc-dc converter.
Many of the better coils especially of the slightly lower cost type are also through-hole and would benefit from being on the opposite side as well so that their emitted noise basically only sees the ground plane.
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