I've had a few questions about the Tripath mods that I made, so let me post them publically:
1) input transformer:
I use the JT-11P-1 as indicated in the Jensen literature using an impedance network on the input side. I don't have the literature right in front of me, but I seem to recall that the Red lead was + input (hot lead on RCA jack; pin 2 on XLR), the Brown lead - (isolated ground on RCA; pin 3 on XLR; BTW, pin1 should go to analog ground) input, with the Yellow and Orange being the corresponding outputs going to the input on the Tripath board. The orange, white, and black go to the analog ground on the Tripath board. All leads were tightly twisted, but not shortened nor otherwise fiddled with; no extra shielding is necessary.
Now on one channel, I reversed the inputs, putting Red on RCA isolated ground (pin 3 on XLR) and Brown on central hot RCA (pin 2), to put the inputs out of phase. This is to reduce power supply pumping. The ouput on one channel was also reversed for phase to keep absolute phase for the whole amp. (Please see my original post, I believe I discussed this ; also see Tripath documentation, one of the app notes as I recall.)
I left the cap in the signal path(C13/16), but replaced it with a 1 microfarad film cap (instead of the stock electrolytic). This is due to the 5V (maybe it's 2.5V, I forget) DC bias applied to the input. The cap blocks the DC bias from the source, which is now the secondary from the transformer. Between the secondary and this input cap is where the impedance network can be placed.
What I used was a 15k resistor. The reason is that I changed the series input resistor (R8/9) from 49K to 25K. There is an internal 5K resistor, meaning that the input impedance is now 30K (25K + 5K). By placing 15K in parallel with this, the input impedance is now effectively 10K (15K || 30K = 10K). This is a simple solution and avoids the more complex impedance matching suggested by Jensen for non-10K loads.
I did this for each channel as I am running the amp in stereo, not bridged, mode. I get plenty of power without going to a bridged configuration.
2) power supply
I made a very large power supply (again refer to the original posting at http://www.diyaudio.com/forums/showthread.php?threadid=1814). I used two 600 VA transformers, one for the positive voltage and one for the negative; this means two bridge recitifiers (using 2 bridge rectifiers lowers the noise floor, by I believe about 12 dB). Each transformer was had two 30VAC secondaries; these were put in series to generate 60VAC for each bridge rectifier. In turn, this generated about +/- 84VDC supplies. This was then filtered with two 12,000 microfarad caps (100V), one for each rail.
Next, the +/- supply was filtered with a 12 mH choke (one for each rail), and onto a another pair of 12,000 microfarad caps (100V), onto a set a line fuses, and from there directly to the Tripath board. This created a C-L-C filtered supply. The wires running to the Tripath board from the power supply boards were the supplied wires (I just cut off the jacks), so my final power supply is maybe 4 inches or so of wire from the amp.
3) output filter
I had a small problem crop up, that was helpfully solved by Kevin at Tripath (very nice person to deal with BTW; he said all new boards from Tripath have upgraded components, so many of the changes we've done will already be done for future DIYers--nice!). One channel this weekend smelled like a burned out cap, although the unit was running. I opened it up and found one output resistor (R14) a 33 ohm/2W was destroyed. I replaced it with a 22 ohm/3W resistor and kept the 0.22 microfarad PP cap I'd already installed there. The unit worked but the output load resistor (470 ohm got REALLY warm), while the other channel was cool to touch.
I measured the DC offset and my multimeter began reading frequencies instead of voltages. This is a very important clue: the output filter was still broken and the ripple resonance current was overheating the output load resistor. What had happened was 0.22 cap had failed, leading to the resistor failure. When I replaced the resistor, the cap was still 'missing' from the circuit allowing 600kHz ripple current to overheat the 470 ohm resistor and triggering the frequency read-out on my multimeter. So a word to the wiz: if your DC is fluctuating or impossible to set (and you don't have a scope to verify it), you most likely have a problem with the output filter. Replace or resolder the output cap with a polypropylene unit and all should be fine.
4) cost
Earlier in the thread I mentioned that I seemed to recall that the cost was $399 for the board; mea culpa, it is $299 according to my notes. This is what i paid last fall, better to contact Tripath directly to confirm latest prices.
I hope this helps,
Robert Jones
1) input transformer:
I use the JT-11P-1 as indicated in the Jensen literature using an impedance network on the input side. I don't have the literature right in front of me, but I seem to recall that the Red lead was + input (hot lead on RCA jack; pin 2 on XLR), the Brown lead - (isolated ground on RCA; pin 3 on XLR; BTW, pin1 should go to analog ground) input, with the Yellow and Orange being the corresponding outputs going to the input on the Tripath board. The orange, white, and black go to the analog ground on the Tripath board. All leads were tightly twisted, but not shortened nor otherwise fiddled with; no extra shielding is necessary.
Now on one channel, I reversed the inputs, putting Red on RCA isolated ground (pin 3 on XLR) and Brown on central hot RCA (pin 2), to put the inputs out of phase. This is to reduce power supply pumping. The ouput on one channel was also reversed for phase to keep absolute phase for the whole amp. (Please see my original post, I believe I discussed this ; also see Tripath documentation, one of the app notes as I recall.)
I left the cap in the signal path(C13/16), but replaced it with a 1 microfarad film cap (instead of the stock electrolytic). This is due to the 5V (maybe it's 2.5V, I forget) DC bias applied to the input. The cap blocks the DC bias from the source, which is now the secondary from the transformer. Between the secondary and this input cap is where the impedance network can be placed.
What I used was a 15k resistor. The reason is that I changed the series input resistor (R8/9) from 49K to 25K. There is an internal 5K resistor, meaning that the input impedance is now 30K (25K + 5K). By placing 15K in parallel with this, the input impedance is now effectively 10K (15K || 30K = 10K). This is a simple solution and avoids the more complex impedance matching suggested by Jensen for non-10K loads.
I did this for each channel as I am running the amp in stereo, not bridged, mode. I get plenty of power without going to a bridged configuration.
2) power supply
I made a very large power supply (again refer to the original posting at http://www.diyaudio.com/forums/showthread.php?threadid=1814). I used two 600 VA transformers, one for the positive voltage and one for the negative; this means two bridge recitifiers (using 2 bridge rectifiers lowers the noise floor, by I believe about 12 dB). Each transformer was had two 30VAC secondaries; these were put in series to generate 60VAC for each bridge rectifier. In turn, this generated about +/- 84VDC supplies. This was then filtered with two 12,000 microfarad caps (100V), one for each rail.
Next, the +/- supply was filtered with a 12 mH choke (one for each rail), and onto a another pair of 12,000 microfarad caps (100V), onto a set a line fuses, and from there directly to the Tripath board. This created a C-L-C filtered supply. The wires running to the Tripath board from the power supply boards were the supplied wires (I just cut off the jacks), so my final power supply is maybe 4 inches or so of wire from the amp.
3) output filter
I had a small problem crop up, that was helpfully solved by Kevin at Tripath (very nice person to deal with BTW; he said all new boards from Tripath have upgraded components, so many of the changes we've done will already be done for future DIYers--nice!). One channel this weekend smelled like a burned out cap, although the unit was running. I opened it up and found one output resistor (R14) a 33 ohm/2W was destroyed. I replaced it with a 22 ohm/3W resistor and kept the 0.22 microfarad PP cap I'd already installed there. The unit worked but the output load resistor (470 ohm got REALLY warm), while the other channel was cool to touch.
I measured the DC offset and my multimeter began reading frequencies instead of voltages. This is a very important clue: the output filter was still broken and the ripple resonance current was overheating the output load resistor. What had happened was 0.22 cap had failed, leading to the resistor failure. When I replaced the resistor, the cap was still 'missing' from the circuit allowing 600kHz ripple current to overheat the 470 ohm resistor and triggering the frequency read-out on my multimeter. So a word to the wiz: if your DC is fluctuating or impossible to set (and you don't have a scope to verify it), you most likely have a problem with the output filter. Replace or resolder the output cap with a polypropylene unit and all should be fine.
4) cost
Earlier in the thread I mentioned that I seemed to recall that the cost was $399 for the board; mea culpa, it is $299 according to my notes. This is what i paid last fall, better to contact Tripath directly to confirm latest prices.
I hope this helps,
Robert Jones
hi.
m.parigi i agree and as you can see i tried to help at first (meaning before i/we got side tracked by the lies from peter thomsen/av reality).
did you find a solution to your problems?
feel free to email me directly if you think i can help.
let me just say this ; i posted on av reality site and asked if he was interested in a/b comparisons between his icepower amps and our amps , like we have dome here with the designer of the icepower boards present.
this gave a hostile and lying response on his board and several emails of same kind.
on this board and on av reality website is a bunch of lies , like i said before i dont think i want to go into details about it , if somebody finds it interesting feel free to start a new thread for this.
let me also just point out that i asked about specs for lc audio amplifier and this actually gave some kind of proof that the specs were 100-200 times off , some "mistake" if you ask me.
as for giving "good advice" about seeing professional help or whatever , how low can you go peter??
i can fully understand that buying a $60 module and putting it into a "fancy" case and selling the complete self-proclaimed "high-end" amp for $1500 (just a guess as nobody gave the real price)
can make a very good business if you can find somebody willing to pay.
i can also understand that no comparisons to icepower modules or other amplifiers are welcome , for an unbiased opinion see the link i made.
you are right that class-d.org hasnt tested or heard our amplifiers , we design and sell oem amplifiers to a number of companies all over the world (this puts the funny remarks from peter and others about losing sales or whatever a bit into context i think).
maybe we will begin to sell them on a broader scale later , maybe.
best regards - k madsen - www.cadaudio.dk
brad, to your information a guy asked about lc pwm amplifiers in usenet and the repply was "not very good as amplifiers at all but they could certainly receive radio , you could even change the program by turning the inductor on the top of the board".....
m.parigi i agree and as you can see i tried to help at first (meaning before i/we got side tracked by the lies from peter thomsen/av reality).
did you find a solution to your problems?
feel free to email me directly if you think i can help.
let me just say this ; i posted on av reality site and asked if he was interested in a/b comparisons between his icepower amps and our amps , like we have dome here with the designer of the icepower boards present.
this gave a hostile and lying response on his board and several emails of same kind.
on this board and on av reality website is a bunch of lies , like i said before i dont think i want to go into details about it , if somebody finds it interesting feel free to start a new thread for this.
let me also just point out that i asked about specs for lc audio amplifier and this actually gave some kind of proof that the specs were 100-200 times off , some "mistake" if you ask me.
as for giving "good advice" about seeing professional help or whatever , how low can you go peter??
i can fully understand that buying a $60 module and putting it into a "fancy" case and selling the complete self-proclaimed "high-end" amp for $1500 (just a guess as nobody gave the real price)
can make a very good business if you can find somebody willing to pay.
i can also understand that no comparisons to icepower modules or other amplifiers are welcome , for an unbiased opinion see the link i made.
you are right that class-d.org hasnt tested or heard our amplifiers , we design and sell oem amplifiers to a number of companies all over the world (this puts the funny remarks from peter and others about losing sales or whatever a bit into context i think).
maybe we will begin to sell them on a broader scale later , maybe.
best regards - k madsen - www.cadaudio.dk
brad, to your information a guy asked about lc pwm amplifiers in usenet and the repply was "not very good as amplifiers at all but they could certainly receive radio , you could even change the program by turning the inductor on the top of the board".....
How did I ever miss this food fight????
Is it too late too pour some gasoline the fire? Gee, I hope not.....
Anyway, I heard the "eAR amps" referred to at a DIY buddy's place some months ago. I have to admit that they sound a lot better than I would have thought.
But......having said that.........
Just because they have modules that only cost $60(?) is a moot point. Let me see.......2 x $60 is $120; add at least another $60 for a power transformer, and a similar amount for 4 filter caps.....that gives us $240 so far. And a chassis, never cheap. And some PCBs........connectors for ins and outs. Yeah, if I made a commercial product like that it would cost at least $2000 to the end user. So, is he getting rich, in underhanded manner, as some have seem to suggest? No, I think not. I do not care how or what an amp is built with, it is not cheap to design, build, warehouse, distribute, warranty, and sell one. So there. If anyone thinks different: go try it. Don't whine to me when you find out how hard it is.
Now, on the other side of the coin..........
This one of the most.......uh........unusual pieces of electronics that I have seen. Beauty is in the eyes of the beholder, but I wonder what in the world the guy who thought this up was thinking. It is a nightmare to connect speakers leads to: especially if you have some big fat ones that don't fit onto a Speakon connector. You will have to swap them out (which may be hard), and how you are going to bend a big fat cable to fit up in there.......along with your greasy, sweaty hands is something that I will not have to worry about.
Remind me if I ever make amps again, not make them look like these. Although the idea of a stainless steel chassis is idea worth stealing. (Pun not intended.)
Is it too late too pour some gasoline the fire? Gee, I hope not.....
Anyway, I heard the "eAR amps" referred to at a DIY buddy's place some months ago. I have to admit that they sound a lot better than I would have thought.
But......having said that.........
Just because they have modules that only cost $60(?) is a moot point. Let me see.......2 x $60 is $120; add at least another $60 for a power transformer, and a similar amount for 4 filter caps.....that gives us $240 so far. And a chassis, never cheap. And some PCBs........connectors for ins and outs. Yeah, if I made a commercial product like that it would cost at least $2000 to the end user. So, is he getting rich, in underhanded manner, as some have seem to suggest? No, I think not. I do not care how or what an amp is built with, it is not cheap to design, build, warehouse, distribute, warranty, and sell one. So there. If anyone thinks different: go try it. Don't whine to me when you find out how hard it is.
Now, on the other side of the coin..........
This one of the most.......uh........unusual pieces of electronics that I have seen. Beauty is in the eyes of the beholder, but I wonder what in the world the guy who thought this up was thinking. It is a nightmare to connect speakers leads to: especially if you have some big fat ones that don't fit onto a Speakon connector. You will have to swap them out (which may be hard), and how you are going to bend a big fat cable to fit up in there.......along with your greasy, sweaty hands is something that I will not have to worry about.
Remind me if I ever make amps again, not make them look like these. Although the idea of a stainless steel chassis is idea worth stealing. (Pun not intended.)
Putting out fire...with gasoline
My Tripath 0104 had a new AR "ice" amp for breakfast in a listening test at a friends house.(For several pairs of ears). But then again, it has been terrible unstable, so I probably need to rewire/rebuild it to cure the unwanted oscillations & self-destruction of output devices.
Arne K
My Tripath 0104 had a new AR "ice" amp for breakfast in a listening test at a friends house.(For several pairs of ears). But then again, it has been terrible unstable, so I probably need to rewire/rebuild it to cure the unwanted oscillations & self-destruction of output devices.
Arne K
Re: How did you do it?
m.parigi, Maybe the shielding is picking up noise and introducing it into the input of the transformer. Consider using two RCA cables with both outer shield conductors going to ground while each inner goes to the transformer input. You can try converting to a single cable at the input of the amp on the cabinet.
m.parigi, Maybe the shielding is picking up noise and introducing it into the input of the transformer. Consider using two RCA cables with both outer shield conductors going to ground while each inner goes to the transformer input. You can try converting to a single cable at the input of the amp on the cabinet.
Hi guys, I thought this thread was long dead, but I guess some fire's still burning under the ashes...
Anyway, here's how it went with my Tripath amp. I carefully followed all of RLJones directions, plus all other help from the forum's members, etc.
No matter how much I tweaked it, the *******' board kept blowing output devices and/or destroying capacitors and resistors (don't remember which ones, it happened several times...).
I was amazed at the instability of the setup: I had it work "correctly" for half a day then, out of the blue, it would start smoking and, after a couple of seconds, it would emit a loud whistle and a bang... and die. Please note that it was in the middle of a CD play, without me being even close to it!
The last straw was when I found out that:
a) in one instance the output FET's had been blown open, that is the full +/-75V DC was going to the speakers!
b) My ribbon speakers (tweeters) were getting VERY hot! Don't ask me why, I can only speculate that some RF was making it to them...
Anyway, at this point I decided to cut the losses and not to jeopardize my precious speakers, so I dumped the whole project and I simply threw away the board.
Since I had already invested a substantial amount of money in the power supply and enclosure, I've built a power amp by using the THEL power amp modules (www.thel.de).
I'm going to start testing them this weekend...
Since I came on late.......
What I have heard.......
Tripath has dead time issues, which causes punch-through problems. Which may be why yours blows up.
Yeah, transformers might be a good idea around this PWM stuff. I don't care who makes them, and how, they will generate tons of EMI. Don't think that will cause failures, just lead to really bad sound.
But not load dependent????? They all have a LPF on the output, and the load impedance will affect frequency response. To me, that is load dependent.
Jocko
What I have heard.......
Tripath has dead time issues, which causes punch-through problems. Which may be why yours blows up.
Yeah, transformers might be a good idea around this PWM stuff. I don't care who makes them, and how, they will generate tons of EMI. Don't think that will cause failures, just lead to really bad sound.
But not load dependent????? They all have a LPF on the output, and the load impedance will affect frequency response. To me, that is load dependent.
Jocko
I recently came across an EB-TA0103A Evaluation Board and am planning ot build an amplifier based on it.
For the power supply - I was thinking of using two of these SMPS:
For a volume control I thought one of these might be nice:
Stereo Stepped Attenuator
Would the 50K value be appropriate?
And this seems like good value for a chassis to put it all into:
Black Metal Chassis
Any thought's, ideas, warnings or other advice would be appreciated.
For the power supply - I was thinking of using two of these SMPS:
For a volume control I thought one of these might be nice:
Stereo Stepped Attenuator
Would the 50K value be appropriate?
And this seems like good value for a chassis to put it all into:
Black Metal Chassis
Any thought's, ideas, warnings or other advice would be appreciated.
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