My first limitation is while under warranty I can't mess with the insides of my amps... yet. Once I'm sure there are no defects I'll start tinkering with their insides.
The speakers: Modded Fostex Fe207E (95dB/w) with FT17H super tweeters (98.5dB/w) Crossover frequency is 10.3kHz, chosen both due to driver specs and because hearing is less sensitive than at 8kHz.
Shopping list:
2x Trends TA10.1, 2x ESP Project 09 active 24dB/oct line level crossover boards, 1x ESP Project 05B power supply with muting.
1RU rack case, toroidal 15-0-15 trafo, assorted bits.
The game plan:
Single fused IEC power connector via switch, feeds 15-0-15 trafo and both stock Trends power supplies inside the box. the two T-amps sit on top connected to cables running through grommets in the lid. Each amp feeds one speaker Hi and low for increased channel separation and plenty of power supply headroom. Volume controls bypassed.
Crossovers: separate ESP P09 boards on either side of the chassis, Stereo 2-way is possible on one board but I may run a 50Hz XO to subs later on. Op-amps are OPA2134 all running unity gain. Deleted 1uF capacitors on the output of the XO because the trends amps have input caps.
Output: Bass&mid effectively straight out. Treble fed via 30uF motor start capacitor in the rack case bypassed with 1uf metal-poly cap. This is purely for DC protection, phase offset above 10k into 8 ohms should be close to zero. To idiot-proof it I'm using 4 pole speakon connectors for the speaker cables. The wires on the speaker terminals on the amps will be routed through the rack case to the connector on the back
XO power supply and muting: Power supply for opamps is linear regulated +/- 15 with power up & loss of AC muting relay drive. 4 separate miniature spdt muting relays connect the XO outputs (and t-amp inputs) to ground via 1uF.
I ordered a bunch of 1000uF low ESR caps as well, Would it be advisable to put these across the Trends power supplies close to the amps?
If so how many uF worth of inrush current would the stock power supply handle?
I have ordered enough caps for 10,000 uF per channel. I may replace the standard Trends supplies with dual linear supplies later on. Batteries aren't an option for me.
Any suggestions?
The speakers: Modded Fostex Fe207E (95dB/w) with FT17H super tweeters (98.5dB/w) Crossover frequency is 10.3kHz, chosen both due to driver specs and because hearing is less sensitive than at 8kHz.
Shopping list:
2x Trends TA10.1, 2x ESP Project 09 active 24dB/oct line level crossover boards, 1x ESP Project 05B power supply with muting.
1RU rack case, toroidal 15-0-15 trafo, assorted bits.
The game plan:
Single fused IEC power connector via switch, feeds 15-0-15 trafo and both stock Trends power supplies inside the box. the two T-amps sit on top connected to cables running through grommets in the lid. Each amp feeds one speaker Hi and low for increased channel separation and plenty of power supply headroom. Volume controls bypassed.
Crossovers: separate ESP P09 boards on either side of the chassis, Stereo 2-way is possible on one board but I may run a 50Hz XO to subs later on. Op-amps are OPA2134 all running unity gain. Deleted 1uF capacitors on the output of the XO because the trends amps have input caps.
Output: Bass&mid effectively straight out. Treble fed via 30uF motor start capacitor in the rack case bypassed with 1uf metal-poly cap. This is purely for DC protection, phase offset above 10k into 8 ohms should be close to zero. To idiot-proof it I'm using 4 pole speakon connectors for the speaker cables. The wires on the speaker terminals on the amps will be routed through the rack case to the connector on the back
XO power supply and muting: Power supply for opamps is linear regulated +/- 15 with power up & loss of AC muting relay drive. 4 separate miniature spdt muting relays connect the XO outputs (and t-amp inputs) to ground via 1uF.
I ordered a bunch of 1000uF low ESR caps as well, Would it be advisable to put these across the Trends power supplies close to the amps?
If so how many uF worth of inrush current would the stock power supply handle?
I have ordered enough caps for 10,000 uF per channel. I may replace the standard Trends supplies with dual linear supplies later on. Batteries aren't an option for me.
Any suggestions?
Hi,
Introducing all those opamps (ESP project 09) in a signal path will surely degrade the sound quality. The best solution is to buy a single Trends TA 10.1 amp.
With a fullrange speaker and a tweeter crossed high, there is little benefit in biamping.
Pour your money for a single 12 v 7-11 Ah gel battery, and buy a charger.
Build a switch so the charger gets disconnected when TA amp is connected and vice versa.
Also, use Dave's single-strand cat-5 based speaker cables.
You'll spend less, get more.
Regards,
Vix
Introducing all those opamps (ESP project 09) in a signal path will surely degrade the sound quality. The best solution is to buy a single Trends TA 10.1 amp.
With a fullrange speaker and a tweeter crossed high, there is little benefit in biamping.
Pour your money for a single 12 v 7-11 Ah gel battery, and buy a charger.
Build a switch so the charger gets disconnected when TA amp is connected and vice versa.
Also, use Dave's single-strand cat-5 based speaker cables.
You'll spend less, get more.
Regards,
Vix
Going rabbit hunting with a Bazooka, are you Mike? 
I have to agree with Dave and Vix. An active crossover you do not need, at least not for this. The whole setup sounds like way overkill. And your likely to kill the music and enjoyment along with it.
The beauty of your Fostex "almost full range" driver is that it will be easy to crossover to the tweeter. You probably only need a single cap on the tweeter. Maybe a cap and a resistor. Keep it Simple.
If you want an active sub later on, that's no big deal. But for a Fostex Fe207E and high crossed tweeter? Easy - passive.
As for the other stuff, 1000uF is no big deal at 12V. I routinely use 2x2200 or more. And yes, you can add them across the stock power supply. I sometimes add 1 or 2x 10,000uF.
The stock PSU with for Trends is OK, but you can do better. The stock unit tends to sound a bit "sour" as my wife said. It's OK, until you hear a better one.
Don't discount a good regulated linear supply, as you planned to build one for your unneeded crossover. A nice 13V regulated will work well. Or find a nice SMPS. I've had good luck with DVE brand "line lumps" and both XP Power and Skynet open frame supplies.
I have to agree with Dave and Vix. An active crossover you do not need, at least not for this. The whole setup sounds like way overkill. And your likely to kill the music and enjoyment along with it.
The beauty of your Fostex "almost full range" driver is that it will be easy to crossover to the tweeter. You probably only need a single cap on the tweeter. Maybe a cap and a resistor. Keep it Simple.
If you want an active sub later on, that's no big deal. But for a Fostex Fe207E and high crossed tweeter? Easy - passive.
As for the other stuff, 1000uF is no big deal at 12V. I routinely use 2x2200 or more. And yes, you can add them across the stock power supply. I sometimes add 1 or 2x 10,000uF.
The stock PSU with for Trends is OK, but you can do better. The stock unit tends to sound a bit "sour" as my wife said. It's OK, until you hear a better one.
Don't discount a good regulated linear supply, as you planned to build one for your unneeded crossover. A nice 13V regulated will work well. Or find a nice SMPS. I've had good luck with DVE brand "line lumps" and both XP Power and Skynet open frame supplies.
Pano,
Do you think that there is any benefit to biamping single driver speakers that have two drivers per side in a dipole arrangement which are provided with separate connectors for each driver. Each driver has it's own enclosed box contained within a single cabinet. Omega Hemp Bi/dipoles are the speakers I'm referring to. It seems to me that I'm getting better channel separation but I've been implementing so many changes to my system recently, that I'm losing track of their effects.
Raj
Do you think that there is any benefit to biamping single driver speakers that have two drivers per side in a dipole arrangement which are provided with separate connectors for each driver. Each driver has it's own enclosed box contained within a single cabinet. Omega Hemp Bi/dipoles are the speakers I'm referring to. It seems to me that I'm getting better channel separation but I've been implementing so many changes to my system recently, that I'm losing track of their effects.
Raj
Does anyone have any other suggestions for an active XO? I really want to try to keep the phase alignment right and I want steep slopes. Unfortunately I have freakishly sensitive high frequency hearing.
Amps arrived yesterday, had some minor issues, resolved already, COEM Audio's customer service is damn good.
Amps arrived yesterday, had some minor issues, resolved already, COEM Audio's customer service is damn good.
Well Mike, I've never heard of someone doing an active 4th order cross to a super tweeter. But you certainly can't be the first.
Why not beg, borrow, buy or hire a Behringer DCX2496 or similar digital crossover? It will give you the flexibility to try almost infinite variations of slopes, filter types, crossover points, phase and time alignment.
Once you find what works, imitate it in an analog circuit. (Easier said than done, of course)
Why not beg, borrow, buy or hire a Behringer DCX2496 or similar digital crossover? It will give you the flexibility to try almost infinite variations of slopes, filter types, crossover points, phase and time alignment.
Once you find what works, imitate it in an analog circuit. (Easier said than done, of course)
Unfortunately no chance of borrowing a Behringer digital XO. Many people use those, they appear to be fairly highly regarded yet they have A-D then D-A then a fairly dodgy looking op-amp output. I don't see how that could be better than a sensible op-amp based filter. I had a good look at Behringer's two analog XOs but they don't appear to be very accurate. Good for the price but not what I'm looking for.
I tried to cancel my parts order for the XOs but didn't make it in time. The parts are in transit.
Since the money is already spent I may as well experiment a bit. It would be nice to run a pair of shadow subs later on so a three way XO is a likely, this is why I bought two XO boards. It looks pretty easy to alter to 2nd or 3rd order. I'll look carefully at the input circuit to the T-amp - I may be able to delete the output buffers. Likewise with my preamp, I may be able to remove the input buffers too.
Any suggestions for making my half-cocked bazooka more sensible?
I tried to cancel my parts order for the XOs but didn't make it in time. The parts are in transit.
Since the money is already spent I may as well experiment a bit. It would be nice to run a pair of shadow subs later on so a three way XO is a likely, this is why I bought two XO boards. It looks pretty easy to alter to 2nd or 3rd order. I'll look carefully at the input circuit to the T-amp - I may be able to delete the output buffers. Likewise with my preamp, I may be able to remove the input buffers too.
Any suggestions for making my half-cocked bazooka more sensible?
Here is a possible layout. I should have ordered a bigger box.
It's a 1RU 19 inch rack case with the "ears" missing, I'm using it the long way so the sides are the front and back. It's well ventilated and I have placed the switched mode supplies and the trends amp boards over the ventilated sections.
One thing that concerns me is running two class D amplifiers in close proximity. They can intermodulate if the clocks aren't synchronised. According to the datasheet for the chip they don;t have a master clock feature. If they start interacting I'll have to shield them from each other. Running two of these from a single power supply would not be a good idea.
After testing theTA10s will be stripped, the boards mounted in the corners and hardwired as power amps with no connectors.
There's easy access to the crossover boards to try different slopes and op-amps. I'll need to swap over some of the TA10 input caps, the amps I got have different caps in them, are the Bennics or the yellow ones with the little triangle logo better?
It's a 1RU 19 inch rack case with the "ears" missing, I'm using it the long way so the sides are the front and back. It's well ventilated and I have placed the switched mode supplies and the trends amp boards over the ventilated sections.
One thing that concerns me is running two class D amplifiers in close proximity. They can intermodulate if the clocks aren't synchronised. According to the datasheet for the chip they don;t have a master clock feature. If they start interacting I'll have to shield them from each other. Running two of these from a single power supply would not be a good idea.
After testing theTA10s will be stripped, the boards mounted in the corners and hardwired as power amps with no connectors.
There's easy access to the crossover boards to try different slopes and op-amps. I'll need to swap over some of the TA10 input caps, the amps I got have different caps in them, are the Bennics or the yellow ones with the little triangle logo better?
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Wow, took a while to find my old thread, I've been putting this together for a LONG time.
The first version is about 50% complete.
I'm running Burr Brown OPA2134 opamps instead of the stocker TL072.
I'll give this one a run like it is. then I'll remove the output buffer on the XO.
Where to start, I found a nice clean 10A continuous 12V external switchmode supply. So that connects through the banana sockets, then to the right hand side of the capacitor board. those caps are all ultra low ESR 1000uF clinch soldered across two tracks of the vero board with a bit of wire laid on top. There are 2 separate banks, one for each amp. Then out the left hand end of the capacitor board to the underside of the trends boards soldered directly onto the standard filter caps. the wire is only 3 inches long. That's going to be a steadier supply than any battery on the floor can ever be.
The unused tracks in the centre of the capacitor board are bussed together and connected to protective earth.
Trends amps have had the input caps taken off the board, header pins have been put in their place on the Tripath chip side of the capacitor positions. the normal input tracks have been grounded.
The little vero-boards have reed relays to mute the XO board and the input caps off the Trends amps. I chose reed relays because glass encapsulated contacts in an inert atmosphere will be as close to a piece of hookup wire as you can get. All unused tracks and parts of tracks on the vero board have been connected to signal ground.
The ESP boards are pretty self explanatory, I used two because I intend to upgrade with some proper subs in future to take some of the load off the fullranger. I havent installed the op-amps yet, or the decoupling caps. I know I've got some axial ceramic caps somewhere, I prefer to solder them directly to the power supply pins of the chip on the underside of the board. I have no idea how much RF the Trends amps will radiate inside the box.
Output connectors are Neutrik Speakon connectors, these are ideal because they are a 4 pole connector so I only have one cable going to each speaker cabinet. Hopefully I'll have this ready to test in a week. I'll take it into work to measure & align the output, 2 amps in the same box might interact and produce some RF funnies on the outputs.
Once I know it works I'll start reducing the number of op-amps to the bare minimum.
Almost time to start hunting Wabbits. <Kaboom!> hahaha
The first version is about 50% complete.
I'm running Burr Brown OPA2134 opamps instead of the stocker TL072.
I'll give this one a run like it is. then I'll remove the output buffer on the XO.
Where to start, I found a nice clean 10A continuous 12V external switchmode supply. So that connects through the banana sockets, then to the right hand side of the capacitor board. those caps are all ultra low ESR 1000uF clinch soldered across two tracks of the vero board with a bit of wire laid on top. There are 2 separate banks, one for each amp. Then out the left hand end of the capacitor board to the underside of the trends boards soldered directly onto the standard filter caps. the wire is only 3 inches long. That's going to be a steadier supply than any battery on the floor can ever be.
The unused tracks in the centre of the capacitor board are bussed together and connected to protective earth.
Trends amps have had the input caps taken off the board, header pins have been put in their place on the Tripath chip side of the capacitor positions. the normal input tracks have been grounded.
The little vero-boards have reed relays to mute the XO board and the input caps off the Trends amps. I chose reed relays because glass encapsulated contacts in an inert atmosphere will be as close to a piece of hookup wire as you can get. All unused tracks and parts of tracks on the vero board have been connected to signal ground.
The ESP boards are pretty self explanatory, I used two because I intend to upgrade with some proper subs in future to take some of the load off the fullranger. I havent installed the op-amps yet, or the decoupling caps. I know I've got some axial ceramic caps somewhere, I prefer to solder them directly to the power supply pins of the chip on the underside of the board. I have no idea how much RF the Trends amps will radiate inside the box.
Output connectors are Neutrik Speakon connectors, these are ideal because they are a 4 pole connector so I only have one cable going to each speaker cabinet. Hopefully I'll have this ready to test in a week. I'll take it into work to measure & align the output, 2 amps in the same box might interact and produce some RF funnies on the outputs.
Once I know it works I'll start reducing the number of op-amps to the bare minimum.
Almost time to start hunting Wabbits. <Kaboom!> hahaha
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