I'm looking at a couple different options for putting together a speaker amp, so of course I had to see what you guys had to offer 😉
When it comes to speakers, I'm pretty clueless (not that I'm much better in other respects ;D). I'm looking at getting a pair of headphones that hook into a transformer box that in turn hooks into the speaker amp, but it recommends using 16ohm outputs. One can use the regular outputs and just expect a decrease in wattage as compared to 8ohms, correct?
Also, being a speaker newb, I'm only just being exposed to amp terms I haven't seen before. The TXO is a chip amp, which I'm just guessing means it uses an IC. It seems like some frown on chip amps...has anyone compared the TXO to other amps?
When it comes to speakers, I'm pretty clueless (not that I'm much better in other respects ;D). I'm looking at getting a pair of headphones that hook into a transformer box that in turn hooks into the speaker amp, but it recommends using 16ohm outputs. One can use the regular outputs and just expect a decrease in wattage as compared to 8ohms, correct?
Also, being a speaker newb, I'm only just being exposed to amp terms I haven't seen before. The TXO is a chip amp, which I'm just guessing means it uses an IC. It seems like some frown on chip amps...has anyone compared the TXO to other amps?
fierce_freak said:
Hello,
I will not answer the subjective question, but as for the technical question the 16ohm load is just fine, and yes you would just see less power output, but the nice thing is since its a bridged configuration it would be like driving a single ended 8 ohm load. So something like 50-60W output could be easily obtained given adequate rails.
Cheers!
Russ
Sounds right,
Russ,
That sounds right, the bridged amp is better than a normal chip 16 ohm loads. A paralleled amp would have almost no power into the 16 ohm.
How far away is service manual for the TX0?
George
Russ,
That sounds right, the bridged amp is better than a normal chip 16 ohm loads. A paralleled amp would have almost no power into the 16 ohm.
How far away is service manual for the TX0?
George
Cool, thanks for the replies, guys. A stereo kit (still has balanced outs?) supplied by a 400va 2x18v (is this high enough?) secondaries traffo would give roughly how much voltage peak-to-peak?
fierce_freak said:
Yes, you get balanced(bridged) output with the stereo kit. The one you want is TXO-2.
18V secondaries will net you something like 25V rails depending on your mains etc. That will allow you something like 45VPP into 16ohms which is around 125W peak.
That trafo should work fine, but if you run 8 ohms loads I just would not push the amp too hard unless you use one per channel in which case you should be fine all the way to 11.
Cheers!
Russ
I would really be interested in actual performance figures? Do you have measurements of the TXO? Something like RMAA figures (including a loopback measurement), favorable with an actual loudspeaker attached.
Unfortunately I don't have the capability of performing such tests. But I would be happy to know the results. 🙂
Cheers!
Russ
Cheers!
Russ
All you'd need is a fairly usable soundcard... Should not be to hard I guess.
It would really be great to see what these modules do compared to other DIY kits.
It would really be great to see what these modules do compared to other DIY kits.
I would like to put together an active system. I like the look of the Twisted Pear Overture power amps. Do you know of suitable active crossovers that are balanced?
I will also need a balanced preamp before the crossover. Which of the Twisted pear preamps would be best?
I have thought about the active filter boards in the group buy section. These are single ended, so there would have to a converter after the crossover before the poweramps. Is this a compromise?
I really like the look of the Overture power amps and want crossovers and a preamp to match as much as possible.
Advice would be very welcome.
I will also need a balanced preamp before the crossover. Which of the Twisted pear preamps would be best?
I have thought about the active filter boards in the group buy section. These are single ended, so there would have to a converter after the crossover before the poweramps. Is this a compromise?
I really like the look of the Overture power amps and want crossovers and a preamp to match as much as possible.
Advice would be very welcome.
Texas Instruments has an excellent tool for designing active crossovers even fully differential types. 🙂
I don't know of any out of the box fully differential DIY xover solutions, sorry. Perhaps I will try one some day.
Still even using single ended xovers would not be any issue at all. The TXD performance is great even with single ended input. Simply connect -in to GND.
Cheers!
Russ
I don't know of any out of the box fully differential DIY xover solutions, sorry. Perhaps I will try one some day.
Still even using single ended xovers would not be any issue at all. The TXD performance is great even with single ended input. Simply connect -in to GND.
Cheers!
Russ
Thanks for that.
I read that the Overture performs so much better in fully balanced mode. I'm guessing that preamps would too.
A good starting point for me would be A pair of mono Overtures fed by a balanced pre. Which of the Twisted Pear preamps would suit best?
cheers
Aidan
I read that the Overture performs so much better in fully balanced mode. I'm guessing that preamps would too.
A good starting point for me would be A pair of mono Overtures fed by a balanced pre. Which of the Twisted Pear preamps would suit best?
cheers
Aidan
chalkandtalk said:
Well you have some options.
1) Use a balanced source like the Opus or the COD DACs. Follow that with a Joshua tree, and you will not need any other preamp. See my writeup here: http://www.diyaudio.com/forums/showthread.php?postid=1409978#post1409978
2) Just use the TPMs (a high quality LM3886 amp in its own right) in single ended mode. In which case you could also simply use a Joshua Tree attenuator in front of the amp, or use a Kookaburra if you want an active SE solution.
The Joshua Tree works very well in front of either the balanced or single ended amps.
Cheers!
Russ
comments on chassis layout?
Before I drill too many holes, I thought I'd invite comments/suggestions on my anticipated amp floorplan. It's a 4 channel TXO-2 that can be switched to two channels bi-amped. In 4 channel mode it will contribute for DD/Dts 5.1 sources (alongside with my first stereo TXO-2). In bi-amp mode it will drive 15" woofers (<= 180 Hz only).
Each channel is a TPM pair flanking a center-mounted TXD on custom brackets (to keep interconnects short). The three-board asselbly is supported entirely by the heat sink, and is positioned with the hot-spot of the 3886 nearly centered in the radiating field. The sides of the 3U rack box are chopped back 1" to expose the heatsink vanes. Balanced inputs and their grounds will switch via a modified Darwin board and input wiring will run near the top of the case. Outputs from 2 of the 4 power modules (the 'top two' in the photo) will be switched using two (super-gnarly!) 12 V. power relays with silver contacts. I chose them partly because of the convenient mounts moulded into the bases. Relay control wiring will run from the front panel backwards between the transformers and power supplies. Transformers are 22V - using 25 V, my other TXO-2 driving only mids & tweets (>= 6 ohms) sheds plenty of heat. These heatsinks are 50% larger - I'll wait to see if they need to be painted flat black like the ones in my other TXO-2.
I'm having a great time with this... Thanks to Russ and Brian for doing all of the hard work so that beginners like me can play DIYer!
All suggestions much appreciated!
Frank in Minneapolis
Before I drill too many holes, I thought I'd invite comments/suggestions on my anticipated amp floorplan. It's a 4 channel TXO-2 that can be switched to two channels bi-amped. In 4 channel mode it will contribute for DD/Dts 5.1 sources (alongside with my first stereo TXO-2). In bi-amp mode it will drive 15" woofers (<= 180 Hz only).
Each channel is a TPM pair flanking a center-mounted TXD on custom brackets (to keep interconnects short). The three-board asselbly is supported entirely by the heat sink, and is positioned with the hot-spot of the 3886 nearly centered in the radiating field. The sides of the 3U rack box are chopped back 1" to expose the heatsink vanes. Balanced inputs and their grounds will switch via a modified Darwin board and input wiring will run near the top of the case. Outputs from 2 of the 4 power modules (the 'top two' in the photo) will be switched using two (super-gnarly!) 12 V. power relays with silver contacts. I chose them partly because of the convenient mounts moulded into the bases. Relay control wiring will run from the front panel backwards between the transformers and power supplies. Transformers are 22V - using 25 V, my other TXO-2 driving only mids & tweets (>= 6 ohms) sheds plenty of heat. These heatsinks are 50% larger - I'll wait to see if they need to be painted flat black like the ones in my other TXO-2.
I'm having a great time with this... Thanks to Russ and Brian for doing all of the hard work so that beginners like me can play DIYer!
All suggestions much appreciated!
Frank in Minneapolis
Attachments
Great job!
Hi Frank,
Incredible layout work. I love it.
One word of warning. While it may work just fine (it has worked for me) be very careful when testing your parallel TXO-2s as some have had issues with instability when trying that configuration.
There may be some thing we can do to make it work if you have issues. So please contact me privately if you notice any problems in running that configuration.
It is a very well thought out implementation very good work.
Cheers!
Russ
Hi Frank,
Incredible layout work. I love it.
One word of warning. While it may work just fine (it has worked for me) be very careful when testing your parallel TXO-2s as some have had issues with instability when trying that configuration.
There may be some thing we can do to make it work if you have issues. So please contact me privately if you notice any problems in running that configuration.
It is a very well thought out implementation very good work.
Cheers!
Russ
Symmetrical Amp Udpate
I have really enjoyed my Twisted X Overture design, and one of its best features is relative simplicity. one of the more tricky aspects is scaling, because the power modules are amplifiers in and of themselves, so you end up with multiple nested feedback loops. This can be difficult to control.
My next evolution of this amplifier changes the output configuration blocks moving away from the chip amp, and toward a very simple CFP gain block (discrete). The gain in the CFP is just enough to allow full output (around 12-18db). The overall gain is still controlled by the core symmetric amp (what is now the TXD) and can be whatever you need and the devices can support.
I will post more detail later, but it should be fun, especially for those of us who crave more power. 🙂
Cheers!
Russ
I have really enjoyed my Twisted X Overture design, and one of its best features is relative simplicity. one of the more tricky aspects is scaling, because the power modules are amplifiers in and of themselves, so you end up with multiple nested feedback loops. This can be difficult to control.
My next evolution of this amplifier changes the output configuration blocks moving away from the chip amp, and toward a very simple CFP gain block (discrete). The gain in the CFP is just enough to allow full output (around 12-18db). The overall gain is still controlled by the core symmetric amp (what is now the TXD) and can be whatever you need and the devices can support.
I will post more detail later, but it should be fun, especially for those of us who crave more power. 🙂
Cheers!
Russ
Russ,
I have a chipamp gainclone that i am using with an Opus module. Excellent performace but recently i have been looking at your TPM modules for more oomph and use in balanced mode for better performance. I want to build a TXO-4
Trouble is your TXD is out of stock for quite a while now I've noticed.
Is that intentional, are you designing something new? If not what could i use as an alternative?
Second question is can i use your OPUS DAC to replace my CDP's DAC (it is the good old CD723) ? If i go for the more powerful TXO-4 i would love to try the Buffalo DAC
Thanks
Evan
I have a chipamp gainclone that i am using with an Opus module. Excellent performace but recently i have been looking at your TPM modules for more oomph and use in balanced mode for better performance. I want to build a TXO-4
Trouble is your TXD is out of stock for quite a while now I've noticed.
Is that intentional, are you designing something new? If not what could i use as an alternative?
Second question is can i use your OPUS DAC to replace my CDP's DAC (it is the good old CD723) ? If i go for the more powerful TXO-4 i would love to try the Buffalo DAC
Thanks
Evan
Yes there is something new in the works. 🙂
The TXO-2 configuration works very well, but we no longer recommend or sell kits for the TXO-4 configuration because it is known to be unstable.
The new amp will have discrete components, but not be difficult to build. It will scale much better without the need to parallel opamps.
Cheers!
Russ
The TXO-2 configuration works very well, but we no longer recommend or sell kits for the TXO-4 configuration because it is known to be unstable.
The new amp will have discrete components, but not be difficult to build. It will scale much better without the need to parallel opamps.
Cheers!
Russ
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