We would be paralleling two of our TPM-OPA549 (or TPM-LM3886)modules, each containing its own feedback loop and optional servo. It would really be a bridged/paralleled circuit.
So, each channel, if paralleled, would consist of a TXD module (symmetric driver), with the + output driving two paralleled TPM-OPA549 modules, and the - output driving two paralleled TPM-OPA549 modules, for a total of 4 chips per channel.
The kit will consist of just two per channel, but you can add as many in parallel as you like, and they will be available seperately. In fact, each TPM module could be used as a simple SE amp channel by itself.
So, each channel, if paralleled, would consist of a TXD module (symmetric driver), with the + output driving two paralleled TPM-OPA549 modules, and the - output driving two paralleled TPM-OPA549 modules, for a total of 4 chips per channel.
The kit will consist of just two per channel, but you can add as many in parallel as you like, and they will be available seperately. In fact, each TPM module could be used as a simple SE amp channel by itself.
Re: TXS parallel
Yes the datasheet gives a simple way to parallel the OPA549.
There are two ways to do it with the TPM-OPA549 PCB. You can do it by paralleling two identical circuits using an output resistor on each.
Or, you can set one module up for unity gain and take the output of the actual "Master" module as the input for the follower still using the output resistor.
The second approach is a bit simpler to wire, but the two circuits will not be as well matched, and it may not sound as good as using two identical circuits.
psroczka said:
Yes the datasheet gives a simple way to parallel the OPA549.
There are two ways to do it with the TPM-OPA549 PCB. You can do it by paralleling two identical circuits using an output resistor on each.
Or, you can set one module up for unity gain and take the output of the actual "Master" module as the input for the follower still using the output resistor.
The second approach is a bit simpler to wire, but the two circuits will not be as well matched, and it may not sound as good as using two identical circuits.
TXO-2 version done working 
OK here is a simple 2 TPM-LM3886 X amp. Not merely bridged.
Here are some pictures which may help visualize what is possible, next I will add four more TPM-Lm3886 modules in parallel with the existing ones, this will easily give me around 250W of power into 4ohms.
Cheers!
Russ
Front...
OK here is a simple 2 TPM-LM3886 X amp. Not merely bridged.
Here are some pictures which may help visualize what is possible, next I will add four more TPM-Lm3886 modules in parallel with the existing ones, this will easily give me around 250W of power into 4ohms.
Cheers!
Russ
Front...
Attachments
There is still a lot of case wiring cleanup to do, but I am very pleased with the result so far. < 10mv offset.
Each TPM module has a DC nulling servo to keep the idle current under control and generally keep the amp happy. These can easily be omitted all together or replaced with a feedback cap (place on PCB for this) which will make the amp unity gain at DC. For me the servo is staying.
It sounds as good as anything I have heard with a national chip in it.
Cheers!
Russ
Each TPM module has a DC nulling servo to keep the idle current under control and generally keep the amp happy.
These can easily be omitted all together or replaced with a feedback cap (place on PCB for this) which will make the amp unity gain at DC. For me the servo is staying. It sounds as good as anything I have heard with a national chip in it.
Cheers!
Russ
Awesome!
Looking good. I hope to build one of these once boards are available. How much do you estimate this will output into 6 - 8 ohms with +/- 30 volt rails?
I have gathered most parts, picked up a pair of 400 va +/- 20 volt trannies. Not waiting on boards, still cleaning up a couple other items. This is something I hope to build sometime early next year. Is that close to your plan commercial release?
Wish I had left the family at Opry Mills one night and tried to swing by and listen last month.. Did not happen, problem with getting them out of the car in the 20 degree weather.
George
Looking good. I hope to build one of these once boards are available. How much do you estimate this will output into 6 - 8 ohms with +/- 30 volt rails?
I have gathered most parts, picked up a pair of 400 va +/- 20 volt trannies. Not waiting on boards, still cleaning up a couple other items. This is something I hope to build sometime early next year. Is that close to your plan commercial release?
Wish I had left the family at Opry Mills one night and tried to swing by and listen last month.. Did not happen, problem with getting them out of the car in the 20 degree weather.
George
Hi George,
Thanks.
No problem. Family comes first. The invite is always open for you.
I will be making a PCB order here very soon (before the holidays). Brian already has a good jump on the parts.
I hate talking about how my own amplifiers sound, but I can't really find any faults in this one. It is quiet when it should be, and loud when you want it to be.
As for output power you could expect something like (of the cuff) 80W into 8ohms from those rails. I am using 600VA 20V secondaries get roughly 34V rails (perfect for when I go parallel). But I will be putting in some 500VA 25V secondaries here soon (better for the 8ohm loads).
Cheers!
Russ
Thanks.
No problem. Family comes first.
The invite is always open for you.I will be making a PCB order here very soon (before the holidays). Brian already has a good jump on the parts.
I hate talking about how my own amplifiers sound, but I can't really find any faults in this one. It is quiet when it should be, and loud when you want it to be.
As for output power you could expect something like (of the cuff) 80W into 8ohms from those rails. I am using 600VA 20V secondaries get roughly 34V rails (perfect for when I go parallel). But I will be putting in some 500VA 25V secondaries here soon (better for the 8ohm loads).
Cheers!
Russ
Here's a pic of my prototype TXO under construction (monoblocks).
An externally hosted image should be here but it was not working when we last tested it.
erikdebier said:
Hi Erik,
Its very hard to make a direct comparison, and I believe Brian and I are the only people to have heard the actual TXO with TXD and TPM modules. But we are certainly not impartial and any review either of us gave would be biased.
That said, here is my biased review. First it is much more powerful than RevC especially into an 8 ohm load as it swing nearly double the voltage. Also you can parallel output PCBs (TPM-LM3886) to get 250W+ power into 4 ohms easy. So for starters it is a much better amp choice for large power hungry speakers. That said, it also lends itself to sensitive speakers because the noise floor is incredibly low especially with balanced input.
Example, I have been borrowing a pair of Jordan single driver speakers that are very sensitive, with TXO silence is black, with my RevC there is just a hint (ear to he cone) of EMI noise and clicks when things like the fridge turn on. Not enough to be objectionable mind you. The RevC is solid, its just that's the difference between balanced input that rejects common mode noise.
Thats about the only direct comparison I will make, but I can say a few more things about the TXO. One of the benefits of the Symmetric nature of the amp (it is not simply bridged) is that because things like crossover distortion, which is always present in any chipamp, appears to the driver in opposing phase, thus common mode, and canceled out. So the TXO has lower crossover distortion. Also, it has incredible dynamic range because the performance of the amp is dominated by the THS4131 which has a great slew rate. The THS4131 is essentially the "soul" of the amp. The LM3886 is really just follower with gain.
In short, the 55W RevC is an excellent choice if you only plan on using single ended gear. I still listen to it regularly.
The TXO is my favorite, of course, and it has proven itself able to drive a much more varied array of speakers. Its character is different, I would say better, but it is also more expensive to make, and not as simple. You pay the price of complexity for quality. The RevC is unrivaled in terms of sound quality for price. TXO is indeed better, but at the expense of cost and complexity.
I hope that helps. Also Mauro is to be acknowledged and thanked for has invaluable contribution to the forum and to my personal knowledge. I rely on him for input often and he is a reliable friend. He designed an incredible amplifier topology and was very unselfish in sharing it.
Cheers!
Russ
Latest News
Just giving this thread a bump as I would like to hear what the latest is at Twisted Pear. Have the new boards arrived and kit prices finalized?
Russ/Brian; How do you compare the sound of the new driver module as a preamp to the X-BOSOZ. Do you think that you will continue to offer both in the future? Or does one consistently outperform the other?
Regards,
Jason
Just giving this thread a bump as I would like to hear what the latest is at Twisted Pear. Have the new boards arrived and kit prices finalized?
Russ/Brian; How do you compare the sound of the new driver module as a preamp to the X-BOSOZ. Do you think that you will continue to offer both in the future? Or does one consistently outperform the other?
Regards,
Jason
Re: Latest News
HI Jason,
Here is the latest. After a lot of testing a new power supply was designed and I just finished it today. It was worth the work. With that behind me now I will making an order for PCBs Monday. So look for these soon!.
XBOSOZ is a very cool preamp, but its PSRR is not nearly as good as that of the TXD. So with the XBOSOZ and attenuator/pot on input you will always get a bit of a hiss unless you have a very quiet PS. With the attenuator on output XBOSOZ is much better, but also has higher output impedance.
The TXD is much easier to build, and does not require the DC blocking caps that the XBOSOZ does. In a word, it is more practical.
TXD fills an important role in our lineup, that of balanced driver, SE/BAL converter, and the key component to our "Twisted X" amps.
Cheers!
Russ
jasonb84 said:
HI Jason,
Here is the latest. After a lot of testing a new power supply was designed and I just finished it today. It was worth the work.
With that behind me now I will making an order for PCBs Monday. So look for these soon!.XBOSOZ is a very cool preamp, but its PSRR is not nearly as good as that of the TXD. So with the XBOSOZ and attenuator/pot on input you will always get a bit of a hiss unless you have a very quiet PS. With the attenuator on output XBOSOZ is much better, but also has higher output impedance.
The TXD is much easier to build, and does not require the DC blocking caps that the XBOSOZ does. In a word, it is more practical.
TXD fills an important role in our lineup, that of balanced driver, SE/BAL converter, and the key component to our "Twisted X" amps.
Cheers!
Russ
Brian or Russ,
Beings I can't seem to get an email response from your website, what is the expectations on delivery of the lpm3886 kits pre-ordered and pre-paid? I was surprised that even though I received acknowledgement from paypal, nothing from your site for payment. I want to make sure it was received.
andy
Beings I can't seem to get an email response from your website, what is the expectations on delivery of the lpm3886 kits pre-ordered and pre-paid? I was surprised that even though I received acknowledgement from paypal, nothing from your site for payment. I want to make sure it was received.
andy
Great!
I am really sort of taking a chance on these for my setup. Not that the amps aren't fantastic, but they will be driving the Hawthorne Audio 15" coaxial Open Baffle in a Home Theater that doubles as a multi channel listening environment. They are sensitive at about 96db. I am hoping to do five channels with the basic amp modules and two Open baffle woofers with the TXO's bridged.
thanks!
andy
I am really sort of taking a chance on these for my setup. Not that the amps aren't fantastic, but they will be driving the Hawthorne Audio 15" coaxial Open Baffle in a Home Theater that doubles as a multi channel listening environment. They are sensitive at about 96db. I am hoping to do five channels with the basic amp modules and two Open baffle woofers with the TXO's bridged.
thanks!
andy
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