Hi AKSA do you have a recommended/standards spec list for a Tortech Tx suitable for Alpha BBB?
There doesn’t seem to be any appropriate trannies in stock so I plan to submit a custom quote - I’m thinking: for a dual mono setup one for each channel, toroidal, 600 VA, 2x32Vac secondaries, winding screen
Thanks AKSA
Hi Aive,
You will find Tortech may charge you $115 for a custom transformer, over and above the standard price........
I would suggest using a 500VA 30-0-30 dual secondaries. At full tilt you would have about 34Vdc after the power supply and that is enough. Most mains in Oz are over voltage; 245Vac is the norm at present. If you use the active rectifier you will gain 1.5V over a normal bridge.
The BB is a very large amplifier with heavy thermal stresses. Take a deep breath before you commence; it's difficult, an advanced project.
Hugh
You will find Tortech may charge you $115 for a custom transformer, over and above the standard price........
I would suggest using a 500VA 30-0-30 dual secondaries. At full tilt you would have about 34Vdc after the power supply and that is enough. Most mains in Oz are over voltage; 245Vac is the norm at present. If you use the active rectifier you will gain 1.5V over a normal bridge.
The BB is a very large amplifier with heavy thermal stresses. Take a deep breath before you commence; it's difficult, an advanced project.
Hugh
aive,
I also in the past bought Antek transformers, Which are very good transformers
but when their shipping charges became outrageous i found that RS had this line of transformers which i have found to work without any issues, and free shipping to boot. To date i have not built the Alpha BB as the Alpha 20 more than meets my needs and have a Swag of other builds still to be started but have not felt the need to so. Good luck with your Alpha BB build.
Steve.
I also in the past bought Antek transformers, Which are very good transformers
but when their shipping charges became outrageous i found that RS had this line of transformers which i have found to work without any issues, and free shipping to boot. To date i have not built the Alpha BB as the Alpha 20 more than meets my needs and have a Swag of other builds still to be started but have not felt the need to so. Good luck with your Alpha BB build.
Steve.
I just received my boards today (SLB GB came through very quickly from your notice, thanks XRK!) and have started working on my BoM. They look even better in person!
I've got everything put together so far for my build, but unfortunately Mouser is out of stock until late August on the IXFH74N20P devices. I was wondering if there's anything in the datasheet of the IXTH76N25T that would preclude its substitution. I plan to pair it with the IXTK90P10P and the only major difference I see is a higher transconductance than the 74N20P, about double that of the paired PMOS.
Reading back I saw to look at Ciss and RthJC, both of which are in the same ballpark as the original NMOS. RDSon is about 25% higher and Vth_min is 3V versus the original's 2.5V, however. I wouldn't think this would make much of a difference.
I've got everything put together so far for my build, but unfortunately Mouser is out of stock until late August on the IXFH74N20P devices. I was wondering if there's anything in the datasheet of the IXTH76N25T that would preclude its substitution. I plan to pair it with the IXTK90P10P and the only major difference I see is a higher transconductance than the 74N20P, about double that of the paired PMOS.
Reading back I saw to look at Ciss and RthJC, both of which are in the same ballpark as the original NMOS. RDSon is about 25% higher and Vth_min is 3V versus the original's 2.5V, however. I wouldn't think this would make much of a difference.
You are welcome. Glad to hear that these boards are getting to their destinations quickly via USPS (at least in US). So it was a surprise for me to hear that Schiit just fired USPS as their primary shipper due to lack of good service.
I have been itching to build the ABBB, but I have been consumed in the past week dealing with putting out a raging fire at work. Hopefully things calm down enough this weekend for me to start slinging solder again.
Greetings to all!
I have some questions related to ABBB ... if possible ???
-Power supply with transformer 500VA 36-0-36V, is in tolerance?
-It is possible to down grade the expected maximum power by halving the supply voltage, 18-0-18V, and then use
passive heat sinks, maintaining the timbre characteristics, powerful bass; if it can be done, will other changes to the circuit be necessary?
-Changing point of work [from class A to class AB] is possible?
if yes, with which interventions?
Thanking you in advance to those who wanted to answer my questions, I greet you all.
Ciao
I have some questions related to ABBB ... if possible ???
-Power supply with transformer 500VA 36-0-36V, is in tolerance?
-It is possible to down grade the expected maximum power by halving the supply voltage, 18-0-18V, and then use
passive heat sinks, maintaining the timbre characteristics, powerful bass; if it can be done, will other changes to the circuit be necessary?
-Changing point of work [from class A to class AB] is possible?
if yes, with which interventions?
Thanking you in advance to those who wanted to answer my questions, I greet you all.
Ciao
Hello Mleod,
A dual secondary transformer 0-32v, 0-32v is needed for the ABBB amplifier.
A center tapped transformer such as your 36v-0-36v will not work for this application.
Cheers
Also, if you are going to use 18V trafo, just make the Alpha 20. It’s the same amp - really, just designed for lower power. Maybe pair it with an SLB if you want the same power-supply as ABBB. Vunce has done this and it works very well from what I hear. If you want the SSR protection circuit, that will be available separately soon.
Alpha 20’s are available here:
ALPHA 20 Class A Amplifier PCB | Etsy
Alpha 20’s are available here:
ALPHA 20 Class A Amplifier PCB | Etsy
Hi, BB BOM specifies IXFH94N30P3 but I went looking for something with a TO-264 package to match the P-channel.
Would IXFK170N20T/IXFX170N20T be appropriate replacement? It has very similar transconductance and is available in TO-264. Ciss is very different to the P-channel though, but that is also the case with the IXFH94N30P3.
Thanks
Greetings to all!
I would like to re-propose my question regarding the voltage of the power supply transformer: the voltage of about 0-35V can work equally with respect to the required 0-32V voltage.
The configuration of the power supplies is not a problem, I have already modified in the past the configuration of the outputs of transformers ... I thank in advance for the attention, I greet you all cordially.
Mleod
I would like to re-propose my question regarding the voltage of the power supply transformer: the voltage of about 0-35V can work equally with respect to the required 0-32V voltage.
The configuration of the power supplies is not a problem, I have already modified in the past the configuration of the outputs of transformers ... I thank in advance for the attention, I greet you all cordially.
Mleod
Hi Mleod,
Which amp are you planning on building? The ABBB is an integrated amp and PSU, and the PSU requires two separate secondary windings to generate the dual rail voltages. A split secondary with common 0v won’t work on the ABBB. However, with the Alpha 20, you can use your own PSU to produce the dual rails form a center tap trafo.
Which amp are you planning on building? The ABBB is an integrated amp and PSU, and the PSU requires two separate secondary windings to generate the dual rail voltages. A split secondary with common 0v won’t work on the ABBB. However, with the Alpha 20, you can use your own PSU to produce the dual rails form a center tap trafo.
Hi XRK!
Thank you. I would be ABBB oriented, in the past you had highlighted the ability of a consistent bass. Having an OB set, this feature would suit me: they are fast and transparent but the powerful depth would need any help. Basically I would like to understand if 35V are too many for this circuit, against the expected 32V, or if they can be tolerated, we are about 10 percent more than the desired voltage, but I can't realize what consequences the ABBB circuit can have. As I said above, 36-0-36 vs 36-0 x2, it is not a problem, I could intervene in the transformers, as I have done in the past.
The interest in ALPHA20 would be relative, I'm using a 20W JLH and frankly it's not bad, except for pure exercise without a specific purpose; the ABBB would make sense as I said before, for a better presence of bass. I hope I was understandable, thanking, greeting.
Mleod
Thank you. I would be ABBB oriented, in the past you had highlighted the ability of a consistent bass. Having an OB set, this feature would suit me: they are fast and transparent but the powerful depth would need any help. Basically I would like to understand if 35V are too many for this circuit, against the expected 32V, or if they can be tolerated, we are about 10 percent more than the desired voltage, but I can't realize what consequences the ABBB circuit can have. As I said above, 36-0-36 vs 36-0 x2, it is not a problem, I could intervene in the transformers, as I have done in the past.
The interest in ALPHA20 would be relative, I'm using a 20W JLH and frankly it's not bad, except for pure exercise without a specific purpose; the ABBB would make sense as I said before, for a better presence of bass. I hope I was understandable, thanking, greeting.
Mleod
HI AKSA!
Thank you. I understand that the power supply value of 32V is the ideal one and I can only adhere to the indications. But in the distant past 10 percent of tolerance was very common thing. Now in the specific, I judge the circuitry adopted as truly contemporary, both in the components and in the solutions and I cannot, given the adopted automatisms, evaluate the problems resulting from a marginal but basic variation like the one I proposed. Thanks for the directions. Greetings.
Mleod
Thank you. I understand that the power supply value of 32V is the ideal one and I can only adhere to the indications. But in the distant past 10 percent of tolerance was very common thing. Now in the specific, I judge the circuitry adopted as truly contemporary, both in the components and in the solutions and I cannot, given the adopted automatisms, evaluate the problems resulting from a marginal but basic variation like the one I proposed. Thanks for the directions. Greetings.
Mleod
36v trafo gives 50.8vdc rectified assuming no load. Depending on the capacity of your trafo... When we use a 400VA 32v trafo, the voltage sag is about 5v, and additional 3v drop due to cap Mx, we can subtract about 8v from 50.8v and we get bout 42v to 43v. 43v x 2 x 3A = 258W. Assuming you use one CPU cooler per MOSFET at 130w each, that works fine as I am dissipating 160w on my other amp. But the DC set-points may be far enough away from nominal that a whole rejiggering of resistors might be needed to ensure proper operation and stability. You would be off into uncharted territory relative to the ABBB verification build going on right now with +/-35vdc.