If anyone needs LuFo PCBs as described here:
LuFo Amp - 39w SE Class A from 28v Rail
You can order your own from the Gerbers provided or put your name here in the GB interest list and I will order them and make them available in my shop for a nominal cost.
Boards sold as pairs in a panel.
Please add your name, number of boards (pair), and country below.
For example:
JohnAmpBuilder / 1 pair / USA
LuFo Amp - 39w SE Class A from 28v Rail
You can order your own from the Gerbers provided or put your name here in the GB interest list and I will order them and make them available in my shop for a nominal cost.
Boards sold as pairs in a panel.
Please add your name, number of boards (pair), and country below.
For example:
JohnAmpBuilder / 1 pair / USA
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Hi xrk
Firstly, kudos for contributing a further innovative project
(I continue to be snowed under, designing a complex makeover for my house) … in the few in-between times, I’m deciding what project to put in the post-design pipeline -
the PCBs
I’m guessing they’ll be ordered after JPS64 adds the pot to adjust the LU1014’s Vgs? and with provision for a cap ( ~10 uF) to the wiper?
(and unlikely/ possibly if there were any further yet-to-be identified refinements)
Are they are/ will be compliant with the store’s UMS cases?
What’s the possibility that the GB could optionally include
either
- the Lender daughter board (in the works)
- or a M2X format front end?
You’ve previously mentioned the Lender and the 2/3 others which can definitely provide enough vpp output. While all are ~ class A so ~ broadly similar, the one with the particular sound flavour which most appeals to me is the Haiku. I understand it can’t provide 100% of the ideal input.
But, keeping it simple, ie without modifications, a pair of Haiku
- Balanced
- Biased up a little
Approx ~ vpp would that be likely to output, and what ballpark output watts would we get? (within 10 wpc would be fine)
My thinking: if using (say) the Lender we can get to 100 watts, while a pair of biased-up Haiku would limit that (for argument's sake) to an output of 70 - it’s still a healthy number. And the drop in potential maximum dB/ headroom would only be around 1 dB
And if as you did, we use a generously specced 600 VA choke, the other arguably more important quality of ability to handle a succession of low bass transients - I’d think should still be healthy. Leading to …
final thought. at one point (one of the related threads) you said that a/ the choke might be in a GB.
In this amp, a good choke seems at least as important to the ability to handle dynamics, certainly more unique to the overall project, than the ideal input-side volts. Yes, they’re heavy-ish. But your description of the specially specced unit you got - sounds like it’s a better option than one from microwave or a Hammond. Seems a logical/ fundamental/ companion GB
HTH
Firstly, kudos for contributing a further innovative project
(I continue to be snowed under, designing a complex makeover for my house) … in the few in-between times, I’m deciding what project to put in the post-design pipeline -
the PCBs
I’m guessing they’ll be ordered after JPS64 adds the pot to adjust the LU1014’s Vgs? and with provision for a cap ( ~10 uF) to the wiper?
(and unlikely/ possibly if there were any further yet-to-be identified refinements)
Are they are/ will be compliant with the store’s UMS cases?
What’s the possibility that the GB could optionally include
either
- the Lender daughter board (in the works)
- or a M2X format front end?
You’ve previously mentioned the Lender and the 2/3 others which can definitely provide enough vpp output. While all are ~ class A so ~ broadly similar, the one with the particular sound flavour which most appeals to me is the Haiku. I understand it can’t provide 100% of the ideal input.
But, keeping it simple, ie without modifications, a pair of Haiku
- Balanced
- Biased up a little
Approx ~ vpp would that be likely to output, and what ballpark output watts would we get? (within 10 wpc would be fine)
My thinking: if using (say) the Lender we can get to 100 watts, while a pair of biased-up Haiku would limit that (for argument's sake) to an output of 70 - it’s still a healthy number. And the drop in potential maximum dB/ headroom would only be around 1 dB
And if as you did, we use a generously specced 600 VA choke, the other arguably more important quality of ability to handle a succession of low bass transients - I’d think should still be healthy. Leading to …
final thought. at one point (one of the related threads) you said that a/ the choke might be in a GB.
In this amp, a good choke seems at least as important to the ability to handle dynamics, certainly more unique to the overall project, than the ideal input-side volts. Yes, they’re heavy-ish. But your description of the specially specced unit you got - sounds like it’s a better option than one from microwave or a Hammond. Seems a logical/ fundamental/ companion GB
HTH
Hi Otto,
I also personally like the sound of the Hakuin perhaps the most of all the preamps. I will post the Aksa Lender and OPA454 front ends. They also need some minor tweaking. The Aksa Lender actually had a major revision after Vunce found out that the DCDC converter we were using was not able to make 55v. We had to go with a different chip completely. There was actually a lot of behind the scenes development work on those front end boards.
So we need to wait for JPS64 to finalize the layouts. They take quite a lot of time and I am grateful to JPS64 for all that he does for us.
The Hakuin topology could be used as a conventional preamp to drive the OPA454 and that will impart it with the flavor of SE Class A front end.
However, keep in mind that the SuSyLu and LuFo itself has that built in to the output stage already.
The custom inductor is certainly a critical and enabling piece of tech for this amp. I am not sure I want to deal with shipping a pair of 11lb chunks of iron. Especially overseas. Let me think about it. The other issue is that if I make a commercial amp out of this, the inductor is the key ingredient.
There might be a HV version of the Hakuin based on all BJT parts with a crazy 250v rail to allow +/-80Vpp.
Good to see a little more interest in the LuFo PCBs.
I also personally like the sound of the Hakuin perhaps the most of all the preamps. I will post the Aksa Lender and OPA454 front ends. They also need some minor tweaking. The Aksa Lender actually had a major revision after Vunce found out that the DCDC converter we were using was not able to make 55v. We had to go with a different chip completely. There was actually a lot of behind the scenes development work on those front end boards.
So we need to wait for JPS64 to finalize the layouts. They take quite a lot of time and I am grateful to JPS64 for all that he does for us.
The Hakuin topology could be used as a conventional preamp to drive the OPA454 and that will impart it with the flavor of SE Class A front end.
However, keep in mind that the SuSyLu and LuFo itself has that built in to the output stage already.
The custom inductor is certainly a critical and enabling piece of tech for this amp. I am not sure I want to deal with shipping a pair of 11lb chunks of iron. Especially overseas. Let me think about it. The other issue is that if I make a commercial amp out of this, the inductor is the key ingredient.
There might be a HV version of the Hakuin based on all BJT parts with a crazy 250v rail to allow +/-80Vpp.
Good to see a little more interest in the LuFo PCBs.
Boards are 250mm long. You can see the dimensions in the Gerber zip file or look at the PCBA stuffing diagram. There is a 10mm edge distance that needs to be added from the bolt to the edge.
I will also offer the front end board but so far only the OPA454 had been tested and the Aksa Lender one needs to be tested. There is a minor layout error that needs to be corrected in the PSU sub board and that can be released. I do not plan to offer it ready to run. Just not enough interest.
The latest schematics, BOM, and Gerber files are here:
LuFo Amp - 39w SE Class A from 28v Rail
I will also offer the front end board but so far only the OPA454 had been tested and the Aksa Lender one needs to be tested. There is a minor layout error that needs to be corrected in the PSU sub board and that can be released. I do not plan to offer it ready to run. Just not enough interest.
The latest schematics, BOM, and Gerber files are here:
LuFo Amp - 39w SE Class A from 28v Rail
Plott / 1 pair / Austria
Kokanee / 2 pair / Canada
spiggs / 2 pair / USA
pfdavid / 2 pair /USA
jonboylaw / 1 pair / UK. (interested in Chokes as well if shipping reasonable).
dBel84 / 1 pair / USA
Skip Pack / 3 pair/ USA (choke interest)
VeightTripleDivision / 1 pair / Latvia (choke curiosity, no idea how affordable it is tho)
Kokanee / 2 pair / Canada
spiggs / 2 pair / USA
pfdavid / 2 pair /USA
jonboylaw / 1 pair / UK. (interested in Chokes as well if shipping reasonable).
dBel84 / 1 pair / USA
Skip Pack / 3 pair/ USA (choke interest)
VeightTripleDivision / 1 pair / Latvia (choke curiosity, no idea how affordable it is tho)
Hi Folks,
You can place your pre-order for the LuFo boards in my shop now. Boards are sold per pair in a panel for $45. 1.6mm thick x 2oz copper with HASL finish, green solder mask.
Pre-order Lufo Class A Amp PCB | Etsy
Regarding the custom choke. I have to do some research. These are heavy items and not easy or inexpensive to ship so I am not sure if I want to burden myself with the headaches that go with it.
I expect to be shipping you the boards in 2-3 weeks.
You can place your pre-order for the LuFo boards in my shop now. Boards are sold per pair in a panel for $45. 1.6mm thick x 2oz copper with HASL finish, green solder mask.
Pre-order Lufo Class A Amp PCB | Etsy
Regarding the custom choke. I have to do some research. These are heavy items and not easy or inexpensive to ship so I am not sure if I want to burden myself with the headaches that go with it.
I expect to be shipping you the boards in 2-3 weeks.