WOBT - June 12, 2021: Well not exactly a bench, but this is what’s on my desk. CAD production drawings for a new product that needs review - a hybrid tube/SS headphone amp I have developed with Jhofland in collaboration with Living Sounds Audio. It’s going to be quite a head turner I think. The HyperDrive-2 will have 3 selectable inputs, a preamp output, a tube buffer stage, fully protected outputs and anti thump logic control via a microcontroller for graceful power up and shutdown. It will drive 2w into 32ohms and make clean, engaging and transparent sound, and will come encased in a beautiful custom thick, aluminum powder coated chassis. This is a preliminary render - a few cosmetic details still need to be worked out (upside down volume dial):
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And here is the functional proof of concept prototype in a Hammond case:
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Agree, nice work Anand 😉
I had a bit of time myself to sling a little solder Sunday afternoon on my bench. This is the LuFo amplifier verification build. Once I receive the IMS adapter’s loaded with LU1014D’s I can proceed.
I had a bit of time myself to sling a little solder Sunday afternoon on my bench. This is the LuFo amplifier verification build. Once I receive the IMS adapter’s loaded with LU1014D’s I can proceed.
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Vunce,
Great soldering and great photo! Did you take it outside where there is plenty of light?
Best,
Anand.
Great soldering and great photo! Did you take it outside where there is plenty of light?
Best,
Anand.
Excellent sleuthing fellas!! You are both correct, full board is an outside pic, close-up was on the bench 😉
I should have noticed the tiny little corners on top showing a weathered wood picnic bench in your back yard. That does look like bright cloudy weather lighting though. We were both right!
What doughter board will you try?
A PC USB scope I have designed.
Just low speed (10 mega samples/second) so ok for audio.
Has analogue and spectrum analyser displays.
Partly built, waiting for more components.
A2D is fun to solder on 0.55mm pitch !
PIC processor is 1mm pitch so a bit easier.
Just low speed (10 mega samples/second) so ok for audio.
Has analogue and spectrum analyser displays.
Partly built, waiting for more components.
A2D is fun to solder on 0.55mm pitch !
PIC processor is 1mm pitch so a bit easier.
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Thanks Pepp!
I’m going to use my AKSA Lender Preamp for the initial testing, it was designed specifically to drive 0dB gain amps. Afterwards, I can choose from any of the M2X daughter boards in my stable. (All except the Korg Nutube DB’s) 😉
I’m going to use my AKSA Lender Preamp for the initial testing, it was designed specifically to drive 0dB gain amps. Afterwards, I can choose from any of the M2X daughter boards in my stable. (All except the Korg Nutube DB’s) 😉
That’s a neat project Nigel, a scope is an essential tool in DIY and amazing to see that you can make one from scratch using an ADC and a Pic MCU!
Thanks, Peppenino for the link to the dual monoblock chassis. It’s a beast! I was thinking since it has two dual 5Ux350mm deep heatsinks each, one could make a balanced LuFo amp - the SuSyLu, which can make up to 100w of SE Class A power with only 28v single rail. Predicted distortion at 1W has gone done from 0.01% to 0.0007% in this configuration.
Thanks, Peppenino for the link to the dual monoblock chassis. It’s a beast! I was thinking since it has two dual 5Ux350mm deep heatsinks each, one could make a balanced LuFo amp - the SuSyLu, which can make up to 100w of SE Class A power with only 28v single rail. Predicted distortion at 1W has gone done from 0.01% to 0.0007% in this configuration.
Studying this schematic some more on the desk / computer sim tonight. The transformer is center tapped so if the DC bias current flows from two legs to the center tap, the field cancels and you don't have to worry about saturation. Having the ability to generate 80Vpp from a single 28vdc rail still intrigues me - it just seems fantastical, but that is the property of stored magnetic energy in a transformer.
The Blue trace is the postive phase leg, the Red trace is the negative phase leg, and the Green is the difference applied at the balanced drive output to the speaker. We can see that there is 80Vpp into 8ohms (100w rms) from a 28Vdc single rail PSU.
The Blue trace is the postive phase leg, the Red trace is the negative phase leg, and the Green is the difference applied at the balanced drive output to the speaker. We can see that there is 80Vpp into 8ohms (100w rms) from a 28Vdc single rail PSU.
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Without considering the non-linearity of the output x-former your THD-simulations maybe far away from reality.
Post 1 of the LuFo thread (1/2 of the SuSyLu amp) had simulations that predicted the THD at 1W and 8w to be 0.01% and 0.03% and also the harmonic profile. When I measured the THD at 1W and 8W I actually got the same: 0.01% and 0.03%. If it breaks down, it will be somewhere at higher powers I suppose.
LuFo Amp - 39w SE Class A from 28v Rail
LuFo Amp - 39w SE Class A from 28v Rail
Time flies – halfway to next Xmas and only now Dibya's TDA7293 Xmas amp is on my bench. But great to be slinging some solder again. I was looking forward to winding my own inductors, but in the end it was frustrating. But not as frustrating as the mixed up BOM from my local supplier who managed to send some wrong components – substitutes for out-of-stock stuff. Had to re-order some caps. So, this amp will be on the bench for some time until I have all the components.
After all this trouble I sincerely hope this amp (with a gazillion more parts) will sound better and de-throne my trusted $2 TDA7297 amp who has been giving great service for the last 4 years.
After all this trouble I sincerely hope this amp (with a gazillion more parts) will sound better and de-throne my trusted $2 TDA7297 amp who has been giving great service for the last 4 years.
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Hi Twocents,
Nice work on your Xmas amp build! The inductor looks great! If you are asking if this Xmas amp will beat the Lunch money amp, I have no doubt you will be very happy with the result. It’s a superb amplifier. One of the best chip amps I have heard. The sound is very neutral yet engaging, with nice bass impact. I have been using it for past 5 days and really enjoying it. I am driving it with a new solid state buffer hybrid preamp with a tube interstage buffer. Basically a BTSB with an ECC88 SET buffer. Complete with SSR muting and anti-pop features.
Nice work on your Xmas amp build! The inductor looks great! If you are asking if this Xmas amp will beat the Lunch money amp, I have no doubt you will be very happy with the result. It’s a superb amplifier. One of the best chip amps I have heard. The sound is very neutral yet engaging, with nice bass impact. I have been using it for past 5 days and really enjoying it. I am driving it with a new solid state buffer hybrid preamp with a tube interstage buffer. Basically a BTSB with an ECC88 SET buffer. Complete with SSR muting and anti-pop features.
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