On the bench tonight is some solder slinging after a long time not building anything amp related.
New All Cee’s PSU adapted for Class A operation as CRC. 15,000uF high ripple current rates caps and Dale 13W 0.33R resistors standing on end. Chassis mounted silicon GBJ bridge. This is going to go in the A25… I mean A40 chassis which will run with Alpha Nirvana in dual mono. 60,000uF per channel.
New All Cee’s PSU adapted for Class A operation as CRC. 15,000uF high ripple current rates caps and Dale 13W 0.33R resistors standing on end. Chassis mounted silicon GBJ bridge. This is going to go in the A25… I mean A40 chassis which will run with Alpha Nirvana in dual mono. 60,000uF per channel.
On the bench tonight is the All Cee’s PSU first test with 23vac trafo. Under no load with 120vac mains I am getting 35vdc. I am hoping for about 29vdc under 1.5A Class A load.
Quick and dirty test using 100W 8ohm dummy load yielded 24v at 5.8A load. Way higher than 1.5A I am planning. I think I am going to be closer to 31vdc under load and not 29v.
Quick and dirty test using 100W 8ohm dummy load yielded 24v at 5.8A load. Way higher than 1.5A I am planning. I think I am going to be closer to 31vdc under load and not 29v.
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I just want to point out that the All Cee’s PSU uses a single bridge rectifier for dual rails, hence it is designed for either a center tapped trafo or you have to connect the secondaries in series and the common tap to GND (the middle pins) on the PCB. My trafo did not have labeled polarity secondaries (both same color) but the position in the wrapping was an indication. However, to make sure, I observed the waveform with an o-scope to make sure I got the “dots” on the trafo secondaries correct. If you don’t do this, you have a 50/50 chance it’s backwards and it will result in a short and you will pop your fuse instantly and hear the trafo hum loudly when turning on.
Everything went smoothly since I checked first and labeled the wire with red shrink tube.
Everything went smoothly since I checked first and labeled the wire with red shrink tube.
On the bench tonight is the Warp-1 amp. I measured the output impedance using 38Vpp excitation on 10ohm 300w non inductive dummy load compared to 1.2kohm 1W metal thin film resistor. Owon oscilloscope and Fluke 116 DMM. Data taken at 1kHz, 100Hz, 50Hz, 30Hz, 20Hz, 10Hz.
Output impedance dropped the bot get with 1.2k ohm from 38.40Vpp to 38.20Vpp with 10 ohms in a flat response from 1kHz to 20Hz. For output impedance of (38.40-38.20)/38.20=0.0052 ohm. That’s same as 191 DF. When I took it to 10Hz, it went up 21 milliOhms (DF=48).
This backs up all the observations by reviewers that the bass is incredibly powerful. They say it has exaggerated bass but I think compared to many amps that have higher output impedance at the registers it may sound exaggerated but it’s only acting neutral.
Output impedance dropped the bot get with 1.2k ohm from 38.40Vpp to 38.20Vpp with 10 ohms in a flat response from 1kHz to 20Hz. For output impedance of (38.40-38.20)/38.20=0.0052 ohm. That’s same as 191 DF. When I took it to 10Hz, it went up 21 milliOhms (DF=48).
This backs up all the observations by reviewers that the bass is incredibly powerful. They say it has exaggerated bass but I think compared to many amps that have higher output impedance at the registers it may sound exaggerated but it’s only acting neutral.
Investigations on really old digital Reverb structures. These are the responses:
First one is from the 60's, and the second one is end of 70's. At that time, it took that long to improve just the understanding of the macro-structure to include a separate treatment for early reflections and the late ones. Nevertheless, even the 70's one is quite simplistic. It does sound like a Reverb, but it's not claiming to be a great Reverb.
This is from taking a break from working on Sound Sources. More info here.
First one is from the 60's, and the second one is end of 70's. At that time, it took that long to improve just the understanding of the macro-structure to include a separate treatment for early reflections and the late ones. Nevertheless, even the 70's one is quite simplistic. It does sound like a Reverb, but it's not claiming to be a great Reverb.
This is from taking a break from working on Sound Sources. More info here.
I got the same SSR / Heatsink combo, with the panel mount temperature controller I bought off ebay, to fix my baking oven. (just behind the second big green resistor)
On the bench tonight is assembling the Alpha Nirvana internals into the XSA Labs Series One A40 amp. Drilled and tapped 15 holes. Installed PSU and trafo and managed to make it orthogonal. Moving along today.
The A40 is up and running!
Always on Meanwell AC/DC module to
provide low voltage ON/OFf signal for SSR.
I am using the low capacitance PSU that comes with speaker protect SSR to give instant off. No turn on or turn off thump.
AN boards and snubber helper boards:
The 23v 200VA trafo gives +/-30.4V rails under Class A the load and 1.78A bias current. All Cee’s PSU caps running cool, 0.33R 13W resistor is cool at 51C. Trafos are cool at 32C. The only thing hot is the heatsink at 55C and 56C. The sound is great - usual Alpha Nirvana but I have to imagine the larger rails will give close to 45W. The bass is amazing - typical Alpha Nirvana bass. DC offset is -3mV and -6mV. Noise with input shorted is 0.2mV rms on right and 0.5mV rms on left.
Always on Meanwell AC/DC module to
provide low voltage ON/OFf signal for SSR.
I am using the low capacitance PSU that comes with speaker protect SSR to give instant off. No turn on or turn off thump.
AN boards and snubber helper boards:
The 23v 200VA trafo gives +/-30.4V rails under Class A the load and 1.78A bias current. All Cee’s PSU caps running cool, 0.33R 13W resistor is cool at 51C. Trafos are cool at 32C. The only thing hot is the heatsink at 55C and 56C. The sound is great - usual Alpha Nirvana but I have to imagine the larger rails will give close to 45W. The bass is amazing - typical Alpha Nirvana bass. DC offset is -3mV and -6mV. Noise with input shorted is 0.2mV rms on right and 0.5mV rms on left.
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is VeraFi going to be your own brand of amps? the case looks gorgeous
edit: what's the difference between the alpha nirvana and the amp you were originally going to put in here? both 40 watt class A aren't they?
edit: what's the difference between the alpha nirvana and the amp you were originally going to put in here? both 40 watt class A aren't they?
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That amp looks fantastic, I love the VU Meters.
Oddly enough I power my dual mono TPA3255 amp in a very similar way, a 12v always on Mean Well that controls a Songle mechanical relay, and a bypass switch hooked up to a 12v relay for trigger input selection.
Just Friday I tried to swap the mechanical relay out to a Crydom 84134210 (https://www.mouser.com/ProductDetail/874-84134210) and while functionally it worked, trigger controlled power on/off was silent, but it introduced some sort of odd and faint click/scratch noise from the speakers into the mix, and once I swapped back to the Songle mechanical relay the noise went away, unfortunate as I was excited to finally install the SSR I had sitting on my shelf for months.
Double oddly, I have some Fotek SSR-40 DA's as well that I didn't try. I'm curious if the Fotek SSR-40 DA's would have the same effect or if they would be good to use in that application? I'm keen to get the amp quietly turning off/on as well as the extended lifespan of an SSR. I figured I would ask before I go through the hoops of testing it out 😀
Oddly enough I power my dual mono TPA3255 amp in a very similar way, a 12v always on Mean Well that controls a Songle mechanical relay, and a bypass switch hooked up to a 12v relay for trigger input selection.
Just Friday I tried to swap the mechanical relay out to a Crydom 84134210 (https://www.mouser.com/ProductDetail/874-84134210) and while functionally it worked, trigger controlled power on/off was silent, but it introduced some sort of odd and faint click/scratch noise from the speakers into the mix, and once I swapped back to the Songle mechanical relay the noise went away, unfortunate as I was excited to finally install the SSR I had sitting on my shelf for months.
Double oddly, I have some Fotek SSR-40 DA's as well that I didn't try. I'm curious if the Fotek SSR-40 DA's would have the same effect or if they would be good to use in that application? I'm keen to get the amp quietly turning off/on as well as the extended lifespan of an SSR. I figured I would ask before I go through the hoops of testing it out 😀
It’s hard to say what will happen with these things as there are electronic interactions between the triac in the SSR and the PSU perhaps. I think the Fotek makes the trafo have a little more mechanical hum, but that doesn’t show up in the sound at the speakers. Just try it.
Vera-Fi Audio and XSA Labs are new brands I am establishing with my business partner.
Vera-Fi Audio and XSA Labs are new brands I am establishing with my business partner.
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I moved the A40 over to the main rack and connected them to the XSDs. Wow, the soundstage and imaging of dual mono Class A is very wide and deep.
I had some hum on right channel and rotated the trafo on the left by 90 deg and it went away. It moved the wires away from the amp. Sometimes little things make all the difference.
I had some hum on right channel and rotated the trafo on the left by 90 deg and it went away. It moved the wires away from the amp. Sometimes little things make all the difference.
That sound is great, you really have me wanting to build a dual mono Alpha Nirvana myself, I'll add it to the list but I have a few other amp projects like the FH9HVX first. Can I ask what those placemat-sized PCB's underneath the amp are?
Btw, I gave the Fotek SSR a shot, no problems and not a hint of scratch/click or whatever the noise was, I checked block diagrams of the Fotek and Crydom, Fotek has a zero crossing circuit whereas Crydom doesn't. Live and learn, hopefully a project that can make use of the Crydom is in my future 😀
Btw, I gave the Fotek SSR a shot, no problems and not a hint of scratch/click or whatever the noise was, I checked block diagrams of the Fotek and Crydom, Fotek has a zero crossing circuit whereas Crydom doesn't. Live and learn, hopefully a project that can make use of the Crydom is in my future 😀
Glad you like the sound of the amp and happy to hear that the Fotek
Zero crossing circuit did the trick.
You have sharp eyes. Those placemat sized PCBs are precision X-ray targets for calibrating the distortion of large fluoroscopy machines. I also do work in medical devices field. They work well as placemats for amps. 🙂
Zero crossing circuit did the trick.
You have sharp eyes. Those placemat sized PCBs are precision X-ray targets for calibrating the distortion of large fluoroscopy machines. I also do work in medical devices field. They work well as placemats for amps. 🙂
Another recording I made at same time but forgot to post. Drum solo to show some resolving cymbals and brushwork.
New preamp test module for an integrated desktop amp I am building for Vera-Fi Audio. This is based on the PCA topology but uses LSK389 dual JFET. Also has voltage regulators for the rails. Jhofland did the superb layout and he built the verification units. The left right channel balance set points are nearly perfect as you would imagine with a dual JFET.
On the bench tonight is some serious solder slinging. The Bob Carver RPM V12 preamp main board and PSU boards need to be stuffed. An all tube preamp with mostly big SMT parts. Through hole will be used for large electrolytic and film caps though. This will be fun.
What's the plan for the smd's, using the skillet, solder paste, and hot air or some other method? 🤔
