Speaking of bench, I finally spent 5 hours cleaning up the 6 months of accumulated development detritus on the bench, floor, desk, shelves etc. I ran out of horizontal space and the project interleaving became unbearable (not to mention unproductive). Nice to experience and work in an organized and clean lab again. Real mind opening feeling to see a clean space again.
🙂
🙂
On the bench tonight is a desktop version of the Pocket Diamond Buffer headphone amp. I am connecting a nice AC/DC (Recom RAC10-15DK/277) PSU with common mode choke filter +/-15v at +/-340mA followed by a dual rail LT1963 and LT3015 linear low noise voltage regulators to drop it down to +/-9v. I can increase it to +/-12v later after I get the outputs heatsinked. This feeds the PDB board which now has flying leads from the output jack solder pads to an external headphone jack. The audio input comes from two panel mounted RCA jacks connected by RG174 coax to a Molex connector wired to the input jack solder pads. Listening to it now on HE-400i. Very nice. Next step is to install all of this inside a small chassis.
I have some cool news - Jhofland is working on a Desktop Diamond Buffer that uses big Toshiba TTA004 and TTC004 (TO-220) output transisiors. It should make building a desktop amplifier a lot easier.
Like my diamond buffer preamp/headphone amp , which i am listening to right now.
[Don't use more than (±) 15V & Use a capacitor or DC Servo]
It has been tweaked to have dominant 2nd order harmonic with near negative 90 degree phase , Higher odd order are below -120 Degree. I am working on a version with ODNF and even better harmonic profile.
Harmonic Frequency Fourier Normalized Phase Normalized
Number [Hz] Component Component [degree] Phase [deg]
1 1.000e+03 2.855e-01 1.000e+00 -0.00° 0.00°
2 2.000e+03 8.620e-07 3.019e-06 -87.63° -87.62°
3 3.000e+03 1.208e-08 4.231e-08 4.90° 4.91°
4 4.000e+03 9.027e-10 3.162e-09 -173.78° -173.78°
5 5.000e+03 6.326e-10 2.216e-09 -179.91° -179.90°
6 6.000e+03 4.310e-10 1.509e-09 -179.44° -179.43°
7 7.000e+03 2.648e-10 9.276e-10 -179.02° -179.02°
8 8.000e+03 1.259e-10 4.411e-10 -177.98° -177.98°
9 9.000e+03 6.691e-12 2.344e-11 -141.26° -141.26°
Total Harmonic Distortion: 0.000302%(0.000000%)
Can you post image of the schematic - I don’t have LTspice on my phone and can’t get to computer at the moment.
The Oscope revealed a 7MHz oscillation. I added 0.1uF and 47ohm resistor at the outputs and this cured it. This can be added onto the solder pins of the 3.5mm jack. We will update this on a future version and certainly the Desktop DB HPA will have it standard. Fast Class AB amps always need something like this at the output.
Before:
After 100nF and 47R snubber:
The outputs measure 0.0mV AC RMS on Fluke 105. DC offset is 0mV on right and -2mV on left channe. All good now.
Before:
After 100nF and 47R snubber:
The outputs measure 0.0mV AC RMS on Fluke 105. DC offset is 0mV on right and -2mV on left channe. All good now.
On the bench are measurements of the Pocket Diamond Buffer (PDB) HPA. Superb performance - pure Class A up to 125mW, and able to drive 350mW into 33ohms before clipping. Wonderful Class A second harmonic dominant distortion profile with overall low 0.002% THD.
Detailed measurents here:
https://www.diyaudio.com/community/...-buffer-pdb-headphone-amp.401404/post-7519044
Detailed measurents here:
https://www.diyaudio.com/community/...-buffer-pdb-headphone-amp.401404/post-7519044
I am finally getting ready to finish my H2 which is being fed power through a P089ZB. I was waiting for some time for the PSU filter kits to be back in stock, and once they were, I thought it would be fun to try one out with the H2
As it sits, the H2 PCB is mounted with M3 Nylon stand-offs. I plan on initially tying 0 VDC to the chasis soley via the barrel of the DC input jack. The H2 will be powered directly from the output terminals of the P089ZB. This will be my only connection between the H2 board and ground.
Clearance between the PCB and the case is close, hence the Kapton tape.
Signal wires will be solid core twisted pairs scavenged from CAT6 network cable. The input shields are also floating for the time being
Any thoughts on if and how I should deal with the PCB ground? Would grounding the board through conductive stand-offs be better?
Chassis GND fo analog 0v GND should be connected through a ground loop breaker. 10ohms and 100nF in parallel. If PCB has high current on it, then two anti parallel diodes should be used to allow a large short to flow easily.
Hi Folks,
Hope you are all having a good peaceful week leading to the holidays. I myself have been recovering from being sick. Almost back to myself again.
I have a great track for you guys. Listen with good speakers that have bass or with headphones and a good headphone amp.
Whitewash by Buckethead
https://music.amazon.com/albums/B00...0016OA6IU&ref=dm_sh_EjVJ5B1nNIhOSg0kMjpRvpenz
It was JPS64 who introduced me to this artist a few days ago. Kind of obscure but has been around a while.
Hope you are all having a good peaceful week leading to the holidays. I myself have been recovering from being sick. Almost back to myself again.
I have a great track for you guys. Listen with good speakers that have bass or with headphones and a good headphone amp.
Whitewash by Buckethead
https://music.amazon.com/albums/B00...0016OA6IU&ref=dm_sh_EjVJ5B1nNIhOSg0kMjpRvpenz
It was JPS64 who introduced me to this artist a few days ago. Kind of obscure but has been around a while.
Glad you're feeling better! LOL can you give us any previews on upcoming products? how about the subwoofer amp in the down valley 12? I saw it uses a toroid and is class AB
Glad you are feeling better as well, not fun being sick, just getting over a month of hell here, lost 10 lbs, lightest I have weighed in around 40 years....whatever it was it was not a normal bug by any means......hmmmmm.......
I’m glad you asked… 🙂
The final name on that subwoofer is the Vanguard Caldera 10 (“down valley was a working name”). As you may know, a caldera is a deep low valley (or lake) formed by the cataclysmic and powerful eruption of a volcano.
It has a 10in rubber surround long throw woofer sub driver powered by a custom discrete Class AB amplifier powered by a linear toroidal PSU.
Most powered subs nowadays are powered by inexpensive Class D plate amps with switching power supplies. Not the Caldera 10 - we use good old fashioned iron based stomping amps!
Here is the inside of the amp for this sub with discrete output Class AB amp and linear toroidal transformer PSU:
Exterior is a satin textured black synthetic wrap:
Real speaker binding posts for high level inputs and accepts RCA of course:
About similar size (maybe a tad more compact) than Polk PSW10:
Working on the aluminum badge for the subwoofer today (sample after laser etched marking completed):
We also have a 12in Caldera 12 sub in the works coming out later and it’s in a beautiful rosewood veneer similar to the Vanguard Scout. This one is a linear toroidal transformer powered dual rail Class D amp with single ended and balanced signal inputs.
Here is the inside of the amp:
Attachments
Last edited:
awesome! LOL I know many say "fast bass" is a myth. But anything about the sub that makes it especially suited for music instead of home theater?
I am hoping to not need a sub(s) with the XSD speakers but if I do....very interesting indeed🙂
I am still going to test other speakers, mainly my Edgarhorns which absolutely need subs (I would use two subs for most anything I do, just like them better)
Only interested for music as seldom watch movies, TV, etc, and though we have a big RV lot we are closer to some neighbors that we do not want to disturb, just being nice.
I am still going to test other speakers, mainly my Edgarhorns which absolutely need subs (I would use two subs for most anything I do, just like them better)
Only interested for music as seldom watch movies, TV, etc, and though we have a big RV lot we are closer to some neighbors that we do not want to disturb, just being nice.
It’s a bass reflex (ported) subwoofer so has to follow the laws of physics of reflex subs. No it’s not “fast”. But for a sub to be good for music means that it should integrate well with a speaker as high as 120Hz and be able to help out in that region smoothly. Having a discrete Class AB amp and has a linear power supply probably counts for something if you are more interested in music vs HT. This linear PSU and linear amp alone makes it very different compared to most other subwoofers in this (budget) price range.
The XSD speaker is what I would say has very articulate and snappy bass.