You are the only one I know with an inverter setup. There is a definite advantage to choke-loaded amps for you because the choke doesn’t drop voltage like a resistor or a CCS; it stores it in the magnetic field, which is kinda like magic. So, you don need the extra voltage and heat dissipation and power draw. Works in your favor 
Number three has had a few surprises.
Vgs is 3.0 V where the first two were 3.6 V. I did buy the devices in two transactions.
I am using about half of the resistance to get close to 2.5A
STILL did not get the amps installed so I cannot claim they make sound, yet. Will know this afternoon.
Re-making an amplifier gives one many chances to do things better and that has taken time.
Should have plenty of time this long weekend to convert number four.
Listening in mono to the side with TDV reveals a much wider soundfield than the same side with SB. Now I am not sure if that is a sign of less or more phase anomalies. My guess would be less but I am using a CINEMAG transformer at the input to convert the balanced output of the DAC to the TDV so who knows. Looking forward to hearing how this affects stereo.
Vgs is 3.0 V where the first two were 3.6 V. I did buy the devices in two transactions.
I am using about half of the resistance to get close to 2.5A
STILL did not get the amps installed so I cannot claim they make sound, yet. Will know this afternoon.
Re-making an amplifier gives one many chances to do things better and that has taken time.
Should have plenty of time this long weekend to convert number four.
Listening in mono to the side with TDV reveals a much wider soundfield than the same side with SB. Now I am not sure if that is a sign of less or more phase anomalies. My guess would be less but I am using a CINEMAG transformer at the input to convert the balanced output of the DAC to the TDV so who knows. Looking forward to hearing how this affects stereo.
Three working with one left to convert.
Now with TDV on both tweeters (400 Hz and above) and TDV on the left woofer and SB on the Right woofer, in my system, the follower is superior.
I get the feeling the follower amp takes control of the woofers much more firmly than SB can.
The atmospherics of the follower with the tweeters is quite a surprise. The top two octaves are much better defined and it sounds to my frequency range limited ears that there is more output up there also. You can detect overtones that were glossed over before. No changes were made to the EQ.
For hose using DSP with lots of inherent gain there is no question the follower is the way to go.
One wonders if what I am hearing is all amplifier or the fact that I am not using anywhere near as much attenuation in the digital "domain" as before? Well, I will never know for sure but it seems like it should be better. Luckily, whatever the cause it is better. Not as if the SBs were not revelatory in their own right.
Well worth the trouble. Thanks, yet, again to ra7 for the thread and the B minus schematic, thanks to cody for making me decide to do this and to Ben Mah for his wise counsel.
Now with TDV on both tweeters (400 Hz and above) and TDV on the left woofer and SB on the Right woofer, in my system, the follower is superior.
I get the feeling the follower amp takes control of the woofers much more firmly than SB can.
The atmospherics of the follower with the tweeters is quite a surprise. The top two octaves are much better defined and it sounds to my frequency range limited ears that there is more output up there also. You can detect overtones that were glossed over before. No changes were made to the EQ.
For hose using DSP with lots of inherent gain there is no question the follower is the way to go.
One wonders if what I am hearing is all amplifier or the fact that I am not using anywhere near as much attenuation in the digital "domain" as before? Well, I will never know for sure but it seems like it should be better. Luckily, whatever the cause it is better. Not as if the SBs were not revelatory in their own right.
Well worth the trouble. Thanks, yet, again to ra7 for the thread and the B minus schematic, thanks to cody for making me decide to do this and to Ben Mah for his wise counsel.
I am sure it is getting boring by now - the fourth TDV came together with ease on Saturday.
I had used the 1500 uF PP as my only output capacitor on the tweeter amps but now I'm using the same setup on all four - the KEMET slit foil and the big PPs. I had tried them with just the PPs and there is something added, certainly not bass, to the sound that is good. I should not have doubted that 10 mF were needed there with whatever augmentation one has on hand. The unfounded fear of electreolytic capacitors.
One has to think that an amplification device that maintains its stability in such a simple manner is meant to be. No potential sources of distortion and unmusical sounds are added. Even though I will eventually try fixed bias just to hear it.
I had used the 1500 uF PP as my only output capacitor on the tweeter amps but now I'm using the same setup on all four - the KEMET slit foil and the big PPs. I had tried them with just the PPs and there is something added, certainly not bass, to the sound that is good. I should not have doubted that 10 mF were needed there with whatever augmentation one has on hand. The unfounded fear of electreolytic capacitors.
One has to think that an amplification device that maintains its stability in such a simple manner is meant to be. No potential sources of distortion and unmusical sounds are added. Even though I will eventually try fixed bias just to hear it.
I gotthe 1500 uF PPs from an EBAY seller. They had been used in some kind of solar setup - I know nothing about that stuff.
Made by DUCATI and in a case the size of a large motorcycle battery.
The KEMETs are available from MOUSER. HIFI COLLECTIVE used to carry them though I have not looked recently.
https://www.mouser.com/ProductDetail/80-ALC10S1104DL
I started on this project mainly because of what Cody said about followers AND to be able to lessen the load on the inverter/battery. I am very pleased about how much better they sound. I do not hear any shortcomings and figure no one wants to read the tiresome litany of the usual list of improvements. I think one can safely say the TDV does everything, at least, a little better.
Thanks for this, ra7.
Just looked and I know this is who I got mine from many years ago. I thought mine were used and these are said to be new. Not sure if the ones I got have a higher voltage rating. Same case.
https://www.ebay.com/itm/332020165715
Made by DUCATI and in a case the size of a large motorcycle battery.
The KEMETs are available from MOUSER. HIFI COLLECTIVE used to carry them though I have not looked recently.
https://www.mouser.com/ProductDetail/80-ALC10S1104DL
I started on this project mainly because of what Cody said about followers AND to be able to lessen the load on the inverter/battery. I am very pleased about how much better they sound. I do not hear any shortcomings and figure no one wants to read the tiresome litany of the usual list of improvements. I think one can safely say the TDV does everything, at least, a little better.
Thanks for this, ra7.
Just looked and I know this is who I got mine from many years ago. I thought mine were used and these are said to be new. Not sure if the ones I got have a higher voltage rating. Same case.
https://www.ebay.com/itm/332020165715
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We do want to hear what you are hearing 
. I don’t know of anyone else on the forum with a setup like yours.Correct me if I am wrong, but you have the Axi2050 on a horn crossed actively to a woofer. And it is being driven by four separate VFET amps powered by an inverter and battery. That is unique!
. I don’t know of anyone else on the forum with a setup like yours.Correct me if I am wrong, but you have the Axi2050 on a horn crossed actively to a woofer. And it is being driven by four separate VFET amps powered by an inverter and battery. That is unique!The AXI2050 and two Crites/Eminence woofers in a KLIPSCH K402 horn for each channel driven by the exemplary TDV amplifiers. There are four RYTHMIK 15 inches woofers for the low bass.
I feel certain this is my last system.
I think it is very good but I am always finding new things to do to it.
The inverter was inspired by Michael Fremer's article on his AC power modification. I knew I could not afford that but my cusriosity was rasied as to how AC power affects our gear.
With SB I could get about fours hours of listening time which is longer than I ever listen to music. My system does not do well at background music. With TDV I figure I could get almost six hours so this will make life easy on the batteries - two 200Ah LiFePo. The digital stuff is run from a 200 Ah gel SLA.
The big inverter has a 21kHz noise spike - I cannot hear it but the REW RTA shows it. The small one has a 22 kHz spike of lower amplitude. I have treid all kinds of coverings of the inverters to make the inverters quiet and nothing so far has worked. I am beginning to think the noise is generated by the power lines. It would be really expensive to shield all of the AC wire so I have not tried that. There is no question it is the inverters since the only way to get it to go away is to turn off the inverter. So even though I do not think it is affecting my listening enjoyment I do know that it should not be there.
In all other respects the inverters are a success. Of course, I have no way to switch back and forth from GEORGIA POWER to inverter power but I am confident it has made a worthwhile difference.
The inverters keep a much steadier voltage than the line as measured with my FLUKE meter. Not a top of the line one.
All I can say is the coherency which is the promise of the Danley UNITY concept is made all the more coherent with the TDV amplifier. I keep coming back to the rich tonality of the amplifiers - the transparent window I am listening through - what Herb Rechert would call corporeality - one can imagine there are musicians a few feet in front of you.
The SINGING BUSH were hardly slouches but this circuit, for my system, is superior.
It might be an unfair comparison since the no gain TDV works better in my system by not requiring the dramatic attenuation in the DSP box as the SB. Makes me think for those who use a DSP box as the heart of their system follower amplifiers are what is needed.
Another big change is using the CINEMAG transformers at the input of the TDCs to take advantage oif the balanced outputs of the DACs. Last thing I needed with the SBs was more gain!
I still wonder if a buffer would improve things between DACs and amplifiers?
I feel certain this is my last system.
I think it is very good but I am always finding new things to do to it.
The inverter was inspired by Michael Fremer's article on his AC power modification. I knew I could not afford that but my cusriosity was rasied as to how AC power affects our gear.
With SB I could get about fours hours of listening time which is longer than I ever listen to music. My system does not do well at background music. With TDV I figure I could get almost six hours so this will make life easy on the batteries - two 200Ah LiFePo. The digital stuff is run from a 200 Ah gel SLA.
The big inverter has a 21kHz noise spike - I cannot hear it but the REW RTA shows it. The small one has a 22 kHz spike of lower amplitude. I have treid all kinds of coverings of the inverters to make the inverters quiet and nothing so far has worked. I am beginning to think the noise is generated by the power lines. It would be really expensive to shield all of the AC wire so I have not tried that. There is no question it is the inverters since the only way to get it to go away is to turn off the inverter. So even though I do not think it is affecting my listening enjoyment I do know that it should not be there.
In all other respects the inverters are a success. Of course, I have no way to switch back and forth from GEORGIA POWER to inverter power but I am confident it has made a worthwhile difference.
The inverters keep a much steadier voltage than the line as measured with my FLUKE meter. Not a top of the line one.
All I can say is the coherency which is the promise of the Danley UNITY concept is made all the more coherent with the TDV amplifier. I keep coming back to the rich tonality of the amplifiers - the transparent window I am listening through - what Herb Rechert would call corporeality - one can imagine there are musicians a few feet in front of you.
The SINGING BUSH were hardly slouches but this circuit, for my system, is superior.
It might be an unfair comparison since the no gain TDV works better in my system by not requiring the dramatic attenuation in the DSP box as the SB. Makes me think for those who use a DSP box as the heart of their system follower amplifiers are what is needed.
Another big change is using the CINEMAG transformers at the input of the TDCs to take advantage oif the balanced outputs of the DACs. Last thing I needed with the SBs was more gain!
I still wonder if a buffer would improve things between DACs and amplifiers?
Hi
I’m about to order everything from Digikey but then was thinking about the power supply. I’d like to build 2 mono bloc and each of them would be powered via a 19Vdc laptop supply. I did this for my regular MoFo and had great results.
Can someone confirm if this amp would work properly at 19V (bias at 1.6A?) instead of about 24-28Vdc. Also, would the expected output power be similar to the MoFo (10W is plenty for me, picture attached) and last, would I need to change any components values if I use my 19Vdc supply.
Thanks a lot for your time.
Eric
I’m about to order everything from Digikey but then was thinking about the power supply. I’d like to build 2 mono bloc and each of them would be powered via a 19Vdc laptop supply. I did this for my regular MoFo and had great results.
Can someone confirm if this amp would work properly at 19V (bias at 1.6A?) instead of about 24-28Vdc. Also, would the expected output power be similar to the MoFo (10W is plenty for me, picture attached) and last, would I need to change any components values if I use my 19Vdc supply.
Thanks a lot for your time.
Eric
Attachments
It doesn’t happen with my TDV but I haven’t really tested it. Not really an indication of a problem though I am not sure of how the gate in the Tokin behaves under zero Vds. The Tokins gate draw is not insignificant under certain operating conditions. Rick, you can try measuring if there is any voltage on the drain with the amp switched off.
