Rahul,
I am using the B- version of the TDV where you recommended 6.2K Ohms for the input load resistor - I am either using one of that value or 6.7K - I am wondering if one can go lower than that?
Over the weekend I thought I would see what happens when I replace what was a 2.5 uF DUELUND capacitor with one sized for a 2000 Hz high pass, .01uF. I have these great silver micas I got from Mr. Yazaki at SPEC CORP so that is what I inserted.
I figured instead of using the DSP box to do all of the frequency levelling the cap would take some of the attenuation load from the DSP. It does - I am able to eliminate half of the PEQs I was using and the resulting response is smoother.
So there are two questions - can you see any pitfall with an input cap of such a small value? I was thinking about lowering the value of the load resistor so I could use a larger capacitor.
It all sounds very good but on the odd occasion I hear a crack from one channel - only once last night. The levels are such that it is not a voice coil slapping the bottom of its gap and I cannot imagine it being a digital overload sound. I worry that it might be suspect soldering - which I will re-solder this evening.
Can you think of any reason this could cause distress with the TDV circuit and what effect would halving the load resistor have?
Do I need to consider power rating of this resistor? I am using a Texas Components Z foil - 0,7 watt.
At your leisure if you think this is worth the time.
Thanks,
I am using the B- version of the TDV where you recommended 6.2K Ohms for the input load resistor - I am either using one of that value or 6.7K - I am wondering if one can go lower than that?
Over the weekend I thought I would see what happens when I replace what was a 2.5 uF DUELUND capacitor with one sized for a 2000 Hz high pass, .01uF. I have these great silver micas I got from Mr. Yazaki at SPEC CORP so that is what I inserted.
I figured instead of using the DSP box to do all of the frequency levelling the cap would take some of the attenuation load from the DSP. It does - I am able to eliminate half of the PEQs I was using and the resulting response is smoother.
So there are two questions - can you see any pitfall with an input cap of such a small value? I was thinking about lowering the value of the load resistor so I could use a larger capacitor.
It all sounds very good but on the odd occasion I hear a crack from one channel - only once last night. The levels are such that it is not a voice coil slapping the bottom of its gap and I cannot imagine it being a digital overload sound. I worry that it might be suspect soldering - which I will re-solder this evening.
Can you think of any reason this could cause distress with the TDV circuit and what effect would halving the load resistor have?
Do I need to consider power rating of this resistor? I am using a Texas Components Z foil - 0,7 watt.
At your leisure if you think this is worth the time.
Thanks,
You can go lower but the preceding stage should be able to drive it. I would say 4.7k is the general limit. Power rating is not so important.
With a smaller resistor, you need a larger coupling cap… this is before finishing morning tea
With a smaller resistor, you need a larger coupling cap… this is before finishing morning tea
Hi Rahul
Would you happen to have a graph of the THD vs. Output Power in watts ?
I made some progress on my monoblocs and my friend would like to also build it, he’s got lower efficiency speakers therefore was asking about the output power into 8 ohm. His supply would be 24Vdc biased at about 1.4A per your schematic on post no.26
I’m expecting about 15W but it would be nice if you could confirm.
Thanks
Eric
Would you happen to have a graph of the THD vs. Output Power in watts ?
I made some progress on my monoblocs and my friend would like to also build it, he’s got lower efficiency speakers therefore was asking about the output power into 8 ohm. His supply would be 24Vdc biased at about 1.4A per your schematic on post no.26
I’m expecting about 15W but it would be nice if you could confirm.
Thanks
Eric
It has dropped to 20V but used to be 25V. Had to use the transformer for horsing around elsewhere. 20-25V is fine. 30V and 2 amps might be getting too much for the device even though it is quite large. On the THF51 and 2sk180, 60W might be fine.
Hi,
Just for fun, below are pics of my TDV monoblocs. Physically they are done, I kept the rugged industrial look, what’s left is the wiring. I’ve never heard a VFET/SIT so I can’t wait.
This design comes from the idea that I had some 0.44c/w heatsinks I wanted to use (6.5” x 6.5” x 7” high) so I managed to have the heatsink being the amp...nothing else needed except the power supply.
Each monobloc will be powered by a 24Vdc, 5A smps + Mark’ Filter.
Thanks to all who made this possible 👍
Older pic showing the top view
Eric
Just for fun, below are pics of my TDV monoblocs. Physically they are done, I kept the rugged industrial look, what’s left is the wiring. I’ve never heard a VFET/SIT so I can’t wait.
This design comes from the idea that I had some 0.44c/w heatsinks I wanted to use (6.5” x 6.5” x 7” high) so I managed to have the heatsink being the amp...nothing else needed except the power supply.
Each monobloc will be powered by a 24Vdc, 5A smps + Mark’ Filter.
Thanks to all who made this possible 👍
Older pic showing the top view
Eric
Last edited:
It’s a member of Canuck Audio Mart who has a bunch for sale, each heatsink is $4 usd...
Hi guys
Tonight I have finally heard a VFET and I’m thrilled, the sound is not like what I’m used to, it’s very addictive. Thanks a lot RA7, excellent sounding amp.
p.s. I have a big thump when I turn off the DC side (24V) of the power supply via my switch in the front, am I the only one with that issue?
My closing sequence is: Power amp then pre-amp.
I think my sensitive full range probably skipped a heart beat, just like I did...lol
Thanks
Eric
Tonight I have finally heard a VFET and I’m thrilled, the sound is not like what I’m used to, it’s very addictive. Thanks a lot RA7, excellent sounding amp.
p.s. I have a big thump when I turn off the DC side (24V) of the power supply via my switch in the front, am I the only one with that issue?
My closing sequence is: Power amp then pre-amp.
I think my sensitive full range probably skipped a heart beat, just like I did...lol
Thanks
Eric
Eric,
Plug your smps bricks into a power strip with a switch. Leave your mono amp power switches on and use the power strip switch to turn them on and off. See if this reduces the thump.
Plug your smps bricks into a power strip with a switch. Leave your mono amp power switches on and use the power strip switch to turn them on and off. See if this reduces the thump.