Hey Owen - I was wondering if you ever built this enclosure? Based you your approach, I drafted a similar case. Dimensions will be 11in deep by 16in (ID) wide and 6in tall. Total width is between 20in and 24in, depending on if heatsink extensions are installed. I found some unique heatsink on eBay for this.
With the height, I partitioned it as two 3in levels. Heatsinks were $35 each, and raw 6061 aluminum came to $166. Wouldn't even tell you what it's costing me to have is milled, drilled, tapped and polished.
I'll just say that I'll not be going 'all in' on a case like this until I build up a small shop with the gear I need to do it myself.
Anyway, as much as I've enjoyed the NTD1, it'll be worth it. Case should be assembled by the end of next week. I'll post pictures
With the height, I partitioned it as two 3in levels. Heatsinks were $35 each, and raw 6061 aluminum came to $166. Wouldn't even tell you what it's costing me to have is milled, drilled, tapped and polished.
I'll just say that I'll not be going 'all in' on a case like this until I build up a small shop with the gear I need to do it myself.Anyway, as much as I've enjoyed the NTD1, it'll be worth it. Case should be assembled by the end of next week. I'll post pictures
Wow! I am green with envy!
That is by far the cleanest implementation of the NTD1 I've seen to date.
Wanna make me one?
Mine is still a tangled mess of wires in my media cabinet
How are the thermals? Does it run at a decent temp?
What is the deal with the output arrangement? I can't quite figure out from looking at it how you hooked it up.
Cheers,
Owen
That is by far the cleanest implementation of the NTD1 I've seen to date.
Wanna make me one?
Mine is still a tangled mess of wires in my media cabinet
How are the thermals? Does it run at a decent temp?
What is the deal with the output arrangement? I can't quite figure out from looking at it how you hooked it up.
Cheers,
Owen
I was planning to use a single transformer for the NTD1 power supply but make a secondary for each supply.
Please let me know if good enough. Also, I am planning for voltage drop for the regulators but want to make sure the safety margin is good enough. I don`t want the regs having to drop too much voltage since I don`t want them to overheat but don`t want them to sag either.
Dual Primary 115/230Vac - 250VA total
Quad Secondaries 41Vac (ea. 55VA) + dual secondary 9Vac (ea. 15VA)
Of course shielded encapsulated.
Anybody have part numbers (Digikey, Mouser, etc) for the BII/BIII headers to the NTD1 PCB?
Thanks
Do
Please let me know if good enough. Also, I am planning for voltage drop for the regulators but want to make sure the safety margin is good enough. I don`t want the regs having to drop too much voltage since I don`t want them to overheat but don`t want them to sag either.
Dual Primary 115/230Vac - 250VA total
Quad Secondaries 41Vac (ea. 55VA) + dual secondary 9Vac (ea. 15VA)
Of course shielded encapsulated.
Anybody have part numbers (Digikey, Mouser, etc) for the BII/BIII headers to the NTD1 PCB?
Thanks
Do
bigpandahk:
The short answer is no... it's an inherently balanced circuit and just taking one phase of the output results is significantly diminished performance.
If you absolutely must have SE output, the I suggest using an op-amp to perform the BAL-SE conversion. A transformer can also be used, but I generally don't recommend it.
If you're looking at a DAC with this sort of performance, IMHO the next stage in the system really should have a differential input, be it a preamp or a power amp.
pinnocchio:
Your secondary AC voltage is a little high if it's a loaded voltage. You'll get about 56VDC on the high side of the regs, and 9V of drop is pretty high.
If I were you, I'd target more like 36-38VAC at nominal (operating) load.
For the connectors, just use standard SIP 0.1" headers and sockets, but remove every other pin.
Cheers,
Owen
The short answer is no... it's an inherently balanced circuit and just taking one phase of the output results is significantly diminished performance.
If you absolutely must have SE output, the I suggest using an op-amp to perform the BAL-SE conversion. A transformer can also be used, but I generally don't recommend it.
If you're looking at a DAC with this sort of performance, IMHO the next stage in the system really should have a differential input, be it a preamp or a power amp.
pinnocchio:
Your secondary AC voltage is a little high if it's a loaded voltage. You'll get about 56VDC on the high side of the regs, and 9V of drop is pretty high.
If I were you, I'd target more like 36-38VAC at nominal (operating) load.
For the connectors, just use standard SIP 0.1" headers and sockets, but remove every other pin.
Cheers,
Owen
nah, those things are well below the capabilities of this IV stage, but then as far as numbers I suspect so are the amps. I have to say i'm somewhat confused at the building a dual mono balanced dac to use with a SE tube amp. I would suggest a nice yet simple discrete opamp normally, but building 2 of them and stuffing in the same case as this... so maybe transformers or a couple of Owens BAL-SE the wire headphone amps if he has any PCBs left. lol in joke
Well, if you wanna go crazy you can try paralleling devices and stuff, but, as already stated, these are going to be the sub-optimal outputs anyway. I wouldn't waste a sexeh and precious Wire there.
yeah... it's a tough call on that side of things.
If it's a 300B amp, then there is at least one transformer, and possibly two in the signal chain already, which would probably push me to suggest simply using another transformer to perform the BAL-SE conversion. If you like the sound of the amp, then you're clearly not bothered by the way transformers sound, so more of the same might be the safer bet.
Using a transformer also lets you reduce the output capacitor count to 1, which can be placed between the two primary windings of the transformer. If you're really adventurous, you could be the first to try it with no coupling caps at all and just slap the transformer across the output of the NTD1 before the output coupling caps.
Lastly, is your amp a 300B SE or 300B PP? If it happens to be push-pull then you could do a little circuit modification and bypass the phase splitter which would essentially make the amp a "differential" amp which could be driven from the NTD1's differential outputs.
If your amp is PP, then the last option is by far the best, and would certainly result in much better performance for both the amp and the DAC.
Cheers,
Owen
If it's a 300B amp, then there is at least one transformer, and possibly two in the signal chain already, which would probably push me to suggest simply using another transformer to perform the BAL-SE conversion. If you like the sound of the amp, then you're clearly not bothered by the way transformers sound, so more of the same might be the safer bet.
Using a transformer also lets you reduce the output capacitor count to 1, which can be placed between the two primary windings of the transformer. If you're really adventurous, you could be the first to try it with no coupling caps at all and just slap the transformer across the output of the NTD1 before the output coupling caps.
Lastly, is your amp a 300B SE or 300B PP? If it happens to be push-pull then you could do a little circuit modification and bypass the phase splitter which would essentially make the amp a "differential" amp which could be driven from the NTD1's differential outputs.
If your amp is PP, then the last option is by far the best, and would certainly result in much better performance for both the amp and the DAC.
Cheers,
Owen
but.... it would result in a much cleaner sound sig, which may not actually be desirable, since it may lose some of that really densely harmonic soundstage that 300B lovers can hold dear. difficult that making recommendations in these circumstances with objectives that can turn out to not be aligned, even though its objectively the 'right' thing to do.
it really depends on the style of tube amp, ive heard some pretty damn clean 300Bs as well. not many admittedly but its not the sort of thing I search out. Its usually the surrounding components that screw with tube amps linearity
Last edited:
After so much speculation let me add mine as well.
Amp won't be a 300B PP. I believe this is a dirty word in HG
As it most probably is a SET i just cannot understand all the obsession with a super duper bal/se convertor. Taking just one phase out appears to be the cleanest solution which will only bring negligible in this context increase in second harmonics and noise.
Amp won't be a 300B PP. I believe this is a dirty word in HG
As it most probably is a SET i just cannot understand all the obsession with a super duper bal/se convertor. Taking just one phase out appears to be the cleanest solution which will only bring negligible in this context increase in second harmonics and noise.
you clearly dont have much of an idea of how the ES9018 works then, you wont 'just' get a small increase in 2nd harmonic.
also its all in series, some of the distortion wont add but not as little as you may think and all of the noise will.
basically all the careful on chip routing and element matching, all the power supply fiddling, all the careful layout, all the mosfet matching, all the zfoil matching and all the expense of dual mono, would be utterly pointless....
it would come to nothing, how exactly are you minimizing that?
also its all in series, some of the distortion wont add but not as little as you may think and all of the noise will.
basically all the careful on chip routing and element matching, all the power supply fiddling, all the careful layout, all the mosfet matching, all the zfoil matching and all the expense of dual mono, would be utterly pointless....
it would come to nothing, how exactly are you minimizing that?
Last edited: