The NTD1 V3 and NTD1 PSU arrived today, great job Owen!
Also, I found that you can order Bourns 390R/1%/35W (PWR263S-35-3900FE) from Mouser even for 1 piece, except there is a 5 weeks lead-time. Price is very reasonable except it's a 100ppm part.
Still, if there is a GB for the Reidon parts taking place, I would like to join.
Thanks!
Also, I found that you can order Bourns 390R/1%/35W (PWR263S-35-3900FE) from Mouser even for 1 piece, except there is a 5 weeks lead-time. Price is very reasonable except it's a 100ppm part.
Still, if there is a GB for the Reidon parts taking place, I would like to join.
Thanks!
If your trimmer makes a small proportion of the total resistance then it's tempco contribution automatically becomes a small proportion.
this applies to both a series connected trimmer and to a parallel connected trimmer.
eg 10k 25ppm fixed resistor plus 1k 300ppm VR gives a total tempco of ~50ppm
or, 11k 25ppm fixed resistor in parallel with a 100k 300ppm VR gives a total tempco of ~50ppm.
Keep the VR a small proportion of the total resistance and it's tempco is not a concern.
this applies to both a series connected trimmer and to a parallel connected trimmer.
eg 10k 25ppm fixed resistor plus 1k 300ppm VR gives a total tempco of ~50ppm
or, 11k 25ppm fixed resistor in parallel with a 100k 300ppm VR gives a total tempco of ~50ppm.
Keep the VR a small proportion of the total resistance and it's tempco is not a concern.
hi all,
owen seems quite busy, so i will post here my question to him:
<begins pm to owen>
hi Owen!
first of all, thanks for your efforts!
one question though, on my paypal (german/austrian version of the website) it asks if i want to send money to a friend or pay for some service or article.
which one should i choose? (i think the difference lies in the paypal fees)
cheers!
daniel
<ends pm to owen>
would any of you know which option to choose?
owen seems quite busy, so i will post here my question to him:
<begins pm to owen>
hi Owen!
first of all, thanks for your efforts!
one question though, on my paypal (german/austrian version of the website) it asks if i want to send money to a friend or pay for some service or article.
which one should i choose? (i think the difference lies in the paypal fees)
cheers!
daniel
<ends pm to owen>
would any of you know which option to choose?
But do check what they reply (just before "send") and that the receiver actually gets the amount of money due.
alrighty!
thanks redjr and andrewT for the tips.
as we say in german: vorfreude ist die beste freude!
(loosely: cant wait for it to arrive!)
thanks redjr and andrewT for the tips.
as we say in german: vorfreude ist die beste freude!
(loosely: cant wait for it to arrive!)
Hey Owen -- for those of us who added our NTD1 orders to the spreadsheet after the 22nd, do you expect there to be a long wait, or do you have more than 50 boards in stock? Thanks!
I suppose...
That you are asking for a transformer recommendation for the NTD1 V3 power supply? Or are you planning on using other supplies and just looking for how many A capability you need?
I am interested in knowing the transformer(s) recommendation for the NTD1 V3 power supply....
perhaps 2 pieces of 30 VA around 28-30 volts?
That you are asking for a transformer recommendation for the NTD1 V3 power supply? Or are you planning on using other supplies and just looking for how many A capability you need?
I am interested in knowing the transformer(s) recommendation for the NTD1 V3 power supply....
perhaps 2 pieces of 30 VA around 28-30 volts?
Sabrosa:
Sorry... I missed your order on the sheet somehow. I have plenty of boards and will send you a payment request tonight!
damuffin:
I would suggest a pair of 50VA dual 32 VAC secondary transformers like these:
AS-0532 - 50VA 32V Transformer - AnTek Products Corp
Regards,
Owen
Sorry... I missed your order on the sheet somehow. I have plenty of boards and will send you a payment request tonight!
damuffin:
I would suggest a pair of 50VA dual 32 VAC secondary transformers like these:
AS-0532 - 50VA 32V Transformer - AnTek Products Corp
Regards,
Owen
It seems to be an error en the links on the first post, so I'm not able to figure out which is BAL-BAL and SE-SE, (or BAL-SE).
However text where the link points, stats "I needed a balanced input, and wanted to use a standard 1/4" jack for the output."
Which I think is what I like to have, using my DAC internal volume control.
So which amp version should I order ?
Or does there exist one option where I can switch between XLR or jack on the output ?
Specs of my DAC.
Output Impedance 20 Ohms.
Maximum Output Level 20 Vrms balanced.
Frequency Response 20 Hz-20 kHz, ± 0.025 dB, Ref. 1KHz.
THD+Noise Less than 0.0015% @ 1KHz, maximum output level.
Dynamic Range 105dB minimum, 20KHz bandwidth, Ref. 1KHZ, A-weighted.
Signal to Noise Ratio 105dB typical, idle channel, A-weighted.
Crosstalk-105dB Right - Left, >-120dB Center-Left @ 20KHz.
I have not got my headphone yet, but it's likely to have these specs:
IMPEDANCE 18 Ω
FREQUENCY RESPONSE (HEADPHONES) 16Hz - 22000Hz
SOUND PRESSURE LEVEL (SPL) 113dB (1 kHz/1 Vrms)
THD, TOTAL HARMONIC DISTORTION <0.5%
So it's not one of those high-end one with a input impedance of >300 ohm.
So my question is, do I need to change anything on the basic configuration in order to suit my needs (related to headphone impedance) ?
This guy seems to have a lot of opinions about headphone amps:
NwAvGuy: Headphone Amps/DACs Explained
And this one even made a calckulator :
https://robrobinette.com/HeadphoneResistorNetworkCalculator.htm
So that's why asking.
Is the PSU meant to be connected to 220 or 110 VAC, or am I missing something here ?
Can anyone supply me with link to (high quality) cabinets ?
Maybe with option to have my own made front.
Looking at some pics, it seems like the XLR and jack female is not part of the BOM. Is this correct ?
And I do not mind avoid the soldering. So is it possible to purchase a complete pcb ?
Or even a complete amp ?
When this is answerd I will place my order using the spreadsheet.
(As the prommissed website is not up an running yet I guess).
However text where the link points, stats "I needed a balanced input, and wanted to use a standard 1/4" jack for the output."
Which I think is what I like to have, using my DAC internal volume control.
So which amp version should I order ?
Or does there exist one option where I can switch between XLR or jack on the output ?
Specs of my DAC.
Output Impedance 20 Ohms.
Maximum Output Level 20 Vrms balanced.
Frequency Response 20 Hz-20 kHz, ± 0.025 dB, Ref. 1KHz.
THD+Noise Less than 0.0015% @ 1KHz, maximum output level.
Dynamic Range 105dB minimum, 20KHz bandwidth, Ref. 1KHZ, A-weighted.
Signal to Noise Ratio 105dB typical, idle channel, A-weighted.
Crosstalk-105dB Right - Left, >-120dB Center-Left @ 20KHz.
I have not got my headphone yet, but it's likely to have these specs:
IMPEDANCE 18 Ω
FREQUENCY RESPONSE (HEADPHONES) 16Hz - 22000Hz
SOUND PRESSURE LEVEL (SPL) 113dB (1 kHz/1 Vrms)
THD, TOTAL HARMONIC DISTORTION <0.5%
So it's not one of those high-end one with a input impedance of >300 ohm.
So my question is, do I need to change anything on the basic configuration in order to suit my needs (related to headphone impedance) ?
This guy seems to have a lot of opinions about headphone amps:
NwAvGuy: Headphone Amps/DACs Explained
And this one even made a calckulator :
https://robrobinette.com/HeadphoneResistorNetworkCalculator.htm
So that's why asking.
Is the PSU meant to be connected to 220 or 110 VAC, or am I missing something here ?
Can anyone supply me with link to (high quality) cabinets ?
Maybe with option to have my own made front.
Looking at some pics, it seems like the XLR and jack female is not part of the BOM. Is this correct ?
And I do not mind avoid the soldering. So is it possible to purchase a complete pcb ?
Or even a complete amp ?
When this is answerd I will place my order using the spreadsheet.
(As the prommissed website is not up an running yet I guess).
OPC - I bought the NTD1 not realizing it doesn't have unbalanced out. Is it possible to wire this up as unbalanced and still have 2VRMS output? Or is this balanced out only?
Not really...
The Buffalo DAC (and Acko) which the NTD1 is designed for is specifically a balanced output DAC, and the NTD1 is specifically a balanced I/V stage. You do not want to use just half of the DACs output, as this would reduce performance substantially.
To create a single ended output from the NTD1 there are two acceptable solutions:
1. Use an active balanced to single ended converter stage, such as Twisted Pear Audio's "Ballsie" (this is essentially the same circuit TPA uses on their IVY-III and Legato 3 I/V stages to produce the single ended output)
2. Or, you could use a pair of output transformers to create the single ended output.
Either one of the two above methods would preserve the high performance of the balanced circuit, basically they sum the balanced outputs into a single ended output.
Of course the best option is to pair the Buffalo/NTD1 with a balanced input amplifier...
The Buffalo DAC (and Acko) which the NTD1 is designed for is specifically a balanced output DAC, and the NTD1 is specifically a balanced I/V stage. You do not want to use just half of the DACs output, as this would reduce performance substantially.
To create a single ended output from the NTD1 there are two acceptable solutions:
1. Use an active balanced to single ended converter stage, such as Twisted Pear Audio's "Ballsie" (this is essentially the same circuit TPA uses on their IVY-III and Legato 3 I/V stages to produce the single ended output)
2. Or, you could use a pair of output transformers to create the single ended output.
Either one of the two above methods would preserve the high performance of the balanced circuit, basically they sum the balanced outputs into a single ended output.
Of course the best option is to pair the Buffalo/NTD1 with a balanced input amplifier...
Hi Mull3t,
Barrows is spot on in his answer. The entire system is designed to be balanced, and that's where performance is best. You can always take an SE output from one phase of the NTD1, but you'll lose about 20-30dB on the THD+N numbers. It's still respectable, but not world class.
I would generally suggest looking at an amplifier with balanced inputs, or barring that, consider using the BAL-BAL headphone amp as a balanced to SE converter. Taking one phase of the output of the BAL-BAL will give you full performance, and as an added bonus you can have a balanced headphone output.
I'll tackle R1200CL's comments in a different post.
Regards,
Owen
Barrows is spot on in his answer. The entire system is designed to be balanced, and that's where performance is best. You can always take an SE output from one phase of the NTD1, but you'll lose about 20-30dB on the THD+N numbers. It's still respectable, but not world class.
I would generally suggest looking at an amplifier with balanced inputs, or barring that, consider using the BAL-BAL headphone amp as a balanced to SE converter. Taking one phase of the output of the BAL-BAL will give you full performance, and as an added bonus you can have a balanced headphone output.
I'll tackle R1200CL's comments in a different post.
Regards,
Owen
The BAL-BAL is the best candidate for your application. You can feed it XLR on the input, and take a single-ended output from the positive phases of the balanced output to GND.
This reduces performance compared to a true balanced headphone system, and may increase click/pop/DC susceptibility.
I would strongly suggest converting your headphones to balanced input, and making a small 4" adapter cable to go back to 1/4" if you need backwards compatibility. It's easy and very low cost to do.
This could be easily implemented with a switch, or with a few relays, but you would be on your own with this since it's not a standard setup.
Nothing at all. The BAL-BAL is all set to drive any headphone impedance you can throw at it. By default, the gain is probably set just about right for your low impedance headphones.
He does have a lot of opinions, and I agree with him on absolutely everything from a technical perspective. His articles are very thorough, and he does a great job of explaining what the important aspects of a good headphone amplifier are. The only places I disagree with him is that I'm not willing to sacrifice quality for the price of a sandwich (he is very value driven, where I am more performance driven) and I'm more hesitant than he is to put limits on the capabilities of human hearing.
I suggest not doing this for many reasons:
- This setup results in higher noise than a good headphone amp
- It's wasteful
- Damping factor isn't good
- Resistor dissipation can be very high
- THD will be higher than a good headphone amp
You need to supply the transformer for the PSU, and almost all modern transformers have dual primaries that can be wired for 120V or 240V. All that matters to the supply is that it gets 10-12VAC at the inputs.
I can't help you here, but there are many threads on diyAudio that cover this topic. Do a search and you will find several great sources.
Correct. Everyone uses different connectors based on their application, so they are not included in the BOM. Some people will add this to an existing amplifier or chassis and may not require connectors at all. It's up to the end user to plan their chassis and connector requirements. Same applies to the power transformer. The BOM gets you fully populated boards and that's about it.
I don't have any, but someone on here might be willing to sell theirs or build you one.
Regards,
Owen
Thanks.
I suppose you already have noted my order on your spreadsheet.
Only one PSU needed pr. amp I suppose.
I will probably order missing items from Farnell. Elfa optional.
So if anyone have suggestions for transformer, etc.
Also I would need a good welding station. Any suggestion below $500 anyone. Hot air is best ?
I'm reading though the original The Wire thread. Still in 211. Page 75 of 241 at the moment. So hopefully I get some more tips how to do things during my reading.
The headphone I'm planning to use is the Sennheiser Momentum M2. According to Headphones: Full-Size, In-Ear, Wireless, Noise Cancelling, Bluetooth these can't be wired to balanced. Maybe I will have to reconsidder.
I like to have one that can be used with both my iPhone and my DAC in living room.
I suppose you already have noted my order on your spreadsheet.
Only one PSU needed pr. amp I suppose.
I will probably order missing items from Farnell. Elfa optional.
So if anyone have suggestions for transformer, etc.
Also I would need a good welding station. Any suggestion below $500 anyone. Hot air is best ?
I'm reading though the original The Wire thread. Still in 211. Page 75 of 241 at the moment. So hopefully I get some more tips how to do things during my reading.
The headphone I'm planning to use is the Sennheiser Momentum M2. According to Headphones: Full-Size, In-Ear, Wireless, Noise Cancelling, Bluetooth these can't be wired to balanced. Maybe I will have to reconsidder.
I like to have one that can be used with both my iPhone and my DAC in living room.
Last edited:
NTD1
This morning I started soldering the SMD parts and I've noticed that we are missing parts from the PSU BOM it looks like a decoupling cap on the L49880.
C21-24.
https://docs.google.com/spreadsheets/d/1NlmVzlrqDlmcYsFNG7cJrGvChL_2aE4W8IJgPMz_KuI/edit?pli=1#gid=0
This morning I started soldering the SMD parts and I've noticed that we are missing parts from the PSU BOM it looks like a decoupling cap on the L49880.
C21-24.
https://docs.google.com/spreadsheets/d/1NlmVzlrqDlmcYsFNG7cJrGvChL_2aE4W8IJgPMz_KuI/edit?pli=1#gid=0
Attachments
Hi damuffin,
Looks like a good start!
Those caps (C21-C24) are meant to be left empty. They are the "soft start" caps (Css) for the ADP7142.
I originally had 1uF parts in there to slow down the startup, but I found the supply prone to locking up with them populated.
Seems to work best with no caps in that location at all.
It should also be noted that power sequencing with the new supplies is critical. The power supply needs to come up before, or at the same time as the DAC board itself. Powering up the DAC first and then the I/V supply can sometimes lead to supply lockups.
Regards,
Owen
Looks like a good start!
Those caps (C21-C24) are meant to be left empty. They are the "soft start" caps (Css) for the ADP7142.
I originally had 1uF parts in there to slow down the startup, but I found the supply prone to locking up with them populated.
Seems to work best with no caps in that location at all.
It should also be noted that power sequencing with the new supplies is critical. The power supply needs to come up before, or at the same time as the DAC board itself. Powering up the DAC first and then the I/V supply can sometimes lead to supply lockups.
Regards,
Owen