I am about to finalize concept and design for basically a complete amp stage 'between' the balanced voltage output of my DAC (Wolfson WM8741 in dual mono config) and my headphones with 8ohm impedance (Ultimate Ears UE-10pro). Credtis for this go to Lars/revintage who has provided immense knowledge and support - thank you so much Lars!!
The specifics are:
- Lundahl LL1676 transformers (connected 2:1) for balanced-to-unbalanced conversion
- two parallelled E182CC/channel as in the attached schematic
- Lundahl LL1630 output transformers
What do you all think of this? I am absolutely thrilled by how 'simple' and straightforward this is, a purist and minimalist approach with highest-quality components - I'd appreciate your comments if you'd like to share
Best,
Robert
The specifics are:
- Lundahl LL1676 transformers (connected 2:1) for balanced-to-unbalanced conversion
- two parallelled E182CC/channel as in the attached schematic
- Lundahl LL1630 output transformers
What do you all think of this? I am absolutely thrilled by how 'simple' and straightforward this is, a purist and minimalist approach with highest-quality components - I'd appreciate your comments if you'd like to share
Best,
Robert
Attachments
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I would steal his powersupply: ecp.cc
Look also here: http://www.audiodesignguide.com/NewHeadphoneAmp/index.html
Look also here: http://www.audiodesignguide.com/NewHeadphoneAmp/index.html
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Hi Jaap,
many thanks!
I knew the ecp.cc article, shurely an interesting and integrating solution.
The audiodesignguide article was very interesting reading too, I could find additional thoughts on the Lundahls, and on many other aspects
Well, regarding power supply I was intending more to keep it 'external' - I was thinking of this: Z100A shunt Voltage Regulator in combination with this: CCS1A Constant Current Source Would this work - or is it blasphemy...?
Many Thanks,
Robert
many thanks!
I knew the ecp.cc article, shurely an interesting and integrating solution.
The audiodesignguide article was very interesting reading too, I could find additional thoughts on the Lundahls, and on many other aspects
Well, regarding power supply I was intending more to keep it 'external' - I was thinking of this: Z100A shunt Voltage Regulator in combination with this: CCS1A Constant Current Source Would this work - or is it blasphemy...?
Many Thanks,
Robert
Hey Bertel,
Waste of money! With discrete components you can build a PSU for this amp at a fraction of the cost. One or two depletion MOSFETS and a voltage regulating tube(plus a few small components) is all that is needed. Two channels will draw 40mA plus the 10-15mA through the regulator.
Waste of money
! With discrete components you can build a PSU for this amp at a fraction of the cost. One or two depletion MOSFETS and a voltage regulating tube(plus a few small components) is all that is needed. Two channels will draw 40mA plus the 10-15mA through the regulator.
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Ok, got that
What do you think of the PSU which is pictured in the second link that Jaap had linked to (Hi-end headphone amplifier, bit down the page) ? I shy away a bit from "integrating" it as much as in the epc.cc example - or would this bring benefits not achievable with an "external" solution?
Thanks
Robert
What do you think of the PSU which is pictured in the second link that Jaap had linked to (Hi-end headphone amplifier, bit down the page) ? I shy away a bit from "integrating" it as much as in the epc.cc example - or would this bring benefits not achievable with an "external" solution?
Thanks
Robert
Hi Jaap,
Well, regarding power supply I was intending more to keep it 'external' - I was thinking of this: Z100A shunt Voltage Regulator in combination with this: CCS1A Constant Current Source Would this work - or is it blasphemy...?
Many Thanks,
Robert
I have done a 5814 (also D3A or E810F)/LL1630 pre-amp in the same style. First with 2 chokes in the psu and later with only one choke + 10M45s CCS + 0A2 gas tube returned to the cathode. This was a big step forward (more bass for instance). I had not enough room so I tie wrapped the 0A2 under the hood. It worked a long time but the thing started oscillating yesterday so I have to do some surgery.
I am also thinking of changing the PSU by adding a solid state regulator and perhaps taking the 0A2's out. If I remove two big oil caps I have room again on the chassis.
I have some boards from the Jan Didden (Janneman)/Elektor regulator. Take a look at the power supply forum. There is a choice these days. I saw for instance the simplistic Salas regulator. I even think that for a hobbyist a HV superregulator is not over the top. Provided that you are not ripped off by buying a too expensive kit
Ah, so you had the 0A2 connected back to the cathode like in the ecp.cc example, right? I don't know, well sure I have no experience with tube-based PSUs, but I would really like to keep PSU 'out' and go solid state too.
And yes, good that you mention it - I am just about to start building two shunt regulators as designed by ikoflexer, this is further development based on the simple Salas reg
And yes, good that you mention it - I am just about to start building two shunt regulators as designed by ikoflexer, this is further development based on the simple Salas reg
well I have one question, why not keep it balanced the whole way?? if your doing all this, you should be able to whack a balanced cable on the UE-10?? I certainly know that my JH13 sound far superior to even their normal uber self when run balanced out of my Buffalo32. you can even buy small differential connectors from neutrik or or ODU (available in male and female/inline and chassis mount) that will allow you to use them balanced at home and use a small and light adapter to run single ended when portable. i'm quite interested in your results actually. I have been playing with the idea of a tube stage in my acko dac build. i'm using twisted pear and sjorstromaudio regs, some nice iron and i'm torn between a straight transformer coupled output, a tube buffer with transformer output; or the new D1B1 balanced buffer to partner with the dac. the idea being to drive the JH13 directly as one option, and the ability to also drive my active monitors; perhaps through a different buffer stage switched via relay, or the second signal pulled from a different point in the circuit if necessary
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Well, I will follow the balanced-all-the way-through path in my alternative solid state approach - ZAPfilter MK2 when it comes out in Jan and then some kind of diamond buffer or so, don't know yet.
This approach here is kind of the other extreme, a serious implementation with transformers and tubes, I love that too, and I feel this fits me better single-ended ;-)
BTW: You mention
And: I had missed the D1B1 - now that sounds interesting, probably will have to give that a try too ;-) Thanks for pointing me to it!
This approach here is kind of the other extreme, a serious implementation with transformers and tubes, I love that too, and I feel this fits me better single-ended ;-)
BTW: You mention
- these are for the output stage / chassis and not for the phones, right? Because this little pain has stopped me yet from already trying the UEs balanced - couldn't find those tiny connector pins...
And: I had missed the D1B1 - now that sounds interesting, probably will have to give that a try too ;-) Thanks for pointing me to it!
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yeah i'll probably end up playing with some of the tiny little smd diamond buffers I picked up from pers as well (SSB01) thats the alternative; transformer direct to the power monitors and buffered to the IEMs
sure, whatever floats you boat, it takes some serious dedication to run them balanced, but it doesnt have to be as painful as many think, the lundahs I have in mind will spin bal and SE, as will the buffers
yes those are for the chassis and termination at the end of the cable, the IEM connectors you only have 2 options for DIY, reterminate a stock cable with the connectors and put a matching female on the chassis, or make the IEM connectors yourself as I have with plastic molding and sterling silver pins
you cannot buy the connectors, you must solder the pins on and add the molding to the finished cable with memory wire, which as it happens its pure silver as well, twas the only suitable gauge wire I had on hand, nothing fancy, just soft annealed german silver, only 60c a foot or something .are you doing the ackodac as well?? yeah the D1B1 is in the lead at the monent, but there is something full-on but at the same time elegant about a transformer coupled/tube buffered output dac.
Hmm, that's probably what I'll have to do as well.. Let's see - single ended transformer-tube-combo first, stil enough work needed here to finalize the design
That's exactly what floats my boat with this here
No, I have two Buffalo32s already (one not working properly, thus for testing mods
), waiting for the reworked new version to become available which will be fully tweakable, including all registers and firmware accessible Besides that, I'm currently kind of on a reverse path - have to implement all of others finest and greatest: Wolfson WM8741 in the works, BB PCM1794A to follow, then aybe the AD1955, but also two NOS DACs, namely TDA1541A and PCM1704, or maybe rather the TDA1543 - *sigh* this winter will be tough... 
well if you are confident making your own cable, you can send it here and i'll terminate it for you if you like. perhaps best via PM
ditto, thus the reason I was quite interested to see what was in this threadThat's exactly what floats my boat with this here
errm.. you do realize that the ackodac is a sabre dac based on the same chips as the buffalo32?? I have a buffalo32 as well (includiong both types of power supply), but I grew tired of waiting for the TP guys to release the tweakers board; plus the ackodac has all the things the next generation of the buff is going for, well all bar the fully developed micro (under development), which will be finished well before the next incarnation of the buffalo. It has all the ins and outs exposed on pads ready for molex or pin headers; along with all the regulation points with pads directly next to the components that are to be regulated. the BOM uses higher speced parts (COG instead of X7R and decoupling with organic polymer caps; its also about half the price including all parts. (just dac board, not regs or PSU or I/V). plus the D1B1 is to be released in a form that is specifically designed to stack directly on top of it, or something like you mention could easily be substituted. funny though, i've been doing something similar for kicks whike I wait, right down to the TDA1541A dac not doing a PCM1704 or AD1955 though. PM me if you want more details.No, I have two Buffalo32s already (one not working properly, thus for testing mods
so I reckon you should get on board, theres no reason to hang around waiting for the TP guys to release it and you'll save youreslf some time and money in the process. BTW I have no affiliation with Acko bar being involved in the shaping of it via feedback and I might be trying my hand at developing a transformer based output module to round out the compliment of options.
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acko DAC
I DID realize that the acko DAC is based on the ESS90XX, but I DID NOT realize that it seems to be designed the way I'm looking for: I hate the 'integrated' nature of the current Buffalo32 version but instead build e.g. my current Wolfson WM8741 based DAC with as little around the chip as possible (currently on its board there's only six caps, plus the regulators as close as possible, plus a few components aside to tap into the software options, but nothing in the signal path from the chip to the transformer). I will have a thorough look at the acko DAC concept if this is similar (or if I can adjust it accordingly), and yes the micro is important too.
If this all is the case - yes, then you definitely have me on board I'll PM you.
I DID realize that the acko DAC is based on the ESS90XX, but I DID NOT realize that it seems to be designed the way I'm looking for: I hate the 'integrated' nature of the current Buffalo32 version but instead build e.g. my current Wolfson WM8741 based DAC with as little around the chip as possible (currently on its board there's only six caps, plus the regulators as close as possible, plus a few components aside to tap into the software options, but nothing in the signal path from the chip to the transformer). I will have a thorough look at the acko DAC concept if this is similar (or if I can adjust it accordingly), and yes the micro is important too.
If this all is the case - yes, then you definitely have me on board
I'll PM you.- Status
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