Glad to hear about your wife Regal!
About the pcb/kits I would be interested in 2 of them... I will be happy with the best ones.
Brgds
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A capital(ist's) idea
I am beginning to understand how qusp became the curmudgeon we know and love.
>>About the pcb/kits I would be interested in 2 of them... I will be happy with the best ones.
There are four separate boards that were produced. If enough fanatics agreed on a particular board and were willing to pay in advance for a specific pcb (not '2 of the best'), then one MIGHT get etched but kits require an inordinate effort on the part of whoever runs the GB.
My recommendation would be for some fanatic with extra time to start a GB thread (if opc would agree) and see if there is sufficient demand to break even on the production of another batch.
Personally I think opc hit a home run and ought to capitalize on it. I am building a JC-80 currently. It requires two pcbs (US$40 shipped) and hours of matching, etc. so I think a price of $45 for the BAL-BAL would be entirely justified and possibly bring supply and demand into balance.
I am beginning to understand how qusp became the curmudgeon we know and love.
>>About the pcb/kits I would be interested in 2 of them... I will be happy with the best ones.
There are four separate boards that were produced. If enough fanatics agreed on a particular board and were willing to pay in advance for a specific pcb (not '2 of the best'), then one MIGHT get etched but kits require an inordinate effort on the part of whoever runs the GB.
My recommendation would be for some fanatic with extra time to start a GB thread (if opc would agree) and see if there is sufficient demand to break even on the production of another batch.
Personally I think opc hit a home run and ought to capitalize on it. I am building a JC-80 currently. It requires two pcbs (US$40 shipped) and hours of matching, etc. so I think a price of $45 for the BAL-BAL would be entirely justified and possibly bring supply and demand into balance.
I see, the BAL-BAL are the best ones so if there is to be another GB count me in for 2 pcb's/kits(matched of course)
.Brgds
There is no hope for the principled man
Heh. Those prices would be for pcbs only, but should you receive unmatched pcbs that would be grounds for complaint.
I believe BAL-BAL represents the best value as either balanced or se signals can be fed into the beastie -- the only requirement being recabling most headphones. The BAL-SE relaxes even that requirement but with some additional complexity.
AFAIK the BAL-SE boards are still available at the almost insane price of CDN$12 each.
Heh. Those prices would be for pcbs only, but should you receive unmatched pcbs that would be grounds for complaint.
I believe BAL-BAL represents the best value as either balanced or se signals can be fed into the beastie -- the only requirement being recabling most headphones. The BAL-SE relaxes even that requirement but with some additional complexity.
AFAIK the BAL-SE boards are still available at the almost insane price of CDN$12 each.
Now...
What the heck are you trying to sell to me? Send me a couple of BAL-BAL to a reasonable price if available with a BOM and instructions of what components I need to match. I won't be able to pay before the 9'th of Jan...
Brgds
Heh. Those prices would be for pcbs only, but should you receive unmatched pcbs that would be grounds for complaint.
I believe BAL-BAL represents the best value as either balanced or se signals can be fed into the beastie -- the only requirement being recabling most headphones. The BAL-SE relaxes even that requirement but with some additional complexity.
AFAIK the BAL-SE boards are still available at the almost insane price of CDN$12 each.
What the heck are you trying to sell to me? Send me a couple of BAL-BAL to a reasonable price if available with a BOM and instructions of what components I need to match. I won't be able to pay before the 9'th of Jan...
Brgds
I never tried intended to sell anything and I cannot understand how you thought otherwise. I am a buyer, not a seller. opc does ALL the selling on this thread.
If you really want to build a wire the only route that may be available is the BAL-SE. If that will drive your headphones you should be all set.
If you really want to build a wire the only route that may be available is the BAL-SE. If that will drive your headphones you should be all set.
I've had a change in my financial outlook. Since I've already got the bal-se boards I'm thinking about compromising on the DAC I was going to put into the build I was doing for my 2nd amp (intended as a gift), some of the DAC options I'm looking at now offer only se output.
Is there any reason why I can't just feed an SE signal into the +/gnd inputs on the bal-se?
I have not tested that but AFAIK it ought to. SE-SE is four LME49990s cheaper however.
lol indeed. At the start I thought it was a case of not reading the thread and immediately thought of you, qusp
Then it seemed he was joking but I now believe something was 'lost in translation' and he seriously thought some 'capitalist' was selling hundred dollar bags of unobtaniums, matched no less, for forty five. I'd take two helpings of that deal from the buying side too.
It takes me back to our discussion of how easily confusing this can become for those whose native language is not English. I do feel badly about the 'exchange' and will be less ready to joke around when a post seems to be coming out of the blue.
This insomniac needs to head to bed lest he be seriously taken to be proposing another money losing proposition. The syntax of the previous sentence makes even my head ache.
depends how much you trust the common mode matching of 'the wire' channels (by design, with 0.1% resistors it should be very good). i often use the sabre direct with 3.6/2vdc (i run higher AVCC) and with a well made cable to help cancel common mode DC error its fine, but there is a risk, however slight that there might be some problem with a power supply that pulls the output to one of the rails., unless you were really cranking them, 3.3v/2 is going to be less harmful than 5v/2.
personally i think its fine, the headphone doesnt have a ground connection and bal/bal is only unity gain so if theres a fault, the most it will see is AVDD/2 and particularly with your hd600 this isnt going to cause any problems. added to that the input stage of the bal-bal is a differential opamp, so if one of the rails fails it will simply cease to function i would think. theres not a lot of rail capacitance to keep it going either.
all the same, if you can run on 3v3, why not do that?
personally i think its fine, the headphone doesnt have a ground connection and bal/bal is only unity gain so if theres a fault, the most it will see is AVDD/2 and particularly with your hd600 this isnt going to cause any problems. added to that the input stage of the bal-bal is a differential opamp, so if one of the rails fails it will simply cease to function i would think. theres not a lot of rail capacitance to keep it going either.
all the same, if you can run on 3v3, why not do that?
no problem guys, some other factors to consider that apply in non-standard builds primarily. the AC signal will by riding on top of the DC voltage, thus DC offset. this means that any music signal will swing that far closer to the rails, so a 2vac signal will sit AVDD/2 higher; since the rails in this case sit quite a lot further out than any direct signal from the dac will give, there is no chance of clipping, but if you are running lower rails it might. also if you apply gain in the VAS, the DC offset will be multiplied by that.
@hochopeper: so you are still running balanced headphones? if you are running dual mono with a balanced input into each bal-se wire, I would think the common mode offset will be cancelled in the instrumentation amp before the buffers, so nothing to worry about. even without that if running balanced headphones you will have the same safeties i mentioned above to Wolfsin, as long as the DC error is common to both phases its cancelled given the channels match well; in fact it would take a pretty serious mismatch to cause an issue at unity gain.
@hochopeper: so you are still running balanced headphones? if you are running dual mono with a balanced input into each bal-se wire, I would think the common mode offset will be cancelled in the instrumentation amp before the buffers, so nothing to worry about. even without that if running balanced headphones you will have the same safeties i mentioned above to Wolfsin, as long as the DC error is common to both phases its cancelled given the channels match well; in fact it would take a pretty serious mismatch to cause an issue at unity gain.
Bluehaze alert
Hate to tell you this hochopeper but if that's the case we are both in a world of hurt Thanks for the PM. We are progressing down the same path. If you do something that smokes, please pm or post immediately!
I think Russ & Brian were answering based on what ought to happen. qusp only considered what could go wrong (that is consistent with the curmudgeon world view). Since the gain is 1, with AVDD at 3.3v the output would seem pretty low but then I took a careful look at both datasheets. I am using the 8740 and it seems to suggest a preference for AVDD=DVDD whereas the 8741 shows typ voltages that would put DVDD at 3.3 and AVDD at 5v. The Opus BOM specifies no quantity for either the 3.3 or 5v part and no correspondence is spec'ed wrt VRD and VRA, possibly because Opus allows either DAC to be used.
Given the part I am using, the wise counsel of qusp, and my well earned distaste for clouds of blue smoke, I will initially run both voltages at 3.3v
Hate to tell you this hochopeper but if that's the case we are both in a world of hurt
Thanks for the PM. We are progressing down the same path. If you do something that smokes, please pm or post immediately! I think Russ & Brian were answering based on what ought to happen. qusp only considered what could go wrong (that is consistent with the curmudgeon world view). Since the gain is 1, with AVDD at 3.3v the output would seem pretty low but then I took a careful look at both datasheets. I am using the 8740 and it seems to suggest a preference for AVDD=DVDD whereas the 8741 shows typ voltages that would put DVDD at 3.3 and AVDD at 5v. The Opus BOM specifies no quantity for either the 3.3 or 5v part and no correspondence is spec'ed wrt VRD and VRA, possibly because Opus allows either DAC to be used.
Given the part I am using, the wise counsel of qusp, and my well earned distaste for clouds of blue smoke, I will initially run both voltages at 3.3v
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hey i wasnt saying to do it either way, either should be fine, but if there is no good reason to run it higher why would you? the TP guys have rose coloured glasses when it comes to their products and view modifications to them with disdain; i simply mentioned possible problems to look out for that would apply to any dac that has DC on the output when used with a DC coupled amp. i do it myself without any problems, but there are problems that can present that should be ruled out before you connect headphones
i know that others apart from you 2 will read my replies, possibly using a similar, but not the same dac and amp; so i would rather cover all bases and my *** by being thorough.
if all goes well theres nothing stopping you from changing the supply voltages later is there?
i know that others apart from you 2 will read my replies, possibly using a similar, but not the same dac and amp; so i would rather cover all bases and my *** by being thorough.
if all goes well theres nothing stopping you from changing the supply voltages later is there?
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Bitz->Voltz->'the wire'->canz
qusp, buddy, you are my guiding light. Seriously. I had not considered how many ways my senns might be made to glow. I did balance wire some Sonys to take the first of the worst but that is why I asked the question. Your answer was JUST what I needed. I can see no reason for not using 3.3v, possibly permanently, but swapping VRA is hardly brain surgery.
Eventually I plan to head down the hochopeper highway with a pair of dual mono opuses (s.b. opii?) feeding a BAL-SE bridged across the HD600s. That will provide the minimalist, cap free, filter free test bed alternative to the quad BB1704s on which I can perform trials and listening tests. I will be happy to know I am not the only traveler out there but would rather follow hochopeper's tail lights than blaze a trail.
It is interesting that Russ is about to release an Opus redesign just as I am finally populating the first of my Opus pcbs. I will try to draft behind hochopeper as we begin to pick up speed. I will be using CPUstick initially to control the 8740 in software mode. It was developed by two friends, Rich Testardi and Greg Thelen, and facilitates rapid prototyping using BASIC. What are your control plans hochopeper?
BTW, if anybody has finished another wire, please interrupt this semiOT chatter with some news!
qusp, buddy, you are my guiding light. Seriously. I had not considered how many ways my senns might be made to glow. I did balance wire some Sonys to take the first of the worst but that is why I asked the question. Your answer was JUST what I needed. I can see no reason for not using 3.3v, possibly permanently, but swapping VRA is hardly brain surgery.
Eventually I plan to head down the hochopeper highway with a pair of dual mono opuses (s.b. opii?) feeding a BAL-SE bridged across the HD600s. That will provide the minimalist, cap free, filter free test bed alternative to the quad BB1704s on which I can perform trials and listening tests. I will be happy to know I am not the only traveler out there but would rather follow hochopeper's tail lights than blaze a trail.
It is interesting that Russ is about to release an Opus redesign just as I am finally populating the first of my Opus pcbs. I will try to draft behind hochopeper as we begin to pick up speed. I will be using CPUstick initially to control the 8740 in software mode. It was developed by two friends, Rich Testardi and Greg Thelen, and facilitates rapid prototyping using BASIC. What are your control plans hochopeper?
BTW, if anybody has finished another wire, please interrupt this semiOT chatter with some news!
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If you're looking to follow my lights, I hope you're not in a hurry! I'm a way off starting just yet. PCBs will arrive next week but I have no PSU for the DAC or The Wires yet. Eventually I'll be building 2 different 'Wires' setups one feeding on the signal from 8741 dual mono (opus) the other from a yet to be determined dac, possibly PCM27xx based dac (hence single-ended into bal-se questions yesterday).
I have a spare arduino or two (arduinii!?) sitting here so I'll likely have a hack at the code that glt from this forum wrote for controlling his opii minions before he moved his 'hifiduino' code to target ESS DACs.
Thanks qusp for clarifying about the interaction of dc coupling DAC outputs to the wire. My 'phones are wired as they were at the factory (SE) at present, that's sure to change though!
I have a spare arduino or two (arduinii!?) sitting here so I'll likely have a hack at the code that glt from this forum wrote for controlling his opii minions before he moved his 'hifiduino' code to target ESS DACs.
Thanks qusp for clarifying about the interaction of dc coupling DAC outputs to the wire. My 'phones are wired as they were at the factory (SE) at present, that's sure to change though!