I strongly agree with jam. The preamp has to have balanced outputs. For some people that would be the only use from it - converting single ended to balanced (SOZ and X series amps). And when you have balance outputs it would be a waste not to include balanced inputs.
What about phono section? Do you want to include it? I would rather suggest separate module which would be an option to anybody interested.
Separete power supply? Battery operation? AC power regeneration?
What about phono section? Do you want to include it? I would rather suggest separate module which would be an option to anybody interested.
Separete power supply? Battery operation? AC power regeneration?
project managers suck!
haha, j/k.. i have had PMs and they are ok i guess.
but as harry alludes to, sometimes they can be a royal pain in the...
3 people developing software w/o a manger is fine if one of them really knows what they are doing, then they can manage themselves. problem is, 99% of people are not capable of managing themselves (me included probably)... so yeah, i guess they need a manager of some sort...
we will be building things as modules, so i expect things to be pretty flexible in terms of development and prototyping. i'm imagining an 8 chassis design - central control unit, 6 single-channel preamp units, and a big power supply box. for those who only need 2 channels, that would be only 4 chassis obviously. ideally, the actual signal modules should be very compact - i'm planning to use very low-profile, compact chassis for it.
i am OK with balanced ins/outs only if it does not significantly complicate the design. i would probably never use the balanced inputs but maybe the balanced outputs.
no phono! read my earlier post. consider the primary source material to be multichannel SACD, and it will also be integrated into a home theater system. actually with this project i'm trying to fill a void in high-quality multi-channel preamps on the market. there are plenty of good 2-channel units but other than those gross surround sound preamps i've seen very few multichannel units.
as i said, the power supply is a separate module, but it should be conventional AC-powered. another requirement of this "modern" design is that it be eminently convenient and usable. ok so maybe having 8 chassis is not very "convenient" but everything else about it should be.
cheers,
marc
haha, j/k.. i have had PMs and they are ok i guess.
but as harry alludes to, sometimes they can be a royal pain in the...3 people developing software w/o a manger is fine if one of them really knows what they are doing, then they can manage themselves.
problem is, 99% of people are not capable of managing themselves (me included probably)... so yeah, i guess they need a manager of some sort...we will be building things as modules, so i expect things to be pretty flexible in terms of development and prototyping. i'm imagining an 8 chassis design - central control unit, 6 single-channel preamp units, and a big power supply box. for those who only need 2 channels, that would be only 4 chassis obviously. ideally, the actual signal modules should be very compact - i'm planning to use very low-profile, compact chassis for it.
i am OK with balanced ins/outs only if it does not significantly complicate the design. i would probably never use the balanced inputs but maybe the balanced outputs.
no phono! read my earlier post.
consider the primary source material to be multichannel SACD, and it will also be integrated into a home theater system. actually with this project i'm trying to fill a void in high-quality multi-channel preamps on the market. there are plenty of good 2-channel units but other than those gross surround sound preamps i've seen very few multichannel units.as i said, the power supply is a separate module, but it should be conventional AC-powered. another requirement of this "modern" design is that it be eminently convenient and usable. ok so maybe having 8 chassis is not very "convenient" but everything else about it should be.
cheers,
marc
ok back to the preamp...
back to requirements. here is an updated list...
- solid state line stage, no phono
- traditional AC power supply in separate chassis
- DC coupled
- balanced outputs, optional balanced inputs
- minimum 10V RMS unbalanced output drive capability w/low distortion into 10k load; 5V RMS into 600 ohm load
- stability into capacitive loads
- HF response at least -3dB @100kHz
- possibly implemented with SMT devices
- each channel will be a separate module
- must have a digitally-controlled attenuator with at least 1dB resolution over a 70dB range
- microprocessor-based controller in separate chassis
in case you're wondering, most of those specs came off the top of my head, feel free to suggest adjustments.
cheers,
marc
back to requirements. here is an updated list...
- solid state line stage, no phono
- traditional AC power supply in separate chassis
- DC coupled
- balanced outputs, optional balanced inputs
- minimum 10V RMS unbalanced output drive capability w/low distortion into 10k load; 5V RMS into 600 ohm load
- stability into capacitive loads
- HF response at least -3dB @100kHz
- possibly implemented with SMT devices
- each channel will be a separate module
- must have a digitally-controlled attenuator with at least 1dB resolution over a 70dB range
- microprocessor-based controller in separate chassis
in case you're wondering, most of those specs came off the top of my head, feel free to suggest adjustments.
cheers,
marc
I agree with the direction this is taking. The multichannel angle is a niche that needs filling. If it is modular, one can make as many channels as one wants. The most interesting part is the digitally controlled volume/ channel balance module. IN FACT, I would suggest concentrating on that at the moment. In a world where
rotary switched discrete resistor controls are hundreds of dollars, and there are some really cool digital designs like the Pass, Rowland? etc, it would be great to have a modular volume control project with boards and clear instructions for ignorant folks as myself. A programable controller to control multi channels- with remote-how cool is that?!
MArk
rotary switched discrete resistor controls are hundreds of dollars, and there are some really cool digital designs like the Pass, Rowland? etc, it would be great to have a modular volume control project with boards and clear instructions for ignorant folks as myself. A programable controller to control multi channels- with remote-how cool is that?!
MArk
exactly - "cool" is what i'm looking for. the typical DIY way to do things is usually the "ghetto" route, with super-simple circuits, minimal controls, often no chassis to speak of. i'm looking to take the best of those ideas and integrate them into a very slick, polished product... an approach almost approaching industrial design in some respects. yes it goes against the grain of a lot of DIYers but i believe a synergistic realization is possible. just look at the Pass gear - beautiful product design with great circuitry. let's try to keep the engineering content as high as possible without forgetting our ghetto roots.
p.s. HPotter, i too need this for my home theater setup... i live in a NYC apartment and i don't have the luxury of separate music and movie systems. so i'm trying to find a versatile solution, thus my impetus for this project. it CAN be done!!!
p.p.s. mark, i believe the Rowland preamp uses a Crystal IC that i've ruled out as too mediocre for the project, so the Pass design is what we're striving for.
the typical DIY way to do things is usually the "ghetto" route, with super-simple circuits, minimal controls, often no chassis to speak of. i'm looking to take the best of those ideas and integrate them into a very slick, polished product... an approach almost approaching industrial design in some respects. yes it goes against the grain of a lot of DIYers but i believe a synergistic realization is possible. just look at the Pass gear - beautiful product design with great circuitry. let's try to keep the engineering content as high as possible without forgetting our ghetto roots. p.s. HPotter, i too need this for my home theater setup... i live in a NYC apartment and i don't have the luxury of separate music and movie systems. so i'm trying to find a versatile solution, thus my impetus for this project. it CAN be done!!!
p.p.s. mark, i believe the Rowland preamp uses a Crystal IC that i've ruled out as too mediocre for the project, so the Pass design is what we're striving for.
Let's concentrate on what's needed
I live in a San Francisco flat. Can you visualize "convergance of audio/video/computer?
OK you guys subtly bragging about your coding skills:
How about a USB interface to control it with your comp? LAter weadd the room measurement software an mikes.
I submit that these are actual needs in the DIY audio world:
1. A DIP header on a wire so the module can be used to replace the output op amps in your disk player? I've only seen commercial products for this so far... and they need installation- so why not do it all ourselves? People can post their experiances with various players. If the op amp is replaced with a preamp module that has adaquate gain, the passive preamp debate is moot: we would have the best of both worlds.
2. The afore mentioned digital level control.
I live in a San Francisco flat. Can you visualize "convergance of audio/video/computer?
OK you guys subtly bragging about your coding skills:
How about a USB interface to control it with your comp? LAter weadd the room measurement software an mikes.
I submit that these are actual needs in the DIY audio world:
1. A DIP header on a wire so the module can be used to replace the output op amps in your disk player? I've only seen commercial products for this so far... and they need installation- so why not do it all ourselves? People can post their experiances with various players. If the op amp is replaced with a preamp module that has adaquate gain, the passive preamp debate is moot: we would have the best of both worlds.
2. The afore mentioned digital level control.
sorry, that sounds a little out of scope.
er... i'm ok with the audio/video part, but computer? i'd rather leave my PCs out of it...
that sounds like an entire project in itself. a neat idea, but we are just trying to make a standalone purist, remote-control pre-amp. room measurements etc. are a separate matter. why would we need a USB port when i will have a very nice menu-driven front panel interface anyway?
again, an entirely different project. we are making a preamp, not cd player mods.
cool ideas, but not really what i was originally envisioning...
er... i'm ok with the audio/video part, but computer? i'd rather leave my PCs out of it...
that sounds like an entire project in itself. a neat idea, but we are just trying to make a standalone purist, remote-control pre-amp. room measurements etc. are a separate matter. why would we need a USB port when i will have a very nice menu-driven front panel interface anyway?
again, an entirely different project. we are making a preamp, not cd player mods.
cool ideas, but not really what i was originally envisioning...
oh yeah of course there will be a master volume. sorry lemme clarify. everything is done in software, there will be an rotary optical encoder on the control unit that by default is the master volume. you can also enter a menu mode where individual channels can be trimmed (separate memories for each input). make sense?
Well a decent rotary optical encoder is rather expensive ....
digital control has it's place but i think you should consider a slightly more minimalistic aproach to some segments of the design.
I'm sure Harry and Jocko just love the idea of a completely digitally controlled preamp (kidding) seriously, the clock related problems are a major concern.
digital control has it's place but i think you should consider a slightly more minimalistic aproach to some segments of the design.
I'm sure Harry and Jocko just love the idea of a completely digitally controlled preamp (kidding) seriously, the clock related problems are a major concern.
i'm a little concerned with digital noise radiation but i think i'll be able to handle it. i will have all control circuitry in a separate chassis with optocouplers to isolate the control lines. i intend to have only asynchronous digital logic around the audio circuits, no clock signals in the area. i think it can be done without too much problem. i don't think optical encoders are that expensive either, i see some decent ones at digikey for $50.
i know of no other way to accomplish the control flexibility i desire than with microprocessor control (even the Pass X preamps need it). i certainly don't intend to manually control 6 pots at once... hell, i can't even stand dual mono. there will be plenty of room for minimalism with the signal path (i definitely consider myself still in the less-is-more purist camp with the rest of you) but i don't see anything wrong with sophisticated control circuitry as long as it doesn't interfere with the signal. harry, jocko, and others may not like it but that's why they build their gear and i build mine.
cheers,
marc
i know of no other way to accomplish the control flexibility i desire than with microprocessor control (even the Pass X preamps need it). i certainly don't intend to manually control 6 pots at once... hell, i can't even stand dual mono. there will be plenty of room for minimalism with the signal path (i definitely consider myself still in the less-is-more purist camp with the rest of you) but i don't see anything wrong with sophisticated control circuitry as long as it doesn't interfere with the signal. harry, jocko, and others may not like it but that's why they build their gear and i build mine.
cheers,
marc
OK lets leave the computers out of it. I didn't realize that there would be a readout.
A rotary encoder looks pretty cheap compared to lots of rotary switches with discrete resistors
Why don't you reconsider the direct connection to the CD/DVD player though? It's pretty funny to read the discussions about passive preamps, which are really discussions of how the op amp in their player sounds. Think about it- what is the point of having an amp in the player AND another in the preamp? I thought this was a chance to improve the status quo.
It's not a CD player mod- its a preamp done right!!!
A rotary encoder looks pretty cheap compared to lots of rotary switches with discrete resistors
Why don't you reconsider the direct connection to the CD/DVD player though? It's pretty funny to read the discussions about passive preamps, which are really discussions of how the op amp in their player sounds. Think about it- what is the point of having an amp in the player AND another in the preamp? I thought this was a chance to improve the status quo.
It's not a CD player mod- its a preamp done right!!!
Variac said:
because then it is no longer a preamp.
this needs to be a separate component, period. it can not have any dependencies on other components in your system. in fact, that is one of the key roles of the preamp - to improve the interface between source units and amplifiers. besides, what if i have a CD player that doesn't even use IC opamps? what if my plug-in module doesn't fit in my cd player? how am i going to route power supply, control leads, etc. to the module? i don't want to drill a bunch of holes in my CD player chassis. even if i got it to work, how am i going to switch between my CD player and my surround sound setup? i'd still need a 6-channel switch then. and what if i have multiple multichannel sources? e.g. DVD-A and SACD both. i could go on and on... but as you can see, a plug-in module just doesn't help me any.
as i mentioned before, this preamp is meant to fill in a niche - a purist but flexible multi-channel preamp. i'm building it because i can't find anything on the market like it, and even if i could it would probably be either a compromise sonically or way out of my price range.
marc
How about this as a design idea:
A PCB that has 1) 1 channel of solid state gain AND an integrated (DC controlled?) volume control/attenuator. Is there such a thing as an "audiophile quality VCA?"
I admit I cannot offer any specific ideas about how to attenuate the input signal, but a DC control strikes me as the lowest noise solution.
If the design was one channel of attenuation plus gain (turn it down, so you can boost back up) on a single PCB, then a builder could make it as many channels has needed. Plus a the bonus of future channels.
How about each card has an integrated regulated power supply? This would allow for a 6 channel setup to be quasi-dual (quasi-sexto?) power supplies.
My 1.5 cents worth:
Aud_Mot
A PCB that has 1) 1 channel of solid state gain AND an integrated (DC controlled?) volume control/attenuator. Is there such a thing as an "audiophile quality VCA?"
I admit I cannot offer any specific ideas about how to attenuate the input signal, but a DC control strikes me as the lowest noise solution.
If the design was one channel of attenuation plus gain (turn it down, so you can boost back up) on a single PCB, then a builder could make it as many channels has needed. Plus a the bonus of future channels.
How about each card has an integrated regulated power supply? This would allow for a 6 channel setup to be quasi-dual (quasi-sexto?) power supplies.
My 1.5 cents worth:
Aud_Mot
No Name Preamp
Any major collaborative project requires the end product to be given a name (at least a tempory one), so that the participants and contributors are able to visualise and identify with the anticipated result.
In honour of this thread starter, I motion that this project be named - 'The Dork '.
http://www.dictionary.com/search?q=dork
Usefull suggestions from the committee are welcomed and encouraged.
Eric, Hon Sec.
Any major collaborative project requires the end product to be given a name (at least a tempory one), so that the participants and contributors are able to visualise and identify with the anticipated result.
In honour of this thread starter, I motion that this project be named - 'The Dork '.
http://www.dictionary.com/search?q=dork
Usefull suggestions from the committee are welcomed and encouraged.
Eric, Hon Sec.
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