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Looking for custom rack mount amp...need help

post #1 of 8
8/29/10 at 11:01pm
Thread Starter 

 

I've recently gotten into rack mount equipment (19"), and decided to build a rack that will be my computer and audio system. I'm thinking about getting a DAC1 and will need a rack mountable amp to go with it (better than the amp built into the DAC1). Unfortunately, it seems that most rack mount headphone amps on the market are designed more for simple monitoring than audiophile listening. On top of that, I'd like to get the HD650 balanced, which pretty much narrows my choices down to a custom built amp. Any feedback on possible pricing and who/where to go to would be greatly appreciated :)
 
Here are the main features I'm looking for. If I'm listing something dumb, please tell me: 
 
*Solid State
 
*Half rack sized (to be mounted next to a DAC1 using a half rack coupler like the one sold directly from Benchmarkmedia.com)
 
*Balanced (not sure of the types of output connectors or which is best for an HD650)
 
*Will connect to a DAC1, so I guess it would need those twin, three pin balanced (XLR?) inputs
 
*Some basic RCA inputs would be nice too
 
*A single ended 1/4" phono output (possibly for the RCA inputs?)
 
*Simple black faceplate to compliment a black DAC1
 
*If a separate power supply would be necessary/appropriate, would a 1RU, full rack width PS be feasable?
 
 
 
 
I was thinking between $1000-$2000, but I'm really not sure what to expect with pricing of DIY amps. Any suggestion? 
 
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post #2 of 8
8/29/10 at 11:20pm
You can have any of the DIY amps built into a standard rack. It'd be a fairly simple matter as there are lots of rack cases out there. However, you might want to look at the PreSonus Central Station. They run about $500 and have a very nice amp, actually two of them. It has a nice DAC built in, too. They only come in silver, but you might be happy with one, especially at that price. I had one while I was doing the computer-as-source thing and thought highly of it.
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post #3 of 8
8/30/10 at 8:46am

A half rack case would be nice, but you would be limiting yourself to the type of diy amp that could be cased in one.  The half rack version of this case looks like it would the choice for you:

http://www.hammondmfg.com/dwg25.htm

specifically the RMCV9018BK1 (if its 1U you want).  In that case, you'd probably be limited to doing something like a Balanced Mini3 (dual mini3 boards), and you'd have room for the power supply in it now. A pair of dynalo boards might fit side by side, but it would be very close, and it would be important to get the inside measurements for the case before you ordered anything (it's not obvious to me from the Hammond drawings what the internal dimensions are).  You would have to go with an external power supply. 

Both of the above ideas could be done for under $300.. 

 

If you want to spend 1-2K, then go with the Beta 22, but it will have to be a full width case and unless you get funky with chassis mounted output devices, you'd need to go to 2U also. It is one of the top of the heap DIY amps (along with the Dynahi), at least in the solid state range(tube amps usually aren't so "rack friendly", unless you have lots of venting, and start doing stuff like putting the tubes on their sides..) .  If you go with a 2U full width case for the Beta 22, then you could have the power supply internal to it.


Edited by MrSlim - 8/30/10 at 8:48am
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post #4 of 8
8/30/10 at 1:17pm
Thread Starter 
Quote:
Originally Posted by MrSlim View Post

A half rack case would be nice, but you would be limiting yourself to the type of diy amp that could be cased in one.  The half rack version of this case looks like it would the choice for you:

http://www.hammondmfg.com/dwg25.htm

specifically the RMCV9018BK1 (if its 1U you want).  In that case, you'd probably be limited to doing something like a Balanced Mini3 (dual mini3 boards), and you'd have room for the power supply in it now. A pair of dynalo boards might fit side by side, but it would be very close, and it would be important to get the inside measurements for the case before you ordered anything (it's not obvious to me from the Hammond drawings what the internal dimensions are).  You would have to go with an external power supply. 

Both of the above ideas could be done for under $300.. 

 

If you want to spend 1-2K, then go with the Beta 22, but it will have to be a full width case and unless you get funky with chassis mounted output devices, you'd need to go to 2U also. It is one of the top of the heap DIY amps (along with the Dynahi), at least in the solid state range(tube amps usually aren't so "rack friendly", unless you have lots of venting, and start doing stuff like putting the tubes on their sides..) .  If you go with a 2U full width case for the Beta 22, then you could have the power supply internal to it.

Thanks for the insight :) 

 

I was figuring that a half rack would be limiting, but I wanted that size more just to fill in the space next to the DAC1. If a full width 2U case would be "minimal" for a high quality balanced amp with the PSU included, then I can go with that. I'll just need to get a black placeholder piece to put next to the DAC1 (as much as I hate empty unused space).

 

I'll read up on the Beta22 and Dynahi too see which would be more suitable. I was thinking the same about tube amps in a rack, since those seem to favor open ventilation (and I love my Antique Soundlabs OTL MKIII, but those tubes get hot as a light bulb). 

 

I think I'll also just forget about the single-ended option, since the only headphones I'd be using that for are not the highest in quality, and so the DAC1's outputs should be adequate. 

 

Oh, and how much power would be good for an HD650? I might also get other balanced dynamic headphones in the future that may be even harder to drive, so I'm not against having a little more than I need.
 

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post #5 of 8
8/30/10 at 2:02pm
Be careful with the cooling - the Dynahi puts out a fair bit of heat and must be heatsinked well. Even if you can cool it well, be careful it doesn't cook the other components around it.

A couple others you might want to consider are the M^3 and CK2III. Both can be built balanced and the CK2III might be small enough to fit into a smaller case, since it has the power supply on board.
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post #6 of 8
8/31/10 at 7:43pm

 

Oh, and how much power would be good for an HD650? I might also get other balanced dynamic headphones in the future that may be even harder to drive, so I'm not against having a little more than I need.
 


Well, the Beta 22 and the Dynahi are about as powerful as you are going to find, especially in a balanced config, I don't think you'll have to worry there. I don't think the HD650's are THAT hard to drive, even the M3 and CK2III do a fine job with them. As Uncle Eric says, you might want to consider a balanced M3 or CK2III as well, and even though a balanced pair of CK2III boards wouldn't fit in a 1/2 rack case, they would definitely fit in a full rack 1U, including power supplies(and way cooler (temp wise) than either of the "Big Boys".

You'd also have some room to do something cool WRT attenuators, ala the twisted pear Joshua tree, or some of the other micro controlled devices.  Unless you decide you have to own a pair of K1000's (good luck with that), you are unlikely to run into to many headphones that even the M3 or CK2III won't drive.  Even orthodynamics which are notoriously power hungry can be driven quite well by a Hybrid CTH (BR777 bought one of mine and he's very happy with the results driving his "Thunderpants"). 

 

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post #7 of 8
9/1/10 at 2:43pm
Thread Starter 

OK then, that's nice to know :) It seems I have more reading to do to get enough knowhow to even commission someone to make an amp for me. When it comes to the internal circuitry, I have little to no knowledge of how amps work, or which circuits do what. I basically want this balanced amp to be part of my "magnum opus" sound system, within a reasonable budget (no $10,000 amps for me...yet). I wouldn't mind trying to build my own if it has a reasonably practical learning curve, but everything I've read makes it seem like one needs an electrical engineering degree to grasp it. 

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post #8 of 8
9/1/10 at 4:25pm
Oh, no. You do not need an EE to build an amp. Hell, I'm an English major who went on to get other degrees in law and accounting. No formal training other than high school electronics and an amateur radio license. I've picked up a lot from books and fiddling with old tube radios, too.

The best starting point is the CMoy. Parts are about $20 and you'll need a soldering iron and a DMM. You can get both for another $20 or so. From there, you'll know enough to build more complicated PCB-based amps. They're not that difficult, either. Most of it is making sure you solder the right parts in the right places and in the right direction. It might take a little longer to figure out, but it's within the skill set of anyone willing to try. If you pick one of the more popular projects, you'll find lots of support and troubleshooting help in the DIY Forum. One you might want to shoot for is a four channel Beta22 build. It should fit nicely into your budget and then you'd have one of the "final word" amplifiers. Give it some thought, since you'll save a bunch of money and you might really enjoy putting one together. It's sort of like a 3D jigsaw puzzle that is very useful when you finish.
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