AMP HEAD Build Thread

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bobsone
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Re: AMP HEAD Build Thread

Postby bobsone » Thu Mar 03, 2016 10:48 pm

Hi
I have a very small MITX case in which I have fitted a phono preamp, FM transmitter and a small toggle on/off circuit so I can still use the push button on the front panel. The case has the usual onboard (low power PC) 3, 5, 12 volt etc rails which are supplied by a 12v 60w brick.

The plan is to also have a headphone preamp in the same case so I have been searching the web for a compatible, (e.g. PCB size, supply voltage) quality preamp.

I see the power requirements of this preamp are +/-12v to +/-24v, would running this off the MITX 12v rail work, be ok?

Also, r.e. the opamps,
Am I correct in concluding that the OPA2604AP is a better quality/cleaner chip than the NE5532AP, and what is the difference between a NE5532P and a NE5532AP.

Thanks

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Joe Malone
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Re: AMP HEAD Build Thread

Postby Joe Malone » Mon Mar 07, 2016 12:22 pm

bobsone wrote:Hi
I have a very small MITX case in which I have fitted a phono preamp, FM transmitter and a small toggle on/off circuit so I can still use the push button on the front panel. The case has the usual onboard (low power PC) 3, 5, 12 volt etc rails which are supplied by a 12v 60w brick.

The plan is to also have a headphone preamp in the same case so I have been searching the web for a compatible, (e.g. PCB size, supply voltage) quality preamp.

I see the power requirements of this preamp are +/-12v to +/-24v, would running this off the MITX 12v rail work, be ok?

You can fit 2 x 6v2 zener diodes to the AMP HEAD and connect the -V & -INs to MITX 0v and the +V to the MITX 12v (Do not connect anything to the 0v on the AMP HEAD PCB) Then Use the 2 +INs for your audio in from phono/FM etc. The whole headphone TRS output will be sitting at +6v which is fine as you are unlikely to plug this back into phono preamp. The 12v power rail will limit the headroom but if you know the headphones impedance you will use you could make the 470R buss resistors lower to value to regain more headroom.

Also, r.e. the opamps,
Am I correct in concluding that the OPA2604AP is a better quality/cleaner chip than the NE5532AP, and what is the difference between a NE5532P and a NE5532AP.

Thanks


NO we only use OPA2604AP for +/-24v rails as it is one of the few opamps that can run on this high voltage. For this I would just use NE5532A opamps. The A is lower noise type.
Joe :-)
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moatl
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Joined: Mon Feb 15, 2016 6:08 pm

Re: AMP HEAD Build Thread

Postby moatl » Wed Mar 09, 2016 3:19 am

Hey Joe,

I just finished my first Headamp and I have a strange little problem:

It actually sounded great from the first moment but then after a couple of minutes the sounds gets really distorted.
I can go away after a little while but it'll come back within minutes.

I double checked all solder joints and even desoldered most of them but it didn't help

The ICs are placed on sockets, but I experienced in the past that sometimes those sockets can be tricky.
I mean I could try to solder the ICs to the pcbs directly?

I also noticed that when no signal runs through the amp the output is silent maybe with a little bit of noise if the pot is fully CW.
But when the above mentioned happens without signal going through - the noise level rises considerably.

Any idea?

I'm building 4 of them and this is the first one - I need to get them going until Thursday so help would be really appreciated! :)

Thanks in advance
Martin

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Re: AMP HEAD Build Thread

Postby Joe Malone » Wed Mar 09, 2016 7:06 am

moatl wrote:Hey Joe,

I just finished my first Headamp and I have a strange little problem:

It actually sounded great from the first moment but then after a couple of minutes the sounds gets really distorted.
I can go away after a little while but it'll come back within minutes.

I double checked all solder joints and even desoldered most of them but it didn't help

The ICs are placed on sockets, but I experienced in the past that sometimes those sockets can be tricky.
I mean I could try to solder the ICs to the pcbs directly?

I also noticed that when no signal runs through the amp the output is silent maybe with a little bit of noise if the pot is fully CW.
But when the above mentioned happens without signal going through - the noise level rises considerably.

Any idea?

I'm building 4 of them and this is the first one - I need to get them going until Thursday so help would be really appreciated! :)

Thanks in advance
Martin


HI Martin It will not be the IC sockets especially if it is one of our kits as we use machined socket. Email me some photos of your wiring and whole build setup and amp head pcb top and bottom and let me know what you are powering them with?
Joe :-)

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yodermr
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Joined: Wed May 12, 2010 3:46 am

Re: AMP HEAD Build Thread

Postby yodermr » Wed May 25, 2016 4:32 am

Hello all
I just got going on assembling / installing 3 amp headphone units. A few questions from my novice brain... if you'd be so kind:

I need to install the provided zener diodes for the power supply I am using (48v). Am I correct in thinking that the end with the black band is the positive end?

I will be using one power supply to power the 3 units that will be installed in three separate boxes. Do I simply daisy chain +V, 0 and -V between each unit and the power supply?

Similarly, I will have one L/R headphone cue signal line that needs to go to each headphone unit. So I simply daisy chain +L, -L, +R, -R between them?

I read somewhere that the ribbon cable might do this, I don't have a ribbon cable. Hopefully I can do the runs with power cable and mic cable, respectfully?

Thanks for your assistance
Mark

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Re: AMP HEAD Build Thread

Postby Joe Malone » Sat May 28, 2016 11:19 am

yodermr wrote:Hello all
I just got going on assembling / installing 3 amp headphone units. A few questions from my novice brain... if you'd be so kind:

I need to install the provided zener diodes for the power supply I am using (48v). Am I correct in thinking that the end with the black band is the positive end?

The stripe end of the zener is the anode. So match the stripe to the thicker stripe end of the overlay. Doesn't matter what colour it is.

I will be using one power supply to power the 3 units that will be installed in three separate boxes. Do I simply daisy chain +V, 0 and -V between each unit and the power supply?

Yes correct.

Similarly, I will have one L/R headphone cue signal line that needs to go to each headphone unit. So I simply daisy chain +L, -L, +R, -R between them?

Yes correct. 0v is audio shield as well so only one 0v is needed in the daisy chain.

I read somewhere that the ribbon cable might do this, I don't have a ribbon cable. Hopefully I can do the runs with power cable and mic cable, respectfully?

Yes the ribbon does all of this for you as it has the audio and power on it. If driven by a modern low output impedance balanced out you will supprised how far you can run the ribbon twisted without hum or noise pickup between amp head modules. Another way is to use Cat6 lan cable and RJ connectors.
Joe :-)

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themaproom
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Joined: Fri Jun 16, 2017 1:43 am

Re: AMP HEAD Build Thread

Postby themaproom » Fri Jun 16, 2017 10:25 am

Hello,

I am hoping to use AMP HEAD units to power a studio headphone system. I want to make 8 personal mixers with 8 mono and 1 stereo channels each with level and pan/balance. I am undecided on whether to set this up as balanced or unbalanced. I will be sending both balanced and unbalanced signals to the mixers depending on whether I am using my console (Speck M72) or the computer (Lynx Aurora) to make headphone mixes.

The upside to unbalanced is less wiring that I need to do throughout my studio, though if balanced really seems better then I'm happy to do the extra work.

I am also wondering about what sort of summing would work best on the front end of the AMP HEAD. Passive or ACN? Is there by any chance a schematic of the recommended summing drawn up already that I could go by?

To summarize: Balanced or unbalanced? Passive or ACN (and is there a recommended summing schematic that I could check out)?

Thanks for the help!
Josh Powell
www.themaproomstudio.com

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Joe Malone
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Re: AMP HEAD Build Thread

Postby Joe Malone » Fri Jun 16, 2017 12:08 pm

themaproom wrote:Hello,

I am hoping to use AMP HEAD units to power a studio headphone system. I want to make 8 personal mixers with 8 mono and 1 stereo channels each with level and pan/balance. I am undecided on whether to set this up as balanced or unbalanced. I will be sending both balanced and unbalanced signals to the mixers depending on whether I am using my console (Speck M72) or the computer (Lynx Aurora) to make headphone mixes.

The upside to unbalanced is less wiring that I need to do throughout my studio, though if balanced really seems better then I'm happy to do the extra work.

I am also wondering about what sort of summing would work best on the front end of the AMP HEAD. Passive or ACN? Is there by any chance a schematic of the recommended summing drawn up already that I could go by?

To summarize: Balanced or unbalanced? Passive or ACN (and is there a recommended summing schematic that I could check out)?

Thanks for the help!
Josh Powell
http://www.themaproomstudio.com


HI Josh do a rough sketch of the controls you are wanting and inputs. I have a new stereo variable H pad pcb coming that Rob Squire designed and requested which sounds perfect for this. Balanced is usually the best as that works the AMP Head perfectly and less noise pickup around the studio. Yes I can email schematic but if you do a rough sketch I will be able to show you exactly what to do.
Joe :-)

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themaproom
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Re: AMP HEAD Build Thread

Postby themaproom » Fri Jun 16, 2017 1:49 pm

Joe Malone wrote:
HI Josh do a rough sketch of the controls you are wanting and inputs. I have a new stereo variable H pad pcb coming that Rob Squire designed and requested which sounds perfect for this. Balanced is usually the best as that works the AMP Head perfectly and less noise pickup around the studio. Yes I can email schematic but if you do a rough sketch I will be able to show you exactly what to do.


Great, thank you! Here's a rough sketch of the controls I want.
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Re: AMP HEAD Build Thread

Postby Joe Malone » Tue Jun 20, 2017 1:38 pm

themaproom wrote:
Joe Malone wrote:
HI Josh do a rough sketch of the controls you are wanting and inputs. I have a new stereo variable H pad pcb coming that Rob Squire designed and requested which sounds perfect for this. Balanced is usually the best as that works the AMP Head perfectly and less noise pickup around the studio. Yes I can email schematic but if you do a rough sketch I will be able to show you exactly what to do.


Great, thank you! Here's a rough sketch of the controls I want.


Ok the New variable stereo H Pad PCB coming in about 2 weeks will let you build that easily.

What input connectors are you going to use XLR , TRS , DB25?
Joe :-)

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themaproom
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Re: AMP HEAD Build Thread

Postby themaproom » Wed Jun 21, 2017 2:13 am

Joe Malone wrote:
Ok the New variable stereo H Pad PCB coming in about 2 weeks will let you build that easily.

What input connectors are you going to use XLR , TRS , DB25?


Ok great! Since I have ten channels I am thinking that I'll use 12 channel snake cable and DB37 connectors.

wackid
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Re: AMP HEAD Build Thread

Postby wackid » Mon Feb 19, 2018 6:27 pm

I am looking for an headphone amp with balanced in and balanced out.
Came across this neat little amp.

On my DAC there are two 3 pins XLR out. How do i connect these on the board? I only see -L +L and -R and +R and 0V. Do i connect both XLR output ground on 0V?
I guess i need two PCB's to get balanced out? And if so can i use i need two TRS 6.3mm plugs to get balanced out?

Sorry for the noob questions....just want to be sure before purchasing the boards.

And whats the difference to the Headamp 2 and Headamp? is see double Bus outputs and some rgb possibilities?

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Re: AMP HEAD Build Thread

Postby Joe Malone » Tue Feb 20, 2018 10:01 am

wackid wrote:I am looking for an headphone amp with balanced in and balanced out.
Came across this neat little amp.

On my DAC there are two 3 pins XLR out. How do i connect these on the board? I only see -L +L and -R and +R and 0V. Do i connect both XLR output ground on 0V?

Yes correct. pin 1 on both go to 0v.

I guess i need two PCB's to get balanced out?

Yes

And if so can i use i need two TRS 6.3mm plugs to get balanced out?

To make each pcb balanced out wire L+ to R- and L- to R+ and feed left to one pcb and right to the other pcb. This will give you balanced out on each TRS with tip being + and ring being -. The 2 pcbs can be made to run with one stereo 10k log pot for volume if needed.

And whats the difference to the Headamp 2 and Headamp? is see double Bus outputs and some rgb possibilities?

AMP head II can take larger stereo pots and has 3 wire headers for remote mounting TRS or other headphone sockets.
Joe :-)

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