diyAudio - Uncategorized
Go Back   Home > Forums > Blogs > BuildMeSomething

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Uncategorized Entries with no category
Old

A Low Power Desktop Amp [LPDA]

Posted 1st June 2013 at 11:24 AM by BuildMeSomething

Well, this little project is finished and working. Quite pleased that measured offset dropped to <1 mV on both channels once the amp was in the chassis and wired.

Listening impressions: This is where I state that it's the best amp I've listened to, and it is... Unfortunately, it just highlights any shortfalls with the speakers. The Mission 773e have never performed better or sounded clearer. However, you are just as aware on how quickly these speakers lose the plot with more complex music... In the long run I hope to match the sound of the Sennheiser HD-650 driven by "The Wire" se-se HPA, the FH3 are my first try at achieving this...

Paul
Attached Thumbnails
Click image for larger version

Name:	LPDA1.JPG
Views:	249
Size:	419.5 KB
ID:	1087   Click image for larger version

Name:	LPDA2.JPG
Views:	150
Size:	371.0 KB
ID:	1088   Click image for larger version

Name:	LPDA3.JPG
Views:	155
Size:	387.2 KB
ID:	1089  
diyAudio Member
Posted in Uncategorized
Views 451 Comments 0 BuildMeSomething is offline
Old

Nearly There - A Low Power Desktop Amp

Posted 17th May 2013 at 07:09 PM by BuildMeSomething

Well, this project is nearing completion. The very last pieces needed have been ordered and will be delivery early next week. The chassis and custom PCB enclosure/heat spreader were collected on Thursday morning from FedEx and UPS. Thursday night was spent drilling and tapping holes for the various parts. Now its some wire placement and waiting on the last pieces...

Problems: None really, a few sizing issues for connecting wires and the caps to the boards. Though, all are just big enough with a little patience. Certainly no issues that require a halt to the project or new PCB's.

Speakers: Decision made, Frugel-Horn Mk 3 with Mark Audio Alpair7.3 drivers... Why? I love the strong imagining and detail given by the little 3" FC full range speakers, so thought I'd give some proper full rangers a go. Should be fun trying to build these
Attached Thumbnails
Click image for larger version

Name:	BMS_LPDA_3.JPG
Views:	152
Size:	511.1 KB
ID:	1071   Click image for larger version

Name:	BMS_LPDA_4.JPG
Views:	126
Size:	448.4 KB
ID:	1072   Click image for larger version

Name:	BMS_LPDA_5.JPG
Views:	375
Size:	492.6 KB
ID:	1073   Click image for larger version

Name:	BMS_LPDA_6.JPG
Views:	128
Size:	509.3 KB
ID:	1074   Click image for larger version

Name:	BMS_LPDA_7.JPG
Views:	147
Size:	436.4 KB
ID:	1075  

diyAudio Member
Posted in Uncategorized
Views 332 Comments 0 BuildMeSomething is offline
Old

Power Up! - A Low Power Desktop Amp

Posted 28th April 2013 at 03:04 PM by BuildMeSomething
Updated 8th May 2013 at 06:38 PM by BuildMeSomething

The Amp boards arrived Saturday, unfortunately, I was just leaving for work so they'd have to wait. Everything looked OK on them.

Initial power up test was done with both LME49990 in place but only one LME49600 mounted on each channel [PSU used was a modified "The Wire" unit meant for testing the A/B Power Amp at +/-25Vdc, now set at +/-15Vdc. It was getting quite hot as it was dropping 10V per rail]. That went Ok, so the rest of the 49600 were put in place and powered up once more... Again, everything OK.

Measured offset:

Left channel: 27mV
Right channet: 8mV

Foam board speakers are progressing, and will be ordering a heatsink this week also.

Update [13-04-30]: Been a little bit worried about the higher offset value on the left channel, though it's not at a bad level overall. Once the amp has been on awhile, it appears to settle at 25.9 mV.

Made a quick SE input>volume pot AC coupled...
Attached Thumbnails
Click image for larger version

Name:	BMS_LPDA_1.JPG
Views:	422
Size:	483.0 KB
ID:	968   Click image for larger version

Name:	BMS_LPDA_2.JPG
Views:	232
Size:	476.0 KB
ID:	969   Click image for larger version

Name:	mFonken_2.JPG
Views:	256
Size:	453.8 KB
ID:	984   Click image for larger version

Name:	mFonken_4.JPG
Views:	179
Size:	419.4 KB
ID:	985  
diyAudio Member
Posted in Uncategorized
Views 766 Comments 6 BuildMeSomething is offline
Old

Progressing - Low Power Desktop Amp

Posted 19th April 2013 at 09:49 AM by BuildMeSomething
Updated 25th April 2013 at 08:36 AM by BuildMeSomething

Holiday: Bad weather to a point it was near impossible to take a steady photograph due to the gusting winds. Hiding from the winds meant poor vantage points, very much non-idealistic for photographing landscapes.

Digi-key: The order turned up on the Monday morning, roughly 10 minutes before leaving. The PSU boards must have arrived mid week, a neighbour had those...

The parts order was enough components for one power supply and one amp. The PSU is assembled but untested as yet. The toroidal and 10K Alps RK27 are to be ordered from RS Components later today.

PCB issues: C1-C6... this is where trusting the people who generate default libraries for FreePCB falls down and my inexperience shows. Lead diameter on the caps is 28MIL, default part through-hole diameter is 28MIL... Each lead needed a quick file to reduce its width enough to fit the board. No other issues to report.

I don't think I could have made the overall size of the board...
Attached Thumbnails
Click image for larger version

Name:	BMS_PSU_1.JPG
Views:	149
Size:	327.1 KB
ID:	960   Click image for larger version

Name:	BMS_PSU_2.JPG
Views:	152
Size:	316.9 KB
ID:	961   Click image for larger version

Name:	BMS_PSU_3.JPG
Views:	145
Size:	323.9 KB
ID:	962  
diyAudio Member
Posted in Uncategorized
Views 320 Comments 0 BuildMeSomething is offline
Old

Progression - A Low Power Desktop Amp

Posted 9th April 2013 at 09:06 PM by BuildMeSomething
Updated 13th April 2013 at 09:21 AM by BuildMeSomething

Power supply boards are on their way, as is a full Digikey order for this project. However, no LME49722, which are currently out of stock. Due to that and wanting to keep to a 1 x psu & 1 x amp layout, the amp board underwent a quick re-design. It's now duel mono layout, utilising two LME49990.

Ordered LT1033/LT1085 for the PSU, these should give 3A each [typical]. Plus, six 4,700uf caps to help out. The plan is to run the rails at +/-15Vdc, with a 120VA 2x15V toroidal transformer.

Will place an order for the prototype amp boards on Saturday, just before I go on holiday.

Update (13-04-11): The PSU PCB's still haven't arrived, Plus UPS failed to deliver my Digikey order, this is now in limbo as they're saying "A correct street name is needed for delivery" ... I've talked to both Digi-key & UPS (U.S.) and they have the correct full address, UPS (UK) I can't get hold of... my translation is "Delivery driver can't read a map!"...
Attached Thumbnails
Click image for larger version

Name:	LPDA_layout_1.jpg
Views:	215
Size:	132.1 KB
ID:	956   Click image for larger version

Name:	LPDA_layout_2.jpg
Views:	143
Size:	116.1 KB
ID:	957  
diyAudio Member
Posted in Uncategorized
Views 439 Comments 0 BuildMeSomething is offline
Old

What? - A Low Power Desktop Amp

Posted 6th April 2013 at 08:52 PM by BuildMeSomething
Updated 9th April 2013 at 07:31 PM by BuildMeSomething (Updates)

2] Basically, this is me trying to do a 2-layer PCB layout based on the LPUHP circuit schematic.

I'm using FeePCB for laying out. Not hit any problems with the software yet and it produces Gerber RS247X files. The parts library is none specific, so I'm having to generate footprints from datasheets as I go.

Notes:
1) Untested PCB design [should work though].
2) 2-Layer PCB.
3) 2 channels per board [16 x LME49600].
4) LME49722 with 4x gain.
5) Up to +/-18VDC rails.
6) Separate regulated power supply.
7) Utilise a 10K Alps RK27 for volume control.
8) 8 Watt into 8 Ohm [based on 2VRMS input].

Aim is to create 1 x power supply & 1 x amp board of a small enough form factor to fit in a desktop friendly case. With an output of 8 Watt into 8 Ohm load, for up close & nearfield listening in a small room.

Why the LME49722. Its drop in replacement to the nice 49720 but will run on +/-18VDC,...
Attached Thumbnails
Click image for larger version

Name:	Amp_layout_1.jpg
Views:	134
Size:	133.4 KB
ID:	932   Click image for larger version

Name:	Amp_layout_2.jpg
Views:	124
Size:	116.9 KB
ID:	933   Click image for larger version

Name:	PSU_layout_1.jpg
Views:	281
Size:	144.9 KB
ID:	934   Click image for larger version

Name:	PSU_layout_2.jpg
Views:	146
Size:	136.1 KB
ID:	935  
diyAudio Member
Posted in Uncategorized
Views 410 Comments 0 BuildMeSomething is offline
Old

Why? - A Low Power Desktop Amp [LPDA]

Posted 6th April 2013 at 08:34 PM by BuildMeSomething
Updated 26th April 2013 at 10:26 AM by BuildMeSomething

1] I hold opc's "The Wire" series of headphone and power amps in high regard. Small form factor, simple no nonsense designs and killer performance. God bless that man

I'm fortunate enough to have a few pieces at home. Primary, is the SE-SE headphone amp that gets used for both music and late night movies... Also, under construction is the A/B Power Amp, utilising two 55V/45V DPS-600 smps. This should provide over 100 Watt per channel into 8 Ohm load. Nice, but way to powerful for my spare little room.

opc designed a Low Power Ultra High Performance [LPUHP] Amp giving 16 Watt into 8 Ohm @ 1% THD. This was based upon the headphone amps he'd designed, using the same LME49990 opamp, but paralleled 8 LME49600 buffers.

Unfortunately I didn't have the funds to get both the A/B Power Amp and LPUHP Amp. Plumping for the former...



My little spare room is just that... Its 3m[w] x 2.9m[L] x 2.4m[H] and is full of...
diyAudio Member
Posted in Uncategorized
Views 309 Comments 0 BuildMeSomething is offline
Hide this!Advertise here!

New To Site? Need Help?

All times are GMT. The time now is 07:06 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2