• These commercial threads are for private transactions. diyAudio.com provides these forums for the convenience of our members, but makes no warranty nor assumes any responsibility. We do not vet any members, use of this facility is at your own risk. Customers can post any issues in those threads as long as it is done in a civil manner. All diyAudio rules about conduct apply and will be enforced.

Some more really small amps

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Jump to Latest
IO390

IO390

Member
Joined 2014
New version now available.

Specifications:

-Size: 1.5”x1” (38x25mm)
-Input voltage range: 4.5-24V
-Efficiency: 90%
-Power: Limited to 2x21W(8Ω) 2x52W(4Ω) @ THD:10% (22V).
-Minimum THD: 0.05% at 0-2W
-Standby current: 50mA
-Sensitivity: 1Vp-p (@20dB)
-Gain: 20dB/32dB (selectable)
-Input impedance: 60KΩ (20dB), 15KΩ (32dB)
-Minimum load impedance: 1.6Ω

Features:

-DC offset detection at output to prevent speaker damage
-No ‘phone buzz’
-Includes comprehensive instruction manual.
-Hand assembled and tested in the UK
-No turn on pop
-Full L-C output filter with EMI snubbers
-Optional differential inputs (selectable on the board)
-Microcontroller on board for error reporting and precise turn on delay
-Status LED. Solid light when amp is “on”, flashes when amp reports a fault

Full specs and info on my store page: http://www.io390.co.uk/product/25w-amplifier-v2

Price is £24.99 plus postage and includes a full set of connectors.

y7M163El.jpg


lO91uLKl.jpg


OePGyWUl.jpg


Thanks for looking!
 
Last edited:
von Ah

von Ah

Member
Joined 2008
Paid Member
A moderator will move it when they get a chance, I'm sure. I don't think you need to delete the thread. If you haven't already, you can click the red triangle 'report' icon under your username on the left side to call their attention to your last post.
 
IO390

IO390

Member
Joined 2014
xrk971 said:
Very nice work! Those sure are cute and would be great in almost any portable app. This would be one heck of a headphone amp (5v supply) for someone wanting to make their own cans using 2in fullrange drivers! :) Vifa TC6FD hmm....

What does shipping to US cost?
Click to expand...

Thanks for the kind words :)

Shipping to the US is £3.50 ($5 roughly) for 5-7 day. Anything quicker is a lot more expensive. Info on shipping is on my shop page.
 
IO390

IO390

Member
Joined 2014
xrk971 said:
Thanks for the info on shipping -$5 is very reasonable. I noticed that the pin out on the speakers shows + - - +. Is that correct ? On the 3116 it is + - + - and Sure actually mislabeled their boards. The 3132 may be different though.
Click to expand...

Definitely correct: http://www.ti.com/lit/ds/symlink/tpa3132d2.pdf

This is the fifth board I've made with the TPA3132 (only second that I've sold online), so I should hope I haven't been getting it wrong this whole time :)
 
Saturnus

Saturnus

Member
Joined 2005
xrk971 said:
Thanks for the info on shipping -$5 is very reasonable. I noticed that the pin out on the speakers shows + - - +. Is that correct ? On the 3116 it is + - + - and Sure actually mislabeled their boards. The 3132 may be different though.
Click to expand...

Since the inputs are differential you don't have to run the signal input to the positive input on the chip. If board layout is better with signal input feed to the negative input instead then you just relabel the outputs instead.
 
Last edited:
H

Hemisphere

Member
Joined 2009
Really good work! I've ordered 2 (sent you a message about possibly specifying the wrong gain level in the order form)

I like the idea of the 1x1" version even if it seems like no one would have a use for something so small, you never know.

At that size, you could call it the stAMP.

There was a lot of todo over on the Speakerplans forum about 'The Vamp' (http://www.thevamp.co.uk) mostly over the rubbish component selection versus high cost/marketing driven approach. A one inch square amp would be perfect for a gadget like that where there are few other limitations on the size of the enclosure.
 
Last edited:
IO390

IO390

Member
Joined 2014
Hemisphere said:
Really good work! I've ordered 2 (sent you a message about possibly specifying the wrong gain level in the order form)

I like the idea of the 1x1" version even if it seems like no one would have a use for something so small, you never know.

At that size, you could call it the stAMP.

There was a lot of todo over on the Speakerplans forum about 'The Vamp' (The VAMP® | Transform any speaker into a portable Bluetooth® speaker) mostly over the rubbish component selection versus high cost/marketing driven approach. A one inch square amp would be perfect for a gadget like that where there are few other limitations on the size of the enclosure.
Click to expand...

Replied to your email.

I like your name idea, it's not far off already:

xSyxO5M.jpg


I could have a go at a 1" square design, can't promise anything on that though.

Looking at the Vamp thingy, how big actually is it? Also what's the output power etc, the website seems to be 100% fancy graphics as opposed to anything useful.
 
H

Hemisphere

Member
Joined 2009
I think it's around 60-65mm cubed with a slice cut off. Output power was listed as '4 watts peak' in their Kickstarter campaign (which raised a lot of funds, followed by a 5 month delay for delivery and quite a lot of bad reviews) but they quickly dropped that (and all other meaningful specs) from later promotional material/manuals.
 
Last edited:
IO390

IO390

Member
Joined 2014
Only so much one can do with a USB power supply I suppose. I've never designed anything which draws more than 500mA from a single USB socket, and at 4W that's nearly an amp current draw...

I read that there is "less bass" with the bluetooth. I find this surprising, as the BT signal is digital. Packet loss perhaps? Also the interface circuitry between the bluetooth module they're using to the amp will have a say in what happens.
 
Saturnus

Saturnus

Member
Joined 2005
IO390 said:
Only so much one can do with a USB power supply I suppose. I've never designed anything which draws more than 500mA from a single USB socket, and at 4W that's nearly an amp current draw...

I read that there is "less bass" with the bluetooth. I find this surprising, as the BT signal is digital. Packet loss perhaps? Also the interface circuitry between the bluetooth module they're using to the amp will have a say in what happens.
Click to expand...

"4W peak" is 400mA current draw. And that's probably into an unrealistic 2 ohm load and with 10% THD or worse.

The bluetooth module they're using could have incorrectly dimensioned output capacitors if they picked up a standard cheap module meant for headsets which seems likely. That would account for the missing bass over bluetooth.
 
H

Hemisphere

Member
Joined 2009
IO390 said:
Only so much one can do with a USB power supply I suppose. I've never designed anything which draws more than 500mA from a single USB socket, and at 4W that's nearly an amp current draw...

I read that there is "less bass" with the bluetooth. I find this surprising, as the BT signal is digital. Packet loss perhaps? Also the interface circuitry between the bluetooth module they're using to the amp will have a say in what happens.
Click to expand...
Funnily enough the topic of USB as an appropriate power supply just came up on another thread, so I'll paste what I wrote on there:

*most* portable speakers that charge via USB will have a small amp in the region of 3 Watts.

You've generally got to look to the £70+ price bracket but if you search (and research) you will find many [speakers with a 10-20 Watt output and USB charging] After a while you get a feel (based on a balance of price, claimed specs, manufacturer reputation and customer reviews) whether the Wattage ratings are legitimate or not. Many aren't. Some are.

12 hours of charge at 500ma 5v will give you 30 Watt/hours of juice, if you're using a 90% efficient amp (call it 75% to factor in quiescent current and lower efficiency at lower output levels) that gives you 22.5 Watts to play with. Average music program is about 1/8th of RMS signal so we can multiply that by at least 8 (more if you're high passing around 100Hz as many small speakers do), giving a total of 180 Watts equivalent, or approximately 12 hours of continuous 15 Watt program output per 12 hours of charging.

In the real world due to the significant bass cut below 100Hz, (where most of the musical energy is in modern music) you could expect to get that 12 hour output from a 6 hour charge or even less.

Some of my estimates may be significantly off but I guarantee it's in that ballpark. USB is a perfectly viable medium for charging speakers.
Click to expand...

As I say my numbers are probably way out but basically if the device has a battery (greater than 5v) inside that works as the buffer for the USB charger, and in normal use (most don't play their devices at maximum volume all the time) the balance of charging versus mobile use tends to be acceptable (at least 1:1 usually 2:1 or greater ratio of play time versus charging time)
 
Last edited:
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Top Bottom