That's really smart.
The sender and receiver match.
For a computer as a source, it is typical to use the computer's digital volume control, but it doesn't usually work well at extremes. So, it could be useful to have 0db, 6db, and 15db options at a preamplifier; possibly a bypass, low, high selector switch.
Or, for phone as a source. . .
I'm thinking PT-810 bluetooth device plus THAT1646 may be a cleaner way to get music out of the phone. The output is better than the typical phone's headphone jack. In my experience, the economical little bluetooth device has a huge advantage in that providing it with a clean power supply of its own, is very easily done.
In that way, it routinely beats the output quality of computer upgrade sound cards that don't have the advantage of their own private power supply.
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Mouser ordering works now!
The friendly folks at Mouser have corrected the bug in their system. The ordering of multiple projects works correctly now.
Thanks to those who sent me their invoice numbers. They were helpful in getting the issues sorted out.
~Tom
The friendly folks at Mouser have corrected the bug in their system. The ordering of multiple projects works correctly now.
Thanks to those who sent me their invoice numbers. They were helpful in getting the issues sorted out.
~Tom
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Tom,
As they acknowledge their mistake does that mean they will be sending out our missing components?
Thanks for your suggestions. It would be nice to eventually build in a DAC and some alternate input sources, e.g. bluetooth, and a selector switch for example. However, little steps for me 🙂 I'm trying to figure out a simple volume control based on a recommendation from Tom. Rather, this was his simplest recommendation - he did recommend some others, but I've started a thread in the Analog line level forum asking about this.
Volume control thread
If you have any ideas please let me know.
Hi,
Tom,
- Maybe you can ask them for me to get a credit note... (I sent to you a MP)
- As I had to order again 4 connectors, I had to pay $25 more (shipping fees) due to this bug. 😡!
Tom,
- Maybe you can ask them for me to get a credit note... (I sent to you a MP)
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That's what I wish to avoid. Really I think they should refund your shipping too.
Tom,
They should charge for the parts but with free shipping.
If you could give a copy of the email where they acknowledge this error) to the effected users then this should help them get the money back on shipping. If they are prepared to do the honourable thing.
Hey Tom, interested in building a version of this amp. Is it possible to increase the power supply rails to achieve 50 Wpc with this amp? If so what voltage rails should I be looking for? Thanks!
Tom,
I phoned Mouser UK and spoke to a helpful lady called Lucia to explain the error with combined orders.
I have ordered the missing components and she has arranged to waive the charge on shipping as a gesture of good will.
Post on small orders would normally cost an extra £12.
The bill has just come through confirming free shipping. 🙂
Aive,
FWIW the maximum output volume difference would be virtually imperceptible. A mere 1.2 dB.
It will also literally make no difference at all with driving difficult speakers.
You can use this easy tool:
Crown Audio - Professional Power Amplifiers
"Ultra-low 0.00035 % THD+N (35 W, 8 Ω, 1 kHz)"
With no changes whatsoever, you could get approximately 40W at a momentarily less glamorous THD figure.
Every time you double the amplifier output power, you get just 3db more out of a speaker. The difference in decibels from the speaker, compared with a 40W and a 50W amp is one decibel. It would be very difficult to notice that difference.
So, that means two things:
1). If you thought 50W would do, a rather sturdy 35W~40W will also do (just use a higher current transformer, not a higher voltage transformer).
2). Or if you thought that 35W is insufficient for your needs, then you can be absolutely certain that 50W isn't enough either (because of almost no difference in speaker output decibels). For a significant difference in decibel output of the speaker, you'd be looking for about 140W. The chip-amp available for that is LME49830. With 140W, you'd get 6db more than with 35W. It may be less costly to purchase speakers with 6db more efficiency.
Here's a funny thing. 87db speaker compared to 96db speaker.
86db speaker.
1W, 87db
2W, 90db
4W, 93db
8W, 96db
16W, 99db
32W, 102db
64W, 105db
128W, 108db
256W, 111db
96db speaker
1W, 96db
2W, 99db
4W, 102db
8W, 105db
16W, 108db
32W, 111db
86db speaker.
1W, 87db
2W, 90db
4W, 93db
8W, 96db
16W, 99db
32W, 102db
64W, 105db
128W, 108db
256W, 111db
96db speaker
1W, 96db
2W, 99db
4W, 102db
8W, 105db
16W, 108db
32W, 111db
Am I right?
If we have speakers of 85/86/87 dB/W/m at "8 ohms" but with minimum of 3 or 4 ohms I think we need more current and not more power.
So in my case (86db and minimum of 4 ohms), I think it is preferable to await the development of PCB with LM4780 to build an amplifier with two parallel PCB.
Am I right?
If we have speakers of 85/86/87 dB/W/m at "8 ohms" but with minimum of 3 or 4 ohms I think we need more current and not more power.
So in my case (86db and minimum of 4 ohms), I think it is preferable to await the development of PCB with LM4780 to build an amplifier with two parallel PCB.
Am I right?
Last I checked, Ohm's law said: E = I * R. Also P = E * I. --> P = E^2/R = I^2 * R.
If you apply a voltage of 1 V to an impedance of 1 Ω, it will result in a 1 A current through the impedance. Similarly, if you apply a current of 1 A to an impedance of 1 Ω, 1 V will develop across the impedance.
Above assumes that the source has sufficient compliance (i.e. that the voltage source can actually deliver 1 A and the current source 1 V, respectively).
The Modulus-86 is perfect for driving 4-8 Ω*speakers at ±28 V rails. It will deliver about 65 W into 4 Ω and 38 W into 8 Ω.
If you need more power, you need to increase the supply voltage. The Modulus-86 will deliver about 50 W into 8 Ω on ±35 V rails, but cannot deliver enough current to drive a 4 Ω load to the ±35 V rails. Hence, if you want to operate at ±35 V rails for higher output power, and need to drive a 4 Ω load, I suggest using the Parallel-86.
Speaking of... I have reached the 99 % confidence level on the Parallel-86 circuit itself. This means that I’ve completed the circuit design, run the simulations, built the prototypes, and all those went well. I’m currently laying out the circuit board for the Parallel-86 and expect that to complete over the weekend or by the end of the month for sure. If all goes well, I expect to launch the Parallel-86 by mid-April.
The first batch of boards will be around a dozen boards. Those will be used for my first build. Once I have confirmed that it works well, I will order more boards.
I just started the website for the Parallel-86. It's not live yet, but I'll keep pecking at it. The layout has higher priority, though.
~Tom
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Higher output power due to the ability to operate at higher supply voltages. See my post above (I think our posts crossed).
Running two channels in a bridge is pretty easy. Running two channels in parallel is actually a challenge to do well. If you read DIY Audio for a while, you'll see that many people have tried and they usually get into trouble with the two amp halves not sharing the current evenly. This issue gets even further complicated in a composite amp like the Parallel-86.
~Tom
https://www.google.com/search?q=lm3886+3875+kef+ls+50+q100
-> http://www.diyaudio.com/forums/chip-amps/79303-chip-amp-photo-gallery-283.html#post4168988
KEF LS50
-> http://www.diyaudio.com/forums/chip-amps/79303-chip-amp-photo-gallery-283.html#post4168988
Standard chipamp build. Trafos are 2x160vA each 2x22v audio grade from Toroidy.pl. they are very quiet.
I don't know yet if the copper heatsink will be enough but until now the chips haven't heated up much at normal listening levels.
The sound is very punchy with powerful and tight bass in to a pair of KEF LS50's
KEF LS50
Description: Two-way, reflex-loaded, stand-mounted loudspeaker. Drive-units: Uni-Q driver array with 1" (25mm) vented aluminum-dome tweeter, 5.25" (130mm) magnesium/aluminum alloy-cone woofer. Crossover frequency: 2.2kHz. Frequency range (–6dB): 47Hz–45kHz. Frequency response: 79Hz–28kHz, ±3dB. Sensitivity: 85dB/2.83V/m. Nominal impedance: 8 ohms. Minimum impedance: 3.2 ohms. Harmonic distortion (second and third harmonics, 90dB, 1m): <0.4%, 175Hz–20kHz. Amplifier requirements: 25–100W. Maximum output: 106dB.
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So what do you advise me to my KEF Q100?
Those speakers are not a difficult load and can be driven with ease from all kinds of amplifiers.
Do you own a Sound pressure metre?
If not download a free Sound Pressure Metre application for a smart phone have a listen to your typical listening levels (typical music programme material, not exclusively low bass that the metre will have problems measuring). Work out what sound pressure levels you feel you need.
Measure/estimate how far you sit from the speakers, what maximum volume levels you expect from the speakers and how much headroom you require.
I would say 85 dB is loud in most domestic situations, add 10 dB headroom for peaks (95 dB is extremely loud and would be heavily distorted in the bass from a small speaker anyway; even if used in the near-field).
Look at the Crown page in my earlier post. They have an amplifier power requirement calculator on the same page. You could be surprised by how little power you really need.
If you want more controlled bass use the port bungs for sealed operation.