Wednesday, 18 April 2018

Can You Jump Start a Car with a Motor Bike?

Can You Jump Start a Car with a Motor Bike? 


This is a common question on the web, with lots of dissipated information between you tube, forums and product reviews. So I have tried to summarise here.

In short this will work if you have a large bike and a small car. You will not be able to jump start a pick up truck with a scooter.

Its all about amps (CCA). A motor bike battery of any size will likely provide a maximum of 300 amps, but more often will be 200 amps.

A car will need 200 amps as a minimum, so the larger your bike, hopefully the larger its battery, and the better luck you will have.

Damage to Either System

The main thing to watch here is voltage. Both system should be 12v otherwise you will damage teh lower voltage one. Bear in mind that most 12V system runs at 14 - 15V (which is confusing).

The only problem I can foresee is that if after you jump start the car, the jump leads are left attached for too long, causing the car's alternator to charge the bikes battery too quickly.

Case Study 1 - Jump Start a Large Pick Up with a 250cc Bike

PROBABLY NOT - This doesn't doesn't work. A large diesel engine will require 500 - 600 amps plus current to start, and a small motor cycle battery will not provide enough current.

Case Study 2 - Jump Start a Small Petrol Car (1.5l) with a Power Bike (900cc)

PROBABLY YES - This would likely work OK, as the two systems are more closely matched in terms of their current requirements at start up. 

A Note on Battery Chemistry

The above applies for all types of Lead Acid battery which are the norm in most bikes and cars. However some upgrade batteries for Motor Bikes use lithium technology. The graph below shows that  lithium batteries but out more amps for their size than lead acid equivalent. 


The (red) line above shows lithium performance, vs lead acid performance (blue). So we can see that whilst a small lead acid battery will not get above 300 amps, a lithium battery can supply up to 1000 amps. Which would be plenty for even a moderate diesel engine start up.

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Wednesday, 7 March 2018

8GB or 16GB of RAM for Heavy Multi Tasking

8GB or 16GB of RAM for Heavy Multi Tasking - Intro


RAM is fairly cheap and easy to install. But how much do you need for heavy multitasking?

8GB or 16GB of RAM for Heavy Multi Tasking - Observations


Prior to my upgrade I was running 4GB of RAM, but owing to 32 bit limitations of 3GB and two 500MB graphics cards, I can only see 2GB of available RAM in performance manager.

This 2GB of RAM was always maxed out, hovering around the 1.8GB mark most of the time during day to day use. I use a 4 monitor set up so can have a awful lot of stuff open.

I recently upgraded to a 64 bit system, and so now I can use more RAM. I have installed 16GB, but how much of this will get used.

Typically I have open:


  • 4 Browser Windows (3 or 4 Tabs Each)
  • 3 MS Word Windows
  • MS Outlook
  • >10 Large PDF Files
  • MS Publisher with lots of Photos
  • Modelling Software or,
  • Sketch Up or,
  • AutoCAD
So how much memory does all this stuff take up? Just 3.67GB:




Windows is actually using a lot more memory standby memory, if we look in resource monitor we can see only 1.4GB Free with around 11GB used in standby. Standby memory hold on to applications that have been closed, in case they are needed again, this will gradually "fill up" the longer you have your machine switched on and you open and close programs.



8GB or 16GB of RAM for Heavy Multi Tasking - Conclusion


8GB will almost certainly be plenty for heavy multitasking. Any more than 8GB and really you are looking at server amounts of memory that give no real benefit. 

Would I have bought 16GB of RAM knowing what I know now? Probably not. But its would still be tempting because the more available memory for standby the better. . . . and there in lies the rub.

As a note aside the best performance upgrade you can ever make (in my opinion) is a solid state drive SSD. Even a old, low spec computer will work twice as fast with an SSD.  

Monday, 26 February 2018

Getting the Best Price at a Builders Merchants

Getting the Best Price at a Builders Merchants  - Intro


For some a trip to a builders merchants may be a daunting prospect. There are a few things to consider before you go as they are not like other shops.

If you have ever been in a builders merchants like Jewson, Travis Perkins or Buildbase, you will notice that the prices (if they are labelled at all) are normally high. Unless you are looking at a special offer price, then you are likley looking at the list price.

Quick Guide 

Getting the Best Price at a Builders Merchants - Ring for a Price


Most products have a List Price. The list price is a made up price that a builders merchants will put on a product hoping that somebody will pay it. The price you "can" pay for the product is often a lot lower.

So the key is to ring up and ask for a "quote" (price) on what you want before you go to the actual "shop". When you have a price, try to negotiate a lower one.

Getting the Best Price at a Builders Merchants - "Better Price Please"


Prices are not fixed, you can try and get a better price. Some staff will do this straight away because they are nice people, others are too lazy or do not care if you pay more.

The conversation might go like this:

You: "Hello could I have a price for 100 concrete blocks please"

Builders Merchant: "We can do those for 75 pence each"

You: "Is that your best price please?"

Builders Merchant "The best we can do is 69 pence a block"

You: "I will be getting some prices elsewhere so is this really your best price?"

Builders Merchants: "Yes" or "we could do them for 68 pence a block"

It is important to do this for everything you intend to buy. If you are building a wall for example, get prices for sand . . . cement. . . even a trowel and bucket before you go to the shop. EVEN get a price for a role of string. . . otherwise you might pay £6 for it.

Getting the Best Price at a Builders Merchants - Get Price from Two Companies


Jewson (by example) might offer your concrete blocks (best price) for 68 pence each. If you then ring up Travis Perkins (by example) and say that Jewson will do them for 68 pence then they will either say:


  1. "Thats a really good price we can't match that"
  2. "We can do them for 65 pence"
You can even then go back to Jewson with the new lower price from Travis Perkins and see if they will beter it. In short it is very time consuming so it is best to email list to each Builders Merchants.


Getting the Best Price at a Builders Merchants - Delivery


After you have your best price, ask for free delivery. This is an added bonus that is nearly always included for fairly large orders. 


Getting the Best Price at a Builders Merchants - Get the Quote in Writing


It is very important that you get the price or quote in writing. If you just talk to somebody over the phone, then that is not good enough. You may not get that price when you pay! Which would be annoying.

Also if you have a credit account (see notes below) then you will not pay for maybe a month, by which point you will need you email to check the bill or invoice, against your quote. 


Getting the Best Price at a Builders Merchants - Check Price


If you are paying cash or card on the day then then obviously check the price as you normally would. But if you pay by invoice then make sure when the invoice arrives (may be 2 weeks after receiving the goods) that you check the prices. They sometimes may have doubled! And you will be very glad you have your quote in writing (email). 


Getting the Best Price at a Builders Merchants - Credit Accounts



Where things really fall apart is the accounting. You might think a credit account is a handy thing to have, but you will be harassed (record is 8 emails and 2 calls over 10 working day period) by their "partner" credit management companies, to pay the bills pretty much from the word go. Even for small bills under £100. . . 

Personally I try to make money by actually working and doing things, not skivvying around trying please somebody in a call centre. 

Jewson for example will not email invoices to you so you can check them easily, instead its masses of paper, or some inconvenient online portal where you can log on (yes another password to remember) to view them.


Getting the Best Price at a Builders Merchants - Conclusion


For large orders a builders merchants can save you a lot of money. However, these guys make buying something time consuming. This may be worth it for large order but for small bits and bobs, you may prefer to  go to B&Q or Homebase. 

Always look out for special offers in Homebase or B&Q, they are often cheaper than a Builders Merchants.



Wednesday, 21 February 2018

Does Microsoft Office USe Multiple Cores?

Does Microsoft Office Use Multiple Cores?


Having recently upgraded from a 4 core to 8 core system, I am wondering how well access (by example) uses multiple cores.

So whilst transferring a 65,0000 entry access database to excel, I have observed the below CPU behaviour.


So besides showing I need more memory, the performance monitor shows that work load is spread over 4 cores, possibly 5.

Changing priority of the process does not change this spread. A lot of people say that you don't need more than 4 cores unless you are doing crazy rendering or editing. They are probably right!

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Monday, 19 February 2018

Scythe SY1225SL12L 120mm Review

Scythe SY1225SL12L 120mm Review - Intro


Around 2 years ago I decided to make my PC quieter by using 2 Scythe SY1225SL12L 120mm Fans to replace the main chassi fan and also to replace 2 smaller CPU cooler fans.


Very Normal Looking

I run a HP XW8400 with two dual core processors, with thermal output of 60W a piece. This arrangement worked well for 2 years. I occasionally run CPU intensive models, the rest of the time its just multitasking and PDF making.

Scythe SY1225SL12L 120mm Review - Noise Levels


The fan is almost silent run at 12V this fan spins at 800 rpm. It is so quiet you have to listen hard even to hear it. It is quieter than the Arctic Cooling F12. But the air flow is lower. . . . regardless of specs, you do not feel much air going through case with these fans. After a switch back to Artic Cooling F12 there was a notable draft going through the case.

Cobwebs - The BAdge of Long Service


Scythe SY1225SL12L 120mm Review - Cooling


As mentioned above one of these Scythe SY1225SL12L will adequately cool 2 60W processors under light use. It will not cool 2 x 120W processors. I recently upgraded to 2 quad cores and even at idle the fan could not dissipate that much heat.


Scythe SY1225SL12L 120mm Review - Conclusion


The Scythe SY1225SL12L is a well made, excellent value fan, which is virtually silent. It is a great options for those wishing to build a nearly silent PC.

0.03A - Very Small Power Consumption

The fan is quite partly because of the design of the thing, but mostly because it spins a lot slower than most fans. As it spins slower it moves less air. If you are using over a 100W processor then chances are you will need more air flow, even when run on 12V.

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Friday, 2 February 2018

Reinforced Retaining Wall

Reinforced Retaining Wall - Intro 


This a a quick post to show some pictures of a reinforced retaining wall, along with a little non technical description, along the way.

A retaining wall is generally a wall you would build to avoid having a steep slope, or where you want to have a change in ground levels without a slope. Opting for a step instead. Retaining walls can be just a few feet high, or many meters.

Reinforced Retaining Wall - Basic Concept


If you were to stand a domino on its end, it could be easily pushed over. If however, you were to super glue the domino to a heavy table, it would a a lot harder to push over. Provided the glue were strong enough you would have to tip the table over to get the domino to topple.

In the same sense a concrete wall, can be easily pushed over by heavy soil pushing against it from one side, so we must attached the concrete wall to something heavy to stop it moving.


So we anchor the concrete block wall to a concrete slab. This is done by setting steel bars in the concrete footing, as shown above. The soil will try to push the wall, but with the weight of footing and the soil resting on top of the footing it will not move (providing the soil under the footing is not too squishy - a geotechnical investigation would determine this).

It is also important to let the ground water drain out from behind the wall. Gaps or pipes must be included to allow this.


Reinforced Retaining Wall - Case Study


In the below picture you can see the footing for the retaining wall has been cast, and the steel bars (rebar) are left poking up, ready for the wall to be attached to.



Next up the block wall is built up around the rebar. The block are hollow as they will be filled with concrete at a later date. Another option would be to build a wooden mould (shuttering) around the rebar and pour concrete in to the mould to make  wall.


As the wall is built horizontal bars are added, these are tied with thin wire to the vertical bars to keep them in place.


You can see here how the wall is built to one side of the footing. This helps keep the wall stable, as it will be loaded from (in this picture) the left hand side.


You can see more clearly here the thin wire sued to hold the bars in place prior to pouring the concrete.


On a very long wall such as this one you will need to have expansion gaps, these are breaks in the wall filled with squashy (compressible) material that allow the wall the  expand and shrink when it get hotter and colder.

Reinforced Retaining Wall - A Simple DIY Design

This retaining wall as pictured was likley designed by an engineer. And it is next to a railway so it is a very high quality, probably over specified retaining wall. 

For DIY purposes retaining walls can be built without reinforcement, from normal concrete blocks sometimes without any footings. But drainage is still very important. 

A method I have tried is a a thin strip footing topped with a concrete block wall. The blocks are laid on there side, and can be sloped gently back towards higher ground. If you do slope the wall back fill as you go. Gently pack the soil behind the wall. Every 4 or 5 block insert a length of 50mm drainage pipe between the blocks to allow of drainage. 

Wednesday, 17 January 2018

Shimano V Brake Pads / Shoes / Blocks Compared

Shimano V Brake Pads / Shoes / Blocks Compared - Intro


Shimano make  V Brake Pads / Shoes / Blocks with a number of different compounds. This compound can be softer of harder for example to suite different rim types. Each Pad / Shoe / Block, has its own model number so you can find out which you prefer.

Shimano V Brake Pads / Shoes / Blocks Compared - Threaded 

The Below Pads have a Threaded Fitting

M70T3

70mm - Threaded Type - Performs especially well in wet conditions and may pass DIN standards. Gives off less noise, but the pad is heavier, faster rim wear and tends to fade.

M70T4 & M70W


70mm  - Threaded Type - Only for side wall machined rims. Performs especially well in wet conditions and may pass DIN standard. Tend to be low noise, low rim wear and fade.

S70T & S65T


60mm or 70mm - Performs well in dry conditions and tends to be low noise. Wears in muddy conditions

Shimano V Brake Pads / Shoes / Blocks Compared  - Un-Threaded


The below pads have an UN-Threaded Fitting

M70T2 


70mm - Performs especially well in wet conditions and may pass DIN standards. Gives off less noise, but the pad is heavier, faster rim wear and tends to fade.

M65T & M55T


65mm & 55mm - Un-Threaded - Performs especially well in wet conditions and may pass DIN standards. Faster rim wear and tends to fade.

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Tuesday, 9 January 2018

Top 5 Class D Amplifier Boards

Top 5 Class D Amplifier Boards - Intro


This page title should also have "low cost" added. All of the below boards cost less than £8 / $10, so make for a very low cost project, just be aware you will need to power these boards, and for the louder options below this can cost 2 or 3 times the cost of the board itself.

The below descriptions are boards I have owned and tried. All chips (8403, 8610 etc.) will behave differently depending on the boards used. For example if a specification says 24V, but you board has 22v capacitors, then you will not be able to run the max voltage.

Also just because a board has more capacitors and knobs on it does not mean the chip will be louder or better. The best results I find come from the most simple boards.

Top 5 Class D Amplifier Boards - 1 - PAM8403


Cost: £1 / $2
Voltage: 2.5V to 5V
Output: 2 x 3W

The top slot goes to the the PAM8403, this is the size of a postage stamp, and you can run it from a USB power supply, or 3 x AA batteries or a single lithium cell.

Its power is rated at 3W, but it is incredibly efficient, producing a room full of sound, when using 4ohm speakers.

My favorite class d amplifier, fiddly but fiesty!


If you have an old hi-fi speaker of any sort hanging around you could convert it to an active speaker, for perhaps just £2 / $4.

I have placed this board at number 1, because it is:


  • A versatile low cost amplifier
  • Very easy to power
  • Very very efficient
  • Good quality sound at all volumes
  • A lot of volume when considering low cost of board and power supply. 
Note: You can not run 1 speaker from this amplifier, both of the outputs have to be used to avoid damage to the chip. I have run a tweeter from left and woofer from right to get around this which is OK.

Top 5 Class D Amplifier Boards - 2 - PAM8610



Cost: £2 / $4
Voltage: 8V to 15V
Output: 2 x 15W


Second place, but only just. 

The PAM8610 is the logical step up from the PAM8403, it requires a higher voltage to work, and the low volume sound quality is not overly good, but it produces a very high volume for such a small amplifier. Get the basic board if you are buying with no heatsink or volume control, you do not need one. 



These is s light deterioration in sound quality at low volumes which some might find annoying. This can be well powered from 8 x AA batteries, or a cheap 12V wall socket transformer.  If you are running this amplifier from a SLA or Car Battery be a bit careful, because these sometime creep over 15V with some chargers. 


Top 5 Class D Amplifier Boards - 3 - TPA3116 


Cost: £5 / $10
Voltage: 8V to 24V
Output: 2 x 50W (Official) 2 x 15W (Real World)


This amplifier is comparable in output to the PAM8610, the sound is a lot cleaner to. But this is offset by the difficultly in proving 24V to power it adequately, it will work from 8V but you will have very low power levels until you reach 18V upwards.

I tried a complex 3 channel board, perhaps give a simple one a go.


That being said this is a versatile amplifier that will run on a very wide voltage range. The sound is crisp and clear at all volume levels, although high volume sound will be distorted if you are using an under powered supply. 

I used a 3 channel variant of this board which is so say 50 + 50 +100W, but is no where near this loud. Perhaps the board which uses NE5532 pre amplifiers. And the gain is fairly low.

Top 5 Class D Amplifier Boards - 4 - TDA2030

Cost: £3 / $6
Voltage: 8V to 16V - Will go higher on some boards. 
Output: 2 x 50W (Official) 2 x 15W (Real World)

This is actually a AB class amplifier, which is fairly inefficient. However it is small and cheap and reasonably easy to power. The sound is far richer than any of the above amplifiers, with a warm sound many will fine pleasant. 

It is not great for running from AA batteries but will run well from an SLA battery. It cannot be run from AA batteries as the power requirement is to high. 


Top 5 Class D Amplifier Boards - 5 - OEP3W or XTP8871

Cost: £1 / $2
Voltage: 2.5V to 5V 
Output: 3W Mono / 5 W Mono

I couldn't quite decide between these two they are both excellent boards that they can be powered from a USB port, requiring only 1A of power. Mono is easily achieved my mash together the positive and negative input wire. You then one have to find one speaker to use these amps, which lowers the costs still further. 



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TPA3116 Amplifier - Power Supply

TPA3116 Amplifier - Power Supply - Intro


I am not an electrical engineer. Perhaps this is why I have tried this amplifier with 5 different power supply options. Including 12V, 15V, 20V, 24V  all have worked to some extent. Which shows this amp although needing a hefty power supply to produce loud music will, produce varying volumes from all different types of supply provided they are within spec voltages of 6V to 24V.

System: This is based on the 2 chip 2.1 board with NE5335 pre-amps. My input source was an Iphone 6, connected via a good old fashioned aux cable, via the 3.5mm headphone socket.

TPA3116 Amplifier - Power Supply - 12V 2A Wall Socket Power Supply

This worked OK, but the volume was very low. The sound was perfectly clean, noy problems really but very underwhelming volume.

12V 2A - Cheap and Works to an Extent

TPA3116 Amplifier - Power Supply - 12V SLA


I have tried this amplifier on 2 types of lithium batty which are design to replace SLAs, the shido LTX9-BS and the EV Power 7ah 12v LiFePo4 Pack.

The Shido LTX9-BS is the closest match to a true SLA as it gives out many many amps peak current. Powered by this SLA equivalent the TPA3116 gives out clean rich sound at a fairly low volume. Perfectly adequate for a lounge listening, or for speaker computers for example, but certainly not party loud.


SLA or Alternative OK for Low Volume


TPA3116 Amplifier - Power Supply - 12V to 24V Transformer from SLA


I have also tried a "Fulree" Step-Up converter, rated at 3A this gives more gain for lower input volume, but I suspect the 3A max current is not high enough to support the TPA3116 at high volumes.

I have tried this 12V - 24V Step-Up converter powered from the above Shido battery and also powered from a 20V 90W (4.5A) IBM Thinkpad Power Supply.

The TPA3116 will cut out (I Think) if it is not getting enough current. I have arrived at this conclusion because whilst using the 12V - 24V Step-Up converter, the cut out occured at a lower volume when running from 12V than it did at 20V.

The 12V - 24V Step-Up converter supplies more current if it has to make up for smaller differences in voltage, so a lower volume cut out when supplying less amps would suggest a current cut out are caused by low current. The step up converter does com,e in a 10A variant which would be a better choice.

10A Variant preferable to 3A Version

TPA3116 Amplifier - Power Supply - 20V 4.5A Laptop Power Brick


At 20V this amplifier really starts to shine. The input source (Iphone) can be turned up to full volume with very little distortion. You also begin to feel the bass rather then just hear it. The sound is clean and crisp, and there is little or no hiss.

The good news about this power supply is that you probably already have one! Most laptop bricks run 19V or 20V, and although some may only kick out 2A this will be fine for a board with a single TPA3116 chip.

If you do not have one then I would suggest search for a "Thinkpad T60" power adaptor, they are 20V 4.5A and sell for £6 / $10 including shipping.

Excellent Sound - Feel the Bass - Excellent Value

TPA3116 Amplifier - Power Supply - 24V 6A Power Brick


I had to max this thing out, so I went for the 24V 6A "Minger" power brick that is available on Ebay and Amazon. After all I had tried nearly every other power source! So why not one more to make a good blog post.

24V power brick are quite expensive compared to 20V one, I had to pay £16 / $25 for this supply.


For Maximum Power and Higher Low Input Gain. 
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Tuesday, 2 January 2018

SPL10M.1 Review & Observations

SPL10M.1 Review & Observations - Intro


The cheapest 10" driver on ebay lead me to the SPL10M.1, this is a large speaker and is certainly heavy but is not a sub woofer. It is just a very large mid-bass driver. It is very well built, I paid under £20 for this peaker, and it is excellent value. But it has a weird spec!



I am not sure why it is so large, but for a low power application as I intend using a TP3116D2 amplifier I assumed it would be OK.



SPL10M.1 Review & Observations - Out of the Box


First things is that it is heavy. Second thing is that is built OK. The spring terminals have a reasonably high quality feel, and the materials look well finished. The cone is paper, rather then fancy new fangled material, but this is fine as I have used some very good speakers that have paper cones in the past. The stainless steel thing in middle of the speaker (phase plug?) is a high quality feature, at least aesthetically.



The box itself is a bit disappointing with little protection offered to the speaker. However at the price I bought this I doubt they wanted to spend extra ££ on wrapping!

SPL10M.1 Review & Observations - Performance

I have powered this up to around 50W with low frequency sound (it is not design for this) but performs well. I will attempt to describe the sound, but I am pleased with the purchase.


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TPA3116D2 2.1 - Observations

2.1 Channel TPA3116D2 - Observations - Intro


I have recently purchased a TPA3116D2 from ebay, it is a 2.1 channel variant. So it uses two chips one for stereo and the other for a subwoofer.

Official specs put a single TPA3116D2 amplifier at 100w or 2 x 50w (depending on configuration).

This is wildly optimistic as a power rating, at 20V this board will make about 30W, at 24v it swill draw around 40W. Remember this is for Two TPA3116 chips, so if you have a single chip variant you can expect half the wattage!

The sound is still very full and loud, so this amp is no doubt efficient but why even the official specs talk of 50W per channel I do not know.

Do not be swayed for your choice, this amp does give good sound and these days even a 3W per channel amp such as the PAM8403, can sound good.

2.1 Channel TPA3116D2 - My Board (From Ebay)


2.1 Channel TPA3116D2 - Observations - Power Supply Choice

For in depth view of TPA3116 power supplies

The 2.1 Channel TPA3116D2 apparently will produce 100w output at 21v in to a 4ohm speaker. This would point at a power supply being rated at 5A for a single chip. However you will not need a 5A  power supply because the specs for this amplifier are inaccurate. A 2A power supply for a single chip amp and a 4A supply for a dual chip will likley suffice.

If you are  running the 2.1 Channel TPA3116D2  at lower voltages I have noticed the following:

12V / 2A - A wall adaptor used for power provided clean sound at max volume. The max volume was reasonably low however. This was tested using 6 ohm speakers.

14V / 7A - Using a lithium 12v battery pack with a rated output of 7A (fresh off charge = 14v). This provided more volume but lots of distortion much above 60% volume. Thus used 4ohm speakers for stereo and a large 10" 4 ohm woofer for sub.

Note - If you are planning on using 2 x SLA batteries at 12v a piece be careful. Although these are labelled at 12v, often they will hold 15v when fresh off the charger. So it is possible to accidentally supply your TPA3116D2  with 30v which would not be a good idea.


Choose Voltage Carefully - 22V to 24V to avoid disappointment


2.1 Channel TPA3116D2 - Observations - Output

When running a a 4ohm load at maximum volume, with a 20V 4A supply this amplifier draws 30W. Does this mean that this amp is really 30W RMS? I measured this with a wall socket watt meter.

I was expecting some serious output from this amp. I have used 20W (2x10 @8ohm/12v) PAM8610 which  runs on AA batteries, and running this board at a similar voltage, the PAM8610 wins hands down. The PAM8610 is I would suggest a much more efficient chip (?) although my electrical knowledge  is limited.

To power this amplifier to a level where it begins to shine you will need a 20v supply, have a look at some of your old laptop adaptors! They may be perfect. I do not think you will need a very high amperage adaptor. 4A should be plenty. 

2.1 Channel TPA3116D2 - Observations - My Build

I was expecting a great deal of power from this amp, so I built a very large speaker. I used:


  • 2 x 8 Ohm Tweeters*
  • 2 x 8 Ohm Mid Range* (30W rating)
  • 1 x 4 Ohm Woofer (SPL10m.1) (75W rating)
*These are linked in parallel, to give 4 Ohm load. The tweeters have a high pass crossover in form of capacitor. 

I built these in to a 15mm plywood box, which stands around 60cm tall, and requires handles to lift. Most of the weight comes from the wood and and the SPL10.1 which weighs a few kilos on its own! The midrange speaker has their own enclosure inside, to prevent the woofer from influencing them.

I used a pice of plate steel to to mount the amplifier board, using just the potentiometer bolts to secure it. I then cut an extra hole for a plate with RCA connectors. Lastly after first experiments with batteries I installed a IBM think pad power supply which give 20V 4A Supply.

I used a piece of fabric we had lying about to cover the front of the speaker, as I want a neutral "furniture" type look for the thing.

My most pleasing design choice was the use of a piece of 100mm waste pipe for a bass port, this runs side to side at the top of the enclosure, the opening can be used for hand holds for carrying the the speaker.

2.1 Channel TPA3116D2 - Observations - Sound and Performance

Powered at 20V with 4 ohm loads the sound is fine for loud personal listening. The range of sound is really great, the low frequency oomph being the most pleasing feature. The bass will travel throughout the entire house and vibrates things of shelves nearby. 

The amplifier is not very loud when listening to bass free music, it reserves 50% of it power just for bass, so listening to say vocal rich music is a little underwhelming, although the sound is very crisp and clear at all volumes. 

The sound quality I would rate as excellent, however a bit more quantity would be nice! Especially as the Texas Instruments specs are nearly 600% out. 

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