Chienmortbb

Sorry for the delays in updating this thread but the "infection" was in fact a secondary Cancer so have the whole cycle starts again. I have made some progress and will post more with pictures soon,

Fans don't have to be noisy. The problem is that to keep costs down, cheap fans are often fitted to commercial amplifiers. Fans are electromechanical devices and hence less reliable than electronic components. However the trick is to chose a fan that is higher voltage than the standard fit and run it at the lower voltage. This means tha fan will run slower and will last longer. It will not move as much air as. If it were run at rated voltage but it will be much quieter and more reliable. Of course the other problem is that many lower power also have insufficient heatsinks. Valve amps do get round most of theses problems BUT many are very noisy/hissy, so you cannot just assume that valves are the magic bullet.

[quote name='ubit' timestamp='1420132314' post='2645964'] Harke VX250, just the worst sound ever. Thin and broke up at volume. Interestingly, I had an Ashdown Mag 200 combo and I loved it, so maybe all their stuff ain't pants [/quote]i had. Later nag 300 with a 15". Should have kept it but the MAG200 was One of the Early UK made Ashfowns.

[quote name='JTUK' timestamp='1359668876' post='1958658'] Carldro and HH are a given but add to that PV and it is no excuse that they are bombproof, IMO.... they still sound sh*te.. Worse experience in recent times was a GK RB combo.... followed by plugging my cabs into an Ashdown MAG thing...and getting nothing usable...at all. [/quote]maybe your cab (runs and hides)?

I would not use jacks for speaker fans for the following reasons: 1. Most sockets and plugs are rated for 3 amps or fewer. That is about 90 watts into 8 ohms. 2, There are 5 and 10 amp plugs and those are non switched types. 3. Because Jack plugs have exposed contacts, they are prone to short circuiting the amp output. One One power amp manufacturer told me that in MI, shorted jacks were the largest single cause of power amp failures. 4. As the cables can be used for either instrument or speakers, the two types of cable are quite different. A speaker cable is not good for instruments as there is no screening and an instrument cable will not be able to take the current and may cause a badly designed amp to oscillate. If you feel you must use Jacks, switchcraft and nuetrik both make square bodied jacks withe the terminals at the end that are sealed. Cliff make a more traditional Jack with a dust seal that should be fairly airtight. Of course the Soeakon was designed for high current use and the contacts are hidden on both plug and socket so it is really hard to cause an external short circuit.

[quote name='Oldman' timestamp='1375884252' post='2166909'] One of the problem is its all RRP, TecAmp dictate the selling price, discount at your peril and your pocket. [/quote] If that is true them Tecamp are breaking the law. Once you sell on a product you cannot dictate its selling price and you cannot take sanctions against a desler or agent for any reason other than non payment of goods..

[quote name='Beer of the Bass' timestamp='1418463754' post='2630354'] That looks like a good deal, and it's nice and compact. I have the Connex SMPS800RE and the 600 watt IRS2092 power module. While having a conservatively rated power supply could be a good thing, my modules work out a fair bit larger than this integrated module so they're not going to make for as compact an amp. If I hadn't already bought the Connex modules I'd have been considering that one, especially as they're available in Europe and have decent documentation. [/quote] That supply is well know in DIY HiFi circles and has a great reputation. I don't think you will regret buying the Connex units.

A one dB hump is nothing. 1dB is what is known in engineering terms as a JND or just noticeable difference. However that is in controlled conditions where Ambient noise is low and controlled. I don't know if any musical performs fe where that is the case. In normal use no one can hear 1dB.

[quote name='Beer of the Bass' timestamp='1418382969' post='2629696'] I have a couple of Connex modules for a project that I've been meaning to get on with (not having a gigging band has made it less of a priority). I haven't wired them up yet, but they look well put together. Their response to emails can be slow (apparently this is normal when dealing directly with Chinese companies) and their documentation isn't as good as some manufacturers - for example I still don't know the input sensitivity of the power amp and I'm going to have to work it out for myself by measuring the gain. Their prices are very good though! [/quote]The Connex modules get a really good press as I said but I was put off by my previous experience with them.I eventually went with the Boyoho MY1-251PA, mainly because of the pre sales support that I got from Michel at Smart and responses from the Boyoho factory. As I said at the start of the thread, part of the inspiration was the 1 X 12 Cab Build. I modeled the Beyma SM212 speaker and in the proposed cabinet and tuning, the maximum SPL is achieved at about 230 watts. So 250W into 8 and 500W into 4 ohms was the target. The fact that the amp is capable of driving double the power into 4 ohms compared to 8 ohms means that the power supply is beefy enough for the task. In fact the power supply is rated at 600W. This allows a full 250W to be put into two 1x12 cabs. Compare this to say the Hartke 3500 where the power into 8 ohms is 250W but only 350W into 4 ohms. Clearly the power supply in the Hartke limits the total power output.

Yes I got the Boyoho MY1-251PA. Cost is £109.66 for the amp, £3.94 for the cable set and £12.62 postage form the Netherlands. So £126.22 although this can change as the £/€ exchange rate changes. http://stores.ebay.co.uk/Class-dmodule or you can contact them by email to order. They also do a 150/300 module at about £90 and couple of dual channel ones that can be bridged for higher outputs.

[IMG]http://i57.tinypic.com/and01l.jpg[/IMG]

Thanks to passinwind for keeping this thread going. My wife has picked up a post op infection and we have both had Man Flu (her words not mine). The PCBs are superb quality and although there are cheaper suppliers, OSH Park really have a quality product. Since my last post I have chosen and purchsed the power unit. I looked at all the usual candidates for an integrated Power Amp and Switched Mode Power Supply. As a recap my minimum spec was:[list=1] [*]Power Output 250 Watts into 8 ohms at less than 1% distortion [*]Power Output 500 Watts into 4 ohms at less than 1% distortion. [/list] The manufacturers looked at were:[list] [*]ICEPower (B & O) [*]Anaview/Abletec [*]Connexelectronic [*]BoYoHo [/list] ICEPower are probably the market leaders and supply to many manufacturers including Kustom for Bass Amps. ICE Power only supply OEM (Original Equipment Manufacturer). They are difficult to get in the UK and most of them for sale on EBAY are from the USA. As already outlined, import costs make the ICEPower very expensive in the UK. Anaview are the power units for many too including Ashdown. They are available from Profusion in the UK but a price rise just before I ordered meant that I could not afford the Anaview unit I would have liked. Connex Electronic are a small Chinese company that has built a very good reputation for quality and price in HiF circles. They have a few likely cndidates in their range but when I tried to order another item from them before, my order was refusd and my money refunded as I was blamed for a flame war against them started by another Brit. Connex products are distributed in Europe but none of the distributors stock the integrated modules. BoHoYo are another Chinese Company, seemingly bigger than Connex and have a European Distributor in the Netherlands. Smart Audio.

The so called FMV (Fendrer Marshall Vox) stack is not very versatile as they are passive but then if you are building a Valve pre then maybe that is OK. The Fender stack will give a result like a Fender Bassman. One problem with the Fender stack is that it is possible to kill the volume with the wrong pot setting, not a good idea on a dark stage.. The Vox version is quite inflexible and of these the Marshall is the best bet of the three. Again the James would be the choice for a simple Bass & Treble control, Baxandall needs to be included in the feedback loop of an amplified stage so will add to the number of valves. One comment, most of the Valve sound comes from the power amp and power supply, is it worth putting valves in the peamp?

[quote name='LukeFRC' timestamp='1415346050' post='2599350'] hey there! rescuing this from the second page... also pointing out that if you go into the TKS sub forum and look at their ex trial speakers threads they've got 4 of the Beyma drivers that the 3 musketeers are using... [/quote]SubsonicSimpleton(Andy) and I eould like one each and if anyome else is interested please PM Me or SubsonicSimpleton.

To be honest 6V6 I am glad you are on board. Charlie and I are both Electronic Engineers by trade and it is great to hear other opinions, even if you don't always agree with them initially. I will post a few more pictures of the case innards and the preamp PCBs tomorrow and I am close to choosing my power amp.

[quote name='SubsonicSimpleton' timestamp='1415371064' post='2599707'] I would really like to try the Beymas, but I can't afford to buy all 4 atm, posting here so other interested parties can contact me by PM if they want to arrange a group buy. [/quote]I am up for one if you go for them. If you have a PayPal account I will send you the money.

Just to clear things up a little, this was never meant to be a build your own bass amp thread, I was just wanting to explain the thinking behind how I am going about specing my own home brew amp. It is a learning process and I thought others could learn along with me, just as I learnt from the 1 X 12 Cab build diary. If everyone is happy with that I will continue.

The case for the defence? [IMG]http://i59.tinypic.com/2zhqdk5.jpg[/IMG]

Yes my old HH amps had a mid centered on 650Hz and I have got used to that so the mid control will be switchable on mine. Now stevie has shown me how to put pictures up, I will start tomorrow but in the meantime I will elaborate on the stages of the "preamp".[list=1] [*]Input gain stage and active bass and midrange control, optimized for active basses -[i] I will be modifying this to take passive basses although many passive basses have been played througn the preamp and I hear that they sound great.[/i] [*]Parametric equalizer. [i]- This is a fully parametric EQ with contol over Frequency, Q, and Level[/i]. [i]The Semi-parametric EQs as fitted to many commercial amps have fixed Q.[/i] [*]Passive treble control, boost/cut. [i]I believe that the The passive treble control is less noisy than an active one and more musical but [b]perhaps Charlie could comment.[/b][/i] [*]Effects send/receive/aux input. - [i]Hopefully needs no explanation.[/i] [*]Variable high pass filter, 2nd order fixed + 2nd order variable - [i]Think of a Thumpinator or FDeck's HPF. Has the dual purpose of controlling excessive cone movement below a cabinet's tuned frequency and also taking the "boom" out of those nasty rooms.[/i] [*]Final gain stage/line driver - [i]The output stage to the Power Amp[/i] . [/list] More tomorrow.

[quote name='Chienmortbb' timestamp='1415090767' post='2596464'] [url="https://www.dropbox.com/s/6hle9nv088nxx72/2014-11-02%2021.16.53.jpg"]https://www.dropbox....%2021.16.53.jpg[/url] OK I have tried several way of uploading for ages and have failed. Help anyone? [/quote]

The commercial amp builder will buy everything in bulk and will often fit lesser parts because the difference in performance will not be very much. The DIY builder will not compromise and that costs. The one thing any DIY amp builder will tell you is not to start it because you want to save money. It will be more expensive than a shop bought amp. I was reminded of this today. Last week Charlie sent the PCBs for the preamps (5 boards and a few assorted parts). Each of the PCBs costs about £13 but they are really good quality. He also got some Bourns Cermet pots from Ebay that retail at about £10 each, for a really low price. He added those to the package and I got the card from Royal Mail to say they had arrived. Great but the downside is that I have been stung with £14.30 for Customs Charges and an £8.00 handling fee by Royal Mail. Be aware that if you buy from outside the EU ( i.e. USA or China) you will get stung. They add postage and anythng above about £15 has 20% VAT added to it. There is another limit (about £136 I think) where import duty is added. So watch those "bargains" from abroad.

[quote name='6v6' timestamp='1414834220' post='2593727'] So, to clarify, it's pretty likely to be impossible to modify an ATX SMPS which outputs 5 and 12v to give the necessary voltage swing. The other issue is SMPS technology is really complex, and well beyond what even pretty experienced electronics DIYers are likely to be able to modify (particularly if, as in this case, it'd effectively be redesigning the whole power supply..) That complexity is one reason why I personally prefer simple traditional power supplies and either valve or mosfet amplifiers - it's just much more accessible to a hobbyist and if it breaks, I stand a reasonable chance of fixing it, which is unlikely to be the case with either SMPS or class D technology (not saying it can't be done, just that it's really hard for non experts without specialist equipment and knowledge) [/quote]One of the debates I have been having with myself is whether to go SMPS for the power supply or transformer. Of course the weight will be higher with a TX but the complexity will be lower. In general, fewer components means higher reliability. As has already been mentioned, several companies make combined Class D with Switched Mode Power Supply modules. ICEPower, Powersoft, Anaview/Abletech Pascal and numerous Chinese manufacturers.They are great but also in some ways they are restricting. As for Class D amps, they are now much easier to to understand and many hobbyists now design their own. However I am not going to do that.

Some of you may have come across Class T amplifiers. There is no Class T but some people use this to denote amplifiers using Tripath technology. Tripath were Class D innovators (sadly the company is now defunct). Tripath had their chips made in the far east by third parties and they are still manufacturing those designs. They are now old technology and are really Class D.

Most SMPS power supplies can be adjusted +/- 10% so the 12V supply could go to 13.2V but that is not much. A PC power supply ony has a lot of power available from the +12V rail. The -12V rail often has only 0.5A and the 5V line 1A or 2A. With a 12V rail, the maximum you can get with reasonable distortion figures is 4.5 watts into 4 ohms ( in the old days all car stereos were 4-5 watts per channel). You could connect two amps in Bridge Mode to get 9 watts into 8 ohms and four amps in Parallel Bridge Mode to give 18 watts into 8 ohm. Your car stereo will probably say much higher figures and I will cover that later. Suffice to say that the above figures are calculated from the physics or the limitations of semiconductors. So we need more power and that means more voltage. In my opinion you need at least 80V or (40V-0-40V) . This gives 200W into 4 Ohms, 400W into 8 ohms Bridged and 800W into 8 ohms Parallel Bridged.

Power supplies can be either limear of switch mode. Linear power supplies use a transformer to down convert the 230V ac mains into a more usable voltage, they are simple but the downside is the weight. SMPS or Switch Mode Power Supplies do not require a large heavy transformer but are more complex. Like Class D amps, grat care must br taken avoid RFI/EMI interference with audio equipment. So the options are to have separate amplifiers and power suppliy or an integrated unit.