Chienmortbb

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.

I expect some tough questions from Stevie after my posts on the 1 x 12 Cab diary but hopefully I can give the reason for my choices and who knows a good argument may lead to a change of direction but we will see. The spec is taking longer that I expected ( or rather hoped so ) I will answer some of the questions that have already been put. Firstly the second build is already planned and it will be a no compromise rack mounted version of this project. The pre amp will have a separate power supply along the lines of passinwind's 500 watter on TB. However back to this design. The power amp As with the preamp, the power amp is not one circuit element but several. All basic power amps can be broken down into the amplifier section and the power supply. The amplifier section will be a Class D amplifier. There are several myths and misconceptions about Class D amplifiers. The first is that D stands for Digital. Amplifiers classes were named in order of their development. Class D amplifiers are switching amplifiers where the output mosfets (metal–oxide–semiconductor field-effect transistor) are driven by a PWM (Pulse Width Modulated) waveform that is analogous to the input audio signal. As a switching amplifier, Class D is very efficient with many amplifiers outputing 90%+ of the input power as audio. Amplifier Classes go from A to H but not all are suitable for Audio. Classes that are suitable are A, B, AB, D, G and H. All these classes can be implemented with Valves, Transistors or MOSFETs but fir Class D the ususl cloise is thr Poeer MOSFET. Sll commercial Class D amplifiers use MOSFETs,

Thank you to for the encouragement. The detailed design spec is not complete but the following are planned: 1. All Solid State with a Class D power amplifier topology. The main reason is that Class D makes for easier thermal management,.To put it bluntly it is easier to keep cool. 2. Power output a minimum of either 250 Watts Average into 8 ohms and 500 Watts Average into 4 ohms or 2 X 250 (dual mono} into 8 ohms.Output on Speakons, no jacks for speakers. 3. Pre amp section. This was designed by Charlie Escher (passinwind on TalkBass) after several months discussion between him and me. Chalie has finished his amp but is constantly refining it.There is a short thread on TalkBass about Charlie's amp here http://www.talkbass.com/threads/a-diy-500-watt-bass-head.1061473/ Like Charlie, I will be adapting the design but with his knowledge and consent. I should false emphasise that although I hade many discussions with Charlie, he did the circuit design, modelling of circuit behavior and built an tweaked the first iteration of the circuit boards.It is his design. More tomorrow

I have taken inspiration from the 1 X 12 Cab Build Diary and as I am building my own amp, I thought other may like to watch the process and also read, and see, the reason I behind the choices I make. My wife is very ill at the moment so progress in the build will be slow but hopefully the choices and explanations will be interesting. I am also looking for feedback so feel free to wade in. At the end I will produce a precis of the thread so that no one has to wade through they whole thing. My next/first real post will be the specification.

[quote name='Phil Starr' timestamp='1414447874' post='2589471'] Fane describe the 10-300 as having a 'smooth' response and it is flatter than many 10's, most have a fairly prominent peak in the 1-4kHz range which gives the speakers colouration which sounds quite nice with bass, or maybe that peak is so ubiquitous we have just come to expect it. My confession is that I'm going out with the SM212's which are fairly flat but my graphic looks like the frequency response you get from a cheap Eminence stuffed into a too small a cab. The 10-300's just didn't sound very interesting with bass. Nothing wrong but they just lacked character. [/quote]My amp build will have both vaswitchable mid and full PEQ that way I can dial in old school but go flat if I want. It is harder to EQ out old school from a poor* speaker/cab combination than to dial it in from a relatively flat speaker system. Re the Fane 10-300, I think you are telling me they are great for PA then. If you do not go for ultimate extension, they give a tiny cabinet even with a tweeter.

Phil, I have only modelled the 10-300s so you are one up on me. Although with the frequency plot on the data sheet I am surprised they sound flat at the top end. Regarding the new 10-125 I agree it models like a dog and looking at the TS you can see why.

[quote name='Phil Starr' timestamp='1414136681' post='2586188'] Oh if you want something that does go lower than the Celestions then the Beyma SM110's look promising at a similar price. Be prepared to wait for delivery though [url="http://www.bluearan.com/index.php?id=BMASM110N&browsemode=category"]http://www.bluearan....semode=category[/url] There's a thread on here from someone (fleabag) who tried these speakers and had a positive result [url="http://basschat.co.uk/topic/235679-can-i-improve-my-cab-at-all/page__hl__beyma%20sm110__st__30"]http://basschat.co.u...20sm110__st__30[/url] [/quote]I was really excited when I first looked at the SM110. I have just done a quick winisd plot of the SM110. It has a great frequency response in a 40L box but xmax is exceeded in the at very low power (approx 75 watts) . This means that it is 3-6dB down at 70Hz. I will recheck later but at the moment the Fane 10-300 looks. a better bet

Many of the modles on the market such as Anaview, ICEpower and Pascal are more than up to bass but are expensive, even as OEM, so to make a cheap loud amps from those is difficult. To go really loud you need a really good power supply and that is usually big. You also need a bigger heatsink as a 500 W amp at 80% efficiency still creates 100+ watts of heat if driven at full power. To make your own including a power supply is difficult as a good switch mode power supply SMPS is much more difficult than making a Class D amp. If you use a tradition transformer power supply you will same some weight compared to a traditional Class A/B amp but not a massive amount. To design a class D amp with switching power supply is a massive task and requires totally different skills/thought process from traditional amps. If Hartke are doing their own, I admire them, but I would not be the early adopter.

True. I was trauned in Military Elevtronics and vibration testing was a big part of the QC regime. So tne three things against plate anps, heat, vibration and pneumatic integrity of the caninet makee wary of powered bass cabs. If you do go witn a plate amp I suggest an ICE power one as they really are road tested.

Every bass and every cab and every amp is 5h1t. Otherwise there would be no Basschat

Hypex are very good but very expensive. The miniDSP plate amps at [url="http://www.minidsp.com/products/plate-amplifiers"]http://www.minidsp.com/products/plate-amplifiers [/url] are worth a look and are good value for the ICEpower modules versions. I still question whether a plate amp is a good idea in a bass oriented cab though. My worry is that Powered PA cabs rarely go very low (forget the sales specs, there will be little below 100Hz) so the main problem is heat. Putting an amp in a bass cab is like running it permanently on a vibration test.

[quote name='wateroftyne' timestamp='1413812037' post='2582163'] And you are to be applauded. I like stuff to look pretty - it's in my nature. It also shows that the builder takes pride in it, too. [/quote]i quite agrre but beauty is in the eye of the beholder. Some of thise TKS cabs look great, while the slant fronted ones look like my old Dansette record player. One piece of retro I don't want to see again. However if they sound better than anything else I would buy them. Of course other eyes and ears are available.

My beef with some of the posts is that they are either subjective or totally off topic with respect to the original post, The main gist of the OP was: "I have a Barefaced Super 12T . It's a great sounding cab , But I can't stand the handles this is the 3rd time I've picked the cab up by the top handle and it has swung back and bashed me in the shines. I really don't think it needs those wheels" Almost alI the posts berating Barfaced have nothing to do with the palcement, or intended use of the top handle. I have seen posts of poor build quality but have only heard of one [b][i]failed[/i][/b] handle. As the handle was the starting point of the thread then that is on topic. Most of the other comments are not. Poor build quality would result in multiple failures but the handle failure is the first I have heard. I think many people confuse build quality with cosmetic appearance. Had any of the Barefaced cabinets had the problems of the same magnitude as the Ampeg PF500 amp (now on at least revision 7) , I could understand it but they don't. I do not like the look of the Ampeg Valve heads. i my opinion they are cosmetically very poor ( maybe they are just retro) gives no indication of the build quality or reliability. This has been a real bandwagon jumping session and the trouble is that different people are jumping on different wagons. What has the sound of the cabinet (a sound that many people like) or the look of the cabinet got to do with the placement (and misuse of) of one of the handles? Maybe if we all shut up Alex migh come on and chip in but to be honest, if I were him I would keep contact on a one to one basis with customers.

I think this thread was started by one of Alex Claber's aliases. They say there is no such thing as bad publicity and when you think how much Aquilar, TKS et al pay for their ads maybe that is right. It is a free country, If you want a Barefaced buy it, if not, don't. I would buy a Barefaced if I had the money. Flat is good as sound shaping, voicing, equalisation, or whatever the current name for it is, should be done in the preamp not the cabinet. As for the Handles, it is a compliment to Barefaced that the only criticism is the placement of the handle. Maybe Barefaced can put a User Manual saying: WARNING The Top Handle is intended to be used to assist wheeling the cabinet, not for lifting. Barefaced take no responsibility for injury caused buy misuse of the cabinet. Of course now someone will say "It is my Cabinet , I will do what I want with it"

[quote name='molan' timestamp='1412633128' post='2570712'] Slightly updated to weather the inevitable storm. . . [/quote]Surely TKS are introducing product now in the UK but are established in Sweden. We did not witness TKS's growing pains whilst we damn near saw the Placenta with Barefaced.