Chienmortbb

Now I would appreciate some suggestions. The system is very flexible. I can choose to switch various circuits in or out. So the questions I am going over are: 1. Should I have the HPF switchable? Pasdinwind dies but after using his amp for some months he leaves it on all the time. 2. Effects return can be configured as series or parallel. Most Amps are currently series but parallel allows some local control over the wet/dry signal mix. Oh and should those the switch and EFX return level control be on the front or back? 3. The Parametric EQ section gives me control of the mids from about 100Hz to. 2000Hz and of course this overlaps the fixed middle control. It is worth adding a switch to change the fixed mid frequency? It makes the amp more flexible but more complex. 4. Active/Passive switching and gain change. Passinwind has only active basses while I have currently only passive ones. At least one of my bases will be converted to active in the next few months with a variation of the two band MM preamp but I want to have the ability to have the two options. So two Jack sockets or one Jack plus an Active/Passive switch? I would appreciate any comments based on experience.

Ironically the omissions make for a more satisfying build. I am studying the circuit diagram/schematic more closely than I would if documentation were 100% and learning more as I go. The Pre amp board is now complete apart from the wiring. Some of the components are now mounted off board as the preamp was designed before the HPF/PEQ circuit and taking components off board allows us to configure the circuits to the best arrangement. Below is the picture of the completed board. It still needs to be wired but I will leave that until the front panel is complete. As you can imagine I am taking more time and care over the front panel as it will be on show more than the back panel.

[quote name='Phil Starr' timestamp='1436867829' post='2821446'] More news, one of the cabs is to be reviewed by Dan Veall, bass reviewer of Interactive Guitar Magazine http://www.iguitarmag.com/reviews/?issue=&brand=&producttype=Bass and of course Dood of this parish. At the present the Cab is about to wing it's way to Dan, or it will be once UPS collect it. It'll be great to have a professional and independent opinion of the cab and I'd like to thank Dan for taking the time to do this. [/quote] Having seen some of Dan's reviewsI think this is great news. On another matter. Stevie is comparing the cab to his own 15/6 cabinet. Can you tell us more about that cab? Is it your own design or based on ages boy plan. What drivers? Size and weight? By the way I thought I knew a bit about speaker design but have learned how much I did not know during this process. Thanks for the hard work and patience with me and others.

[quote name='Phil Starr' timestamp='1436867829' post='2821446'] More news, one of the cabs is to be reviewed by Dan Veall, bass reviewer of Interactive Guitar Magazine http://www.iguitarmag.com/reviews/?issue=&brand=&producttype=Bass and of course Dood of this parish. At the present the Cab is about to wing it's way to Dan, or it will be once UPS collect it. It'll be great to have a professional and independent opinion of the cab and I'd like to thank Dan for taking the time to do this. [/quote] Having seen some of Dan's reviewsI think this is great news. On another matter. Stevie is comparing the cab to his own 15/6 cabinet. Can you tell us more about that cab? Is it your own design or based on ages boy plan. What drivers? Size and weight? By the way I thought I knew a bit about speaker design but have learned how much I did not know during this process. Thanks for the hard work and patience with me and others.

[quote name='stevie' timestamp='1436712482' post='2820116'] I didn't carry out a full-range measurement, I'm afraid, which would have shown up an imbalance between the bass and midrange. I did a ground plane LF measurement and a gated mid/high measurement but couldn't join them together because the first one was not calibrated. In any case, you need to factor in the changes in frequency response from the cabinet being on the floor, which makes a gated measurement problematical because it relies on filtering out all reflections. I've found that an RTA works well for checking the sound balance of a speaker in situ, but I didn't do one when I had the speakers here. I do know that my own 15" + 8" is ruler- flat on the RTA, which suits me, although others may well prefer a mid-foward balance. I can have a closer look at this when the speaker makes its way over here again. [/quote] No problem. I would prefer a flat response but I have enough control on my amp to EQ it flat if need be. Incidentally what sort of frequencies do you consider Mids? I tend to think 400-800Hz but I think many think mids start much lower.

[quote name='Thunderpaws' timestamp='1436705945' post='2820047'] This all sounds like great progress. I wonder if the natural mid bump will help me punch through more against three guitars with my Genz Streamliner. I am drink rely going to make one of these. Time to start ordering parts. Where's best to get the driver from? Lots of hardwork from you guys, well done. Cheers, Garry [/quote] Looks like you have the same spell checker as me Gary. You can get them from Blue Aran they are about £75 plus postage. I am not sure whether they could offer a group buy but maybe I'm comjunvtion with the UK Distributor of Beyms they could do a deal. I will leave that to The three musketeers though.

Stevie/Phil Did your measurements show pronounced mids or is this something that has just shown up in real life testing?

I have started to assemble the preamp board, the one shown in all the pictures to date was the Rev 1.0 PCB that is going into my combo rebuild later. The preamp has all the resistors and the IC sockets installed and I will be installing all the capacitors tomorrow. The capacitors are last because they are tallest. Although there are three IC sockets, each IC has 2 operational amplifiers. So six gain stages but as the ICs are audiophile quality, and because Charlie (passinwind) tweeks over and over again for the best performance/noise figures going. Passinwind has designed Valve preamps for at least one well known bassist and although the EQ borrows from that design, he uses this solid state design himself in both the integrated 500W amp and the small form factor 700W design pictured in an earlier post.

To make things worse some UK manufacturers make 10" speakers that are much larger than 255mm.

To think this used to be a pint sized thread😜

15s are not slower but In general will have a lower output at the top end compared to a 10 from the same range.

As Lord Claber is doing a guitar cab soon we may well see a change. However seeing Pete Townsend using a mass of Fender combos at Glastonbury makes me wonder what is between the ears of some guitarists.

From memory, the SI (Systeme International) is the real name for the metric system. It has been used in the UK Engineering industry since the 1960s. I started college in 1968 and we never used the Imperial System. In engineering, mm is the preferred unit of measurement or metres for bigger items. I cannot remember seeing cm on a engineering drawing. However as I am old and of failing mental faculties (think plywood debacle) this may all be rubbish.

Passinwind built an ESP designed pre a few years ago that used a Fender style tone stack. I don't know what amp it was use with but I Seem to remember a Fender fan reported it was just like his old Fender Bassman. I will ask Charlie to respond later when he is awake.

Yesterday was Chemo day so I did not have time to upload the latest pics. Attached is the latest pic of the build. I have wired the mains and the speaker connections. I have added a ferrite core around them mains input. It is the cream coloured blob. This adds little to the amp itself although it will filter some of the high frequencies present on the mains. However its main purpose is to stop interference being injected back into the mains. You can also see the speaker cable attached to the upper left hand rail. The supplied cable was too short to reach the speakons so I used a "chocolate block" to connect the speakon cables. The reason for attaching the speaker cable by cable ties is to ensure that there's no excess pull on the connector on the PCB. The cable is quite stiff and the cable tie acts as strain relief. On the right you can just see the fuse board mounted to the right hand side of the case. These protect the auxiliary supplies from the aim amps power supply from short circuits or failures of the pre amp power supplies. I just need to connect the wires to the fuses then I can test the main amp and pre amp power supplies.

[quote name='Phil Starr' timestamp='1435832015' post='2812787'] Oh, someone asked the weight of the cab. It is 14.2 kg. [/quote] That is a good weight for a cabinet. Iwill you make up the 18mm cab before you publish the cutting plans?

Yes much more than psychology. Unfortunately almost all manufacturers inflate the output specs. One well known brand has used the same power supply/amp module in a number of models and had quoted 350W 420W and 640W. On the datasheet it shows 350W at 1% distortion. 420 peak at 10% distortion and goodness knows where the 640W came from.

Well the 220 Watt Ashdown Rootmaster is an AB but the higher powered unit is Class D. Both AlexClaber and Passinwind are right. It is all about the power supply and whether the amp/power supply are designed for pro use. The ICEPower module used in the TH500 is really designed for home hifi/home cinema use and is not really suited for use as a bass amp. The one used by Pasdinwind in his latest modular amp is a whole different beast, That said a lot of people love the TH500 so what do I know. A lot of class A/B amps and Class D use chip amps designed for the consumer market and suffer from marketing hype. Power output quoted at 10% distortion, A good Class D or Class AB or Class G or H will sound good if the content is good. And remember that most valve amps of any power is Class AB although it is usually called push pull. Now I am fascinated by Barefaced brining pit an amp. Do you have any more info Alex?

Hopefully I can post some more pics later asI have completed the mains and speaker wiring. One of the many things I have had confirmed since starting this project is that an Amos quoted power has little to do with its real world output. I don't know about valve amps, but ever snce the first solid state amp, the output powers have been quoted into 4 ohms when most speakers are 8 ohms as standard. So if we look at my old BLX130 Trace combo, it was 80 watts into the internal 8 ohm speaker, reaching its quoted 130 watts only when an extension cab of 8 ohms was connected, most combos with a speaker out are the same although some disconnect the internal speaker when the external can is connected. One point worth making here is that you should never plug or unplug s speaker when the amp is switched on. So my amp module on this build is the BoYoHo My1-251 rated at 260eatts into 8 ohms and 500 watts into 4 ohms. Sounds great but there is a caveat. This rating assumes music inputs where the average power is 1/8 the peak power. BoHoYo are not alone. ICEPower also use the 1/8 figure. The 250ASX2 is used in the Tonehammer 500 but without thermal help only outputs about 60 watts continuos. Aguilar uses two fans to cool the 250ASX2 but no extra heatsink. While this approach works, relying totally on two fans will eventually fail. As fans age they shift less and less air and will eventually not be able to keep the amp cool and the amp will shut down. A heatsink is as efficient at year 25 as it was on the day it was installed. So to enable the amp to be used at higher average powers we need to cool the amp and that either means fans or bigger heatsinks or both, I try to avoid using fans as they are often they are less reliable component and can be noisy. That is why I added the extra heatsink to my build.

Oh well one good myth destroyed by another. I must have just been lucky. Of course I have been making cabinets since 1970 but maybe my 5 builds does not give a representative sample coated to Alex's experience. Two more questions then. Is there such a think as void free ply. I mean can you order bios free or do you just have to purchase and hope. Secondly what is a void? I can only imagine knit holes or possibly where two sheets of veneer have not been lined up properly before the adhesive sets.

[quote name='stevie' timestamp='1435671339' post='2811226'] . I've no personal experience but I've heard that the Chinese stuff is to be avoided as it delaminates and is full of voids. [/quote] Below is my original post but Alwx's subsequent post suggest I am wrong. I will leave it unaltered so the next post makes sense! I am not sure of the quality of Chinese ply but the point about voids is an urban myth. When ply is made, adhesive is used to glue the layers together but it is kept under enormous pressure until the adhesive is set, the excess adhesive is squeezed to wards the edge but any knot holes or gaps are filled by the adhesive, The only voids you may find is a knot hole on the outer surfaces. However you can specify really nice looking wood for the front and back of the boards but the better stuff is exoensive.

Passinwind talks a lot of sense Stevie and when I said DIY was not the cheap option. What I really meant was that if you are looking for the lowest cost, DIY is not the way to go although this project does seem to disprove that. As for woodworking skills, fair point. Mine are reasonable although there is no sense in making the big cuts yourself.

Phil my originalm idea was to use a slot port but I have changed my mind. Why make more work for yourself, We now know the design works so why not stick with the 12mm ply and the round ports.

Phil, you have no need to apologise. Life gets in the way sometimes and you are offering your collective expertise free to the community, Having started on an amp build I have had the same problems and it always takes longer than you think to get it right. However it is no cheaper to build your own amp but it is possible to get a self build speaker at close to half the price of a commercial offering. Arguably time better spent than my amp build.

[quote name='Guinness21' timestamp='1434702592' post='2801927'] This is BASSCHAT, we don't want your guitar-playing kind around here - leave this place and never return! [/quote]I have seen the light but you know I used to use a dummy till I was two and I not ashamed of that either (mind you I still have an acoustic guitar and I am taking the 5th on the dummy)