Chienmortbb

Firstly a warning: There are dangers in opening or building amplifiers. Unless they are battery powered, somewhere inside there are mains voltages that can KILL. Depending on your location these could be between 100V ac and 230V ac nominal. Only open an amplifier if you really know what you are doing. I worked in Electronics until my retirement and was an IEng (Incorporated Engineer) Electronics, having studied to degree level. Despite that, I do not know everything and have had to cram up on current safety requirements in order to make this amplifier safe. I have used commercial power modules form ICEPower that are built, and certified, to current standards around the world. DO NOT try to build amplifiers with low cost power supplies and/or amplifiers purchased from EBAY, Ali-Express, Bangood etc. Remember that you are connected to your amp when playing, don't save pennies, save your life. Now on to the build. The Trigger's Broom of Amps? I have one of the original carpet covered After Eight combos. It is rated at 15W and has an 8" Sica 35 watt speaker that is showing signs of wear. The amp makes a strange noise after a deep notet is allowed to sustain. It is hard to fault find and I have decided to rip out the guts and rebuild it. This project is related to my other project to turn the Basschat BC112 into an active FRFR cabinet and much of this design will be used (or possibly discarded) for that design. The existing unit is from the series that included the Perfect Ten and Five Fifteen and appears to have been codenamed the BakPac series. Eight Ten and Fifteen tells us the size of the speaker and the amp can have extra components added to increase the power output for the Ten and Fifteen inch variants. The powers abvailable from the amp is 15 watts, 30 watts and 65 watts respectively. The controls are shown below including the new handle that I had already replaced. You can just make out the outline of the old handle in the picture.

I have had to modify this project due to ........ guess what? So I am prototyping some of the bits, in a lockdown build renovating an Ashdown After Eight. I will post it in the builds area and post a link here as soon as I can. TheBasschat 1x12 Active FRFR Cabinet is still alive and will be completed after we get out of lockdown.

To break mine I need I usually put 20 Hz through them overnight. The advantage of 20Hz is that you cannot hear it but can see the cone moving.

I seem to remember that many of the early Jazz basses were made with stacked knobs like that.

Good call, also while the amp is out clean any dust, fluff or dirt from the heat sink as any of these will either reduce/disturb the airflow or reduce the heat transfer.

check that there are no air leaks in the cab. I had a cab that made a similar noise and it was air leaking out through the jack socket.

If you are going to put an HPF in thhe system, the best -3dB point depends on the cabinet response and it need to be quite vicious (24dB/Octave) to protect the drivers and take out the low end waffle.

Very wise. The team at Ashdown know their stuff and would have considered this in the design. I am just repairing my 15 year old After Eight combo and the thing that impressed me was how well the cooling has been thought out. No fans but a really well thought out design where the heatsink is bolted to the rear of the chassis. It not only has cooling vents, but the chassis is mounted on two spacers so that air can flow behind the chassis. There is also thermal compound between the heat sink and the chassis to improve heatflow between the two.

You need to look at the amp as it may be that one fan blows inwards, the other blows outwards. It depends on where they are placed.

If you look at the fans they will have an arrow on the top usually pointing to the direction of airflow.

Just a couple of points. Firstrly Channel 38 is a great call, but do pay your licence fee. Incidently, there are no plans yet but Channel 38 is earmarked for other use in the future. Just a bit of backgroud on 5GHz. That band was given to the Wireless Mic manufacturers for the development of Wireless mics shortly before Channel 69 was stolen. Sadly, in the early days of digital mics, few saw the benefit and so the band was unused. As a result a substatial part of it was given over to WiFi.

Bill is right the Delta/Alpha/Beta 10s are less than ideal for bass and unlikely to improve on the stock drivers. Remember the cabinet was tuned to get the best out of the drivers it was supplied with subject to the contraints of cost/the marketing department etc. As for the original Blue Line driver, it could well be a SICA but probably made in the far east under licence in the same way that Eminence do. The real clue is in the lettering on the back of the driver. The contries thta use the graphical writing style tend to favour serifed fonts whearas Western countries favour non -serifed characters. My advice is to put the original drivers back in.

Generally Aluminium tape is thicker and that negates the improved conductivity. However I agree that copper is better. Neither is any used for magnetic shielding but as most of the noise we get now is RF pulses from various appliances, that does not matter.

Sorry to ressurect a zombie thread but it is probably quite usual as the TRL072 IC used in the amp is a bit noisy. REpolacing it with a real audio opampo like OPA2134 will probably remove most of the hiss. I am reapiting mine at the moment so will pots here when I have done it and chnaged the Tl072 for an OPA2134.

It takes more work but aluminium tape is the best shielding. Th issue is that you cannot solder it ans there is none that I know of that has conductive adhesive.

Humbuckers reduce the i nduced mains hum. It is 60Hz in the USA, Canada, Japan but 50Hz in Europe. However you are correct ijn that most of the interference is EMI/RFI.

In the diary.

I am sure this is the right decision . I would have had to give it a miss being in the at risk group. Look forward to it later in the year.

I looked at those square handles but was not sure how well they were sealed. Presumably they are fine?

My sources say two things, If I, a chronic asthmatic that has had several bouts of pneumonia ( so callde co-morbidities) were in need of a respirator as was an otherwise fit 22 yera old and only one was available, guess who would not get it... moi. Secondly, all the advice was given because there are no powers to make us do something. That can (and will) change as an emergency bill passes. I predict it will be in place by next weekend.

I do agree about the mics Phil. I missed the fact that the singer was using a cheap Shure. That may be the best and cheapest upgarde initially I am now using the Solo from Sontronics. It is cheaper than the SM58 and made in Dorset. AKG and Sennheisers are also worth looking at. In fact I try to avoid the SM58 as it is OK, but IMHO is a very old design that is bettered by many less expensive mics these days.

My heart says go ahead but as someone in the "at risk" group, I would have to decline anyway.

I agree and the reason I suggested the Alto subs is that they have the DSP settings to match the Tops.

Sorry I was caught out by Alto’s numbering system. It is Tx212S. As you can see from the picture, it has a DSP setting for the 212 tops. https://www.gear4music.com/PA-DJ-and-Lighting/Alto-TX212S-Active-Subwoofer/34ZN