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Started by smsuryan, December 02, 2023, 09:46:59 PM
Quote from: phatt on December 03, 2023, 05:31:48 PMCan I suggest you mention the model and maybe a link to Schematic might help.If you have the Amp open, take some gut shot pics of the internals would be helpful.Phil.
Quote from: Tassieviking on December 03, 2023, 10:17:37 PMI was looking at the schematics as well and we really need to know what model we are talking about, there are differences between the different size amps.We might also need help identifying some of the components as they might not be marked the schematic.I was pleasantly surprised when I found the schematics on Carvins website.https://carvinaudio.com/pages/guitar-amp-schematics
Quote from: Tassieviking on December 03, 2023, 10:17:37 PMhttps://carvinaudio.com/pages/guitar-amp-schematics
Quote from: smsuryan on December 03, 2023, 08:50:50 PMnot sure how to distinguish where the "blues button" is located and omit the clean channel.
Quote from: g1 on December 04, 2023, 12:32:28 PMQuote from: Tassieviking on December 03, 2023, 10:17:37 PMhttps://carvinaudio.com/pages/guitar-amp-schematicsExcellent. From the SX package on that page, the SX50 is pg.14 and 15 of the pdf.Quote from: smsuryan on December 03, 2023, 08:50:50 PMnot sure how to distinguish where the "blues button" is located and omit the clean channel. The blues button puts back the 500Hz that is notched out for metal and hard rock tones. It is only on ch.1. It is shown as S1A and S1B around IC's A3A and A8A.Around Vol.3 pot (which should be labelled Vol.2?) you can see the 500HZ notch circuit with no defeat switch.
Quote from: Tassieviking on December 05, 2023, 06:57:33 AMDo you have a SX-50 still ?I am wondering as we will have to identify some transistors (FET's) as they don't seem to be marked on the schematic.Q21 and Q22 are most likely JFET's in a TO-92 casing so we need to identify them.The LED's D1, D3 and D5 are most likely red, but best to make sure, they should be on the PCB as well.
Quote from: Tassieviking on December 09, 2023, 11:48:16 AMThe SX300 preamp on page 25 in the manual has a very similar input circuit as the SX50, the SX3000 uses 2N5457 fet's so I think we can say that Q21, Q22 are 2N5457 FET'sThis might make a nice pedal from the overdrive channel, 2 FET's and 4 dual OP amps is all, 5 pots and 1 switch as well
Quote from: phatt on December 27, 2023, 06:53:24 AMQuote from: Tassieviking on December 09, 2023, 11:48:16 AMThe SX300 preamp on page 25 in the manual has a very similar input circuit as the SX50, the SX3000 uses 2N5457 fet's so I think we can say that Q21, Q22 are 2N5457 FET'sThis might make a nice pedal from the overdrive channel, 2 FET's and 4 dual OP amps is all, 5 pots and 1 switch as wellThat would be the best advice for something that would otherwise exceed the cost of trying to build a whole amp from scratch Phil.
Quote from: phatt on December 28, 2023, 07:09:46 AMI don't wish to dampen your enthusiasm but but you may eventually be defeated.There is just so many nightmares waiting for you.My advice would be to go buy a bread board and parts needed to run a 30 volt split rail supply and start experimenting.You will spend many months getting the preamp to work.Then you will have to learn how to use a cad program to make the preamp PCB, another few months will go by.at that point your best bet is to purchase a poweramp kit.Meantime you will then need to consider a case to mount it all.Oh did I mention that layout of PCB can be a nightmare if you don't understand that sensitive sections will pick up hum from bad design as well you will need to learn how to NOT create ground loops a common issue when designing sensitive audio circuits.AND heaps of other gotcha's that better minds on this forum will tell you about.If it interests you,My rig consists of a pedal board, most of which is my own designs and my main amp is nothing more than an old SS Keyboard amp.I just posted an mp3 composition I wrote on here last week.It will give you some idea of what can be achieved with average gear.https://www.ssguitar.com/index.php?topic=5309.msg41595;topicseen#new.But keep in mind I've been doing this for over 30 years so I have learned a lot about how to get things to work together to get the Sound/Feel/dynamics to come together.40 odd years back I was in your situation faced with a similar dilemma so I have a fairly good idea of what is ahead for you,,So I wish you luck.Be aware DIY is rather addictive. Phil.