Hello everyone,
I am a noob looking to do a scratch build of this circuit and had some questions and was looking for input.
1. If I wanted to use a grounded bus wire for the pots (instead of grounding to the pots themselves), is this possible?
[url]http://www.gad.net/Blog/wp-content/uploads/2011/06/1963-Bassman-6G6B-Layout.jpg/url]
The normal channel pots could all be grounded to the chassis grounding point off board to the right of red/yellow wires and bass channel to similar grounding point off board to right of black (OT I think) wire.
2. If I use a 10K linear bias pot, what would be a good value for the resistor, many used the AA864 value, I dunno.
3. Is the RG 174 shielded wire that beneficial for input jacks (hum)? Any other recommended areas that it's beneficial?
4. If I use 6L6GC Winged C instead of 5881, will I need to do any adjustments in terms of parts, wiring, etc?
5. This might spark some debate because it's solely opinion. The OT. Im looking at Classictone and the much more expensive MM. Dunno what to do here and was curious to hear what others have to say. Please don't respond to other's comments in regards to this that it gets lost.
Any input is valued--TIA. I sincerely appreciate it.
1, yes you can use a ground buss. Careful not to make loop.
2, Good place to start, but with fixed adjustable but you may have to try a couple of different resistor values. If a scratch build, I usually use a 25k or even 50k bias pots. Easier to get adjustment parameters.
3, Not in the stock circuit. Should be able to build it quiet without any shielded cable. Not saying it will not, but I have old amps without shielded cable ant the are quiet and do not play radio.
4, No adjustment necessary, may bias differently from tube to tube, but they all do anyway.
5, Mercury OT's are great, but the original did not have a designer OT. You can tell a difference. I have an original 62 and the OT is 4 ohm. I would like a multi-tap OT for it so I could use more cabinets. If I were building a scratch, I would use a Heybour. Great stuff and less money than Mercury. Never used a Classictone OT, but I have been tempted. I have used many of their PT's and they are good.
6, 1 watt is fine, but I always overbuild and do not use Carbon comp resistors. They add that vintage noise and they drift all over the place. I use 1 watt Dale resistors except for the dropping resistors, there I use 3 watt Ohmite wirewounds. Reason, is they are quiet, last a long time and when I complete a clone amp I do not dwiddle with it much. With clone amps I use them for a while, but usually end up selling them to build something else. I don't want to have to restore it before I sell it.
If you know you want that tone and plan on using it for years, go with the best parts you can get. CTS pots, Sozo blue caps and F&T filter caps. Teflon jacket wire. Push back is easy to use, but a little messy. It may cost a couple hundred dollars to use better parts, but you are doing a scratch so I know you are not trying to save money.
Also, I have used many different tubes in my original. The Tung-sol USA NOS are not that expensive and are remarkable sounding in this circuit. They have a nicer transition to breakup and will do it earlier. They will even react better to string attack. On mine you can have the volume under halfway and dig the strings and get a great snappy breakup especially on double stops.
I really love this circuit and if I sold mine, I would build one immediately and since it's value would not be hurt, I would install a passive loop just for modulation effects and a LarMar master volume and probably a fender reverb circuit however I have recently tried a SS reverb unit and it sounds better when using overdrive. The Fuchs Overdrive Special uses one (where I got the idea) and it is really nice as it adds no noise, I looked everywhere for the tank and finally we opened it up. I could not tell it did not have a large tank.
Great amp, keep us posted on your decisions and progress.
Topic: 6G6B Bassman Scratch Build Questions (Read 3209 times)