JapanAxe Posted January 7, 2021 Author Share Posted January 7, 2021 7 hours ago, slojo said: Have you seen these kits, I think they look very cool? I could be very tempted to build one. https://www.trinityamps.com/product/trinity-trip-top-kit/ Yes I have. I plan to build mine from scratch though! 1 Quote Link to comment Share on other sites More sharing options...
slojo Posted January 7, 2021 Share Posted January 7, 2021 1 hour ago, JapanAxe said: Yes I have. I plan to build mine from scratch though! Good for you 👍 Quote Link to comment Share on other sites More sharing options...
BassmanPaul Posted January 9, 2021 Share Posted January 9, 2021 (edited) On 07/01/2021 at 16:19, JapanAxe said: Yes I have. I plan to build mine from scratch though! There are some helpful hints you can get to aid in the build so don't be afraid to ask. Good luck - you may well need it. I built my first amp, for a record player, when I was about twelve. It did work too!. Edited January 9, 2021 by BassmanPaul Quote Link to comment Share on other sites More sharing options...
Chimike Posted January 24, 2021 Share Posted January 24, 2021 Well, Just finished populating my turret board, and starting to solder. , However , don't underestimate how long it takes to gather all the various bits you'll need , and the cost. Def makes that trip top look like a good deal ! 2 Quote Link to comment Share on other sites More sharing options...
Quilly Posted February 27 Share Posted February 27 I know this is an old thread , but I just built a tweed 5e3 amp and Im jurs itching to put together a bass amp, I just can’t see that many bass kits out there apart from modulous. How did your amp turn out ? Quote Link to comment Share on other sites More sharing options...
Bassybert Posted February 27 Share Posted February 27 (edited) I think Ceriatone do a B15 style kit, by all accounts their kits are great quality. https://ceriatone.com/aunt_peg/ I built a 5e3 Tweed Deluxe about 20 years ago and love it. Built the cabinet from scratch with finger joints and everything. Edited February 27 by Bassybert 1 Quote Link to comment Share on other sites More sharing options...
JapanAxe Posted February 27 Author Share Posted February 27 8 minutes ago, Quilly said: I know this is an old thread , but I just built a tweed 5e3 amp and Im jurs itching to put together a bass amp, I just can’t see that many bass kits out there apart from modulous. How did your amp turn out ? Very well thanks, I was just playing through it this evening. The build thread is here. And yes amp building is addictive - I think I’ve built 7 since my first Modulus 5E3 kit. Unfortunately valve amp kits for bass seem to be few and far between. I also built (not from a kit but from design I found online) a bass head based on a Marshall JTM45 but I’m not so happy with that one - think I’m going to turn it into the guitar version! Quote Link to comment Share on other sites More sharing options...
JapanAxe Posted February 27 Author Share Posted February 27 Just now, Bassybert said: I think Ceriatone do a B15 style kit, by all accounts their kits are great quality. I built a 5e3 Tweed Deluxe about 20 years ago and love it. Built the cabinet from scratch with finger joints and everything. Yes I based my layout on the Ceriatone but just went for cathode biasing rather than having grid biasing as a switchable option. 1 Quote Link to comment Share on other sites More sharing options...
Quilly Posted February 27 Share Posted February 27 8 minutes ago, JapanAxe said: Very well thanks, I was just playing through it this evening. The build thread is here. And yes amp building is addictive - I think I’ve built 7 since my first Modulus 5E3 kit. Unfortunately valve amp kits for bass seem to be few and far between. I also built (not from a kit but from design I found online) a bass head based on a Marshall JTM45 but I’m not so happy with that one - think I’m going to turn it into the guitar version! I’d like to put together a 100w plexi style bass amp with 4x EL34s I can’t imagine that’s too complicated? It’s the cost of the actual cabinets I find a bit ludicrous. Almost the same cost of all the innards ….for a wooden box essentially Quote Link to comment Share on other sites More sharing options...
JapanAxe Posted February 28 Author Share Posted February 28 12 hours ago, Quilly said: I’d like to put together a 100w plexi style bass amp with 4x EL34s I can’t imagine that’s too complicated? It’s the cost of the actual cabinets I find a bit ludicrous. Almost the same cost of all the innards ….for a wooden box essentially Yes the enclosure/cabinet is always the challenge for me. Where possible I try to re-purpose these from dead (or at least undesirable!) solid state amps. Also I’m useless at woodwork! Quote Link to comment Share on other sites More sharing options...
BassmanPaul Posted February 28 Share Posted February 28 I have built hundreds of amps over the last sixty years. The Ampeg B15 is a very simple build. You should stick to the circuit exactly and use the 6SL7 octal preamp tubes. They have a certain 'something' that adds to the B15 mystic. I have every thing I need including chassis to build six more amps. As winter progresses I'll make a start on the first. I'm thinking of a B15 clone using a pair of KT66s that I've had in my tube stores for years. Time to put them to good use. I already own a B15NF and whilst reconditioning it I ran into Two problems. After installing new caps I experience flash over in the GZ34/5AR4 rectifier. the cure was to add a fast recovery silicon diode in series with each plate/anode of the GZ34. The second was the 6L6GCs red plating in spite of the negative bias being correct. Cure was replacing the 270KΩ grid bias resistors with 100KΩ as per the RCA tube manual. I feel that the amp is sensitive to the 'new' tubes being produced today. Good luck with the build. It's very rewarding when you step out on stage using equipment that you put together with your own hand!! 1 Quote Link to comment Share on other sites More sharing options...
Baloney Balderdash Posted February 29 Share Posted February 29 I once owned the 1968 version of the 60W B-15S, with solid state rectifier, I believe. Really regret being stupid enough to sell it, it sounded absolutely amazing. Maybe worth considering for the extra wattage. Quote Link to comment Share on other sites More sharing options...
BassmanPaul Posted February 29 Share Posted February 29 (edited) For some reason I have yet to measure the output capabilities of my B15 unit. From the diagram and voltages present it should give at least 45 odd Watts. BTW @JapanAxe the correct term is Fixed Bias and not grid bias. Edited February 29 by BassmanPaul Quote Link to comment Share on other sites More sharing options...
JapanAxe Posted February 29 Author Share Posted February 29 58 minutes ago, BassmanPaul said: For some reason I have yet to measure the output capabilities of my B15 unit. From the diagram and voltages present it should give at least 45 odd Watts. BTW @JapanAxe the correct term is Fixed Bias and not grid bias. Fixed bias is the more common term but grid bias is also used as for example here. ‘Fixed bias’ seems to confuse people because it is often variable by means of a pot! Quote Link to comment Share on other sites More sharing options...
BassmanPaul Posted February 29 Share Posted February 29 (edited) Doesn't confuse me one bit! Even though it can be variable to ensure correct bias level at set up, once set it doesn't vary so is fixed. Virtually everyone in the amplifier field refers to the arrangement as Fixed Bias. Just noticed you're from Swindon. My Dad's family hailed from Swindon. Edited February 29 by BassmanPaul Quote Link to comment Share on other sites More sharing options...
Beer of the Bass Posted February 29 Share Posted February 29 It always bothers me that there's a modelling amp company called Positive Grid, when usually the grid being positive means something is about to be on fire! Quote Link to comment Share on other sites More sharing options...
agedhorse Posted March 1 Share Posted March 1 (edited) 3 hours ago, Beer of the Bass said: It always bothers me that there's a modelling amp company called Positive Grid, when usually the grid being positive means something is about to be on fire! Not in the preamp world, the grid is often slightly positive relative to ground. It also depends on the circuit itself, for example, cathode followers have positive grids. Edited March 1 by agedhorse 2 Quote Link to comment Share on other sites More sharing options...
BassmanPaul Posted March 1 Share Posted March 1 (edited) Take single triode section from a 12AX7, cathode is grounded, grid to ground via a very high value resistor. Signal connects through an isolating capacitor. This is a positive bias stage. Looking through schematics you can see this used time and time again. Back in the day tube tape recorders used the scheme to match the high impedance of Chrystal microphones Edited March 1 by BassmanPaul Quote Link to comment Share on other sites More sharing options...
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