That helps. The driver is nominally 8 ohms and supposedly 87 dB. sensitive. Applying Joppa's Rule yields a 32 WPC requirement. You should be OK with either EL34 or 7591 O/P tubes.
Search the archives for posts where I and other members discuss the 7591 based "El Cheapo Grande". IMO, it's a "perfect" mate for a limited budget and the volume control you need, after returning the borrowed preamp, is part of the setup.
If you want flexibility in using both your SS power amp and a tube power amp, things will be a little more complicated/expensive. TANSTAAFL! BTW, what drive signal level is needed to obtain full power from the SS amp?
Search the archives for posts where I and other members discuss the 7591 based "El Cheapo Grande". IMO, it's a "perfect" mate for a limited budget and the volume control you need, after returning the borrowed preamp, is part of the setup.
If you want flexibility in using both your SS power amp and a tube power amp, things will be a little more complicated/expensive. TANSTAAFL! BTW, what drive signal level is needed to obtain full power from the SS amp?
This amplifer is not a very sensible design.
I like the boards that Super8 audio makes as they are high quality boards but the Jadis circuit is silly..At the very least,the 12AX7 should be handling the voltage amplifier duties and the 12AU7 should be the driver especially since you are driving an Ultra Linear circuit. if this was pure pentode,you could get away with it but not with UL.
I like the boards that Super8 audio makes as they are high quality boards but the Jadis circuit is silly..At the very least,the 12AX7 should be handling the voltage amplifier duties and the 12AU7 should be the driver especially since you are driving an Ultra Linear circuit. if this was pure pentode,you could get away with it but not with UL.
That sounds awesome! I am not that limited, but i can get all parts except the tubes for free, so it gives me some space to do what i want to do. I just want to keep it as lean as possible, so a PCB is a must as i do not want to get into the process of making a ratsnest with wires. The range i want to work in is ~400$, which should give me enough space for tubes and trafos and a home-made chassis. I do not intend to use my Class-D amplifier, i really just want to output some power from the tube amp and use that in an isolated setup from a DAC or direct line input.
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Thats probably what gives the result of "snake oil". I'd really love to minimize the effort and maximize the output.. 🙂)
I have to be honest and say that i fell in love with the price and quality of the PCB (even though its just a picture on the big web). But now i see the issue.
Even with my limited experience with tube amps i can see this is not a good design. There are many designs that are way better and free to check. Even with extensive description how and why like those on the Lundahl site and others. Better build those in stead of this bad design.
Indeed. Those are designed by experienced people, wel tested and work. You can use other transfo's than the expensive lundahls mentioned, as long as they have the right specs.
Interesting! I am really really really really keen on finding a system which is based on a PCB rather than wires all over the place. Is this feasible?
I also came across Jims Audio: Bare PCBs of kits items in EL34 store on eBay!
I also fell across this baby which in contrast is a KT88: http://www.ebay.com/itm/2X-DIY-PCB-...r-amp-board-/161606386411?hash=item25a07dc2eb
More snake oil? 🙂)
I also fell across this baby which in contrast is a KT88: http://www.ebay.com/itm/2X-DIY-PCB-...r-amp-board-/161606386411?hash=item25a07dc2eb
More snake oil? 🙂)
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If you can spend more, you can also look at oddwatt designs sets. He makes them for 110 and 220v mains and they are high quality designs with parts included. But it's much more expensive and they need to be shipped from the US (wich is reasonable priced in his case).
Rob,
A word to the wise, Octal sockets on PCBs frequently lead to trouble. Chassis mount Octal tube sockets and use either turret boards or PCBs for the remainder. Noval (9 pin mini) sockets are OK on the substrates used for PCBs and turret boards. It's a question of the amount of force applied, when tubes are inserted into their sockets. A PCB may be convenient, at construction time. However, if the PCB's substrate cracks, when 1 or more tubes are swapped, repairing the damage will very difficult, if not "impossible".
Point to point (P2P) wiring should not be a "rat's nest". All sorts of photos of neat, well organized, P2P wiring are available.
If you are adamant about a "100%" PCB project, you'll need to design your own board(s) for push-pull/parallel (PPP) circuitry using 4X EL84/6BQ5s per channel. 4X EL84s use the same O/P "iron" and deliver the same power as 2X EL34s, but some circuit complexity is needed to avoid, among other things, "current hogging".
Compromises are always present.
You will have to decide where they will be in your projects.
A word to the wise, Octal sockets on PCBs frequently lead to trouble. Chassis mount Octal tube sockets and use either turret boards or PCBs for the remainder. Noval (9 pin mini) sockets are OK on the substrates used for PCBs and turret boards. It's a question of the amount of force applied, when tubes are inserted into their sockets. A PCB may be convenient, at construction time. However, if the PCB's substrate cracks, when 1 or more tubes are swapped, repairing the damage will very difficult, if not "impossible".
Point to point (P2P) wiring should not be a "rat's nest". All sorts of photos of neat, well organized, P2P wiring are available.
If you are adamant about a "100%" PCB project, you'll need to design your own board(s) for push-pull/parallel (PPP) circuitry using 4X EL84/6BQ5s per channel. 4X EL84s use the same O/P "iron" and deliver the same power as 2X EL34s, but some circuit complexity is needed to avoid, among other things, "current hogging".
Compromises are always present.
You will have to decide where they will be in your projects.
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Rob,
A word to the wise, Octal sockets on PCBs frequently lead to trouble. Chassis mount Octal tube sockets and use either turret boards or PCBs for the remainder. Noval (9 pin mini) sockets are OK on the substrates used for PCBs and turret boards. It's a question of the amount of force applied, when tubes are inserted into their sockets. A PCB may be convenient, at construction time. However, if the PCB's substrate cracks, when 1 or more tubes are swapped, repairing the damage will very difficult, if not "impossible".
Point to point (P2P) wiring should not be a "rat's nest". All sorts of photos of neat, well organized, P2P wiring are available.
If you are adamant about a "100%" PCB project, you'll need to design your own board(s) for push-pull/parallel (PPP) circuitry using 4X EL84/6BQ5s per channel. 4X EL84s use the same O/P "iron" and deliver the same power as 2X EL34s, but some circuit complexity is needed to avoid, among other things, "current hogging".
Compromises are always present.
You have a good point with the heat and force, i cannot take that away from you! Maybe i can make a slight compromise with partial PCB mount like Oddblock builds. I am not trying to be a "wire nazi" ;-)
My biggest concern right now is that there are so many do's and dont's that i find it hard to differentiate.
Oddwatt makes diy kits you need to assemble yourself. You can find a lot of his schemes online if you want to do a full diy project. But if you want a pcb, you need to buy his (good) kits.
Rob,
You are clearly budget driven. Use your ingenuity and build an "El Cheapo Grande". A 2 stage amp, with volume controls built in, caters to budget conscious folks. Work around the absence of a pre-manufactured PCB by using perf board and/or something like this. Chassis mount the 7591 "finals", for reasons previously discussed.
A thick walled, commercial kitchen, aluminum baking pan makes a sturdy, cost effective, chassis.
To keep your cash outflow down, you must provide lots of "sweat equity".
You are clearly budget driven. Use your ingenuity and build an "El Cheapo Grande". A 2 stage amp, with volume controls built in, caters to budget conscious folks. Work around the absence of a pre-manufactured PCB by using perf board and/or something like this. Chassis mount the 7591 "finals", for reasons previously discussed.
A thick walled, commercial kitchen, aluminum baking pan makes a sturdy, cost effective, chassis.
To keep your cash outflow down, you must provide lots of "sweat equity".
Thanks for your advice! I am really detemined to do that.. The terminal boards look quite nice. I will look into El Cheapo Grande. Is there a specific thread i should look into?