That just sounds like simple clipping to me. Don't forget, the stock DCPP only has approx. 20 watts/ch. With average efficiency speakers, it's not that hard to push the amp beyond it's happy place.
jeff
That just sounds like simple clipping to me. Don't forget, the stock DCPP only has approx. 20 watts/ch. With average efficiency speakers, it's not that hard to push the amp beyond it's happy place.
jeff
Yea, I suppose that's it. I hadn't really experienced that quite so dramatically before but then I don't often listen to tracks with that much low bass so hot in the mix. I wasn't listening that loud. I guess I should be getting a little more than 20wpc using 6.6K iron (but not enough to make a significant difference).
Anyway, still pleased as punch
Yea, I suppose that's it. I hadn't really experienced that quite so dramatically before but then I don't often listen to tracks with that much low bass so hot in the mix. I wasn't listening that loud. I guess I should be getting a little more than 20wpc using 6.6K iron (but not enough to make a significant difference).
Anyway, still pleased as punch
Your DCPP is in better shape than mine. After all that hot-rodding at 80+WPC it went back into a box and has been sitting there since.
I haven't been on the forum as much lately, so I am not up to speed on your build. What OPTs are you using? I wonder if you opted to connect the GFB or not? Maybe it would help some if your speakers are difficult to drive at those frequencies.
I'm using a total of 570u in the B+ at 460V. I have an excellent sustained low end capability with 6GV5 tubes in one amp and 6LB6 tubes in the other. I'm also using 6.6KRa hammonds, a set of 40 watt and a set of 60 watt in the larger amp. The 6.6 K iron runs longer in class A power than 4.3k iron and sounds sweeter with less feedback.
GFB is hooked up. My iron is 6.6K from a Knight kit using a Mullard 5-20 circuit. At one point I think I figured out that they were made by either Central Transformer Company or Quality Transformers & Coil Co. (both Chicago companies).
It just occurred to me that before I get everything settled and buttoned up I could try out a different set of iron with it just to see how they sound. I've got some iron from an HK amp that used 7355. Supposed to be pretty good stuff. Primaries are around 4.3K. Hmmm. Maybe...
It just occurred to me that before I get everything settled and buttoned up I could try out a different set of iron with it just to see how they sound. I've got some iron from an HK amp that used 7355. Supposed to be pretty good stuff. Primaries are around 4.3K. Hmmm. Maybe...
A quick question for the really smart people -
My C30 (in the B+ regulator circuit) appears to be bad. It is a 10uF 450V.
Can I replace it with a 22uF 450V? I have a few on hand, or should I wait and order the 10uF? I'm not entirely clear on what that capacitor does, and don't want to mess anything up.
(image from P.Millett website)
My C30 (in the B+ regulator circuit) appears to be bad. It is a 10uF 450V.
Can I replace it with a 22uF 450V? I have a few on hand, or should I wait and order the 10uF? I'm not entirely clear on what that capacitor does, and don't want to mess anything up.
(image from P.Millett website)
Did anyone (read. George) ever try 6AV5GA in this circuit? I´m asking because i have ten or eleven NOS specimens from Sylvania plus two large homemade output transformers (5,8k p-p with 150VA cores) and a 310V 400mA + 6,3v 8A toroid on my shelves.
The idea is to replace the class AB mosfet amp (built on cheap modules from Ebay) that drives my 2x18" OB subs. (The mosfet amps was supposed to be a dual mono design but I dropped one of the toroids on a sharp edge during the assembly, resulting in a vastly underspeced PSU... )
Not that the Fets are doing anything wrong soundwise, I just can stand having cheap class AB SS gear in my main rig.
I´m expecting at least 40W from a pair of 6AV5GA at 420V and 5,8k p-p, less than half of what I get from the fets but it should be sufficient. Everything above 150Hz is horn loaded and can deliver mad SPL´s from a few watts.
The OPTs must be put through some torture tests before I build anything with them. They are wound on a DIY CNC winding machine that ensures the correct number of turns in every layer but the whole process was still a bloody mess.
The idea is to replace the class AB mosfet amp (built on cheap modules from Ebay) that drives my 2x18" OB subs. (The mosfet amps was supposed to be a dual mono design but I dropped one of the toroids on a sharp edge during the assembly, resulting in a vastly underspeced PSU...
)Not that the Fets are doing anything wrong soundwise, I just can stand having cheap class AB SS gear in my main rig.
I´m expecting at least 40W from a pair of 6AV5GA at 420V and 5,8k p-p, less than half of what I get from the fets but it should be sufficient. Everything above 150Hz is horn loaded and can deliver mad SPL´s from a few watts.
The OPTs must be put through some torture tests before I build anything with them. They are wound on a DIY CNC winding machine that ensures the correct number of turns in every layer but the whole process was still a bloody mess.
I did not try the 6AV5 in the red board. The 6AV5 is quite similar to the 6GV5 which was one of the tubes actually specified for use in the board. I tried dozens of sweep tubes in Pete's board and every true horizontal (line) sweep tube that I tried worked fine. I didn't actually try the 6AV5 since I was already convinced that I knew how it would work based on several similar sized sweep tubes. Some vertical (frame) sweep tubes require an external supply for G2 since most of them run the screen in the 300 to 400 volt range and Pete's board won't go there easilly.
All the tubes of similar size to the 6AV5 can make about 80 watts, but more than 420 volts are required. I'm not exactly sure what you will get with 420 volts and 5.8K, but 40+ watts should be easy. The 6AV5 type tubes can work down to 3300 ohms.
George: Thanks for replying. I could use different power transformers (industrial transformers in a back to back configuration) and get ~500Vdc, but I´m not sure how much voltage my output transformers can handle. Alternative power tubes are 25E5 (PL36) or 40KG6 (PL519), the former feels a bit too small and the latter too big. I´m on a tight budget here so I have to work with what I have, even though I´m tempted to buy a bunch of Sylvania 12DQ6B for six buck a piece from a local seller.
Connecting the OPT´s as 2,9k/4-8 ohms might be an option too.
Connecting the OPT´s as 2,9k/4-8 ohms might be an option too.
Hi everyone,
I am in the process of building this amp. My experience is limited; I only built Mr. Millett's Jonokuchi amp before, albeit with much ease. I want to include a potentiometer to my build to be able to adjust volume in this amp. I have an Alps RK27 100 ohms. It has 6 pins (3 pins 2 rows). I will mount the pot on the chassis. Can somebody explain me on how to wire it to the circuit (PCB). I am an Aero eng, so I am good with building stuff and soldering but have very limited electronics knowledge. So please be simple.
Thanks.
Emre
I am in the process of building this amp. My experience is limited; I only built Mr. Millett's Jonokuchi amp before, albeit with much ease. I want to include a potentiometer to my build to be able to adjust volume in this amp. I have an Alps RK27 100 ohms. It has 6 pins (3 pins 2 rows). I will mount the pot on the chassis. Can somebody explain me on how to wire it to the circuit (PCB). I am an Aero eng, so I am good with building stuff and soldering but have very limited electronics knowledge. So please be simple.
Thanks.
Emre
Have a look here:
controls_pot_alps
Basically the pot is connected between the input RCA jacks ("input" on the drawing), and the input to the PCB ("output" on the drawing).
Pete
In the drawing, each section (1 and 2) has an input, output and ground. You can arbitrarily use section 1 as left, and 2 as right, or vice-versa.
I would wire the RCA from one channel to "IN" and "GND" of one section of the pot with a pair of twisted wires. Then from "OUT" and "GND" to the PCB input and ground terminals with another pair of wires. Then do the same thing for the other channel.
So each section's "GND" has both a wire to the RCA, and to the PCB.
Pete
I would wire the RCA from one channel to "IN" and "GND" of one section of the pot with a pair of twisted wires. Then from "OUT" and "GND" to the PCB input and ground terminals with another pair of wires. Then do the same thing for the other channel.
So each section's "GND" has both a wire to the RCA, and to the PCB.
Pete