That result of better sound by fitting a pre-amp tells me that the source was incapable of driving the load you attached to it.
It is the Source you should be trying to sort out.
It is the Source you should be trying to sort out.
Feeding my new F4
Having just finished my F4, I've been thinking about a suitable gain stage for it, and I have built two.
The first was a simple 5534 op-amp preamp: it seemed to work fine, but I wanted to try something a bit more exotic, so I found the JFET BOZ.
A quick lash-up on a matrix board, stuck in an L-shaped support, powered by a couple of 9 volt batteries.
Sounding good.
No tuning yet: I'm planning to try 27V to see if there's much of a difference when I get a chance.
The gain stage is connected to an old First Sound passive preamp, so I have too many cables, but it seems to work. I omitted the gain control from the JFET BOZ therefore.
tim
Having just finished my F4, I've been thinking about a suitable gain stage for it, and I have built two.
The first was a simple 5534 op-amp preamp: it seemed to work fine, but I wanted to try something a bit more exotic, so I found the JFET BOZ.
A quick lash-up on a matrix board, stuck in an L-shaped support, powered by a couple of 9 volt batteries.
Sounding good.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
No tuning yet: I'm planning to try 27V to see if there's much of a difference when I get a chance.
The gain stage is connected to an old First Sound passive preamp, so I have too many cables, but it seems to work. I omitted the gain control from the JFET BOZ therefore.
tim
You can try with a distortion analyzer for get the adequate voltage supply for your jets.
I'll be at BA looking forward to learning more. Unless you'd like me to get started early...🙂
You'll be happy with BoZ. I've built four, all slightly different and a B1. I felt the B1 had a better mid-range but I needed more gain so BoZ was the answer.
I may have posted this before but here is my BoZ on a cap (BoZoaC). Shortest signal path on the planet.
I may have posted this before but here is my BoZ on a cap (BoZoaC). Shortest signal path on the planet.
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Somewhere in this thread, Mr Pass said 16v is the sweet spot. So you are close right now.
Or, you can try this suggestion.
Source resistor value change was also discussed. I think it changed from 10 to 22 Ohms, but check to be sure.
See post #691
http://www.diyaudio.com/forums/pass-labs/103050-jfet-boz-97.html#post2353349
With the gain of the original BOZJ with the 2SK170 as high as it is, and the potential for overload so high, I'm surprised no one has suggested a shunt volume control... Replacing the 25K input pot with a 20K resistor in series with a 5K pot would give a much larger useful range on the pot...
Now, where did I put those J310s...
Roscoe
Now, where did I put those J310s...
Roscoe
How do you like those J310s? I purchased a bag of them years ago and plan on using them in an upcoming project -- 300 watt class A in a choke loaded, differential follower configuration.
What'll be yummie is a 300 watt class a amp -- assuming I can pull it off. What's the worst that can happen, black out the West coast of the US?
300W Class A, that's going to take a LOT of J310s 😉
I haven't used them for audio yet, I bought a bunch for RF work, now I just need to find the darn things....
Roscoe
I tried the jboz with the 310 with bad results, more distortion and an hf oscillation (Maybe I did some things wrong)