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Old 24th August 2011, 03:54 PM   #1041
AndrewT is offline AndrewT  Scotland
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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.
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Old 12th September 2011, 01:29 AM   #1042
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Default 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.

Click the image to open in full size.

Click the image to open in full size.

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
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Old 12th September 2011, 01:49 AM   #1043
ramallo is offline ramallo  Europe
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Quote:
Originally Posted by timbarnes View Post
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.

Click the image to open in full size.

Click the image to open in full size.

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.
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Old 12th September 2011, 01:54 AM   #1044
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Next you will need to try the BA-3.

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Old 12th September 2011, 02:03 AM   #1045
ramallo is offline ramallo  Europe
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Quote:
Originally Posted by Nelson Pass View Post
Next you will need to try the BA-3.

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Old 12th September 2011, 02:36 AM   #1046
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Quote:
Originally Posted by Nelson Pass View Post
Next you will need to try the BA-3.

I'll be at BA looking forward to learning more. Unless you'd like me to get started early...
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Old 12th September 2011, 02:37 AM   #1047
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Quote:
Originally Posted by ramallo View Post
You can try with a distortion analyzer for get the adequate voltage supply for your jets.
Ain't got one. Just a multimeter. But it is sounding good.
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Old 12th September 2011, 03:08 AM   #1048
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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.
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File Type: jpg BoZoaCs.jpg (325.6 KB, 880 views)

Last edited by mhouston; 12th September 2011 at 03:21 AM.
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Old 12th September 2011, 12:55 PM   #1049
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Quote:
No tuning yet: I'm planning to try 27V to see if there's much of a difference when I get a chance.
Somewhere in this thread, Mr Pass said 16v is the sweet spot. So you are close right now.

Quote:
You can try with a distortion analyzer for get the adequate voltage supply for your jets.
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
Jfet BOZ
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Old 12th September 2011, 01:13 PM   #1050
ramallo is offline ramallo  Europe
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Quote:
Originally Posted by timbarnes View Post
Ain't got one. Just a multimeter. But it is sounding good.
Without a distortion analyzer this post will be a good start point for you
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