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Old 31st July 2003, 05:27 PM   #1
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Default Need recomdations on a lineamp

I would like to build a differntial line amp. That's the easy part,
I would like to be able to drive a 300 ohm load with a 30vpp output . any ideas? I would like to keep it in the $300 range or so.

Thanks,

Woody AKA bob12345678
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Old 31st July 2003, 05:46 PM   #2
EC8010 is offline EC8010  United Kingdom
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Default Lumme!

30Vpk-pk into a 300R load! That's not a line amp - that's a small power amplifier (375mW)!
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Old 31st July 2003, 05:55 PM   #3
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Default Re: Need recomdations on a lineamp

Quote:
Originally posted by bob12345678
I would like to build a differntial line amp. That's the easy part,
I would like to be able to drive a 300 ohm load with a 30vpp output . any ideas? I would like to keep it in the $300 range or so.
Why 30Vpp into 300R?
And how much gain do you want / need it to have?
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Old 31st July 2003, 06:30 PM   #4
dhaen is offline dhaen  Europe
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Default Overkill..........

I believe that Frank has said that his beast does something like this...
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Old 31st July 2003, 07:07 PM   #5
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Hi,

Quote:
I believe that Frank has said that his beast does something like this...
35V P2P. Zo 47R.

No gain though, unity gain (.97 IIRC).

But where does this 300R Zin come from?

Cheers,
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Old 31st July 2003, 07:49 PM   #6
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Default Re: Lumme!

Quote:
Originally posted by EC8010
30Vpk-pk into a 300R load! That's not a line amp - that's a small power amplifier (375mW)!
Maybe Krell has started manufacturing headphones.
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Old 31st July 2003, 08:35 PM   #7
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30Vp-p at 300 ohms is around 100mAp-p.. 6AS7 CF would do it.

If you prefer iron, you could push a 6DJ8 into an OPT. 3:1 or 4:1 turns ratio would be enough.

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Old 31st July 2003, 09:02 PM   #8
Fuling is online now Fuling  Sweden
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What about a 6DJ8 SRPP cap coupled to a 230/2x33V 15VA toroid?

Im asking because I have the parts and I need a linestage.
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Old 31st July 2003, 09:16 PM   #9
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Hi,

Quote:
Im asking because I have the parts and I need a linestage.
I doubt you'd need the gain of the SRPP + the xformer though.

The advantage of the SRPP is reasonable gain with lower Zo than an anode follower.
No point of tacking on a xformer there IMHO unless you'd do it for a different set of reasons.

You could also build a White CF with the 6DJ8s, no gain but very low Zo and plenty of current to drive even the most silly cable lengths.

Cheers,
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Old 31st July 2003, 09:26 PM   #10
Fuling is online now Fuling  Sweden
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Well, my intention was to use the transformer to lower the gain (and output impedance).

The 6DJ8 would have a gain of about 30 (I guess), and the transformers has a ratio of roughly 3:1 with the secondasies in series. The gain would then be about 10, right? Still a bit high, maybe.
I guess Id rather go for a choke loaded 12B4A.
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