Will a tube preamp play nice with a F1? - diyAudio
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Old 7th March 2009, 08:44 PM   #1
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Default Will a tube preamp play nice with a F1?

I'm building a parafeed 396a preamp. I have also just ordered a set of F1 clone boards to see what all the huff is about. My question is are they going to play nice together or does the F1 need a special pre to make it happy? Thanks.
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Old 8th March 2009, 09:57 PM   #2
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No one has an answer? ON this forum? All I need to know is how much gain I need and what output impedance I need.
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Old 8th March 2009, 11:30 PM   #3
DougL is offline DougL  United States
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G,

The F1 has a balanced input with 1 Meg ohm to ground.
Figure its in parallel with the 400k and 500k. Still looks north of 150K total. Tube preamp should love that.

There is a 20V zener on each input, so that limits the output to an absolute maximum of 12Vrms or so.

My sense is that the gain of an F1 is much more dependant on the speaker and its impedance than normal.

What drivers / speakers are you planning to use?

Hopefully others can furnish practical experience.

HTH

Doug
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Old 9th March 2009, 02:44 AM   #4
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Default Not a problem

Unless you have a really wimpy pre, the F1 is a very easy load. Dick Olsher, in specific, used this combination in his review of the F1. 6 Moons may have also.
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Old 9th March 2009, 05:57 AM   #5
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I am building 4 channels of Aikido preamp to drive my F1. The F1 is as easy to drive as it gets but has no gain. You could build a 6SN7 gain stage relatively easily which is enough voltage gain. The speakers should be full range or I would ask, why an F1?
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Old 9th March 2009, 06:35 PM   #6
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Quote:
Originally posted by DougL
G,

The F1 has a balanced input with 1 Meg ohm to ground.
Figure its in parallel with the 400k and 500k. Still looks north of 150K total. Tube preamp should love that.

There is a 20V zener on each input, so that limits the output to an absolute maximum of 12Vrms or so.

My sense is that the gain of an F1 is much more dependant on the speaker and its impedance than normal.

What drivers / speakers are you planning to use?

Hopefully others can furnish practical experience.

HTH

Doug

Thanks for the reply Doug. I will be using the F2 (instead of the F1) with a pair of BR Fostex FE206E speakers with phase plugs. Hopefully this will be a nice combination.
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Old 9th March 2009, 06:37 PM   #7
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Thank you everyone for your replies. It seems I will be using a F2 in the future and not a F1. I will be using them with Fostex FE206E drivers with phase plugs installed. Any advice?
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Old 9th March 2009, 08:46 PM   #8
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G,
I have been using F1 with Fonkens (fostex127e) driven directly from squeezebox.
I have also tried 24v aikido in front of f1 but way to much gain!

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Old 10th March 2009, 06:23 PM   #9
MikeW is offline MikeW  United States
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I have an Aikido and it runs the F1 fine. I do like the F3 better with the feedback resister @ 470K.
It sounds great with the Audio Nirvana 8 inch.
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Old 15th March 2009, 11:46 PM   #10
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Akido would be great as would one of the 12B4A circuits found on threads here on diyaudio.
Happy soldering!
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