Will a tube preamp play nice with a F1?

G · 7th March 2009, 08:44 PM

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.

G · 8th March 2009, 09:57 PM

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.

DougL · 8th March 2009, 11:30 PM

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

Jon Ver Halen · 9th March 2009, 02:44 AM

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.

khundude · 9th March 2009, 05:57 AM

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?

G · 9th March 2009, 06:35 PM

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.

G · 9th March 2009, 06:37 PM

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?

Pathmark · 9th March 2009, 08:46 PM

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!

pathmark

MikeW · 10th March 2009, 06:23 PM

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.

amp-guy · 15th March 2009, 11:46 PM

Akido would be great as would one of the 12B4A circuits found on threads here on diyaudio.
Happy soldering!

7th March 2009, 08:44 PM	#1
G diyAudio Member Join Date: Apr 2002 Location: Belleville, IL.	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. __________________ Gavin

8th March 2009, 09:57 PM	#2
G diyAudio Member Join Date: Apr 2002 Location: Belleville, IL.	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. __________________ Gavin

8th March 2009, 11:30 PM	#3
DougL diyAudio Member Join Date: Feb 2004 Location: Wheaton IL. Blog Entries: 28	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 __________________ Scienta sine ars nihil est - Science without Art is nothing. (Implies the converse as well) Mater tua criceta fuit, et pater tuo redoluit bacarum sambucus

9th March 2009, 02:44 AM	#4
Jon Ver Halen diyAudio Member Join Date: Aug 2004 Location: Chicago area	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. __________________ Jon Ver Halen Lowther-America

9th March 2009, 06:37 PM	#7
G diyAudio Member Join Date: Apr 2002 Location: Belleville, IL.	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? __________________ Gavin


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9th March 2009, 05:57 AM	#5
khundude diyAudio Member Join Date: Sep 2006	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?

9th March 2009, 08:46 PM	#8
Pathmark diyAudio Member Join Date: Jan 2007	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! pathmark

10th March 2009, 06:23 PM	#9
MikeW diyAudio Member Join Date: Sep 2002 Location: North of Boston	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. __________________ MikeW

15th March 2009, 11:46 PM	#10
amp-guy diyAudio Member Join Date: Oct 2004 Location: utah	Akido would be great as would one of the 12B4A circuits found on threads here on diyaudio. Happy soldering!

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