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Old 11th November 2005, 09:46 PM   #1
cryo is offline cryo  United States
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Question DIY pre-amp kit vote

I have digested oodles of info, and come up with three candidates for my first pre-amp kit:

Foreplay III from Bottlehead http://www.bottlehead.com/et/adobesp.../foreplay3.htm
Magic 5 SE from Mapletree http://hollowstate.netfirms.com/magic5.htm
AE-3 from audioelectronicsupply http://www.audioelectronicsupply.com...d_num=AE-3_KIT

I just finished my first diy project, a Cmoy headphone amp that actually worked first time out of the gate. Feel confident to step up to a pre-amp, but also convinced a kit would probably be a sane choice for a beginner. (The temptation to move up from 18V dc to a couple hundred is too much).

Any sage advice or opinions from those who have heard or built more than one of the above? Santa is bugging me to make a decision.

Any help would be very kind. Thanks in advance.
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Old 11th November 2005, 10:07 PM   #2
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You could build Franks 5692 line stage at a fraction of the cost of those on your list. Franks line stage will out perform them also.
Why not make it a true DIY project instead of someone elses borderline kit?
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Old 11th November 2005, 10:18 PM   #3
Celeste is offline Celeste  United States
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I have not heard any of them , I have built a few Bottlehead kits and can say that they are a pleasure to do business with. The general word is that the Foreplay III sounds as good or better then the II with all the usual mods ( CCS 's ,DC heaters, stepped antunators, designer output caps, PDMPS ) . There is an upgrade kit coming for the III so if you like to tinker , then you have a clear path. And then there is the Bottlehead Forum , one of the most civil places on the web. You may like one of the other choices better , but you won't go wrong with the bottlehead.

Have big fun building
Celeste
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Old 11th November 2005, 10:31 PM   #4
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I'd echo the DIY idea instead of a cheap kit. You'll spend less money, and have a better linestage when you're done.

The Guinevere linestage discussed at Audio Roundtable is a good and fairly simple start. It is quite versatile. Pick your gain requirement and go from there. Need a gain of ~20? try a 6SN7, want a little less, go 5687, less still, 7AH7, still less? 12B4 comes to mind at mu=6.5.

The schematic is here:
http://audioroundtable.com/GroupBuild/Projects/

I drew it, got some help from a few members, and there are more than a dozen of them around by now in one form or another. You're looking at ~$200 in parts, and your own labour. there is nobody to pay for the design, so your parts bill is the end of it.
cheers,
Douglas
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Old 11th November 2005, 11:32 PM   #5
Cassiel is offline Cassiel  Libya
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Hi,

if you don't mind spending more money go for the kit option. You don't need to search for a schematic( which one is better? there are hundreds....), you don't need to search for parts and the manual is dumb proof. But, on the other hand, you could easily have one better for half of the price.
If you go the DIY route just don't choose a complicated design, a simple line stage is SO easy to do and , generally, sound great.
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Old 11th November 2005, 11:42 PM   #6
Bryan is offline Bryan  United States
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I would (and did) personally build a 12b4a linestage. gain of about 5, simple, GREAT sounding, and fun!

You can cearch the schematic on this site...
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Old 11th November 2005, 11:45 PM   #7
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You might want to add the Transcendent Grounded Grid to your list to consider. At $499, not too far outside the price range you are looking at. A completely different approach than the other kits you list in that it uses a PCB instead of point to point.

Grounded Grid

The new foreplay looks really nice from a build perspective. I gave up rebuilding my foreplay 2 when I saw the 3 had come out. In any case I'm happy with my grounded grid.
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Old 11th November 2005, 11:57 PM   #8
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The Guinevere looks interesting, and isn't that different conceptually from Brant's 12B4 -- the SS loading bits could probably be added to it from the Guinevere and you'd have another version...

The Foreplay & the AES are 2 faces of the same topology, as is one of the Maple Tree modes. I've heard so many JoeListers comment on how their cicrcuit sounded better after converting an SRPP to common cathode that i'm leary of that.

For a kit in that price range, i vote for... The Grounded Grid.

dave
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Old 12th November 2005, 12:10 AM   #9
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The 12B4 with a resistive plate load can be done very easily. The Guinevere plate loads will drop its output Z from ~1kOhm to less than 100R which is a nice low number for driving almost *ANYTHING* and making cable salesmen poor.

If you want to play with the Grounded grid, you can adjust gain by putting a plate load onto the input section. You don't have to do anything with it, and if you have too much gain, you can increase it up to and past the value on the amplifying section. Think Schmitt inverter/Lont-tail-pair sort of thing.
cheers,
Douglas
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Old 12th November 2005, 03:58 AM   #10
amperex is offline amperex  United States
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Transcendent Grounded Grid at $499

Difficult to beat even with DIY designs.
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