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Old 31st July 2004, 11:55 AM   #11
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Basically if we could use a control group(same amps and same speakers) in which to use as a compare we could actually answer this question. That is of course if we had 100 blindfolded listeners.

I have listened to the Forplay and was not impressed so I didn't purchase the kit. I built the 5687 and used VR's in the power supply. The result was a very nice sounding linestage. I listened to a friends 12B4 and was blown away. I built it(12B4) and compared it to the 5687 and found it to be more natural sounding.

If I was to choose between the 5687, the 12B4, and the 5692 from Frank it would probably be a tie between the 5692 and the 12B4. Note* The 12B4 has yet to receive power supply upgrades (VR's) like the 5687 and 5692 have.

Note* My opinion here*****

I believe that when more time is spent in the design of the power supply the result is a better sounding piece. I believe in using VR's
in power supplies and I believe in regulated(Frank's circuit) as the best answer to power supply regulation. There is a night and day difference in the sonics when using good supplies.


Thanks Frank for the heads up on supplies.


Joe
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Old 1st August 2004, 03:59 AM   #12
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Thanks for all of the responses guys.

I was originally going to go with Joel Tunnah's 6sn7 design. But after hearing about and seeing Frank's design, I may go with that.

As far as the PSU goes I might do something different. I did like the simplicity of Joel's design (first project for me). Here I modified it by increasing the resistors to 680/3W to get the voltage down to approx. 249-250V and the second cap to 100uF. Does anyone see any problem with this?

Click the image to open in full size.

The attached txt file is in fact a PSU file for you to look at via Duncans PSU designer.


Thanks all,
Toyman
Attached Files
File Type: txt psu250.txt (181 Bytes, 142 views)
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Old 1st August 2004, 12:13 PM   #13
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HEY-Hey!!!,
WHy not just use a choke input PS filter? It will filter better than the two RC stages, and be a better load on the power tx too.
regards,
Douglas
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Old 2nd August 2004, 01:42 AM   #14
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Okay. I changed my mind again for now. Can anyone recommend (schematic) a PSU to use with Frank's 12B4 linestage?
I would like to use a full wave rectifier LCLC. I saw Frank's new PSU designs and they are a lot over my head. I am a newb ya know. Something similar to this would be great:

Click the image to open in full size.

Thanks guys,
Toyman
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Old 2nd August 2004, 03:22 AM   #15
zobsky is offline zobsky  India
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I used a 20uf 20H 200uf which was dead silent for my 12b4 preamp.

Doing this again, I would use a 20uF 20H 200uF coupled to two R-C stages to decouple the two channels somewhat. (R-C coz it's cheaper)

This would be a good place to start, .. try modeling it in PSUD to find optimum values, .. and to get your preamp working with a minimum of fuss

Then, you can play with regulation and all the other goodies. If you plan to do so, give a good thought to layout beforehand. In fact, I suggest building the PSU and the preamp in seperate chassis (less interference, more space, and you can always build new power supplies if you are a tweaker type)
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Old 2nd August 2004, 04:18 AM   #16
arnoldc is offline arnoldc  Philippines
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who else here built frank's 5692 pre? i am in the process of building and might need to ask some questions. of course, frank is always available as usual, but i don't want to "abuse" him
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Old 2nd August 2004, 04:26 PM   #17
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Zobsky,

You mean something like this?

Click the image to open in full size.


Frank any suggestions?

Thanks
Toyman
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Old 2nd August 2004, 06:28 PM   #18
zobsky is offline zobsky  India
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Quote:
Originally posted by Toyman_PA
Zobsky,

You mean something like this?

Click the image to open in full size.


Thanks
Toyman
close,.. but also include a smaller (10 - 20uF) cap before the choke followed by the 200uF and the RC stages , .. ( i think the rule of thumb was C -> L -> (10 x C) -> ..... )
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Old 2nd August 2004, 11:11 PM   #19
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Hi,

Quote:
close,.. but also include a smaller (10 - 20uF) cap before the choke followed by the 200uF and the RC stages , .. ( i think the rule of thumb was C -> L -> (10 x C) -> ..... )
Well, if it's a CLC filter that you want then, yes...
However, IMHO the LC filter type is the better suited one for audio purpose, YMMV.

Hammond Transformers as a nice overview of PS filter types with effeciency numbers:

HAMMOND

Quote:
Frank any suggestions?
Since you ask...If you'd use chokes iso of the Rs to split the PS you'd come pretty close to the ideal without actually using dual mono power PSs IMO.

Cheers,
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Old 3rd August 2004, 12:05 AM   #20
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Frank,

Honestly I am just looking for a simple PSU putting out ~260V to run into your 12B4 linestage. I am not looking for anything specifically (CLC, RC, LC). Since I can't find a schematic for vacuum tube rectified LCLC to get 260V (all that I can find are 250V), I tried my own on post #14 by taking an existing 250V and trying chokes with diff resistance ratings to get to ~260V.

To make it short, in your opinion will the power supply in post #14 work well with your 12B4 linestage? By working well, I mean good sound, not necessarily as good as your new PSU designs. But something that I can learn on and expand on in the future.

Thanks again for your time,
Toyman
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