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Old 16th September 2009, 09:30 AM   #1
jev is offline jev  Netherlands
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Default New input for UCD400 ?

Hello,

I have tried to replace the input opamps of my UCD400 but I have damaged the print

But since I already wanted to improve the input I am looking for a good input buffer/gainstage with the following specs:
  • Single ended input
  • Balanced output
  • Gain (I will use a stepped attenuator)

I am thinking of using a tube with an output transformer. Does anyone have a good schematic?

The other thought I had was to use only an input transformer. But whch one and how should I wire it?

I will wire the output of the new stage to the already removed coupling capacitors (these were bipolars).

Thanks!
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Old 17th September 2009, 09:16 AM   #2
jev is offline jev  Netherlands
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Default Interstage

Is it possible to use the first stage as input?

http://www.digitalakuten.com/circuit.../ralph-amp.htm
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Old 21st September 2009, 06:03 PM   #3
Koifarm is offline Koifarm  Netherlands
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Hey, i never use the opampstage of the hypex modules. If your preamp can drive 4,5 Vrms max to 1k8 you do not need any amplifying.

If you like transformer input use a 1:5 transformer from lundall.

Do not use single ended to symmetrycal conversion by tubes this give no better sound then single ende tube input like this:

Hybrid Hypex UCD

Ronny
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Old 22nd September 2009, 08:38 AM   #4
jev is offline jev  Netherlands
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Default Pass input

Thanks Koi.

I'd like to have a lot of gain in the chain in combination with volume control at the pre and amp. I think I wil use a Pass bosoz as input. I hava already ordered the pcb's...

When the project is finished - which might take some time - I will report back.
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Old 22nd September 2009, 09:28 AM   #5
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Quote:
Originally Posted by jev View Post
When the project is finished - which might take some time - I will report back.
Please do.
I recall reading somewhere that the big man himself (Bruno Putzeys ofc ) in some cases opts for a discrete input stage for his UcD amps.

Last edited by TheShaman; 22nd September 2009 at 09:36 AM.
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Old 22nd September 2009, 09:35 AM   #6
jev is offline jev  Netherlands
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Default UCD400 for subs

Yes, I am also using a pair of UCD400's (I think the better version) for my subwoofers. I always have the feeling they could be more dynamic. But that can also have to do with the woofers (JBL 2203a) that have quite heavy cones.
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