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Old 9th April 2011, 07:48 PM   #951
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I've borrowed a Slagle 14 way inductive volume control, but need to wire it up. I intend to put that before the 26 stage, out of the CDP. More to come!

andy
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Old 9th April 2011, 08:14 PM   #952
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Hi Andy,

this might work, depending on your CDP. I never was very happy with the sound of inductive volume controls, when driven by Opamp output stages or cathode followers. So don't dismiss TVCs if you don't like the sound after you tried it this way. If it doesn't work well it is most likely the CDP's output stage which cannot cope well with an inductive load.

Best regards

Thomas
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Old 14th April 2011, 08:39 AM   #953
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Quote:
Originally Posted by dvb-projekt View Post
Got the refusal from AE-Europe today. So no UTC HA-133 replica

Any concerns to use the Lundahl LL1660/5mA for the #26 with 150V B+ and -9V Bias?
You could get the UTC HA-133 replica done by Electra Print. I once check with Jack@EP about this and he confirmed he has the spec to build it.

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Old 14th April 2011, 08:46 AM   #954
Kriskom is offline Kriskom  Indonesia
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YES, exactly.
I hav one pair wound by Jack , same specs 15K/600 Ohm , oprimary equivalent around 220Henry, but with higher primary DC current (16mA) than the HA133 or UTC A25.

It safeguard yu better than the HA133/A25 which max primary DC current is just only 8mA....rather tight when encountering sudden music transients.

They sound fabulous, bit sweeter and bit "polite" than the UTC's - more dynamic - as the core is not permaloy as used by the old UTC. Yu can ask Jack too, but the price wuld be much higher.

Paul
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Old 14th April 2011, 07:38 PM   #955
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Quote:
Originally Posted by Kriskom View Post
YES, exactly.
I hav one pair wound by Jack , same specs 15K/600 Ohm , oprimary equivalent around 220Henry, but with higher primary DC current (16mA) than the HA133 or UTC A25.

It safeguard yu better than the HA133/A25 which max primary DC current is just only 8mA....rather tight when encountering sudden music transients.

They sound fabulous, bit sweeter and bit "polite" than the UTC's - more dynamic - as the core is not permaloy as used by the old UTC. Yu can ask Jack too, but the price wuld be much higher.

Paul
Permaloy core is almost double the price of normal iron. But for sure EP products well worth the price.
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Old 18th April 2011, 05:03 AM   #956
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Quote:
Originally Posted by coolzero View Post
You could get the UTC HA-133 replica done by Electra Print. I once check with Jack@EP about this and he confirmed he has the spec to build it.

Electra-Print.com High-Fidelity Audio Tranformers and Tube Amplifiers
Hi coolzero,

thanks for the advice.
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Old 23rd April 2011, 06:17 AM   #957
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Originally Posted by coolzero View Post
Hi All,

I am in the process of completing Phaeton RC 26 preamp published on VT52.com site (Jim de Kort) as my latest DIY project. But still I am little puzzled with few things with my current project. Hope someone could provide an expert advice to me to figure out those.

One thing I am confused with is the hum coming out from B+. I figure out it is something to do with the grounding however. Lately I found out that if I ground the filament negative with B+ negative with 470uf capacitor, the hum is almost disappearing. But not sure whether this method is right or safe because what I did was sheer coincidental . Need advice on this. I used separate power rail using a SMPS for filament and both filaments were connected serially with 3V supply. Only connection for B+ negative from this rail is 470uf negative to negative (capacitor + to filament's negative and capacitor - to B+ negative).

Second thing I am puzzle with is the bias supply. Should I use separate 12 V supply for bias for 26 tube or should I use voltage divider to get the bias supply? Where exactly should I connect the bias voltage in this schematic?

Greatly appreciate if someone could clarify these for me.

Click the image to open in full size.
Hi coolzero,

""...Only connection for B+ negative from this rail is 470uf negative to negative (capacitor + to filament's negative and capacitor - to B+ negative)....""

In your diagram, there is already a 470uF capacitor, connected between GND and three resistors.

Did you add one more 470uF capacitor?? If so, could you show it on a diagram please??

Thankyou,

King
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Old 4th May 2011, 02:00 AM   #958
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hi guys

i would an opinion on how i better off maximizing the use of the choke in psu for #26

i have 4 choke. 2pcs of 20mH dan 2 pcs of 10mH.

which one is better option?
1. use them as CLCLC for B+ as well as for the ground
2. use them each channel gets its own CLCLC and star connection for the ground

thanks in advance
erwin
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Old 4th May 2011, 03:11 AM   #959
Gluca is offline Gluca  Italy
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did you say mH or maybe you meant H? mH are of no use for B+, maybe you can recycle them for the filament.
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Old 4th May 2011, 03:18 AM   #960
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Hi Gluca

Sorry for typo. They are 20H(2pcs) and 10H(2pcs). I bought them to be used in B+

Last edited by milen007; 4th May 2011 at 03:23 AM.
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