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PostPosted: 04 Mar 2010, 02:29 
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KrammeAcoustics wrote:
mwhouston wrote:
Stick with the tubes but upgrade the passive components and move to an OPA2134 for the buffer/output chip.

Could it be worth upgrading the PT2308 -> OPA2604 ? or are the differenses in soundquality between OPA2134 and OPA2604 to small to mention, so it doesn't matter ? :trumpet:

In other forums, i have seen people prefering the 2604.

Ebay prices: 2134 and 2604 = 5 - 10 US $. 8-)

There is decimal point the difference. The OPA2134 has ten times less distortion. You probably couldn't pick the difference by just listening. But when has that ever stopped upgrading??

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PostPosted: 05 Mar 2010, 23:41 
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Joined: 29 Aug 2008, 11:55
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Gio,
how is the sound level between Left and Right channel ?
isn't it Right channel is louder ?

Cal


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PostPosted: 06 Mar 2010, 09:25 
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HI Cal, the trim pots at the input (VR1 and VR2) are use to set the balance.

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PostPosted: 08 Mar 2010, 03:15 
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Location: USA
Hi, Gio!
I tried my K272, gift from Ben /thanks,Ben!/, like lampisator for power trans. stage, and they sound very good,
but with +U=18v!!! /With +9v there is some haze./
6418 /K272/ can be used for integr. and trans. power stages!

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Projects: OTL 6AS7 Gen, Electric, SEs 2A3 RCA, 300B JJ, 6S4S, 4P1L, EL11 Telefunken, 6AS7 RCA, 6S33S, 6S41S, 6S19P, PP 6005 Gen. Ellectric , headphone ampl. OTL Loftin White 6AS7 RCA....SE E84L& E80CC Siemens&Tel-n.
http://azazello-sound.blogspot.com/


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PostPosted: 09 Mar 2010, 21:18 
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I took the K272A up to 18V via two 9V batteries in series and all seems good :twisted:. The LED is much brighter but did not burn out :xfingers:. The L4949 regulator is rated up to 28V so we are good there. And the heater is working fine. And it does sounds better! :headphones:

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PostPosted: 10 Mar 2010, 01:50 
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Gio wrote:
The LED is much brighter but did not burn out
A good thing the LED switches off after a second after turning on the amp. :mrgreen:

I'm gonna try to power it this way too.


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PostPosted: 10 Mar 2010, 02:55 
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Beftus wrote:
Gio wrote:
The LED is much brighter but did not burn out
A good thing the LED switches off after a second after turning on the amp. :mrgreen:

I'm gonna try to power it this way too.

This is a no-brainer easy fix. A 200K ohm resistors in series with your fav. coloured led. That easy. And a 0.01uf cap across the noisy bastard right at the LED.

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PostPosted: 10 Mar 2010, 06:29 
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mwhouston wrote:
And a 0.01uf cap across the noisy bastard right at the LED.
Noisy bastard? Huh, who? Please explain!


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PostPosted: 10 Mar 2010, 06:45 
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Beftus wrote:
mwhouston wrote:
And a 0.01uf cap across the noisy bastard right at the LED.
Noisy bastard? Huh, who? Please explain!

LED

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PostPosted: 10 Mar 2010, 14:19 
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Gio wrote:
And it does sounds better! :headphones:

Please explain it to me like I'm a six year old... What does a higher plate voltage do? Better S/N ratio? Does a higher plate voltage always equal better sound?

Thanks!


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