improving a ST70 Triode

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improving a ST70 Triode

Postby mati1979 » Wed Nov 11, 2009 6:48 pm

Hi, i have a Triode ST-70.

Im very happy.

im sorry for my english !

with solen caps.

I want improving a amp. Im thinking about doing upgrade in caps (solen)
wich could be better ?

Or need spend in another part ?
change the caps in pre is justified ?

I can see improvement in the sound with other caps ?

now im listening with L100A JBL and pre Bryston.

my complete system is:

ST-70 (svetlana, RCA, and Sovtek tubes)
PRE Bryston 11B
cd player Pioneer Elite PD-M59 (mid quality i think)
L100A JBL Speakers.

I want to improve, what should I change first ?

im sorry for my english !
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Postby dcriner » Wed Nov 11, 2009 7:54 pm

I doubt changing the caps will produce any audible difference.
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Postby mati1979 » Wed Nov 11, 2009 7:57 pm

i think, my next change : "speakers" xxxxx or cd player

.
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Postby mati1979 » Wed Nov 11, 2009 8:42 pm

I tried removing the pre bryston (of circuit) and a sound is very more clean!
this is normal ?
a pre bryston not is good ?
a problem is a volume. My min. vol. in a cd player is high.

This circuit is normal ? (cd player - tube amp without pre) ?
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Postby kheper » Wed Nov 11, 2009 9:11 pm

mati1979 wrote:I tried removing the pre bryston (of circuit) and a sound is very more clean!
this is normal ?
a pre bryston not is good ?
a problem is a volume. My min. vol. in a cd player is high.

This circuit is normal ? (cd player - tube amp without pre) ?


It is normal for the volume to be high when driving the amp with a CD player as the source. The CD player is putting out 1 - 1.5V. You are driving the amp to its specs.

http://www.dynakitparts.com/store/speci ... ST70/?id=2

INPUT SENSITIVITY: 1.3V FOR 35 WATTS OUTPUT


Some high-end CD players have a built-in volume control. You need a pre-amp, a CD player with a volume control or a volume control in the amp to reduce the output to normal listening levels.

Most people listen to music at 10-15 Watts, not 35 Watts.
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Postby kheper » Wed Nov 11, 2009 9:37 pm

I have an idea to directly connect a line-level source to the st70. This should achieve a near normal listening level with no pre-amp.

The amp could be run in triode mode and the B+ under-volted, so the amp operates at < 15W/ch continuous. However, with a ~1.5V input signal, the amp might be close to clipping. Pad the input of the amp further?

I still like a volume control for an amp.
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Postby burnedfingers » Thu Nov 12, 2009 6:01 am

I doubt if there is any sonic difference between using the Bryston and running without it. If memory serves me correctly the Bryston is a fully complimentry design similar to the Gas and SAE. These are very neutral in there sonic character. If you feel a need to run without a preamp then consider a good set of pots probably around 10K will do or build a resistive control with a number of different settings. I like a 24 position control. There is no way to judge the difference between having the preamp in the circuit and trying to run the system without any type of resistive control. A proper A/B would be the same level settings from both the preamp and a resistive control going to a A/B switch that would allow one to make an evaluation between the two.
Just my .02
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Postby mati1979 » Thu Nov 12, 2009 1:44 pm

i have saw:

"Less connections always sound better"

why not exist a mini box with simple pair pots for only control
vol and avoid a preamplifier ?

"less......" if this sentence is true, why all audiophiler not use a direct cd player - power amp ?
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Postby nyazzip » Thu Nov 12, 2009 1:53 pm

preamps allow many types of media(tape/radio/CD/vinyl/streaming digital) to interface with the power amp. some signals are too hot and need to be cut(CD) while others are too weak and need to be amplified(vinyl).
at least that is my view
<i>the poor craftsman blames his tools</i>
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Postby mati1979 » Thu Nov 12, 2009 2:24 pm

another sentence might be:

"sometimes worse directly use the signal?"

?

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