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Old 20th November 2011, 04:32 PM   #421
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Hmm....

'Less refined'

I wonder, if the phase-shifts that are probably happening at these lower frequencies caused by the PSU caps in series with the signal without the CT connected, are causing the bass differences that are a pleasing effect for you....

Or maybe I'm just talking crap!--Sound is just so subjective and so difficult to describe in words!

I would have thought without the CT connected, the bass would be 'wolly' or boomy/vague sounding, less defined....
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Old 20th November 2011, 04:38 PM   #422
M Gregg is offline M Gregg  United Kingdom
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Quote:
Originally Posted by Alastair E View Post
Hmm....

'Less refined'

I wonder, if the phase-shifts that are probably happening at these lower frequencies caused by the PSU caps in series with the signal without the CT connected, are causing the bass differences that are a pleasing effect for you....

Or maybe I'm just talking crap!--Sound is just so subjective and so difficult to describe in words!

I would have thought without the CT connected, the bass would be 'wolly' or boomy/vague sounding, less defined....
Its hard to describe but here we go...there seems to be less bass and its grainey buy comparison.. not so smooth sounding..hard on the ear..

I don't know if this makes sense but its less musical..

The problem is this could be the components used etc..
I'm almost tempted to put a couple of flying leads and variable power resistor and try different settings,,to see what the effects are..
We know that there is an effect if its disconnected and put back...so I have to assume that I am hearing something..what that is I do not know..

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M. Gregg
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Old 20th November 2011, 04:46 PM   #423
M Gregg is offline M Gregg  United Kingdom
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Alastair,

The effect is the same as the sound of new tubes..hard to describe
Before and after burn in!

I'm going to listen for a while and see if it changes or I get used to the sound..

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Old 20th November 2011, 04:57 PM   #424
M Gregg is offline M Gregg  United Kingdom
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OK I have only listened for a short time..

I can tell exactly what it is....when the ct was disconnected there was a frequency shift from bass to treble..ie bass was light by comparison

Now there has been another shift...treble is less..bass is grainy maybe more but possibly moved lower down the scale

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Old 20th November 2011, 05:56 PM   #425
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Here you go, Some simple PSU layouts with descriptions....


http://www.audiodesignguide.com/my/ocl.jpg
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Old 20th November 2011, 06:05 PM   #426
M Gregg is offline M Gregg  United Kingdom
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Alastair,

I have fitted 300 Ohm and it sounds great hum is very very low in the speakers..
I would go so far to say I cannot hear anything in the one speaker
(I do mean can't tell its on, thought the speaker cable was disconnected)I guess with a bit of juggling of the 6633C's I could get it lower on the other side...

So I think this is the value I will stick with plus the unequal resistors..

To me the difference is chaulk and cheese..

Thanks for the links..for me the 1K in the PSU is now 300 Ohms..


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M. Gregg
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Old 20th November 2011, 06:13 PM   #427
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Did you try the old transformer as choke ploy...?
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Old 20th November 2011, 06:20 PM   #428
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Alastair..
Just thinking out loud here..

While after 4hrs listening to the OTL with Deadmau5 (for want of a better name)

deadmau5 "16th hour" - YouTube
Got to test the bass haven't you..

Shakes my laptop across the table.. and hammers the Alpairs into submission
Very deep bass....anyway..yes there are fuses and bypass caps just not on this pic...
Some discussion going on....
Sounds great!!







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M. Gregg
It is better to connect the center tap of the trafo right to the capacitors without the 1K resistor , and use a protection circuit for the loudspeakers to prevent any DC voltage that can destroy them .
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Old 20th November 2011, 06:29 PM   #429
M Gregg is offline M Gregg  United Kingdom
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Did you try the old transformer as choke ploy...?
Not yet work getting in the way...I will keep trying different things..and post what I find..

There is no question that with the resistors as they are the sound stage is way better...it closed in with the Ct direct connection..why I don't know at the moment...

There must be a reason for this I will try a few things..see what happens..

I have thought about a crowbar circuit that just plugs across the speaker..small module..

Also looking at the cheep choke idea...or electronic choke....so much to try..lol


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M. Gregg
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Old 20th November 2011, 09:20 PM   #430
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Gregg , you can play with the value of R16 470K , decrease it .
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