Bottlehead Forum
Bottlehead Kits => Legacy Kit Products => Submissive => Topic started by: altec604e on January 24, 2014, 05:34:34 AM
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Hi,
Bringing in transistor based amplifers on the forum is probably a NO-NO, but I need some help here.
I have a pair of Quad 303`s that runs as separate monoblocks.
I also have a Submissive pre.
I just found this site :
http://www.briarsfield-hifi.co.uk/quad_303_overview.htm
I want to try out my Submissive as a passive pre for my Quad 303`s.
This guy says that a pair of Quad 303`s = 25k Ohm load.
I do not understand this term, but maybe someone out there could tell me if the submissive is a good match or not.
All help will be appreciated.
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It's kind of funny, as the guy on that page uses a 100K passive preamp to drive his 303's, which is not such a stellar idea.
The Submissive will work with your 303's, but a preamp with lower output impedance would be helpful in the long run.
-PB
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Hmm..
What output specs do the Submissive pre have ?
I know there are three settings I can switch between on my Quad 303`s ( they`ve been modified with new boards )
The input sensitivity can be set to 0.5mV , 1.5mV and 5mV.
Has these settings something to do with Gain ?
To be honest I do not know where the 25K ohm load comes into the picture.
This is why I`m posting....
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The circuit of the 303 is online, and shows an opamp with 22K to the virtual ground , so 25K sounds reasonable.
What I found on the web says it's normally 0.5 volt, not 0.5 millivolt. The simplest and hence most likely modification would be a series resistor, raising it to 75K and 125K for the 1.5v and 2.5v respectively. You'd need a circuit of the modification to be sure, though.
A classic from the early days, before PNP power transistors were available to make complementary symmetry circuits. There's another cult classic amp with that type of circuit; I forget the brand.
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You are correct:
The specs are not in milivolt , but volt.
So there are one jumper in each 303 to switch between 0.5 Volt and 1.5 Volt and 5 Volt input sensitivity.
Thank you so much for checking this out...
but cant say I`m following you...
Do you mean changing the circuit of the submissive or my quad 303`s ?
I`m hoping you`re meaning the submissive....
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I`ll leave it be.
Thanks for the input !
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Oh - sorry I was not clear. I mean that whatever modification was done to the Quad 303 would more likely than not increase its input impedance (making it more suitable for the Submissive) when set for a higher input voltage.
I would not hesitate to use the submissive - the recommendation is for a 30K minimum but it's been used successfully with 25K.
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Understand .
I`ll try the submissive with my Quad 303`s.
If this works well I will build a second passive pre for my Quad equipment.
Thanks !