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Old 14th April 2011, 07:55 PM   #1
gychang is offline gychang  United States
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Default do I need vintage preamp?

I have a t-amp (power amp) that I like to use but has only one RCA input. I want to use it for my PC (music files) and my desktop CD player and want to add volume/input selector.

I can see 3 major possibilities.

1. is there a "radioshack" like product, with volume/RCA selector for cheap?
2. is there a DIY product (I can solder but can't read schematics etc)
3. Possibiy a vintage preamp on craiglist.

thanks in advance, will appreciate input.

gychang
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Old 14th April 2011, 08:36 PM   #2
amt is offline amt  United States
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For $50 you can build a nice passive attenuator with input selection. An Alps pot, three sets of RCAs and a toggle switch should sound much better than a beat up old preamp and be far more compact.

amt
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Old 14th April 2011, 08:44 PM   #3
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Passive is good, and have a friend help you wire one up.
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Old 14th April 2011, 08:52 PM   #4
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Quote:
Originally Posted by amt View Post
For $50 you can build a nice passive attenuator with input selection. An Alps pot, three sets of RCAs and a toggle switch [...]
you could also consider this thread (if you want to go fancy and maybe have remote control) - note that his is also passive unless you decide to build an active buffer...

otherwise, amt's correct. for very little money and just a few parts you can build a decent selector and passive volume.

A "vintage" preamp is also OK if it's more to your taste, or you decide you want more features. But where's the fun in that ;-)
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Old 14th April 2011, 09:18 PM   #5
gychang is offline gychang  United States
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Quote:
Originally Posted by amt View Post
For $50 you can build a nice passive attenuator with input selection. An Alps pot, three sets of RCAs and a toggle switch should sound much better than a beat up old preamp and be far more compact.

amt
any chance on the website that has the correct parts for the items u mentioned?, I have several RCAs, but no toggle switch, and do have a Alps pot laying around.

gychang
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Old 14th April 2011, 10:28 PM   #6
badman is offline badman  United States
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Quote:
Originally Posted by gychang View Post
any chance on the website that has the correct parts for the items u mentioned?, I have several RCAs, but no toggle switch, and do have a Alps pot laying around.

gychang
PM me and swing by the badshack, I can help you get this together. I'm in Tustin. Saturday's probably good.
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Old 14th April 2011, 11:15 PM   #7
amt is offline amt  United States
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Heres a quick wiring diagram. The best toggle around is the Tocos sold by Percy Audio and the worst are the ones sold at Ratshack.

Keep the wiring as short as possible and make sure the RCAs are isolated from the chassis (if its metal).

amt
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Old 15th April 2011, 12:26 AM   #8
gychang is offline gychang  United States
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Quote:
Originally Posted by amt View Post
Heres a quick wiring diagram. The best toggle around is the Tocos sold by Percy Audio and the worst are the ones sold at Ratshack.

Keep the wiring as short as possible and make sure the RCAs are isolated from the chassis (if its metal).

amt
thanks so much!, even I can follow this diagram, will order the DPDT (on/on, NOT on/off/on, right?) as u suggested. It will be in a small wooden case, the grounds on the RCA has to be soldered together? Thanks, again, I will do this. gychang
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Old 26th April 2011, 01:40 AM   #9
JoeDJ is offline JoeDJ  United States
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What if I wanted to make a 4 input selector without a volume control?
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Old 26th April 2011, 02:51 AM   #10
gychang is offline gychang  United States
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Quote:
Originally Posted by amt View Post
Heres a quick wiring diagram. The best toggle around is the Tocos sold by Percy Audio and the worst are the ones sold at Ratshack.

Keep the wiring as short as possible and make sure the RCAs are isolated from the chassis (if its metal).

amt
It works!!, I managed to follow your diagram, and soldered the RShack cheapie and Alps pot and it is dead silent in the background and music is glorious!!, thanks. Now I want to try 3RCA input, can u recommend a part?, seems like RShack and Partsexpress don't carry and I would like some recommendation, I will try some good ones this time for hopefully for my reference build. My soldering skills have improved and I am starting to get hang of this.

Thanks again amt. I will put up my pictures may be tomorrow night, just pure music without any hum, it is dead silent during music pause...

gychang

Last edited by gychang; 26th April 2011 at 02:53 AM.
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