home theatre bypass feature

korabetsni · 8th October 2011, 12:59 PM

hello,
I am going to buil a tube line preamplifier with remote controlled input and volume. I have already made the remote controlled input (relay) selector and volume control. I will have a mute and HT bypass relay also.
I know how to connect the mute relay between the preamp and the output but i don't know how to connect the HT bypass relay. The preamplifier output must go to a relay which connects the output either to the bypass input or the tube preamp output. But what other components (resistors or caps) i must to use so i will not have any strange noises from my speakers when i'll change the HT bypass relay state?
I am posting a diagram of what i wanna to do. Can someone help me with this?

Bengali · 9th October 2011, 12:17 AM

Hi,

I would make the HT bypass indepedant of the preamp.

I've seen retail units that require the preamp to be on while in HT mode.

To me, that's a waste of tube life especially if you have paid a premium for the tubes.

Make the HT relay always active. I would not worry about noise. I would think before you start up your system, you will either watch movies or music, so make the mode selection before turning on your amps.

I'm made a passive external source selector to switch between the AVR and tube preamp. So I make the switch before turning on the amps.

Hope this helps you

korabetsni · 9th October 2011, 05:28 AM

The ht relay will connect the output to the ht input when the preamp is off for the reason you said. But i am concerning about click noises when the preamp will be on and i change the ht relay state or when i shut down the preamp an the relay changes state.

Bengali · 9th October 2011, 05:24 PM

I would then put the Mute Relay switch at the Line Output that goes into the amp. Unmute it after the making the switch between HT/Music.

korabetsni · 10th October 2011, 04:28 AM

Yes that is good solution i am thinking about. I am searching schematics of any commercial preampifier with a HT bypass feature so i can see how the HT bypass is implemented but i cannot find any. Do you have or know where i can find one?

Bengali · 11th October 2011, 02:29 AM

I have not seen any actual circuits via google.

They are pretty basic circuits. Even in the high end units
they are just switching sources or setting the pre at unity gain.

I'm sure some are microproc. based and other's just simple circuits.

maybe a 555 one shot timer when you select between sources,
it mutes it for however long you want it, then unmutes.

I'm using a grahill rotary switch to between the AVR and PRE,
works great.

korabetsni · 11th October 2011, 05:09 AM

hello,
Yesterday i tested the swithing between 2 sources with one relay and there aren't any click sounds, so i will leave the circuit as is.(the HT bypass relay on the exit without the need of muting every time the relay changes)
thank you

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
New Home Theatre Sub	dark_avenger	Subwoofers	11	29th December 2007 02:28 AM
Home Theatre Audio	Dynsdale	Digital Source	10	24th June 2007 05:59 PM
Home Theatre	bhg41088	Multi-Way	4	16th August 2004 01:32 PM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read

9th October 2011, 12:17 AM	#2
Bengali diyAudio Member Join Date: Oct 2006	Hi, I would make the HT bypass indepedant of the preamp. I've seen retail units that require the preamp to be on while in HT mode. To me, that's a waste of tube life especially if you have paid a premium for the tubes. Make the HT relay always active. I would not worry about noise. I would think before you start up your system, you will either watch movies or music, so make the mode selection before turning on your amps. I'm made a passive external source selector to switch between the AVR and tube preamp. So I make the switch before turning on the amps. Hope this helps you

9th October 2011, 05:28 AM	#3
korabetsni diyAudio Member Join Date: Mar 2011	The ht relay will connect the output to the ht input when the preamp is off for the reason you said. But i am concerning about click noises when the preamp will be on and i change the ht relay state or when i shut down the preamp an the relay changes state.

9th October 2011, 05:24 PM	#4
Bengali diyAudio Member Join Date: Oct 2006	I would then put the Mute Relay switch at the Line Output that goes into the amp. Unmute it after the making the switch between HT/Music.

10th October 2011, 04:28 AM	#5
korabetsni diyAudio Member Join Date: Mar 2011	Yes that is good solution i am thinking about. I am searching schematics of any commercial preampifier with a HT bypass feature so i can see how the HT bypass is implemented but i cannot find any. Do you have or know where i can find one?

11th October 2011, 02:29 AM	#6
Bengali diyAudio Member Join Date: Oct 2006	I have not seen any actual circuits via google. They are pretty basic circuits. Even in the high end units they are just switching sources or setting the pre at unity gain. I'm sure some are microproc. based and other's just simple circuits. maybe a 555 one shot timer when you select between sources, it mutes it for however long you want it, then unmutes. I'm using a grahill rotary switch to between the AVR and PRE, works great.

11th October 2011, 05:09 AM	#7
korabetsni diyAudio Member Join Date: Mar 2011	hello, Yesterday i tested the swithing between 2 sources with one relay and there aren't any click sounds, so i will leave the circuit as is.(the HT bypass relay on the exit without the need of muting every time the relay changes) thank you

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)