"Unmodding" an ARC SP3 Preamplifier
- Thread starter BuzzK
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Blue Shadow
Waiting for Vintage Gear from this century
There is no mute relay in the SP-3 until the 3C version, don’t know about the rare B version. The C version has one on its new power supply board.
The switched outlets are there so that the preamp can be turned on then a minute later after the preamp stabilizes, the AC switched outlets are turned on.
Plugging a mute/timing relay into these outlets just makes me think the user doesn’t know how to use a system with a tube preamp that doesn’t have a mute relay. Glad you were able to put something in the pre to help out the owner.
Read the other day about an Omron H3Y-2 relay the has adjustable timing 0-60s that is avail on the river for less than 15 that would work. Comes with a socket. I’m considering putting one in my SP-3 not C.
The switched outlets are there so that the preamp can be turned on then a minute later after the preamp stabilizes, the AC switched outlets are turned on.
Plugging a mute/timing relay into these outlets just makes me think the user doesn’t know how to use a system with a tube preamp that doesn’t have a mute relay. Glad you were able to put something in the pre to help out the owner.
Read the other day about an Omron H3Y-2 relay the has adjustable timing 0-60s that is avail on the river for less than 15 that would work. Comes with a socket. I’m considering putting one in my SP-3 not C.
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tubelectron
Super Member
Yes. No mute relay in my ARC SP3A-1 preamp too.
But since I use it with my ARC D-76 power amp, there's no issue, nor with my DIY tube amps.
Otherwise, you start the preamp --- and --- then --- after --- you start the power amp : you do the timer by yourself !
T
But since I use it with my ARC D-76 power amp, there's no issue, nor with my DIY tube amps.
Otherwise, you start the preamp --- and --- then --- after --- you start the power amp : you do the timer by yourself !
T
My Bottlehead and the very modified PAS work that way, both are cathode followers with no mute relay. Just turn it on, give it a few, then turn on the power amp. A big part of why the Moscode is in my main rig is because it has a mute relay. Lets me hit one switch to bring everything up or down and nothing makes any funny noises. The other two wouldn't play nicely.
Be careful, the timer"Omron" relays on e__y and amazon are not Omron- they are fakes just like most of the ALPs blue velvet pots not purchased from trusted sources. Infact I would put a lot of money on the likelihood of any ALPs or Omron on amzon or e___y being fakes. FYI I found out the hard way. They are amazingly good replicas though!
Blue Shadow
Waiting for Vintage Gear from this century
Only thing left out is the quality, longevity and ability to work properly for the thousands of cycles the real ones are designed to accomplish. I was surprised by the difference in price, fake Amazon units vs Digikey/Mouser relays.
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If its just shorting the outputs to ground until the timer kicks, its not really being stressed. Its handling milliamps of low voltage and not breaking any sort of voltage or current since it will have stabilized by the time the relay opens.
probably not wise to use this for any sort of demanding application but a cheapie in this spot wouldn't be any big concern. Just get a socketed one to allow for easy future replacement.
probably not wise to use this for any sort of demanding application but a cheapie in this spot wouldn't be any big concern. Just get a socketed one to allow for easy future replacement.
Well, I have used the E___y and amazon types and take it fwiw- they are trouble they are $10 on e___Y and $200 at digikey. While they are not in a critical cct. You will be replacing them in short order. I like the idea of the cct board and 555 timer that can be used inside the unit. Good winter project that I will try to design on a pcb and make available.
On the other hand, the manual gives instruction and being I am an old f__rt I am used to following orders- just wait to turn on the amp during start up for a few minutes and use the right sequence.
The fakes are really good lookin' though.
On the other hand, the manual gives instruction and being I am an old f__rt I am used to following orders- just wait to turn on the amp during start up for a few minutes and use the right sequence.
The fakes are really good lookin' though.
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Blue Shadow
Waiting for Vintage Gear from this century
Been doing it this way for 45 years. Not hard to do.