filter and tone toggles Audio Research SP-4 Preamp

When the switch for tone is up the tone controls are active. When the switch is down the tone controls are not activate. The same is true of the filter. Up the filter is working and down it is not.

This is nothing new. Even Japanese receivers had these controls in the '70s.

Where did you get the SP-4 and what amplifier are you using with it?

Thanks for the prompt answer, will run this in neutral mode, so those toggles will be down.

Finn14 from Audiogon sold me this built like a tank SP-4 and just wired it up on Oct 26 - wife's birthday - she says she likes the present I got for myself on her birthday! It ran me around $500 bucks and so eliminated my days with a sub $1000 entry level system.

I have listened to my setup for 2 years with an SAE 2900 that I scarfed on ebay for under $50. It served its purpose, but the sliders were scratchy and the pushbuttons weren't staying latched - not to mention what I was missing in clarity and soundstage.

Here's what I am listening with now

Source: 1977 Technics SL-1900 (owned since new) w/AT440Mla - on second stylus - no MC yet, still too pricey for me.

Pre: ARC SP-4 with MC factory upgrade

Amp: Hafler 9180 from Audiogon

Speakers: Vandersteen 2C - bought local from original owner - he owns an antique store and he is a complete audio junkie - he had those Vandies in his store playing Muddy Waters - Folk Singer - I didn't know what was going on and I was looking to see Willie Dixon with a stand up bass sitting in the corner.

Anyway - this was supposed to be my sub $1000 system, but the SP-4 blew the budget and hopefully will be reliable for few years so I can get around to a MC cartridge or maybe different amp. Last night I spun up Patti Smith's version of Gimme Shelter and those guitar sirens were haunting. I am a rock and blues listener, so guitar is what I am always listening for and wow, I can hear every single bit of fuzz, bend, attack, bite and rasp on my favorite guitar works. My old friends - Muddy, Buddy Jimi, Jimmy, Jack, Neil, Marissa and Mark have all moved in and practice in my listening space now - and hey, they are not eating much - just a new stylus every 1500 hours. It's a short life, I will enjoy the moments so much more.

Tjaco, Did you ever get an MC cartridge paired with your SP-4? I currently have an SP-4 and am using a Grado MM Cartridge and thinking of upgrading to an MC. I am curious about your experience with an MC on that preamp.