Strong 4 ohm Receiver

[wdrazek]

Hello,

Just picked up a pair of smaller Advents which are 4 ohm. Posted in the Advent forum and got a few comments about staying away from Marantz and Sansui's. Reading late 70's Marantz literature they recommend avoiding early SS because the designs used limited damping factors and 4 ohm power. I also noticed that they did not appear to even quote 4 ohm power ratings until '77 or so.

I have the following questions:

Is there a particular brand that provides better 4 ohm performance than the other main players (Marantz, Pioneer, Yamaha, Kenwood, Sansui)?

Were late 70's receivers superior to earlier efforts at driving low impedance loads?

Is it better still to focus on later designs like NAD's from the 80's or even more modern equipment?

Thanks for all of your replies.

 

[yrly]

The later 70s Fisher RS-1060 can drive a 4 ohm load and run cool doing it, seems to strain it little if any. Of course they're somewhat rare so finding one isn't easy.

 

[westend]

I've had Sansui, Marantz, and Kenwood driving Advents with no problem. The more vintage receivers and amps (circa '70's) seem to handle lower impedance better than, say, black-stuff from the 80's. That is maybe opposite from what you have heard but is my experience.
I have had a Marantz 2270 driving Klipsch KG2's (a four ohm rated load) and, through the B channel, a pair of Heil AMT's (3 ohm load). Sure, I didn't drive them to near-concert levels but all was good with the Marantz. I've also used a Kenwood 8100 to drive two sets of speakers at dance-hall volume and the Kenwood didn't break a sweat at 3/4 volume.
I wouldn't be worried about driving the Advents with most of the more popular brands if you are using a receiver that is able to push more than 40 w.. The power supplies and output sections of these vintage products are pretty robust and will handle a small set of speakers, even at a 4 ohm rating. If you are very concerned about ruining your gear by trying this, you could place a resistor in series with your speaker wire to present the receiver or amp with a higher impedance. I don't think it's necesary, though. Good luck with the Advent's.

 

[javelin79]

The early pioneer recievers from like the sx-850 up are okay at 4 ohm but the QX949 or QX949a will run a 4 ohm load no prob. I had 4 acoustic Research AR-11's running with it and had no probs at all. The QX949's are 50wpc in quad and like 80 in 2 channel.....either way they have awesome sounding amplifier sections in them.

 

[Brian]

The one receiver that I found can run The Smaller Advents equally as well as the originals is the Radio Shack STA-2250. It was their 2nd digital tuner receiver and a beast. I'm not into RS but bout it at a thrift shop after moving it and being amazed at the weight. Figured for the $5 I had at worst a door stop. I was amazed at the amp though the tuner has a typical digital tuner sound. I tried it with the SAs and it was an eyeopener. So I decided to do a A-B comparison with the original Advents. The design criteria for them was they will sound the same. However b/c few amps are as stable into below 4 ohms as at 8, the reality is that few times will they off SS amps. The RS passed the test with flying colors. On researching the unit I read a review where the unit tested more stable into 2 ohm loads than amps that were advertised as stable into 2 ohm loads.

Besides passing the test the speakers really sounded good off the amp. The tuners on these are all but not repairable as parts available is non existent for a number of parts. The amp inputs are also on top of the boards and it would not be hard to mod the unit to allow for a preamp output and power amp input. These do not go for much and are not the hot sought after RS receivers as they are digital. The 1st ditital receiver, the STA-2200 is supposed to have an even better amp, think it is mos-fet. At the time I got mine the 2250 was going on the auction site for something in the range of about $30 in working condition. I've not followed pricing so do not know aobut it today.

My recommendation from my experience.

Oh, your concern is real. If the amp is not stable into 4 ohms and below for the SA, the amps will eventually cook or worse even if not driving them hard. Only a question of time. Any design not working within its parameters will not live as long and the results can be very nasty. Just my $.02 on that subject.

 

[fwardell]

My Dynaco set-up (PAT-4, FM-5 & ST-120) does a nice job with my 4-ohm AR-3As. I've heard that it was designed with these ARs in mind.