Moving Coil Phono Step Up Transformer Box For Altec/Peerless 4722 Or 4665 MCSUT
Item History & Price
| Reference Number: Avaluer:17819672 | Country/Region of Manufacture: United States |
| Country//Region of Manufacture: United States |
Here's an empty moving coil step up transformer box for use with your Altec Peerless 4722 transformers, or other transformers with pin out identical to the 4722. I've modified the spacing and orientation of the sockets a bit from the style I've been selling up until now so that Peerless 4665 transformers can also physically fit and work with it (see more info below). This is an engraved cast aluminum box using high quality Belton octal sockets.
Gain:You can see this box has a ...gain switch marked "hi" and "lo". This switch selects between the 4722's 38 and 150 ohm primary taps respectively, giving about 18 times step up for low gain, and 36 times for high gain. This wiring will also work with the 4665's equivalent primary taps, but because of the 4665's slightly higher step up ratios (about 23 and 46 times), the actual loads your cartridge will see are about 90 ohms in the low gain position, and about 23 ohms in the high gain position. Of course the 4665 has a couple of lower ratio primary impedances that aren't available with the 4722, and depending on the cartridge you're using, these might be preferable for you. I'm happy to wire the box for a higher pair of impedances at your request and for no extra charge, however any other wiring will make the box no longer compatible with 4722 transformers. The current 90 and 23 ohm wiring is the only one that allows the box to be fully functional with both transformer types.
Ground switch:This box is wired with the three grounds (left audio, right audio and chassis earth) normally kept separate in order to avoid potential ground loops. However, there's a 3 position ground switch that can tie them together to make wiring easier and give you a few choices for dealing with potential hum problems. It's main purpose is to select how the aluminum box is to be grounded for shielding.
1) In the "L" position, the box is connected to the left channel audio ground. In this position you can attach your turntable ground wire to the ground lug on the SUT, and shouldn't have to run a separate wire from the SUT to your preamp. This provides the easiest way to wire the box, and usually works fine.
2) In middle position the three grounds are kept completely separate. In this position the box must be externally grounded to chassis earth, so run a separate wire from the SUT ground lug to your phono preamp ground lug. Once that wire has been run, you can attach your turntable ground wire to either the SUT or your phono pre. This position can often give lowest possible noise, but does require the extra ground wire.
3) In the "L+R" position the box is connected to both the left and right audio grounds, meaning all 3 grounds are tied together. This position can be useful if you're using certain cable sets that only have one of the channel shields attached at both sides. This is a rare problem, but I've heard from enough people who've run into it that I decided to include a ground position on the box that helps deal with it. In this position you shouldn't have to run a separate ground wire between the SUT and your preamp. In general if you don't want to run a separate ground wire, the "L" position is the best one to use, since "L+R" will technically create a ground loop when using standard wired RCA cables.
That's a fair amount of information, but in general you don't really have to worry too much about what the ground switch is doing. Just wire up the box however you like and put the switch in whatever position seems to give you the lowest noise.
I've included a photo showing how the 4665's fit on the box, but of course no transformers are included with this auction. I don't currently have any 4722's or 4665's available for sale, but I have a couple of different pin compatible transformers in my other auctions, as well as a box identical to this but including Beyer plug in transformers, so if you need transformers as well, be sure to take a look at those.
Gain:You can see this box has a ...gain switch marked "hi" and "lo". This switch selects between the 4722's 38 and 150 ohm primary taps respectively, giving about 18 times step up for low gain, and 36 times for high gain. This wiring will also work with the 4665's equivalent primary taps, but because of the 4665's slightly higher step up ratios (about 23 and 46 times), the actual loads your cartridge will see are about 90 ohms in the low gain position, and about 23 ohms in the high gain position. Of course the 4665 has a couple of lower ratio primary impedances that aren't available with the 4722, and depending on the cartridge you're using, these might be preferable for you. I'm happy to wire the box for a higher pair of impedances at your request and for no extra charge, however any other wiring will make the box no longer compatible with 4722 transformers. The current 90 and 23 ohm wiring is the only one that allows the box to be fully functional with both transformer types.
Ground switch:This box is wired with the three grounds (left audio, right audio and chassis earth) normally kept separate in order to avoid potential ground loops. However, there's a 3 position ground switch that can tie them together to make wiring easier and give you a few choices for dealing with potential hum problems. It's main purpose is to select how the aluminum box is to be grounded for shielding.
1) In the "L" position, the box is connected to the left channel audio ground. In this position you can attach your turntable ground wire to the ground lug on the SUT, and shouldn't have to run a separate wire from the SUT to your preamp. This provides the easiest way to wire the box, and usually works fine.
2) In middle position the three grounds are kept completely separate. In this position the box must be externally grounded to chassis earth, so run a separate wire from the SUT ground lug to your phono preamp ground lug. Once that wire has been run, you can attach your turntable ground wire to either the SUT or your phono pre. This position can often give lowest possible noise, but does require the extra ground wire.
3) In the "L+R" position the box is connected to both the left and right audio grounds, meaning all 3 grounds are tied together. This position can be useful if you're using certain cable sets that only have one of the channel shields attached at both sides. This is a rare problem, but I've heard from enough people who've run into it that I decided to include a ground position on the box that helps deal with it. In this position you shouldn't have to run a separate ground wire between the SUT and your preamp. In general if you don't want to run a separate ground wire, the "L" position is the best one to use, since "L+R" will technically create a ground loop when using standard wired RCA cables.
That's a fair amount of information, but in general you don't really have to worry too much about what the ground switch is doing. Just wire up the box however you like and put the switch in whatever position seems to give you the lowest noise.
I've included a photo showing how the 4665's fit on the box, but of course no transformers are included with this auction. I don't currently have any 4722's or 4665's available for sale, but I have a couple of different pin compatible transformers in my other auctions, as well as a box identical to this but including Beyer plug in transformers, so if you need transformers as well, be sure to take a look at those.
