Moving Coil Phono Step Up Transformer Box For Altec/Peerless 4722 Or 4665 MC SUT
Item History & Price
| Reference Number: Avaluer:29720670 | 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 or 4665 transformers, or other transformers with pin out identical to the 4722.
You can see this box has a gain switch marked "hi" and "lo" which 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. The box is wired so that when used with 4665's the primaries are in parallel, for what's shown on 4665 ...spec sheets as 150 ohm and 50 ohm wirings. Because the 4665 has slightly higher step up ratios (about 23 and 46 times) than the 4722, the actual loads your cartridge will see in these positions are about 90 ohms in the low gain position, and about 23 ohms in the high gain position. If you intend to use the box with 4665's and would like access to the lower gain/higher impedance wiring options, just let me know. I'll be happy to wire it to suit your needs.
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.
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.
This is a newly made box using Belton 8 pin sockets and gold plated Switchcraft jacks.
I've included a photo showing how the 4665's fit on the box, but no transformers are included with this auction.
You can see this box has a gain switch marked "hi" and "lo" which 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. The box is wired so that when used with 4665's the primaries are in parallel, for what's shown on 4665 ...spec sheets as 150 ohm and 50 ohm wirings. Because the 4665 has slightly higher step up ratios (about 23 and 46 times) than the 4722, the actual loads your cartridge will see in these positions are about 90 ohms in the low gain position, and about 23 ohms in the high gain position. If you intend to use the box with 4665's and would like access to the lower gain/higher impedance wiring options, just let me know. I'll be happy to wire it to suit your needs.
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.
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.
This is a newly made box using Belton 8 pin sockets and gold plated Switchcraft jacks.
I've included a photo showing how the 4665's fit on the box, but no transformers are included with this auction.
