Presto 1D amp spec

[SueDenim]

Hi again guys!

Could anyone suggest a min/max wattage output of an amp to drive a Presto 1D cutting head please?

I think we could assume that the 1D's impedance reads exactly 8 Ohms.

There seems to be quite a few 6N owners on the forum.
How many still use an original 1D as the cutting head?
What amps are your favourites??

Thanks in advance
Sue D. x

[markrob]

Hi,

Almost any amp will work fine with the 1D. As far as I know the 1D was either 15 or 500 ohms impedance. This is marked on the back of the head. You will always read a lower DC resistance than the actual head impedance. So, if you read 8 ohms, I would guess your head is 15 ohms. An amp that can drive 25 - 50 watts should be more than enough for this head. It only takes .6 watts to reach 5.5 cm/sec recorded velocity. Also, this head was designed to be used with a 3 ohm series resisitor (for the 15 ohm version). This establishes the 500 hz turnover of the RIAA curve. You would need to add external EQ to match the 2122 hz high freq turnover and 50 hz low freq turnover points that are also part of the RIAA spec. You can probably get away without the 50 hz EQ.

Mark

[SueDenim]

Thanks Mark.

If I go with a Presto, I will probably ask Gib @ West-Tech to do a full restoration of a 6N which will include the 1D head.
He seems to be of the opinion that he should re-wind the head to an 8 Ohm impedance, which is a little odd if, as you say, it states either 15 or 500 on the casing!

Do 1C heads come with 6N lathes as well?
I'm just wondering whether it has one of these and they are nominally 8 Ohms?!? (just a thought)

Sue D.x

[piaptk]

1d and 1c heads both come with 6ns, but the 1d is a little better.

Gib suggests you rewind to 8 ohms, because it makes it much easier to find an amp that will work for it... you can use any 100W+ stereo amp (though you would need a reverse RIAA curve as Mark suggested. If you have a vintage cutting amp, it might not work with an 8ohm, but you will probably have to recap the whole thing anyway to keep it working right and the tech can easily switch it over to whatever ohmage you ask for. That's what I did with my 88a and 90b.

[markrob]

Hi,

The 1C and 1D are almost the same. The only major differences that I can see are:

1. The 1C came in an 8 ohm version.
2. The damping material on the 1C is different than the 1D.

Otherwise, as far as I can tell, they are the same. In any event, you would need to have the dmaping material replaced. I belive Gib does that as part of the restoration. Re-winding probably makes sense as piaptk stated. When the 1C was in production the low freq turnover was 250hz rather than the current 500hz standard. So, the series resistor was different to make the older turnover point. If you get the head re-done, ask Gib what value, if any, he reccomends.

Mark