Driving a Crystal Cutting Head With an External Amplifier

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megrimm
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Joined: Fri Nov 23, 2012 7:18 pm

Driving a Crystal Cutting Head With an External Amplifier

Post: # 22268Unread post megrimm
Fri Dec 21, 2012 11:14 pm

So i have a recordio a-87. it has a astatic x26 cutting head. the internal amplifier does not work (yet at least). I ran a line from the 1/4" headphones jack of my Kenwood receiver for a test, to the astatic x26. I could clearly, although faintly, hear sound.

I thought... good news!!!

So I tried a test cut on the back of a CDR. It seemed to cut fine but when played back on my record player... no sound.

So i read for a crystal head i needed a "high impedance" amplifier no? What is that exactly? is there a way to get a recording from any home equipment? what do i need to do?

i am assuming running a line from the headphone jack to the cutting head and cranking the volume is not going to work for me.

i am also assuming the crystal head is OK because i can hear sound coming from it. Although i might just be wrong.

....and am just learning, obviously.

m

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Angus McCarthy
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Location: Bloomsburg, PA, USA

Post: # 22273Unread post Angus McCarthy
Sat Dec 22, 2012 2:59 pm

You need to look for an amplifier with (IIRC) 500ohm speaker outputs, which are not easy to find these days. The average home amplifier will use either 16, 8, or even 4 ohm outputs. A headphone jack has its signal further attenuated so as not to blow out the phones - that is useless as a driver for a cutting head. You will want to directly connect the speaker outputs to whatever cutting head you are using - crystal or magnetic. You might get a result by cranking your amp, but that runs the risk of damaging the amplifier itself.

You may get sound from the crystal if it hasn't dried out completely, but it would undoubtedly increase the clarity if you had it replaced with a fresh one.

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Angus McCarthy
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Location: Bloomsburg, PA, USA

Post: # 22274Unread post Angus McCarthy
Sat Dec 22, 2012 3:01 pm

*double post* :oops:

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megrimm
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Post: # 22276Unread post megrimm
Sat Dec 22, 2012 5:46 pm

thanks for the tips! at the moment im looking for something to drive it i have around the house. i will give it a go with cranking the home kenwood with te cutter head attached to the speaker output...

maybe you know of a 500 ohm example? i see things like this that output high impedance:

http://www.ebay.com/itm/SMSL-sApIII-High-impedance-Professional-TUBE-headphone-amplifier-BB-OPA2604-/290797739690?pt=US_Home_Audio_Amplifiers_Preamps&hash=item43b4e55eaa

maybe this line converter:

http://www.ebay.com/itm/170962351326?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649

OR maybe a guitar amplifier output?

thanks!
m

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emorritt
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Joined: Thu Nov 09, 2006 2:03 pm
Location: Tennessee

Post: # 22278Unread post emorritt
Sat Dec 22, 2012 7:44 pm

An X-26 is looking for around 180VRMS to work properly. You might be able to make it "sound" with a lower wattage amp turned up all the way, but to get the proper level to drive the stylus to make a viable groove, you need either direct plate drive or a transformer to convert the low voltage output to a high voltage output.

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