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PostPosted: 23 Feb 2013, 06:57 
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As mentioned on another thread I have a TT which will play 78 records. I have a piezo cartridge which I understand is what 78 records were cut for. I also understand that if you use a piezo cartridge there is no need for any equalisation. You do need a piezo preamp though and this is what I am currently building.

I'm wondering is anyone else is playing 78s? As the project progresses I will make further entries.http://diyaudioprojects.com/Forum/viewtopic.php?f=10&t=4282

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PostPosted: 27 Feb 2013, 01:24 
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Bought a stack of 78s today but most are not good. Hoping to get one two good ones from the pack but nothing yet. If the pot in the preamp is not 25K (in the piezo preamp) you will have big issues. I have a 50K pot and put a 47K resistor across it and that will work. My preamp is still down on gain. I have take another look at what is wrong. The first one I built had stacks of gain. It could even be the chip.

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PostPosted: 06 Oct 2013, 22:16 
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I have finally got my 78 system working well. I tried a couple of different piezo preamp for my piezo Ronette cartridge but was unsatisfied with the performance. I ordered and fitted a new 78 stylus for $17. Plus bought a whole bunch of better looking 78s.

The new piezo chip based preamp and (especially) the new stylus has made a massive improvement. I have now been listening to some great sounding classical 78s. There is no bass from 125 Hz and down. I only just realised the reason for this is that old TTs would have had too much rumbled to play any lower. Also the old tube mics etc wold distort down this end.

The TT is a modern rebadged Audio Technica direct drive with 78 capabilities. This TT with a new Garrott K2 sounds excellent for normal LPs. The Garrott Brothers Cartridges are way under rated. Is it because they are Australian? I think the K2 cost about $350 and is exceptional value at that price.

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PostPosted: 07 Oct 2013, 13:45 
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Hi Mark, Many of the crystal and ceramic cartridges were designed to work into high impedances. Typically 500K to 2meg. The equalization was often a simple RC arrangement that tended to cut the highs above about 1000 HZ. There actually were some rather good ones. Electro Voice, and Astatic had some that even came with diamond needles. The sound is not up to the standards we now expect, but was often pretty good.

Good listening
Bruce

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PostPosted: 07 Oct 2013, 17:15 
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A very knowledgeable friend told me that 78s were cut to run with piezo carts and required no equalisation. After saying that being able to reduce the treble\surface noise would be useful.

The last piezo preamp I built had just that. Like a treble control.

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PostPosted: 07 Oct 2013, 22:13 
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Hi Mark, that is a typical thing to do as there was little consistency between manufacturers on how they recorded the disks. Since most of the disks had little content below 200HZ and little above say 2500 using filters (simple tone controls) will probably give you the best sound. S/N was rather poor by present standards. On one that has been played it most likely will not exceed 30 db on a good day. I believe that GE made some Variable Reluctance cartridges that worked on 78s. It sounds like a fun project.

Good listening
Bruce

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PostPosted: 08 Oct 2013, 03:51 
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gofar99 wrote:
Hi Mark, that is a typical thing to do as there was little consistency between manufacturers on how they recorded the disks. Since most of the disks had little content below 200HZ and little above say 2500 using filters (simple tone controls) will probably give you the best sound. S/N was rather poor by present standards. On one that has been played it most likely will not exceed 30 db on a good day. I believe that GE made some Variable Reluctance cartridges that worked on 78s. It sounds like a fun project.

Reluctance, trans-reluctunace, Mhos, trans-conductance, trans-mutual don't you just love yesterday?

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PostPosted: 22 Dec 2016, 14:01 
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I don't play 78's,

But here are a few I remember well,
https://www.youtube.com/watch?v=-gPrvoN4c7g
https://www.youtube.com/watch?v=kXheuEUgg8U
https://www.youtube.com/watch?v=IFzM0g2bx6U

The next voice I have always found very special, Mary`s Boy Child (Harry Belafonte).
Childhood memories around the xmas tree.
https://www.youtube.com/watch?v=UZ4FK1uXm_U

I remember many more but..
Here is the circuit diagram from the HMV record player I find the input tube wiring very interesting I believe the N78 was used on aircraft radio gear.

The DH77 is very interesting..

Regards
M. Gregg


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PostPosted: 10 Feb 2017, 15:55 
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LMAO,

I have just watched this, George Fiddler and the PYE black box. :bawling: :D
You have to watch this:
https://www.youtube.com/watch?v=ZqKlayWk61M

The enthusiasm is brilliant..

Regards
M. Gregg

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PostPosted: 10 Feb 2017, 19:20 
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M. Gregg wrote:
LMAO,

I have just watched this, George Fiddler and the PYE black box. :bawling: :D
You have to watch this:
https://www.youtube.com/watch?v=ZqKlayWk61M

The enthusiasm is brilliant..

Regards
M. Gregg


Quite a novel unit.

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