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motorino
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Grampian Preamp Jamaika Style

Post: # 3405Unread post motorino
Sun Aug 31, 2008 2:18 pm

i received all the components

NOS NE5534 (better than chinese news), Wima caps, precision metal film resistors, and cermet Pots

I have components for made 2 preamps, first i made the original with balanced output, after i believe made other one...

I have a old filter in a good box, i remove one, use the power supply and i added a Ant (Neumann) vu-meter

Next week the test!

Image
Image

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Steve E.
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Post: # 3406Unread post Steve E.
Sun Aug 31, 2008 7:59 pm

I look forward to it!

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flozki
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Post: # 3884Unread post flozki
Thu Nov 27, 2008 4:20 am

any updates yet?
does someone cut already with this type of preamp?

flo

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emorritt
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Post: # 3889Unread post emorritt
Sat Nov 29, 2008 2:01 pm

Yes I built from the original schematic you posted Flo and it works great. Just a little too much high end - I'm trying to change the resistor/cap arrangement around the first three amp chips, maybe eliminate the 50pf/10K and change the 30pf value on A-1 and possibly try using your other RIAA circuit in place of the C/R network on A-4. The box I built has a common connector going to the cutting head, and a terminal strip that connects the preamp circuit to my Presto 92A amp. Cut several disks for customers with the box as-is and no complaints. Sounds very good.

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motorino
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Post: # 4575Unread post motorino
Sat Mar 14, 2009 5:23 am

hello guys!

I have been confused with this project for some reasons... but now we return to.

decided change 1 U box, for a better 3 U, and put inside all the necessary, 3 different power supplys, preamp, feedback monitor, amp, current meter etc.

have a friend who is designing the front, is a very good graffiter :twisted:

Some pics about

Image
Image


One question, ALL the opamps NEED the bypass capacitor to prevent oscillations if use the NE5534

Other question for me its the design for drive current meter ( I send you the ask to your mail Flo)



beautiful day for all yours, and me ;)

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emorritt
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Post: # 4578Unread post emorritt
Sat Mar 14, 2009 12:17 pm

Mine ain't glamorous but it's in a 2U box (only because of the transformer) and works great.

Image

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motorino
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Post: # 4579Unread post motorino
Sat Mar 14, 2009 1:06 pm

glamorous? 8) jajajaj ;)

some improvements in the schematics, and have one question more about the feedback, for the feedback monitor: what time constants need for a true monitoring? the reproduction riaa standart time constant? and for the feedback mixer? a passive filter circuit with gain amplifier? a 24 dbs linkwitz-riley lpf? what type of filter works better with the grampian caracteristics? uuuf

we need help

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emorritt
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Post: # 4580Unread post emorritt
Sat Mar 14, 2009 2:28 pm

I haven't got a feedback monitor hooked up on the mono system, only use the FB monitoring with my Westrex 1574's for the stereo system. For the Grampian mono system I do whatever tweeking may be needed (usually not much) then do a test cut and if it flies, it gets cut.

Image

The head mount is one that Len Horowitz built for me and it works beautifully for mounting a Grampian on a Scully - has heater wiring built in and connects just like the Westrex mount.

(I have the coffee habit and my chip vacuum has the baby powder habit... need to send it to rehab with Amy Winehouse) :lol:
Last edited by emorritt on Sat Apr 04, 2009 5:34 pm, edited 1 time in total.

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motorino
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Post: # 4581Unread post motorino
Sat Mar 14, 2009 5:16 pm

hey Emorrit! your lathe ITS glamorous!

Len Horowitz has seen the schematics? yours?

and for the cutter current? what you use?

thanks!

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emorritt
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Post: # 4585Unread post emorritt
Mon Mar 16, 2009 10:18 am

Motorino are you talking about the schematic for Flo's feedback box? I've never sent it to him, but I'm sure he's aware of Flo's circuit. Len helped me a LOT with the other lathe/electronics (my stereo system) and he made the cutterhead adapter for the lathe in this photo to mount the Grampian mono head on a Scully. By cutter current I'm assuming you mean my amp; I use a rebuilt Presto 92A to drive the Grampian, but when I built Flo's preamp I added IN/OUT connections to the back of the 2U rack cabinet so there is only one cable running to the cutter (4 wires - 2 drive, 2 feedback) and the other terminal strip connects to the amplifier IN/OUT.

Now that you mention hooking up a monitor to the feedback, you have me thinking. Would be nice to be able to "real-time listen" in the mono suite as well. Hmmmm... where's my soldering iron?? :roll:

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motorino
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Post: # 4611Unread post motorino
Sat Mar 21, 2009 9:15 pm

now + 45 - vdc for amp, + 18 - vdc for preamp and +24 vdc for meter
Image

Image

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tubefan
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Post: # 4794Unread post tubefan
Wed Apr 22, 2009 1:18 am

Nice Scully... Is the 'baby powder habit' the chip sticking to the vacuum tubing? I think Neumann has in the past used a version of the rubber tubing that was doped to be conductive, which would help keep it from sticking to the rubber, natural rubber is a nice insulator. Also may have to do with surface finish of the inside wall of the tubing. Baby powder works though, and is somewhat funnier than the other options ;-).

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emorritt
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Post: # 4795Unread post emorritt
Wed Apr 22, 2009 9:18 am

Yes, it suffers from sticky chip syndrome (sorry) I got the tubing I'm using from a fishing supply place; most of the medical supply houses which might have a different finish on the inside had minimum orders of way too much. I've tried local pharmacies and hospitals but they "don't wanna share"... It was suggested to wash the tubing in a solution of dishwashing liquid which I tried on both this machine and my stereo Scully/Westrex system but the chip still hangs on the inside of the tubing. Most of the time I think it's static related and not just the tackiness of the latex. I've tried using a soft vinyl tubing I found and it works beautifully until the lacquer chip starts reacting with probably the softening agent in the vinyl plastic and turning into a gummy mess. Anyone know of a 'cure all' for this problem?

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drdub
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Post: # 4797Unread post drdub
Wed Apr 22, 2009 11:18 am

try a latex tube - works fine on our neumann vms with laquers and pvc disks.

we bought it at this rubber-shop : www.gummi-winkler.com
(...but i don't think they do mailorder)
satan spins vinyl

*** www.drdub.com ***

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emorritt
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Post: # 4800Unread post emorritt
Wed Apr 22, 2009 3:02 pm

What I have is "latex" but I'm not sure it's pure latex since it came from a fishing lure supply. It's slightly lighter in color than other pieces of latex I have but those may have darkened with age.

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motorino
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Post: # 5001Unread post motorino
Fri May 15, 2009 7:57 am

Finish! :D

Image

But now one problem with the turntable ball bearing noise

The last rectifing-hardened dont work ok, i dissasembled and look small "rails" inside, i believe its assembly problem, the heavy platter go down fast and made a marks in the bearing...

Image


But the dubs sounds good!! Many thanks Flo!!

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mossboss
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Static in Chip Tube

Post: # 5015Unread post mossboss
Sat May 16, 2009 12:24 am

emorritt wrote:What I have is "latex" but I'm not sure it's pure latex since it came from a fishing lure supply. It's slightly lighter in color than other pieces of latex I have but those may have darkened with age.
Hey Emorrit
Here is a fairly easy fix for your hoses If you know any one that uses tin chloride to sensitise acetates so as to make them conductive, than silver them, than make masters and pressing plates? Like a plating shop If so get him to mix you half a litre or so and apply this solution inside your hoses let them dry out and than stick a bit of copper wire at both ends of the mounting points, inside of course and earth them They than become conductive and the problem of static "stiction" dissapears You can do it with the pvc pipes as well as flexible hose as I can see you use both of them them (in the photo) A pre clean with a solvent may be advantageous for a new instalation For an existing hard fixed one as you have, use a very mild detergent say 40 mil of household dishwashing liquid to 10 Litres of water a little warm and pump it through any fixed pipes, rinse it well with clean water a litle warm say about 30-35 C and follow it up with the tin chloride while it is still wet Let it dry before using the system If you start your vacuum system it will dry out in no time
Point: If half or one litre of the tin chloride solution is not going to do it in volume terms to pump through an existing fixed instalation you can dilute it down to the minimum qty required with water in other words keep it as strong as possible and hook up a little water pump to circulate the liquid through the fixed pipe system as long as possible It will still work Of course it may be easier to dismout the pvc pipes treat them and put them back up again, Pvc joiners and glue are pretty cheap
This will work with any type of tubing What we found works very well is good old fashioned petrol hose as it has a very high content of Carbon Black in it which makes it anti static It also helps Petrol stations survive from explosions caused by static electricity sparks If you treat it with a bit of tin chloride first you can forget about for years or until it gets stiff which it does after a while 3-4 odd years
Hope this Helps
Cheers

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emorritt
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Post: # 5020Unread post emorritt
Sat May 16, 2009 12:19 pm

Interesting suggestion and might be worth a try. Thing is, does the stannous chloride actually deposit metal? I thought all it did was activate the surface of the master lacquer and the reaction with it (and probably some other chemicals) and the silver solution was what left the metal deposit. I'm assuming what we're trying to accomplish here is make the inner surface of the tubing at least somewhat conductive to dissipate static.

The machine in the photo above is my mono suite. It's the stereo suite that's got the suction problem. I tried using some emory cloth on the metal parts thinking there might be a slight burr or something catching the chip on it's way behind the lathe to the chip jar. Didn't help. The machine above even with the convoluted path from the suck pipe to the jar doesn't have a sticking problem. Just the other Scully with the stereo setup, and aside from the initial upward sweep from the head the entire path is down past the lifter box, through the lathe table and into the jar. I think another factor might be the heat from the amps (1574 tube amps) vents out along the wall behind the equipment rack and lathe so it probably 'drifts' over and warms up the latex tubes over time. If the A/C is set lower we have a nice high energy bill but my chip doesn't stick. The humidity in Louisiana is an issue as well. I've plated antique phono parts before and will check with supplier to see if they carry stannous chloride and give it a try.

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motorino
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Post: # 5021Unread post motorino
Sat May 16, 2009 9:27 pm

Louisiana! Baton Rouge! Nueva Orleans! :D i remember...

The humity yes, do you have a good earth ground conection in your electric socket? Machine ground? Rack ground? My vacuum system its like
Image

In a camping shop

Dont have any problem with static noise with the latex tube and crystal jar, dont listen or look differences, but normally dont use vacuum system for hold the dub in the platter, use a small bolt for hold in the dub second hole

Put a long cable from your metallic tap water to your turntable, a way to test noise ground conections :wink:

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motorino
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Post: # 5081Unread post motorino
Sat May 23, 2009 12:37 pm

I change the 10k feedback pot for a 47 k pot, my cutterhead have a lot of feedback?when mix the trebles go down a lot, now i can mix better

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