Interesting resistors ya got there!!!
View attachment 124298
View attachment 124299
>> PCB mounting holes need to be "isolated/non-plated thru" holes
as having multiple mounting hole that are all connected to your GND
"Copper Pour" all connecting to multiple points on your chassis will
more than likely create a "Ground-Loop" somewhere. Unless, of course,
you are using Nylon standoffs!!!.....
View attachment 124300
>> I realize that your current designs are "more than dead
quiet" and all that, but.....this is an area that generally creates
problems which can be easily avoided just by using a simple
PCB-design technique. I once worked at AMPEX in Redwood City, CA
in their "PCB Design Department" back in 1980. My 2-cents.....
>> In related news.....should you ever need any AMPEX chassis
or other sheet-metal designs/replications, I can assist you in
that department.
/
I have put shrinkwrap on the screws to avoid ground loops. Star ground to the input connector is how I roll.Interesting resistors ya got there!!!
View attachment 124298
View attachment 124299
>> PCB mounting holes need to be "isolated/non-plated thru" holes
as having multiple mounting hole that are all connected to your GND
"Copper Pour" all connecting to multiple points on your chassis will
more than likely create a "Ground-Loop" somewhere. Unless, of course,
you are using Nylon standoffs!!!.....
View attachment 124300
>> I realize that your current designs are "more than dead
quiet" and all that, but.....this is an area that generally creates
problems which can be easily avoided just by using a simple
PCB-design technique. I once worked at AMPEX in Redwood City, CA
in their "PCB Design Department" back in 1980. My 2-cents.....
>> In related news.....should you ever need any AMPEX chassis
or other sheet-metal designs/replications, I can assist you in
that department.
/
I'm interested in a cover for my 351. It was missing when I got it.Interesting resistors ya got there!!!
View attachment 124298
View attachment 124299
>> PCB mounting holes need to be "isolated/non-plated thru" holes
as having multiple mounting hole that are all connected to your GND
"Copper Pour" all connecting to multiple points on your chassis will
more than likely create a "Ground-Loop" somewhere. Unless, of course,
you are using Nylon standoffs!!!.....
View attachment 124300
>> I realize that your current designs are "more than dead
quiet" and all that, but.....this is an area that generally creates
problems which can be easily avoided just by using a simple
PCB-design technique. I once worked at AMPEX in Redwood City, CA
in their "PCB Design Department" back in 1980. My 2-cents.....
>> In related news.....should you ever need any AMPEX chassis
or other sheet-metal designs/replications, I can assist you in
that department.
/
Yeah, didn't have a 43k resistor in my stock so I had to improvise. The burnt resistor was from an errant test lead while testing that caused it to burn. Doesn't happen when running quiescent.
I have made new upgrade circuit boards for the Ampex 351. They have 20db better signal to noise and I will make them available soon. They are drop in replacements for the original boards. 70db of signal to noise, .5% distortion. They really sound great. They also provide phantom power to microphones.
Ignore the burnt resistor. I did that with an errant test lead to ground. The resistor is fine in normal operation. Also I use heat shrink on the mounting screws to avoid ground loops. Star ground to the input XLR connector for very low noise.I have made new upgrade circuit boards for the Ampex 351. They have 20db better signal to noise and I will make them available soon. They are drop in replacements for the original boards. 70db of signal to noise, .5% distortion. They really sound great. They also provide phantom power to microphones.
>> If you can send me even a rough hand-sketch with some fairly accurate mechanical dimensions, I could create a CAD-design of a cover for you. Some photos would also help out as well.I'm interested in a cover for my 351. It was missing when I got it.
I'll see what I can do. I did not get the message for some reason. Maybe it went into spam and I deleted it with the pile of spam messages I get every day.>> If you can send me even a rough hand-sketch with some fairly accurate mechanical dimensions, I could create a CAD-design of a cover for you. Some photos would also help out as well.
Last year, I designed a rack-mount chassis of an RCA Broadcast Equipment Shelf from only the information contained in a 1948 RCA Broadcast Equipment brochure!!! The brochure contained just the basic dimensions and a series of old photos of this unit. My new 3D CAD-designed version looked pretty cool!!!
Also, I sent you a detailed and lengthy message over this past weekend at your personal webpage. You might wanna check that out.
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Sorry for late reply. I always transported mine in my own vehicle. If expecting air travel, I would have a real transport flight case made with a few inches of foam surrounding the Ampex case. These are not light weight and with today's horrible freight handlers, I would plan for worst case handling scenario.Thanks Jen. Yes, the 350 series is superior to the 600 series. I looked at the 351 in road cases but the first barrier was checking the equipment on flights. Did you put yours on numerous flights in checked baggage and did they survive ok? What did you have to check out and possibly adjust after a flight to make sure they performed as well as they did before the plane ride?
I used to lug around a CROWN SX-722 for doing "LIVE" recordings back during the 1970's!!!My mentor did classical recordings for an American label in Europe in the 1960’s. They were done on Ampex 300’s. He took two 300’s with him…
A mentor who was dedicated to quality sound. Your comment reminds me of an article I read in my teen years (mid to late 1960s) in a broadcast engineering magazine about Bella Bartok's son, Peter, and his recording activities.My mentor did classical recordings for an American label in Europe in the 1960’s. They were done on Ampex 300’s. He took two 300’s with him…
I remember reading about those and wanting one.I used to lug around a CROWN SX-722 for doing "LIVE" recordings back during the 1970's!!!
[I used to lug around a CROWN SX-722 for doing "LIVE" recordings back during the 1970's!!!] -- At the time that I bought my CROWN SX-722, for the price, I -- COULD -- have bought 3 ReVox A-77's!!! What a choice, huh???I remember reading about those and wanting one.
Thanks for the great story! That was a time when some businesses treated people as individuals and valued customers. The wise ones understood that young people of the day were more than current customers, we were their potential future customers.[I used to lug around a CROWN SX-722 for doing "LIVE" recordings back during the 1970's!!!] -- At the time that I bought my CROWN SX-722, for the price, I -- COULD -- have bought 3 ReVox A-77's!!! What a choice, huh???
Not only that, but.....during that time while growing up in Indianapolis, IN and knowing that Elkhart, IN was about 2-1/2 hours north up on Route 31 of Indy, I was able to drive up to the CROWN facility and I bought my tape deck directly from CROWN themself!!! WOW!!! Their finance department and I worked out a payment plan (with no interest) and I religiously made sure that I made my payments to CROWN every month!!! Doing something like that was completely UNHEARD OF back then, let alone even today!!! But, I was so grateful that such a company as CROWN would not only directly sell me a tape deck, but also -- trusted -- this "young kid" (I was around 20-years old then) enough to make all of the payments and not skip out on them.....that I have always had a special place for the company in my heart. I was devastated to learn of their sad closing and going out-of-business (In June, 2018, Harman International shut down the Crown International headquarters in Elkhart, IN and moved manufacturing to Mexico in an effort to consolidate resources).
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Until very recently, David Dintenfass had a voiceover studio in Seattle with an Ampex 300-series deck as an option.I am looking for recording studios with an Ampex 350/351 to record spoken word. Ideally, they would be stereo decks but a mono machine could suffice. We will likely need studios in New York, Los Angeles, Chicago, and central/eastern Europe (Germany, Poland, the Baltics, or Scandinavia). I found one near London. The studios will be needed in 6-12 months for a documentary film, so I am checking now if they exist. If not, I'll pursue a plan B to get this late 1940s/1950s sound.
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