3 Ampex 351 local bargain - missing amplifiers..shoul'd i?

IronWine

Member
Hey there reel people!
A local old man is getting rid of 3 Ampex 351 (one is mono, two are stereo) that are sitting in his garage. he wants for the whole lot 250$. there's extra 150$ for shipping and handling, as it sits at -1 floor and about 45 min drive from my place.

i am having serious doubts tho as they all miss the electronics. putting aside transport condition and such. what will be the options of replacment amplifiers for those tape recorders? to put it otherwise, what are my options of connecting those machines to let's say, a mixer or other preamp, and not to the orginal one? my major concern is about the interconnections for the different heads, and the transport connection - picture of the back panel of the *missing* preamplifier is attached .
I can see that only Inovonics made an official replacment for the 351's original electronics, but they are rare as the original.

they came actually from the national radio auction. so i assume they were regularly maintained, but might have some mileage on them..therefor buying 3 of them woul'd make a good source for spare parts.

Important to say that i am looking to buy those as a part of my final year sound diploma project, under the guidance of my electronics teacher. the final goal is to a create a working example of this fine machine and to thoroughly understand the proccess of magnetic recording & electronics. therefore, a poor condition machine is not nessecerly a drawback , i am not expecting to get a 100% working unit to put in my studio.


cheer guys !

attached:
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If I were you I would run. Getting a clapped out 351 carcass running right is not for the faint of heart. You cannot connect the tape heads to modern low impedance amplifier electronics...the tube stuff was low impedance. So you are then stuck trying to:

A. Find working 351 electronics (EXPENSIVE)
B. Find matching clapped out left for dead 351 electronics and get them working (EXPENSIVE, and complicated...there is a raft of pitfalls and caveats to refurbishing 351 electronics, and they are more dangerous to work on because of the high voltage)
C. Find Innovonics replacement electronics (rare, likely in need of work, and then you STILL have to get the transport working right which is highly likely to be expensive and time consuming)

If this project could count as ALL of your final year project then maybe it would be worth it, but that’s the commitment level you are getting into if you want to take this on.

My vote: run.

If you are interested in a classic broadcast/recording industry tape machine that has a broader base of support, is easier to find, is easier to get going, then why not an Ampex 440? Or just get on Craigslist or eBay and find anything local in a 1/4” halftrack that is running. Is it necessary to find something that needs work?

I’ve taken on some stupid ugly projects and I wouldn’t get into an Ampex 351 project like that.
 
Thanks for you input sweetbeats. i'm reading it now with the 3 machines standing by me :D
you had some realy good points. those machines are 1950' beasts with heavy electronics and 100 pounds cases. getting those without amps was my red line. it turned out that the missing amps deal was a miscommunication between me and seller. he's an old guy and to really understand him properly i had to drive back there again and understand fully what the deal includes. i was thrilled to find out that the sought-after amps are there and he only meant that some power amps he used are not included.

And here's the family:

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dirty, heavey, beaten up wooden cases, but generally good condition and ofcourse the beautiful amps are present ! atleast 3 of them. that means i can run at least a stereo machine and also the mono one.

Truth it, i think that this project gonna serve a good cause and i'm excited to have the honor to even touch those machines. getting even one of them to work is enough for me truthfully.
 
Cool. I'll be interested to know how that goes. I was going to suggest that since the schematics are available, designing some PCBs and building your own clone amplifiers would be possible, albeit a seriously big project. (There was a guy who built new electronics for Brenell machines so it's not entirely an untrodden path). Good to see that the electronics are all present and (hopefully) correct.
 
Well that’s cool some electronics modules are there. Good deal.

I can tell the machines stir your emotions so don’t let me be a discouragement. I won’t be of much help since I don’t know any of the 300 series machines, nor do I have any experience with the tube stuff. Presumably the electronics and transports are complete so that right there is a huge good start. If you are not already a member of the Ampex List (an old-school email listserv group that includes some electronics geniuses) you will want to join as soon as you can and scour the archives for AG-351 related stuff. Read, read, and read some more. The link seems to be down at the moment but it is www.recordist.com. If you didn’t get manuals with the machines they should be readily available in a number of places on the interwebs.

Again, not a project I would touch...it’s a big one...but I’ve gotten tangled in some projects many would say “don’t go there”, but I did it anyway because something sparked me about the gear. Granted the projects are ongoing after a decade so far :D, but I can’t say at the moment I regret taking them on. That’s not always been the case. :o

Best wishes, congratulations, enjoy, and keep us posted. I’m sure we will help as much as we can here and the references above will probably be your best resource...I couldn’t have done anything with my Ampex MM-1000 without the folks and info on the Ampex List.
 
Thank you both guys!
YES, i'd love to keep you all posted. it's a year long project so it might be awhile untill true achivments will be made tho.
in the meanwhile, a photo i like to call "Erase head and a bug". also, some cleaning agent tests regarding getting that face plate all shiny again.IMG_2575.jpgIMG_2569.jpg
 
This is fun. :)

What did you use to clean the faceplate? I have lots of brushed stainless to polish eventually with my MM-1000.
 
26/04

hey there ya'll
sorry for the long delay..duo to the fact that it is my college studies final project it took a hell of lot more time then i thought to get start with it, April is actually the first month they are able to approve projects ideas. and so mine has been firmly approved and the two stereo machines transports made their way to the electronics lab at my school .

as for the polish sweetbeats, i used Peek multi-purpose paste for the test. it seems to do the job. Early next week i'm gonna take apart the whole transport and polish the faceplate to look like it's out of Redwood factory in 58' :cool:

as for today, i have disassembley the "Control circuit box" as the manual states, and it is in remarkable condition according to my electronics teacher. i was quit weary at first duo to the fact that the machines were storaged in a house like 300 meters from the beach. no corrosion what so ever!

i was able to find tho a burned resistor (R506) bridging pin 5 of the remote control and pin 6 of the control section. (probably the remote control shorted out at some point). intresting to note, that the connector for the remote control is acting as a jumper and even if the remote is not in use, it is cruicial still.

in the photos:
- control circuit box dissassembled
- the late R506.
-some more close ups of the (first machine) transport
-and at last some more photos of that cold january salvage day

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jjjj.jpg

more updates soon!
 
Brave man! Don't know the machines of course but do have a bit of valve ken so might be of a little bit of help there.

Those conns' look like "Jones Plugs"? Takes me back the Church organ factory where dad was woodshop foreman!

Can I assume you are going to replace all those capacitors? The blue one look a little like 'our' Wimas (shorting ***t in Grundigs) and the black jobs Hunts? They are No 'King good either!

Sweets' mentioned "High Voltage". I do hope you are aware? There are no old, bold valve techs.

Dave.
 
Brave man! Don't know the machines of course but do have a bit of valve ken so might be of a little bit of help there.

Those conns' look like "Jones Plugs"? Takes me back the Church organ factory where dad was woodshop foreman!

Can I assume you are going to replace all those capacitors? The blue one look a little like 'our' Wimas (shorting ***t in Grundigs) and the black jobs Hunts? They are No 'King good either!

Sweets' mentioned "High Voltage". I do hope you are aware? There are no old, bold valve techs.

Dave.

heya Dave

funny you have mentioned those blue caps..polypropylene caps if i am not mistaken, i have actually been adviced that those live forever! every cap weill be checked anyway. the goal of the project is to bring back this machine to manufacture specs , thrilling job!

yup exactly Jones plugs. sturdy as a horseshoe.

i am fully aware of valve tech risks, and rather get old then bold ha

IMG-20180426-WA0005.jpeg
 
heya Dave

funny you have mentioned those blue caps..polypropylene caps if i am not mistaken, i have actually been adviced that those live forever! every cap weill be checked anyway. the goal of the project is to bring back this machine to manufacture specs , thrilling job!

yup exactly Jones plugs. sturdy as a horseshoe.

i am fully aware of valve tech risks, and rather get old then bold ha

View attachment 102471


Yes, some caps do have a very good reputation. Mullard "Mustards" were used here in TVs and audio and I never had one fail in 50 years of servicing. They have gained a bit of a 'cache' in the guitar world for 'A' sound? All complete bollox IMO!

Volts? Yes, Live long and Prosper.

Dave.
 
Quick question:
does anyone around here knows of the AG440 series preamps can be hooked with the older 351 transports?
have a chance to grab a pair for 200$.
 
A quick Google tells me those pres use a couple of transistors and v cheap transformer and it is suggested that Behringer mixer would be better!

Dave.
 
Dave, the AG-440 electronics are discrete class-A high-amplitude unipolar powered line amps...not sure what you were reading...the plugin octal socket mic transformer options were nothing to write home about, but I would NEVER choose a Behringer line amp over AG-440 electronics...that is the most absurd thing I’ve read so far this year. And yes I’ve used both.

Anyway, to answer your question IronWine, short answer: no.

The AG-440 electronics will not work with the AG-35x heads...the head coil impedances are too different between the two machines. Plus you run into a mess trying to integrate the mode switching functions between the two families of devices.
 
Dave, the AG-440 electronics are discrete class-A high-amplitude unipolar powered line amps...not sure what you were reading...the plugin octal socket mic transformer options were nothing to write home about, but I would NEVER choose a Behringer line amp over AG-440 electronics...that is the most absurd thing I’ve read so far this year. And yes I’ve used both.

Anyway, to answer your question IronWine, short answer: no.

The AG-440 electronics will not work with the AG-35x heads...the head coil impedances are too different between the two machines. Plus you run into a mess trying to integrate the mode switching functions between the two families of devices.

Sorry, I saw "pre amp" and thought "microphone" Then Google led me to a comment that there are some rubbish mic pres about and I wanted to warn the OP not to waste his money. Re the 'Behringer', just passing on a flippant remark from the same source.

All academic now anyway...

Dave.
 
Thank you sweetbeats for your input. yup, it seems like the differences of heads impedance killed the hybrid machine idea. i might just grab them anyway.

As the project going on, the whole transport is now disassembled.
The faceplate is now all shiny and clean. there are some spots that still need a rougher method of cleaning, but Peek's all-purpose solution had exceeded my expectations.
The heads assembly still needs some work. it's wires also need to be inspected carefully, but man those amphenol connectors are timeless!
I believe the heads are in fair condition . the other machine might become a source for parts if needed tho


Here's some pictures of the recent sessions.
 

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work in progress!
over the past two weeks i had 3 sessions . did mainly deep cleaning for the different parts.

this is actually how the faceplate looked at the first place:
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so yes i reckon most of the 50 years old debris is gone now.

also these nameless parts are getting refurbished:
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the motors :
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and the this bulky 110v-220v 500W UTC transformator will get a new AC cord:

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up untill now i was focusing on getting the transport section as clean as i can. i kinda like this porject is getting done step by step, as this is my first true encounter with refurbishing proffesional tape machines.
up next, I will try the engage the motors and see if they run smooth as they should!also will be checking for any shorts in the control circuits box.
 
This is great to read about. If only I had one of those.. a working one that is, I doubt I could repair it.
 
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