Wow, what a blast from the past! When I was in highschool, in the late 50's, I used to hang out on Friday nights at WBAI-FM on top of the Hotel Pierre on 61st Street. On the way there, I'd stop for dinner at a great Irish bar that had hot roastbeef sandwiches on a seeded hard roll with au jus sauce, a few doors down from Harvey Radio on 6th Avenue. It was a major HiFi component store, but always had a full blown consoled Ampex (350 then) in the front window. You could walk through the front showroom area into the back where all the pro gear was housed. It was heaven on earth to me.
Ampex electronics for the best possible sound
- Thread starter RogerD
- Start date
Thanks, 70's never looked so good!
You're still three years younger than my very best friend; and he's full of life, physically and mentally. ...You remind me him.
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Very cool! Thanks for posting. I would have loved to have a store like that in my town. Funny my very first sight of a big RTR was in high school. I walked in to a shop and there sat a Crown CX824....the rest is history. Btw you made me hungry!
Just a update on my Ampex MR70 project. Yesterday I had a meeting with a technician about upgrading the transport control board. What I will do is upgrade the resistors in the logic circuit. This has already been done in two of the transports that are now running. With a local tech I avoid costly shipping and I can supervise,watch and learn. I am excited because now I can have all five of my MR70's fully operational once the head stacks are done. Letting go of such a nice Studer A820 was not easy,but getting 4 MR70's in return I think was a good move. I will have 2 1/4 machines and 3 1/2 machines. I plan on moving one of each to my downstairs system eventually.
Also unpacked the MR70 console and it's in very good condition.A 2 Channel at that and very hard to find. I'll clean it up like new and put the Jack Mullin in it.
Looking at the photo the logic circuit resistors have been swapped out using cement sand type wire wound resistors. the originals have a tendency to short out because of age or a short in the fast mode circuit. These sand types improve reliability greatly. Only problem is Mundorf is the only manufacturer anymore making the needed values. What you use to get for less than a buck a piece,now costs 4.00ea and I'm glad to get them at that.
The upgraded MR70 line amplifiers should be done in about 3 weeks and after listening to the stock ones,these should be pretty special. The MR70's forte is the ability to convey more of the musical performance as far as weight,richness,ambient retrieval,and presence. Comparing my upgraded 350's which are very controlled and very musical,these MR70's should do everything the 350's can and then add the nuvistor sound and I think these will be the best preamps I have. I am hopeful. Most say the MR70 cannot be improved, well there should have been later revisions but that never happened. My goal is to have 2 or 3 of these machines that fulfill the Ampex goal.
I have a MR70 Prototype that is very unique and differs from the production machines. For example the reel escutcheons are metal vs plastic, the transport function switches are different and some mountings for the transport motors are unique also. I only have one electronics that go with this machine,so this restoration if I do choose to restore it will be the last on the list.
I found an image of the 200A recorder circa 1949-1954 with the metal escutcheons like my MR70 prototype transport .It does look real nice with the metal types.
Here is a photo of the one preamp which I have already taken the faceplate off. The main board is white instead of blue,the identification marking for the 3 modules are hand written and the output transformer is not the Triad tuna can but a unidentifiable version.
Well I just remembered I have the 1/4 inch mono headstack , so it is very possible that this prototype is complete. Hmmmmmmmmmm
My preference has always been to the more neutral and natural type of sound reproduction and all the Ampexes have a rich sound and in some cases I consider "fat" but not in a negative highly colored sense. What I have found is that voicing these recorders can be highly rewarding. The sound signature of the rich and musical does not change but what does change is the level of musicality and that is a very worthwhile transition.
Also unpacked the MR70 console and it's in very good condition.A 2 Channel at that and very hard to find. I'll clean it up like new and put the Jack Mullin in it.
Looking at the photo the logic circuit resistors have been swapped out using cement sand type wire wound resistors. the originals have a tendency to short out because of age or a short in the fast mode circuit. These sand types improve reliability greatly. Only problem is Mundorf is the only manufacturer anymore making the needed values. What you use to get for less than a buck a piece,now costs 4.00ea and I'm glad to get them at that.
The upgraded MR70 line amplifiers should be done in about 3 weeks and after listening to the stock ones,these should be pretty special. The MR70's forte is the ability to convey more of the musical performance as far as weight,richness,ambient retrieval,and presence. Comparing my upgraded 350's which are very controlled and very musical,these MR70's should do everything the 350's can and then add the nuvistor sound and I think these will be the best preamps I have. I am hopeful. Most say the MR70 cannot be improved, well there should have been later revisions but that never happened. My goal is to have 2 or 3 of these machines that fulfill the Ampex goal.
I have a MR70 Prototype that is very unique and differs from the production machines. For example the reel escutcheons are metal vs plastic, the transport function switches are different and some mountings for the transport motors are unique also. I only have one electronics that go with this machine,so this restoration if I do choose to restore it will be the last on the list.
I found an image of the 200A recorder circa 1949-1954 with the metal escutcheons like my MR70 prototype transport .It does look real nice with the metal types.
Here is a photo of the one preamp which I have already taken the faceplate off. The main board is white instead of blue,the identification marking for the 3 modules are hand written and the output transformer is not the Triad tuna can but a unidentifiable version.
Well I just remembered I have the 1/4 inch mono headstack , so it is very possible that this prototype is complete. Hmmmmmmmmmm
My preference has always been to the more neutral and natural type of sound reproduction and all the Ampexes have a rich sound and in some cases I consider "fat" but not in a negative highly colored sense. What I have found is that voicing these recorders can be highly rewarding. The sound signature of the rich and musical does not change but what does change is the level of musicality and that is a very worthwhile transition.
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Here is a photo of the MR70 prototype. I have all the parts,plus some special duty reel motors that came with it. This will take time,but I think it will be very nice when done.
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Received my 2nd set of upgraded 440 cards today from Chuck Ziska. Chuck does beautiful work. These cards differ from my originals mostly in that the resistors are tantalums. There are a few PRP films used but just because the tants were not available. Probably overkill but it will be interesting to see if these are "warmer" in voicing than my others. Chuck will have my MR70 line amps done soon and that is what I am really waiting for.
I have about 15 hours on these and the first thing I noticed is that I can turn the Accuphase volume pot to about 2:30 before I get noise.The 1st generation is about 12:30....So to my ear these are quieter. Usually with Blackgate caps they will form up and the gain will stabalize after about 200 hours,so these will be really quiet. The BG Fk's & Nx's are about -160db
Looks like the 1st gen will get some new resistors and maybe 2 foils too.
I found a 30 off sales on some teflon .1uf 400v caps and will have them Thursday. These tants are quite a lot quieter than the other resistors and the 2 dollar nichicon films(.1uf 800v) although very good are a tad over done here. The teflons should take advantage of the better resistors. I guess V2.1....I can't really see what else can be done. While these are stellar sounding they will never approach the power and majesty of a 350 or even the nuvistor MR70. Now this is the record side of these preamps. The playback is a whole different deal and is where the 440 gets close.
We have a octal based dual mono,seperate power supply,with tons of capacitance and filtering preamp,going against a similar design in solid state,but the solid state has only one tenth the physical capacitance and there lies the rub.Both are extremely quiet,but the 350 has mountains of headroom and can nitrous the Accuphase preamp and in turn the Accuphase can drive the solid state amplifiers with total domination. The 350's done right are a mind blower,I can't say enough about them. The MR70 surely has the design,it will be interesting to see how if fares against it's older brother.
The 350
I have about 15 hours on these and the first thing I noticed is that I can turn the Accuphase volume pot to about 2:30 before I get noise.The 1st generation is about 12:30....So to my ear these are quieter. Usually with Blackgate caps they will form up and the gain will stabalize after about 200 hours,so these will be really quiet. The BG Fk's & Nx's are about -160db
Looks like the 1st gen will get some new resistors and maybe 2 foils too.
I found a 30 off sales on some teflon .1uf 400v caps and will have them Thursday. These tants are quite a lot quieter than the other resistors and the 2 dollar nichicon films(.1uf 800v) although very good are a tad over done here. The teflons should take advantage of the better resistors. I guess V2.1....I can't really see what else can be done. While these are stellar sounding they will never approach the power and majesty of a 350 or even the nuvistor MR70. Now this is the record side of these preamps. The playback is a whole different deal and is where the 440 gets close.
We have a octal based dual mono,seperate power supply,with tons of capacitance and filtering preamp,going against a similar design in solid state,but the solid state has only one tenth the physical capacitance and there lies the rub.Both are extremely quiet,but the 350 has mountains of headroom and can nitrous the Accuphase preamp and in turn the Accuphase can drive the solid state amplifiers with total domination. The 350's done right are a mind blower,I can't say enough about them. The MR70 surely has the design,it will be interesting to see how if fares against it's older brother.
The 350
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Moving right a long with the other 1/4 inch MR70 transport.....the control board updated. Now that my friend and tech Clayton has joined my MR70 team. I am hoping to get these last two MR70 transports up and running. Three are already running,which would make a mind boggling 5 running MR70's. I should sit back and smell the roses.
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Don thanks again and funny...you should say that...good chance I'll pick up another 440 transport tomorrow.
The final version of the AG440 cards are finished. I replaced the Nichicon .1uf with Rel-cap teflons .1uf 400v, I can't see how one could squeeze anymore out of these. Also have the 1/4 inch MR70 transport powered up and running today,that makes 4 operational and at least one more to go.....wonderful.
I did trade for a very clean AG440C DC servo in console. I will use these cards and the machine will be a 1/2 inch 2 track with ME heads.
Record cards
What did Madeline Kahn say in Blazing Saddles.....It's True! It's True!....about Teflon that is. I am so screwed...thank God all my Ampex only require 2 .1uf 400v per channel. Teflon is like a antiseptic for noise. I am going to wait on my 350's though till these in the 440 and MR70's break in.
I did trade for a very clean AG440C DC servo in console. I will use these cards and the machine will be a 1/2 inch 2 track with ME heads.
Record cards
What did Madeline Kahn say in Blazing Saddles.....It's True! It's True!....about Teflon that is. I am so screwed...thank God all my Ampex only require 2 .1uf 400v per channel. Teflon is like a antiseptic for noise. I am going to wait on my 350's though till these in the 440 and MR70's break in.
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MR70 line amps are done. I love doing this.
Hey Myles....I wish you could hear these.....stunning.
Original
Hey Myles....I wish you could hear these.....stunning.
Original
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MR70 line amps are done. I love doing this.
Hey Myles....I wish you could hear these.....stunning.
Original
Which Teflons did you stuff in the machine?
The Rel's were on sale,so I couldn't pass it up and I just finished burning in this cap on my 440 and it does everything a teflon should. The Solen's are reported to be very close to the V-cap. These are small values so I'll probably give the V-caps a try just to hear them. With the Nuvistor everything is fleshed out.....really have never heard it like this. I also think the Vishay foils enable the Nuvistor to strut it's stuff.
Size was also taken into consideration wanted everything to fit nicely and no crowding.
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Understood, size is always an issue with Teflons. There are so many good caps out there nowadays eg. the V-Caps, Dueland, Clarity, Mundorf, etc.
MR70 that is....
Update 09/19/2013 After initially sounding better than anything I have ever heard, 20 hours into listening this nuvistor preamp continues to amaze me. Playing Reference Recordings Stravinsky netted a low end in my system that the tympanies rippled through my room and that was at low volume. I even got a call from my next door neighbor saying the bass was too much and his wife was trying to sleep, no problem as I turned it down and cut off the sub. the sub was set at 30hz and the volume was at the lowest setting. Needless to say,the nuvistor makes the transistor and vacuum tube obsolete!
This is a 7895 RCA nuvistor and can be purchased NOS for as little as 3 dollars
http://www.ko4bb.com/Manuals/RCA/RCA_7895_Nuvistor.pdf
For comparison
http://www.tubeaudiostore.com/suitof6dfora.html
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