Ampex electronics for the best possible sound

[mep]

That picture is almost disturbing. It's like the audiophile equivalent of the that TV show "Hoarding" which I can't watch for more than a minute because it makes me sick.

 

[RogerD]

That picture is almost disturbing. It's like the audiophile equivalent of the that TV show "Hoarding" which I can't watch for more than a minute because it makes me sick.

That's why this is my last deck. Please O'Lord give me strength.

 

[MylesBAstor]

That's why this is my last deck. Please O'Lord give me strength.

You need to pray to St. Jude

 

[MylesBAstor]

That picture is almost disturbing. It's like the audiophile equivalent of the that TV show "Hoarding" which I can't watch for more than a minute because it makes me sick.

LOL...great show....I've had friends look at LP collections in people's apts. who were obviously hoarders

 

[MylesBAstor]

Gee, I had to look twice, thought for a second it was my work area from a different angle. Then I caught sight of the R2R ...

Frank

Gotta hand it to you Frank. You certainly don't take yourself seriously

 

[RogerD]

Well it's a start,more tomorrow.

 

[MylesBAstor]

Well it's a start,more tomorrow.

She's a beauty Roger

 

[mep]

The MR-70 looks like the result of an Ampex 350 and an Ampex 440 having sex.

 

[RogerD]

She's a beauty Roger

Thanks Myles

The MR-70 looks like the result of an Ampex 350 and an Ampex 440 having sex.

Mark,

The transport is about the same size as my A820, the thing is built like a tank or a '55 Cadillac,it's so vintage.

 

[RogerD]

Starting to look like a MR70

 

[RogerD]

Thought some might like to see a photo of the underneath of the transport and the design. There are 4 motors in all,2 reel,capstan,and idler. The beige-gold oil reservoir on the left hand side is part of the idler assembly. The oil damped idler helps reduce wow and is some of the many features of the MR70. The buna rubber flywheel is the same design of the large 300 type transport.

I am hoping to get the electronics harness made this week and then I can listen to the electronics using the Accuphase tape monitor feature,just like I do with the rest of my decks. Soon I can compare the sound of the MR70,440,350's and my A820. Nothing like having 5 preamps in one.

 

[MylesBAstor]

Thought some might like to see a photo of the underneath of the transport and the design. There are 4 motors in all,2 reel,capstan,and idler. The beige-gold reservoir on the left hand side is part of the idler assembly. The oil damped idler helps reduce wow and is some of the many features of the MR70. The buna rubber flywheel is the same design of the large 300 type transport.

I am hoping to get the electronics harness made this week and then I can listen to the electronics using the Accuphase tape monitor feature,just like I do with the rest of my decks. Soon I can compare the sound of the MR70,440,350's and my A820. Nothing like having 5 preamps in one.

That looks brand new

 

[RogerD]

That looks brand new

I hope so,many hours went into this baby! Charles Richardson did a great job. I'm doing the easy stuff.

Thanks Myles

 

[Tom B.]

Good observation, but the other way around. Quite a few engineering and construction practices from the MR70 carried over to the 440 series. Cast deck plate, more modular construction, 3-point mounting schemes, fluid-damped idler (on some 440's) etc etc.

Tom

The MR-70 looks like the result of an Ampex 350 and an Ampex 440 having sex.

 

[Tom B.]

Roger-

You rock! Looks great.

Tom

 

[RogerD]

Roger-

You rock! Looks great.

Tom

Thanks Tom!

 

[RogerD]

Well things are moving on the headstack. I am thinking of having John fit his best guides as I think this will make a big improvement in playback quality. I had to order a connector for the electronics,so being able to listen has been moved back a bit. I have been contacted by another user in Europe. It should be fun to trade experiences with other users. I have been listening to several recordings made with the MR70 vs other decks. I am convinced what gives the MR70 such a unique sound is the nuvistor electronics.




Good article on the MR70

"The MR70 is an unusual machine in that, first of all, it was the last tube machine that Ampex ever made, but second, it was never marketed. They put three years of solid R&D into the project in the mid '60s, selecting parts that would be typical of some high-end audio company today: they used gold connectors, they selected the capacitors, in fact all passive components, on the basis of sound quality as well as long-term reliability. They used the very best components that money could buy at that time. The cast frame on to which the transport is mounted is probably one of the heaviest made. The transport itself is unique. It uses a silicone-damped reel idler that does not exist on any other machine. The MR70 uses a very heavy flywheel with a very good scrape-flutter filter, and there are even air grooves cut on the guides that the tape runs over. People who have worked on old Ampexes—there is an elderly gentleman up north who has helped me a lot with this machine—he tells me that the MR70 has the lowest wow & flutter of any machine Ampex ever made."

http://www.stereophile.com/content/poem-istereophilei-cuts-lp-recording-engineer-part-2

http://www.historyofrecording.com/AMPEX_MR-70.html

 

[Tom B.]

Roger,

If I may go off-track a bit, you've done some tube rolling in your 350's, correct? I've not used anything but the original metal-can types, particularly in the repro gain stage (12SJ7), but I'm sure there are some of the GT variety that might work better. Any suggestions?

And.......how's the MR going?

Thx,
Tom

 

[RogerD]

Roger,

If I may go off-track a bit, you've done some tube rolling in your 350's, correct? I've not used anything but the original metal-can types, particularly in the repro gain stage (12SJ7), but I'm sure there are some of the GT variety that might work better. Any suggestions?

And.......how's the MR going?

Thx,
Tom

Tom,

The cables were made and I will do some critical listening tonight and let you know what I think about their sound. I can compare them within tenths of a second between my 350 and 440,it should be interesting. They are really beautiful electronics.

 

[RogerD]

Like I said I have the electronics up and running. My first impression is the sound is unique indeed,at first listen it has kind of a FM broadcast quality but not colored. If anybody has listened to Allnic Audio's nuvistor based gear maybe they can comment on the nuvistor sound.

The 350's while neutral sounding they do have a "bloom" quality. The MR70 has instead of bloom, I would call it "presence". Which one is more correct? I'll try and answer that question later.

Hmm...I found this comment by Scott Dorsey....

"The nuvistor is the most amazing tube design ever. Definitely the pinnacle of the thermionic art. However, it was too little and too late....."

Scott Dorsey.

We shall see.

Also found this on our own WBF by cjfrbw

http://www.whatsbestforum.com/showt...Nuvistor-Tube-Phono-(first-post-December-2009)


NUVISTORS:

There is a pretty nice, succinct write up on nuvistors on wikipedia: http://en.wikipedia.org/wiki/Nuvistor. The nuvistor Ampex MR-70 was considered one of the best if not the best sounding studio reel to reel tape recorder ever made. There were perhaps 50 samples of the MR-70, all more or less custom made.

Conrad Johnson made a couple of nuvistor based head amps in the 1980's, the HV1 and HV1a and HV2. The circuit boards were suspended with rubber bands for microphonics of the nuvistors, and the sound was considered good.

Musical Fidelity has used nuvistors in its "Nuvista" and "Trivista" product lines The Musical Fidelity nuvistor units are sought after as used product.

Suffice it to say, nuvistors were the last gasp of the vacuum tube industry facing impending obsolesence from semi conductors.

Nuvistors were an attempt at miniaturizing tubes to compete with transistors. They are small, thimble like metal tubes that needed complete vacuum controlled chambers for assembly and production. They were mostly used for TV's of the time.