i am a subscriber to the Ampex List and do scan all the posts and read some of them. lots of it is over my head.
Dave D. called me back today. he has some 351 transports and suggests i do a complete Ampex 351, which sounds good to me. when i get the 351 mic pre's we'll move forward with that. rather than try to modify the ATR i'm more comfortable with this direction. having an expert on these Ampex machines locally makes this a no brainer for me. thanks again for the suggestion.
That's good,as these conversions can look easy and promising,but these machines are in fact very complicated. Your lucky to have Dave in the area and if he is involved and supplies the transport,you can't ask for more than that. I think you'll find as I have these machines have their signature sounds,not better per se just different. Enjoy your Ampex tubed 351's as many get addicted to their big warm sound.
That's good,as these conversions can look easy and promising,but these machines are in fact very complicated. Your lucky to have Dave in the area and if he is involved and supplies the transport,you can't ask for more than that. I think you'll find as I have these machines have their signature sounds,not better per se just different. Enjoy your Ampex tubed 351's as many get addicted to their big warm sound.
i look at this like my time with the Garrard 301 turntable. until you get into it, you can't appreciate what it's like and enjoy it. i also have the 2A3 amps coming in 2 months. so i'll go down this road and see how i like it. when i see people enjoying a particular audio vision i like to taste it too and find out about it. there is not only one way to go. so many of the golden age jazz Lps i love were recorded with machines like this....
I finally received the MR70 roll a round yesterday. The transport will be ready to ship next week,so things are finally coming together. Once the headstack is finished, I can get this legend working. I will post some pics when finished. This machine is a investment but more than that a labor of love.
After asking the same question for some time, the general consensus is that the 351 electronics offered much improved performance over the earlier 350s. Large use of metal enveloped pentodes in the 350 required the floating mounting plate to prevent microphonics, first gain stage after repro head also required a hand-selected 12SJ7, which tend to be inherently noisy tubes especially if used in such a high gain configuration.
351 circuit design was based on triodes (glass triodes typically quieter than metal pentodes), used more neg feedback between gain stages. Tight PCB layout probably contributes to much of the 351's lower noise level.
Both are setup for NAB equalization as designed and will require some modification for IEC playback.
Although I own several sets of 350 electronics and enjoy working on them, I will admit that they can be a bit noisier than their 351 counterparts.
Mike - I'll bet you will very much enjoy their classic Ampex tube 'sound', but you will likely find the 351 transport clunky, especially after having considerable time with an ATR 102. Navigating the 350-series transport controls is something learned over time, and unlike the ATR, a 351 transport can be rough on tape under certain conditions.
After asking the same question for some time, the general consensus is that the 351 electronics offered much improved performance over the earlier 350s. Large use of metal enveloped pentodes in the 350 required the floating mounting plate to prevent microphonics, first gain stage after repro head also required a hand-selected 12SJ7, which tend to be inherently noisy tubes especially if used in such a high gain configuration.
351 circuit design was based on triodes (glass triodes typically quieter than metal pentodes), used more neg feedback between gain stages. Tight PCB layout probably contributes to much of the 351's lower noise level.
Both are setup for NAB equalization as designed and will require some modification for IEC playback.
Although I own several sets of 350 electronics and enjoy working on them, I will admit that they can be a bit noisier than their 351 counterparts.
Mike - I'll bet you will very much enjoy their classic Ampex tube 'sound', but you will likely find the 351 transport clunky, especially after having considerable time with an ATR 102. Navigating the 350-series transport controls is something learned over time, and unlike the ATR, a 351 transport can be rough on tape under certain conditions.
thanks for your explanation of the 350/351 question. most of what i've read favors the 351, but i'm sure it's a taste issue as well as specific optimized examples of both being very good.
as far as the clunky 351 transport controls, i have 2 Studer A820's...the ultimate in tape handling, and the ATR which is very good in that area too. my idea was to have one vintage deck fully funtional. i have enough NAB 15ips tapes that i really don't need IEC on this machine. it's more that i could output NAB tapes thru these electronics and dub with that sound onto whatever i wanted to (1/2" A820 likely). also; i was planning on maybe doing some live recording in my room and using this as a recording machine might be nice with those inputs.
thanks for your explanation of the 350/351 question. most of what i've read favors the 351, but i'm sure it's a taste issue as well as specific optimized examples of both being very good.
as far as the clunky 351 transport controls, i have 2 Studer A820's...the ultimate in tape handling, and the ATR which is very good in that area too. my idea was to have one vintage deck fully funtional. i have enough NAB 15ips tapes that i really don't need IEC on this machine. it's more that i could output NAB tapes thru these electronics and dub with that sound onto whatever i wanted to (1/2" A820 likely). also; i was planning on maybe doing some live recording in my room and using this as a recording machine might be nice with those inputs.
Mike
If you try to entry to the area of live recording, you will find that you are stepping into a new broader of audio, invest high quality mic and pre amp for your Studer A820, use GP9/499 tape, listen to the master tape that you recorded and compare to those copied tapes in hand, then you will know what is the highest level of repro sound
cheers
tony ma
...invest high quality mic and pre amp for your Studer A820, use GP9/499 tape, listen to the master tape that you recorded and compare to those copied tapes in hand, then you will know what is the highest level of repro sound
cheers
tony ma
Sam
I don't have A820, so I did only try different tapes in A80, GP9 is the most highest out put, 499 ( Quantegy or Ampex ) slightly softer than GP9, 3M 996 also sound good after baked, I think all this tape are good for all Studer's models
tony ma
Just some thoughts on the 350's, as I noted in another post,the slave unit's output transformer had started to open up and that unit had a intermittent static that was very hard to track down. I wish I had my 354 up and running or a pair of 351's to compare them too. When I decided to rebuild the 350's I did so expecting a cold solder joint,a bad capacitor(s) or resistor(s) to be the problem. If the output transformer had been diagnosed early on, I don't know if I would have rebuilt them,live and learn.
One thing, all that added high dollar capacitance has done has changed the bass for the better,very soild with plenty of detail and power.The jury is still out whether these produce as quiet a background as the units did before. I have made so many changes I have to get a handle still on what I am actually hearing. Another thing I think that has improved the 350's is that I have replaced all the metal canned military tubes with glass GTA variants, I think this has been a improvement.
As I said, having not heard the 351,354 series I have nothing to compare them to except my hot rodded 440 and they both compare very well to each other. Maybe after I finish the MR70 I will have to try a set of 351's,but the 350's are still not totally up to speed so I will make that descision later.
Just one other thought after looking at a posted pix of the rebuilt 350,by golly that's a lot of capacitance there. It sure well better sound good, If it doesn't improve over the prior orange drops (712's)quiet background,oh well!
That would be the "select" tube. I have rolled several different brands and settled on one in particular,great bass,lush mids and very extended high end. Unfortunately hard to come by but not expensive like other tubes. The 6sn7 also seems to effect the sound,so I use a CV1988,very nice tube.
i am a subscriber to the Ampex List and do scan all the posts and read some of them. lots of it is over my head.
Dave D. called me back today. he has some 351 transports and suggests i do a complete Ampex 351, which sounds good to me. when i get the 351 mic pre's we'll move forward with that. rather than try to modify the ATR i'm more comfortable with this direction. having an expert on these Ampex machines locally makes this a no brainer for me. thanks again for the suggestion.
today i finally dropped off my 350-2 and my -2- 351 mic pre's at Dave's studio. Dave looked over the 350-2 and said it was rare to find a complete stereo original 350. he thought it looked in very nice shape and hopefully in a few months i'll be enjoying it.
today i finally dropped off my 350-2 and my -2- 351 mic pre's at Dave's studio. Dave looked over the 350-2 and said it was rare to find a complete stereo original 350. he thought it looked in very nice shape and hopefully in a few months i'll be enjoying it.
That is great news and having a stereo pair is very nice. Will Dave be doing a recap of any sort?
Dave IIRC uses Sprague orange drops as he is a big fan of them. I think considering their reasonable cost, you might use Sprague's highest grade 716P series, they run a little over a dollar a piece. FWIW
That is great news and having a stereo pair is very nice. Will Dave be doing a recap of any sort?
Dave IIRC uses Sprague orange drops as he is a big fan of them. I think considering their reasonable cost, you might use Sprague's highest grade 716P series, they run a little over a dollar a piece. FWIW
he intends to completely recap it; but he did not make a point that he would be using any particular caps. i assume you are suggesting that i should tell him to upgrade the caps to the better ones? right? 716P....sounds good to me. are there 'even better' ones which fit that cost more and make sense?
he thought the heads looked quite good, and that they had been replaced along the way (probably in the 60's, he thought). the unit was said (by the seller) to have not been touched in 25-30 years, which Dave said was likely and why it was so complete and in nice condition. the travel cases likely protected it from missing parts and environmental damage over the years.
Dave seemed anxious to get into it. he said the travel boxes had some value, so i can sell them as i'm having it installed on a wheeled rack.
he intends to completely recap it; but he did not make a point that he would be using any particular caps. i assume you are suggesting that i should tell him to upgrade the caps to the better ones? right? 716P....sounds good to me. are there 'even better' ones which fit that cost more and make sense?
he thought the heads looked quite good, and that they had been replaced along the way (probably in the 60's, he thought). the unit was said (by the seller) to have not been touched in 25-30 years, which Dave said was likely and why it was so complete and in nice condition. the travel cases likely protected it from missing parts and environmental damage over the years.
Dave seemed anxious to get into it. he said the travel boxes had some value, so i can sell them as i'm having it installed on a wheeled rack.
Dave has done plenty of 350's,so his opinion carries weight and IHHO the Sprague orange drops sound as close to the original as he has found. Sprague makes 3 grades of orange drops,714P,715P, and the 716P series. The 716P has copper leads and is a better cap in my opinion. For the minimal upgrade in cost to me it's a no brainer.
The Sprague caps are favorites among most that upgrade Ampex electronics. My 350's were custom voiced to my ears and the parts were over 1,000+ $$. Can I tell the difference between the two, I think so but it's probably a case of is it worth the last 5 pct ? The biggest hurdle is finding somebody willing to upgrade these, few and far between.
If any resistors are needed Dave probably will have his thoughts and I would go with his recommendation. Later you might consider upgrading to a set of glass (GT) type tubes versus the military type metal cans. When you get that far email me and I can help you. As you know select tubes can make a difference.
Have Dave make you a set of IC's as the older Ampex cables use a different ground configuration. I think it's neet that you purchased a set of 350's as I consider them to be a great tube circuit preamp.
LOL 
