Ampex electronics for the best possible sound

[Gary D]

An update on the 350 tape amps with close to 400 hours logged they have finally started to settle in.
With an overall clarity and detail that is very welcome.The sounstage projected is large to say the least and the recording venue is preserved to a point that when listening you say that is correct.What I mean by that is the music portrays what was heard through the studio monitors at the time.

I imagine everything will continue to improve but from 1st turn on to now I have noticed a marked change.
As before, any change in passive components a 500 hour to 1000 hour was needed to strike paydirt.

 

[c1ferrari]

Sorry, I missed this post...

" Originally Posted by RogerD
I hear ya, after I finish my Ampex project the A820 is next."

I have purchased a set of extra Ampex 440B electronics as I needed a set of original cards anyway and also to have a set for my "RTZ" cards.

I will probably use these as an experiment with my Studer A820 1/2 inch deck, just to see how the RTZ cards compare. Also I could duplicate the AL/BG cards if I wanted to.

I'm starting to feel like a mad hot rodder version of Ki......big trouble!

Update:

After hearing the AL/BG cards, I am really impressed with the AG440 platform. It is compact,very clean, and extremely versatile. I will over the coming months have duplicated another set of the AL/BG cards and have a very nice solid state tape preamp.

Holy Cow, Roger
AND, you're interested in hot-rodding the Studer, too
In that case, perhaps StudPex is apropos - lol

 

[RogerD]

Holy Cow, Roger
AND, you're interested in hot-rodding the Studer, too
In that case, perhaps StudPex is apropos - lol

Hi Sam,

I knew you would get a kick out of that!

If I can match up my 440 electronics to the Studer playback head and that's up in the air right now,it is something I want to do. Although the Studer sounds very good, the 440 upgraded preamps have a abilty to bring the music so much closer to me I must try it. I now use this preamp when listening to all my digital software. I can't expain it,but I have had to reduce the volume by quite a bit on my subwoofers. I have never experienced bass like this,especially from my speakers. I have had these speakers for 30 years and I had given up on the 6" Dynaudio drivers delivering a low end bass that many 15" woofers can. I no longer have that problem! I am surprised at how well the record cards sound this early. I have about 180 hours on my playback cards and they are still adding nuance. The record cards have less than half of those hours and at 200 hours they will be remarkable.
The playback cards are finished as far as my upgrading them. The record cards could be tweaked a little later,but that's for the Studer edition. Right now with their performance I am happy to just be satisfied.

 

[c1ferrari]

Hi Sam,

I knew you would get a kick out of that!

If I can match up my 440 electronics to the Studer playback head and that's up in the air right now,it is something I want to do. Although the Studer sounds very good, the 440 upgraded preamps have a abilty to bring the music so much closer to me I must try it. I now use this preamp when listening to all my digital software. I can't expain it,but I have had to reduce the volume by quite a bit on my subwoofers. I have never experienced bass like this,especially from my speakers. I have had these speakers for 30 years and I had given up on the 6" Dynaudio drivers delivering a low end bass that many 15" woofers can. I no longer have that problem! I am surprised at how well the record cards sound this early. I have about 180 hours on my playback cards and they are still adding nuance. The record cards have less than half of those hours and at 200 hours they will be remarkable.
The playback cards are finished as far as my upgrading them. The record cards could be tweaked a little later,but that's for the Studer edition. Right now with their performance I am happy to just be satisfied.

Great Roger...congrats!
It sounds -lol- like you're experiencing a different and favorable spectral balance in your system/room.
I'm still optimizing my stock A820

 

[RogerD]

Great Roger...congrats!
It sounds -lol- like you're experiencing a different and favorable spectral balance in your system/room.
I'm still optimizing my stock A820

Sam I'll keep you posted on this wild journey of mine.

 

[Tom B.]

Roger,

Weren't you at one point working on restoring Ampex 354 electronics? I seem to recall something about that from another forum a while back.

The 354 machines (electronics in particular as the transports are virtually identical to the rest of the 35X series), are relatively obscure and very little conversation comes up about them, with the exception of a few units still doing service in small studios.

I decided to tear into a 354 last week......this particular unit was clean on the outside but the internals were quite a mess; probably as dirty as they come and it was obvious that someone had been into it before. The good news was that many of the large electrolytics had been replaced properly (OK, so at least we can try to power it up), the bad news was that after staring at the schematic for a few hours it became apparent that this was a half-hearted attempt to convert it to a mic-pre.

The 354 is tough to work on with two channels or P/R electronics and power supplies crammed into one 7" high chassis, all with a single PCB containing the major circuitry. Once I got in there and reverted the mic modifications back to stock (took the better part of a day), I was surprised to find out that this unit actually passed clean 1KHz and 10KHz test signals and was ready for playback tests.

First listening with some 7.5 IPS NAB sources revealed that the 354 electronics are good......very good. The sound is classic Ampex tube....full and lush, with perhaps a noise floor that lower than even the best of the 351s. I am almost disappointed I had not given the 354s much attention recently, in fact I had shelved a few units in favor over other projects and really had little interest in rebuilding them until now.

If anyone else is running 354 tube electronics or has past experience I'd like to hear further comments.....

Tom B.

 

[RogerD]

Roger,

Weren't you at one point working on restoring Ampex 354 electronics? I seem to recall something about that from another forum a while back.

The 354 machines (electronics in particular as the transports are virtually identical to the rest of the 35X series), are relatively obscure and very little conversation comes up about them, with the exception of a few units still doing service in small studios.

I decided to tear into a 354 last week......this particular unit was clean on the outside but the internals were quite a mess; probably as dirty as they come and it was obvious that someone had been into it before. The good news was that many of the large electrolytics had been replaced properly (OK, so at least we can try to power it up), the bad news was that after staring at the schematic for a few hours it became apparent that this was a half-hearted attempt to convert it to a mic-pre.

The 354 is tough to work on with two channels or P/R electronics and power supplies crammed into one 7" high chassis, all with a single PCB containing the major circuitry. Once I got in there and reverted the mic modifications back to stock (took the better part of a day), I was surprised to find out that this unit actually passed clean 1KHz and 10KHz test signals and was ready for playback tests.

First listening with some 7.5 IPS NAB sources revealed that the 354 electronics are good......very good. The sound is classic Ampex tube....full and lush, with perhaps a noise floor that lower than even the best of the 351s. I am almost disappointed I had not given the 354s much attention recently, in fact I had shelved a few units in favor over other projects and really had little interest in rebuilding them until now.

If anyone else is running 354 tube electronics or has past experience I'd like to hear further comments.....

Tom B.

Hi Tom,

Yes I have a 354 that I acquired some time ago. It was a mess,so when I found my 350's that became a priority. It's good to hear that the 354 sounds that good. I have both brown and blue boards for it. The blue board is NOS and I have read that it is more desirable. Maybe someday I will restore it. With the 350's,440's and a MR70 it's hard to get motivated on my 354,but at least I have one and that's part of the battle. I have thought that after I'm finished I would like to have a pair of 351's,but it sounds like a 354 might be worth restoring and with less money invested as 351's are currently bringing 800-1000 a pair un-restored.

 

[Tom B.]

One of my motivations for giving the 354 a chance was the assumption, and it is nothing more than a guess, was that as it was among the last of the tube electronics in the Ampex timeline the design would have benefited from all of the experiences of the preceding units.

The other factor was the convenience of having two channels of tube electronics in one 7" (4u) rack space, power supplies inclusive. Although the assembled unit is densely-packed, the design is straightforward and easy to understand, and I see no reason why it would not be a good performer, or at least on par with the rest of the Ampex equipment of that series.

Tom B.

 

[c1ferrari]

Cool Roger

Sam I'll keep you posted on this wild journey of mine.

I'm interested in your sonic journey

 

[RogerD]

I'm interested in your sonic journey

I have decided to upgrade my stock Studer A820 cards,instead of the StuderPex idea. Luckily the Studer uses very common values on the reproduce boards and Black gate caps are available,as I had most of the values in my stash. I will start a new thread as this progresses.

 

[tony ky ma]

I have decided to upgrade my stock Studer A820 cards,instead of the StuderPex idea. Luckily the Studer uses very common values on the reproduce boards and Black gate caps are available,as I had most of the values in my stash. I will start a new thread as this progresses.

Roger--I only have A80 and A810 circuit in hand, A820, I guess it will be similar to A810. each stage in repro amp has a in-put and out-put cap to block the DC, those caps will have a bigger effect to main quality, but the value will be 10uf to 50 50uf, and the size will be very big in a good sounding cap. so it is not easy like your Ampex project got enough rooms
tony ma

 

[RogerD]

Roger--I only have A80 and A810 circuit in hand, A820, I guess it will be similar to A810. each stage in repro amp has a in-put and out-put cap to block the DC, those caps will have a bigger effect to main quality, but the value will be 10uf to 50 50uf, and the size will be very big in a good sounding cap. so it is not easy like your Ampex project got enough rooms
tony ma

Tony,

Here is the capacitor complement:

5 47uf 16v
1 4.7uf 6.3v
1 220uf 6.3v
2 100uf 25v
4 10uf 16v

Yes there is room and I will probably stay with the stock opamps but they can be swapped out also.

 

[tony ky ma]

Tony,

Here is the capacitor complement:

5 47uf 16v
1 4.7uf 6.3v
1 220uf 6.3v
2 100uf 25v
4 10uf 16v

Yes there is room and I will probably stay with the stock opamps but they can be swapped out also.

Roger
Up to 47uf should be coupling caps, 100 &220uf like to be the bypass cap, voltage range higher than the original should be fine no matter how high of the new cap. non polarity cap for coupling use is sound better than with polarity kind, biggest value for a non polarity cap is 100uf (Solen) but size huge.
Ideal cap for coupling should be metal foil & paper in oil but only up to 2uf, every different cap will sound it's own just up to your favor
tony ma

 

[RogerD]

MR70 Motors are done

 

[c1ferrari]

Terrific...

I have decided to upgrade my stock Studer A820 cards,instead of the StuderPex idea. Luckily the Studer uses very common values on the reproduce boards and Black gate caps are available,as I had most of the values in my stash. I will start a new thread as this progresses.

I'll be attentive to developments. Any consideration for maintaining stock AND modded sets of cards, Roger? It would be awesome to have them both available

 

[RogerD]

I'll be attentive to developments. Any consideration for maintaining stock AND modded sets of cards, Roger? It would be awesome to have them both available

Hi Sam,

Two sets of cards would be nice,but I doubt if I could find the same versions as the deck was made in 1992. There is no need to change resistors or opamps so this will be a easy upgrade. I had most of the cap values left over from prior projects and since I have found that Blackgate caps alone produce a "sound" that is very pleasing, I'm going this direction. I have my Ampex benchmark to compare the two and for a very reasonable cost without all the associated problems of adding a non-stock preamp,this makes better sense to me. I view using the original design and footprint as the best option.

The Blackgate N/NX series is -150db and the FX is -160db. They both have their different qualities so I always mix the two with great results.

 

[tony ky ma]

I'll be attentive to developments. Any consideration for maintaining stock AND modded sets of cards, Roger? It would be awesome to have them both available

Sam
In my experience, each time the modification of the R2R, I did put a selector switch that can make it back to the stock, but every time that can only use for a couple time after modification was done because the improvement made it so different and will not listen to the stock again also like to cut them off to save materials or shorten sound path and conducts to make it more better, the only reason still keep them in is for showing the different to friends, what a wast !
tony ma

 

[RogerD]

Sam
In my experience, each time the modification of the R2R, I did put a selector switch that can make it back to the stock, but every time that can only use for a couple time after modification was done because the improvement made it so different and will not listen to the stock again also like to cut them off to save materials or shorten sound path and conducts to make it more better, the only reason still keep them in is for showing the different to friends, what a wast !
tony ma

Hi Tony,

I agree! usually the originals go to the closet,never to be seen or heard again.

 

[c1ferrari]

Hi Sam,

Two sets of cards would be nice...I view using the original design and footprint as the best option.

I'm of a similar ethos, Roger.

I prefer optimizing an original factory stock product from a top-tier company by ensuring it's operating at optimal factory specification rather than modifying it...that way, I have a superb idea of the original designer's/manufacturer's concept of excellence.

Now, should I be favored with another unit...I would seriously contemplate minor, easily reversible performance enhancements. For example, with a Ferrari -- I might consider exchanging the stock exhaust, i.e. cats, etc., for a Tubi, while maintaing all of the original parts for future needs

Roger, is your two-channel system listed somewhere

 

[c1ferrari]

Sam
In my experience, each time the modification of the R2R, I did put a selector switch that can make it back to the stock, but every time that can only use for a couple time after modification was done because the improvement made it so different and will not listen to the stock again also like to cut them off to save materials or shorten sound path and conducts to make it more better, the only reason still keep them in is for showing the different to friends, what a wast !
tony ma

Haha, Tony How wonderful to have your abilities! Currently -lol-, I'm developing some basic skills with test and measurement gear. Maybe, you should forget the selector switch...what do you think