|
|
Post by hadaja on Apr 6, 2018 19:21:31 GMT -6
Hey there I remember reading some stuff on the UTC input transformers.
I cant remember or see what UTC a-11's were good for as I found one in my box of spares and am deciding what to do with it as I am cleaning out stuff.
Not sure why I also have Cinemag Cm 2480's as spares but I will get top them later. Thanks
|
|
|
|
Post by gouge on Apr 6, 2018 20:17:44 GMT -6
Its a MIC input transformer. Gets some love by audiohiles for turntable step up.
Could wire backwards for a di.
The a10 is the famous brother. Got used in the la2a and was wired backwards in some well thought of di's.
They have different max level spec so would saturate differently.
|
|
|
|
Post by EmRR on Apr 6, 2018 21:26:09 GMT -6
A-11's have a bit of treble boost, A-10's don't. Both good for mic inputs. You won't hear any saturation difference unless you push them crazy hard. with a volume pot AFTER them before a gain stage.
|
|
|
|
Post by gouge on Apr 7, 2018 1:40:20 GMT -6
A-11's have a bit of treble boost, A-10's don't. Both good for mic inputs. You won't hear any saturation difference unless you push them crazy hard. with a volume pot AFTER them before a gain stage. Are you saying at line level I would not hear saturation..? Thx |
|
|
|
Post by EmRR on Apr 7, 2018 8:21:14 GMT -6
A-11's have a bit of treble boost, A-10's don't. Both good for mic inputs. You won't hear any saturation difference unless you push them crazy hard. with a volume pot AFTER them before a gain stage. Are you saying at line level I would not hear saturation..? Thx Both are rated at +15dBm in the catalogs I've checked, revising back. +15dBm is for the lowest rated frequency, so yes, 30Hz (if it exists) will be at 1% distortion, 60Hz won't hit 1% until +21dBm. 120Hz until +27dBm. That's how transformer ratings work. Unless 'saturation' is something other than distortion, I'm not fond of the word (personal problem), it's vague to me. I live in a world of low level 'saturation' probably, because everything here is always through a bunch of those type old transformers, but I don't push them into those ranges for the most part, mainly because the old circuits following them don't take it well IMO, they are designed for input levels 20dB (or more) lower than the transformer ratings. The associated output transformers after the gain MAY be the primary source, but usually it's the active gain stages that are near overload, not the transformers. |
|
|
|
Post by johneppstein on Apr 7, 2018 13:44:43 GMT -6
Its a MIC input transformer. Gets some love by audiohiles for turntable step up. Could wire backwards for a di. Are you quite certain of that? The input impedance of a DI box needs to be VERY high - I would not expect the secondary of a typical mic input transformer to work well (or possibly at all). You can turn around a mic input transformer intended for connecting a Low Z mic to a guitar amp but that's a very different thing that a typical input transformer in a mic preamp. |
|
|
|
Post by johneppstein on Apr 7, 2018 13:57:34 GMT -6
Are you saying at line level I would not hear saturation..? Thx Both are rated at +15dBm in the catalogs I've checked, revising back. +15dBm is for the lowest rated frequency, so yes, 30Hz (if it exists) will be at 1% distortion, 60Hz won't hit 1% until +21dBm. 120Hz until +27dBm. That's how transformer ratings work. Unless 'saturation' is something other than distortion, I'm not fond of the word (personal problem), it's vague to me. I live in a world of low level 'saturation' probably, because everything here is always through a bunch of those type old transformers, but I don't push them into those ranges for the most part, mainly because the old circuits following them don't take it well IMO, they are designed for input levels 20dB (or more) lower than the transformer ratings. The associated output transformers after the gain MAY be the primary source, but usually it's the active gain stages that are near overload, not the transformers. If I'm not mistaken, the word "saturation" means something somewhat different for transformers than its common useage these days in general circuitry, where it's generally understood to mean the onset of clipping. In a transformer saturation specifically means the level at which the magnetic field saturates the ferromagnetic core. In other words, saturation in a transformer causes distortion but technically it isn't itself distortion. And it's frequency dependent, as the low frequency performance of a transformer depends on the amount (and metallurgic composition) of ferromagnetic material in the core. It's kinda like a sponge - when a sponge is saturated it can't absorb any more water. When a transformer core is saturated it can't absorb any more magnetism (so additional energy turns into heat.) Now, depending of the physical design of the core and coils it's possible (and common) for a transformer to add distorttion which is not related to/caused by saturation, so the two terms aren't really interchangeable. |
|
|
|
Post by johneppstein on Apr 7, 2018 15:34:35 GMT -6
A-11's have a bit of treble boost, A-10's don't. Both good for mic inputs. You won't hear any saturation difference unless you push them crazy hard. with a volume pot AFTER them before a gain stage. Are you saying at line level I would not hear saturation..? Thx Line level? What "line level"? Last time I looked there was no definite specification for "line level". I've run into professional consoles that are capable of producing +30dBm before clipping from their line outputs. And without saturating their (rather hefty) output transformers. The common "+4" that you see on prosumer gear is a very nominal, almost minimum figure. Nearly every real professional class device is capable of much more. |
|
|
|
Post by winetree on Apr 7, 2018 16:02:53 GMT -6
|
|
|
|
Post by Bob Olhsson on Apr 7, 2018 22:29:43 GMT -6
A backward-wired A-10 is the classic direct box sound. There's a Western Electric that's even more classic that was used in Nashville and Chicago during the '40s and '50s.
|
|
|
|
Post by gouge on Apr 8, 2018 1:10:13 GMT -6
Are you saying at line level I would not hear saturation..? Thx Both are rated at +15dBm in the catalogs I've checked, revising back. +15dBm is for the lowest rated frequency, so yes, 30Hz (if it exists) will be at 1% distortion, 60Hz won't hit 1% until +21dBm. 120Hz until +27dBm. That's how transformer ratings work. Unless 'saturation' is something other than distortion, I'm not fond of the word (personal problem), it's vague to me. I live in a world of low level 'saturation' probably, because everything here is always through a bunch of those type old transformers, but I don't push them into those ranges for the most part, mainly because the old circuits following them don't take it well IMO, they are designed for input levels 20dB (or more) lower than the transformer ratings. The associated output transformers after the gain MAY be the primary source, but usually it's the active gain stages that are near overload, not the transformers. Thanks. I must have looked it up wrong I thought the a11 was +3. |
|
|
|
Post by hadaja on Apr 8, 2018 1:31:10 GMT -6
Can the A-11 work backwards as a DI and how do you do this?
|
|
|
|
Post by gouge on Apr 8, 2018 6:32:05 GMT -6
|
|
|
|
Post by johneppstein on Apr 9, 2018 21:07:00 GMT -6
I disagree. The "nominal" +4 is actually a MINIMUM figure. It's only in the age of common "prosumer" gear that people have started taking it as "the standard". I probably would not want a "line level" device that was only capable of handling a +4 input level due to a severe lack of headroom. |
|
|
|
Post by johneppstein on Apr 9, 2018 21:10:53 GMT -6
Both are rated at +15dBm in the catalogs I've checked, revising back. +15dBm is for the lowest rated frequency, so yes, 30Hz (if it exists) will be at 1% distortion, 60Hz won't hit 1% until +21dBm. 120Hz until +27dBm. That's how transformer ratings work. Unless 'saturation' is something other than distortion, I'm not fond of the word (personal problem), it's vague to me. I live in a world of low level 'saturation' probably, because everything here is always through a bunch of those type old transformers, but I don't push them into those ranges for the most part, mainly because the old circuits following them don't take it well IMO, they are designed for input levels 20dB (or more) lower than the transformer ratings. The associated output transformers after the gain MAY be the primary source, but usually it's the active gain stages that are near overload, not the transformers. Thanks. I must have looked it up wrong I thought the a11 was +3. +15 is pretty typical for most gear. |
|
