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Author Topic: Recreating Mike Millard Analog Recording Set-Up: AKG 451E CK-1 > Nakamichi 550  (Read 3098 times)

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Offline JEMS

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I'll probably be in Sunnyvale this weekend or at least once more before your September need.  I have the Neumann BS48i-2 that Roger linked above that you can borrow.  It runs on a 9V battery and has the 5-pin to dual XLR breakout cables.
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I would like to take you up on that. I live in LA but I will be going to Berkeley for the shows. Can we connect via PM?

BK

Offline ycoop

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I'll probably be in Sunnyvale this weekend or at least once more before your September need.  I have the Neumann BS48i-2 that Roger linked above that you can borrow.  It runs on a 9V battery and has the 5-pin to dual XLR breakout cables.

I would like to take you up on that. I live in LA but I will be going to Berkeley for the shows. Can we connect via PM?

BK
[/quote]

Which shows? (I live in Berkeley)
Avantone CK-1s > DR-60d mkII, DR-22wl

Offline rigpimp

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I'll probably be in Sunnyvale this weekend or at least once more before your September need.  I have the Neumann BS48i-2 that Roger linked above that you can borrow.  It runs on a 9V battery and has the 5-pin to dual XLR breakout cables.

I would like to take you up on that. I live in LA but I will be going to Berkeley for the shows. Can we connect via PM?

BK
[/quote]

It doesn't sounds like any of my family is in town this weekend but the wife wants to head somewhere.  I know that you said you are seeing a show in Berkeley but which direction are you coming from?  I'll shoot a PM
Mics: Schoeps MK5 G MP, Schoeps CCM 4 Lg MP, Schoeps MK8 MP, nBob cables > PFA, KCY 250/5 > PFA
Pre/A>D/P48: Sonosax SX/M2, Sonosax SX/M2-LS, E.A.A. PSP-2, Naiant Tinybox, Neumann BS48i-2 (for sale)
Recorders: Sound Devices Mixpre-6, Sony PCM-M10
Playback: McIntosh MC 2105 > McIntosh MX 130 > Von Schweikert VR-4 JR
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Offline Popmarter

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follow this
Currently in use:
Recorders: Edirol R44, Sony M10 & Sony D6
Microphones: Milab VM-44 Links (cards), AT853 (cards) & Nakamichi CM300 (all CP-s)
Preamps: JK Laboratories DVC-X-17b, Naiant IPA & Nakamichi MX-100 modded for 9v battery use
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Offline DSatz

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just a caution that unmodified, original C 451s draw about 6 mA apiece at 48 Volts, while the Neumann BS 48i-2 phantom power supply is rated at only 5 mA maximum per microphone.

Also, since that supply runs on a single 9-Volt battery for both microphones combined, I'd really want to test the battery life before going out to record live with that particular set of equipment. Oddly, Neumann doesn't specify battery life for the two-channel version of the supply at all--only for single microphones that draw 2 mA ("at least 20 hours") or 4 mA ("about 8 hours") respectively.

Note that those numbers aren't in direct proportion to one another; drawing more current evidently drains the battery faster than you would expect from a linear function. Higher current apparently leads to lower DC conversion efficiency--and you will be pushing the circuit to its limit, and maybe even a bit beyond.

Thus you may find that the battery only lasts 2-1/2 or 3 hours. Is that long enough? And/or do you have lithium batteries available?

--best regards
« Last Edit: September 05, 2018, 11:01:10 PM by DSatz »
music > microphones > a recorder of some sort

Offline noahbickart

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Does anyone argue that there are audible differences between phantom power supplies?

I understand using classic transducers, and, to a lesser extent, microphone preamps to shape the sound. But power supplies?
Recording:
Capsules: Schoeps mk41v (x2), mk4v (x2), mk22 (x2), mk3 (x2), mk21 & mk8
Cables: 2x nbob KCY, 1 pair nbob actives, Darktrain 2 and 4 channel KCY extensions:
Preamps:    Naiant Littlebox, Naiant IPA, Naiant PFA, Sound Devices Mixpre6
Recorders: Sound Devices Mixpre6, Sony PCM m10

Home Playback: Mytek DSD 192> McIntosh MC162> Eminent Tech LFT-16; Musical Fidelity xCan v2> Hifiman HE-4XX / Beyerdynamic DT880

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Offline DSatz

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Anyone? Yes, I've seen one such claim--a vendor who boasts about the noise on his DC supply being so low that it's in the small numbers of microvolts.

However, I think that was both misplaced perfectionism and an appeal to the ignorance of his readers. The whole premise of a balanced input configuration is that it suppresses any noise that appears in like amplitude and phase on both modulation leads. The DC for a phantom power supply only has to be reasonably well filtered; the balanced input circuit should then be able to suppress any common-mode noise in the supply voltage by 80 - 100 dB or so, just as it suppresses other common-mode noise in the microphone and cable.

Of course, this requires good actual circuit balance at the frequency of the offending noise. For this reason, the match between the two phantom "feed" resistors on each channel is specified in the DIN standard to be 0.4% or better. This is a narrower tolerance than the absolute value of the resistors themselves, and more critical than the 1% precision that many people use. An arbitrary pair of 1% resistors can differ in value by as much as 2% (worst case), which would limit the ability of the balanced input to suppress common-mode noise. And not just noise from the phantom supply, since those resistors are in parallel with the preamp input. This puts them in a position to disrupt the balance of the entire circuit between the microphone and the input.

I know of one preamp manufacturer, highly respected among classical music engineers, who selects 6.8 kOhm resistor pairs to be within one Ohm of each other on any given channel. That's probably beyond the point of diminishing returns, and resistor values can drift somewhat over time anyway, but I still appreciate his care. Microphone manufacturers need to take similar care when selecting components for their output stages, and the better ones do.

Other than that, phantom supplies just need to supply phantoms of the proper shape and size, and not run out of them ...

--best regards
« Last Edit: September 06, 2018, 09:01:51 PM by DSatz »
music > microphones > a recorder of some sort

Offline Popmarter

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Given that some believe Millard used a wheelchair to record



I met a (the) guy who pushed his wheelchair in to many of the 70's Zepp shows...and he had all the 1g tapes from Mike (red/blue rollerball ink, "Mike The Mic" written on each spine....and many on VHS!) to prove it.


there was basically no other way to get that deck into the venue....for Zeppelin, they wheeled him right up into the front handicapped section...I think there was deck problems with one of the '75 shows (Long Beach?), which is why it's truncated.

I have one of his last masters (as a 2g), sadly, it's an ABB show from the Greek in '90 or '91 (not at home to check), so it's not really torrentable. Dave (wheelchair pusher) let me sit in his house for 4 days and dub down whatever I wanted....


will send you a PM, as I think the wheelchair pusher is still active occasionally on TTD. I also have his ex-wifes phone number/FB info, so I may be able to track him down that way.

well, pics or it did not happen! :)

Man, this great story needs some new first hand info on Mike!
Currently in use:
Recorders: Edirol R44, Sony M10 & Sony D6
Microphones: Milab VM-44 Links (cards), AT853 (cards) & Nakamichi CM300 (all CP-s)
Preamps: JK Laboratories DVC-X-17b, Naiant IPA & Nakamichi MX-100 modded for 9v battery use
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Offline Popmarter

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I'll confirm the information in the thread; I used a 550 to record in Europe in 1974-75 before switching to a Sony, and AKG C 451s were my first real condensers back in about 1971. The wide-range, peak-reading meters on the Nakamichi were wonderful, and the mike preamps, though their inputs weren't balanced, were excellent. The original C 451 cardioid was on the bright side sound-wise; not harsh, but definitely not neutral/natural sounding. The omni for that series, on the other hand, was rather sweet for semi-distant recording.

When I was actively using the 550 I was already using Schoeps mikes, and I had an outboard battery supply built for them, with unbalanced outputs. I wished that I could modify the deck to add input transformers and 12-Volt phantom powering (or 10-Volt, since as I recall that was the recorder's positive "rail" voltage). IIRC the 550's input sockets were the tip-ring-sleeve type, so they wouldn't have needed replacing--but there wasn't enough room for transformers inside the case.

--Do people here know that Nakamichi during that era still had its own EQ curve that was ~2 dB different on the high end from anyone else's? Cassettes recorded on a Nakamichi of this period played back a little dull on all other brands of cassette deck, while all cassettes sound brighter when played back on a Nakamichi of this era than any other brand. (Hifi salespeople would play your cassette on a Teac or Sony or Advent, then on a Nakamichi, and the tape would always sound a little clearer in the Nakamichi; therefore it was better.) Nakamichi eventually came much closer to matching the rest of the world, but that was years after the 550.

--There are variants of the original C 451 amplifier that you shouldn't reject out of hand if you find them. The C 452 was modified by the addition of one resistor so that the current draw at 48 Volts would be lower (without it, the mikes needed 6 mA each), but the compromise is that the C 452 can ONLY be powered by 48 Volts or thereabouts, not 9 to 54. The "EB" version (made for both the C 451 and C 452) is the same circuit as the "E" with the addition of a switchable low-cut filter.

BTW, the "E" stands for "export" and simply means that the amplifier has an XLR connector on it. At the time, the XLR hadn't achieved world domination yet, and microphones often had different output connectors depending on which country you were in. Tuchel connectors were still the main connector used in Germany and Austria, so the "continental" version of the amplifier is the C 451 C or simply C 451. I've also seen C 451 F microphones made for France, with Sogie connectors.

The Austrian state broadcasting network (ORF) required and used full-sized Lemo audio connectors on everything, both at mike and line level. AKG made the C 451 L for them--as a musician I remember being recorded with those. Inside the ORF's sound trucks, even their Studer decks were specially equipped with Lemo connectors for audio inputs and outputs. That way they only had to carry one type of cable for remote jobs--plus no one would be too tempted to steal the equipment for their own use, as with the "left-handed" light bulbs that are used throughout the NYC transit system.

--best regards

Interesting, very nice. Thank you. Some Nakamichi cassettedecks also carried a 'E', like for instance the CR-7(E) I own. I was told it stands for 'Europe', but 'Export' will do.
Currently in use:
Recorders: Edirol R44, Sony M10 & Sony D6
Microphones: Milab VM-44 Links (cards), AT853 (cards) & Nakamichi CM300 (all CP-s)
Preamps: JK Laboratories DVC-X-17b, Naiant IPA & Nakamichi MX-100 modded for 9v battery use
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Offline spyder9

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How about a Denecke PS-2?  Very nice sounding P48 supply and it runs on a 9V battery.  Very small footprint.  I know you're trying to get the exact sound, but why splits hairs at this point?  The Denecke is a low noise solution that doesn't color the sound.   My 2 cents.

Offline DSatz

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I hate to nag, but it sounds to me as if you people don't realize how much current the 451s draw when they're powered at 48 Volts. It's 5.5 to 6 mA per microphone, which is higher than almost anything else that people use nowadays. The microphones are from the earlier years of phantom-powered studio microphones. AKG was in Austria, not Germany, and they flatly violated the DIN standard of the time, which specified a maximum of 2 mA per microphone at 48 Volts.

The C 451 was really a 9-Volt microphone, capable of running on as low as 7.5 Volts. For the sake of compatibility with other professional equipment, its circuitry was protected internally for use with 48-Volt supplies, which may go up to 52 Volts. But the higher the supply voltage, the more energy is simply thrown away (converted to heat) inside the mike. When these mikes are run at 48 Volts, about 3/4 of the energy from the power supply is turned into heat, and doesn't enhance performance in any way.

The supplies that this person is said to have used (AKG B-46E) weren't 48-Volt supplies; see the schematic below. They didn't contain (as do the Neumann and Denecke supplies) an oscillator/voltage multiplier circuit that steps the 9 Volts of the battery up to 48 (always at less than 100% efficiency). Rather, the B-46E was a simple 9-Volt, linear supply for ONE microphone, and at that lower supply voltage, the mike used that power nearly four times as efficiently as it does at 48 Volts. So it was about a seven or eight times better arrangement, as far as the use of battery power was concerned.

JFTR, AKG's AC phantom supply for this microphone series, the N-46E, was also a linear 12-Volt phantom supply, not 48.

If you're being a purist about this historical re-enactment, you might also consider the fact that the B-46E had an output transformer built in to the case. That's how it blocked DC from reaching the input to which it was connected. I don't know the specifications of that transformer, but it may have had some effect on the sound quality.

I'm really sorry that I no longer own a pair of these supplies, or I would gladly have lent them to this project. But when I moved up to 12-Volt Schoeps mikes (CMC 3-- series), I wrote and asked the company if these supplies were compatible. The reply was positive, but I was told that the Schoeps mikes wouldn't be able to reach their proper maximum SPL with only a 9-Volt supply, so I retired the B-46s and eventually (if I recall correctly) discarded them.

[edited later to add:] I found a pair of B-46E supplies in apparent good condition, and have them here now. I will probably run some tests with Schoeps CMC 6-- mikes just to see what happens to the maximum SPL of the Schoeps when powered at only 9 Volts--but after that, the supplies will be available in case anyone else on the forum needs them.
« Last Edit: September 18, 2018, 09:27:17 PM by DSatz »
music > microphones > a recorder of some sort

 

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