EMRR
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Posts posted by EMRR
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Some of the old equipment, would be accurate. They made things in various plants all over the country. The original goal in the 1990's was reissuing the 300B, which they did. I don't know how long those have been gone, quite a while I think.
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This all reads like the same re-boot of a re-boot of a re-boot that's been doing various things since the mid 1990's. They surface, they disappear, they surface. Lots of 'new things coming' promises, very few making it across the line. I've been curious the whole time.
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Are the sonics of a 274 worth the expense at this point? It's hard to imagine, but I haven't heard one apples to apples either.
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12 hours ago, jhewes said:
Maynard - why would I hear the ringing just on the phono input? Are the 12AX7's part of the phono stage?
I'm not Maynard, but will add that in general the phono input should be higher gain than the others, so more prone to amplification of vibration.
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Typical to see larger gauge wire on low frequency drivers versus mids or highs. Power used by an amplifier is greater for lows.
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It's about the combo of voltage and current, not just voltage. A preamp compared to a power amp is a lower current device, though here we have a fairly high amount of potential current stored in the filter caps. If I were tech-ing around inside there, I'd probably add a bleeder, but I'm not advising you do so if it is at all out of your element to sort out. Follow the 'one-arm-behind-back' rule, and don't touch inside and outside the open unit with both hands if in doubt of what you're touching; prevents a path through the body. I wouldn't expect any difficulty if you are just cleaning pots.
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Downside is you may flush the remaining lubricants out, ideally you follow it with their fader lube. If washed totally clean, contact may be better but scratchiness may increase without a re-lube.
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I've had tubes in some stage performance amps for over a decade, no problems. A few have seen regular 2.5 hour gigs at fairly high volume.
If you hear the effect of the amp sitting on the speaker, then there's a definite problem. Compare, it may require that.
EL84 filaments are particularly bad for 'singing' audibly with vibration, many an instrument combo amp with EL84's have 'extra sonics'.
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Never said close to a 255A. Not sure where you get that.
They rebranded that entire line of Langevin pro audio preamps and power amps. The 660/670 limiter info, also pro audio, comes from the guy who designed it, brought it into Fairchild after the fact, then went on the be an exec at Ampex.
Anyway, I got us really off topic here. I'll bring more evidence as I find it. It may be more within the pro audio realm, which is what I pay most attention to.
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There's an enormous amount of stuff that can't be found with Google. Fairchild 621 is a Langevin 116A with a Fairchild sticker on it. Simple as it gets.
an ad:
Langevin 116A / Fairchild 621 shown
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Hi Sam,
I may be wrong, quoting sources from memory that I can't dig up at the moment. I'll keep digging.
Here's a few things:
The Langevin 116A / 117A amps were rebranded as Fairchild products with their own model numbers, a simple Fairchild decal overlay.
The 660/670 limiters were designed and licensed by Rein Narma who came on board afterwards, I believe somewhere in an interview he stated that at the time Fairchild Recording was more of a licensing house than a design/manufacture house. That may be a reference to earlier eras, and not representative of later eras, as Fairchild existed for many decades.Memory (possibly faulty) says one of the 50's consumer mono block amps was a rebrand, I can't recall the originating company.We have George Alexandrovich Sr who tells us he worked for Fairchild over 20 years and designed a lot of equipment, so that may indicate a turning point in the mission of the company. -
You can look at it from another angle: equipment left on 24/7 tends to fail whenever it is powered down, usually a power outage or UPS failure.
But. Tube gear is different, and I'd not waste the finite life of a vintage tube with constant power.
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Killing me! I'm less than 2 hours away, but really don't have the space. Trying to justify.....
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those have always sold fairly high on the used market.
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Good work! Very interesting to see these results.
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My recording studio monitors reveal all sorts of distortions and dirt that I can't hear on any other speakers (La Scala with CT125's included) or headphones.
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A Variac is a continuously adjustable power potentiometer. Meant for temporary use.
Here's a wider range version of what I was speaking of, though not the one you'd want, just as example. There are others with 5 volt steps that top out at 120V, where this example has some step-up capability and larger steps. All lack a ground connection, so you'd need to wire ground path around the unit. This is fixed power taps on an isolation transformer.
http://www.ebay.com/itm/Stancor-Line-Adjuster-Transformer-/332115872246
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Air Design was making pro audio transformers as far back as the 1940's, I've seen fully potted examples in broadcast equipment from them, they've sounded nice. Anything from an organ stands a better chance of having good full range response given the response requirements of the source. It's probably fine, assuming it's an output.
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I do repair work on the side, mainly tube gear, and have been hopelessly backed up for at least 5 years now. I usually don't take any new work, there's so much waiting to be done. I don't have many other contacts to refer people to, and the few I do trust as referrals are also usually backed up as well. I concur that the trend of diminishing options will continue and I have no answers. If I wanted to do repairs full time I could, and probably also hire people. Audio repair work is a high-burnout field, and I can think of at least a dozen guys regionally who did audio repairs full time for a few years and all walked away from it.
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whatever you do, the point is minimizing motion between the base and the glass so the leads don't break.
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Nice find!
Fairchild as an audio company, to my understanding, did not design much of anything, with most of their products being either licensed/purchased designs or re-brands such as stock Langevin amplifiers with different tags. Possibly an early adopter of that approach.
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1st thing always is to excercise/clean the sockets by pulling and reseating the tubes. Contact resistance builds over time and easily causes noise in high impedance environments. Many vintage broadcast equipment manuals recommend this on a seasonal basis as preventive maintenance.
Of course it may may be something more serious, but this first.
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You would do that. Any sort of high temp sealant you can get in the crack, or double down and de-solder all 4 pins at their ends (they are hollow tubes) and pull the phenolic socket loose from the leads, fill with sealant of choice, then re-seat and re-solder the leads.
If not too loose, just leave it alone. Invasive procedure maybe more harmful than ignoring.
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I'm not at all saying or implying it can't work. Really, it's more of a case of speaking different languages and having different customs, making one sided observations in an attempt to share POV and get some feedback, bridge the gap if possible. If anything, I'm suggesting it's possible you are creating a personal remix that serves your ears and systems, as much as 'correcting' anything mastering ever did. Nothing wrong with that.
Makes sense on thread veer. I've started working through those.
One bit in my lost post concerned room EQ. I occasionally run IK Multimedia ARC2 room correction EQ. It sounds incredibly weird, and if used has to be on for all of the session. You can't turn it on and off without disorienting yourself. It can't be used while recording because it's not something that can be placed inline as natural flow, and if flow was adjusted to do so, you'd still have system latency disturbing musician timing. It's really only good for spot checks and mixing. I tend to leave it off more than on these days, as a natural room sound interacting with personal knowledge of room translation generally serves better. I don't believe I have plots available, as the setup process is automatic. Studios generally seem to be split between those that use some sort of room correction EQ and tolerate the negative sonic aspects of the EQ, and those that don't in favor of a better sounding system which they have to drive through learned muscle memory (long process).
I run Spectrafoo Complete for assessing input channel responses, particularly low frequency instruments, and keep a Dorrough loudness meter on the mix output. Spectrafoo will let me take long response captures and compare plots, if testing equipment or comparing before/after from Mastering processing.
One mastering process I see occasionally involves EQ attention to the key of the music, turning down the ranges most unused so as to emphasize the note values most predominate in the arrangement. This is effective with rock and pop music in reducing mud and emphasizing immediacy/presence. If you think about the curve of any piece with regards to key, you would expect to see hills and valleys in response. As well the instrumentation and it's predominate harmonic spread will affect where energy lies. The turning down tends to be in the sub-1dB range, 2dB would be a lot unless there's a significant problem to correct in a mix. A few years ago I converted a broad curve Langevin program EQ from 2dB/step to 1dB/step for a mastering house that wanted tighter control. After conversion it's greatest possible change was +/-6dB. A lot of modern mastering EQ's have their range divided into 1/3rd dB steps with a fairly limited overall range.
This may interest you, external link about the effects of phase rotation on clipped signals. This in in a discussion about vinyl mastering equalizer design.
http://www.proaudiodesignforum.com/forum/php/viewtopic.php?f=6&t=828&start=20#p10016
PM coming.
A new EL34 tube design by Sophia Electric
in Talkin' Tubes
Posted
Thanks for pointing that out, interesting read. I've wondered about their tubes for a long time, haven't heard any. Their 45 is the only reproduction I'm aware of.