I picked up one of these ancient boxes to experiment with on a Part 15 or a carrier current AM box. I'm hoping I can find a schematic to have available so if I need to replace anything I'll know what the components are. Any help is appreciated.
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Wanted: Schematic for Harris ME-1 Modulation Enhancer
- Thread starter RadioMan203
- Start date
That's how I became familiar with it. The AM I engineered had one which was taken out of service when they went AM Stereo back in the mid-80's. I wanted to get their post-sunset transmitter (LPB TX20) to sound as close to the MW-1 as possible. I used the enhancer on the little LPB and it was as dense and loud as the main. At the studio, you'd hear the power switch and it sounded like nothing more change from a loudness standpoint.
REW: I sent you a PM with email info for the schematic. Thanks again for the assist.
REW: I sent you a PM with email info for the schematic. Thanks again for the assist.
I used an ME-1 on a Harris MW-50 and it did a great job or increasing the density. It didn't work too well on an RCA BTA-10H with traditional plate modulation. It increased the density but the distortion was objectionable. Probably due to the phase shift through the various audio transformers in the beast.
I would love a copy of the schematic. As I recall, it had a "floating" power supply so that it could control the balanced audio without the need for input and output transformers.
I would love a copy of the schematic. As I recall, it had a "floating" power supply so that it could control the balanced audio without the need for input and output transformers.
It's basically a clipper and produces square waves...and those big hunks of iron in plate modulated rigs don't pass square waves well at all. It may well sound good on a part 15 rig.frankberry said:
If someone comes up with the skiz, please let us know. But, really, it can't be all that complex. Probably a couple of reverse-biased diodes. 
That's what the supply would be for, to set the clipping thresholds.
That (and a couple of phase-corrected 5534s) was what was in the simple-yet-effective composite clipper I built for Z100. Of course with AM, unlike FM, asymmetric modulation is desirable, so the +/- thresholds have to be separately adjustable.
I'd be interested to see how the ME-1 accomplished this.
Kind Regards,
David
That's what the supply would be for, to set the clipping thresholds.
That (and a couple of phase-corrected 5534s) was what was in the simple-yet-effective composite clipper I built for Z100. Of course with AM, unlike FM, asymmetric modulation is desirable, so the +/- thresholds have to be separately adjustable.
I'd be interested to see how the ME-1 accomplished this.
Kind Regards,
David
Got it.
Thanks.
Thanks.
Giving credit where credit is due, it comes courtesy of Robert (rew) above.
David Reaves said:
Glad it found a good home. I only wish I had the foresight to copy the manual back when I had the box at my old AM gig.
David Reaves said:
I didn't notice - I'll have to check that out!
Gee David, Seeing that you work for TransLanTech makes me wish I could get myself one of those Ariane boxes (even the plain analog box) - too bad the only way I can afford one on my budget will be when they become as old as the ME-1.
Thanks for the tip. I was pretty happy with the stock results, but I may just try that to compare what it does. Although I never used the box on the MW-1 (it was already removed from service by the time I got to the station) it made the little LPB post-sunset box match the density of the main audio processing chain without having to reinvent the wheel.
The Amigo has a decently capable dual-band AGC and tri-band limiter, but for any AGC adjustments other than input level, you have to open it up and change jumpers on the circuit board -- not too convenient to do on-the-fly.Sgeirk said:
CRL's AGC also had something like 17 dB of headroom above the point at which the red front panel "OLVD" indicators would light, before it would actually clip. That's a lot of headroom you can use to your advantage to help tame wildly varying input levels, unlike digital processors in which there is no such "unadvertised" input headroom, and anything above the indicated maximum will clip.
And as for the Modulation Enhancer... it definitely isn't NRSC-compliant, and the clipping circuits in post-Volumax processors have made it obsolete anyway. If you need a "band-aid" for poorly performing AM processing, try adding on an Inovonics 222 or CRL SPF-300, either of which are designed to give you a bit of extra loudness while also bringing you into full compliance with the NRSC specs.
I had the first generation CRL AM Stereo processing system at the AM that had the MW-1 and the ME-1 enhancer. I found it sounded gritty when pushed to any sort of degree of loudness (the AM had been playing MOR before an ownership change, moving it to oldies). One of the boxes also developed an annoying intermittant that was difficult to trace out, so I took my personal Optimod 8000a and stuck it at the studio in place of all but the last CRL processor that fed the AM Stereo exciter. The sound became more dense without the grunge or grit it had.
Someone told me that all the black potted boxes in CRL gear are mostly diodes and such that, when removed, would make the system sound better. I never tricked out the boxes at my station and sometime after I left they got rid of that gear. When they finally went off the air they had a DAP 610 at the studio and a BL40 Modulimiter (I have no idea what they did to make it NRSC-compliant).
For the Part-15 AM I'm playing with (one for the high school I work at I just don't have anywhere near the budget for anything fancy like Inovonics gear. If I come across something like that I would put it on, but the ME-1 was cheap ... and I mean CHEAP - obviously because the only other thing it's good for by a licensed broadcaster is perhaps a rack mount chassis.
Someone told me that all the black potted boxes in CRL gear are mostly diodes and such that, when removed, would make the system sound better. I never tricked out the boxes at my station and sometime after I left they got rid of that gear. When they finally went off the air they had a DAP 610 at the studio and a BL40 Modulimiter (I have no idea what they did to make it NRSC-compliant).
For the Part-15 AM I'm playing with (one for the high school I work at I just don't have anywhere near the budget for anything fancy like Inovonics gear. If I come across something like that I would put it on, but the ME-1 was cheap ... and I mean CHEAP - obviously because the only other thing it's good for by a licensed broadcaster is perhaps a rack mount chassis.
The CRL black boxes are all passive components (resistors, capacitors, diodes) and determine the time constants. Removing them defeats the gain reduction. Aside from the black boxes (and a proprietary IC for their "Dynafex" noise reduction), CRL processors use all industry standard components, mostly TL072, NE5532, and LM13600 ICs.Bill DeFelice said:
For Part 15 AM, I would adjust the ME-1 to deliver as high of positive modulation as the transmitter can handle, while keeping negative modulation below -100%. Part 15 AM is not bound to the same modulation and audio bandwidth limits as licensed broadcast AM.
Kevin Tekel said:
It's been twenty years since I've had the covers off of CRL gear, so I'm going strictly by what I was told at the time (and from what I remember of those past conversations). That certainly makes sense (about the black potted modules) considering all the other companies that potted the time constant networks such as CBS and I think Orban as well. I do, however, remember someone mentioning people removing some elements of CRL internals to make them sound less gritty and distorted. I picked up an Amigo TV for the school's TV studio - I'll have to see if that's too new to have any of those components that were once spoken of.
Exactly my thoughts, since I want to be able to teach the students about how AM broadcasting had been prior to digital. While I know I can demonstrate these principals with a 'scope, I hope to rangle up an AM mod monitor to go in their studio, since the idea is to outfit their studio to resemble and work as close to an actual broadcast facility as possible.
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