fhawk618 10 Posted December 3, 2010 Share Posted December 3, 2010 First of all--thanks for letting me annoy you with questions. If I never ask--I'll never have the answers. I also have a couple of decades of experience that (hopefully) may be of use to someone else as well, so feel free to pick my brain (or what's left of it) as well. First annoying question is in regard to the Carver PM 1.5 amplifier. I have a bunch of these amps, and use them (as intended) for pro-audio/sound reinforcement applications, so I'm generally familiar with them. I recently acquired several of these amps that have two user-adjustable RMS output voltage adjustments on the front panel, next to the normal clip limiter (activate/defeat) switch. One is for a 1.5 sec limit and the other for a 30 sec limit with corresponding RMS output voltage adjustments. I purchased these amps from the original owner who had no idea what these controls were for, and stated that they had never been altered from the original settings (they are secured by locking nuts). So far, all that I've been able to determine (from the original Carver Users Manual) is that these controls were only present on the first 1000 units produced in 1983. There is no further discussion of their intended purpose or general function. Any input will be appreciated... Link to comment Share on other sites More sharing options...
kve777 6,681 Posted December 3, 2010 Share Posted December 3, 2010 Welcome! Can you post pics of these controls? I hope someone here can help. I have ideas, but will defer to experts. Link to comment Share on other sites More sharing options...
maddmaxxx 39 Posted December 3, 2010 Share Posted December 3, 2010 First annoying question is in regard to the Carver PM 1.5 amplifier. I have a bunch of these amps, and use them (as intended) for pro-audio/sound reinforcement applications, so I'm generally familiar with them. I recently acquired several of these amps that have two user-adjustable RMS output voltage adjustments on the front panel, next to the normal clip limiter (activate/defeat) switch. One is for a 1.5 sec limit and the other for a 30 sec limit with corresponding RMS output voltage adjustments. I purchased these amps from the original owner who had no idea what these controls were for, and stated that they had never been altered from the original settings (they are secured by locking nuts). So far, all that I've been able to determine (from the original Carver Users Manual) is that these controls were only present on the first 1000 units produced in 1983. There is no further discussion of their intended purpose or general function. Any input will be appreciated... -did not know that, hmmm -oh btw, WELCOME TO THE SHOW THAT NEVER ENDS , SO GLAD YOU COULD ATTEND Link to comment Share on other sites More sharing options...
Blues Pwr 765 Posted December 3, 2010 Share Posted December 3, 2010 Welcome to the forum, be patient and I'm sure somebody will come along with some ideas/thoughts on these amps, as previeously asked, pictures would be very helpful, anyways enjoy the forum...... Link to comment Share on other sites More sharing options...
zumbini 6,140 Posted December 3, 2010 Share Posted December 3, 2010 Howdy fhawk and welcome to the forum.Hope you enjoy you stay. I'm not familiar with the MP1.5, however, about 40 years ago I did sound reinforcement for theatrical productions. The house amps at the Candlelight Dinner Playhouse had similar adjustments for setting up the protection circuit. I don't recall the brand and don't remember adjusting them though. (We didn't push them anywhere near their limits.) Link to comment Share on other sites More sharing options...
RichP714 3,152 Posted December 3, 2010 Share Posted December 3, 2010 according to the service manual, the first 1000 PM-1.5 had front panel controls for setting the protection circuit's integrator threshold. With clipping eliminator, or 'soft clipping' network engaged, it's possible to send damaging rms voltages to the speakers without the normal symptoms of speakers stress (clipped highs, etc.) As the soft clipping network operates, it tends to compress the dynamic range of the signal, increasing the average level of the music, which can blow speakers. The integrator circuit samples the average power level over time; if you're stressing your speakers it will lower maximum power output. The service manual describes this ciruit and how it operates with clipping eliminator engaged. Remember those Onkyo amps that had servo controlled distortion feedback? sort of like rev limiters, you'd turn the volume up, and the amp would lower it again because distortion had exceeded 0.XX%.........I hated that. Evidently, the first few PM-1.5 had adjustable thresholds for the 1.5 second and 30 second trip levels. All moot points if you use other means to prevent clipping; there are better ways to limit dynamics than at the amp eh? 1 Link to comment Share on other sites More sharing options...
fhawk618 10 Posted December 3, 2010 Author Share Posted December 3, 2010 Thanks for the input so far--more is always welcome. I will post pictures as soon as I figure out the how on this site--shouldn't be hard. RichP714, your assessment is kind of what I had been kicking around--so the usefulness would be based upon the specifications of the specific drivers downstream. You could potentially maximize (or limit) the output of the amp based on the capabilities (or limitations) of the speakers being driven. If so, this also has the potential to be "a very dangerous game" based on the dynamic output capabilities of these amps--probably why these controls were deleted after the initial production run of 1000 units. Thanks to all for your input--anything additional will be appreciated. Link to comment Share on other sites More sharing options...
jldeni 439 Posted December 3, 2010 Share Posted December 3, 2010 Welcome fhawk, and thanks for posting your question. Sounds like many of us learned something new about the early 1.5 Link to comment Share on other sites More sharing options...
fhawk618 10 Posted December 3, 2010 Author Share Posted December 3, 2010 This may be one of those questions for Bob himself--"what were you thinking?" Link to comment Share on other sites More sharing options...
peck555 366 Posted December 4, 2010 Share Posted December 4, 2010 Welcome to the site. Link to comment Share on other sites More sharing options...
dokblues 101 Posted December 4, 2010 Share Posted December 4, 2010 WELCOME Fhawk!! Glad to see you over here! Link to comment Share on other sites More sharing options...
Guest Onangenman Posted December 4, 2010 Share Posted December 4, 2010 Welcome, These guys are full of good info. Link to comment Share on other sites More sharing options...
tanner 3 Posted December 5, 2010 Share Posted December 5, 2010 Greetings and welcome to the site. I just joined last week myself. I also use PM 1.5 amps for pro sound production. The oldest one I have is the same as the one you have, with the two RMS limiter controls on the front. The other four PM 1.5 amps are newer and do not have the limiter controls on the front. I do have a service manual for the amp. I will look and see if it has the instructions on how to set the controls. I have the owners manual for the amp and it describes how to set the controls. I have been looking for it since I joined the site but must have it buried under a pile of other manuals or schematics as I have not been able to locate it, but I haven't given up looking!! When I find it I will post the information. Good to see you here, its not often you run into anyone with multiple PM1.5 amps especially using them for sound reinforcement. Sure beats lugging 100 lb amps, LOL. Link to comment Share on other sites More sharing options...
tanner 3 Posted December 5, 2010 Share Posted December 5, 2010 Hi fhawk, I found a manual for the PM1.5 today. The manual is for the newer amps without the two limit adjustments on the front. I was sure I had the manual for the older type too, but cannot seem to locate it. I took a look at my amp and the two limiter adjustments are set as follows. The 1.5 second limit control is set at 11 oclock and the 30 second limit control is set at 10 oclock. I have been using this amp for over 20 years and it has always worked well and never fried any speakers, even though it has been driven hard at times. Hopefully the info I have provided will be of some assistance. I think the info Rich provided was correct and if one could find the proper manual for that particular amp, I think it explains in detail how to adjust the settings. I am not sure if that manual is here on the site or not. I for some reason haven't seen any owners manuals for the PM1.5 here on the site, but that might be just me, LOL. I'll keep an eye on this post, it interests me too. Have a great day!! Link to comment Share on other sites More sharing options...
RichP714 3,152 Posted December 5, 2010 Share Posted December 5, 2010 the manuals we have here don't cover that version of the PM-1.5. tanner, they can be found in two places. 1. the main page has a blue button that will take you to a list of downloadable manuals 2. the Library category has a database; they are under 'Amp Pro' Carver site! » Library » ----(DOWNLOADS) Equipment database (DOWNLOADS)---- » Equipment Database (Phase linear/Carver/Sunfire) (DOWNLOADS) Link to comment Share on other sites More sharing options...
tanner 3 Posted December 5, 2010 Share Posted December 5, 2010 Thanks for the info Rich. I did manage to find the owners and service manual with your instructions. I couldn't find them because I wasn't going to the Pro amp section. Thanks again. Going to start repairing my damaged amps hopefully next week. I will keep you posted. Fhawk PM me when you get a chance, I like to talk to other sound techs!! Later all. Link to comment Share on other sites More sharing options...
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