This is the way I normally run tests to isolate: Disconnect any mikes/interfaces. Use only the amp with a tuner; or if it's a combo reciever then just the reciever. Listen to all speakers. Clean? Sound? Then move on . Add any RCA based inputs. Check for distortion. Move on. Hook up mikes...test them. Clean? Move on...if not try a different mike. Mikes can vary, even the jack style may be different as previous setups may have a low z mike attached to a hi z connection or vice versa. Last if you're dealing with distortion using a phone line or music on hold feature, is to see if the interface box uses 110V ac to amplify, generally hum/distortion occurs due to the 2 prong or 3 prong grounding designs.....carry some 2 prong adaptors and isolate the amp 1st, then the phone line interface. Damon Brunger Telrad Electronics Fort Wayne IN ----- Original Message ----- From: "markbrock" <markbrock@xxxxxxxxxxxxx> To: <techassist@xxxxxxxxxxxxx> Sent: Friday, April 29, 2005 5:39 PM Subject: [TechAssist] Re: 70 volt line audio amp > Jim, I disagree, a dead short on the primary may cause a problem (a new > one shows almost short on the primary ) but wouldn't the secondary being > shorted, only show no output from the speaker, it has no influence on the > load or impedance that the amp sees, as I understand it there is only > ferrite between the two windings inside this transformer itself, with taps > at different intervals of the secondary coil to make up the wattage out. > the peavey mic I'm using on the aux input works fine until you hook up to > the plant system, so again, I'm almost sure that Sunday I'll find an > isolation transformer or impedance matching transformer in the ceiling that > is the grandfather to all of the ones down the line, I'll bet its primary > is open... almost sure of it....I'll know real soon and I'll let you know > brock > > Brock Electronics > R.R.4 box 237 > 5208 cr.3385 > Independence Ks. 67301 > 620-331-0235 > fax 331-7191 > > markbrock@xxxxxxxxxxxxx > Zenith*Philips*Peavey*Fender*Crate > we work on all brands,makes,models > of anything that plugs in the wall > ----- Original Message ----- > From: "becyn" <becyn@xxxxxxxxxx> > To: <techassist@xxxxxxxxxxxxx> > Sent: Friday, April 29, 2005 12:39 PM > Subject: [TechAssist] Re: 70 volt line audio amp > > > > Mark, > > As a matter of practicallity, I personally never found some open/short > > condidtion > > down the line to be the problem (although a dead short on a tap seconday > > could do it). > > > > Did you try the mike instead of the output from the phone sys? > > Also, you need to use a lower gain "aux" input instead of the the high > gain > > mic input, otherwise the input will be overdriven. > > There may me some mismatch at the front end causing the distortion. > > Something about all this just doesn't ring true...sorry ;-) > > > > Jim McVey > > McVey Alltronix > > 327 Broadway > > Newburgh N.Y. 12550 > > > > "If it doesn't play... > > CALL MCVEY !!!!!!" > > Factory authorized > > service for over 20 > > major brands. > > 845 561 8383 > > (Last of the Mohegans) > > > > markbrock wrote: > > > > >Yes Jim, I'm hooking up to the 70 volt line port. these amps have a > remote > > >feature, the phone is used as a paging system, this amp is to drive the > > >speakers on the lot and in the shop and wash basin and paint booth and > show > > >room, ( car agency ), there is an auxiliary control for back ground > music, > > >cd, tuner, etc, the phone company controls the music on hold through a > > >different system, this is just for PA purposes only, > > > now back to the original question and I agree with J Silverman, > these > > >systems can be checked with an ohm meter, and 70 ohms is too high, > there's > > >and open tap somewhere, 15 foot on the ceiling I suspect to find an > > >impedance matching transformer, ( like peavey builds ) where you can > > >basically hook up a short or what ever but right before the amp sees it > its > > >isolated by a large transformer, and I strongly suspect when the output > > >shorted and the filter caps blew, it crammed dc directly into this > > >transformer and opened the primary, I'm probably getting enough leakage > > >through it from the eddy urrents that fly around the outside of the 70 > volt > > >signal. thats my best guess I'll see Sunday when I tear up the ceiling > of > > >those nice offices and make my accent to the roof..... man I can't wait. > > >I'll let you all know. thanks for the help so far. > > >brock > > > > > > > > >Brock Electronics > > >R.R.4 box 237 > > >5208 cr.3385 > > >Independence Ks. 67301 > > >620-331-0235 > > >fax 331-7191 > > > > > >markbrock@xxxxxxxxxxxxx > > >Zenith*Philips*Peavey*Fender*Crate > > >we work on all brands,makes,models > > >of anything that plugs in the wall > > >----- Original Message ----- > > >From: "becyn" <becyn@xxxxxxxxxx> > > >To: <techassist@xxxxxxxxxxxxx> > > >Sent: Thursday, April 28, 2005 5:26 PM > > >Subject: [TechAssist] Re: 70 volt line audio amp > > > > > > > > > > > > > > >>I'm going to ask a stupid question. > > >>Does the "new amp" have a 70v port output? > > >>If you are hooking up an 8 ohm system to the 70v , > > >>you will have a MAJOR impedance mismatch. > > >>Essentially, the 70 v is the audio version of the power grid. > > >>Step up the voltage( reduce current) to send long distances in order to > > >>reduce > > >>I^2 *R losses. > > >> > > >>Jim McVey > > >>McVey Alltronix > > >>327 Broadway > > >>Newburgh N.Y. 12550 > > >> > > >>"If it doesn't play... > > >>CALL MCVEY !!!!!!" > > >>Factory authorized > > >>service for over 20 > > >>major brands. > > >>845 561 8383 > > >>(Last of the Mohegans) > > >> > > >>J Silverman wrote: > > >> > > >> > > >> > > >>>70 ohms of resistance sounds high. Amps work into impedance, which is a > > >>>dynamic reflection of the load. DC ohms resistance should be much lower > > >>> > > >>> > > >than > > > > > > > > >>>the impedance number. Since that is a 70 volt line output, the DC load > is > > >>>just the resistance of the transformer windings. > > >>>Jerry Silverman > > >>>Greentron Inc > > >>>4 Newland Ave > > >>>Greenville SC 29609 > > >>>Fax/Phone 864 232 3889 > > >>>mail to: greentron@xxxxxxx > > >>>----- Original Message ----- > > >>>From: "markbrock" <markbrock@xxxxxxxxxxxxx> > > >>>To: <techassist@xxxxxxxxxxxxx> > > >>>Sent: Thursday, April 28, 2005 2:43 PM > > >>>Subject: [TechAssist] Re: 70 volt line audio amp > > >>> > > >>> > > >>> > > >>> > > >>> > > >>> > > >>>>brand new amp, works fine with one speaker and a mic, on the bench, > but > > >>>>when attached to the phone system, has distortion, I tried to blame > it > > >>>> > > >>>> > > >on > > > > > > > > >>>>the phone co because if I disconnected them it worked ok with one > > >>>> > > >>>> > > >speaker, > > > > > > > > >>>>no there pointing back at me, I need more ammo before I go further, > > >>>> > > >>>> > > >wish > > > > > > > > >>>> > > >>>> > > >>>I > > >>> > > >>> > > >>> > > >>> > > >>>>had a spare amp to try out. old amp has blown output ic and one of > the > > >>>> > > >>>> > > >>>> > > >>>> > > >>>two > > >>> > > >>> > > >>> > > >>> > > >>>>filters popped its lid, I was just wondering if this 70 ohms of > > >>>> > > >>>> > > >>>> > > >>>> > > >>>resistance > > >>> > > >>> > > >>> > > >>> > > >>>>was going to be way off base , but apparently doesn't surprise > anybody > > >>>> > > >>>> > > >>>> > > >>>> > > >>>yet, > > >>> > > >>> > > >>> > > >>> > > >>>>so I'll go a little farther. > > >>>>Brock Electronics > > >>>>R.R.4 box 237 > > >>>>5208 cr.3385 > > >>>>Independence Ks. 67301 > > >>>>620-331-0235 > > >>>>fax 331-7191 > > >>>> > > >>>>markbrock@xxxxxxxxxxxxx > > >>>>Zenith*Philips*Peavey*Fender*Crate > > >>>>we work on all brands,makes,models > > >>>>of anything that plugs in the wall > > >>>>----- Original Message ----- > > >>>>From: "becyn" <becyn@xxxxxxxxxx> > > >>>>To: <techassist@xxxxxxxxxxxxx> > > >>>>Sent: Thursday, April 28, 2005 9:43 AM > > >>>>Subject: [TechAssist] Re: 70 volt line audio amp > > >>>> > > >>>> > > >>>> > > >>>> > > >>>> > > >>>> > > >>>>>Divide and conquer ! > > >>>>> > > >>>>>Have you bench tested the amp with a 1Khz sine? > > >>>>>It sounds more like the amp than the line. > > >>>>>Many of those mutiple speaker setups have the taps set for a > > >>>>>watt or less, so underpowering isn't an issue. > > >>>>> > > >>>>>Jim McVey > > >>>>>McVey Alltronix > > >>>>>327 Broadway > > >>>>>Newburgh N.Y. 12550 > > >>>>> > > >>>>>"If it doesn't play... > > >>>>>CALL MCVEY !!!!!!" > > >>>>>Factory authorized > > >>>>>service for over 20 > > >>>>>major brands. > > >>>>>845 561 8383 > > >>>>>(Last of the Mohegans) > > >>>>> > > >>>>> > > >>>>> > > >>>>> > > >>>>>markbrock wrote: > > >>>>> > > >>>>> > > >>>>> > > >>>>> > > >>>>> > > >>>>>>ok, whats the limit of resistance I can have at the amp using a 70 > > >>>>>> > > >>>>>> > > >>>>>> > > >>>>>> > > >>>volt > > >>> > > >>> > > >>> > > >>> > > >>>>>>line, I have around 70 ohms, unit is very distorted, 40 watt > system > > >>>>>> > > >>>>>> > > >>>>>> > > >>>>>> > > >>>>about > > >>>> > > >>>> > > >>>> > > >>>> > > >>>>>>15 speakers, old unit burned up, they bought a new one and its all > > >>>>>>distorted, then they called me, I figured someone hung a regular > > >>>>>> > > >>>>>> > > >>>>>> > > >>>>>> > > >>>>speaker > > >>>> > > >>>> > > >>>> > > >>>> > > >>>>>>on the line but that would be closer to 16 or less ohms, is 70 ok > ? > > >>>>>> > > >>>>>> > > >>>>>> > > >>>>>> > > >>>>they > > >>>> > > >>>> > > >>>> > > >>>> > > >>>>>>may be under powered but it worked fine for 10 years previous. > thanks > > >>>>>>brock > > >>>>>> > > >>>>>>Brock Electronics > > >>>>>>R.R.4 box 237 > > >>>>>>5208 cr.3385 > > >>>>>>Independence Ks. 67301 > > >>>>>>620-331-0235 > > >>>>>>fax 331-7191 > > >>>>>> > > >>>>>>markbrock@xxxxxxxxxxxxx > > >>>>>>Zenith*Philips*Peavey*Fender*Crate > > >>>>>>we work on all brands,makes,models > > >>>>>>of anything that plugs in the wall > > >>>>>> > > >>>>>> > > >>>>>> > > >>>>>> > > >>>>>> > > > >>>------------------------------------------------------------------------- > - > > >>> > > >>> > > >- > > > > > > > > >>>>-- > > >>>> > > >>>> > > >>>> > > >>>> > > >>>>>>This Email List is Public. Remove: > > >>>>>> > > >>>>>> > > >>>>>> > > >>>>>> > > >>>http://www.tech-assist.org/remove.htm > > >>> > > >>> > > >>> > > >>> > > >>>>>>Lost Password: http://www.tech-assist.org and select "Login > > >>>>>> > > >>>>>> > > >>>>>> > > >>>>>> > > >>>Problems?". > > >>> > > >>> > > >>> > > >>> > > >>>>>>Appliance Repair List: > > >>>>>> > > >>>>>> > > >>>>>> > > >>>>>> > > >>>>http://www.tech-assist.org/secure/tip/chatjoin.htm#app > > >>>> > > >>>> > > >>>> > > >>>> > > >>>>>>Email Archives: //www.freelists.org/archives/techassist/ > > >>>>>> > > >>>>>> > > >>>>>> > > >>>>>> > > >>>>>> > > >>>>>> > > >>>>>> > > >>>>>> > > >>>>>-- > > >>>>>No virus found in this outgoing message. > > >>>>>Checked by AVG Anti-Virus. > > >>>>>Version: 7.0.308 / Virus Database: 266.10.4 - Release Date: 4/27/05 > > >>>>> > > >>>>> > > >>>>> > > >>>>> > > >>>>> > > > >>>------------------------------------------------------------------------- > - > > >>> > > >>> > > >>>>--- > > >>>> > > >>>> > > >>>> > > >>>> > > >>>>>This Email List is Public. Remove: > > >>>>> > > >>>>> > > >http://www.tech-assist.org/remove.htm > > > > > > > > >>>>>Lost Password: http://www.tech-assist.org and select "Login > > >>>>> > > >>>>> > > >Problems?". > > > > > > > > >>>>>Appliance Repair List: > > >>>>> > > >>>>> > > >>>>> > > >>>>> > > >>>>http://www.tech-assist.org/secure/tip/chatjoin.htm#app > > >>>> > > >>>> > > >>>> > > >>>> > > >>>>>Email Archives: //www.freelists.org/archives/techassist/ > > >>>>> > > >>>>> > > >>>>> > > >>>>> > > > >>>------------------------------------------------------------------------- > - > > >>> > > >>> > > >>>> > > >>>> > > >>>--- > > >>> > > >>> > > >>> > > >>> > > >>>>This Email List is Public. Remove: > http://www.tech-assist.org/remove.htm > > >>>>Lost Password: http://www.tech-assist.org and select "Login > Problems?". > > >>>>Appliance Repair List: > > >>>> > > >>>> > > >>>> > > >>>> > > >>>http://www.tech-assist.org/secure/tip/chatjoin.htm#app > > >>> > > >>> > > >>> > > >>> > > >>>>Email Archives: //www.freelists.org/archives/techassist/ > > >>>> > > >>>> > > >>>>-- > > >>>>No virus found in this incoming message. > > >>>>Checked by AVG Anti-Virus. > > >>>>Version: 7.0.308 / Virus Database: 266.10.4 - Release Date: 4/27/05 > > >>>> > > >>>> > > >>>> > > >>>> > > >>>> > > >>>> > > >>> > > >>> > > >>> > > >>> > > >>> > > >>-- > > >>No virus found in this outgoing message. > > >>Checked by AVG Anti-Virus. > > >>Version: 7.0.308 / Virus Database: 266.10.4 - Release Date: 4/27/05 > > >> > > > >>-------------------------------------------------------------------------- > > >> > > >> > > >--- > > > > > > > > >>This Email List is Public. 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Remove: http://www.tech-assist.org/remove.htm > Lost Password: http://www.tech-assist.org and select "Login Problems?". > Appliance Repair List: http://www.tech-assist.org/secure/tip/chatjoin.htm#app > Email Archives: //www.freelists.org/archives/techassist/ > > > > -- > Internal Virus Database is out-of-date. > Checked by AVG Anti-Virus. > Version: 7.0.308 / Virus Database: 266.10.2 - Release Date: 4/21/2005 > > ----------------------------------------------------------------------------- This Email List is Public. Remove: http://www.tech-assist.org/remove.htm Lost Password: http://www.tech-assist.org and select "Login Problems?". Appliance Repair List: http://www.tech-assist.org/secure/tip/chatjoin.htm#app Email Archives: //www.freelists.org/archives/techassist/