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bss epc 740/780

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Topic: bss epc 740/780
Posted By: jonminns
Subject: bss epc 740/780
Date Posted: 08 August 2009 at 5:17pm
Afternoon all

I don't know much about these amps, i've seen pics of them around here a while back but searching turns up no results

Are they particularly heavy? What's reliability, power etc like, must be 10 years old?

I remember seeing a picture of someone using a 780 to run x1s

Cheers

Jon



Replies:
Posted By: JaKe
Date Posted: 08 August 2009 at 6:07pm
have you tryed searching the forum, there has been some discussions on these in the past.
My opinion is they are nice amps but not the most reliable.
First made about  20 years ago IIRC.
Brit Row had shed loads for their turbo rigs.


Posted By: james folkes
Date Posted: 08 August 2009 at 7:18pm
the electrical power converter series of amplifiers were, at the time of making, some of the most ambitious pa amplifiers ever built. packed with innovative technology, there is an awful lot of stuff crammed into those 2u chassis, they do indeed weigh a ton too. there aren't that many people who even know how, let alone enjoy repairing them, but i totally lust after them nevertheless. i wanted to get a pile for the martin modular rig from brit row, but they'd all gone before i got the cash together.

by modern standards they aren't insanely powerful, a bit over 1k a side into four ohms for the 780, but the spec is absolutely off the charts compared to almost anything you can buy today (like damping factor >1800), they control cones very well. at lower power levels they operate at pure class a topology, but then gets to class a-b as it gets above 20 something watts a side. as suitable for the studio as they are for the stage, they even come with a fan defeat switch to keep them hush-hush, no worries about overheating though as they have excellent protection circuits and you can keep an eye on the temperature with handy gauges on the front. behind the electrostatically charged dust filters you'll find little switches that configure the protection systems for 4 or 2 ohm usage.

when they were released a hi-fi magazine tried some out to see if the claim that a pa amp was suitable for the studio could possibly be justified, the verdict was: sell everything else, buy bss epc!

the manual is available from the bss website, it makes great reading. well, i think it makes great reading, but then again i do read operating manuals as a leisure activity.

james.


-------------
mardy hippy.


Posted By: studio45
Date Posted: 08 August 2009 at 7:37pm
I have 2 of brit row's old epc780's since 8 months now of almost weekly gigs, running sub at 2.66 ohms a side/lo mid at 8 ohms, i've had no issues and the sound is nice. Can't wait to get 2 more sub bins and unleash the 2 ohm power frankly!
things to know:
1. no bridge switch and external bridging isn't reccomended due to independent power supply design
2. they are deeper than standard rack cases
3.Microcontroller in power supply will stop amp turning on at all if anything is wrong, this can be a pain in the arse if it happens unexpectedly. Includes shorted outputs and worn out fans etc.
4. shorted outputs: also note the heatsink coils just inside the rear vents are live when the amp is on and an errant strand of speaker wire can cause a small bang and the amp to go into protect. As i found out :) No damage though, protection system works
5. the psu's can be switched for 2 ohm or 4 ohm operation - the 2 ohm setting lower voltage rails a little in exchange for more available current. running always on the 2 ohm setting causes the amps to get warmer. however the handy temperature gauge will let you know if it's too hot.

I did meet one old monitor engineer who used racks n racks of them for oasis tours mid 90s. He said they toured with a BSS tech. The reason he gave was the power supply issue - if one wouldn't turn on one day it was given to the tech to get repaired for the next show. Apparently this was common enough to make it worth the tech being on the tour! Hasn't happened to me yet though and mine are just in a basic rack sleeve, not much portection, get chucked in vans a lot.....


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Studio45 - Repairs & Building Commotion Soundsystem -Mobile PA


Posted By: djeddie
Date Posted: 08 August 2009 at 9:39pm
Was offered some of these for my F2 rig. Decided to stick with my SR707 and PPX's as they were lighter to lift! Bloody nice amps though. I'm off to eat some spinach and see if they're still up for grabs.

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Chas n Dave : it's like Drum and Bass but with beards.             E=mc² ±3dB


Posted By: andyamp
Date Posted: 08 August 2009 at 10:03pm
are they mos fet?

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a wise man changes his mind a fool does not.
http://www.matrixamplification.com/ - http://www.matrixamplification.com/


Posted By: studio45
Date Posted: 08 August 2009 at 10:41pm
Originally posted by james folkes james folkes wrote:

tbut the spec is absolutely off the charts compared to almost anything you can buy today (like damping factor >1800), they control cones very well. 
i actually noticed this. when the amp is off, 18" cones bounce and go boing when tapped. when amp is on, they go rock solid. first time i noticed i assumed i'd toasted a coil and came near to ripping the cone out to have a look! class a kicks arse


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Studio45 - Repairs & Building Commotion Soundsystem -Mobile PA


Posted By: shagnasty
Date Posted: 09 August 2009 at 1:54am
I think I posted this when someone else bought a few a wile ago, but, just in case... Rear racking is not optional on these beasts, they are very well made but 30KG plus of amp swinging on a 2U panel will trash it big style... Make sure you have the proper rack strips at the back to bolt the babies to!
 
Not putting more than 4 in a rack is a plan as well unless you have a forkilift!!
 
Smile


Posted By: Dave M
Date Posted: 09 August 2009 at 9:19am
EPC 780 weighs 25kg, mostly contructed using 2mm and 1.45 steel plate. Power is 1000W 4Ohm, 1500W 2 Ohm - copper heat sinks with biscuit fans, MOSFET output stage (IRF740s I think). Dual switch mode power supplies, The EPC760 where optimised for high frequency reproduction.  The last few made left the BSS factory at Potters Bar around 1995. I modified at least a 100 as BSS still came up with fixes for problems up until aroung 1999. The guy aound is to repair and maintain these amp is George M of DBA based in Baldock, he is the ex BSS service engineer and has exensive knowledge of these amsp and has some spares whcih inlude graded MOSFETS. I really liked these amsp and owned a few, i thought these amps sounded great and mine never missed a beat - fitting the correct fan filter material helps keep em cool and these need washing out often!

Cheers  Dave


Posted By: TRE4U2NV
Date Posted: 09 August 2009 at 1:05pm
GEORGE ClapHug

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IM SO SECRETIVE BUT I CANT TELL YOU WHY


Posted By: Dr T
Date Posted: 20 September 2009 at 5:25pm
Afternoon to everyone, just a "newbie" on here , but long in thr tooth otherwise.
I like to spend my "free time" fixing dead amps for the challenge of it, between lugging the working ones in ands out of gigs. So here's a plea fromthe heart, I've read up what i can on the EPC 780, I'd like to fix the one that was donated to me, any suggestions for where i might get technical info/circuit diagrams, or am i just wasting my time?

Dr T


Posted By: Phil B
Date Posted: 20 September 2009 at 8:46pm
As said before on this thread...contact George M


http://www.dba-uk.co.uk/

.p.


-------------
Mostly harmless.... except if catering is shut.

Solar Sound System Shennanigans.. http://diyhifi.biz/" rel="nofollow - http://diyhifi.biz/


Posted By: Marko
Date Posted: 21 September 2009 at 11:20am
Originally posted by james folkes james folkes wrote:


the manual is available from the bss website, it makes great reading. well, i think it makes great reading, but then again i do read operating manuals as a leisure activity.

james.


can you please pass a link, I'cant find anything...


Posted By: james folkes
Date Posted: 21 September 2009 at 1:25pm
Originally posted by Marko Marko wrote:

can you please pass a link, I'cant find anything...
 
err... i would do, only it appears to have gone missing for me too! odd that, i can't think of any good reason for removing it but i also can't imagine where else i might find have found it.
 
i'll see if it's on the hard drive of my machine at home.
 
james.


-------------
mardy hippy.


Posted By: 4D
Date Posted: 21 September 2009 at 4:30pm






These amps offer incredible savings on gym membership, though venues with narrow steep staircases even with the fittest of young men are best avoided.  




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DMZ. "The bass was intense. Girls were literally running up to stand next to the subs"


Posted By: Dr T
Date Posted: 21 September 2009 at 6:25pm
Firstly, that what i call a tower of power, reminds me of the problem of lugging Genie boxes up unsuitable stairwells in the late 70's.

Secondly, my email is pipahire@pipahire.plus.com

Any help is appreciated.

Thanks

Dr T


Posted By: 4D
Date Posted: 21 September 2009 at 7:51pm
sorted.. 

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DMZ. "The bass was intense. Girls were literally running up to stand next to the subs"


Posted By: djyves
Date Posted: 20 August 2010 at 11:20am
Will the epc 780(or 760) do 4r bridge into 2 subs running 40-121hz loaded with v18-1000?
epc780 does 1500w @ 2r per side, so 3000w into 4r bridge.


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"If brute force doesn't work, you're just not using enough!"


Posted By: shagnasty
Date Posted: 20 August 2010 at 11:44am
Check, but as far as I am aware the 780 don't do bridge due to psu limitations

Quite an expensive amp to blow up trying!



Posted By: djyves
Date Posted: 20 August 2010 at 12:13pm
Are they That expensive, just found one for less the 300 euro (witch is about 250gbp),
but does someone else claim the opposite, or not?


-------------
"If brute force doesn't work, you're just not using enough!"


Posted By: 4D
Date Posted: 20 August 2010 at 1:16pm
I have seen them running in bridged mode with a funny splitter lead on the inputs but as far as I know its not recommended....

250uk pounds is a good price for a superb piece of kit..


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DMZ. "The bass was intense. Girls were literally running up to stand next to the subs"


Posted By: djyves
Date Posted: 20 August 2010 at 3:57pm
I think the splitter lead was, to set one channel 180 degrees out of phase, so they could be used in bridge.

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"If brute force doesn't work, you're just not using enough!"


Posted By: djyves
Date Posted: 20 August 2010 at 3:59pm
does anyone have a manual, of a epc amp? I can't find them on the internet.

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"If brute force doesn't work, you're just not using enough!"


Posted By: Dr T
Date Posted: 21 August 2010 at 11:18am
I would say that getting 3000w bridged is a bad idea, as the power supplies are completely separate entities, and furthermore, the 4ohm/2 ohm switch function  reduces the power supply rails voltage (at 2 ohms) to prevent the whole thing cooking. Using the amps set to 4 ohm and bridged would be a bigger strain on the capacity of the output devices.  I am currently nurseing one of these beasts back to full health!


Posted By: Dr T
Date Posted: 21 August 2010 at 11:24am
Also i have a user manual pdf somewhere, when i find it i'll post it.


Posted By: 4D
Date Posted: 22 August 2010 at 1:54pm
ha

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DMZ. "The bass was intense. Girls were literally running up to stand next to the subs"


Posted By: Bob@DAE
Date Posted: 15 February 2011 at 2:23am
Hi,
I just bought a Turbosound Flashlight system with 5 amps (2 EPC760 & 3 EPC780)

I've been looking for the amplifiers manual on the web for several days.
Unfortunately, the link you posted above is out... Can you post an other link to download it ?

thanks !!!!!

Thumbs Up



Posted By: 4D
Date Posted: 17 February 2011 at 10:47am
Originally posted by Bob@DAE Bob@DAE wrote:

Hi,
I just bought a Turbosound Flashlight system with 5 amps (2 EPC760 & 3 EPC780)

I've been looking for the amplifiers manual on the web for several days.
Unfortunately, the link you posted above is out... Can you post an other link to download it ?

thanks !!!!!

Thumbs Up



removed for copyright infringement.. rather sad but true, pm me an email address and I will mail a copy.


-------------
DMZ. "The bass was intense. Girls were literally running up to stand next to the subs"


Posted By: mk2_ginger_biscuit69
Date Posted: 28 September 2013 at 9:39pm
Originally posted by james folkes james folkes wrote:

the electrical power converter series of amplifiers were, at the time of making, some of the most ambitious pa amplifiers ever built. packed with innovative technology, there is an awful lot of stuff crammed into those 2u chassis, they do indeed weigh a ton too. there aren't that many people who even know how, let alone enjoy repairing them, but i totally lust after them nevertheless. i wanted to get a pile for the martin modular rig from brit row, but they'd all gone before i got the cash together.

by modern standards they aren't insanely powerful, a bit over 1k a side into four ohms for the 780, but the spec is absolutely off the charts compared to almost anything you can buy today (like damping factor >1800), they control cones very well. at lower power levels they operate at pure class a topology, but then gets to class a-b as it gets above 20 something watts a side. as suitable for the studio as they are for the stage, they even come with a fan defeat switch to keep them hush-hush, no worries about overheating though as they have excellent protection circuits and you can keep an eye on the temperature with handy gauges on the front. behind the electrostatically charged dust filters you'll find little switches that configure the protection systems for 4 or 2 ohm usage.

when they were released a hi-fi magazine tried some out to see if the claim that a pa amp was suitable for the studio could possibly be justified, the verdict was: sell everything else, buy bss epc!

the manual is available from the bss website, it makes great reading. well, i think it makes great reading, but then again i do read operating manuals as a leisure activity.

james.



looks like someone has been stealing your words James!!

http://www.ebay.co.uk/itm/BSS-epc780-amplifier-4-2-ohms-/330921325379" rel="nofollow - http://www.ebay.co.uk/itm/BSS-epc780-amplifier-4-2-ohms-/330921325379

sorry for the bump, been shopping for one to play with....


-------------
''Remember that the object of a subwoofer is to enhance the output of your main speakers, not overpower it''

''Dubstep - an elongated electronic fart''


Posted By: madboffin
Date Posted: 29 September 2013 at 12:12pm
Quote when they were released a hi-fi magazine tried some out to see if the claim that a pa amp was suitable for the studio could possibly be justified, the verdict was: sell everything else, buy bss epc!


That's true, my ATC passive monitors sounded wonderful when I tried running them off an EPC780. A direct comparison with a Macrotech 2400... oh dear oh dear...



Posted By: SMP
Date Posted: 05 October 2013 at 8:55am
very nice kit run in class AB with a higher than usual bias so that they run in Class A mode for significantly more than the usual class B such as Labgruppen and others

Cannot remember now if it was fixed high bias or a sliding bias that was used. The other thing that is very different about these is the output stages most amps use a lesser amount of high wattage devices BSS turned it on it head and used lots of lower power devices this amongst other things has the benefit of reducing output impedance of said stage so improving Damping factor which is largely a product of the ratio of load impedance to output stage impedance as it contained lots of devices which in parallel exhibit a much lower value

it does have the disadvantage of giving you more of said devices to drive with there increased Gate capacitance but not difficult to address this issue though many other MOSFET it is a common
 issue not to address this at all the list for this is pretty endless  but C-Audio and many of that type are the culprits using Pseudo "class A" drive circuits to drive them so that cheaper transistors can be used and reliability increased but to the detriment of performance

Sadly very few audio designers fully grasped the principles of MOSFET use for high power Audio Amps but BSS and of course Adyton used them to good effect though the latter used them in a hybrid output stage (Bi-MOS)
so now we are mostly back to Bipolar devices as the impetus for MOSFET development was not continued for audio but they do many other tasks such as control the Motors on your Tube Train and many other power control tasks many SMPS contain MOSFET switching devices or it#s brother the IGBT such as QSC

perhaps i will have look at the service files think still have some on file at the old workshop jog my memories
but all in all super kit often ponder buying some for my collection of old amps coz they really were a wonderful ground breaking design



Posted By: madboffin
Date Posted: 05 October 2013 at 8:58pm
The power supply design was highly innovative too.


Posted By: Dave FFA
Date Posted: 07 October 2013 at 12:25pm
the amp was very innovative for the time. massively expensive to build - profit margin was almost zero for bss to build. if the amp is modified to latest spec these offer very high audio performance.. on going servicing is certainly an issue because of the skills and parts required.


Posted By: TRE4U2NV
Date Posted: 07 October 2013 at 12:43pm
Originally posted by Dave FFA Dave FFA wrote:

the amp was very innovative for the time. massively expensive to build - profit margin was almost zero for bss to build. if the amp is modified to latest spec these offer very high audio performance.. on going servicing is certainly an issue because of the skills and parts required.

+10000000000000


-------------
IM SO SECRETIVE BUT I CANT TELL YOU WHY


Posted By: SMP
Date Posted: 07 October 2013 at 1:09pm
Originally posted by Dave FFA Dave FFA wrote:

the amp was very innovative for the time. massively expensive to build - profit margin was almost zero for bss to build. if the amp is modified to latest spec these offer very high audio performance.. on going servicing is certainly an issue because of the skills and parts required.


Google+
Damn it Dave please STOP!!! You will have me searching for the Damn things relentlessly every waking moment! I must spend my time more wisely Like learning to Lay Bricks Apparently

Agreed definitely a "Loss Leader" for them but really think they were trying to capture a market that was very lucrative but alas eluded them

Damn it again Dave too late!!!....Does anyone know of any BSS EPC's up for grabs anything considered even broken, Sick or thoroughly abandoned in a Warehouse Corner somewhere feeling lost and rejected??? Well here at EPC Care we never put a unloved Amp down Your £3 a month will ensure that they have a happier life once again powering stacks of speakers or Flown Arrays they will even Write to you and you will receive a special soft toy and a wallchart when You join Justcall this Premium rate number Operators are waiting to take your call

LMFAOH time for Tea methinks nice one Dave


Posted By: Dave FFA
Date Posted: 07 October 2013 at 4:40pm
these amps are a big inspiration to me and I was lucky enough to help build the last ones that left the bss factory. I also modified countless qtys that belonged to brit row that used to come back to bss in their tour racks - I certainly learnt how to use a screw driver removing the front mounts and those lovely rear mounting plates. these buggers also ensured I was pretty fit too! I managed to build my own racks worth out of the remainder parts and a couple of used ones from Heath productions and used these with my TSE111 and TSE118s' in the 90's. unfortunately due to my utter stupid ness at the time these where stolen from me by some scum bag! If I didn't work for bss and c audio at the time this could of been the end of sound system for me. storm have some of these amps that maybe up for sale at a good rate. best regards Dave


Posted By: simonp1100
Date Posted: 07 October 2013 at 8:25pm
I am sure that the C-audio ones were designed around the ST range (using T03 FET's instead of the plastic K1058, J162) but with a switch mode power supply which was built by another company (came into them ready made / tested).


Posted By: Dr T
Date Posted: 13 October 2013 at 4:25pm
Hi I've been following the discussions re. the BSS EPC780. Well, I've a semi-working one that i no longer need or want. It is up from grabs for the cost of postage if anyone really wants one.
Dr T


Posted By: 4D
Date Posted: 13 October 2013 at 4:50pm
yep I will have it, pm'd you my details

or email me direct at

aa++4++dpa at yah+++oo.co.uk

removing the + & replacing the obvious at with @


-------------
DMZ. "The bass was intense. Girls were literally running up to stand next to the subs"


Posted By: SMP
Date Posted: 14 October 2013 at 12:54am
would have been nice, to add to my, "Museum" of such things.  But seems, got beat, to the post. still, been a good weekend all the same. One convert it seems from Function One to my kit. and Another who just wants some.and a convert from A.S.S. So You cannot win them all!!!! 


Posted By: 4D
Date Posted: 14 October 2013 at 9:29am
Apologies beating you to the post   Are they selling their Fk1, always on the lookout

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DMZ. "The bass was intense. Girls were literally running up to stand next to the subs"


Posted By: SMP
Date Posted: 14 October 2013 at 4:11pm
Not sure 4D I will Enquire I do Know they mentioned using Res 2 not sure how they work it either add mine to stock and keep both or complete changeover

BTW someone at gig last night the other FOH was talking about BPM show and some new kit on show saw pics had bass horns with holes in braces but NOT FK1   know anything?


Posted By: jacethebase
Date Posted: 14 October 2013 at 8:51pm
Originally posted by Dr T Dr T wrote:

Hi I've been following the discussions re. the BSS EPC780. Well, I've a semi-working one that i no longer need or want. It is up from grabs for the cost of postage if anyone really wants one.
Dr T


Where are you?

If it's till around I'm traveling up through the midlands tomorrow could collect?

Jace

-------------
www.wedding-production.co.uk

www.stage2sound.com


Posted By: nev23
Date Posted: 14 April 2015 at 12:32pm
Originally posted by Dr T Dr T wrote:

I would say that getting 3000w bridged is a bad idea, as the power supplies are completely separate entities, and furthermore, the 4ohm/2 ohm switch function  reduces the power supply rails voltage (at 2 ohms) to prevent the whole thing cooking. Using the amps set to 4 ohm and bridged would be a bigger strain on the capacity of the output devices.  I am currently nurseing one of these beasts back to full health!


I thought there was only one PSU for the pair of amplifiers?
And in any case, separate PSUs don't preclude or favour bridge mode. It doesn't make any difference.

The PSU was probably the most interesting aspect of these amps. A series resonant design. Never seen another like it.



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