millbank power pac: 8 ohm mod? |
Post Reply | Page <12 |
Author | |
ceharden
The 10,000 Points Club Joined: 05 June 2005 Location: Southampton Status: Offline Points: 11776 |
Post Options
Thanks(0)
|
Just spotted the fact that they have two secondaries. If you link them in parallel rather than series, you should in theory end up with an amp which can drive down to 12.5Ohms if I've got my maths right. Might even handle an 8Ohm load.
I suspect if they are classD, given your description of the transformer James, the output stages are running on quite low voltage but high current rails. Maybe you could measure them? |
|
studio45
Old Croc Joined: 16 October 2007 Location: United Kingdom Status: Offline Points: 3863 |
Post Options
Thanks(0)
|
but these are 200w so..[calculator moment]...six and a quarter 8 ohm drivers would be needed or...he could drive 3 16ohm comps a side pretty nicely i suppose! James I bet you have six matching 16 ohm comps in a biscuit tin down the back of your sofa get em in a box
|
|
Studio45 - Repairs & Building Commotion Soundsystem -Mobile PA
|
|
ceharden
The 10,000 Points Club Joined: 05 June 2005 Location: Southampton Status: Offline Points: 11776 |
Post Options
Thanks(0)
|
In my second post I did take into account the 200W rating.
|
|
studio45
Old Croc Joined: 16 October 2007 Location: United Kingdom Status: Offline Points: 3863 |
Post Options
Thanks(0)
|
Forum message timing confusion issues, your brain and fingers work quicker than mine :)
|
|
Studio45 - Repairs & Building Commotion Soundsystem -Mobile PA
|
|
ceharden
The 10,000 Points Club Joined: 05 June 2005 Location: Southampton Status: Offline Points: 11776 |
Post Options
Thanks(0)
|
Only this time, I regularly take ages over a post, click submit and find that several others have already answered the question!
|
|
james folkes
Old Croc Joined: 08 January 2005 Location: United Kingdom Status: Offline Points: 3064 |
Post Options
Thanks(0)
|
hmm, i love the maths of 100 volt lines, they occasionally caused me a significant headache when installing. anyway... the two secondaries are 50 volt tappings, even if i connect in parallel then i will still be stepping up quite a bit. the primaries are on very fat wire, i suspect that they are high current, low voltage type but i haven't had a chance to have a big look at it because the millbanks have been displaced by my monitor console which i am trying to coax into life for alchemy next weekend. there's channel cards everywhere... anyway, my latest cunning plan is to use one of the output transformers to step back down again! i can even start running turns in series if i need to mess with the voltage. reckon that should work pretty well... i ought to have a chance to look at it this weekend, but mr dda does take priority.james.
|
|
mardy hippy.
|
|
Jake_Fielder
Old Croc Joined: 08 October 2007 Status: Offline Points: 4231 |
Post Options
Thanks(0)
|
They have a transformer in them to step the voltage back down i believe, so they will be a normal impeadence,
Its just a way of efficiently taking the power where its needed, using thin wires
(i think im right...)
|
|
dayglosteve
New Member Joined: 21 December 2010 Status: Offline Points: 1 |
Post Options
Thanks(0)
|
Hi
I designed this product. Nice to hear your comments ! The output stage is a full bridge Class-D. as regards the transformer it isn't part of the low-pass filter. It has two primaries which are in parallel to minimise leakage inductance. Each however is in two halves with the protection current sense resistor in the middle.!! If you remove the transformer you won't have any short circuit protection but it will still work. The amp rail is only 24V DC so it will only swing 13Vrms into a Lo Z load. About 21 Watts in 8R, 42 watts into 4R. In the 100V line application the impedance looking into the transformer is about 0.8R - thus the 200W rating. the whole thing is over-engineered cos its Voice alarm so ahs to run full power sinewave at elevated temperatures until doomsday ! .. unless Hi-Fi kit ! |
|
service dept Steve
Old Croc Joined: 30 January 2010 Location: S.W.London Status: Offline Points: 2034 |
Post Options
Thanks(0)
|
Maybe one of the 12 volt boys might like some, couple of 12 v batteries and a couple of hundred good quality watts- who knows?
|
|
We are not "They", We are "The others"http://www.servicedept.co.uk -
|
|
MattStolton
Old Croc Joined: 04 September 2010 Location: Walthamstow Status: Offline Points: 4234 |
Post Options
Thanks(0)
|
AFAIK, when Millbank closed down, the intellectual property (i.e. the clever staff) started up two separate companies, Application Solutions Ltd and Baldwin Boxall. Baldwin Boxall carried on in the same vain, relays and diodes type stuff, whilst ASL went DSP. BB have now caught up to DSP. Baldwin Boxall may be able to get circuit diagrams for some of this stuff, as there early gear was similar, whilst some of the crew at ASL may have memory of it. Worth a phone call, as both are friendly companies to chat to. |
|
Matt Stolton - Technical Director (!!!) - Wilding Sound Ltd
"Sparkius metiretur vestra" - "Meter Your Mains" |
|
Johnamps
New Member Joined: 22 March 2014 Status: Offline Points: 5 |
Post Options
Thanks(0)
|
Which model of the Millbank amplifiers do you have ? |
|
Guests
Guest |
Post Options
Thanks(0)
|
Anyone know much about this one?
|
|
Post Reply | Page <12 |
Tweet |
Forum Jump | Forum Permissions You cannot post new topics in this forum You cannot reply to topics in this forum You cannot delete your posts in this forum You cannot edit your posts in this forum You cannot create polls in this forum You cannot vote in polls in this forum |