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Post by Chris on Mar 31, 2018 14:12:01 GMT
Just read a wee article there that extols the virtues of a border patrol outboard psu upgrade. I think I get the general gist of it but could someone please explain it all a wee bit better? From what I gather it replaces two rectifiers and makes a huge improvement to sound quality. Does it have to be border patrol or can or can I use another type? Could one be built by a keen diyer? Are the improvements that good? Heres the thing I'm on about.... www.users.globalnet.co.uk/~valveamp/BorderPatrolPS.htm |
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Post by MikeMusic on Mar 31, 2018 14:16:14 GMT
Manuel mode :
I know naarthing.
Tech knowledge required
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Deleted
Deleted Member
Posts: 0
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Post by Deleted on Mar 31, 2018 15:13:54 GMT
Just read a wee article there that extols the virtues of a border patrol outboard psu upgrade. I think I get the general gist of it but could someone please explain it all a wee bit better? From what I gather it replaces two rectifiers and makes a huge improvement to sound quality. Does it have to be border patrol or can or can I use another type? Could one be built by a keen diyer? Are the improvements that good? Heres the thing I'm on about.... www.users.globalnet.co.uk/~valveamp/BorderPatrolPS.htmI knew a guy who built his own transformers and made and serviced valve amps all his life. He didn't have a good word to say about Border Patrol. He completely rebuilt my Series 500 which I bought wrecked, so I have respect for his opinion. He was clearly of the view that you definitely didn't have to stick to Border Patrol to enjoy such add-ons. |
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Post by ant on Mar 31, 2018 15:42:57 GMT
It says that the add on psu is a choke input supply, most production valve amps these days are ss rectification, cap input, and crc (cap resistor cap) filtering so alot dont have a choke at all.
The choke adds a load of inductance to the psu, and valve rectification rather than solid state.
So. the advantages of this psu over what is common these days. a slow start as the valve rectifier heats up so the valves and caps arent hit with a large voltage overshoot from the instant ht an ss rectifier gives, a choke input supply which I think sounds better than cap input although I dont know why, probably something to do and smoother filtering. The choke will have a rubbish frequency response so wont let high frequency switching spikes from the rectifiers through to the following cap bank.
A current capability of 250ma may give larger headroom than the internal psu too, it depends what amp you are trying to upgrade. An se amp would probably benefit, a pp amp might not.
To be honest, the upgrade value would entirely depend on what amp you put on the end of it, but there are a couple of reasons why that psu could be an upgrade.
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Post by Chris on Mar 31, 2018 16:30:15 GMT
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Post by ant on Mar 31, 2018 17:51:58 GMT
I reckon the difference the reviewer hears is filtering. I dont think they have replaced the internal psu at all,just bypassed the ht winding on the mains tx and used the filter section after the rectifier. Probably All they have done is to put extra filtering infront of the internal psu.
Looks like its ended up as a clcl filter, and I would suspect that the choke in the BP module is a higher h than the internal one.
A pp 6550 amp will be pulling 220ma easily at idle, at least 50ma per power tube to get 30w out of it and say 20ma for the driver stage so there aint that much current in reserve for peaks.
They may have rebiased the power section too, autobias is probably cathode bias so is set by a resistor. They could have altered this to change the bias point to something better for output stage.
It could be running at a completely different voltage to the original, higher voltage and lower qc to get abit more current capacity out of the psu.
There is no way to tell and the reviewer obviously doesn't know the details.
It is completely irrelevant if it is made by border patrol or someone else, its a psu not a complete amp
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