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Re: System Upgrade – Berkeley Alpha in the house

Posted: Sat Mar 16, 2013 9:02 pm
by RLRB
Sligolad wrote:I am out of the country for another week RLRB but when I get back next week I will send you scans of the manual.

Where did you buy your valves from?
Spoke with Tom Willis (the designer) by phone regarding a re-valve but Toms clock runs slower than mine and last time I spoke with him he was taking some time off and I agreed to get back to him one of these months when he is back in the saddle!!

Pearse.
hi, mine i bought with Siemens el34 NOS, ohhh God exists, the other i bought in ebay, i recommend GE 5751 the black plates 3 mica (less gain but superb, far better than Sylvanias 3m , miniwatt, etc), the RCA ecc82 are also very good.
One important thing, in Spain the current is 230 V and can legally vary (chnaged from 220 to 230 a few years ago), the amps were designed for 220 v and before i made a change the tubes were red glowing, i contacted with Sowter (of sowter transformers) and send me schematic to set the amps in 240 V and no more red glowing. it needs to open the amp and a little soldering, it worths, i dont know if you have this issue. this is very important. Do you have replaced caps?

thanks

Re: System Upgrade – Berkeley Alpha in the house

Posted: Sat Mar 16, 2013 10:15 pm
by Sligolad
Mine is a UK model so runs at 230 to 240v.
I use an AC regenerator with them which keeps the voltage at a steady 230v and removes all harmonics and junk from the AC supply.
Never did any work on them but I had been thinking of getting them back to Tom Willis for a service, maybe later this year!

Will have a look out for a pair of GE 5751 the black plates 3 mica tubes as they do sound like a good upgrade.

Re: System Upgrade – Berkeley Alpha in the house

Posted: Mon Mar 18, 2013 1:54 pm
by RLRB
Hi Sligolad

take a look at the back of the amps to be sure they are 230, i think they are 220 because they are from 1995¿?
the GE 3m Bp are becoming expensive, i bought 2 pair for 80 €, what a luck, mines are 5 star (i think aeronautical use).
do you have experienced red glowing, when i went to a technician, with a polimeter we got about 7,5 volt in heater with amps in 220v and 6.3v exactly with 240 volts, maybe your tubes are brand new.
the solution: the trafo has several winding and combining them (summing) you get the voltage required.
Mines are maestro I, as your i think, the input trafo on the right (tha maestro ii in left), mine with binding post near UL/TRIODE SWITCH, and without feedback switch, with a potentiometer on the right and without 3 pair of binding post to select 4 or 8,
in the same way i also have spec of output trafo to put in 4/8 ohm.
i think the guy who sold me doesnt knew what was selling, only the tubes cost what i paid for but had to go to technician due to some resistances. worth it
In my opinion they sound best (of course) in triode.
ah, mine doesnt have (i think the mk ii dont have) standy to the the filament warm.
the only think i dont like is that tubes are increasing in value, the new ones are not the same.
In comparison sylvania 5751 are most spatial more 3d image but the timbre is a little irreal.
DOnt get crazy and sell these beauties your ears will agreed (is this correctly written? dont speak from i was 18)

best regards