|
|
Post by electronumpty on Jun 1, 2020 15:42:59 GMT
I use Tesla pcc88s no issues . You can order a pair fairly cheaply form eastern Europe on the bay. A stock build apart from Mundorf cap so pretty much to spec.
|
|
|
|
Post by firebottle on Jun 1, 2020 16:16:25 GMT
Hi Martin, I have sent the 8.2V zener and a 1 ohm resistor in the post this morning for you to try. I use a Telefunken PCC88, a russian 6N2P-EV and a Matsushita 7DJ8/PCC88. The Matsushita heater does look a little brighter than the other 2. I have just been looking at all the data sheets, La Radiotechnique, Philips, and Tesla show a heater for PCC88 of 7V. Another Philips data sheet shows 7.6V which is the one I have based the design on. Telefunken valves made by Siemens are quoted as 7V heater. I am bloody confused myself now. Thanks Alan but you say you use a Matsushita 7DJ8/PCC88 - That's exactly what I have here (and linked to previously at Watford Valves) yet you say it's not correct.... I am well confused.
I know, join the club. I was under the impression that the 'real' PCC88 heater voltage was 7.6V. Just had another look at the data sheets, The Philips data from 1957 shows 7V, the Philips data from 1970 shows 7.6V. The P rated heater is designed to work at a current of 300mA, originally in a chain of other P rated valves with 300mA heaters. In this configuration it doesn't really matter if the voltage across the heater is slightly different, but of course the valves in the BB are not being powered in series. |
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Jun 1, 2020 16:21:48 GMT
I use Tesla pcc88s no issues . You can order a pair fairly cheaply form eastern Europe on the bay. A stock build apart from Mundorf cap so pretty much to spec.
Yeah mine is to spec too. It may well be that there's some other issue on my build but until I'm sure my valves are ok I can't chase two issues. What is really odd is that the valves I have work in Alan's build so maybe that suggests some other issue anyway and "Valvegate" pointed us down the wrong path lol
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Jun 2, 2020 11:23:11 GMT
I know, join the club. I was under the impression that the 'real' PCC88 heater voltage was 7.6V. Just had another look at the data sheets, The Philips data from 1957 shows 7V, the Philips data from 1970 shows 7.6V. The P rated heater is designed to work at a current of 300mA, originally in a chain of other P rated valves with 300mA heaters. In this configuration it doesn't really matter if the voltage across the heater is slightly different, but of course the valves in the BB are not being powered in series. Thanks Alan, There is no doubt my valves have a 7v heater so given you're using them do you feel mine should work too? If the answer is yes then I guess that suggests I have a problem elsewhere. If the answer is no, then apart from the confusion that brings, I'm wondering if I should just go ahead and buy some other PCC88 variant? I do realise we have the voltage lowering option to try too. |
|
Bigman80
Grandmaster
The HiFi Bear/Audioaddicts/Bigbottle Owner
Posts: 16,399
Member is Online
|
Post by Bigman80 on Jun 5, 2020 17:48:33 GMT
I know, join the club. I was under the impression that the 'real' PCC88 heater voltage was 7.6V. Just had another look at the data sheets, The Philips data from 1957 shows 7V, the Philips data from 1970 shows 7.6V. The P rated heater is designed to work at a current of 300mA, originally in a chain of other P rated valves with 300mA heaters. In this configuration it doesn't really matter if the voltage across the heater is slightly different, but of course the valves in the BB are not being powered in series. Thanks Alan, There is no doubt my valves have a 7v heater so given you're using them do you feel mine should work too? If the answer is yes then I guess that suggests I have a problem elsewhere. If the answer is no, then apart from the confusion that brings, I'm wondering if I should just go ahead and buy some other PCC88 variant? I do realise we have the voltage lowering option to try too. We have a mod to lower the valve voltage Alan said he'll drop you a PM with the details |
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Jun 5, 2020 18:54:50 GMT
Thanks Oli and yep I’m speaking with him. i did order more valves but chances are I’ll be in the same boat  |
|
Bigman80
Grandmaster
The HiFi Bear/Audioaddicts/Bigbottle Owner
Posts: 16,399
Member is Online
|
Post by Bigman80 on Jun 5, 2020 20:08:04 GMT
Thanks Oli and yep I’m speaking with him. i did order more valves but chances are I’ll be in the same boat Never hurts to have spares. |
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Jun 21, 2020 16:33:20 GMT
Well it’s up and running in the office system. It’s in here as I’m still fiddling with the internal wiring so I need to finish that off with some shielded cable I’ve ordered and then once done it can go up to the house for an MC test..... If you recall I struggled getting it going with my valves and even after I made some changes to the 7805 output I still had no joy so Alan kindly said he’d take a look at it. He replaced the 7805 (now on its 4th one), made the output changes permanent and bingo we have life. While it was with him he also fitted the soft start/power off mod as well as the fet boards. I can’t thank him enough for his support but just wanted to give him a public thumbs up too!  |
|
|
|
Post by firebottle on Jun 21, 2020 16:42:09 GMT
Your welcome Martin.
|
|
|
|
Post by antonio on Jun 22, 2020 16:58:50 GMT
That's tidy, has Mrs Scotty been in with her duster?
|
|
|
|
Post by jimbo on Jun 22, 2020 17:38:02 GMT
Nice system scotty. I expect the PMC speakers kick a bit of ass?
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Jun 23, 2020 6:49:56 GMT
That's tidy, has Mrs Scotty been in with her duster? Ha that's usually the case to be fair but I had a bit of a kit move around on Sunday so down to me for once  |
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Jun 23, 2020 6:58:56 GMT
Nice system scotty. I expect the PMC speakers kick a bit of ass?
Yeah I suppose they do a bit. I've had them since 2006/7 as I bought them for an A/V system originally, I also have the centre speaker tucked away. In fact that screen was part of the setup too. To be honest I find them a bit bright these days but not sure if it's me or the speakers so I never have it that loud....
|
|
|
|
Post by jimbo on Jun 24, 2020 4:08:53 GMT
Nice system scotty. I expect the PMC speakers kick a bit of ass?
Yeah I suppose they do a bit. I've had them since 2006/7 as I bought them for an A/V system originally, I also have the centre speaker tucked away. In fact that screen was part of the setup too. To be honest I find them a bit bright these days but not sure if it's me or the speakers so I never have it that loud....
PMC are usually a bit bright and can be a tad aggressive? |
|
