Sockets for 4p1l
I've had my eye on these 4p1L's for some time now, and your endorsement has finally persuaded me to order some. I have 10 on the way. I want to build a SE preamp, then a simple as possible push-pull power amp with them. Can you recommend a good source for reasonably priced sockets for them?
Regards,
William.
I've had my eye on these 4p1L's for some time now, and your endorsement has finally persuaded me to order some. I have 10 on the way. I want to build a SE preamp, then a simple as possible push-pull power amp with them. Can you recommend a good source for reasonably priced sockets for them?
Regards,
William.
Hi William;
I myself am looking for source of sockets for them. However, there are plenty of Chinese sockets on epay, but I have bad experience with 9-pin sockets from there that had contacts made of soft metal, they are like disposable... I had 3 original Russian military sockets, used 2 of them. Don't know where to get more. Russian sockets for loctal tubes I see on epay now are shielded, 4P1L beauty would be invisible inside of them, and it would be hard to swap tubes. One option I consider is to remove sockets from shields and solder them on PCB.
I myself am looking for source of sockets for them. However, there are plenty of Chinese sockets on epay, but I have bad experience with 9-pin sockets from there that had contacts made of soft metal, they are like disposable... I had 3 original Russian military sockets, used 2 of them. Don't know where to get more. Russian sockets for loctal tubes I see on epay now are shielded, 4P1L beauty would be invisible inside of them, and it would be hard to swap tubes. One option I consider is to remove sockets from shields and solder them on PCB.
I tried now with 5W output transformers from Grundig stereo radio. Results are even worse: they can't pass 2.5W on frequencies below 60 Hz, start saturating... Edcor 25W 5K:8 Ohm are still winners, but they are huge, like 100W transformers I use in my Pyramids.
What other OT options do I have? XSE15-8-4.5K? Or GXSE15-8-5K? Did anybody try them?
What other OT options do I have? XSE15-8-4.5K? Or GXSE15-8-5K? Did anybody try them?
Ah, yes. According to plate curves indeed plate resistance is 1k5
Speaking of oddball tubes, tubes you have available may be oddball to me.
I have lots of 6J5P, curves in triode mode are there:
6N16B was made for military as a tiny replacement for 6N1P. It is not most linear tube, but for loaded on CCS cathode follower it is more than adequate.
If 6J5P is oddball for you, you may replace it by analogs, like Russian 6J4, or American 6AH6 or 6AC7, they are all the same.
Speaking of oddball tubes, tubes you have available may be oddball to me.
I have lots of 6J5P, curves in triode mode are there:
6N16B was made for military as a tiny replacement for 6N1P. It is not most linear tube, but for loaded on CCS cathode follower it is more than adequate.
If 6J5P is oddball for you, you may replace it by analogs, like Russian 6J4, or American 6AH6 or 6AC7, they are all the same.
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I am currently running a DC coupled CCS loaded 4P1L-4P1L SE amp in the workshop , both valves are triode connected with G2 and G3 connected to the anode . It was going to be a driver stage for 845 but I connected a 5K SE OPTX instead of an IT to see how what it sounded like , I had already done a PP 4P1L amp which I use in the office which I was impressed with . 4P1L in SE sounds rather nice , although I do find this valve to be microphonic . Running the fils around 4V (in series) seems to help . Slightly low on gain as a power amp but can go fairly loud with sensitive speakers .
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316A
Sorry, no I was wrong ont hat number. It wasn't a 1k5, it was a 1S5...
see here: http://www.mif.pg.gda.pl/homepages/frank/sheets/020/1/1S5.pdf
I think you could also use a 1B2 and 1DF91 (pulled from an old forum post) but god knows what they are.....
Fran
see here: http://www.mif.pg.gda.pl/homepages/frank/sheets/020/1/1S5.pdf
I think you could also use a 1B2 and 1DF91 (pulled from an old forum post) but god knows what they are.....
Fran
Sorry, I haven't been particularly clear!!! Bed beckons.....
I had a chinese headphone amp that used the 4P1L valve with a 1s5 as driver (for which you could substitute 1B2 or 1DF91 - neither of which are common). It was a thing called a little dot 2 (model long discontinued and only later versions called little dot MK2 or 2+ or 2++ will show up in searches.
The amp sounded nice, I gather the 1s5 and 4P1L were old Russian military valve designed to run from batteries - hence the 4V heaters - you could run the heaters for the 1s2 in series. It just had caps on the output for headphones.
Fran
I had a chinese headphone amp that used the 4P1L valve with a 1s5 as driver (for which you could substitute 1B2 or 1DF91 - neither of which are common). It was a thing called a little dot 2 (model long discontinued and only later versions called little dot MK2 or 2+ or 2++ will show up in searches.
The amp sounded nice, I gather the 1s5 and 4P1L were old Russian military valve designed to run from batteries - hence the 4V heaters - you could run the heaters for the 1s2 in series. It just had caps on the output for headphones.
Fran
1s5 is a tiny high-mu tube with low transconductance.
It may be very good for hearphones, but for power amp I wanted to get everything 4P1L can offer, that's why used cathode follower to drive it.
Speaking of fancy tubes, I am going to use 12J1L and 12P17L tubes in the next version of high-end tiny power amp. 12P1L is very similar by characteristics to 4P1L.
It may be very good for hearphones, but for power amp I wanted to get everything 4P1L can offer, that's why used cathode follower to drive it.
Speaking of fancy tubes, I am going to use 12J1L and 12P17L tubes in the next version of high-end tiny power amp. 12P1L is very similar by characteristics to 4P1L.
I made output transformers for it using Edcor XCPP60-MS-4K -- reassembled laminates with an air gap about 0.2 mm using Capton film. No load inductance is about 18 Henry. Sounds gorgeous!
An externally hosted image should be here but it was not working when we last tested it.
Does it matter? It is work in progress.
I am going to try to replace 6N16B in cathode follower by 6J5P and if I like it, drill couple more holes for tube sockets. After breadbourding is finished I will mount everything carefully, order front panel, and make usual wooden cheeks wrapped in black vinyl, like on this picture:
VT50 (HL32K) DHT input stage with DN2540 CCS fed DC fils running 16R cathode resistor with filament bias with 100k anode load , 6N6 paralled concertina phase splitter with 10k loads top and bottom and LM1084 (CCS connected) DC fils on 4P1L . EZ81 rectifier 1uF 8H 60R choke into 220uF cap per channel . The component values of the cathode bias network I'm unable to remember but I do remember using 91R resistors to strap G2 and G3 to the anode and 196R grid stoppers with 150K grid resistors for the 4P1L . Around 3 watts per channel
The amp is quite microphonic , not really suitable for high efficiency speakers
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