One more 4P1L SE - Page 3

Wavebourn · 23rd February 2011, 02:13 AM

Tried 10W transformers Utah 7390. Total merde... Bass is Ok down to 40 Hz on full power, below it starts saturating. But -3 dB is on 5 KHz already... I have a pair from Grundig stereo radio, will try them.

hihopes · 23rd February 2011, 08:33 PM

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.

Wavebourn · 23rd February 2011, 10:29 PM

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.

Wavebourn · 23rd February 2011, 11:03 PM

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?

quikie22 · 23rd February 2011, 11:33 PM

just ordered some Chinese sockets on epay..... will let you guys know the quality. the sockets seem to cost more than the tubes.

hihopes · 06:56 PM

That seems to be the way it works. I had hoped somebody had found an economical source for them. Did you order the ones that are $9.99 for 4 with free shipping?

woodturner-fran · 24th February 2011, 06:51 PM

The little dot amp use oddball driver tubes.... 1k5 I think......

Wavebourn · 24th February 2011, 07:22 PM

Quote:

Originally Posted by woodturner-fran

The little dot amp use oddball driver tubes.... 1k5 I think......

What is 1k5?

hihopes · 24th February 2011, 07:34 PM

1k5 = directly heated pentode by the look of it.

Wavebourn · 08:21 PM

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.

23rd February 2011, 02:13 AM	#21
Wavebourn diyAudio Member Join Date: Sep 2006 Location: Pleasant Hill, CA	Tried 10W transformers Utah 7390. Total merde... Bass is Ok down to 40 Hz on full power, below it starts saturating. But -3 dB is on 5 KHz already... I have a pair from Grundig stereo radio, will try them. __________________ If I disappear suddenly, that means I finally created a time machine and pushed wrong button that brought me to Stalin's Russia. In any experiment any result is the result. Even if it is negative.

23rd February 2011, 08:33 PM	#22
hihopes diyAudio Member Join Date: Sep 2004 Location: Cape Town	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.

23rd February 2011, 10:29 PM	#23
Wavebourn diyAudio Member Join Date: Sep 2006 Location: Pleasant Hill, CA	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. __________________ If I disappear suddenly, that means I finally created a time machine and pushed wrong button that brought me to Stalin's Russia. In any experiment any result is the result. Even if it is negative.

23rd February 2011, 11:03 PM	#24
Wavebourn diyAudio Member Join Date: Sep 2006 Location: Pleasant Hill, CA	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? __________________ If I disappear suddenly, that means I finally created a time machine and pushed wrong button that brought me to Stalin's Russia. In any experiment any result is the result. Even if it is negative.

24th February 2011, 06:47 PM	#26
hihopes diyAudio Member Join Date: Sep 2004 Location: Cape Town	That seems to be the way it works. I had hoped somebody had found an economical source for them. Did you order the ones that are $9.99 for 4 with free shipping? Last edited by hihopes; 24th February 2011 at 06:56 PM. Reason: new info


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23rd February 2011, 11:33 PM	#25
quikie22 diyAudio Member Join Date: Sep 2009	just ordered some Chinese sockets on epay..... will let you guys know the quality. the sockets seem to cost more than the tubes.

24th February 2011, 06:51 PM	#27
woodturner-fran diyAudio Member Join Date: Jan 2006 Location: Ireland	The little dot amp use oddball driver tubes.... 1k5 I think......

24th February 2011, 07:34 PM	#29
hihopes diyAudio Member Join Date: Sep 2004 Location: Cape Town	1k5 = directly heated pentode by the look of it.

24th February 2011, 07:54 PM	#30
Wavebourn diyAudio Member Join Date: Sep 2006 Location: Pleasant Hill, CA	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. __________________ If I disappear suddenly, that means I finally created a time machine and pushed wrong button that brought me to Stalin's Russia. In any experiment any result is the result. Even if it is negative. Last edited by Wavebourn; 24th February 2011 at 08:21 PM.

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