Static noise with PV-14L

[admin]

I acquired a PV-14L (along with an MV-55) for a 2nd mini system and hooked it up today.

I think there is an issue with the PV-14L. There is a considerable static noise present that lightly can wax and wane but is always present at considerable volume. It's not a ground loop hum and doesn't seem altered by the volume control. I'm sure it's the PV-14L as I tried an alternative source for the MV-55 and it was then dead quiet. I tried different inputs on the PV-14L and same issue. When I press the Mute button the PV-14L, the static goes away.

Internal visual inspection seems fine but I did post a picture if somebody can see some obvious issue. Any input would be appreciated.

[admin]

I tried swapping the two tubes with each other as that was a trick I had used to identify a bad tube in my PV-12L back in the day. Unfortunately, it did not change the outcome. The static may be a little louder in one channel than the other and now I'm wondering if that amplitude difference switched channels with the tube change, but that may be my imagination?

[AnotherJohnson]

I’d bet that both tubes are noisy. This is an old unit, priced “right.”

If it’s not the tubes, then cleaning pots is next.

Noisy resistor can also bring this sort of hash, but it’s probably a pot or tubes.

[admin]

I was also thinking of starting with a new set of tubes. Obviously not the best time to buy tubes but such is life.

[AnotherJohnson]

I was also thinking of starting with a new set of tubes. Obviously not the best time to buy tubes but such is life.

I’d send you two to try, but that’s not a common tube, and I do not have them in my stores.

[admin]

Thanks AJ. I started the search. One of my tube suppliers that I used in the past didn't have any in stock. "Thetubestore.com" has some listed so I sent them an email on suggestions to what they would recommend. They are $20 a piece so not too bad overall. Thank god it's just some small input tubes and not the bigger stuff on the MV-55!

[AnotherJohnson]

https://www.thetubestore.com/preamp-tub ... tube-types

I was just about to send you this link.

I paid CJ $120 a piece for 3 6922 equivalents last year “just to be a good sport.”

[admin]

I was looking at that one but there was no brand. This is the other one I was looking at:

https://www.thetubestore.com/product/1664?quantity=1

I didn't know what the difference was between the two or which one they would recommend.

[admin]

Jon from thetubestore.com got back to me. I put in the order for the two new tubes. Hopefully they will arrive quickly so I can continue with the troubleshooting.

[AnotherJohnson]

I made a big order from them on Sunday. They shipped via ups on Monday and are on track to arrive tomorrow.

I don’t know how good their tubes are … I’ve bought from them before and don’t remember being unhappy. I wanted to fill out my inventory. I like to keep enough tubes to retube everything completely at one time.

Two matched sextets and four matched pairs of KT150s ( I had two matched octets).

A dozen 6H30s (I had 9)

Two matched pairs of 6550s (I had 1)

Maybe some other stuff.

I’ve got a lot of new 6922 equivalents that I don’t need. I sold the extra KT120s. I’d sell them at fair prices.

When ARC or Upscale are selling again, I’ll probably make one more big order from one of them, and I should be set without supply chain nightmares.

I suppose this could be argued as tube hoarding, but I’ve always kept at least one tube change on hand. I’m not buying beyond my historic pattern.

[AnotherJohnson]

The other thing to keep in mind is that the PV14L is not going to go head to head with an ET7s2. If the ET7s2 is your reference, none of the 20 year old CJ or ARC offerings are going to please you unless you’re really going for a vintage sound. A bit of hash may be one of the difficult to resolve differences. Kevin Deal would suggest that you listen around the tube noise. You may be afflicted with better hearing than an old hippie.

[admin]

Your are correct, and the intention was never to compete with the likes of the ET7s2 nor the ART amps. I wanted a small system downstairs in our sun room but with some major stipulations. First, the room was not going to be turned into a "listening room." It's a living space so the stereo should be rather inconspicuous. So, preamp, amp, bookshelf speakers, and a small digital source. That's it. Also, the budget for this 2nd system is to be under $2k. So expectations are going to be appropriate. Currently I have some RCA ceiling speakers (that came with the house) running off a Kenwood stereo receiver for ambient background music downstairs. I wanted a step up from that meager arrangement.

As for the status of the tubes. I made the order today and Jon from thetubestore.com says it will ship out today. Quick service.

[AnotherJohnson]

I’m sure it will be fun to have. And if you get the PV14L sorted out, you’re in a great position to sell it later without loss, even if it takes a bit of work.

It’s great that the MV55 is behaving well. Even if you retubed it, you’d still be in a good position on that too.

Back to the tubes … ARC is running a matched sextet of KT150s for output in each REF250SE, but the kicker is that they’re running a matched pair of KT150s as the driver tubes too. I’d not seen that before. My ARC power supplies are all using the 6550WE and 6H30. Both the REF 6SE and the REF Phono 3 are based on six 6H30s.

[admin]

I just hope the problem are the tubes and not something more complicated.

As for running KT150's on both ends, that is something I have never seen. I wonder why,.. but I'm sure there is a reason as they wouldn't go that way unless they felt it improved the sound.

[AnotherJohnson]

Even if you had to send it to CJ and pay $800, you’d still be ahead when you go to sell.

But I don’t think it will need to go back. I’m glad you were able to find the tubes at a fair price.

[roberto]

Hola Admin,

The orange color of the Caps on the bottom left seems to be non original. If these caps are part of the signal, these could be the culprit of the problem.

Reading you also, the most principal suspect are the small signal tubes. You should not use the EPL circuit. It is too noisy. If you want to use the preamp for HT purpose, use the AUX input bring the volume knob to about 70% and use the HT device to control the needed volume.

Happy listening!

[admin]

Roberto,
Thanks for the input. Those caps did look a little out of place, but they don't appear to be bulging or any obvious defect. Nor did I see any signs of re-soldering. Unfortunately, I can find any pictures online of the PV-14L's of others to compare.

I'm not planning to use it for home theater purposes. Just a small 2nd system to listen to music downstairs when I'm reading or hanging out.

I ordered the tubes yesterday afternoon, and UPS says they are going to be delivering today. If so, that's amazingly fast,... especially considering that thetubestore.com is in Canada I believe. With a little luck, I should have more news later today.

EDIT: Quick post update. I tried a different image search engine and it looks like those caps are original. https://www.usaudiomart.com/details/649 ... s/1482158/

[admin]

Ok, tubes arrived. Looks like it was a tube issue after all. Thank god.

I put the new tubes in and the fairly loud waxing and waning static is gone. I will say there is still a very faint baseline static that is only audible when I get closer than 3 feet to the speaker and there is no music playing. Again, the mute button the PV-14L will completely silence this. The speakers I am using are some Martin Logan 35XTi's which are pretty sensitive at 92db, so it could be that. I am also using a Wiim Mini as a streamer source via 3.5mm jack to RCA connectors, so perhaps that is not the best output method either. Also was using super cheap cables on the test bench. I'm not sure how much effort I am going to put into hunting that down as it will not be audible from listening position, especially when actually playing music.

Overall, I think this is a great success and I'm happy. Small hiccup that was luckily solved quickly. I only had a little time to "play" with the setup today but I will try to get this in it's final position in the next week or so. I'll post about what I feel the overall sound is like.

Also, I have to give a shoutout here to our user rscuria, who has been an absolute gentleman during this transaction.

Furthermore, I have to also acknowledge thetubestore.com. I emailed Jon there yesterday around noon, had an email response in an hour or two, made the tube purchase yesterday afternoon, and I got the tubes today. I can't believe I got these overnight from Canada (using standard UPS shipping). Pricing was very fair (especially in today's world) at $20 per 6C4.

[roberto]

Thanks for letting me know that are factory caps. Sprague are a very well known brand making caps.

Being the speakers so sensitive, just play any song and adjust your pleasant level. Then stop the music. Don't touch anything else and leave the volume knob untouched. If you don't have any noise, you are OK.

I wish you a very happy listening!