- Posted by agreenspan (A) on May 20, 2013 at 14:08:25
Hi everyone. I just finished my very first amplifier kit build the other day; the Audio Note Kit 1. It has been a fun and educational experience. The sound I am getting so far is the best that I have ever had with my speakers (Zu Soul Superfly). I got custom output transformers with my kit, since my speakers are 16 ohm (8 and 16 ohm taps.)
I just had a couple of questions, and was looking for advice:
1. What tubes do you recommend for this amp?
The stock tubes sound nice, but I was wondering what upgrades everyone recommended. The kit came with:
Electro Harmonix 6SN7 and 5U4GB, Phillips NOS 5687, and Shuguang 300B (the regular ones).
I am told that the Phillips 5687's that I already have are VERY nice, though Tungsol is also recommended. Also, both the Shuguang Treasure and Emission Labs 300B have been recommended.
What do you guys think?
2. My second question involves the 5U4GB tube: I think that I may have wired something wrong, or made some other mistake (cold joint somewhere?) I purchased two NOS 5U4GB tubes (Raytheon and Sylvania) to try. Both of them arc when I first turn on the amp with quite a little lightning show for about one or two seconds, and then settle down and don't arc anymore.
The Electro Harmonix (new) that came with the kit does NOT arc, but it makes a constant "sizzling / rattling" noise; physically at the tube (not through the speakers). At turn on, the E.H. tube makes a few "boing boing" springy noises, and then does the sizzling sound from then on.
The NOS tubes are physically silent after the initial fireworks display.
However, as far as noise through one of the SPEAKERS, intermittently, with the E.H. tube, a "crackling / static" noise was coming out of the left speaker after startup, though I had to listen closely and could not hear it with music playing.
With the Raytheon, the sound is different (also intermittent). There is a light "tap tap thump thump" noise that progressively gets faster.
The Sylvania, so far, has no noise.
Turning the amp off, waiting and turning it on again will sometimes get rid of the noise coming out of the left SPEAKER.
Just for fun, I tried switching the two 300B positions, and both noises then moved to the RIGHT speaker.
I wonder if this is just a coincidence, and one of the 300B's is acting funny, although the noise coming from the speaker varies depending on the rectifier tube that is in.
Anyway, sorry to bore you all. ANY help or suggestions you could give would be appreciated.
Thanks.
Follow Ups:
- RE: Brand New Kit 1 - Questions - IkeH 14:37:53 05/21/13
(1)
- In Reply to: RE: Brand New Kit 1 - Questions posted by agreenspan on May 20, 2013 at 14:08:25
Congratulations on your first kit amp!
As to the arc of the rectifier tubes, I have tried at least 10 different make/types of rectifier tubes (most NOS) for my Kit 1 and learned that many rectifier tubes do arc. It was bit unnerving at first but after speaking with many veterans of the tube electronics/trade and confirmed that it is what some rectifier tubes do. I have been using a Mullard Australia NOS 5AS4 for the past 4 years or so and it arcs every time I turn on the Kit 1 but without any issues. Not sure about noise from EH 5AU4GB but I suspect that your tube could be defective.
For the other noise issues, I tend to agree astrostar59, it could be a loose connection, cold joint etc. .
As to the tube recommendations, I have written about my experience with Kit 1 on my own website especially on choosing tubes so please take a look (link below).
Happy listening☺
Ike
- RE: Brand New Kit 1 - Questions - agreenspan 19:49:48 05/22/13
(0)
- In Reply to: RE: Brand New Kit 1 - Questions posted by IkeH on May 21, 2013 at 14:37:53
Hi IkeH
Thanks for the advice. Thats encouraging. Its kind of confusing for me though, because I'm new at all this, and I've asked several experts. I've been told everything from: 'The PSU of the kit 1 is similar to the Audio Note Meishu, and it is a known quirk that they cause rectifier tubes to arc so don't worry'....... all the way to...... 'Oh no! Shut it off and don't turn it on again until you fix it, 'lest you cause a nuclear explosion' ;-)
I really enjoyed your website too! I learned a bunch.
Thanks.
- RE: Brand New Kit 1 - Questions - agreenspan 19:49:48 05/22/13
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- RE: Brand New Kit 1 - Questions - astrostar59 04:34:32 05/21/13
(1)
- In Reply to: RE: Brand New Kit 1 - Questions posted by agreenspan on May 20, 2013 at 14:08:25
I would recommend you talk to Brian re tube issues. He will be able to give you good advice on what to do. It could be a dry solder joint, or dirty tube pins. MAKE SURE you do not use your volt meter on a live amp! Strong voltages in tube amps can kill. Best thing would be to power down, and half an hour later, take off the top and check connections, then check resistance across connections, to ensure you solder joints are sound. Look for dull joints or solder blobs very close to each other. There could be a bad joint or a short.
If all seems ok, check your resistors for correct readings on the ohm scale. And of course, check they in the right locations, as if wrong it can bump up the voltages out of specs.
Moving valve to the other channel will help to narrow your search. If the issue moves with the same valve, it is the valve, not the amp.
On tubes, I use Tungsol 5687 1960s NOS D Getters. They are the best sounding I have found and are not crazy money. I get 2 years use out of them (switched on all the time in my Audio Note Pre-amp).
For 300b I love the Pure Music TJ Solid Mesh 300b. They sound very dynamic and have great bass, plus keep all the best attributes of the classic 300b sound in my Audio Note Mono Blocks.
- RE: Brand New Kit 1 - Questions - agreenspan 19:40:28 05/22/13
(0)
- In Reply to: RE: Brand New Kit 1 - Questions posted by astrostar59 on May 21, 2013 at 04:34:32
Hi Astrostar,
Thanks for your tube recommendations. I will learn more about them. Brian has been helping me along, I'm just looking for as much knowledge and advice as I can find.
I put in two different 300B tubes today, and the weird noises coming through the speakers are now GONE.
I figured it must be one of the 300B tubes, because when I switched their positions, the noise moved to the opposite channel. I'm glad that issue is fixed.
As far as the rectifiers: I've learned that originally, the Kit 1 was specified with a 100uF capacitor in the PSU after the choke, but it was changed to 220uF to reduce hum.
Do you think changing that capacitor would help?
Thanks.
- RE: Brand New Kit 1 - Questions - agreenspan 19:40:28 05/22/13
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