[Mullet]

Hrrrm. I decided to pop in my Mullard 4010s... not an issue with hum. Quiet like the Chinese tubes. The eBay seller I bought the Tung Sols from is kindly sending me a new tube -- hopefully a pair

Just for craps and giggles I decided to also pop in my RCA tubes. They had a barely noticeable hum when popped in -- nothing like the Tung Sols though. I have several hypothesis here. First, is that that the pins are dirty. They need to be cleaned. Second, that possibly the amp only likes certain tubes. Third, that the tube in my case was defective. I'm going to go with #3. I swapped it back and forth between left and right channels and I the hum followed the swap. I really don't want this to be a tube / amp synergy issue.

~Mullet

 

[Godkin]

The 336i and 332 were sensitive when it came to tubes: some would work well, others were a nightmare. I remember with my 332, the SYLVANIA 5654 Greens hummed like hell, as did the VOSHKOD 6J1P-EVs. The MULLARD EF95/M8100/CV4010s were fine, as were the RCAs, TUNG-SOLs, RAYTHEONs and WEs.

The DV 3322 is most definately an impovement: doesn't matter what you put into it, it remains totally silent.

 

[yuking09]

Quote:

Originally Posted by BigTony /img/forum/go_quote.gif Well after 2 weeks and lots of burn in a few lasting thoughts: On the downside: Way too much gain, even with -10db attenuators its LOUD ... Going to borrow/buy a sound meter to record the levels, but in comparison with my other amps, min. on the 332S is about 75% max. on my Jade. Hum ... this started out quite noisey, and has dropped off quite alot, but its ever present, and if you turn off the power the hum dissapears before the music does - so its looking like is a circuit design and not a tube/burn in issue. The hum isn't noticable when music is playing, and to give a fair comparison - listening to an orchestra you can often hear (with cans) various rustling, coughing, scraping of chairs etc - well the hum level is at that level, you can hear it, but its not in your face. Can I live with it ... well.... And the upside: Sound :- well it just sound gorgeous, really full rich tone with the HD-650's. You can hear that wonderful full base, tight, resonant, full of life; and the mids and highs are clear and crisp. All the microdetails are present, lots of hidden sounds etc just pop out unexpected at you; the soundstage is just that little bit fuller than the Jade for example, there is more room around instruments, everything is just that little bit more in focus. You can follow an instrument easily, it never gets congested. I've switched back and forth with the 332S and the Jade and it just has that little something extra. In balance - do the pros outweigh the cons? Very tricky .. The black background of the Jade is great, it allows you to forget about the amp/headphones and just enjoy the music, that little hum on the 332S just stops you short of forgetting the gear.. maybe its because my mind is trying to trick me; is the hum gone? ah no.. there it is!

We are working to change the Potentiometer.Because Chinese New Year ,Express companies do not work. When Chinese New Year is over,I'll give your issued with a new potentiometer.

 

[BigTony]

Doh- i had the -10db atenuators in there.
Volume pots at 7:30(ish) 72db with the attenuators, 85db without.

 

[Audict123]

Quote:

Originally Posted by yuking09 /img/forum/go_quote.gif We are working to change the Potentiometer.Because Chinese New Year ,Express companies do not work. When Chinese New Year is over,I'll give your issued with a new potentiometer.

It's a good thing you are addressing this Yuking09.

 

[Audict123]

My 332s is still not hum free after about 100 hours of break in. I'm about to try the 'Fitz mod' http://www.head-fi.org/forums/2321506-post11.html that was quite popular on the 336 to tackle hum. It's simply a capacitor that bypasses the cathode resistor. In the 336, some used 100uF, some 220uF (all 50V) and it seemingly worked very well. The question of course is: what value to use? In the 332S, a different tube is used; the cathode resistor is *CORRECTED VALUE (after looking at the right resistor

) ->* 1 kohm. Anyone knows the resistor value in the 336? A clear picture that shows the color coding on the resistor should also do to determine that value. Yuking or anyone else: do you know that resistor value? Even better: do you have a suggestion what (cathode resistor bypass) capacitor value to use in the 332S? I guess if that resistor value is the same, I should use the same capacitor value too. In selecting the value, a so-called bypass capacitor nomogram can be used (see picture). If no one knows, I'll start of with the 100 uF value.

I had some hum with the stock russian tubes and the 403B's and although perhaps a tube like the M8100 could be hum free I want a universal solution.

 

[Audict123]

Quote:

Originally Posted by arie123 /img/forum/go_quote.gif Anyone knows the resistor value in the 336? A clear picture that shows the color coding on the resistor should also do to determine that value. Yuking or anyone else: do you know that resistor value? Even better: do you have a suggestion what (cathode resistor bypass) capacitor value to use in the 332S? I guess if that resistor value is the same, I should use the same capacitor value too. In selecting the value, a so-called bypass capacitor nomogram can be used (see picture). If no one knows, I'll start of with the 100 uF value.

*CORRECTED POST; THE CATHODE BYPASS RESISTOR VALUE IN THE 332S IS 1 KOHM* Just found some pics on the bottom of http://www.head-fi.org/forums/f5/dv-...79/index2.html by Aryntha that show it's also 1K in the 336.

That's easy than, no nomogram needed at all. I'll just use one of the two 100uF or 220uF values that people used as bypass caps in the 336.

 

[deltaspirit]

Well, I have a feeling my 332S has bitten the dust. I was watching some youtube when all of a sudden the left channel starts buzzing VERY loudly and then cracks I quickly unplugged my headphones because I thought it was going to blow the driver. I hooked the amp up with a different source and everything is fine for a couple of seconds then wham same crap. Could it be the tubes? I really don't want to send this thing back to china.

 

[Mullet]

What you just had sounds exactly what I had happen to my 332c a few days ago. I decided to take out the stock tubes and put in Ulys and some NOS Tung Sol 6AK5s. As soon as I plugged in the Tung Sols I could hear this super loud buzz out of my right channel. I thought maybe these puppies need burn in. Then BANG... POP! I hear this super loud pop noise and I turned the amp off. Next I swapped the tubes back and forth between left and right channel and the super buzz followed. I popped in some NOS RCA 6AK5Ws and everything has been fine since then. The eBay seller who sold me the matched NOS Tung Sols is sending me a new pair of tubes.

Hope your outcome is the same as mine.

 

[deltaspirit]

Quote:

Originally Posted by Mullet /img/forum/go_quote.gif What you just had sounds exactly what I had happen to my 332c a few days ago. I decided to take out the stock tubes and put in Ulys and some NOS Tung Sol 6AK5s. As soon as I plugged in the Tung Sols I could hear this super loud buzz out of my right channel. I thought maybe these puppies need burn in. Then BANG... POP! I hear this super loud pop noise and I turned the amp off. Next I swapped the tubes back and forth between left and right channel and the super buzz followed. I popped in some NOS RCA 6AK5Ws and everything has been fine since then. The eBay seller who sold me the matched NOS Tung Sols is sending me a new pair of tubes. Hope your outcome is the same as mine.

Phew, good to know. Guess I'm going to have to get myself some decent tubes. I have not stayed up to date with this thread very much. What are some recommended tubes?

 

[Mullet]

Quote:

Originally Posted by deltaspirit /img/forum/go_quote.gif Phew, good to know. Guess I'm going to have to get myself some decent tubes. I have not stayed up to date with this thread very much. What are some recommended tubes?

Currently I have the Ulyanovs paired up with NOS RCA 6AK5Ws from 1963. No complaints thus far. There's plenty of mid end, the lows are deep and full. The highs are there and not overbearing. This is all with my Alessandro MS2s. Who said you couldn't use low impedance phones with this amp? They sound pretty damn good to me. A few weeks back and I would have told you different when I still had the stock tubes plugged in.

The highest regarded tubes to get for this amp are *apparently* the Ericsson 403Bs (hard to come by) and the Western Electric 403Bs. Others that are popular are the Mullard CV4010s, RCA 6AK5s, Tung Sol 6AK5s, and the list goes on. Of course, you're going to want to have both the Svetlana and Ulyanov 6S19Ps to switch out.

I haven't done a lot of tube rolling yet because I'm trying to give the RCA/Uly combo a good try and then I'll move on to Tung Sols and eventually to the Ericssons. I have several different pairs waiting in a box -- waiting for their turn to bask in the light.

 

[ogygia]

Is there anyone can recable the signal input connection of 332s? Trying to make it not crossing over the power wire and stick to the case. I think it is the best solution, since someone proved my power off test already...The noise may come from power.

Adding capacitor will have unknown effect on sound....Why don't focus on the original power/signal design problem?

 

[Audict123]

Quote:

Originally Posted by deltaspirit /img/forum/go_quote.gif Well, I have a feeling my 332S has bitten the dust. I was watching some youtube when all of a sudden the left channel starts buzzing VERY loudly and then cracks I quickly unplugged my headphones because I thought it was going to blow the driver. I hooked the amp up with a different source and everything is fine for a couple of seconds then wham same crap. Could it be the tubes? I really don't want to send this thing back to china.

Were these still the stock tubes?

 

[BigTony]

Quote:

Originally Posted by ogygia /img/forum/go_quote.gif Is there anyone can recable the signal input connection of 332s? Trying to make it not crossing over the power wire and stick to the case. I think it is the best solution, since someone proved my power off test already...The noise may come from power. Adding capacitor will have unknown effect on sound....Why don't focus on the original power/signal design problem?

I've not opened up the amp, maybe this Sunday. Not sure about recabling. The hum on my amp is only from the LHS, so I'll look at that section. I'll take some picture too while I'm in there.

 

[BigTony]

Quote:

Originally Posted by deltaspirit /img/forum/go_quote.gif Phew, good to know. Guess I'm going to have to get myself some decent tubes. I have not stayed up to date with this thread very much. What are some recommended tubes?

I really like the Mullard 8100 (CV4010) tubes, lots of nice rich tone.