[snejk]

So, I got the Groove Tubes GT-5751M for my HD Super a couple of days ago and after letting the amp warm up for a while I started listening. I really liked the presentation of the GT, more lively than my previous Sylvania, but I also noticed a crackling noise in the right channel. It is barely audible when playing music, but in silent passages I can hear it and the noise is also there when no source is connected. The noise isn't responding to adjusting the volume either.

The noise is like radio static, or like the static you get when playing dusty vinyl. The noise is there for 5-10 seconds, goes away for a few seconds and then comes back.

I switched back to my Sylvania gold pin and at first I didn't notice the noise but after a while I realised it was there with this tube as well, but more faint. I don't know if I just haven't noticed it previously or if the noise appeared when switching to the new 5751.

After this I switched the 12B4A pair, and the noise was now in the left channel. So I guess it's safe to assume that the problem lies with the 12B4A's? I'll have to get a new pair to try out on the amp.

As I am a tube noob, does anyone have any insight into this kind of problem? Is it possible that the new 5751 tube could have "hurt" the 12B4A tube? Is there any way to fix the tube without buying new? I have tried re-inserting them a couple of times.

Thankful for any comments!

 

[mrarroyo]

The 5751 is a 12AX7 with a lower gain (about 70%). It is interchangeably w/ it as well as the 7025. No worries.

 

[SemiAudiophile]

Quote:

Originally Posted by snejk /img/forum/go_quote.gif So, I got the Groove Tubes GT-5751M for my HD Super a couple of days ago and after letting the amp warm up for a while I started listening. I really liked the presentation of the GT, more lively than my previous Sylvania, but I also noticed a crackling noise in the right channel. It is barely audible when playing music, but in silent passages I can hear it and the noise is also there when no source is connected. The noise isn't responding to adjusting the volume either. The noise is like radio static, or like the static you get when playing dusty vinyl. The noise is there for 5-10 seconds, goes away for a few seconds and then comes back. I switched back to my Sylvania gold pin and at first I didn't notice the noise but after a while I realised it was there with this tube as well, but more faint. I don't know if I just haven't noticed it previously or if the noise appeared when switching to the new 5751. After this I switched the 12B4A pair, and the noise was now in the left channel. So I guess it's safe to assume that the problem lies with the 12B4A's? I'll have to get a new pair to try out on the amp. As I am a tube noob, does anyone have any insight into this kind of problem? Is it possible that the new 5751 tube could have "hurt" the 12B4A tube? Is there any way to fix the tube without buying new? I have tried re-inserting them a couple of times. Thankful for any comments!

could be dirty pins or just a bad tube. i've had similar experiences before. actually one of the Sylvania's i picked up had the same problem. faint static/crackling in one channel. try cleaning the pins with Deoxit.

 

[indydieselnut]

I was wondering if the other people on the build list for the 250 special edition amp would be on head-fi. I should receive s/n 3 sometime later this month. It feels good to get off the merry-go-round for a while and just get to know one amp. Since there are only 3-4 of these ordered/delivered at this point it's silly to start another thread. Once I have some time with the amp I'll post my impressions. I have some Genelex (new production) EL84 and EH gold-pin 12AX7's for the amp. I'm sticking with new production until I get a baseline impression of the sound. It's good to join the MAD family!

 

[snejk]

Quote:

Originally Posted by SemiAudiophile /img/forum/go_quote.gif could be dirty pins or just a bad tube. i've had similar experiences before. actually one of the Sylvania's i picked up had the same problem. faint static/crackling in one channel. try cleaning the pins with Deoxit.

Will get some Deoxit and try it out, and I just ordered a pair of Sylvania 12B4A as well, don't want to miss any more listening time on my MAD

Another thing I have noticed is that the gain seems to be higher on the GT 5751 than on the Sylvania 5751. Is this normal? I thought all 5751 had the same specs?

 

[snejk]

Quote:

Originally Posted by indydieselnut /img/forum/go_quote.gif I was wondering if the other people on the build list for the 250 special edition amp would be on head-fi. I should receive s/n 3 sometime later this month. It feels good to get off the merry-go-round for a while and just get to know one amp. Since there are only 3-4 of these ordered/delivered at this point it's silly to start another thread. Once I have some time with the amp I'll post my impressions. I have some Genelex (new production) EL84 and EH gold-pin 12AX7's for the amp. I'm sticking with new production until I get a baseline impression of the sound. It's good to join the MAD family!

There's already a thread started for the 250:

http://www.head-fi.org/forums/f5/map...50-amp-444941/

I am a bit proud as my HD Super made Struts order a HD250

 

[raulcf77]

Hi guys, I´m from Spain...I have the RS1i from grado, and I´m thinking to get the mapletree ear+hd or woo6 upgraded with the sophia...¿what do you think about? Thanks in advance

 

[MacedonianHero]

Quote:

Originally Posted by raulcf77 /img/forum/go_quote.gif Hi guys, I´m from Spain...I have the RS1i from grado, and I´m thinking to get the mapletree ear+hd or woo6 upgraded with the sophia...¿what do you think about? Thanks in advance

I own a Mapletree Ear+HD and couldn't be happier! My buddy owns a Woo6 and I like it too very much, just not as much as my Mapletree!

 

[raulcf77]

Quote:

Originally Posted by MacedonianHero /img/forum/go_quote.gif I own a Mapletree Ear+HD and couldn't be happier! My buddy owns a Woo6 and I like it too very much, just not as much as my Mapletree!

Thank you for your answer! I have to buy a head amp to improve my equipment (RS1 + Marantz SA7001), and I have definitely 2 options: mapletree ear+hd or woo6 with the sophia rectifier....The woo6 looks better in appeareance (more lligths when the tube glows!

i think!), but all the people that i have read are very happy with the mapletree!
Thank you and sorry for my english

 

[Gradofan2]

Quote:

Originally Posted by SemiAudiophile /img/forum/go_quote.gif could be dirty pins or just a bad tube. i've had similar experiences before. actually one of the Sylvania's i picked up had the same problem. faint static/crackling in one channel. try cleaning the pins with Deoxit.

I had a few tubes that sounded similar with my DV332. I cleaned the pins with WD40 and an old toothbrush... and... spread the pins a bit to fit more tightly in the sockets - solved the problem.

Be careful spreading the pins to avoid breaking the glass. I support the base by gently pressing the opposite direction (in) with one finger tip, as I gently press the tip of the pin in the other direction (out) - gently.

 

[BigAmish]

Quote:

Originally Posted by raulcf77 /img/forum/go_quote.gif Hi guys, I´m from Spain...I have the RS1i from grado, and I´m thinking to get the mapletree ear+hd or woo6 upgraded with the sophia...¿what do you think about? Thanks in advance

I have the RS-1 -> MAD Ear+ pairing you are asking about & couldn't be happier. Stunningly wonderful sound, & tube rolling to your own specific tastes is fun & doesn't *have* to be all that expansive to do. I have heard several tube amps with my RS-1s at various meets & although they all sounded great in different ways, the MAD Ear+/RS-1 pairing seems to be something special. Having said that though, I have never listened to the Woo6...which I hear can be pretty capable as well.

 

[SemiAudiophile]

i had the Woo 6 SE prior to owning the MAD. i don't know if it was my setup, but i didn't like how it sounded very much with the RS1i. the sound was way too forward and in my face. if you read reviews of the Woo 6, that's generally the characteristic of that amp, which may be something you either like or don't like. personal preference. the Woo 6 SE is slightly more refined (cost more too), but i am happier with my MAD.

 

[raulcf77]

Quote:

Originally Posted by SemiAudiophile /img/forum/go_quote.gif i had the Woo 6 SE prior to owning the MAD. i don't know if it was my setup, but i didn't like how it sounded very much with the RS1i. the sound was way too forward and in my face. if you read reviews of the Woo 6, that's generally the characteristic of that amp, which may be something you either like or don't like. personal preference. the Woo 6 SE is slightly more refined (cost more too), but i am happier with my MAD.

Ok, thank you very much for your aclaration, it´s very useful for me! I think I´m going to buy the mapletree definitely...I only prefer the woo6 for its appearance, I think it looks better than mapletree (especially when the tube glows), but definitely I´m going to buy the mapletree amp.

Thanks!

 

[cheemo]

Many who own the Ear+HD pair them with the RS1's and the synergy takes the Grados to the next level. To my ears, I heard better instrument separation and increase of detail with more bass impact, some songs were a bit hot on the treble end but this was with the stock tube. I rolled in a different tube and the sound change to more of a warm presentation, also another variable will be what model RS1 you own as the variations are noted in the forum. Good luck.

 

[SemiAudiophile]

both are classy looking amps. the Woo having a more industrial, contemporary look, while the Mapletree has a more classic, vintage look. i prefer the vintage, classic look. goes well with Grado's.