[Tom Steed]

This was just an example, the chances are if you bought 2 they'd be NOS from the same batch. A matched pair will be more expensive.

 

[hjribeiro]

This was just an example, the chances are if you bought 2 they'd be NOS from the same batch. A matched pair will be more expensive.

They're on their way

 

[Slipmyster]

Isn't it better to buy matched pairs?

I bought two matched pair. Tom Steed is right they will cost a bit more for the matched tubes bit how much will depend on the seller

 

[erich6]

Refer to earlier posts in this thread for detailed description of tube sound differences. Amperex NOS will provide better bass.

 

[dhaninugraha]

Just pulled the trigger on this amp. Wonder how the rMBP > Hifiman HM-101 > NS08E > HD25 combo would sound.

 

[sup27606]

I got Mullard CV3998 E180F 6688 Vacuum Tubes matched pair from eBay last year. Costed me $25 for the pair. It seems, the price has gone down as of now. Matched pairs of same specs are available now for $18 shipped at eBay.

These tubes seem to have good bass without being boomy, and great soundstage both in width and breadth. The soundstage with Sennheiser 6XX is definitely bigger than what I get from Schiit Jotunheim. Also, the clarity is not any less either. I really like to hear live recordings through the Nobsound, because the bigger soundstage gives better feeling of the auditorium. I am feeding the amp from Mimby.

Does anyone know, how to solve the pops and cracks that occasionally occurs in the sound? Are they the tubes or the power supply? I notice, they always happen in the left earpiece.

 

[Slipmyster]

I got Mullard CV3998 E180F 6688 Vacuum Tubes matched pair from eBay last year. Costed me $25 for the pair. It seems, the price has gone down as of now. Matched pairs of same specs are available now for $18 shipped at eBay.

These tubes seem to have good bass without being boomy, and great soundstage both in width and breadth. The soundstage with Sennheiser 6XX is definitely bigger than what I get from Schiit Jotunheim. Also, the clarity is not any less either. I really like to hear live recordings through the Nobsound, because the bigger soundstage gives better feeling of the auditorium. I am feeding the amp from Mimby.

Does anyone know, how to solve the pops and cracks that occasionally occurs in the sound? Are they the tubes or the power supply? I notice, they always happen in the left earpiece.

Do you have a different pair of tubes to try in place of the mullard's.
Have you try'd re seating the tubes to make sure you have a clean connection.
May be someone with more experience may be able to give more advice. Hope you get it sorted.

 

[edulov]

About noise and cracks there is an easier solution. Swap the tubes and keep using them for a while till I'll get this effect again. Channel will change - one tube has more problems and you need to find a replacement. Otherwise the problem is outside. So, try to connect Nob' to other music gear and keep hearing. If the sound is clear, then your initial PC is guilty, still getting weird sounds - Nob's PSU (Most probably).
In the case of PC I've seen 3 most frequent problem origins: computer PSU, bad amp's input jack connection of audio cable (should not be a case if cable is not moving at the moment when cracks appear). And the third - problems with USB port if you have an usb DAC (the case of internal of internal sound card I shall mention at the end). Here you have different options to check. The best one - use Nob' for a while without computer just to ensure that problems have a PC as an origin.
If it is a case, most parasite sounds I was getting when PC was heavily loaded while playing audio. Normally, assigning quite bigger audio buffer size in player solves the problem. But if you are shure that cracks were appearing even at nearly idle PC state, the problem is in USB port, but once again, it could be caused by computer PSU. Here you need to try another USB port to confirm if it is a motherboard problem (still not 100%) or computer PSU. Laptop owners have lesser options, but as if in the case of the internal sound card, try to install the other, used one. Even a cheap one.

May be you will forge another sequence of checks depending on your computer/audio gear setup. Sadly, if the tube swap does not give an answer it will take time checking options unless problems appear for heavily loaded PC only. Just for interest, tell us later what happend in your case.

BTW, don't laugh at bad jack connection, especially if the Nob position is not permanent and cables somehow could be touched/displaced occasionally.

 

[Tom Steed]

I bought two matched pair. Tom Steed is right they will cost a bit more for the matched tubes bit how much will depend on the seller

I also put a pair of these in, JRC 4558D. These are inexpensive high quality op amps and they sound great.

 

[Slipmyster]

I also put a pair of these in, JRC 4558D. These are inexpensive high quality op amps and they sound great.

Thanks for the information I've bin thinking of trying to roll the op amp chips but wasn't sure witch ones would work and didn't want to risk doing any damage.
Thanks again I'll get a pair. Do op amps need to be matched ?

 

[Tom Steed]

no, they should all be manufactured to the same spec. I would buy 2 from the same supplier though. copy this item number into fleabay, they're the pair i got: 182581579004

 

[Slipmyster]

B

no, they should all be manufactured to the same spec. I would buy 2 from the same supplier though. copy this item number into fleabay, they're the pair i got: 182581579004

no, they should all be manufactured to the same spec. I would buy 2 from the same supplier though. copy this item number into fleabay, they're the pair i got: 182581579004

Brilliant. Thank you very much

 

[edulov]

Matched not necesarilly means the same fabric or lot. Several electric parameters measured by special test unit must be very close to avoid bias for L/R. Since it takes time to proceed and make groups (some electrical devices need more than 2 equal tubes), usually they cost more, or the same seller makes quality batches.
You can discover the final result recording the amp's output with the same L/R setting at sound origin. Or using RMAA "live", it has this special option to adjust recording inputs.

 

[sup27606]

About noise and cracks there is an easier solution. Swap the tubes and keep using them for a while till I'll get this effect again. Channel will change - one tube has more problems and you need to find a replacement. Otherwise the problem is outside. So, try to connect Nob' to other music gear and keep hearing. If the sound is clear, then your initial PC is guilty, still getting weird sounds - Nob's PSU (Most probably).
In the case of PC I've seen 3 most frequent problem origins: computer PSU, bad amp's input jack connection of audio cable (should not be a case if cable is not moving at the moment when cracks appear). And the third - problems with USB port if you have an usb DAC (the case of internal of internal sound card I shall mention at the end). Here you have different options to check. The best one - use Nob' for a while without computer just to ensure that problems have a PC as an origin.
If it is a case, most parasite sounds I was getting when PC was heavily loaded while playing audio. Normally, assigning quite bigger audio buffer size in player solves the problem. But if you are shure that cracks were appearing even at nearly idle PC state, the problem is in USB port, but once again, it could be caused by computer PSU. Here you need to try another USB port to confirm if it is a motherboard problem (still not 100%) or computer PSU. Laptop owners have lesser options, but as if in the case of the internal sound card, try to install the other, used one. Even a cheap one.

May be you will forge another sequence of checks depending on your computer/audio gear setup. Sadly, if the tube swap does not give an answer it will take time checking options unless problems appear for heavily loaded PC only. Just for interest, tell us later what happend in your case.

BTW, don't laugh at bad jack connection, especially if the Nob position is not permanent and cables somehow could be touched/displaced occasionally.

Thanks for all the suggestions. Good to remember if such problems happen in future. I don't know why, but the cracking sounds went away the next day. I have been listening for several days, and it hasn't come back. May be the jacks, that would be my guess.

Based on your impression couple of pages back, I am trying to find a pair of Amperex JEP 6688 tubes (I use the Mullards currently) online, but seems hard to find for cheap. How much should I expect to pay for a pair from the same batch (not necessarily matched)?

I am almost exclusively using the Sennheiser 6XX with the Nobsound. My personal view is, the Sennheiser synergizes very well with the Nobsound, fed from a Mimby. The other headphone I tried, Audeze EL-8 didn't sound so well, which explains the frequency curves for low impedance headphones. The soundstage from the Sennheiser/Nobsound combo is superb! and I came to this conclusion after hours of listening with a variety of music. To my ears, it surpasses the soundstage from the Schiit Jotunheim even in the balanced configuration. With the Nobsound, the sound has a beautiful smoothness to it without sacrificing details. Due to the smoothness, the micro-details are in fact more audible, and music can be enjoyed at low volume without losing impact. The sound almost feels magical, with subtle positional cues and a voluminous soundstage. None of the sound overpowers others or seem out of place. Vocals ARE amazing. I just feel, a slight sparkle (and I mean very little) in the treble could help in some of the tracks, for instance with the string instruments. Thats why, I am looking at the Amperex JEP.

 

[edulov]

Reasonable Ohm discussions is difficult to led w/o measuring, but to my hearing greater Ohm - sounds better. At least 32Ohm. Lower ones produces lifeless effect to me and less bass control.