Domesticating & Documenting the Little Bear

the thin end of the wedge
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draganm
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Re: Domesticating & Documenting the Little Bear

Post by draganm » 28 Mar 2018 18:42

dnepro wrote: 1) Is changing the tubes likely to mellow out the harshness of the uppermost range?
2) Is it necessary to change all the tubes to 12ax7, or could I replace the tube with the most significant effect on tone as a trial (leaving the others as 6n2's) and switch the others later if improved?
3) Is matching tubes necessary - or is this a guitar amp issue?
4) Is purchasing 'tested' tubes highly recommended, or a disposable luxury? (Ignoring the obvious irony that this whole pursuit is a disposable luxury)

I suppose there is also the question of upgrading the rectifier tube, which although I understand should theoretically have limited impact on sound, I have read some people think it does.
Many Thanks,

David
well congrats on the no-hum issue, that one seems to be real hit or miss with users even with the same version of T10-11 , etc.

I'll take crack at your 4 but opinions ill vary

1) I would not expect a significant tonal balance shift from tube-rolling to a boutique tube versus Asian. I've never done it with my T10, but I noticed very little difference in the past. I put in a very expensive NOS 1950's GE 12AX7 that cost me $75 (tested to be at spec.)
now selling for $119.
https://tubedepot.com/products/jan-ge-12ax7-long-plate
into a Bellari and difference was so subtle as to be barely noticeable. My T10 uses a stock Chinese 12AX7 and the tonal balance is beautiful,

so might it be a tube type issue, yes possibly,

versus a tube manufacturer issue? unlikely IMHO.

2) The tube that does the most work in this circuit is the first one, the one farthest from the RCA output jacks. Can you put a 12AX7 here and switch while leaving all the others 6N2, probably, but others here would know better.

3)I do not see how matching tubes in a circuit where they are run in series can make any difference at all.

4)My $75. GE tube really felt like a huge waste of money, and still does. Next step down is some Amperex bugle boys at $120. for the set of 3, still too much. My next tubes, after the stock ones go bad, is a set of Russian Gold Lions and they will need to be a good deal, like $60. for all 3 .

draganm
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Re: Domesticating & Documenting the Little Bear

Post by draganm » 28 Mar 2018 18:49

I better stop reading this thread before I do something stupid............ like spend money :mrgreen:
But I found this , awfully tempting for 25 bucks
https://tubedepot.com/products/jj-ecc80 ... acuum-tube
For Audiophiles - Combining a noise canceling spiral wound filament with oversized plates and rugged construction, this tube provides a forward sounding, full-bodied low end response with a weighty, dynamic midrange easily compared to the Telefunken ECC803s. Its high end response is controlled yet warm with a very pleasant depth of field that extends the full sonic landscape. This tube is perfect as the first gain stage in most HiFi audio equipment. Especially useful for taming brittle digital sources such as MP3, CD and DVD players.

Devoid of harshness, this tube is easily the most listenable preamp tube in production. And with hand selected quality and solid, proven performance, it is a wonderfully refreshing addition to the 12AX7 family of tubes. Your equipment will take on new character across the entire audio spectrum once you install this tube. This tube gets our vote as one of the best new tubes in production today.

For Musicians - The depth of low end and forward midrange from this tube is astonishing. It has a level of "ummph" that must be heard to believe. There is so much more tone from this tube that some amps struggle to handle the boost in performance from this tube. This is not a generic low gain 12AX7, this is pure muscle. And if your amp can hold on, it's worth trying in all positions just to see what can be awakened in your amp.

At the end of the preamp tube chain, the JJ ECC803S Gold Pin makes a phenomenal phase inverter tube. Its oversized plates give the additional drive needed to really push the power tubes to their fullest potential. This is pure electrical adrenaline; it's as if excess horsepower was squeezed into the glass. For whatever music you play, this tube will surprise you.

draganm
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Re: Domesticating & Documenting the Little Bear

Post by draganm » 28 Mar 2018 18:51

wow, check this out. Might be pure malarky but fun to look at. I don't remeber this from back when I wasted $75. with them

https://tubedepot.com/tube-comparison-tool

draganm
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Re: Domesticating & Documenting the Little Bear

Post by draganm » 28 Mar 2018 22:52

judging by that chart they put up, the Mullard made in Russia seems to hit all the right qualities (bet you thought I was going to say "notes), for only $17.

it's funny that they recommend the gold lion JJ ECC803S as "audiophile" but the cheaper Mullard scores higher overall with better sensitivity and lower noise floor

I might just have to try one
https://tubedepot.com/products/mullard- ... acuum-tube

Milky_5343
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Re: Domesticating & Documenting the Little Bear

Post by Milky_5343 » 28 Mar 2018 22:57

The OM10 can be a little "top endy", so the LB might just be faithfully reproducing what it "hears". Having said that, yes, there can be some benefits from changing the valves (yeah, I call them that too - not "tubes"). You will always get fan clubs popping up who will swear that brand X is definitely better than brand Y, but, at some point it all becomes academic. Are your tweeters a little "over-bright"? Is the room properly tuned? Is your amplifier EQ properly adjusted?

I have one of the original LBs, so, without a lot of messing around, 12AX7s weren't an option. The later models provided on-board switches to make the change from 6N2 to 12AX7 easier. I wouldn't mix'n'match the two types - either swap the lot to 12AX7, or stay with the 6N2, but not a mix of the two. "NOS" simply means "New Old Stock", so they were produced back in the days when valves were boss, and have sat on a shelf ever since.

I swapped the Chinese 6N2 to some Soviet Rockets (I got a job lot of 10 x 6N2Ps on eBay), and I think it did sound "mellower", but it was hair-splitting without accurate before/after measurements with proper equipment. I'm also 69 years old, to the "listening platform" may not be quite as level as yours.

There is also the question of "burn-in". ALL valves sound better after a period of use - up to 20 hours or so. This means that you won't realise their full potential until you have put something like twenty full LPs through them. Then they will gradually start to deteriorate, so it is really hard to define the perfect "sweet spot" where the valve fully burned in to where it starts to drop off in efficiency, and even valves of the same brand will decay at different rates.

The notion of pre-testing valves can mean anything from simply checking that the filament lights up, to some sort of matching based on an output reading or some other measurement. It won't necessarily guarantee better audio quality, but may save you money by not taking delivery of a "dud" or two.

"Matching" valves is more important in "push-pull" circuits, where one half of the valves amplifies the forward going pulse, and the other half amplifies the reverse. It stands to reason that, if one half is working better than the other, you will have some sort of signal distortion or disparity, so matched pairs are important in that situation, and many, many musical instrument amps have this configuration. In the LB, this is less of an issue.

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Re: Domesticating & Documenting the Little Bear

Post by draganm » 28 Mar 2018 23:08

ok, but if the Tube Depot I linked to changed their name to the " Valve Depot" then wouldn't they start getting a bunch of calls from Automotive guys rebuilding their cylinder heads? :mrgreen:

He did imply that the bright top end was a result of the new LB Phono-pre.

Dnepro how does your digital source sound compared to Analog,or Pre LB, same brightness?

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Re: Domesticating & Documenting the Little Bear

Post by dnepro » 02 Apr 2018 01:11

Thanks for all of the above, I read it all with great interest! To answer a few questions:

The longstanding Marantz amp/kef speaker set up has always been a touch bright, and the treble invariably dialled down a little. Also,I have no doubt that the room is less than optimally set up given it's lopsided shape, victorian age layout complete with woodburner!

With regards to the amp EQ, I have frequently been running it 'direct', perhaps labouring under the delusion that the record player/valve pre-amp combo would magically combine to render EQ meddling unnecessary!

With regards to valve selection - I had come across that tubedepot comparison - interesting to see the emphasis they give with regards to valves having different tonal characteristics - and clearly different to the experience of some here.

In the end I guess it just comes down to suck it and see - so I have ordered some 6n2 voshkod rockets, for much less than I was considering spending! Seemed like a good way to determine the effect of valves on the sound of my system without breaking the bank. Thanks for the recommendation. Depending on the nature of the change in sound, I may return to the comparison at a later date, and when funds are avaiable!

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Re: Domesticating & Documenting the Little Bear

Post by Milky_5343 » 02 Apr 2018 01:48

The whole point of EQ is to compensate for component mismatch and the tonal qualities of the room. A simple bass/treble setup can help, but, if you were able to analyse the room with a microphone placed where you sit and fed into Real Time Analyser software, you would find that there will be peaks and troughs in the audio spectrum, based on the amount of hard and soft furnishings, shape of the room and even the characteristics of the playback equipment, particularly the speakers.
Some of these can be cleaned up with drapes, carpet or re-positioning of the speakers and other furniture, but some notches or peaks would need to be EQd out through a graphic equaliser, which addresses separate ranges within the spectrum. I'm not suggesting that you go down this route, but there is no shame in having and using tone management equipment, because rooms are rarely designed to be the perfect listening environment.

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Re: Domesticating & Documenting the Little Bear

Post by draganm » 05 Apr 2018 01:32

Milky_5343 wrote:The whole point of EQ is to compensate for component mismatch and the tonal qualities of the room.
The room could certainly be part of it, they say when you listen to a hi-fi system you hear the room first and then the equipment, or another way of putting it, the room usually is the biggest contributor to the sound of your system. I don't remember the Kef's being overly forward or bright sounding speakers, but I've never owned a pair. It is almost without doubt not the Marantz as they are known for a softer sound.

Dnepro are you using any sound absorbing panels in your room. Do a search for " first reflection point in listening room" . A reflection here will definitely exaggerate the upper mid range and have a fatiguing effect. It's not so much a tonal balance issue but 2 sets of sound waves hitting your ear a fraction of a second apart. Often this is what people are usually blaming when they complain about an overly bright system.

I fought this issue in my room even after putting in acoustic treatment. IT made it better, but my system never sounded right. Went round and round, buying /selling gear, and finally found the problem in my speaker cables, which were lab tested as high capacitance, a huge problem in audio. I found it by chance after reading a review of my cables and the symptoms they described. Couldn't be happier now, but it took years and there were times when I just didn't use my TT. I never blame someone now when they say " I use headphones" :mrgreen:

Come to think of it, headphones would at least eliminate or confirm if the problem is the cartridge or phono pre-amp. Got a pair?

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Re: Domesticating & Documenting the Little Bear

Post by Milky_5343 » 05 Apr 2018 03:14

That's making quite a few assumptions that the HP are frequency linear as well, but I take your point that there would certainly be less "room colouration" through cans.

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Re: Domesticating & Documenting the Little Bear

Post by draganm » 05 Apr 2018 06:09

Milky_5343 wrote:That's making quite a few assumptions that the HP are frequency linear as well, but I take your point that there would certainly be less "room colouration" through cans.
true,
but I think any decent set of headphones will be fairly well balanced. It's really easy to design when your not dealing with speaker cabinets, multiple drivers, cross-over networks, phase inversion at different frequencies, dispersion,into a room. etc.
It's worth a try if a pair are readily available

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Re: Domesticating & Documenting the Little Bear

Post by dgw1972 » 12 Apr 2018 00:44

Just got my little bear t10, v2.6 with the toroidal transformer. Im getting a noise from the left output channel, not so much a hum but a shhh shhh shhh type of noise. If i switch to one of my other preamps the noise goes away. Also, if I swap left and right rca cables the noise follows. Its for sure coming from the left output on the little bear. Does anyone have any idea what else I can check or has anyone else had this happen? The right side output from the LB is as quiet as it should be.

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Re: Domesticating & Documenting the Little Bear

Post by Coffee Phil » 12 Apr 2018 01:48

Hi Dgw1972,

It could be a noisy resistor, but in the interest of simple things first try swapping the tubes around. The first and second stages are the most critical. Swap the third stage tube into those positions to see if it makes a difference.

Phil

dgw1972 wrote:Just got my little bear t10, v2.6 with the toroidal transformer. Im getting a noise from the left output channel, not so much a hum but a shhh shhh shhh type of noise. If i switch to one of my other preamps the noise goes away. Also, if I swap left and right rca cables the noise follows. Its for sure coming from the left output on the little bear. Does anyone have any idea what else I can check or has anyone else had this happen? The right side output from the LB is as quiet as it should be.
St[album]41015[album]

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Re: Domesticating & Documenting the Little Bear

Post by dgw1972 » 12 Apr 2018 02:06

Hi Phil, thanks for the response. I swapped the stock chinese tubes back in and its good. I guess one of the russian rocket tubes I got was bad.

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Re: Domesticating & Documenting the Little Bear

Post by dgw1972 » 15 Apr 2018 00:56

Ok, new question... I just got some sovtek 12ax7lps tubes and installed them. I flipped the switches from 6np to 12ax7 and turned on the power. The rectifier still gets power but none of the 12ax7s are lighting up. Whats up with that? Any ideas?

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