ChopperCharles said:
Charles;
if volume stays the same, but frequency response changed, it means that amplification factor changed so feedback loop gain had been changed as the result. With no feedback you would be able to measure differences in gain. It means different specs. No magic here. It's not about Garry Potter, it is about dumb plain physics and mathematics.
With regarding tubes sounding different. Has anyone ever plotted tube curves for tubes for the same type from the e.g 1950's to current production? Are they the same?
Is the metallurgy / chemistry the same? Could things like these cause the differences which we hear?
Is the metallurgy / chemistry the same? Could things like these cause the differences which we hear?
Andrewbee said:
I haven't done this type of testing specifically. However, I've done designs using RCA plate characteristic curves from the late 1940s -- 1950s when the various types were introduced. In those designs, I've used current production Sovtek 6SL7s and 6SN7s, and gotten errors of both DC and AC measurements that have been within +/- 5.0% of the design nominal values for plate currents, grid bias, gain and frequency response. As for the Sovtek's, they adhere quite closely to the specs. I don't see any detectable microphony from the Sovetk's either.
Andrewbee said:
How about we start by testing these old tubes in a tube tester.When you get a 30 yr old tube,how do you know its good? The people selling say it good but do they test it? We know that the chinese tubes are new so they should all have the same characteristics. But old tubes that have been used may not be up to speck. Rather than trying to plot tube characteristics ,we should start by testing the old tubes in a tube tester.Can you do that chopper charles?This would be a logical point to start.
🙂
Wavebourn said:
This isn't logical. Your conclusion seems to reflect your feelings on the subject. You don't account for resonance or anything else.
I see no reason to doubt what ChopperCharles is saying, furthermore, I believe him.
jnb said:
I believe too, but I have at least a logical explanation instead of magical one. 😀 Electrons have an equal speed for all frequencies in an audio band, and tubes don't care what frequencies to distort. 😀
A triode stage may roll of highs if resistances in grid and plate networks are too high for capacitances (including Miller capacitance), triode stage may roll off lows if resistance in cathode is too high and blocking capacitance is too small, but it is magical assumption to say that some tubes cut off midle frequencies while other tubes don't.
What can highlight middles, is a speaker, especially when it has a crossover. If output resistance of the amp is higher middles are highlighted more. The more gain preamp tubes have, the deeper is feedback, the lower is output resistance, the less middles are highlighted.
Do you hear me now? 😉
jnb said:
We are not doubting what chopper charles says either. We are tring to find out why two tubes with the same number sound different.There has to be a reason. "logic dictates it"(spock)
🙂
Wavebourne, your suggestions are possible. My suggestion of microphonics is too; it is my opinion in this case. Perhaps cases of both exist. Neither is magic.
Do you hear me now? 😉
Do you hear me now? 😉
jnb said:
Yes, but your suggestion is wrong: microphonic effect is specified in millivolts. And it may be out of specs as well.
Well, if you're sure a mV spec is all there is to it, I guess we should just agree to disagree? 😎
jnb said:
I presume you mean resonances in the audio band (not r.f. 🙂 ). Surely such needs to be excited before any evidence is shown? In this respect there can be quite a difference between a static docile bench test and responce during a full-blast racket. Thus I do not doubt what you are saying, but let us keep the circumstances in mind. Those different sounding tubes - were they new or all shaken up? I don't know what degree of accelerations operate on tubes in disco circumstances (not my field of experience), but special tubes are made with also a vibration spec., so there is a limit.
On your earlier post re specs and plate curves, I include both when I mention specs in general.
If of any interest, I had occasion to compare some 26 unused 6L6s over the last year or so: 8 x 6L6GC: GEC (NOS); 8 x 6L6EH, 2 x 6L6GC RCA black plate (NOS), 6 x 6L6WXT and 2 x 6L6GB (Ultron). They were all within 10% of one another (mostly closer) at nominal Ia = 75mA, on 330V h.t., fixed bias.
jnb said:
Let's ask Charley to knock tubes by a screwdriver's tip and report differences. If Chinese one rings on that "middle frequency" but a NOS one does not it means he have found that ghost following by your directions. 😉
Many manufacturers, US and others have taken liberty with tube construction over the years. The specs and the curves shown in tube manuals are usually averages from a small lot of tubes made before the tube was released for production. Over the years production may have moved to a different location, or the production equipment may have been changed. Tooling wears out and gets replaced. Did you ever wonder how some tubes were manufactured over a 30 or 40 year span, but the curves in the tube manual were never changed.
As the production of vacuum tubes declined the manufacturers took even greater liberty with what they put inside the glass. Some tubes had the guts from an entirely different tube put inside them. This is especially true with TV sweep tubes, and tubes made for military contracts. The later version may have similar specs at the intended operating point, but is likely to be radically different in another circuit.
I have been testing several versions of 6EM7 dual triodes lately. There are a few different versions of these and the low Mu triodes are indeed quite different. They measure different as well with a Mu varying from 4 to 7 under the same conditions. These have an obvious difference in gain in a circuit without feedback, but may sound similar in a high feedback circuit where open loop gain variations are not as important.
I have seen several cases of some creative "tube stuffing" but none as far out as this one. The story goes like this. Sylvania needed to make some 6B4G's to satisfy a military contract. The 6B4G is a DHT, but Sylvania had already ceased production of DHT's. They found a suitable beam tetrode, the 6AV5GA which is a TV sweep tube and simply wired the base up to the same pinout as the 6B4G. Do you think this will sound the same as a 6B4G in your DHT amp? Are the curves identical to the 6B4G? I didn't think so. This is obviously the worst case, but there are differences in tubes with the same number stamped on the glass.
And yes, I have popped a pair of these into a 6B4 amp. They have far more bass than the real 6B4G's, but give up some of the DHT detail.
As the production of vacuum tubes declined the manufacturers took even greater liberty with what they put inside the glass. Some tubes had the guts from an entirely different tube put inside them. This is especially true with TV sweep tubes, and tubes made for military contracts. The later version may have similar specs at the intended operating point, but is likely to be radically different in another circuit.
I have been testing several versions of 6EM7 dual triodes lately. There are a few different versions of these and the low Mu triodes are indeed quite different. They measure different as well with a Mu varying from 4 to 7 under the same conditions. These have an obvious difference in gain in a circuit without feedback, but may sound similar in a high feedback circuit where open loop gain variations are not as important.
I have seen several cases of some creative "tube stuffing" but none as far out as this one. The story goes like this. Sylvania needed to make some 6B4G's to satisfy a military contract. The 6B4G is a DHT, but Sylvania had already ceased production of DHT's. They found a suitable beam tetrode, the 6AV5GA which is a TV sweep tube and simply wired the base up to the same pinout as the 6B4G. Do you think this will sound the same as a 6B4G in your DHT amp? Are the curves identical to the 6B4G? I didn't think so. This is obviously the worst case, but there are differences in tubes with the same number stamped on the glass.
And yes, I have popped a pair of these into a 6B4 amp. They have far more bass than the real 6B4G's, but give up some of the DHT detail.
Attachments
Johan Potgieter said:
One had had a handful of hours from NIB and the other two were low hours pulls from quiet environments.
Wavebourne said:
The amplification factor/open loop gain issue can't apply in this case because I was not using feedback. Levels sounded the same to my ears.
Johan Potgieter said:
I noticed you mentioned a low vibration spec but didn't suggest thermal flexing of the plate, or magnetic forces on steel components.
Wavebourne said:
Well, that should do some good 🙄
Lets get back to basics! Can chopper charles test the two tubes to see if one is defective.This sound like a place to start instead of speculating on what the difference might be.
I do own one since mid '07 and can tell you
Hi Chopper Charlie!
I owned the Yaqin MC100B since august '07 and let me tell you.
Tube rolling pays off.
I noticed my amp overhating a little bit so I purchased a VAriac transformer for it and run it to 110 Volts with much success, my local grid here goes from 119 Volts at 5 or 6 PM to 124 Volts (RMS) at about 9PM and later M-F. these Chinese amps as wonderful as they are they need to be stabilized at 110 volts.
now the looks are absoluetly fantastic metalworks second to none! also they can be compared to tube gear costing many . . many!! thousands of $.I am going to try to save you about 9 months of efforts of R&D of tube rolling and about $900 worth of tubes . . . here it goes.
Best tube for output on the Yaqin in the original Shuguang KT88-98 if it did not come with them or something different the ebst one is the Sophia ELectric version called GEKT-88 about $175 for a perfectly matched quad set.
for phase splitter tubes use Sylvania or RCA or Tung-Sol 6SN7 (buy online for $5 to $20 a piece NOS) and forget the chinese that came with it they're garbage . . really, I peronally am using Sylvania 1950's 6SN7's black base and tungs sol brown base matched per channel (1 and 1 of each mirror pair)
Now for 12AX7 tubes you can use the original Shuguangs 12AX7B's that came with the units they're a little bright and brittle sounding, for real Kick-Butt bass get a pair of Mullards ECC-83 NOS, they're expensive but they are the best bass period.
I found my flavor to be a little bit more balanced towards te mids more bloomy and more pristine top end and that flavor is definetely Tungrams ECC-83 made in Hungary vintage 1970's 1960's if you can get them ($$)
The Mullards are a little too basey for me but I bought the pair perfectly matched and testing like new if thsi si what you want I'll be happy to sell you my pair.
I also bought reissue mullards (not as god), Telefunkens ECC-83 too rich for my blood, Sylvanias black plates, AMperex 12AX7's, other mullards NOS vintages, also GE 12AX7 1960's.
ELectro harmonics and Slovak made Ei or beter known now as J/J tubes these are pre conflict late 70's early 80's I believe.
All of them did something good or another.
For transparency and liquidity of mids definetley the Telefunkens, Tungs-Rams and Amperex, the EH and Ei and GE's are too soft in the bass.
Again the best bass by far has been the Mullards Blackburn 1960's.
all the tubes I mentioned I personally bought or got loaners form tube freak friends, os i have a clear understanding how they sound and operate in the Yaqin amplifier.
I still keep the mulllards, the EH, the Ei, the chinese 12AX7B's (who's going to buy my chinese tubes???) and I bought 2 sets of Tungsrams ECC-83 just in case they get very difficult to get in the near future.
Do not wate time with the Golden Lyon reissues, do nto very well n our amp, a lot of hoopla to them.
Hope this helps a little;
Silver interconnects and speaker cables respond very very well to the amp and vice versa it is just that speaker pair of silver cost a lot more than the amp itself . .. .
I use a pair of Kimber 4AG with them ($4,000 for the pair), and Kimber KCAG for interconnects form the DAC to the Yaqin amp also another $700 worth of silver cables.
Crazy?? yes but in love with my tubes!!!!
I can tell you all bout them each and every one of them
Hi Chopper Charlie!
I owned the Yaqin MC100B since august '07 and let me tell you.
Tube rolling pays off.
I noticed my amp overhating a little bit so I purchased a VAriac transformer for it and run it to 110 Volts with much success, my local grid here goes from 119 Volts at 5 or 6 PM to 124 Volts (RMS) at about 9PM and later M-F. these Chinese amps as wonderful as they are they need to be stabilized at 110 volts.
now the looks are absoluetly fantastic metalworks second to none! also they can be compared to tube gear costing many . . many!! thousands of $.I am going to try to save you about 9 months of efforts of R&D of tube rolling and about $900 worth of tubes . . . here it goes.
Best tube for output on the Yaqin in the original Shuguang KT88-98 if it did not come with them or something different the ebst one is the Sophia ELectric version called GEKT-88 about $175 for a perfectly matched quad set.
for phase splitter tubes use Sylvania or RCA or Tung-Sol 6SN7 (buy online for $5 to $20 a piece NOS) and forget the chinese that came with it they're garbage . . really, I peronally am using Sylvania 1950's 6SN7's black base and tungs sol brown base matched per channel (1 and 1 of each mirror pair)
Now for 12AX7 tubes you can use the original Shuguangs 12AX7B's that came with the units they're a little bright and brittle sounding, for real Kick-Butt bass get a pair of Mullards ECC-83 NOS, they're expensive but they are the best bass period.
I found my flavor to be a little bit more balanced towards te mids more bloomy and more pristine top end and that flavor is definetely Tungrams ECC-83 made in Hungary vintage 1970's 1960's if you can get them ($$)
The Mullards are a little too basey for me but I bought the pair perfectly matched and testing like new if thsi si what you want I'll be happy to sell you my pair.
I also bought reissue mullards (not as god), Telefunkens ECC-83 too rich for my blood, Sylvanias black plates, AMperex 12AX7's, other mullards NOS vintages, also GE 12AX7 1960's.
ELectro harmonics and Slovak made Ei or beter known now as J/J tubes these are pre conflict late 70's early 80's I believe.
All of them did something good or another.
For transparency and liquidity of mids definetley the Telefunkens, Tungs-Rams and Amperex, the EH and Ei and GE's are too soft in the bass.
Again the best bass by far has been the Mullards Blackburn 1960's.
all the tubes I mentioned I personally bought or got loaners form tube freak friends, os i have a clear understanding how they sound and operate in the Yaqin amplifier.
I still keep the mulllards, the EH, the Ei, the chinese 12AX7B's (who's going to buy my chinese tubes???) and I bought 2 sets of Tungsrams ECC-83 just in case they get very difficult to get in the near future.
Do not wate time with the Golden Lyon reissues, do nto very well n our amp, a lot of hoopla to them.
Hope this helps a little;
Silver interconnects and speaker cables respond very very well to the amp and vice versa it is just that speaker pair of silver cost a lot more than the amp itself . .. .
I use a pair of Kimber 4AG with them ($4,000 for the pair), and Kimber KCAG for interconnects form the DAC to the Yaqin amp also another $700 worth of silver cables.
Crazy?? yes but in love with my tubes!!!!
I can tell you all bout them each and every one of them
I came across this thread and wow! You can turn a tennis ball inside out on paper, but lets see you do that in real life, now if you pull you heads out of the sand you might be able to hear better. 😀
I've always thought that a good amplifier design showed off tube charateristics due to it's nutrality rather than a toned amp masking the effects of the tubes.
I almost agree on all aspects with Gonzalo.
GEKT88-98 especially the flate plate ones are the best for this amp that I've tried, but I haven't tried the Gold lions yet!
6SN7's Now I recieved 6n8p military with the red military star on them if that makes a difference, and I have to say tight responsive realism top to bottom, dynamic with a bar room soundstage, so not as deep as say a sylvania chrome dome, but one of my favorites, does drums like no other tube I've heard. I like to mix it with RCA black plate bottom getter in stage one or CBS 6sn7GTB angled tri-plates in stage two, but I almost always have it in there. As these are my 3 favorite tubes that all have very decent bass, but the biggest, clear bass is my Sylvania Chrome dome green label, but I find it thin and dry mids with a very nice treble very responsive and awesome soundstage.
Now for 12ax7 I've been sort of divulging into 5751's (I only have 3 types so far) which work well in this amp, and I'm prefering them to my 12ax7's now. All I have tried so far are the tungsol, thick and palpable, GE black plates, clear and soundstage and sylvania 2-mica grey plates, warm and airy, which are my wifes favorites (she's a musician), I can't decide which I like better. 12ax7 "fuzz" is more like an aura presented around the image. Read up Joes Tube lore, I pretty well agree so far with what he's said. But there are nice 12ax7's. Also try the 6SN7 archive for 6sn7 reference.
I've always thought that a good amplifier design showed off tube charateristics due to it's nutrality rather than a toned amp masking the effects of the tubes.
I almost agree on all aspects with Gonzalo.
GEKT88-98 especially the flate plate ones are the best for this amp that I've tried, but I haven't tried the Gold lions yet!
6SN7's Now I recieved 6n8p military with the red military star on them if that makes a difference, and I have to say tight responsive realism top to bottom, dynamic with a bar room soundstage, so not as deep as say a sylvania chrome dome, but one of my favorites, does drums like no other tube I've heard. I like to mix it with RCA black plate bottom getter in stage one or CBS 6sn7GTB angled tri-plates in stage two, but I almost always have it in there. As these are my 3 favorite tubes that all have very decent bass, but the biggest, clear bass is my Sylvania Chrome dome green label, but I find it thin and dry mids with a very nice treble very responsive and awesome soundstage.
Now for 12ax7 I've been sort of divulging into 5751's (I only have 3 types so far) which work well in this amp, and I'm prefering them to my 12ax7's now. All I have tried so far are the tungsol, thick and palpable, GE black plates, clear and soundstage and sylvania 2-mica grey plates, warm and airy, which are my wifes favorites (she's a musician), I can't decide which I like better. 12ax7 "fuzz" is more like an aura presented around the image. Read up Joes Tube lore, I pretty well agree so far with what he's said. But there are nice 12ax7's. Also try the 6SN7 archive for 6sn7 reference.
Can't answer your question for your specific amp, but YES tubes DO
sound different, some equipment will show it more then others and
not all your 'BEST" sounding tubes will sound best in every piece.
We've done plenty of tube rolling around our audio club and some
are quite amazed at how different the same type tube can sound
when various different brands and constructions are tested.
Heck even a Tube Cd player that uses a 5AR4 in the power supply
had a significant change in sound when rolling different 5AR4's.
So either people who haven't heard the difference haven't done
a lot of rolling with an open mind or possibly enough feedback in
those units that won't let the tube character shine through.
I prefer to use small amounts of feedback and around less stages
gives me the best sound performance and tube rolling works well.
Just what I've experienced and how well it works for me. YMMV
sound different, some equipment will show it more then others and
not all your 'BEST" sounding tubes will sound best in every piece.
We've done plenty of tube rolling around our audio club and some
are quite amazed at how different the same type tube can sound
when various different brands and constructions are tested.
Heck even a Tube Cd player that uses a 5AR4 in the power supply
had a significant change in sound when rolling different 5AR4's.
So either people who haven't heard the difference haven't done
a lot of rolling with an open mind or possibly enough feedback in
those units that won't let the tube character shine through.
I prefer to use small amounts of feedback and around less stages
gives me the best sound performance and tube rolling works well.
Just what I've experienced and how well it works for me. YMMV
Gonzalo, I have the Sylvania chrome dome 6sn7's with the black base, (NOS, 1945 or so) and they're absolutely wonderful. I'm still running the original KT88 output tubes, and I also have a pair of Electro Harmonix reissue 12AX7's.
I'd be interested in hearing how the mullards you have compare to my EH's.... how much are you looking to get for them? (email me - add @gmail.com to my username).
How do I tell when/if my amp is overheating? I mean the tubes put off some serious heat, but the tops of the transformers are never more than slightly warm. I never bothered to consider that voltage might be an issue... maybe that's why I couldn't keep light bulbs in my last apartment... Doesn't seem to be a problem in my house though.
I've experimented with different speaker cables, and have come to the conclusion that I can't tell any difference whatsoever on my system. I've tried custom made silver cable, Cat-5 cable, lamp cord, and monster cable. I couldn't tell one bit of difference.
Charles.
I'd be interested in hearing how the mullards you have compare to my EH's.... how much are you looking to get for them? (email me - add @gmail.com to my username).
How do I tell when/if my amp is overheating? I mean the tubes put off some serious heat, but the tops of the transformers are never more than slightly warm. I never bothered to consider that voltage might be an issue... maybe that's why I couldn't keep light bulbs in my last apartment... Doesn't seem to be a problem in my house though.
I've experimented with different speaker cables, and have come to the conclusion that I can't tell any difference whatsoever on my system. I've tried custom made silver cable, Cat-5 cable, lamp cord, and monster cable. I couldn't tell one bit of difference.
Charles.
Tubes good for this kind of bass?
(running, ducking for cover) 😀
An externally hosted image should be here but it was not working when we last tested it.
(running, ducking for cover) 😀
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