dubadub,
And everyone else . . .
if you can read this all the way to the end, you may be surprised.
When you point your nose 3 degrees starboard . . .
For any music performer that is in the center of L and R, a very curious thing happens.
A Comb Filter, causes cancellations of some frequencies, because the Left ear's distance to the Left speaker, and the Right ear's distance to the right ear are different at some frequencies. Thus, we discover and hear that Comb Filter effect on the sound.
I will take a 0.5dB un-balanced gain error any day, versus hearing the Comb Filter effect.
You may ask how I know?
After I lost the hearing in one ear, I started hearing the Comb Filter effect in situations that I had never heard that before.
Without both ears, and the brains processing Power-of-Two, the brain can not process out the Comb Filter effect.
Stereo hearing with 2 ears, and Stereo seeing with 2 eyes.
Only 1 ear; only 1 eye, a lot of brain processing power goes away (not enough input to process).
Although I lost one ear, I still have both eyes.
But, sometimes I hear things, and I hear more clarity, that I never heard before on some of my familiar recordings, versus when I had two ears:
At my computer, I often only play the Left channel, using a self inverting 6V6 push pull mono-block tube amp, and a single speaker (one Usher S-520).
No matter the recording, pan pot or not, spread omni, multi mike, mid-side mike, or any other microphone technique . . .
There is absolutely No Acoustic Comb Filter Effect coming from the Single loudspeaker.
I learned a lot when I lost one ear.
$0.03
And everyone else . . .
if you can read this all the way to the end, you may be surprised.
When you point your nose 3 degrees starboard . . .
For any music performer that is in the center of L and R, a very curious thing happens.
A Comb Filter, causes cancellations of some frequencies, because the Left ear's distance to the Left speaker, and the Right ear's distance to the right ear are different at some frequencies. Thus, we discover and hear that Comb Filter effect on the sound.
I will take a 0.5dB un-balanced gain error any day, versus hearing the Comb Filter effect.
You may ask how I know?
After I lost the hearing in one ear, I started hearing the Comb Filter effect in situations that I had never heard that before.
Without both ears, and the brains processing Power-of-Two, the brain can not process out the Comb Filter effect.
Stereo hearing with 2 ears, and Stereo seeing with 2 eyes.
Only 1 ear; only 1 eye, a lot of brain processing power goes away (not enough input to process).
Although I lost one ear, I still have both eyes.
But, sometimes I hear things, and I hear more clarity, that I never heard before on some of my familiar recordings, versus when I had two ears:
At my computer, I often only play the Left channel, using a self inverting 6V6 push pull mono-block tube amp, and a single speaker (one Usher S-520).
No matter the recording, pan pot or not, spread omni, multi mike, mid-side mike, or any other microphone technique . . .
There is absolutely No Acoustic Comb Filter Effect coming from the Single loudspeaker.
I learned a lot when I lost one ear.
$0.03
A bit of a mountain out of a mole hill .... Like 6A3sUMMER I shop at Eurotubes, though I can't drive over. I just looked at their site to confirm my thoughts regarding prices. Using 6L6GCs as an example:
1 tube $28.50
matched pair $57.00
matched quad $114.00
Given the cost per tube is the same, why not buy a matched quad?
It's my understanding that Eurotubes checks every tube so perhaps their pricing structure is different than others.
1 tube $28.50
matched pair $57.00
matched quad $114.00
Given the cost per tube is the same, why not buy a matched quad?
It's my understanding that Eurotubes checks every tube so perhaps their pricing structure is different than others.
The most expensive matched tubes are NOS. It is easier to match current production tubes, plenty of those available for a dealer, but when you want to match two or four PL519 or something like that, the prices go through the roof.
- One NOS PL519 ~ £30.00
- Matched pair ~ £200.00
- Matched quad: £350~£455
You can buy new production EL509 ( sort of without top connector and with octal base ) for $256 for a matched quad
eurotubes EL509
eurotubes EL509
prairieboy,
Yes . . . Eurotubes extensively re-tests every tube they get from the JJ factory in Slovakia.
Tests include tube specifications such as classic tube operating condition(s). And they also test for noise, leakage current, etc.
Their accurate tube matching has allowed me to build amplifiers that would need additional circuit(s) if the match was not that good.
If I am thinking about building a new amplifier circuit (new to me, that I have not tried before),
I first ask the question, is there a JJ tube that I can use?
Yes . . . Eurotubes extensively re-tests every tube they get from the JJ factory in Slovakia.
Tests include tube specifications such as classic tube operating condition(s). And they also test for noise, leakage current, etc.
Their accurate tube matching has allowed me to build amplifiers that would need additional circuit(s) if the match was not that good.
If I am thinking about building a new amplifier circuit (new to me, that I have not tried before),
I first ask the question, is there a JJ tube that I can use?
I'm curious how well modern matching of power pentodes would translate to triode-wired operation. I've heard the KT-77 has good triode curves and was thinking about trying that out eventually but I'm wondering how good the odds are of getting an OK match in triode mode for something like that.
Charles G,
I almost always use my JJ Beam Power tubes in Triode Wired mode.
6L6GC, 5881, KT66, and KT77 for example.
They work good for me.
A few times I have used the JJ Beam Power tubes in Ultra Linear, that works good for me too.
I mostly do push pull and balanced modes; but I also used them all for single ended (Triode Wired, and a few times in Ultra Linear).
They worked good there too.
I have not done any DHTs for either single ended, or for push pull, for a very long time.
Remember, I build low power mono-blocks, and I run the tubes at less than their maximum dissipation.
I drive relatively large impedance primary windings, versus the Triode Wired plate impedance.
I no longer use Schade NFB, output plate to driver cathode NFB, output secondary to cathode NFB, or global NFB.
Most of my amplifiers do not use local NFB either; the exceptions are:
Balanced with cathodes tied together to a single un-bypassed self bias resistor; and the ocassional Ultra Liner mode.
Well . . . I think Triode Wired is the shortest two tube elements NFB loop known to man.
Your Mileage May Vary.
Have Fun!
I almost always use my JJ Beam Power tubes in Triode Wired mode.
6L6GC, 5881, KT66, and KT77 for example.
They work good for me.
A few times I have used the JJ Beam Power tubes in Ultra Linear, that works good for me too.
I mostly do push pull and balanced modes; but I also used them all for single ended (Triode Wired, and a few times in Ultra Linear).
They worked good there too.
I have not done any DHTs for either single ended, or for push pull, for a very long time.
Remember, I build low power mono-blocks, and I run the tubes at less than their maximum dissipation.
I drive relatively large impedance primary windings, versus the Triode Wired plate impedance.
I no longer use Schade NFB, output plate to driver cathode NFB, output secondary to cathode NFB, or global NFB.
Most of my amplifiers do not use local NFB either; the exceptions are:
Balanced with cathodes tied together to a single un-bypassed self bias resistor; and the ocassional Ultra Liner mode.
Well . . . I think Triode Wired is the shortest two tube elements NFB loop known to man.
Your Mileage May Vary.
Have Fun!
Last edited:
Thank you, but not for me. I only buy NOS tubes, usually from e-bay. Nothing wrong with JJ or any other tube manufacturer, just not for me. Part of the fun is buying an obscure lot of TV/Radio tubes on the cheap and finding some gems there.
And about the EL509 in particular, I prefer the PL* ones with 300mA heater. A quad EL509 will need 10A (8 for the JJ) for the heaters.