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PostPosted: 09 Jun 2010, 23:02 
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Joined: 04 Jun 2008, 20:59
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Location: Arizona, USA
Hi Everyone, This is an open ended thread on how tubes sound or act in our projects. If you post please tell us what equipment they were used in so we can make some sense of it all. No bashing please, but differing opinions are certainly expected and welcome. As they say in the TV adds, your results may be different. As you might expect I have tried a number of tubes in the projects I design and build not all are good. I'll start out with a few types of power tubes used in my OddBlocks. All are new production unless noted otherwise.

Gold Lion KT88 - good all around sound, nice midrange and high freq presentation, clean sound, good sound stage and imaging, good detail, generally hard to fault

EH KT88, won't stay balanced in the OBs. Probably OK in other amps

JJ KT88 - similar to the Gold Lions, not as detailed

JJ Blue Glass KT88 - Better bottom end than the Gold Lions, rather similar in sound to the GL KT88. A clean but polite sound. My personal favorite

JJ KT77 - Less bottom end than most, very clean mid and high presentation. A great tube for female vocals and stringed instruments.

JJ 6L6GC - powerful bottom end, too crisp in the mids and high for my liking. Seems to overload better than most. OK if you like rock music

Sovtek KT88 - nothing special in any way. I would pass on these.

Sovtek 6L6WXT+ - A more powerful 6L6GC, more bottom end than the standard ones, IMHO a rather gritty sound. I would pass on these as well

Sino EL156 - A big tube with a big sound. Very powerful bottom end, nearly too much (if possible), crisp sound, good detail and presentation. A good tube for rock music. A bit too raw for me.

Russian GU50 - powerful but not as pleasant as most of the more common tubes. Not high on my list

Russian 832 - A funky tube, IMHO better suited for its original purpose in transmitters. In push-pull parallel was a marginal performer in all ways. Cute, but not really in the league with the other guys.

EH EL84 - Good all around tube, nice balance, sound stage and imaging. Second best sound in the Poddwatts.

Sovtek EL84 - Also a good tube, measured slightly lower distortion that most EL84s in my amps. Surprisingly the best overall sound in the PoddWatts. My number one pick there.

Mullard EL84 - Mellow sound, easy to listen to, IMHO not as detailed as the EH version

JJ EL84 - Ok but not special in any way.

Just my two cents, jump in everyone. What are your experiences.

Good listening
Bruce

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PostPosted: 10 Jun 2010, 02:28 
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Joined: 24 Feb 2009, 03:24
Posts: 562
Location: USA
6P3S-E russian/similar to 6L6/ - powerful bass, detail, but little bit scream sound....for rock music IMO.

Now I make ampl. 6P3S /it's different 6P3S-E/ and will post some results later, because I driled.....
my main transformer! I will try and with EL34 Mullard.

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Projects: OTL 6AS7 Gen, Electric, SEs 2A3 RCA, 300B JJ, 6S4S, 4P1L, EL11 Telefunken, 6AS7 RCA, 6S33S, 6S41S, 6S19P, PP 6005 Gen. Ellectric , headphone ampl. OTL Loftin White 6AS7 RCA....SE E84L& E80CC Siemens&Tel-n.
http://azazello-sound.blogspot.com/


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PostPosted: 10 Jun 2010, 06:28 
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Location: Chilliwack, BC
BEL India EL84 - Very similar to the Mullard sound. Tight lows, clear mids, neutral highs. Creamy smooth OD if used as a guitar tube. Most of these were made on Mullard equipment, unlike the pre tubes that were made on Philips.

Ruby EL34 - There are good lots, there are bad lots. Good lots are really authoritive bass when used in an ST-70 circuit, detailed mids and clean highs.

Winged =C= Svetlana EL34 - THE tube when tested in an ST-70 style circuit. Quiet, clean, detailed, punchy bottom.

JJ KT88 - Great highs, neutral mids. Painfully neutral-to-the-point-of-flat bass as listened to in an Audio Research 76D.

Cheers!

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* Ratings are for transistors - tubes have guidelines*
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PostPosted: 10 Jun 2010, 08:05 
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Joined: 12 Jun 2009, 15:43
Posts: 87
Location: College Station, Texas
Hi. I haven't tried much experimentation myself with comparing different tube brands, but I find it very interesting to learn about the substantial differences in sound that they produce. Especially, I am wondering if the underlying reasons for the differences are understood? Do the different tonal qualities correlate in a known way with measurable differences in the tube parameters, I wonder?

Just curious,
Chris


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PostPosted: 10 Jun 2010, 08:33 
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Joined: 14 Feb 2010, 13:13
Posts: 715
Location: Lisbon, Portugal
As for driver tubes I have tried these:

* JJ Tesla ECC83S - Lots of gain, specially on highs, easy to saturate with a CD Player. I´m confident that it´s a good match with a turntable.

* Philips JAN 5751 - Less gain, all round frequency response, more balanced. Offers a very warm sound.

I wonder if there are any EL34´s comparisons out here?

Cheers,
Miguel


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PostPosted: 10 Jun 2010, 09:15 
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Joined: 04 Oct 2008, 11:29
Posts: 375
Location: Chillicothe, Ohio
cnpope wrote:
Hi. I haven't tried much experimentation myself with comparing different tube brands, but I find it very interesting to learn about the substantial differences in sound that they produce. Especially, I am wondering if the underlying reasons for the differences are understood? Do the different tonal qualities correlate in a known way with measurable differences in the tube parameters, I wonder?

There are hardliners who insist that there are dramatic differences in the sound of a system when tubes are swapped. Then there are those who mock them for even suggesting such a thing by insisting that such a device cannot have a "sound".

I, for one, know that in my systems there are audible differences made by swapping tubes. That being said, I'm inclined to believe that it can have much to do with the circuitry being used. In a vintage HH Scott 299 rebuilt with totally non-boutique parts, GE 7189s sounded painfully harsh. With no other changes, swapping to Sovtek EL84s smoothed out the sound immensely, but at the cost of much detail and spaciousness in the soundstage. Someone not looking for that open, wide soundstage may think the Sovteks sounded better. Instead, I thought it was a trade off of sorts, as is usually the case. In another 299 rebuilt with some boutique parts, the GEs are phenomenal, with no harshness. Likewise with Philips ECG 7189s. The Sovteks are very unpleasant, with muddled up soundstage and poor imaging.

I do not claim to have the knowledge to explain why these devices sound different. Some claim it's psycho-acoustics. Whatever the reason, I'm glad it's there, whether it's my mind playing tricks or it's real.

Cheers,
Greg


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PostPosted: 10 Jun 2010, 10:38 
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Joined: 26 May 2009, 18:51
Posts: 130
Location: Lilburn, Georgia USA
Hi everyone, Has anybody had a chance to try the KT120 tubes yet?


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PostPosted: 10 Jun 2010, 13:24 
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Joined: 05 Jan 2010, 21:16
Posts: 680
Location: Las Vegas Nevada USA
gofar99 wrote:
EH KT88, won't stay balanced in the OBs. Probably OK in other amps

My EH KT88 tubes have stayed perfectly balanced now for 2 weeks - less than 1mA deviation. There is definitely NOT a problem. I ordered mine from Tube Depot in January. I think a bad batch or badly mismatched tubes was the cause of that problem, not the design of the tube or the oddwatt.

They sound great to me but I have nothing to compare them with.

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PostPosted: 10 Jun 2010, 15:58 
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Location: Arizona, USA
Hi Everyone, Great start. I will have a set of KT120s Tuesday, so I'll give them a run ASAP. That was good news on the EH KT88s. They may suffer from the same things other newly restarted tubes have experienced. That is inconsistent quality at start up or from lot to lot.

One question was of interest.... do tubes that sound different test different. Great question. After testing on the bench many tube types in my projects including running them on a distortion analyzer and on a spectrum analyzer. The answer is sometimes. Overal frequency response is usually quite close up to about 40K, then some fall off sharper than others. Interelectrode capacitance is likely the key player. In some tube types I find more distortion in the sub 100 HZ range than other types (can be as much as 5X). I can't measure the S/N below -90 accurately, but it seems that some tubes are not as quiet as others. Gain is sometimes different between different brands of the sames tube (as much as 10%). Bias points can be off a bit as well. So yes some things that we hear can be measured. Many don't lend themselves to measurments.

Next time I'll post some thoughts on driver tubes.

Good listening
Bruce

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PostPosted: 10 Jun 2010, 17:07 
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Joined: 06 Jun 2008, 18:23
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Location: Australia
I've been staying with KT88s lately in SE UL and Triode builds. I discovered to change the sound of the KT88 just up the idle current. From 62mA to 92 mA makes the tubes perform much better. Lots of bass (though not deeper bass) good control of the bass (though not in the SS league). Problem is before I could tube roll 6 or 8 different tubes now with the higher current I'm restricted to a few. Mids are clean and sweet and treble balanced and not over done. Siblance is perfectly controlled and almost non-existant on most recordindg.

After living with this change for a few weeks and getting some excellent comments from others, now I could never go back. There is so much these big pentodes have to offer and you will never see it if not pushed. My current amp is UL only at this point.

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