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Because of recent debate,I wanted to try a little different approach, when comparing the vintage vs new production reissues.
One of the comments made was,selected NOS tubes which makes sense because matching does make a difference and all the reissues I use are matched quads.
To be honest,I have several quads of British Genelex/GEC KT88 that are matched,but the KT66s I have in NOS gray glass are mostly all matched pairs.
The two pairs you see in the picture have less than 120 hours of time on them..I took them out of the boxes a month ago and played them in my Sargent Rayment amps and the Heath W5ms. The Genelex label on the one was a little sticky from being in the humid boxes but,they are new old stock being I have the boxes labeled Emitron and Genelex and each pair was purchased as NOS pairs in the box.
The reissues have at least 1200 hours on them and they came from Jim McShane almost six years ago and they still test very strong and the two NOS pairs test almost identical with each other as far as transconductance and current goes..
Now the test amp I am using is that Sophia that I redid with FT2 Russian Teflons and Schottkys,and 35uf poly film bypass caps across each of the 180uf electrolytics which I thought were a 100uf until looked closer..Anyway,after I relocated components and fixed the oscillations,it sounds much much better.I gave each set of tubes a 40 minutes warmup.
On first listening tests of hearing Jessica Williams,one of my favorite pianists of all time,the NOS Gens sounded very good with nice crisp detail and had extremely good blend characteristics but what I did notice was,the percussion sounded somewhat forward and I couldn't discern the correct placement of the instruments as well as I could with the reissues at first but,things got a little better with the gray glass Gens after more hours were put on them this weekend.Being the Gray glass are new with little time on them,they improve even more Overall,they are very nice sounding tubes.
The reissues were also a class act.They produced nice focus,detail,and imaged very well and the instrumentals were very correct and in the right places..Both of these tubes mirror each other sonically in so so many ways..They performed very close to each other in just about every way.When one excelled in one area,the reissues performed well in other areas..Overall tho,it is hard to pick a winner.YMMV.
Honest amplification is better than excessive 2nd order distortion anytime.
Follow Ups:
I know your review is for hifi, and soon I will be building a K&K st70 amp with Magnequest iron (5k impedance) to run KT66 or 6Ps3-e.
But in my Marshall JTM45 and my Bluesbreaker, the Gold Lion equal my clear glass GEC with cleans and clipped and almost as sweet as my grey plate. The grey plate has a little more harmonic content to my ears.
My black base Saratov KT66's that I got from Byrd69 sound a lot like my Gold Lions
My Shug Treasures sounded crummy and muddy.
All of them I rebiased For each pair and ran them for a few weeks at a time. Usually they were biased around around 42ma. A few around 44ma.
I would like to burn the treasures in for a looong stretch, so maybe when I build the K&K I can do that.
When I start building some guitar amps commercially, Gold Lions from Jim will be standard. They are phenomenal tubes.
Will you be building an amp based on the original 1961 JTM-45? This I would be very interested in. The best vintage Marshall I played on was an old Bluesbreaker combo. It had KT-66's pushing Celestion Blue alnicos. Crazy overtones. One of the most aggressive sounding combo amp.
Keep us informed!
There are a handful of very good reproductions of both the Bluesbreaker and JTM45 circuit out there (not that I wouldn't build one for someone), but I want to tinker a bit.
I would start with the same Bassman/JTM45 topology and try some different ideas. One thing I am interested in is trying some interstage transformers as the PI and see if there are different saturation characteristics, have adjustable NFB, and maybe use some octals instead of 9 pin in the preamp circuit.
I also want to try out some odd things: maybe a circuit with grid chokes or some plate chokes and see what they do to the sound.
It is hard to come up with something different in a field that has so much history. I love the work George Alessandro has done, and what can one say about Kenny Fischer and HAD that hasn't been said.
As you say in guitar amp it is different and the distortion overdrive is what they look for in those applications..What I have also found is,you can choose the level of distortion you want by the way they test in the new tubes..Higher trans conductance and lower distortion is more for hifi and for guitar you want higher distortion rated tubes or rated different.
I like the Saratov KT66 and that was actually designed by Aspen Pitman of Groove tubes built on his tooling in the Reflektor plant..I like the GL reissues better but they do sound similar as you say.
Honest amplification is better than excessive 2nd order distortion anytime.
Yeah, aspen got it right with those.
The other hard part is so much of biasing for guitar amps is done by ear within a few ma and one can always be suspect of biasing to get similar tone with different sounding tubes.
Best of all, my original pair of Gold Lions from Jim are still going strong in my Bluesbreaker since '08.
Mike, just to anal, what most guitar amps shoot for is harmonics & OD in the pre-amp and input stages. Harmonics in the output stage. OD in the output = very, very loud. Some output bottles have that magic overtones, even at moderate volume levels.
Edits: 03/30/14
In the driver stages? I was wondering because Apsen Pitman and Myles at Groove Tubes were always telling me about distortion ratings and what I need for hifi vs guitar applications.
Honest amplification is better than excessive 2nd order distortion anytime.
Mike, I've found that a clean output stage, not pushed too hard can yield pleasant results. Most vintage 6L6GC Fender amps run around 65% rated max dissipation. Large percentage of the tone is derived from setup of the gain stages and feedback parameters. I use the toughest, cleanest sounding output stage tubes that most hi-fi guys are after. Except for SET amp tubes.Even with this setup, you can really hear the difference between makes, types, and era of output tubes. Every tube has its own characteristics.
Edits: 03/30/14
Marshalls and others based on Marshall's take on the Bassman can have a lot of clipping in the Phase Inverter. It is one of the reasons I LOVE smooth plate Telefunkens in the PI, as well as bp Raytheons and RCA long plate 7025s.
Grey glass mov genalex are such bottles for sure. Swirly, 3d, rich and all other sorts of adjectives.
I have two new quads of reissues and I was going to try a quad and see if they are better than 2007 reissues. I was surprised you didn't like the Treasures..Of course the only ones I heard were the KT88 and 6CA7 and both of those were fantastic.
Honest amplification is better than excessive 2nd order distortion anytime.
Edits: 03/30/14
I was surprised by the treasures also. I like their KT88 too. I am definitely going to break them in further and maybe by another pair to try.
Plus, I was even more surprised because the dragon Shug 66's sound great in Marshals.
Last week, I finished my KT66, NFB, Triode wire PP amp, Instead going to my friend's place, I can compare those GL old and reissue myself in my own system.
Yes, the charcoal bottle KT66 sound slight different, more on romantic side but not better for sure. The reissue is clean and transparent from top to bottom, very balance as well. It is a keeper.
Well stated Walter.Those were my sentiments as well..Now that my reissues have lots of hours on them,they tend to lean on the romantic side as well somewhat.I like the reissues in the sense they are more correct in their sonic nature.Very nice detail,very three dimensional with nice staging..The Gray glass have that as well but on jazz and classical I really like the reissues.
Honest amplification is better than excessive 2nd order distortion anytime.
I no longer have any old production pentodes but have to say that I'm not at all unhappy with new production power tubes.
Dammit Mikey, I have been thinking about 6L6's. Does this tube sound much different than a KT88/6550? I have two single ended pentode amps, a Decware 6V6 Mini Torii and a Triode Corp TRK3488 EL34/6550/KT88 tubes and am thinking about getting one of Denns Had's KT66 Inspire amps.
6L6 has a lot of similarities to the 6550 being the 6550 is like a 6L6 on steroids..Lots of similarities especially in the way they are drive and bias.
Dennis Had built some great linear amps back when he owned Dentron and Ameritron,two companies that he started..I have a Dentron Clipper and an Ameritron AL-80 but the AL-80 I have was a kit from Heathkit called an SB1000.
Dentron folded and then he sold Ameritron to MFJ in Starkville Ms. While Dennis builds some sturdy gear that is well laid out in both Amateur radio and audio,the generic power supply he uses in his audio amps are not very ideal for audio as they are in a ham radio linear amp.They are much too slow and the ESR is out of sight in those computer grade high value electrolytics.
If I were you,I would build a pair of amps and we can help you and you can use choice components..You can get pre cut,pre drilled chassis that are powder coated and then you can install the parts. The single ended amps are pretty simple and I think you would have a good time and good feeling building a couple DIY amps.
Honest amplification is better than excessive 2nd order distortion anytime.
Thanks Mike,I'm OK soldering caps etc. but building an amp...I'm not sure but I will certainly think about it. Meanwhile I have some 6550's coming.
Edits: 03/31/14
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