- #171 [ptsang], 07-03-16 17:18Matthew, that's a good idea. I will certainly ask KC to arrange (if possible) when the time comes. Still very much want to read the review by Positive Feedback, it makes me itchy.
- #172 [ptsang], 07-03-19 17:11Timtube hing and F2ayeung hing, do you know is it possible to replace the 6072 tubes with 12ay7 in the Kondo M77 pre.
- #173 [F2aYeung], 07-03-19 18:01ptsang hing,
In fact I am using 12AY7 in my M7 Tube with no perceivable drawbacks.
I believe M77 runs the 6072s in parallel so getting 4 6072 with a perfectly matched pair of triodes inside the tube for the line stage is quite important. Like matching a pair of 300B in a parallel SETA. -
- #174 [ptsang], 07-03-19 22:17F2aYeung hing, why you don't use 6072, is it because 12ay7 better sounding than 6072. I never use any 12ay7 before, what brand you recommand and is it older the tube the better, assuming the 2 triodes inside the tube are matched.In the M77, I use 4 GE6072 for the line, a pair made in 1959-1960, the other pair made in 1956. They sound great, but still want to try other sub for a different sound.
- #175 [F2aYeung], 07-03-19 23:01ptsang hing,
I use 12AY7 only because of the price. A few years ago I bought a few of them from O si Luk in Mongkok at peanut price. They were unpluged from old old computers and are of the slanting square halo type. I compared them to some costly 6072 and could not notice any difference.
Anyway I found changing the 6X4 makes more difference than swapping 6072. - #176 [ptsang], 07-03-19 23:15F2a hing, you are right, among the many 6x4 in hand, I found the 50's Genalex U707 sounds best in nearly all parameters, but it takes weeks to burn-in, before it's completely done, it sounds raw and bright in the mid. Don't know if you have the same experience.
- #177 [timtube], 07-03-19 23:20Yes, the rectifier is more important than other tubes as a general rule.
12AY7 is practicially the same as 6072 and there should be no problem in cross-substitution.
But the problem with BOTH 6072 and 12AY7 is that the choice of manufacturers are extremely limited with nothing from outside USA.
I always recommend people to try Brimar 13D3/CV4068 in AN to replace 6072. But I never tried this myself (as I never own any AN pre-amp) nor did anyone ever listen to me.
In theory, it should work. And even if it draws more filament current from the power supply, it will not produce any harm or damage to the pre-amp itself. Just make sure the power transformer does not heat up compare to using 6072.
13D3 is essentially a ECC32 in a miniture bottle. And I understand ECC32 is a favourite with AN UK. - #178 [timtube], 07-03-19 23:21Genalex U707 is wonderful. But I found early GEC CV4005 has a large sound stage by comparison.
- #179 [timtube], 07-03-19 23:22Typo. "large" should be "larger".
- #180 [F2aYeung], 07-03-20 07:20>But I never tried this myself (as I never own any AN pre-amp) nor did anyone ever listen to me.
I check the spec. It's indeed quite close to 6072. Do you have any available for trial?
I hope it does not sound ECC32 which sounds muddy and sluggish to my tin ears. - #181 [timtube], 07-03-20 14:01Brimar 13D3 is very popular in Hong Kong as it is one of the very very few tubes that work properly to replace RFT 12AU7 in early CAT SL1 pre-amp (Most 12AU7 will not work OK in that pre-amp).
I think Choice has a large supply but I should also be able to dig up some for you to try. - #182 [ptsang], 07-03-20 22:04timtube hing, how to distinguish early and later GEC CV4005 structural-wise, and what's the difference between GEC CV4005 and U707, are they differed only by the codings, both made in the same factory in the 50's by GEC.
Would like to try the 12ay7 first and then the CV4068. - #183 [timtube], 07-03-21 14:38Early GEC CV4005 has square getter.
6X4W=CV4005=U707 is the miltary version of 6X4. most of them has double getter support and some have triple mica.
6X4=CV493=U78 usually only has single getter support.
In general, you will find 6X4W to be more hi-fi sounding wide wider frequency range; while 6X4 tends to sound more laid back and warm. - #184 [timtube], 07-03-21 14:39Would like to try the 12ay7 first and then the CV4068
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I think it is unlikely you will find any improvement of 12AY7 over 6072. - #185 [ptsang], 07-03-22 19:50timtube hing, never seen one U707 with triple mica (can't imagine how it sounds), must be early 50's or even earlier.Will try early 50's 12ay7, the constructions of this type of y7 are so different from the 60's 6072, even the 50's 6072 sound different from later 6072,can't resist the temptation to try it in the M77.This naughty old guy can rest if they don't sound asgood as the 6072.
- #186 [F2aYeung], 07-03-22 23:01timtube,
I just notice that PQ is also using 13D3 for his 'Ongaku' input stage.
To experienced tube enthusiasts, Peter’s choice of the Brimar NOS CV4068 at the input stage is to be applauded. Manufactured only by Brimar, the CV4068 is renowned for its delicate and extended top-end, as well as a substantial lower midrange. Driver stage is assigned to an original Telefunken diamond NOS 6463 double triode..... - #187 [ptsang], 07-03-23 16:57F2a and tim ,I'll try all 6072 subs in the preamp, dare not to try in the Ongaku, it could be devastating if not the recommanded tube type is used, though there is a cap between the first and 2nd stage in the Ongaku.
- #188 [MatthewC], 07-03-23 23:34Peter,
While this may sound utterly evil, but let's say, the sub causes problem, and it happened to your M77, your Gakuoh is out of action, as well as you Ongaku missing the pre. OTOH, if it causes you problem in the Ongaku, you have you chance to get that NFB switch installed :-) - #189 [JCR33], 07-03-24 06:14MatthewC,
TY = Thank You! - #190 [ptsang], 07-03-24 10:35Mat, use a wrong/bad tube in a preamp(not transformer coupled) will usually trash the tube(except the rectifier tube), the pre will remain intact, but in the case of power amp, the result could be disasterous especially the Ongaku running at 1000V. F2a and tim, correct me if I'm wrong.
JCR, I can see that you finally try the fat bottle CV378,it has a very different sound from the metal base Philips GZ34. People used to say tube rolling is only a matter of personal taste, in some cases, it can really raise the performance of your gear to a level you can't imagine.Painly speaker, the stock tubes will render the Ongaku a bit dull upon long time listening. - 下一頁 (9.5 of 39)
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