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69.29.11.17
Constantly & relentlessly trying to improve the 'poinz' PP 6V6 triode connected amp, I have come insanely close to the performance of a $2K in parts PP45 amp. New owner of these 45 amps states best ever heard & quite a few well known 'brand' name amps been auditioned in their audiophile quality system including other 45 designs. The speakers are Tannoy and mate well with PP45s. Anyways, that speaks a lot for the PP 6V6 amp as I heard both- thanks Eric.Auditioning the subject tubes above, I though it would be of interest in the phase inverter position of the 'poinz' design. I been thru a few different 5965 tubes including the well regarded Amperex E180CC 'pinch waist' & the Amperex PQ 7062. The Amperex 6922 is superior to any 5965 family or any simular Amperex, but requires a preamp for full output in this circuit. remember, this circuit is not your circuit & the E1800CC is high quality tube as others reported.
Amperex PQ 6922 'gold pin'
This tube has the large top ring getter with a splash shield (not 'A' frame) manufactured in 1968 (USA). The 'A' frame type did not produce near as good results in this circuit.The Amperex 6922 produces the strongest bass of the three tubes. The bass is reasonably controlled, but not tight nor bloated. The midrange & high frequencies are on the warm side and airy sounding. I also tried Amperex 7308 & they sound identical to the Amperex 6922. As always, the soundstage is wide with plenty of black in-between instruments.
RCA 6FQ7 'clear top'
I am aware a few different versions of these tubes exist. This tube has the grey plates & a round side getter. I also tested the RCA 'clear top' with a square side getter & identical grey plate design. I could not hear any difference in-between the tubes.The RCA 'clear top' bass volume is less than the Amperex 6922 and this is not due to less gain of the 6FQ7. The bass is tightly controlled without any congestion & still ample for all the program material I use in my audio system. Perhaps some older rock music might be better with the Amperex 6922 response, however it would depend upon the speakers. The midrange and the high frequencies have more detail and are slightly more forward than the Amperex 6922. No doubt these tubes are brighter in the upper mids & high frequencies than the Amperex 6922. Others have stated too bright, but I find some minor congestion or perhaps better described as a minor compressed sound in the upper mids & highs.
RCA 6CQ7 'shielded'
This tube has the non-shiney ribbed black plates & small square top getter. I also listened to a pair with identical plates & larger horseshoe type getter. Both tubes sound identical. The bass is the about same as the RCA 6FQ7 'clear top', perhaps just slightly stronger. The midrange is as detailed as the RCA 6FQ7, but more open without that slightly compressed sound. Again, is the bright sonics of the 'clear top' reported by others actually that slightly congested sonics as I hear the tubes?Anyways, the RCA 6CG7 are clearly the winner in my circuit. I would have no issues paying $40 a pair for NOS RCA black plate & I will purchase four more of the RCA 6CG7 as these tubes are getting more difficult to find.
Keep in mind, the most confusing issues of reporting sonics are tubes perform differently in different circuits. Your audition may differ than the results in my amps. A special thanks to others for recommending these RCA black plate tubes to me.
Follow Ups:
I am glad you found the 6cg7 a worthwhile tube change. Given what you heard and what I have found with them I might suggest you try a different brand. As AnandR mentioned the Raytheon is a great tube (if you find a source be nice and share please)...the best I have heard so far. But then I have not heard the CBS or TungSol yet. Slyvania's are rather good and one of the easier ones to find. I suggest you try a pair of them and see what you think. They have black plates but a chrome divider. It might help to ground the divider too. It might also be worth the time to readjust the operating conditions a bit (the 6cg7 might do better with a higher plate voltage and/or more current as the 6922 can be run at rather low voltages and still do well). I suggest this because you seem to indicate the 6cg7 is a more forward sounding tube than the 6922. IMHO the 6cg7 should sound more delicate (a slight silvery sheen to brushed cymbals) and less steely than a 6922 in the highs. But that's just my experiences and of course the circuit involved dictates a lot. If it matters I run them in a cascode as well as a split load invertor.Either way I am glad you liked them. But I do think you can do even better with a different brand and maybe a little tweaking (basically run at 6sn7 operating points). Nice write up and good luck. I might cobble up one of those amps soon myself and when the time comes I'd appreciate hearing your thoughts on possible circuit changes and improvments. A friend just picked up some Lowthers and I am thinking a triode strapped PP 6V6 amp might be magic compared to the PPP 6L6 amp he is now using.
Hi fellas,I got the Raytheons from the tube dealer with the moniker: Tubes42. He's an excellent E-bay dealer. Very reliable and fast shipping. From Washington state I think. On my preamp, at 10mA, their plate voltages matched to within 2-3 volts. That's pretty close matching I think. I am using Gary Pimm's Constant Current source.
But alas, that's an old story now. My preamp has been retrofitted for 2C51/5670/WE396a's, and the sound is even better! (And No, I am not selling my stash of 6CG7's. They will stay for another project someday).
I found a set of NOS Raytheon 6CG7 shielded black plate at AES, but they are the last pair. I also found a pair of NOS Sylvania black plate chrome shielded. I will report back the sonics of these tubes when they arrive.I find the RCA black plate excellent. If the Raytheon or Sylvania outperform the RCA in my circuit, it will be interesting. This 'poinz' design amp is very good. The design I have uses top quality components such as Mills resistors, oil caps & a LCLC power supply with an additional LC section for the 6CG7.
all circuits, not to mention all ears, are a little different.
FYI, both Ei and Electro-Harmonix have a 6CG7 out. Both are ~$12.
I have not tried them, but I like both companies' tubes generally.
the Ei sounds decent per Jim McShane. I also tend to like the Ei small tubes and the EH output tubes. Nice to be able to buy reasonable priced good sounding new tubes again isn't it
you folks are paying *WAY* too much for tubes. From the local Audio & Video shop: 7 sleeves of RCA cleartops for $2.85 per tube. Same for a few sleeves of GE's.This does not count all the heartbreak involved when a TV shop guy tells me he threw out his entire collection in the past year, and then rattles off the high points of what he paid for some of them and how *NOBODY* wanted that stuff so out it went. "I would have given it to you if you had asked". From what is likely 100k tubes, I am sure there would have been a few 6CG7's of every sort and description.
they are not doing anybody any good in the landfills. If they get dumped at sea, some might wash up on shore....
cheers,
Fred
then I place my order with you. I'll take a quad of NOS RCA 6CG7 black plate. Is that still $2.85 per tube? Or just make it $8 per tube.
sorry, not a dealer. I do recommend you do your own research/shopping.
cheers,
Fred
As stated in tubes section, only RCA 6CG7 black plate with shield I found in the USA was at Radio Daze.
There cannot be a single source of that valve. I'll bet I cna turn up some in less than a week. I'll expand that to include you if you shop in the right stores. $3/tube will be an expensive undertaking if you have to buy a comlete stock.
cheers,
Fred
Tube dealers that do not have NOS RCA 6CG7 black plate shielded-AES
Radio Electric Supply
Tucker
RF Parts
ESRC
N9TEW
Tube World
Vacuum Tubes, IncSND does have them at $25 each, not $3 per your post that is indicating your proposed value of these rare tubes. Radio Daze does have a few as I previously mentioned at about $17 each plus shipping.
Some other less known tube dealers do not sort thru tubes for specific parts.
you should have said, "I have not yet found a dealer with that sort of pricing".they are out there. look harder, and you shall find. I have been looking, and I have been finding. Shall I post my next acquisition in an itemized fashion?
cheers,
Fred
.
When I know, it will be too late for anybody else to acquire them. I will have already done so, and since I am only looking to add to my stock, the trail will end there. I am not going to be a dealer. My friends who get shown to the stock pile might have a shot at them...Look around, there are *MANY* sources yet to be discovered. Many are about to cease going to the trouble of being tube sources, and will end with a trip to the dumpster.
get offa yo backside and look around fer yourself. It is satisfying!
cheers,
Fred
...let alone piling up on cheap eBay buys and culling them out for the "best". It still works out "cheap".Did you get my email reply after the audio meeting? If not, check your junk mail folder just in case!
When I know, it will be too late for anybody else to acquire them. I will have already done so, and since I am only looking to add to my stock, the trail will end there. I am not going to be a dealer. My friends who get shown to the stock pile might...Look around, there are *MANY* sources yet to be discovered. Many are about to cease going to the trouble of being tube sources, and will end with a trip to the dumpster.
get offa yo backside and look around fer yourself. It is satisfying!
cheers,
Fred
Excellent review Jimmy. And right you are about the same tube performing differently in different circuits. I for one like the Raytheon 6CG7. Its not as 'bright' on the top end as the RCA type, bass is a little looser and midrange is more open. Soundstage is holographic. This was in a single ended parafeed CCS based headphone/preamplifier.
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