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Post by mossback on Sept 2, 2008 14:32:00 GMT 7
On a whim I connected very low power DIY amp to my Harbeth. Wow, it sounds not bad in my medium sized room. All this time I thought PP EL84/6V6 amps were absolutely the lowest one could go power wise.
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odaey
Junior Member
Posts: 62
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Post by odaey on Sept 2, 2008 15:49:14 GMT 7
Hi Dan,
what tubes does the DIY amp use? (I'm assuming that this is a tube amp),
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Post by mossback on Sept 2, 2008 19:07:34 GMT 7
SS rectification, RCA 6SN7, Western Electric 421A dual triode. I used old 5K Fisher output transformers. The 421A’s are PP at around 8w, I just copy what others have done as my knowledge is not enough to figure this out on my own...Dan
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Post by splendor on Sept 3, 2008 12:59:36 GMT 7
Dan, my TS34.1 single ended had a decent sound on the LS3/5a.
I read that the 15ohmers LS sound great on 300Bs. If the 15 ohmers have more bass bloat or hump than the 11 ohmers (what would Rodny say?), it may well sound "right" on an otherwise lean sounding amp. Ferdy's Conquerors of the past would have been decent on the Stirlings! As I recall, it sounded "thin" or "light" on the Spendor 1/2E, but the clarity can make one think he's happy over it until it gets lighter and lighter on the ears "feeling." Then, it makes one wanna move up again to higher watts. Tricky business, this listening!
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Post by mossback on Sept 3, 2008 16:43:16 GMT 7
If I remember correctly it was your 9 watt SE EL34 amps through the Dynaco A25? Nice little amps my friend. The 421A is not a perfect match for the LS but it works surprisingly well. Soon I will finish a scratch build of a very special ST-35 clone. It’s all new including one off MagneQuest/Peerless nickel output transformers. I have very high expectations for this little guy! It’s my hope that it can be an Eico-Pilot killer?
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odaey
Junior Member
Posts: 62
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Post by odaey on Sept 3, 2008 19:38:03 GMT 7
quite embarrasing but i know nothing about the 421a's. My experience with low power amps for the Ls3/5a's are with 300B and 2A3. My preference is with the 2A3 driving 15 ohmers. It seems to have more than the 3 watts it claims,dynamic yet smooth. Of course SPL's is highly dependent on source output (mostly CD's recorded with highish level). The 2A3 tubes seems to control better the rather soft/bloomy bass (or Bloat as james would say) of the 15 ohm Ls.
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Post by splendor on Sept 4, 2008 3:17:01 GMT 7
The "lesser" power does it some good. With good recorded material, it's all good I think.
Dan, the el34s seem to cater well in so far as tonality on the A25s. Expressive enough for soft gentle mellow listening. I remember you gave me an article from vacuum tube valley that rates these A25s highly. Accordingly, the first speaker to give good imaging, and sounds twice their price.
Dan, the ampex is sounding very good on my Phase Tech. The hardness you n oticed is gone. That was the output but it's now singing. I should hear what's going on with yours.
Have you tried it yet, and oh what happened to your Stromberg ASP 422? I didn't hear you say anything about that yet. Mine is singing again after changing an inverter resistor on both channels. I've lived with this amp for a long while and can't seem to go without them, both the ASP 422 and the AC 220 with 6V6s on them.
My Winged C el34s are now in place. The sound is romantic in comparison to the RFTs.
Good luck on your new toy. Do you have the complete pair now of the Black 12? Regards.
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Post by mossback on Sept 4, 2008 22:22:11 GMT 7
Well if you know about the beautiful 2A3 then you know the Western Electric 421A because it is like two 2A3’s in one envelope. So I use one WE 421A vacuum tube for PP SET at ~8 watts. It was James who got me interested in the double triode one-envelope type after hearing his Stromberg Carlson ASP 422 amps. My ASP 422 needs a rebuilt. OK good, the defective Ampex output caused that hardness. I’m glad you are pleased with it now. My Ampex started to smoke! I got red plates on one output tube and a burning smell. Parts are on order for it now. I will send some K40 oils with Greg for yours James. It looks as though Greg will not be able to bring my Black 12’s with him as he is only having a short layover in HK. I guess I’ll just have to bite the bullet and have them shipped over. Ouch$$$!!!!
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Post by splendor on Sept 5, 2008 11:32:06 GMT 7
Sorry to hear about the ampex and SC. Buying old stuff is always a big gamble, but so is life in everything we do. Rod always tells me there's nothing he can't repair with vintage stuff, and that to me is quite an assurance. Good for you Dan because you're a diy'er.
Thanks for those k40s. Are they signal cops, those russian caps?
I need to change two resistors, the 5 watts because apparently the ones in the ampex now are under rated at 270 ohms resistance. 400 to 500 ohms at least. Rod told me to stepdown my ac to 100volts, and I did. The tubes are no longer turning a bit redder.
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