[exdmd]

Not my experience with the 12B4A today unfortunately. Matched pair of GE's from the 60's sonically inferior to the RCA 1626 in my system. May have received bad tubes if so first time from my usual source. Still using a 1963 Telefunken ECC801S for input. Had to put the RCA 1626 back in to get the magic back.

 

[cute]

I thought I sold you a pair of Tung Sol 1626, maybe someone else?

 

[exdmd]

You did one died had to use my backup pair which did not sound as good as RCA 1626. Just using the best RCA 1626 I can source.

Ordered a second matched pair 12B4A from a different supplier to try again. Should have by the weekend.

 

[ampsandsound]

12B4A/5755 is a SOLID combo.

 

[exdmd]

Can same convertor for ECC801S > 12SL7GT be used for 5755 or is this convertor necessary?

 

[cute]

You need the converter you have linked, or similar.

 

[exdmd]

Thanks @cute what I thought. I'll try the 12B4A/5755 to see how it compares to my favorite ECC801S/1626 in my rig. Takes a couple weeks to get the converter.

 

[buke9]

I never get heads up on this thread and it says I’m sub’ed . Love the talk of the 12B4A’s and not too expensive to try out. Will wait to hear more impressions of the different tubes as I’m waiting for credit card bills to come in from 10 days in Greece so it will be a bit (I recommend a visit there as the country side and food and people are so lovely 25th anniversary epic trip). I’ll sneak in a adapter or so in the next couple of weeks and then decide on a tube to buy. Still really like the Raytheon 5755 as input.

 

[exdmd]

OK second try, this time with a matched pair of CBS branded/Hytron 12B4A's today. Very forward midrange with a hard edge to vocals that drilled a hole in my head. No depth to sound stage and lack of air around voices and instruments. Sounded like timbres were off. When I can't enjoy Diana Krall on Tidal there is a problem. The reason you invest in a "Holy Grail" Telefunken ECC801S input tube is to get the natural midrange, sound stage and air and the 12B4A's do not play nice with the Telefunken, took away all the great sound I am used to. Not sure where the problem lies but with my input tube, DAC+ and HD800S phones 12B4A's are a no go. After cool down I put the RCA 1626's back in. I think I am done with rolling power tubes in my Kenzie and am sticking to 1626's. At least the experiment was inexpensive. YMMV.

Surely my experience is not unique. Based on my trial I don't think you can count on the 12B4A as a direct replacement for the 1626. @ampsandsound can you duplicate my results at your shop?

 

[exdmd]

Discovered that the 12B4A do not like being driven by the Telefunken ECC801S for some unknown reason. Substituting a good 12SL7GT corrects most of the sound quality problems I encountered. However in my rig I went back to the 1626 and Telefunken as that combination provides the best sound I have heard from my Kenzie. Have not tried the 12B4A/5755 yet, still waiting for convertor from HK.

 

[EDWARIS]

I see here new Agartha 2.0? any comments, what is new, what is better?

 

[ampsandsound]

8,32,300 ohm 1/4” jacks.
Revised transformers.
Revised power supply.
Blessed by Elves. Keebler style.

 

[exdmd]

Finally tried the 12B4A/5755 with two different brands of matched 12B4A's and a very good 1950's Western Electric clear top 5755/420A using the convertor. First thing I noticed was soft bass: bass was there but sounded soft with no punch or heft. This was with either matched pair. I only had the one 5755 to try. Mids and treble were fine and the sound stage with GE tubes had good depth. Took the 12B4A's out put the 1626 back in and bass returned to normal. In my rig the 5755 sounded no better than a good 12SL7GT so the 12B4A/5755 is not for everyone. It is not that expensive to try out and your experience may be different than mine. Seems system dependent.

I lucked into a particularly nice matched pair of RCA 1626 from 1943 that came in an RCA box, not the generic wartime beige boxes you normally see. These are the best sounding RCA 1626 I have ever heard and are very close to Tung-Sol. I picked them up on eBay and when I heard how fine the SQ was they were already sold out. Had some bad luck with tubes on eBay so I never buy more than one pair to try out first, this was one case I should have stocked up. Go figure. Not trying to discourage anyone from trying the 12B4A/5755 might work just fine with your DAC and phones.

 

[EDWARIS]

8,32,300 ohm 1/4” jacks.
Revised transformers.
Revised power supply.
Blessed by Elves. Keebler style.

cool, thank you) I see it can drive speakers as well? what kind of speakers would be good?

and what is dimensions and weight of this amp? I am thinking about new tube amp for me, preferable 300b or 2a3, this one definitely in my short list.

 

[buke9]

Finally tried the 12B4A/5755 with two different brands of matched 12B4A's and a very good 1950's Western Electric clear top 5755/420A using the convertor. First thing I noticed was soft bass: bass was there but sounded soft with no punch or heft. This was with either matched pair. I only had the one 5755 to try. Mids and treble were fine and the sound stage with GE tubes had good depth. Took the 12B4A's out put the 1626 back in and bass returned to normal. In my rig the 5755 sounded no better than a good 12SL7GT so the 12B4A/5755 is not for everyone. It is not that expensive to try out and your experience may be different than mine. Seems system dependent.

I lucked into a particularly nice matched pair of RCA 1626 from 1943 that came in an RCA box, not the generic wartime beige boxes you normally see. These are the best sounding RCA 1626 I have ever heard and are very close to Tung-Sol. I picked them up on eBay and when I heard how fine the SQ was they were already sold out. Had some bad luck with tubes on eBay so I never buy more than one pair to try out first, this was one case I should have stocked up. Go figure. Not trying to discourage anyone from trying the 12B4A/5755 might work just fine with your DAC and phones.

I was just looking at the more power output aspect of the combo as I would love a bit more power for my Abyss as they do pretty well with the Kenzie but a bit more power would be just the thing as they bring the bass on their own and maybe softening up a bit would not be a bad thing.