I think that if your speaker have over 88db for me the sound of the 211 is better and easy to drive and don´t need NFB,
211 bias -70v with a d3A, E280f or with 6e5p ( with preamp ) have a very good sound.
Source follower change the gentle sound of the tube for me.
My last 211 monoblock
Load with CCS or gyrator low Z, you will have a very good amp.
211 bias -70v with a d3A, E280f or with 6e5p ( with preamp ) have a very good sound.
Source follower change the gentle sound of the tube for me.
My last 211 monoblock
Load with CCS or gyrator low Z, you will have a very good amp.
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I would like to do , which one dht do you recommend, I use normally the 6e5p and I am very happy, I think that is one the best tube driver.
i have 6e5p .... sound is good but not best . i used vt25 and b405 philips ....re074 telefunken ....
dht tubes are different world of sound .my friends 211 amp has 3 dht tubes .
211.....vt25.....b405.
8k output Amorphous chock....oil caps ....1050v ....12w output .
211.....vt25.....b405.
8k output Amorphous chock....oil caps ....1050v ....12w output .
yes difficult so from 10 years before i start to buy dht tube for drive.you can use 2a3 or 6b4g
Hoonan why you do use 8k only I think that 211 run better on 12k to 16k, I am waiting to finish the case of my new 211 with custom made with 14k OPT
Stick with Thoriated Tungsten...🙂 801A, HY40 come to mind. 842 if you can find them. 811-30 is another...as is 811-10.
cheers,
Douglas
cheers,
Douglas
H-S, that presents a load significantly below the plate resistance of the driver element( the triode connected audio beam tube ).
I am doing a PP cathode drive amp. It uses a 600R line driver output TX secondary to power the cathode circuit. The front end is two stage; an EL84 LTP driving Plate-to-grid FB'd TV sweeps, likely 6CB5A's. The finals are zero biased. With the zero bias, I take the bias circuit out of the equation; I don't want another power supply on the grids for when they go positive. The finals are HY51A's with B+ adjusted to set their idle current and attached to a 10k a-a OPT.
cheers,
Douglas
I am doing a PP cathode drive amp. It uses a 600R line driver output TX secondary to power the cathode circuit. The front end is two stage; an EL84 LTP driving Plate-to-grid FB'd TV sweeps, likely 6CB5A's. The finals are zero biased. With the zero bias, I take the bias circuit out of the equation; I don't want another power supply on the grids for when they go positive. The finals are HY51A's with B+ adjusted to set their idle current and attached to a 10k a-a OPT.
cheers,
Douglas
Hi,
there is an excellent circuit at the Lampizator Website from the austrian "Röhrenklinik".
The circuit is for tuning a Music Angel 845 MKIII.
there is an excellent circuit at the Lampizator Website from the austrian "Röhrenklinik".
The circuit is for tuning a Music Angel 845 MKIII.
The usual B+ levels associated with 845's leave much latitude in driver/voltage amplification stage design...there are many volts to play with...🙂 if you want a triode driver, find a few type HY40. Think 3 6SN7's in parallel with a 40W plate and a Thoriated Tungsten cathode.
cheers,
Douglas
cheers,
Douglas
Hope I got this right... does not seem like "significantly" below.
Input impedance of 845 = (1200+10000)/(5.65+1) = 1,684
Plate resistance of 6CA7 (triode) = 2,556
Maybe for an active setup in which you use that amp for lows and/or mids. The interwinding capacitance of a 20k:8k transformer will be so high that you are lucky getting a -3dB point at 18kHz.
IDK about that jazbo...input impedance seems much more comparable to output impedance. IIRC for cathode followers it heads for 1/gm, and from the papers I have read, at a first order the number comes out to be 2/gm.
cheers,
Douglas
cheers,
Douglas
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