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Options for replacing EF86? E180F?

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rotation

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#1
Hi,

I'm working on a tube microphone preamplifier where input tube is EF86/6267. I find this tubes quite noisy, some of them are ok from beginning but later become noisy. I could simply change the tube, but prices are quite high and many new tubes are noisy from beginning.

Since i love the sound of EF86 input stages i would really like to change this tube with another sharp cutoff pentode tube. I can get SQ, gold pin E180F or normal version of EF184. Both are about 5 times cheaper than EF86 and stock is almost unlimited.

Schematic of preamplifier i'm working on is here:
http://img56.photobucket.com/albums/v172/gyraf/REDD47.gif
Input stage looks exactly like example for AF amp in Philips datasheet for EF86, but i can't find nothing similar for E180F.

So, what should i do to replace EF86 with E180F? I compared some values and E180F have higher Ia, Gm, Mu and lower Ri.
I guess i have to change Ra, Rk, Rg2.
If you look at schematic of mic pre there is 330k resistor which loads EF86. Does it remain the same for E180F?

Yeah, many questions. I would be very happy if anyone tells me how to start so i can experiment.
Btw, anyone have experiences in replacing this two tubes?

Regards from Miha
 
#2
rotation said:
Hi,

I'm working on a tube microphone preamplifier where input tube is EF86/6267. I find this tubes quite noisy, some of them are ok from beginning but later become noisy. I could simply change the tube, but prices are quite high and many new tubes are noisy from beginning.

Since i love the sound of EF86 input stages i would really like to change this tube with another sharp cutoff pentode tube. I can get SQ, gold pin E180F or normal version of EF184. Both are about 5 times cheaper than EF86 and stock is almost unlimited.

Schematic of preamplifier i'm working on is here:
http://img56.photobucket.com/albums/v172/gyraf/REDD47.gif
Input stage looks exactly like example for AF amp in Philips datasheet for EF86, but i can't find nothing similar for E180F.

So, what should i do to replace EF86 with E180F? I compared some values and E180F have higher Ia, Gm, Mu and lower Ri.
I guess i have to change Ra, Rk, Rg2.
If you look at schematic of mic pre there is 330k resistor which loads EF86. Does it remain the same for E180F?

Yeah, many questions. I would be very happy if anyone tells me how to start so i can experiment.
Btw, anyone have experiences in replacing this two tubes?

Regards from Miha
Click to expand...


How about D3A, the German Post Office Pentode? You can get these on eBay for about $11 each last time I checked. (U.S. types like 7788 and 6688 might be worth a look as well.) Yes you will need to figure out the optimum operating points for any tube you substitute.. These high transconductance types all run at very high currents compared to EF86, but are much quieter. New plate, screen, cathode resistor values will be required..
 
#3
Re: Re: Options for replacing EF86? E180F?

kevinkr said:



How about D3A, the German Post Office Pentode? You can get these on eBay for about $11 each last time I checked. (U.S. types like 7788 and 6688 might be worth a look as well.) Yes you will need to figure out the optimum operating points for any tube you substitute.. These high transconductance types all run at very high currents compared to EF86, but are much quieter. New plate, screen, cathode resistor values will be required..
Click to expand...

Hey,
6688 is E180F and D3A is EF184.. I can get this tubes for 2,5 euros or even cheaper. I would like to focus on E180F/6688 because i can get SQ version for same price.

Miha
 
#5
Re: Re: Re: Options for replacing EF86? E180F?

rotation said:


Hey,
6688 is E180F and D3A is EF184.. I can get this tubes for 2,5 euros or even cheaper. I would like to focus on E180F/6688 because i can get SQ version for same price.

Miha
Click to expand...

Doubt there is a much better made tube than the Siemens & Halske D3A, SQ or not.. The German Post Office was very particular about what they used in their equipment. Note that Philips made an SQ version of the D3A, and I don't see any reference in the vade mecum or elsewhere that cites the EF184 as an equivalent to the D3A and comparing data sheets indicate they are different tubes. Pin outs and transconductance are different. IMO SQ tubes are nice, but not necessarily a reason not to consider other types which might be comparable in quality. Your choice obviously.. 😀
 
#7
D3A is not an EF184

D3A is no way an EF184! D3A is a supertube by all means with no substitute! Only some Russian tubes are close but very inconsistent in performance.

e180f can also be substituted by 6J9p(which is excellent sounding and avalable).

P.S I love e180f sound! too bad I only have 2 :bawling:

Is there any spare one I can get from you as I am using these in my favorite SE pre?
 
#10
rotation said:


Guy have them all 🙂 Have you maybe tried to replace EF86 with E180F or any other similar tube? What do you suggest?
Click to expand...

The first one (6J32P) may be used with no modifications; the last 2 need more current. 6J52P is similar to D3A. 6J53P has anode made of titanium so can keep up with powers needed for best linearity.

The "guy" knows them all well.


Enjoy!
 
#11
Re: D3A is not an EF184

panos29 said:
D3A is no way an EF184! D3A is a supertube by all means with no substitute! Only some Russian tubes are close but very inconsistent in performance.

e180f can also be substituted by 6J9p(which is excellent sounding and avalable).

P.S I love e180f sound! too bad I only have 2 :bawling:

Is there any spare one I can get from you as I am using these in my favorite SE pre?
Click to expand...

Hi,
is E180F in your preamp wired as triode or pentode? Would you show schematic of it or any other example with pentode connection of this tube? I don't know how to start replacing EF86, so example might be a good start.
Btw, i built my preamp p2p so i can replace tubes without a problem..

Regards from Miha
 
#12
EF40 - though you will need a B8A rimlock socket. The EF40 is pretty much an exact equivalent and is cheap. The best part about the rimlock socket is that in fact it 'locks' the tube down into the base since the tube is centered by the nub on the side.

Majority of the production is Phillips, though I've owned Tungsram and Siemens too.

EF40:
http://www.tube-classics.de/TC/Tubes/Common EF40/EF40.htm

sockets look like this:
http://cgi.ebay.com/B8A-Philips-Cer...ryZ73375QQssPageNameZWDVWQQrdZ1QQcmdZViewItem


Even though EF86 prices have risen, I would probably stick with it since there are so many variations of this tube.
 
#13
Hello ,
EF86 predecessors and similar tubes :
EF6 , EF12(k) , EF40 , EF804(s) , E80F , EF806s............
The EF12k and EF804s were used in many vintage german studio amps without any problems for years and years ( V72 and similar amps ) , the V74 used 5654 and E180F , the last one as output tube .
Circuit from all this studio stuff you can find here :

http://audio.kubarth.com/

Regards , Alexander .
 
#16
7n7is said:
How about the 7199?
Click to expand...

Noo...definitely not.. the 7199 is on the obscure list (high price!) and it isn't screened either.
As I'm old fashioned, your original question mentions re microphonics and noise, cue's me straight on on a 6BR7 or 6J7, both are screened, pretty similiar but some circuit surgury is required. Take your choice, B9A, or Ioctal +topcap, resp. The rimlock variants are also good.

The EF184 is a totally different breed and falls in the 12BY7A
class of video drivers.

If you feel deterred by chassis/electrical changes, then the only hope is to pay EF86's as they stand. prices do vary.

richj
 
#18
Hi
Panos; my PMs seem to be disabeled by moderators for unknown reaon (to me). I will contact you by email...
I managed to find this circuit with E180F:
http://margo.student.utwente.nl/el/tubes/schema/preamp/fb-e180f.gif
To me it looks like phono preamp and it is the only circuit with this tube (pentode connection) i could find.
Values for anode and G2 resistors are exactly the same as for EF86 on my schematic. Is this correct, i was told this tube should have more anode current.
Also, i don't understand how is grid bias achieved on schematic of mic preamp i showed. Is it done with 100k resistor? To me it looks like 100k is part of circuit for transformer..
I wish i could find more examples of pentode connected E180F. If anyone have any please let me know.

Regards from Miha
 
#19
EF80 equivalent to E80F?

Klimon said:
E80F should work in most circuits as drop-in for ef86; this might be exactly what you're looking for.
Click to expand...

Is the EF80 interchangeable with the E80F (at least electrically)? Can some other members confirm E80F is a drop-in for EF86. I have a pair Quad IIs which use 2 pairs of EF86, which have become quite expensive.

Having a number of E180F I'm interested in this thread for any information about substituting the EF86 with the e180f.

Joe A
 
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