EF86 vs. 12ax7?
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Hot _Grits
Buttery Toneologist
Re: EF86 vs. 12ax7?
well, it's a much gainier preamp valve. It's difficult for me to judge any inherent sonic difference, as I've only compared them in differing circuits. I can tell you the amps I've tried with them sound stellar, though we're talking spendy amps: 65 london and soho and and the new vox handwired ac15.
One major issue with the EF86 is that the new ones are extremely prone to microphony. If I do get around to buying a 65 London or Soho in future, I'll certainly be investing in NOS EF86s and Shockmounted roadcases. It's also another good reason to go head/cab if designing or buying an EF86 amp.
well, it's a much gainier preamp valve. It's difficult for me to judge any inherent sonic difference, as I've only compared them in differing circuits. I can tell you the amps I've tried with them sound stellar, though we're talking spendy amps: 65 london and soho and and the new vox handwired ac15.
One major issue with the EF86 is that the new ones are extremely prone to microphony. If I do get around to buying a 65 London or Soho in future, I'll certainly be investing in NOS EF86s and Shockmounted roadcases. It's also another good reason to go head/cab if designing or buying an EF86 amp.
Rich_S
HomeGrownToneBrewologist
Re: EF86 vs. 12ax7?
Actually, the new EF86's were not built well for several years. However, it seems that in response to high demand from several of the boutique amp builders (65, Dr. Z, etc.) the tube manufacturers have been working on their EF86's and are beginning to get them right. The German RFT EF86 is supposed to be pretty good, both in sound and in lack of microphonics.
Link to EF86 page at Tube Depot
I asked a similar question to this recently (something to the effect of AC15 vs. Lightning?) wondering how the EF86 amps compare. Dave Hunter wrote a really good review of the vintage AC15 several months ago in Vintage Guitar. I have a spare Bogen PA head around, and I think I'm going to build up a EF86-channel-only AC15 in it, just to compare it to my 12AX7-based 18 Watter. They should make quite a pair.
Actually, the new EF86's were not built well for several years. However, it seems that in response to high demand from several of the boutique amp builders (65, Dr. Z, etc.) the tube manufacturers have been working on their EF86's and are beginning to get them right. The German RFT EF86 is supposed to be pretty good, both in sound and in lack of microphonics.
Link to EF86 page at Tube Depot
I asked a similar question to this recently (something to the effect of AC15 vs. Lightning?) wondering how the EF86 amps compare. Dave Hunter wrote a really good review of the vintage AC15 several months ago in Vintage Guitar. I have a spare Bogen PA head around, and I think I'm going to build up a EF86-channel-only AC15 in it, just to compare it to my 12AX7-based 18 Watter. They should make quite a pair.
crusty philtrum
Vintageologist
Re: EF86 vs. 12ax7?
Hi
The 12AX7 is a dual triode valve (tube), the EF86 is a pentode. The '86 has more gain than one half of a 12AX7, but the 'AX7 can get more gain with the 2 halves in series, which is usually (but not always) how they are wired.
The '86 sounds darker and fuller, the 'AX7 will sound somewhat more glassy and have more sparkle (assuming they were in circuits that were similar, of course the circuitry can be designed to tweak their characteristics in other directions), but what i say is a general trait.
I have built many amps based on the Vox AC4, which is simply an EF86 preamp into a single EL84 power valve. (GREAT tone !! Not real sparkly, but they sound fat, like a big amp going hard, brilliant for recording). I have built a Matchless/Vox based amp that has 1 channel using an EF86 (with a simple 6 position rotary tone switch) and the other channel has a couple of 12AX7's (the Vox 'Top Boost' channel). In that circuit, you can really hear the difference (read any Matchless DC30 reviews to get the idea). The EF86 channel is powerful and quite dark compared to the AX7 channel, and to my way of thinking, clearly illustrates the differences.
I have been a big fan and user of the EF86 for many years, as I enjoy their strong and full-bodied sound. Yes, it is known that they can be microphonic. In the small AC4 amps, 'combo' use is not an issue with only 4 watts (a LOUD 4 watts, though, i must say !!). In 18 - 30 watt amps, as Hot-Grits points out, it can be an issue. I usually build heads and personally i never run a head sitting on a speaker cabinet. I have sourced some beautiful and fully serviceable shock-mounted sockets from old European tape recorders and record players. I had a 1960's Selmer Thunderbird amp until recently, it was a 50 watt combo with an EF86 (as well as a 12AX7) in each channel, shock-mounted sockets, and a pair of Celestion 12's....that thing could really thump and kick, and never did i have any microphophony (?) issues.
Oh yes.....something else i and a mate who has great ears have noticed .....any EF86 gear tends to....give the guitar notes a 'bloom'.....a kinda swelling after the initial attack.....not so much in volume perhaps but harmonically...it's very subtle but it's there...it may account to some degree to the lower 'sparkle' factor and perhaps to the 'fatter' aspect. It is a lovely sound to my ears.
If you like more in the glassy and sparkly area of tone, probably stick with the 12A?7 family. If you like a little beef and one foot (or both) on the dark side, the '86 is great. There has been a great deal of interest and use of this valve in recent times, and it is interesting for me to see, as i have been using it in amost everything i have built over the last 15 years (small amps, meduim powered amps, valve spring reverb units and microphone pre-amps). There was a period about12 or 13 years back when i think no-one was manufacturing them, and i became very guarded about using them, but then Sovtek brought one out. Since then, many other manufacturers offer their versions. I have used quite a few and i find it hard to say whether any particular brand tends to be microphonic, i think occasionally one might find a microphonic issue within any of the brands. Most of my experiences have been good, however.
Hi
The 12AX7 is a dual triode valve (tube), the EF86 is a pentode. The '86 has more gain than one half of a 12AX7, but the 'AX7 can get more gain with the 2 halves in series, which is usually (but not always) how they are wired.
The '86 sounds darker and fuller, the 'AX7 will sound somewhat more glassy and have more sparkle (assuming they were in circuits that were similar, of course the circuitry can be designed to tweak their characteristics in other directions), but what i say is a general trait.
I have built many amps based on the Vox AC4, which is simply an EF86 preamp into a single EL84 power valve. (GREAT tone !! Not real sparkly, but they sound fat, like a big amp going hard, brilliant for recording). I have built a Matchless/Vox based amp that has 1 channel using an EF86 (with a simple 6 position rotary tone switch) and the other channel has a couple of 12AX7's (the Vox 'Top Boost' channel). In that circuit, you can really hear the difference (read any Matchless DC30 reviews to get the idea). The EF86 channel is powerful and quite dark compared to the AX7 channel, and to my way of thinking, clearly illustrates the differences.
I have been a big fan and user of the EF86 for many years, as I enjoy their strong and full-bodied sound. Yes, it is known that they can be microphonic. In the small AC4 amps, 'combo' use is not an issue with only 4 watts (a LOUD 4 watts, though, i must say !!). In 18 - 30 watt amps, as Hot-Grits points out, it can be an issue. I usually build heads and personally i never run a head sitting on a speaker cabinet. I have sourced some beautiful and fully serviceable shock-mounted sockets from old European tape recorders and record players. I had a 1960's Selmer Thunderbird amp until recently, it was a 50 watt combo with an EF86 (as well as a 12AX7) in each channel, shock-mounted sockets, and a pair of Celestion 12's....that thing could really thump and kick, and never did i have any microphophony (?) issues.
Oh yes.....something else i and a mate who has great ears have noticed .....any EF86 gear tends to....give the guitar notes a 'bloom'.....a kinda swelling after the initial attack.....not so much in volume perhaps but harmonically...it's very subtle but it's there...it may account to some degree to the lower 'sparkle' factor and perhaps to the 'fatter' aspect. It is a lovely sound to my ears.
If you like more in the glassy and sparkly area of tone, probably stick with the 12A?7 family. If you like a little beef and one foot (or both) on the dark side, the '86 is great. There has been a great deal of interest and use of this valve in recent times, and it is interesting for me to see, as i have been using it in amost everything i have built over the last 15 years (small amps, meduim powered amps, valve spring reverb units and microphone pre-amps). There was a period about12 or 13 years back when i think no-one was manufacturing them, and i became very guarded about using them, but then Sovtek brought one out. Since then, many other manufacturers offer their versions. I have used quite a few and i find it hard to say whether any particular brand tends to be microphonic, i think occasionally one might find a microphonic issue within any of the brands. Most of my experiences have been good, however.
crusty philtrum
Vintageologist
Re: EF86 vs. 12ax7?
I've built a few 18 watters and used the EF86 extensively, but never put an '86 channel into an 18 watter. However, the Matchless/Vox inspired amp i built myself runs 4 x EL84's with each pair being individually switched, so i can hear a single pair of '84's with an '86 in front. I like the sound greatly, and use it much more than the 12AX7 channel. But it's a matter of personal preference.
The Marshall 18/20 watt power circuit is, from memory, much like the Vox (and Matchless) power stage, so my speculative answer to the question of how an 18 watter with EF86 would sound is.....i imagine it would be very much like an original Vox AC15.
Trinity amps apparently make kits based on the 18 watt and Matchless amps, and i believe they have a version of the 18 watt with an added EF86 channel. There is good reading to be had on their forums, but when i looked recently, their site was temporarily out of action. Check it out from time to time, when it's up again you could learn a lot about the EF86 applications and sounds from the contributors there.
I've built a few 18 watters and used the EF86 extensively, but never put an '86 channel into an 18 watter. However, the Matchless/Vox inspired amp i built myself runs 4 x EL84's with each pair being individually switched, so i can hear a single pair of '84's with an '86 in front. I like the sound greatly, and use it much more than the 12AX7 channel. But it's a matter of personal preference.
The Marshall 18/20 watt power circuit is, from memory, much like the Vox (and Matchless) power stage, so my speculative answer to the question of how an 18 watter with EF86 would sound is.....i imagine it would be very much like an original Vox AC15.
Trinity amps apparently make kits based on the 18 watt and Matchless amps, and i believe they have a version of the 18 watt with an added EF86 channel. There is good reading to be had on their forums, but when i looked recently, their site was temporarily out of action. Check it out from time to time, when it's up again you could learn a lot about the EF86 applications and sounds from the contributors there.
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