• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

EL86 and speakers? 800 Ohm

EL86 and speakers ? 800Ohm

I have a philips amp with 4 EL86's and a speaker - 800ohms
It works really well.
My wife wants to trash the lot as the speaker is "old fashioned"
(now i know what a den is for)
So my question is related to the speaker ohms and the following post i found:
Power was rated at ~8 Watt into 800 Ohm. Much to my surprise it worked rather well with my 8 Ohm 92dB/1M speakers.

So the question is ifI want to purchase "modern speakers", and still get good sound, without damaging the amp or speakers, what ohm speakers can I connect?

Any reply on the subject will be appreciated.
Please no comments about replacing the wife, I did some sums and that worked out a bit expensive.



2003-01-18 7:57 am
Near London. UK
So the loudspeaker is old-fashioned, but the amplifier isn't?

Most modern loudspeakers are nearer to 4 Ohms than 8 Ohms. Can you not dress up the old loudspeker to look more modern? Perhaps add some labels saying "Turbo mega-bass", a photograph of a tweeter, paint the wood to look like plastic, etc?

Seriously, you will have trouble finding even a 15 Ohm loudspeaker these days.

Oh, and welcome to the forum!

thanks for the note.
So i guess modern depends on a persons analysis of "usefulness" and or perception.
The speaker is the only part she can see, it is a corner unit two tweeters and one woofer. The amp I have stripped out of the turntable cabinet as it was just occupying too much space.

I will post a different thread on the model of the amp etc. (Model AG9008)

Of course for me it is not a question of age (wines and vines have character, and improve with age)
I find no reason not to get this set up and running again - after the movers trashed the amp - found some NOS EL86 equivalents and look forward to using it. I need to build a box to keep little fingers aware from this. More from a safety factor as apposed to touching it.

Thanks for the note. yes a could just rebuid the speaker cab. - and will probably do that. Just has such a great sound.
hower back to the ohms, If I do want to use "comercially available speakers" are there any gotchas or smoke warnings?


2003-01-18 7:57 am
Near London. UK
Re: Modern

iharris said:
So I guess modern depends on a person's analysis of "usefulness" and or perception.

Absolutely. I'm guessing that your wife isn't a loudspeaker designer, so she isn't commenting on the unsophisticated cone material/profile etc, but more on the fact that it just isn't in the current "modern" style.

If you load your amplifier with a conventional loudspeaker you will greatly increase the distortion, but you won't blow it up - valve amplifiers are nothing like as frail as their silicon counterparts. (I just know somebody is going to immediately prove me wrong on this one.)

The "obvious" answer is to fit a mtching transformer between your amplifier and conventional loudspeakers. A 100V line transformer set to 10W into 8 Ohms would do the trick. Unfortunately, 100V line transformers are designed for PA and are terrible. Your amplifier would be great for 300 Ohm headphones, though.


Paid Member
2003-06-12 7:04 pm
Maine USA
> a philips amp with 4 EL86's and a speaker - 800ohms

Put the speaker drivers in "stylish" cabinets with a grille-cloth of your wife's fancy. Or put slip-covers on them when not in use.

That is a rare amp. One of the very few OTL (Output Transformer-Less) commercial amps ever sold. Futterman fans go to a lot of trouble to do what Philips did. It works only because of the hi-Z speakers; but many of them failed due to the very thin wire needed to wind them.

They are also probably some of the best $1 speakers ever made. The 1950s were full of junk, but also some very good stuff that didn't "look exotic".

> it worked rather well with my 8 Ohm 92dB/1M speakers.

It will make about 0.1 Watts. Just like Mr Pass's "First Watt" amplifer, mostly we do NOT need hundreds of watts for good sound. I know I had my fun with 1-Watt amps often worked far below clipping. However 0.1 Watts, even 1 Watt, in home-size speakers, is not "realistic performace levels". (I've had a piano and a piano recording in the same room: 160 watts of power in average-efficiency speakers, and the speaker was strained before the piano.) However, many folks never play at "realistic" levels, which may really be too much for a home-size room with neighbors.


2003-01-18 7:57 am
Near London. UK
I could give you all sorts of pseudo-technical baloney, but the plain fact of the matter is that with an 800 Ohm impedance, even bell wire is massively thick. I doubt very much that you could do anything with the loudspeaker wire to make an audible difference. Grille material, now that's another matter entirely...
Re: use a opt

Jaap said:
Some of the vintage 800 ohm amps of Philips also had a outputtransformer on board. I saw one a few days ago on Ëbay.
Go transformer hunting I would say

Some had OPTs (when used with EL84) but the EL86s (a pr used in an SRPP-like configuration) used a choke.



  • philips-800-pp-opt.jpg
    89.2 KB · Views: 1,012
I have one of those Philips EL86 amps and the speakers that go with it - very remarkable perrformance - so open & transparent, especially on vocals.

I'm amazed it works at all with low-Z loudspeakers.

The Philips 800 Ohm 9710M (the ones in my speakers) have an unusually wide response too. Discarding them is just plain nuts! One of the BEST aspects of mine is the beautiful 2-tone stained wooden cabinet, and its white grille. Prettier than almost any other speaker around.


  • 9710.jpg
    9 KB · Views: 466


2015-03-21 7:12 pm
yes this speakers and amps philips are beautifull

I construct some amps for guitar oriented whitout output transformer, direct output, and this for hifi or guitar are big's amps.

An the speakers only beautifuls and more, big response, big tone, hight full band, ...
I not have leters for descriptin this and sorprese my first time i construct this.

Have some persons more info or know the data of this bobine for the mode 8-16 ohms in the scheme of philips, characteristics of bobines, ¿Mh, ohms, etc?

The how connect standar speakers 4,8,16 ohm, whithout transformer of audio, at one OTL is very complex, can write one book only of this. The formule of philips whit bobine or inductance i think is one plus an acertate, but i not be how this affectate at de signal/ histeresis+etc, i see in the scheme one inductance whitout ferro/ histeresis, and other whit this for the 8/16 ohm output.

Some people here know this circuit or scheme of long or full?

Thanks and sorry my single writer english.
I am Spanis of Madrid.


Paid Member
2015-12-31 4:57 pm
The Hammond 119DA impedence matching transformer (12W) has a 600 ohm primary and 4/8 ohm secondary. It is often used to connect Philips high impedence amplifiers to modern speakers. I guess that a 6 ohm speaker connected to the 4 ohm secondary will be just fine.
If this is an OTL amp, and you are Forced to get rid of the 800 Ohm speaker,
you can easily change from an OTL to a transformer output.
Get a low impedance Push Pull output transformer that matches to 8 Ohms for the new speaker that pleases the lady.

800 Ohms is a little low for medium watt push pull transformers, but there is a trick.
Take a 3200 plate to plate transformer, and use one end of the primary to the center tap (half of the primary). Now, it is operating as a 800 Ohm primary (Z is proportional to N squared).


2015-03-21 7:12 pm
In this scheme the transformer of 800 ohms can see more how inductances or choke tansform of two poles, not?

Can this are inductances?, Values?,
Or references de one product similar?

Uffff if this are inductances of 800 to 8 and 16 oms, ...is good

I read in theory of acoplate by inductances in some OTL , but have today poor and short info of this.
Some more info?