[PromitheusAudio]

Are you guys fed up with single ended amps with flea power output and can't seem to work with "normal" speaker. If so read on

I was always interested in this tube, the 13e1. Great tube. Big and nice. When done correctly can give you an output power of 30watts SET.
That was 4 years ago, recently a great friend of mine ask whether an amp can be made with the 13e1 tube and he send me a pair to try.

THey were STC branded 13e1

Wow, great sound, tonally good similar to the 2a3, eventhough its a tetrode strap to a triode. But can't compare them with current production tubes.
all 13e1 are NOS british made,  so already they are far above the current production "sound".

But what i really like about them is that they require a low voltage to work (they need only 400volts) , good damping factor, easy to drive which in turns makes it an affordable tube for the power rating of 30watts. Plus it looks kind of nice.

The tubes eventhough they were rare is not that expansive around USD200-300 a pair which works out to be okay considering they are NOS and okay for its power output

Bottom, i like the sound and would be exploring source to find more of this tubes. So far they seem to be available from the UK.

Currently i am driving them with a 6550 via an interstage. The input tube is a 6922 which is direct reactance choke loaded to the 6550.

Here are some pics of the unit

[JoshK]

Hi Nic,

Very cool.  Glad to see someone else found a good use with them besides Morgan Jones (Glass Palace amp).  The price is the only thing that has kept me from getting some.  You'll have to PM me your source.  Ebay prices for these that I've seen commanded quite a lot.

[PromitheusAudio]

At onetime there was 2pcs on ebay each USD130 and the seller is in the US

http://cgi.ebay.com/1-Or-More-Tube-13E1-Single-Ended-DIY-POWER-AMPLIFIER_W0QQitemZ310000474913QQihZ021QQcategoryZ50598QQrdZ1QQssPageNameZWD1VQQtrksidZp1638.m118.l1247QQcmdZViewItem was from the US


I get them from Billington UK valves. THey work to be around 55 pounds when you buy a certain amount. not cheap but do bear in mind this are NOS power tubes and they are about the same price as chinese and russian 300b.


THe main reason they are so expansive is because they were only made in limited amounts and i believe made by the british only.
Cheers
nicholas

[JoshK]

I saw those offered by "2A3", and he seems be to a good guy.  His prices are, IMHO, on the high side, but not unreasonable.  He however, was willing to do matching and pairing when you contact him.  I enquired about some other tubes from him in the past and he was willing to do some legwork to answer some prior questions.  This puts him a step above some of the sellers on ebay.

Thanks for the suggestion of billington.

Are you offering 13E1 amps?  How much?

[tanchiro58]

Hi Nick,

Do the 13E1 amps can drive any speakers or only high efficient speakers? How about impedances? I do not see any specs on your website? I am interested too. Let me know how much do they cost. Thanks.

Tan

[PromitheusAudio]

At 30 watts most speakers can be driven. I am driving my NS1000.
They are made for 8 ohm speakers but since we made our own OPT, designing any impedance taps is not a problem.

The pricing of the tube depends on how much i finally pay for them. We get 10% tax on valves here. So the expected price for this is from USD1900 to USD2000.

From a friend of mine in Australia, he had received some faulty 13e1 from billington and told Billington about it, they replace them with new ones without any fuss. Seems like a good person to deal with especially with NOS tubes.

[awkwardbydesign]

Hi Nick,
I am happily running in my new TVC, and saw this thread.  I am using an active x-over and need an amp for the bass.  The mid/treble uses a pair of 20w Ming Da 805 SETs, and the bass speakers are isobaric.  That means either 4 or 16 ohm loading, so could the OPTs have 4, 8 & 16 ohm taps?  Also how low would they go?  I would be crossing over at 130 or 200Hz.

Richard.

[PromitheusAudio]

Richard
Thanks for the comments on our TVC

Yes we can made them for 4, 8 , 16
The lowest frequency they go for a standard unit is 16hz but i can make them lower to 10hz if needed. The bandwidth for full operation is 16hz to 45khz -3db. So some of the bass has been traded for the high frequency

Its good you might even consider replacing your mid/treble amp

Cheers
Nicholas

[pbrstreetgang]

Since you have that high tax what if you provided the amps without the output tube to save us the money? How about a single chassis monoblock or a stereo 13E1? Very nice offering and it is very intriguing!

[PromitheusAudio]

Good idea on the tubes would be less USD280-300

Its not that high its 10% for tubes here.

Stereo may not be possible mainly because of the weight and heat issue. Even at monoblocks they do weight about 22kgs each monoblocks

The OPT and PT is the main weight problem plus there is dual power supply iron and chokes

[tanchiro58]

Hi Nick,

How long does it take to build the 13E1 monoblocks? I am considering to order a pair of any SET monoblocks with more power even though my speakers are high efficient but I could not decide which one would fit my consideration. I have listened to quite a few SET amps since I love their sound but they seems lack of bottom end. Do you have any suggestions? Thanks.

Tan

[PromitheusAudio]

Tan
This amps take about 3-4 weeks to get built
THis are normally build by me and tends to be a longer build time
For good bottom end it should be decide by the choice of output tube, transformer and capacitor choice
normally for good bass the gm70 has the best bass to my ears

[tanchiro58]

Tan
This amps take about 3-4 weeks to get built
THis are normally build by me and tends to be a longer build time
For good bottom end it should be decide by the choice of output tube, transformer and capacitor choice
normally for good bass the gm70 has the best bass to my ears

Nick,

What other choices of output tubes, transformers and coupling caps should I choose beside your 13E1 amps? What do you think of the 13E1 amps sounding in my system with modified Apollo preamp, modded DAC and my high efficient speakers (>97dB). I am using modded SB3 as a source with Felix PS.

How much do your GM70 amp cost (maybe 10K?)? I have heard Dehavilland GM70 amp and it is not so much impressive to my sonic tastes. For a solid and defined bottom end I agree with you that high efficient or conventional pricy speakers could be driven by a good design of push-pull amp with a SET sound like AN Japan new version PP amp that I listened to at CES 2008. They are very nice sounding with firm and punchy defined deep bass.

Tan

[PromitheusAudio]

if you want punchy bass, i feel it would be the choice of power supply capacitor

how so, i share with you my experience
we started our 300b amp with electrolytic capacitors, typical 300b, flabby bass, okay-okay highs
but when we swap all the caps to Mundoft tube cap and Mundoft polyproplyene capacitor for the cathode bypass.
the bass becomes really articulate and the highs are more airy and transparency. Ever since then, i decide not to use electrolytic capacitors
the more darker the tube the more benefit it gains from going electrolytic free.

Also having the tube run in fixed bias also increases bass control too.

The next thing would be how the tubes are coupled from driver to power tube. So far for good highs and bass i tend to prefer either direct reactance drive or interstage. this two topology has a lower phase shift than a capacitor. Phase shift always takes place at the extremes highs and bass. SO i believe you are also hearing some of this phase shift problem. The interstage has a phase shift maximum of 30degrees while a capacitor has 90degrees shift

There lots of tricks and design to improve bass in the errors of mechanical, electrical and electronic and of course tweaking

for the gm70 email me offline to find out more and whether it suites your system

[Frihed91]

I am looking for a 20+ Wpc SET (real or simulated) power amp or monoblocks  to drive my Stirling Broadcast LS3/5A V2s.  This is an 11-Ohm ave speaker whose load never drops below 8 Ohms and which presents a  fairly flat resistance (not reactive) load over 99.9% of its entire freq. range. They are currently easily driven by a pair of 25 Wpc Quicksilver Mini-Mites.  I prefer the DHT sound for SETs.

I have active SS and tube preamps from Blue Circle Audio in Canada.

How much power do your other two non-300 SETs deliver?

[PromitheusAudio]

The 6c33 does 18 watts
the gm70 does 30 watts, 50 max
i would say the 6c33, 13e1 and the gm70 would drive your speakers easily.
Just need to make sure that the tapping as made for 11 ohms.
THat way they are better suited power wise for the 3/5a.

[Milenko27]

How is the sound from the 6c33 monoblocks, reght now i have a el34 se amp, how is the 6c33 in the midrange?