[steve f]

Question: Why don't people try single ended pentodes. For about 20 years single ended triodes have dominated the single ended niche.

Steve

[Guy 13]

Hi all Audio Circle members.

Single ended triode vs single ended penthode.

Single ended penthode will as far as power is concerned.
But what about sound qualitties ?

Any one can share his experience having made side by side comparaison?

I have a single ended triode Decware SE84C+ and a
single ended penthode Niteshade Audio SE-10.

Which one is better.

Hummm hard to say.

They are different,
each one with his qualities and weaknesses...


Guy 13

[steve f]

Thanks Guy,
I never paid attention to the Niteshade site. Ooops. The concept is interesting, with parallel power tubes and all. I have to do some study work and catch up. I really don't care much for regular SET amps. I owned a Decware for awhile but sold it. I like air and slam better than smooth midrange I guess. I hope we get more comments about the Niteshade products, even though this isn't their forum link.

Steve

[Scott F.]

I'm a die hard single ended guy, 300Bs, 2a3s, 45s, 211s.

Single ended pentodes just don't sound the same as a triode. I'm not sure why. I've listened to several and they simple don't have the nuance and presence of a decent triode. I'm not sure measurements can record the differences (much to the dismay of many). When you listen side by side they're just different. So, I stick with triodes...but that's just me. YMMV

[DaveC113]

Thanks Guy,
I never paid attention to the Niteshade site. Ooops. The concept is interesting, with parallel power tubes and all. I have to do some study work and catch up. I really don't care much for regular SET amps. I owned a Decware for awhile but sold it. I like air and slam better than smooth midrange I guess. I hope we get more comments about the Niteshade products, even though this isn't their forum link.

Steve

A good SET will have plenty of slam and air when used with the right speakers. A lot of this depends on the power supply and OPTs, and IMO it is difficult (impossible, really) to achieve in a reasonably priced commercial SET amp. Good chokes, caps and OPTs cost a lot of money. I have over $200 just in PS caps in my SET amp and preamp and even more in the amp's OPTs. If you spend in parts what the Decware costs as a finished product you will be in the ballpark...

As far as pentodes, from what I remember the best way to do it is to have a separate power supply for the pentode grid. Ultralinear operation is much more common, which is basically positive feedback from the OPTs to a pentode tube's grid and can about double power output. I have efficient speakers and prefer running my EL34s triode strapped in my amp. UL isn't bad but does add some distortions.

[steve f]

Thanks Scott,

You are the other side of my coin. I respect that too. I have yet to listen to a single ended pentode. Most non SET amps are PP ultralinear or PP pentode. I have a single ended class A OTL but it puts out only a watt and a half! ( I don't see how some companies claim to build large class A OTL's as you would need industrial power available.) Sounds glorious though, and it is the only SE amp I like so far. Perhaps there are just more people who are happy with AET amps so few have tried SEP's. Building for a known market.

Steve

[steve f]

Thanks Dave,

Since I'm still online and started this topic  .
Yes speakers play a huge role in SET land. You are correct; IMO ultralinear does add some distortion.

steve

[Ericus Rex]

You are correct; IMO ultralinear does add some distortion.

That's the nature of the tube.  Regular pentode operation is by far the most distorted.  Ultra-linear is a compromise and falls between triode and pentode on the distortion scale.

[FullRangeMan]

Thanks Scott,

You are the other side of my coin. I respect that too. I have yet to listen to a single ended pentode. Most non SET amps are PP ultralinear or PP pentode. I have a single ended class A OTL but it puts out only a watt and a half! ( I don't see how some companies claim to build large class A OTL's as you would need industrial power available.) Sounds glorious though, and it is the only SE amp I like so far. Perhaps there are just more people who are happy with AET amps so few have tried SEP's. Building for a known market.

Steve

Interesting this your amp, SE and OTL, looks great sound with a hi SPL speaker.
Would you identify it or supply the web site link??
Thanks

[doorman]

Try: http://www.transcendentsound.com
-follow the product links--
don

[FullRangeMan]

Try: http://www.transcendentsound.com
-follow the product links--
don

Thanks, you most kind. This is a SE Parallel with various tubes, I though it was a single tube amp.

[Jon L]

A good SET will have plenty of slam and air when used with the right speakers. 

"The right speakers" is always the rub with single-digit power SET's.  You see so many people struggle, often years, to get that speaker "right."  A good SEP allows that rub to be a bit less stringent IME, although I would say I still prefer a good 2-3 watt SET overall.

[FullRangeMan]

Conservatively a 211/845 can give around 15W and  a 805 or GM70 can delivery 20W, which can solve the problem speaker compatibility.
But many audiophiles cant live without the low power Triode sound, which is understandable.

[Guy 13]

Hi all Audio Circle members.

Sometime ago I did a comparison between my Decware SE84C+ (2wpc) and my Niteshade Audio NS-10 (10wpc) with my GR Research V1 (98db efficient) speaker.

At the time, my listening room was (Huge) with dimensions of 25’ X 30’ with a 9’ ceiling.

The Decware could drive the V1 at very respectable listening level, but the volume control was at its maximum position, therefore I did not have any headroom power to spare.

With my Niteshade, I had plenty of headroom and more impact and punch and the volume control was only at 12o’clock.

Of course in both cases, the two 12” GR servo sub (Two on each side) were driven by a 370 watts plate amplifier (One for each channel), that helps a lot.

At a more reasonable listening level and in a smaller listening room, the Decware 2wpc amplifier would have been fine.

With a 2wpc amplifier driving 98db efficient speakers,
you only need 1/16 watt of power to drive the speaker at a normal listening level of 86db and you still have 16X headroom of power available.
(Someone correct me if I am wrong)

As for the better mids between the SET and SE Penthode, my 64 years old ears could not really tell the difference, not that there is not one?

Hope this help a little.

Guy 13

[DaveC113]

Hi all Audio Circle members.

Sometime ago I did a comparison between my Decware SE84C+ (2wpc) and my Niteshade Audio NS-10 (10wpc) with my GR Research V1 (98db efficient) speaker.

At the time, my listening room was (Huge) with dimensions of 25’ X 30’ with a 9’ ceiling.

The Decware could drive the V1 at very respectable listening level, but the volume control was at its maximum position, therefore I did not have any headroom power to spare.

With my Niteshade, I had plenty of headroom and more impact and punch and the volume control was only at 12o’clock.

Of course in both cases, the two 12” GR servo sub (Two on each side) were driven by a 370 watts plate amplifier (One for each channel), that helps a lot.

At a more reasonable listening level and in a smaller listening room, the Decware 2wpc amplifier would have been fine.

With a 2wpc amplifier driving 98db efficient speakers,
you only need 1/16 watt of power to drive the speaker at a normal listening level of 86db and you still have 16X headroom of power available.
(Someone correct me if I am wrong)

As for the better mids between the SET and SE Penthode, my 64 years old ears could not really tell the difference, not that there is not one?

Hope this help a little.

Guy 13

Impact and punch are highly dependent on the amp's power supply. You were hearing a lot more than the differences between power output capabilities. Assuming you're not clipping your 2 watt amp...

[Guy 13]

Impact and punch are highly dependent on the amp's power supply. You were hearing a lot more than the differences between power output capabilities. Assuming you're not clipping your 2 watt amp...

`

Hi Dave.
According to Decware the power supply on their SE84C+ is 5X what is normally required.

For my Niteshade NS-10,
I am not sure, maybe Blair could comment.

Guy 13

[planet10]

A SET usually has no global feedback. An SE pentode without feedback is a current amplifier... to get the most out of it, you need a speaker specifically designed to be driven with a current amplifier.

So most SEP have feedback of some sort, so that they can drive more typical speakers.

In our SE EL84 journey we ended up with Schade feedback (as in an RH84) and an amplifier we preferred the sound of. Regulating the screens (something we have not done yet) should extend the amp's quality.

dave

[Quiet Earth]

I really don't care much for regular SET amps. I owned a Decware for awhile but sold it.

I don't think Decware ever made a single ended triode amp with a real triode in the output. Or did they?

[planet10]

I don't think Decware ever made a single ended triode amp with a real triode in the output. Or did they?

AFAIK you are correct.

dave

[cheap-Jack]

Hi.

Question:
(1) Why don't people try single ended pentodes.
(2) For about 20 years single ended triodes have dominated the single ended niche.
Steve

(1) Simply because triode is more linear than a pentode. Click up the specs manual of a triode & a pentode, & compare the transfer curves of both. You will see the set of transfer curve of a triode is pretter straight.
BUT but the set of transfer curve of a pentode goes thru a right-angled like knee. It is this knee that limits the linear space available for signal swing magnitude.

Consequently, a pentode generates more 3rd & higher odd orders of harmonic distortions than a triode. Sonically a pentode sounds not as pleasant to our ears which dislike odd orders of harmonic distortion.

Also, a pentode O/P tube is much more critical on load impedance variation than a triode. Such as loudspeaker load which changes its impedance with the music signal frequencies, particularly at LF & HF. This will render a pentode to generate much more harmonic distortion. That's why negative feedback (NFB) is so often NEEDED for pentode O/P amps to cancel out the distortion.

Then it generates another problem:- it generates not too stable operation on music transients.

A triode O/P amp does not need NFB to cancel such distortions which are normally not generated by a triode.

All those make our ears find triode sounds better than pentode when used in preamp or power amp.

This is physics.

(2) Historically, tetrodes & pentodes were "invented" to boost up the low low O/P power of a triode at the expense of the sound quality due to higher distortions.

So to increase the O/P power of a low low O/P power triode, push-pull or SE parallel triodes are used. So Class A push-pull has been regarded as the lowest distortion power O/P amp design WITHOUT using any NFB vs pentodes.

It can achieve both best sounding quality & higher O/P power which pentode SE or PP cannot touch.

Personally I go for triode PP O/P stages for high power, low distortion & musical sounding. That's why I've converted my 50-year old Dynaco ST-70 to triode PP by triode-strapping its EL-34 O/P pentodes by using a unique Vg2 level shifter topology. Though it reduces its rated 35W O/P power to 15Wrms.
Yet such unique triode-strapping makes the music sound soooo much better than its origianl Ultra-Linear O/P design.

SE or PP, I go for triode PP. My many many hundreds of classical LPs tell me I have made the right choice.

c-J