Munich HighEnd 2024

[DasguteOhr]

No NOS for AA .
I bought to much expensive " NOS " tubes which turned out to be noisy .
I think it ll be new Svetlanas

but please the light grey labels, the ones with black labels are no longer Svetlana's. They have a high failure rate. out of 12 tubes, three died in the first year. This one are superb.

SED 6550C Svetlana -C- / Russia

die guten "winged C" aus St. Petersburg... AUSVERKAUF: wird aktuell (seit 2012) nicht mehr produziert. Nur noch solange Vorrat reicht.…

www.tubeampdoctor.com

 

[morricab]

Troels Gravesen
http://www.troelsgravesen.dk
DTQWT-212-mkIII

The 8008 front driver does not have a high-pass filter which has indisputable advantages but also limits power handling as it received the full bass load.

Yes, ok no rock concerts but for home listening more than enough power handling and as I have said the horn loading reduces excursion dramatically compared to sealed or vented boxes. So, you might burn a voice coil but you won't have over excursion issues.

 

[andromedaaudio]

but please the light grey labels, the ones with black labels are no longer Svetlana's. They have a high failure rate. out of 12 tubes, three died in the first year. This one are superb.

SED 6550C Svetlana -C- / Russia

die guten "winged C" aus St. Petersburg... AUSVERKAUF: wird aktuell (seit 2012) nicht mehr produziert. Nur noch solange Vorrat reicht.…

www.tubeampdoctor.com

These probably

Svetlana 6550 Matched | Tonefactory

Prijs per stuk. Worden bij afname van 2 stuks of meer gematched geleverd in paren of kwartetten.

www.tonefactory.nl

 

[DasguteOhr]

These probably

Svetlana 6550 Matched | Tonefactory

Prijs per stuk. Worden bij afname van 2 stuks of meer gematched geleverd in paren of kwartetten.

www.tonefactory.nl

Top tubes ,the four-digit number is the first two digits, the week, the last digits, the year. From my experience, the older the better.

 

[D.Duttilleux]

Yes, ok no rock concerts but for home listening more than enough power handling and as I have said the horn loading reduces excursion dramatically compared to sealed or vented boxes. So, you might burn a voice coil but you won't have over excursion issues.

The (D)TQWT hovers between a horn and a TL. The 8008 and the rear woofers both load the center horn and thus operate in a push-push configuration.
This also explains the relative vulnerability of the 8008: partly due to the lack of a HP, the stress put on the moving parts is higher, hence the lower power handling.
With this in mind, it's likely that, should someone decide to hook up a 500 watt Class D amp for a heavy house party, the diaphragm + surround of the 8008 will literally be torn to pieces even before the VC releases the magic smoke.

Which apparently happened twice:

"I have twice seen 8008 main driver's cone ripped apart from using e.g. 400 watt solid state amp - or lending the system to children's Saturday Night disco party. This from DTQWT mkII and DTQWT-12. Now, the DTQWT-12 was not made to play louder, only deeper. The main front driver still carries the full low-end signal and 95 dB sensitive speakers should simply not be fed 400 solid state watts. The voice coil was fully intact but the cone was just simply ripped apart. The other reason for this was that the speakers were supposed to energise more than 100 square metres rooms. This is equivalent to a smaller cinema space - and this is a completely different story. Before building speakers we need to analyse what kind of sound level we're aiming at, what is the room size - and volume, and what kind of amplifier are we going to use."

 

[morricab]

The (D)TQWT hovers between a horn and a TL. The 8008 and the rear woofers both load the center horn and thus operate in a push-push configuration.
This also explains the relative vulnerability of the 8008: partly due to the lack of a HP, the stress put on the moving parts is higher, hence the lower power handling.
With this in mind, it's likely that, should someone decide to hook up a 500 watt Class D amp for a heavy house party, the diaphragm + surround of the 8008 will literally be torn to pieces even before the VC releases the magic smoke.

Which apparently happened twice:

"I have twice seen 8008 main driver's cone ripped apart from using e.g. 400 watt solid state amp - or lending the system to children's Saturday Night disco party. This from DTQWT mkII and DTQWT-12. Now, the DTQWT-12 was not made to play louder, only deeper. The main front driver still carries the full low-end signal and 95 dB sensitive speakers should simply not be fed 400 solid state watts. The voice coil was fully intact but the cone was just simply ripped apart. The other reason for this was that the speakers were supposed to energise more than 100 square metres rooms. This is equivalent to a smaller cinema space - and this is a completely different story. Before building speakers we need to analyse what kind of sound level we're aiming at, what is the room size - and volume, and what kind of amplifier are we going to use."

That can't be quite right because the air will move to the region of lower pressure...ie. the mouth of the horn. The pressure from the woofers won't be felt by the mid bass and vice versa. I can tell you from practical experience that there is NO movement of the midbass drivers in a TQWT or DTQWT (I have both concepts). I also have back loaded horn speakers (so compression chamber/exponential expansion) that have the same lack of movement (never more than about 1mm movement for any of these speakers regardless of bass). The woofers on my Hornings do not "puff out" the Lowther on the front...it simply doesn't move. He simply drove the 8008 beyond it's limits...he doesn't say how it actually happened.

 

[D.Duttilleux]

That can't be quite right because the air will move to the region of lower pressure...ie. the mouth of the horn. The pressure from the woofers won't be felt by the mid bass and vice versa. I can tell you from practical experience that there is NO movement of the midbass drivers in a TQWT or DTQWT (I have both concepts). I also have back loaded horn speakers (so compression chamber/exponential expansion) that have the same lack of movement (never more than about 1mm movement for any of these speakers regardless of bass). The woofers on my Hornings do not "puff out" the Lowther on the front...it simply doesn't move. He simply drove the 8008 beyond it's limits...he doesn't say how it actually happened.

The pressure difference pulls the 8008 inwards and vice versa.
Troels explains the inner workings on his site.

No movement at all means no sound. The cones still move, although visibly less compared to other vented systems.

Although I can hardly detect any vibration from the woofers in my BR cabs either.

 

[morricab]

The pressure difference pulls the 8008 inwards and vice versa.
Troels explains the inner workings on his site.

No movement at all means no sound. The cones still move, although visibly less than in other ventilated systems.

His description misses out on the fact that when the woofer is moving inward to load the horn on that side the front driver is also moving inward electrically (they are wired in phase according to the crossover but are 180 degrees opposed). So, the driver on the front is moving inwards anyway thanks to the electrical signal. So, the mid/bass driver is also loading the horn at the same time thanks to the drive signal, not sucking from the woofer...all air will move to the mouth of the horn, which is at a lower pressure than drivers compressing the air.

I never said they don't move at all...I said they don't move visibly...big difference. My point is that at no time are the woofers on my Horning sucking in the Lowther on the front and making it move inward excessively, which would also distort and cause some kind of doppler effect from the woofer modulating the mid/bass.

 

[Audiohertz2]

Troels Gravesen
http://www.troelsgravesen.dk
DTQWT-212-mkIII

The 12" was made to play deeper, not louder. I cannot stress this enough because we inevitably regard a bigger speakers as one that should be able to play louder. This is not the case for the 12" version. The 10" version features a 40 Hz horn (check impedance curve) where the 12" version with its more than 3 meter long horn takes us down to 30 Hz. The 8008 front driver carries the full signal and is part of the speaker's bass performance. Thus, the 8008 front driver does not have a high-pass filter, which has indisputable advantages but also limits power handling. The OBL-11 speaker basically having the same drivers and crossover can play louder but requires expensive coupling capacitors for the middriver to perform the best. As always: Any speaker is a compromise between a set of design parametres.

Looks like all the drivers sharing the same chamber and port , very poor design ..!

 

[morricab]

Looks like all the drivers sharing the same chamber and port , very poor design ..!

It's not a port, its a horn. You have two paths of different lengths feeding the same mouth...it's actually a very good design and has excellent bass if designed with the right lengths of the two horns.

 

[morricab]

An explanation of the Horning (essentially the same DTQWT concept as the Troel Graveson concept)

Listening #38

The Hartleys I wrote about last month may be the loudspeaker drivers that time forgot, but the venerable Lowthers of Sidcup, England, reign supreme as the horseshoe crabs of the loudspeaker world: strange, ungainly things that have scarcely changed since the days when Franz Schmidt and Robert...

www.stereophile.com

 

[D.Duttilleux]

Troels:

Basic principles of DTQWT:
DTQWT is in principle a 2-way with integrated subwoofers, thus no high-pass filter on the main front driver. This has the indisputable advantage of not needing any series capacitors, which would be excessively expensive if of good quality and sonically inferior to no caps, no matter how good the caps are.
Loading a horn helps keeping front driver membrane in place due to high acoustic impedance compared to a vented enclosure or open baffle and this is further assisted by the mode of action of all drivers.
DTQWT features an 8" front driver and two 10" rear mounted drivers, all connected with positive polarity. They are placed opposite to one another and the rear drivers are fed through a huge coil, thus only adding weight to the lower octaves. All drivers load a center horn and you may ask whether the large bass drivers won't have an impact on the front driver from sharing the same center horn and the answer is yes - and this is intentional. Air goes where pressure is low, thus when the rear bass drivers move inwards, they will push air into the large center horn and by doing so they will suck air from the front horn and pull in the membrane of the front driver. Obviously the front driver will do the same thing for the bass drivers.
By fine-tuning expansion of front, center and rear horns while measuring impedance, a balance can be found allowing the best possible power handling of the main front driver. The subjective experience from this is a cleaner midrange, distortion has been lowered (see measurements below) at high SPLs and yes - we have more bass. In fact a lot more bass compared to TQWT. The typical quality of the bass from a horn is quite different from conventional high mass/low efficiency bass drivers in small vented enclosures. The DTQWT delivers deep, dynamic and dry bass without the typical vented enclosure overhang.
In principle we can load the horn with any 10" bass drivers regardless of Fs, but there are limits. I found drivers with Fs ranging from 30-60 Hz suitable and without any noticeable difference unless the driver at the same time has high Fs and extremely low Qt, e.g. Faital 10PR300, which on paper looked suitable but in reality didn't perform well. Actually Fs was closer to 65 Hz and Qt = 26. The Eminence Deltalite 2510 II proved just ideal with Fs = 49 Hz and Qt = 0.39 (own data).
The length of the horn determines the lowest frequences you can expect from these kind of systems. This is not a function of the driver's Fs as many may think. Mind you: You can have a 5" high-Fs driver doing 30 Hz; you only have to built a humongous exponential horn to make it happen.
DTQWT is designed to do 40 Hz and from the impedance graphs below you can see this is the tuning frequency of the horn making two impedance peaks like a vented system.

 

[morricab]

Troels:

Basic principles of DTQWT:
DTQWT is in principle a 2-way with integrated subwoofers, thus no high-pass filter on the main front driver. This has the indisputable advantage of not needing any series capacitors, which would be excessively expensive if of good quality and sonically inferior to no caps, no matter how good the caps are.
Loading a horn helps keeping front driver membrane in place due to high acoustic impedance compared to a vented enclosure or open baffle and this is further assisted by the mode of action of all drivers.
DTQWT features an 8" front driver and two 10" rear mounted drivers, all connected with positive polarity. They are placed opposite to one another and the rear drivers are fed through a huge coil, thus only adding weight to the lower octaves. All drivers load a center horn and you may ask whether the large bass drivers won't have an impact on the front driver from sharing the same center horn and the answer is yes - and this is intentional. Air goes where pressure is low, thus when the rear bass drivers move inwards, they will push air into the large center horn and by doing so they will suck air from the front horn and pull in the membrane of the front driver. Obviously the front driver will do the same thing for the bass drivers.
By fine-tuning expansion of front, center and rear horns while measuring impedance, a balance can be found allowing the best possible power handling of the main front driver. The subjective experience from this is a cleaner midrange, distortion has been lowered (see measurements below) at high SPLs and yes - we have more bass. In fact a lot more bass compared to TQWT. The typical quality of the bass from a horn is quite different from conventional high mass/low efficiency bass drivers in small vented enclosures. The DTQWT delivers deep, dynamic and dry bass without the typical vented enclosure overhang.
In principle we can load the horn with any 10" bass drivers regardless of Fs, but there are limits. I found drivers with Fs ranging from 30-60 Hz suitable and without any noticeable difference unless the driver at the same time has high Fs and extremely low Qt, e.g. Faital 10PR300, which on paper looked suitable but in reality didn't perform well. Actually Fs was closer to 65 Hz and Qt = 26. The Eminence Deltalite 2510 II proved just ideal with Fs = 49 Hz and Qt = 0.39 (own data).
The length of the horn determines the lowest frequences you can expect from these kind of systems. This is not a function of the driver's Fs as many may think. Mind you: You can have a 5" high-Fs driver doing 30 Hz; you only have to built a humongous exponential horn to make it happen.
DTQWT is designed to do 40 Hz and from the impedance graphs below you can see this is the tuning frequency of the horn making two impedance peaks like a vented system.

Yes, I know what he wrote. I don't agree with the sucking membrane part. I think this is incorrect.

 

[D.Duttilleux]

Looks like all the drivers sharing the same chamber and port , very poor design ..!

No it's not a poor design. It's actually quite clever.

Years ago, I was tempted to buy a professionally carpented pair that were offered for around €600.

 

[D.Duttilleux]

Yes, I know what he wrote. I don't agree with the sucking membrane part. I think this is incorrect.

Perhaps polarity is different in your system?

 

[Lagonda]

Well if good sound is not your top priority...

Most of the NOS tubes these days are fake anyway !

 

[Audiohertz2]

It's not a port, its a horn. You have two paths of different lengths feeding the same mouth...it's actually a very good design and has excellent bass if designed with the right lengths of the two horns.

So let me get this straight its not a port , looks like a horn loaded port to me and no its a disaster to have 3 drivers coupling a port differently its easily seen in the impedance /phase plot and sure in the FR too , cant imagine the noise too ..

So no its a poor design ..!

 

[Audiohertz2]

No it's not a poor design. It's actually quite clever.

Years ago, I was tempted to buy a professionally carpented pair that were offered for around €600.

I don't find it clever at all , please post his impedance curves with all the resonance ripples bumps and valleys ..

 

[morricab]

So let me get this straight its not a port , looks like a horn loaded port to me and no its a disaster to have 3 drivers coupling a port differently its easily seen in the impedance /phase plot and sure in the FR too , cant imagine the noise too ..

So no its a poor design ..!

Frequency response, phase etc are all there on Troels website...no need to guess about it.

 

[D.Duttilleux]

An explanation of the Horning (essentially the same DTQWT concept as the Troel Graveson concept)

Listening #38

The Hartleys I wrote about last month may be the loudspeaker drivers that time forgot, but the venerable Lowthers of Sidcup, England, reign supreme as the horseshoe crabs of the loudspeaker world: strange, ungainly things that have scarcely changed since the days when Franz Schmidt and Robert...

www.stereophile.com

I've read the Stereophile + the 6moons review and kinda like the concept, except for the Lowther perhaps. I know Lowthers are capable of stunning midrange, but they're far from ideal for my musical preferences.
However, during the reading I found myself contemplating a bigger version of a DTQWT with a compression driver + wg, 8 or perhaps 10" mid and 2x 15s on the back. Though that would require a fairly wide baffle, or an asymmetrical/trapezoidal shaped footprint, which would complicate the design and construction.

A major difference between Troels' DTQWT and the Hørning concerns the crossovers, or, in the latter case, lack thereof.
The impact on phase versus current/voltage alone makes a one-on-one comparison between both systems difficult.