SET amp owners thread

[the sound of Tao]

A friend of mine added 4 subs. 2 x SVS 15s and a pair of 2x10" dayton in home made cabinets. Thats 4 x 10" drivers with a Krell KSA 250 driving them. plus the 15" SVS. 6 drivers total. Its impressive bass depth. Good pipe organ. But its also too much. To thick. To heavy. He claims world class performance.
I'm confused on Subs. Swarm makes sense. But its small drivers. Those small drivers seem to move a lot. You really hear the sub. Or maybe he has his bass all screwed up. I wrote to Pure Low. Way to expensive for me. Large cones are too much space. Horns are too large. I like fast bass. Slow deep bass is a turn off for me.
So then I circle around to biamping again. But the whole stink around active crossovers or even biamping and getting it to work raises its head.
The Ayre could run a pair of subs in a swarm. But I would rather have a mono behind each sub. I looked at Atmasphere. But 2 pair is a lot of $$ for me. I may reach out to Odyssey and see what they can do. If I could get monos for subs for $1000 a piece, that may work. I could get 2 and try to Biamp. If that did not do what I wanted and I went to a swarm. It would be a second pair of mono subs.

I get that OB sub isn’t like a more hard core deep sub approach but I think that’s why it might integrate better with OB mains. I’m not looking for overt box like sub extension either, more just a firm reinforcement down low to make things a shade more visceral or inject a touch more angularity in the character of the lower bass but still do flow and angularity the way the mid woofers do and still having a cohesive match in the immediacy of the OB midbass response characteristics.

When I was trying a Wilson Benesch Torus as an extension on the Maggie 20.7s I had a PS Audio BHK mosfet amp for the Torus and 250 watt EL34 Manley monos running in triode mode up on the 20.7s and was very much struck by what a great marriage was EL34 triode with MOSFET bass… much less perceptible a change in character than in using a Magtech as a transistor based SS amp for the Torus sub.

It may have just been luck to get such a good match but I do have a second identical LM805 amp to use with my main SET LM805 to try matching SET on the subs and then I also have a Kinki EX-M1+ here which is a 250 watt stereo mosfet amp I can use as compare SS amp for the OB subs to see how that integrates as it has a lithe character and a fairly taut and agile musical bass. Though Kinki monos might have worked on either side of the SET in terms of a better amp setout.

 

[morricab]

You should reconsider the calculation. In a normally furnished room, approximately 6dB of sound pressure is lost per meter of distance. If it is acoustically treated, significantly more
~10db means twice as loud or quiet for the human ear.

That has not been my experience. I have measured as little as 1dB loss (with large planars) at 3.5 meters but currently with my point source Hornings I am losing only about 3 dB at the listening position. Your numbers seem to be more theoretical rather than practical.

 

[morricab]

I would have thought maybe a SET amp built to the quality of your Blade amp with no holds barred premium tubes and Monolith Magnetics trafos would be a good direction to perhaps consider. That does sound a really interesting prospect to me at any rate. Maybe Triode Labs 2A3 SET might also be worth considering.

Also not sure on the rationale of circling back around for another try at SS after having a Dartzeel 108 and finding that not to be the solution for you. It’s good to have benchmarks to compare with but I’d doubt the Ayre would be a significantly different kind (or better) contender than was even the Dart you had.

That said maybe the upcoming First Watt Sit 5 monos might be worth considering with 40 Watt class A single ended SS… they could be worth waiting for if you want to try SS again but I still doubt that they’d be likely to offer more SET qualities than your Blade does already.

Agreed with your circling back comments. I would say that if you MUST go away from SET then a good push/pull Class A triode amp would still give a lot of the goodness with perhaps more control (this REALLY depends on the SET though).

The best SETs have both the beauty and the resolution/control but they are never inexpensive.

 

[Kingrex]

I get that OB sub isn’t like a more hard core deep sub approach but I think that’s why it might integrate better with OB mains. I’m not looking for overt box like sub extension either, more just a firm reinforcement down low to make things a shade more visceral or inject a touch more angularity in the character of the lower bass but still do flow and angularity the way the mid woofers do and still having a cohesive match in the immediacy of the OB midbass response characteristics.

When I was trying a Wilson Benesch Torus as an extension on the Maggie 20.7s I had a PS Audio BHK mosfet amp for the Torus and 250 watt EL34 Manley monos running in triode mode up on the 20.7s and was very much struck by what a great marriage was EL34 triode with MOSFET bass… much less perceptible a change in character than in using a Magtech as a transistor based SS amp for the Torus sub.

It may have just been luck to get such a good match but I do have a second identical LM805 amp to use with my main SET LM805 to try matching SET on the subs and then I also have a Kinki EX-M1+ here which is a 250 watt stereo mosfet amp I can use as compare SS amp for the OB subs to see how that integrates as it has a lithe character and a fairly taut and agile musical bass. Though Kinki monos might have worked on either side of the SET in terms of a better amp setout.

file:///C:/Users/KINGR/Downloads/U_and_H_Frames.pdf

interesting read. I think the H frame are interesting. They don't go to 20 hertz. But they perform solid at 30.

This thread direction should be in a dedicated thread. Is there a good thread on DIY subs?

 

[DasguteOhr]

That has not been my experience. I have measured as little as 1dB loss (with large planars) at 3.5 meters but currently with my point source Hornings I am losing only about 3 dB at the listening position. Your numbers seem to be more theoretical rather than practical.

Calibrate your microphone carefully. The most accurate is the Bruel&Kjarer system. Connect the microphone. 100 Hz/1 kHz/10 kHz test tones should always be 94 dB. Adjust the microphone and measure again.

 

[Atmasphere]

A friend of mine added 4 subs. 2 x SVS 15s and a pair of 2x10" dayton in home made cabinets. Thats 4 x 10" drivers with a Krell KSA 250 driving them. plus the 15" SVS. 6 drivers total. Its impressive bass depth. Good pipe organ. But its also too much. To thick. To heavy. He claims world class performance.
I'm confused on Subs. Swarm makes sense. But its small drivers. Those small drivers seem to move a lot. You really hear the sub. Or maybe he has his bass all screwed up. I wrote to Pure Low. Way to expensive for me. Large cones are too much space. Horns are too large. I like fast bass. Slow deep bass is a turn off for me.
So then I circle around to biamping again. But the whole stink around active crossovers or even biamping and getting it to work raises its head.
The Ayre could run a pair of subs in a swarm. But I would rather have a mono behind each sub. I looked at Atmasphere. But 2 pair is a lot of $$ for me. I may reach out to Odyssey and see what they can do. If I could get monos for subs for $1000 a piece, that may work. I could get 2 and try to Biamp. If that did not do what I wanted and I went to a swarm. It would be a second pair of mono subs.

My Swarm sub woofers really don't move that much. I have them facing the wall rather than open to the room so they are clearing within the room boundary effect. The bass isn't overpowering- its just right- no boom, no lack with great extension! When the LP calls for the room to shake, it does but if a string bass is the lowest instrument on the LP it just sounds like a bass (which I play).

In a room where standing waves are a problem using a Distributed Bass Array in this manner is really effective. You can use room correction (which includes bass traps) but that is only able to do about 5% of what's needed in the bass and if you have a bass null it won't be able to fix it.

 

[volken]

My amplifiers Telefunken AD1 and Telefunken AC2 driver design 1935 nothing special but very good combi with the Altec Model 17 .

 

[Kingrex]

My Swarm sub woofers really don't move that much. I have them facing the wall rather than open to the room so they are clearing within the room boundary effect. The bass isn't overpowering- its just right- no boom, no lack with great extension! When the LP calls for the room to shake, it does but if a string bass is the lowest instrument on the LP it just sounds like a bass (which I play).

In a room where standing waves are a problem using a Distributed Bass Array in this manner is really effective. You can use room correction (which includes bass traps) but that is only able to do about 5% of what's needed in the bass and if you have a bass null it won't be able to fix it.

Are your swarm 10" drivers in a ported cabinet with a sealing plug. The 12x12x20. Or do you use a larger driver

 

[Atmasphere]

Are your swarm 10" drivers in a ported cabinet with a sealing plug. The 12x12x20. Or do you use a larger driver

They are the Swarm subs, so 10" drivers in a ported cabinet as you describe. I wish I had started using them years earlier- they work so well!

 

[the sound of Tao]

file:///C:/Users/KINGR/Downloads/U_and_H_Frames.pdf

interesting read. I think the H frame are interesting. They don't go to 20 hertz. But they perform solid at 30.

This thread direction should be in a dedicated thread. Is there a good thread on DIY subs?

Thanks for that, there is some info out there. I read up on what I could find about 12 to 18 months ago. It’s a bit like horns, SET, open baffles… all niche but also tantalising.

Understanding on traditional approaches like box subs are way more available, more familiar, better researched and more evident everywhere… box based dynamic subs are more capable in reaching much deeper down into the subsonic. So impact is more overt and returns obvious. The reasons for them are legion… and yet the attraction to open baffle bass persists…

So if in bass quality I’m just chasing small changes rather than transformational ones and going open baffle subs is on my shortlist though in those fine ways the objective might just as easily be delivered through amp changes. Your thoughts on trying biamping is equally compelling… that’s been the loop for me slowing me down in moving forwards. A fairly simple choice between two quite interesting pathways

 

[Kingrex]

I feel like my Audion SET 845 adds a very pleasing knurl to lower piano notes. Makes me feel I have enough bass. Problem is I can hear the add. Its really pleasant. Its full. But in that add I loose a little speed and accuracy. Its not much. But its a little trade. Its a very little bit of poof on hot bass hits. The Blade cracks harder. More live and true to the instrument.
I wish I could find the lower register reach and push with the Blade on these open baffle while retaining the detail, speed and ability to clearly sort instruments. The more I listen to this Audion 845 the more I forget about the adds and losses. These are definitely one of the better amps I have had in my setup. They play well with the PAP.

FWIW I have about $1500 in tubes per mono block. With lesser 845 tubes the sound goes out the door. Elrogs are by far the best. The Psvane ACME might be good but I don't have them anymore to know. The Telefunken E88CC really step it up. The Siemens exaggerate the additive midrange. Bugle boy are not quite rigjt. Even the 7119 driver needs to be a well selected tube. I found a pair from a dealer in NYNY. I liked them so much I bought his more expensive D getter and actually like it less. So much for $ bringing sonic gains.

I fully admit, a big piece of the sorting is purely speaker placement.

Even so. I circle the idea, can I use the Blade and do something to get the lower registers to solidify. Is that a sub. Is that a biamp. Heck, what would happen with the 845 if I took that bass work away from it. I have this feeling it would be harder to find a amp to match the exagerstions the 845 adds in a biamp synerio. The Blade is far more linear and accurate. I think a SS amp of high speed would be more seamless with the Blade. Just a hunch. If I biamped with the 845, I would almost need a second 845.

 

[the sound of Tao]

Agreed with your circling back comments. I would say that if you MUST go away from SET then a good push/pull Class A triode amp would still give a lot of the goodness with perhaps more control (this REALLY depends on the SET though).

The best SETs have both the beauty and the resolution/control but they are never inexpensive.

This is the thing for me… we focus on improving the small things and in chasing them we sometimes sacrifice the big things.

That’s perhaps the developmental model of hifi in a nutshell for me.

We stand back and applaud night and day differences in areas in new models… and sometimes are we just more drawn to obvious changes. Music has tautness and it has plasticity… when does control become artificiality and actually just over damping.

If to get the appearance of resolution but the resultant sound becomes more like ether and less visceral then is that real resolution or just the immediate appearance of resolution. Like in trading out tone for a more easily distinguishable detail… I still use holistic summative distinctions as my guide, so a win in a criteria is only good if it leads to less ultimate distinctions between how the elements operate and just leads me something ultimately less artificial, more whole, more right and in ways ultimately for me more real.

With amplifiers I feel SET has become the foundation in amplification for me so I’m just unlikely at this point to trade it out to chase any one quality on its own. But that’s just my perception needs. So staying with SET and optimising for it is also where I’m at.

 

[acousticsguru]

Wow never seen pins that corroded , do you live near the ocean ..?

Not me, of course (see signature!), can't speak for the seller (tube is older than me, so…).

Greetings from Switzerland, David.

 

[Kingrex]

Each day I do a little to try and goose the performance of my Audion 845 setup. Today I pulled out my Akiko Corelli. I deoxed my cable ends and put the device into the power strip feeding my gear. This power strip is on the load side of my Torus. A few quick back and forth confirmed I heard nothing different. So I plugged it in and kicked back to just enjoy music.

About 15 songs later I'm very engaged. I'm thinking my stereo sounds more balanced. Less forward. Very detailed. I can easily hear details. Decay hangs. When the latest song ends I climb up to the speakers and put my head to the drivers. Its dead quiet. Just the faintest hiss. All the hum is gone. Hum I could hear at my seat. Non Is there now.

I hope it stays this way. I have been reading Steves thread on the Schnerzinger products doing the same. That is $12,000 in 2 boxes. And he bought a 3rd box thats probably more expensive. If I got the same verifiable result for $2,000, then I am very satisfied. All the fluff on air and space and speed are hard to validate. An elimination of hum and buzz is verifiable.

I guess it would be fair to say I have a $4250 Torus RM20 and a $2000 Akiko. So yes, proper power conditioning is not inexpensive. But when it works its a transformation in playback.

 

[Kingrex]

Gosh its spooky quiet. My room itself is very quiet. With the stereo hum now shut down I now hear the air filter downstairs. I am more aware other noises that make up the noise floor in the room. It also makes playback appear to be more (insert audiophile words). I think this is a simple function of less noise being reproduced by the drivers means less background distraction you may not be directly aware of. Buy your ears and mind are still processing it.

 

[the sound of Tao]

Each day I do a little to try and goose the performance of my Audion 845 setup. Today I pulled out my Akiko Corelli. I deoxed my cable ends and put the device into the power strip feeding my gear. This power strip is on the load side of my Torus. A few quick back and forth confirmed I heard nothing different. So I plugged it in and kicked back to just enjoy music.

About 15 songs later I'm very engaged. I'm thinking my stereo sounds more balanced. Less forward. Very detailed. I can easily hear details. Decay hangs. When the latest song ends I climb up to the speakers and put my head to the drivers. Its dead quiet. Just the faintest hiss. All the hum is gone. Hum I could hear at my seat. Non Is there now.

I hope it stays this way. I have been reading Steves thread on the Schnerzinger products doing the same. That is $12,000 in 2 boxes. And he bought a 3rd box thats probably more expensive. If I got the same verifiable result for $2,000, then I am very satisfied. All the fluff on air and space and speed are hard to validate. An elimination of hum and buzz is verifiable.

I guess it would be fair to say I have a $4250 Torus RM20 and a $2000 Akiko. So yes, proper power conditioning is not inexpensive. But when it works it’s a transformation in playback.

The Pureaudioprojects remind me very much of the Maggie 20.7s in the way they give such clear feedback on changes… much as good panels can be in this regard. I also find dialling them into their right point isn’t a small win but a real precision click into getting them right and whole (at last).

And for fear that Romy the Cat finds himself once again pontificating on video use and taking a few cheap shots questioning the mental health of others lol it would really be great to hear a few videos of your Pap trios on the Audion 845s and comparing them to your Blade amp to share some indications or sense of the different characters in comparison with the two amps on the Paps if you’re in for it.

 

[Kingrex]

I might try making a video. I always feel very unsatisfied with them. What would Carlos say I have a droid and its in a plastic case. I wonder if that affects the sound.

I don't have the Blades out. I put the Audion in as I had packed everything up to start the remodel, then it became haulted. The Audion were out in my rental and needed to be removed from that space. Instead of crating them back up, I had them brought over to the main house and up to my listening room. Kind of took care of 2 birds. And I don't need to open my preamp either as the Audion has a volume pot. That does not mean I won't ever be able to make a comparison. It's a bit of work and will make me move things around.

But I am liking the SET sound. I don't in any way sense I am lacking power of entering the relm of compression, artificial loudness because of distortion. Not at the volume levels I play at. At these levels, I actually sort of want to try a 2A3. There are a lot of them for sale on the used market in the $4 and less. Some looks interesting. The James Burgess or the Wavelength. Both on USAudiomart

 

[Atmasphere]

Understanding on traditional approaches like box subs are way more available, more familiar, better researched and more evident everywhere… box based dynamic subs are more capable in reaching much deeper down into the subsonic. So impact is more overt and returns obvious. The reasons for them are legion… and yet the attraction to open baffle bass persists…

Open baffle speakers have rear-firing output, which, if placed at least 5 feet from the wall behind them, can be used by the ear as echo-location information- so it makes images more palpable. If closer than that the rear firing information tends to be interpreted as harshness.

But open baffles really do have troubles making the bottom octave. So I'm of the opinion why bother? If the speakers are good to 50-60 Hz, you can use a Distributed Bass Array (using 4 subs) to handle the bass below that and there will be no worries getting them to blend as long as they don't have output above 80Hz (in most rooms) which can cause them to attract attention to themselves. This allows the open baffle speaker to be physically smaller.

The only catch is that the baffle is responsible for loading the woofer. Below the cutoff frequency defined by the baffle, the woofer just flops around. So its important to keep bass out of the speaker below its cutoff! For that you'll need an electronic crossover or the amp that handles the open baffle speakers can have smaller coupling caps inside, tailored to the desired cutoff frequency, which will have a side benefit of being a more transparent capacitor, and will certainly be helpful for any SET which has troubles with bass in the first place (prior discussion, search on 'elliptical load line').

In case you don't want to do the search, in a nutshell at low frequencies most SETs (excluding parafeed designs) the load line becomes elliptical due to a lack of inductance in the output transformer. The lower the frequency the more elliptical- and this behaves as a short to the tube, which isn't good for it. So if you can keep the load line at a frequency high enough where it really is a line, output power will be higher distortion will be lower and tube life longer.

 

[the sound of Tao]

… box based dynamic subs are more capable in reaching much deeper down into the subsonic. So impact is more overt and returns obvious. The reasons for them are legion… and yet the attraction to open baffle bass persists…

So if in bass quality I’m just chasing small changes rather than transformational ones and going open baffle subs is on my shortlist though in those fine ways the objective might just as easily be delivered through amp changes.

But open baffles really do have troubles making the bottom octave. So I'm of the opinion why bother? If the speakers are good to 50-60 Hz, you can use a Distributed Bass Array (using 4 subs) to handle the bass below that and there will be no worries getting them to blend as long as they don't have output above 80Hz (in most rooms) which can cause them to attract attention to themselves. This allows the open baffle speaker to be physically smaller.

The only catch is that the baffle is responsible for loading the woofer. Below the cutoff frequency defined by the baffle, the woofer just flops around. So its important to keep bass out of the speaker below its cutoff! For that you'll need an electronic crossover or the amp that handles the open baffle speakers can have smaller coupling caps inside, tailored to the desired cutoff frequency, which will have a side benefit of being a more transparent capacitor, and will certainly be helpful for any SET which has troubles with bass in the first place (prior discussion, search on 'elliptical load line').

In case you don't want to do the search, in a nutshell at low frequencies most SETs (excluding parafeed designs) the load line becomes elliptical due to a lack of inductance in the output transformer. The lower the frequency the more elliptical- and this behaves as a short to the tube, which isn't good for it. So if you can keep the load line at a frequency high enough where it really is a line, output power will be higher distortion will be lower and tube life longer.

Thanks for your thoughts Ralph. Both with the larger Maggie’s and now in the Pureaudioproject OB quintet horns the qualities of good planar or OB bass has become a clear baseline for me… one that I find completely compelling and the qualities of that bass is worth working within the constraints and extension limits.

While the functional limits are well known I find working within those limits of the type still fits my goals. Both with the Magnepan 20.7s and the larger Pap quintets (with 4 x 15 inch woofers a side) have sufficiently convincing reach in range to render concert grand with all the appropriate weight in the left hand has long been my base benchmark for usably sufficient bass extension to work for most of my music needs.

As I had mentioned I am just looking though for small incremental qualitative improvements rather than any transformational changes and I’m just going to explore (once again) if I can bring off integrating subs with panels without sacrificing what I value as the primary strengths of my setup in the process… in some ways it’s possibly as much curiosity as desire probably… I’ve even warned the cat to stay clear as old school curiosity has been known to occasionally be quite lethal to pussies… either way I’ve undertaken that no matter the outcome no boxes will be harmed in the making of these subs.

I figure that both OB and SET have their constraints and yet I’m happy to work within the limits of their paradigms and that determination strengthens more so with time and experience. To be honest men’s shed projects aside I’m fully content with where it’s at already… this part could just prove a learning experience and some explorative dipole woofer playtime. If it doesn’t ultimately work I’ll stick with what I have already so there’s no real great risk or loss involved in having a go and hopefully having some fun with it.

 

[Atmasphere]

Thanks for your thoughts Ralph. Both with the larger Maggie’s and now in the Pureaudioproject OB quintet horns the qualities of good planar or OB bass has become a clear baseline for me… one that I find completely compelling and the qualities of that bass is worth working within the constraints and extension limits.

While the functional limits are well known I find working within those limits of the type still fits my goals. Both with the Magnepan 20.7s and the larger Pap quintets (with 4 x 15 inch woofers a side) have sufficiently convincing reach in range to render concert grand with all the appropriate weight in the left hand has long been my base benchmark for usably sufficient bass extension to work for most of my music needs.

As I had mentioned I am just looking though for small incremental qualitative improvements rather than any transformational changes and I’m just going to explore (once again) if I can bring off integrating subs with panels without sacrificing what I value as the primary strengths of my setup in the process… in some ways it’s possibly as much curiosity as desire probably… I’ve even warned the cat to stay clear as old school curiosity has been known to occasionally be quite lethal to pussies… either way I’ve undertaken that no matter the outcome no boxes will be harmed in the making of these subs.

I figure that both OB and SET have their constraints and yet I’m happy to work within the limits of their paradigms and that determination strengthens more so with time and experience. To be honest men’s shed projects aside I’m fully content with where it’s at already… this part could just prove a learning experience and some explorative dipole woofer playtime. If it doesn’t ultimately work I’ll stick with what I have already so there’s no real great risk or loss involved in having a go and hopefully having some fun with it.

My recommendation is a set of Swarm subwoofers from Audiokinesis.

If the subs are crossed over such that there is significant output above 80Hz then you have to align them with your main speakers which can be a real pain.

The nice thing about the Swarm subs is they are designed to take advantage of the room boundary effect, which adds about +3dB/octave from 100Hz down. So the Swarms are designed to roll off at 3dB/octave over the same range; thus they are flat to 20Hz using a 10" woofer. I have mine with the drivers facing the wall so they are well inside the room boundary effect. Really helps with the WAF as well as being as out of the way as possible.