I'm new to this and could use some help. I am in the process of ordering parts to build a 300b SET amplifier, and I need a pair of efficient speakers to go with it. I'm thinking it may be fun to build the speakers as well. Would anyone like to help me choose drivers, find a cab design, and help with crossover design? I want to build smaller bookshelf speakers on stands and I'd like to stay under $500 for this project. I was originally thinking 2-way speakers but I'm not opposed to a single full-range. Obviously I want the best sound quality and highest efficiency that I can achieve within my budget. I listen everything, classical, jazz, country, folk, bluegrass, rock, metal, hip-hop, etc. So I need the speakers to be versatile.
I'm trying to learn as much as I can about designing so if you have any must read links, I'd be happy to go read them. Thank you.
Jon R
I'm trying to learn as much as I can about designing so if you have any must read links, I'd be happy to go read them. Thank you.
Jon R
Do take note that a 300B SET will (almost surely) have a high output impedance, so you want a loudspeaker with flattish impedance response since the speaker impedance will affect the end frequency response.
Crossovers are the key factor in maintaining a flat impedance, which is why youoften find SET owners going to single driver speakers without XOs.
My feeling is that the impedance issue can often be more important than efficiency.
dave
Crossovers are the key factor in maintaining a flat impedance, which is why youoften find SET owners going to single driver speakers without XOs.
My feeling is that the impedance issue can often be more important than efficiency.
dave
Jon,
Do take note that a 300B SET will (almost surely) have a high output impedance, so you want a loudspeaker with flattish impedance response since the speaker impedance will affect the end frequency response.
Crossovers are the key factor in maintaining a flat impedance, which is why you often find SET owners going to single driver speakers without XOs.
My feeling is that the impedance issue can often be more important than efficiency.
dave
Do take note that a 300B SET will (almost surely) have a high output impedance, so you want a loudspeaker with flattish impedance response since the speaker impedance will affect the end frequency response.
Crossovers are the key factor in maintaining a flat impedance, which is why you often find SET owners going to single driver speakers without XOs.
My feeling is that the impedance issue can often be more important than efficiency.
dave
I plan on using a multi-tap output transformer with a 4ohm and an 8ohm output. So I should be able to use either 4ohm or 8ohm speakers.
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That has nothing to do with the output impedance (not directly anyway), that matches the very high impedance of the tubes to something much more resembling that required to drive the loudspeaker. This is to maximize power transfer.
Rout is something different. Unfortunately even the amp designers all to often do not know the answer to that question. At a guess your amp will have a 2-4Ω Rout. Most SS amps in contrast have Rout that is a fraction of an ohm. Damping, which is a bastardized version of the reciprocal of Rout is very often what the marketing guys specify.
The output impedance of your amp wil affect the performance and design of your loudspeakers. Here is an example to illustrate:
http://wodendesign.com/downloads/King-of-Swingers.pdf
You can see that even the difference between my lowest and highest guess is significant. One can cur and build multiple boxes, but knowing what the Rout is would save a lot of effort. BTW, these would be a decent, simple choice for your amplifier. The A10p has been a favourite of SET owners.
Do note that there are very few loudspeakers that are 4 or 8Ω, very very few. There is a big(ish) peak at resonance, and often a rising impedance as frequency goes up (copper pole pieces help minimize that [look for the specified inductance to get an idea]) and XOs all to often cause a big peak near the XO frequency.
dave
Rout is something different. Unfortunately even the amp designers all to often do not know the answer to that question. At a guess your amp will have a 2-4Ω Rout. Most SS amps in contrast have Rout that is a fraction of an ohm. Damping, which is a bastardized version of the reciprocal of Rout is very often what the marketing guys specify.
The output impedance of your amp wil affect the performance and design of your loudspeakers. Here is an example to illustrate:
http://wodendesign.com/downloads/King-of-Swingers.pdf
You can see that even the difference between my lowest and highest guess is significant. One can cur and build multiple boxes, but knowing what the Rout is would save a lot of effort. BTW, these would be a decent, simple choice for your amplifier. The A10p has been a favourite of SET owners.
Do note that there are very few loudspeakers that are 4 or 8Ω, very very few. There is a big(ish) peak at resonance, and often a rising impedance as frequency goes up (copper pole pieces help minimize that [look for the specified inductance to get an idea]) and XOs all to often cause a big peak near the XO frequency.
dave
Thank you for the info. What about the Tang Band drivers? Also, I'm not opposed to floor standing as long as I can keep them sleek and not too terribly deep. So far I'm looking at the following:
Mark Audio Alpair 10P
Tang Band W6-1916 (assuming I can find them as they are discontinued)
Tang Band W6-2144
Tang Band W8-1772
Tang Band W8-1808
Mark Audio Alpair 10P
Tang Band W6-1916 (assuming I can find them as they are discontinued)
Tang Band W6-2144
Tang Band W8-1772
Tang Band W8-1808
Of the drivers i have had experience with the A10p is better IMO than the T8-1772 or 1808. And less money. And more boxes to choose from.
dave
dave
Thanks for your help! From what I've read the A10p is more suited to what I'm trying to do. Doesn't hurt that they are cheaper too! Now I need to decide on a box for the drivers. I'm still going through the amplifier schematics and making sure I understand them while I compile a BOM. Hoping to start buying components and building soon.
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Search and you will find many. Scott has a simple reflex and i can provide more complex ones with some benefits. There are others, many do not fall into the bookshelf class (Frugel-Horn XL, Pensil10p for instance).
dave
dave
-first thing that "popped" into my head was:
efficient & small (stand mount) = no bass.
Needs powered subwoofer.
Second thing after reading through replies is:
MA 10P measures broken.
Good enough non-linear above 1 kHz, but it's linear behavior above 1kHz is charitably: poor.
Lousy non-linear below 1 kHz, but it's linear behavior is good enough.
That's a no-win situation.
Plus, it's not particularly efficient.
MarkAudio Alpair-10P | HiFiCompass
I realize that Planet10 is all about the subjective result, but this time I don't think it overcomes very clear negatives (both measurable and with respect to stated goals). IF it was just about measurable objective - there is the 10M ..but it's a bit less efficient.
efficient & small (stand mount) = no bass.
Needs powered subwoofer.
Second thing after reading through replies is:
MA 10P measures broken.
Good enough non-linear above 1 kHz, but it's linear behavior above 1kHz is charitably: poor.
Lousy non-linear below 1 kHz, but it's linear behavior is good enough.
That's a no-win situation.
Plus, it's not particularly efficient.
MarkAudio Alpair-10P | HiFiCompass
I realize that Planet10 is all about the subjective result, but this time I don't think it overcomes very clear negatives (both measurable and with respect to stated goals). IF it was just about measurable objective - there is the 10M ..but it's a bit less efficient.
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A pretty weak generalization.
Have you ever heard the Alpair 10p? Definitely not broken. I have heard many well measuring speakers tha sound broken. 90dB sensitivity. And a lot of very happt SET owners using them. Any measurement using a low output impedance amplifier will not tell the real story.
dave
dave
@planet10
I wondered if you got my email about the guy to make enclosure kits in Toronto? Any interest?
I couldn't convince my brother to take those Aikos off your hands unfortunately [sigh]
I wondered if you got my email about the guy to make enclosure kits in Toronto? Any interest?
I couldn't convince my brother to take those Aikos off your hands unfortunately [sigh]
Weak GENERALIZATION! 🙄
Have you forgotten Hoffman's Iron Law?
I don't think you have. 😉
Is it weak to generalize that 89 db average BEFORE any baffle-step compensation is most certainly not what any loudspeaker designer worth a dump would call EFFICIENT?
Hey, I'm not saying the 10P doesn't sound good - but it doesn't meet the requirements of efficient under any reasonable measure, and it doesn't measure well (at all) when there are other offerings that do: including the 10P.
I did, but sorry haven’t gotten to it yet. I have only talked with you about kits in TO. You did get my 1st reply.
dave
Of course i have. But there is also what one would consider bass.
90 dB measured. And BSC is a can of worms that is very situation dependent. Any propping up of the on-axis ontroduces an overlarge room response. I very rarely find need for explicit BSC other than taking care with room placement etc, and certainly have never found a need for it with the A10p. By its very nature a SET amp used with any speaker that has a rise at the resonance (ie almost all of them) could be considered a form of BSC.
But for many who seem to enjoy too much bass it is fine.
dave
My quest for a very efficient two-way led me to a MTM configuration using two PHL Audio 1240 6.5" woofers with 16 ohms impedance each with an Aurum Cantus G2 ribbon tweeter. The woofers have individually 92 to 93 dB rated SPL so add 6 dB for an 8 ohms impedance with a parallel connection. That makes the woofers in the 98 to 99 dB SPL range. The G2 is spec'ed at 96 dB SPL at 8 ohms. I ran my MTMs with an active crossover thou a passive crossover could be used.
When new these drivers cost in the $750 to $800 range but you might look for these drivers used to make your cost budget.
When new these drivers cost in the $750 to $800 range but you might look for these drivers used to make your cost budget.
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^
Yup, 96db as a full-bandwidth average is starting into what a designer would call "efficient".
(..89 db is only slightly above average when compared to most loudspeaker designs (..as J.A. as mentioned numerous times in Stereophile when talking about each loudspeakers measured sensitivity).)
16 ohm drivers in parallel is exactly the sort of thing that helps with the final result, particularly when factoring legitimate baffle-step compensation (..that doesn't require modal contribution, floor placement, etc.)
Yup, 96db as a full-bandwidth average is starting into what a designer would call "efficient".
(..89 db is only slightly above average when compared to most loudspeaker designs (..as J.A. as mentioned numerous times in Stereophile when talking about each loudspeakers measured sensitivity).)
16 ohm drivers in parallel is exactly the sort of thing that helps with the final result, particularly when factoring legitimate baffle-step compensation (..that doesn't require modal contribution, floor placement, etc.)
For over 80 years.... Tubes + horn tweeter + 12" midbass + big ported box == MUSIC
You are not putting these speakers on a shelf or on a desk.
You plan to put these speakers on a stand... why not just build a floorstanding speaker?
If you can accept a larger cabinet.... W=16", H=25" or floorstanding, D=9.75"
I can post the EconoWave crossover schematic....
Parts Express USA
$13 B-52 PHRN-1014 1" Horn 10" x 14" Bolt-On waveguide
Model: PHRN-1014|Part # 299-2303
$63 Peerless 1" exit DFM-2544R00-08 compression driver (1.75" dome)
$140 Eminence 12" Delta Pro12A Midrange
$50 crossover
OR... for $268 you can get a complete kit with CNC flat pack cabinet from
Denovo Audio HT-12
HT-12 econowave = $216.90 with CNC cut front baffle. $268 for complete CNC cut cabinet.
1 - Denovo 12" woofer made by Eminence: $75
1 - Celestion CDX1-1445: $45
1 - Denovo SEOS-15 waveguide: $35
1 - Set of crossover parts: $34.02
2 - Ports: $7.80
1 - CNC cut front baffle: $15
1 - Set of screws and gaskets: $1.50
You are not putting these speakers on a shelf or on a desk.
You plan to put these speakers on a stand... why not just build a floorstanding speaker?
If you can accept a larger cabinet.... W=16", H=25" or floorstanding, D=9.75"
I can post the EconoWave crossover schematic....
Parts Express USA
$13 B-52 PHRN-1014 1" Horn 10" x 14" Bolt-On waveguide
Model: PHRN-1014|Part # 299-2303
$63 Peerless 1" exit DFM-2544R00-08 compression driver (1.75" dome)
$140 Eminence 12" Delta Pro12A Midrange
$50 crossover
OR... for $268 you can get a complete kit with CNC flat pack cabinet from
Denovo Audio HT-12
HT-12 econowave = $216.90 with CNC cut front baffle. $268 for complete CNC cut cabinet.
1 - Denovo 12" woofer made by Eminence: $75
1 - Celestion CDX1-1445: $45
1 - Denovo SEOS-15 waveguide: $35
1 - Set of crossover parts: $34.02
2 - Ports: $7.80
1 - CNC cut front baffle: $15
1 - Set of screws and gaskets: $1.50
Attachments
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This is the amp I am planning on building. I'm currently waiting on a quote for the custom transformers, and sourcing the other components. I'm not looking for huge volume, I'm looking for beautiful music. That said, I'm very new to this stuff. I'm trying to learn as much as possible before pulling the trigger and purchasing parts. I am starting to lean towards floor standing speakers. For the moment I'm thinking the A10p in the FHXL. I plan on paring the amp with a NAD C368 and a turntable that I haven't decided on yet ($300-400 range). I'm not set on the speakers yet, I have time while research and build to keep contemplating. I do like the minimalistic look of a single full range driver, but my focus is quality music. What do you think of pairing this amp with the A10p's in the FHXL?
300B - Google Drive
YouTube
300B - Google Drive
YouTube
How big is the box and how low does it go. It is not immune to Hoffman’s Iron Law.
90 dB. With a pretty flat impedance curve.
Jim, what does the impedance of your speaker look like?
Also, is it 93 dB efficient (1w 1m) or 93dB sensitive (2.83 V in)? I can’t find any specification (only a coax w that number). If it is the 1st, that makes them 90 dB sensitive.
dave