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Tube amp speakers?
in DIY
I'm not a tube amp guy, so I'm looking for your ideas and recommendations for a friend of mine. He has a 1.8 to 6 watt Grommes PHI-26 single ended integrated amp and needs some speakers to fill a 11x12 room.
No subwoofer, book shelf size. What sensitivity do I need to target? Probably get some room loading and use 3 dB baffle step.
John H, btw forum has decided I don't get emails
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These have been used running full with a hp on a tweeter.
https://www.madisoundspeakerstore.com/approx-10-woofers/seas-prestige-a26re4-h1411-10-paper-cone-woofer/
not inexpensive- but a place to start
If he wants to run in in triode mode, it'll have to be something with decent sensitivity. I wa some Axiom bookshelf speakers when I was building 2A3 amps (1.5W). The manufacturer rated them at 89dB/W and that was more than loud enough for me most of the time in about the same size room.
But...I can't find any info on the intended output impedance for that amp. It only has one set of banana jacks, but there may be a switch or jumper inside to select a second tap on the output transformer.
It depends much on how loudly they will be expected to play. I usually run a 95 db/watt speaker with a headphone amp (300mW per channel) and they will easily play loud enough for critical listening. I can also turn them up enough to listen from other rooms with no issues. I have run my 88 db/watt bookshelf speakers with this same amp and they will play just fine for normal listening but they are not going to play rock music anywhere near concert levels.
This was all that I saw http://glowinthedarkaudio.com/grommes-phi26.html
Wow John, that's a tough one. Bookshelf size, high sensitivity and no subwoofer. The critical question to me is how big of a bookshelf. Could he do 1 ft3 or maybe even 1.5 ft3? Also, 8ohm only?
Ed yeah, I don't know that yet. It's got to "fit" in the room so size is an issue. Without knowing the amp details I'm assuming I need to keep the impedance above 6 ohms.
Can tube amps control a woofer at low frequencies? I'd like to target something with an f3 of 40 something.
It depends on the design of the amp, but FWIK damping factor is usually not great on tube amps.
That's what I thought.
If you come up with an easy to build project that's under say $300 in parts, I think lots of low power tube amp people would be interested. Just look at some of the speakers Decware has come up with. Their DM945 is $1400 and uses a Silver Flute 8" woofer. Given the sensitivity rating they claim, there's no baffle step in those.
https://www.decware.com/newsite/DM945.html
Holy crap no cross over. OK sounds like I've got some work to do.
The bass performance of a tube amp usually varies depending on the choice of output transformers. I'd suggest targeting more like 60 hz or higher. As stated by Hofmann's Iron Law, low bass, small enclosure, and high efficiency do not go together...
It's amazing what some die hard tube fans will put up with when it comes to speakers. Full range drivers with no real low end, beaming like crazy. That's why if you come up with a nice design, I think people would be interested. Even better if you could use drivers PE carries - they could make it a kit.
That will be my next amp purchase.
https://www.jfcomponents.com/
Brad which amp?
I don’t know. I haven’t got that far yet. I just know that I have way too many other amplifiers and no tube amplifiers..
https://www.jfcomponents.com/
Right now maybe the Faital Pro 6FE100 in 15 liters, F3 of 51hz, passive assist to help with the baffle step. Lots of tweeter options probably the SB29RDNC idk. Maybe 89 dB at 1K.
You have probably seen these, but one possibility would be to order the plans to build a pair of one of the below linked speakers. They are small two way's using the cheapy Peerless OC25SC65-04 tweeter and various cheap woofers (SB Acoustics SB17NRX2C35-4, Mark Audio Alpair 5.3 ). You would need a 3D printer, however, to print the horn. I think these speakers would be perfect for the small tube amp that you described. He has youtube videos for some of these speakers too, showing lots of squiggles and distortion charts. I'm not a horn speaker guy, but some people claim that modern day horns with the proper flare rate actually sound better with less distortion, etc.
https://josephcrowe.com/products/speaker-system-no-2037-6-5-2-way
https://josephcrowe.com/products/speaker-system-no-1900?pr_prod_strat=e5_desc&pr_rec_id=b7a2c2515&pr_rec_pid=6823191511124&pr_ref_pid=6832619290708&pr_seq=uniform
Not sure how well the Faital Pro measure I do have some neo Wavecor tweeters if I can get to 2- 2.5K
Maybe i missed it.? Why don’t you want baffle step?
https://www.jfcomponents.com/
They can’t get any hotter than these?
https://www.jfcomponents.com/
I should take an idle temp of the Dreadnaught
We're using 1.5 watts of power and want about 88- 90 dB. I think there needs to be some baffle step (3 dB) but we don't want to kill the sensitivity. I'm planning on getting some wall or corner loading to pick up the bottom end.
A 12- 15 inch in 3 cu ft isn't going to look right in the small space.
Bill that impedance looks pretty low.
Good catch. Looks like that idea is out.
https://www.speakerdesignworks.com/singularities
This could be a good match if you can commit to a tower.
Ken that's a good one. Not sure it will fit.
Current concept
Those SB 8" fullrangers are 92db/1w. They want over 1cf ported if an F3 below mid 50s is desired. That is a relatively small room though, so 1cf might do alright anyway bass-wise. Only $60 ea too. Mo money left for nice BSC parts.
If those look too pedestrian then the Tang Band W8-2145 looks much more snazzy and models pretty much identically from their specs in the same enclosure, but $160 ea. I have a pair but have yet to decide what to put them in. Tang band rates them at 90db/1w though
[EDIT]
IDK if it helps but I saw the PM220 is on sale:
https://parts-express.com/Dayton-Audio-PM220-8-8-Wideband-Midbass-Neo-Driver-295-345?quantity=1
Looks like I need to fit these speakers on a 12 inch high shelf. Here's the updated concept drawing