I don't know how to answer this since I've never done it but I think it's totally unnecessary. I would keep it simple and put them in the same enclosure. Remember, when you tune them to have an F3 around 45Hz they still have a ton of energy below that and room gain will usually give you more so it actually works better in many rooms. If you're only listening at 85db then you'll be fine but if you like to go up to 100db then tune them a bit higher. You will still have an almost unreasonable amount of low distortion energy down into the low 30's. Most people think I have a subwoofer on but it's just the 4x Purifi woofers.
Based on your vast experience and knowledge, would you say a tuning of 32 Hz with a 55L enclosure would be suited for these 2 drivers? Would separate enclosures with different tuning work better? We are wondering how would you approach this and what would you change?
I see. I will rethink the enclosure and redo some calculations. I installed Basta! and did some experimenting, response looks 99% similar to vituixcad. In addition It has a very interesting option caled "room gain" which simulates an in-room response, with which i'll play a bit. Thanks for the info!
terraxtxx you have a very interesting project in the plan, CAD, and obtain parts stage. I will offer three bits of advice at this stage.
- Regarding Viawave SRT7 tweeter. My experiments using chinese pure foil ribbon tweeters and GR Research's Neo 3 planar magnetic aluminum etched conductor on Kapton film tweeters yielded very good results. I would spend a few extra tens of euros on Viawave's GRT-145W-4 or -8 model to get the horn/wave guide. In my experience pure foil ribbons and AMTs struggle to get to the 1.5k-1.8k Hz crossover often suggested. It can be done with more complex higher parts count crossovers. I prefer 2nd order when possible. Note the GRT models' higher output circa 2k - 4k Hz that will yield less stress on the tweeter once crossed over. As good as the PTT6.5 drivers are physics ultimately applies, see https://hificompass.com/en/reviews/purifi-ptt65w08-01b-ptt65x08-nfa-01 and specifically this waterfall plot, we want the woofer rolled off before it gets to the breakups in the 4k - 5k region.
- On the enclosure size issue while weighting the advice given be aware the short and to the point suggestion in post 2620 by user irisbo. I call that to your attention in case you are not aware irisbo is Lars Risbo, Co-Founder, and CTO of Purifi, i.e. designer and project lead on the PTT6.5 drivers.
- If you have the capability to build two pairs simple (butt joints no or minimal finishing) test enclosures before committing to a fully detailed final box try both the larger and smaller sizes/tunings. I have tried both and each sets of compromises sounds very good with the differences being rather small in my experience until one really flogs the system with big power asking for 100+dB outputs. If like me most of your listening is in the 75-85 dB range the extra bass reach of the larger lower tunings is a great party trick. Personally I also find I am more likely to take the time to get the final enclosures build just right when I have quick-n-dirty prototypes playing in my system. Removes the temptation to rush just so I can hear the drivers.
Thank you!
1. I have past experience with Viawave tweeters, have been using them in various builds for some years (Viawave GRT-145-4 and SRT-7). I usually tend to avoid the waveguide design since it ads a certain complexity to the off-axis response and how it mixes with the midrange. My philosophy is keep it as simple as possible, if possible. Even so, the Purifi Tweeter would be the crown jewel in this build...if it were available!
2. Of course I know who the legend Lars Risbo is. I am also aware of the SPK16 Reference Design that he mentioned. Planning to do more research in that direction, in the coming days, since it seems to be a very valuable source of knowledge and wisdom based on their very precious R&D. The only downside, for me at least, is that their reference design is based on using a PR and it includes only 1 woofer. I believe complex correlations have to be made for my specific design...
3. Was also thinking to experiment a bit with various enclosures before deciding on the final size / tuning, but I wanted to first talk to you fellow DIY-ers and learn from your experience, prior to starting this beautiful journey with the new - for me at least - Purifi amazing drivers.
Room gain is somewhat important but naturally varies. I find that the most important parameter to look at id the maximum SPL. This shows that you can go down to 30Hz but might only get 90db of it while you can get 105db at 40Hz. Playing with port size and length really varies this along with enclosure size. It can be quite interesting and has really helped me decide which woofers to use and how to use them because I generally like to make things loud at least for a short time. Cheers and happy building.
Sorry to jump in on his, but we are completing a speaker design ( 4 total) similar to the Purifi prototype with a single 6.5" Purifi (paper cone) and two of the Purifi passive radiators, one on each side facing each other per speaker. In the past we have used No-Rez from GR Research on the inside surfaces of speakers and subwoofers we are building. Almost all of the previous speakers/woofers were sealed and we used Parts Express's acousta-stuf at about 1 pound per cubic foot. This produced excellent results IMHO. On the passive radiator design since the No Rez has roughly 3/4" of foam attached to it would that be enough damping for a passive radiator design or should I line the inside with more insulation? Thanks for any input!
For Directiva, I used the .75 inch Sonic Barrier and Acousta-stuf. Sonic Barrier was likely overkill for a smaller cabinet. Have used No-Rez too but takes a lot of internal volume and is pricey. I also own the Purifi SPK5 and it did not call for any panel dampening but has a diagonal brace to break up the larger panel modes. It does use significant cotton-based damping material.
If your cabinet does not have major bracing, might want to use some vinyl damping sheets on longer panels. Otherwise, would just use Acousta-Stuf internally to help with box modes. Would measure the passive radiators in nearfield to determine how much damping is optimal. This is the approach I take currently as it allows more flexibility, and lower cost than stick-on combo products like No-Rez.
Hope this helps!
If your cabinet does not have major bracing, might want to use some vinyl damping sheets on longer panels. Otherwise, would just use Acousta-Stuf internally to help with box modes. Would measure the passive radiators in nearfield to determine how much damping is optimal. This is the approach I take currently as it allows more flexibility, and lower cost than stick-on combo products like No-Rez.
Hope this helps!
Purifi goes mass market 🤩
https://www.hifiklubben.se/radiant-...89296-5dfd-40c2-b5a7-b8b7e3342984&storeId=621
https://www.hifiklubben.se/radiant-...89296-5dfd-40c2-b5a7-b8b7e3342984&storeId=621
Purifi goes mass market = Radiant Acoustics
The international facing direct to consumer site:
https://radiantacoustics.com/
Model is called Clarity 6.2 offered at 3,998 euros pair including shipping. Or for europeans from the 150 HiFi Klubben retail stores.
At the level we like to deep dive on diyAudio this promotional video "Behind Radiant Acoustics: Clarity 6.2 | Innovative Technologies & Craftsmanship"
goes into both the technology and teamwork among Peter Lyngdorf's holdings that resulted in the Clarity 6.2.
I also enjoy Stjernholm Reviews YouTube reviews for the info and irreverent humor, here is part one of their review. "HIGH-END on the CHEAP! Radiant Acoustics Clarity 6.2 - FULL REVIEW! PART 1"
Also respect to Stjernholm Reviews for pushing devices under test until the drivers hit their stops, I wonder how many tweeters they loose?
For those of us who are long time followers of this diyAudio thread I can't help notice how the Clarity 6.2 size and configuration follows advice Lars Risbo – Co-Founder & CTO, PURIFI has shared here.
The international facing direct to consumer site:
https://radiantacoustics.com/
Model is called Clarity 6.2 offered at 3,998 euros pair including shipping. Or for europeans from the 150 HiFi Klubben retail stores.
At the level we like to deep dive on diyAudio this promotional video "Behind Radiant Acoustics: Clarity 6.2 | Innovative Technologies & Craftsmanship"
I also enjoy Stjernholm Reviews YouTube reviews for the info and irreverent humor, here is part one of their review. "HIGH-END on the CHEAP! Radiant Acoustics Clarity 6.2 - FULL REVIEW! PART 1"
For those of us who are long time followers of this diyAudio thread I can't help notice how the Clarity 6.2 size and configuration follows advice Lars Risbo – Co-Founder & CTO, PURIFI has shared here.
It is an interesting example of similar design goals leading to similar designs comparing the Clarify 6.2 to my design introduced in June 2023 as the PureArtFi LS-6. PureArtFi
Both use:
Our PureArtFi LS-6 is considerably upmarket compared to the Clarity 6.2. PureArtFi featuring master craftsman built enclosures and stands in solid hardwoods and shop sawn veneers. Speaker designers here on diyAudio will spot the LS-6s' enclosures is considerably larger. Much of that volume is used for the interior features. Sub enclosures are used to pot and damp the crossovers, others hold compacted sand acting as loose mass dampers and a large rear chamber for tweeter. All the interior sub enclosures also act to divide interior space into complex non-parallel volumes.
Both use:
- Paper cone PTT6.5 series woofer and pair of matching PRs.
- Tweeter in horn/waveguide. Radiant an AMT, PureArtFi a planer type.
- Squared off styling with baffle front edges chamfered.
Our PureArtFi LS-6 is considerably upmarket compared to the Clarity 6.2. PureArtFi featuring master craftsman built enclosures and stands in solid hardwoods and shop sawn veneers. Speaker designers here on diyAudio will spot the LS-6s' enclosures is considerably larger. Much of that volume is used for the interior features. Sub enclosures are used to pot and damp the crossovers, others hold compacted sand acting as loose mass dampers and a large rear chamber for tweeter. All the interior sub enclosures also act to divide interior space into complex non-parallel volumes.
Amplifiers! I'm drawn to the promise of Purifi low distortion but I love my Pass/Aska Class A 25W-ers. I have a small room, I don't listen loud, but my gut says that driving PTT6.5X04's in a small box with anything less than an arc welder could be risky.
Has anyone tried living with such a combo?
Has anyone tried living with such a combo?
A very good speaker using a Purifi has been around … though not afaik not promoted for a couple of years
very similar price to the new speaker from Radiant. Looking forward to seeing how the ribbon & waveguide performs
https://www.erinsaudiocorner.com/loudspeakers/march_audio_sointuva/
just use a dB calculator. Which of course factors in watts, sensitivity and listening distance. some also factor in reinforcement from placement near a wall
Hi Simon,
While the sensitivity of a typical Purifi woofer based speaker seems to point to high power amps I have a couple of experiences that lower power high quality power amps can work very well indeed.
First on the tube side at this years Lone Star Audio Fest my demo room used the Miller Audio Dyna-70 tube amp. The Dyna-70 is a new production version of the classic Dynaco 70, like that amp its rated 35 wpc. The Miller Audio version does have larger capacity power transformer and uses solid state diodes for B+. These are 'jumbo' tube watts. Playing into the PureArtFi LS-6 (PTT6.5 woofer & PRs) or other times the Audio Crafters Guild Pure 70 (PTT5.25 woofer & PRs) I was very pleased with the quantity and quality of sound produced.
A second data point is I was lent by my friend Tony Crocker of Swan Song Audio his prototypes for a LiPoly battery packs powered mono blocks to try at home with the LS-6s. Tony lists the specs and features of these as:
Battery powered
- 11 watts current limited
- 4 gain levels. No volume control
- Adjustable 1st stage transistor power supply for 1 watt and under listening
- Melf resistors vs thick film
- Resin and polymer tantalum caps
- Hand matched transistors
- Wattage meter
- TFT display
- Copper heat sinks
As seen in the closeup my usual amps are ACG 1000 series based on 500 wpc ICEpower modules. The blue 3D printed cases of the Swan Song amps placed on top for the loan.
Of course both of the lower power amps cannot play in the 90-100+ dB range my usual amps go. And at LSAF the hotel room small listening space helps. My home space is a large great room with 12 foot ceilings, both smaller power amps worked well there. What allows me such good results with purity-over-power amp designs is my typical listening levels are mid 70s to 80s dBs.
@Norman Tracy thank you for some useful information, good to hear. I think you just cost me a significant sum of money!
Review/measurements for Radiant Acoustics 6.2 are up, thanks to @bikinpunk
@Norman Tracy
Amazing built-to-last-forever old-world charm with your PureArtFi LS-6
Wishing you all the best with your venture
@simon dart
If you need a bit more voltage sensitivity you can choose the W model
@Norman Tracy
Amazing built-to-last-forever old-world charm with your PureArtFi LS-6
Wishing you all the best with your venture
@simon dart
If you need a bit more voltage sensitivity you can choose the W model
Suggestions to try; from the website:
Eg.
From-
https://ptt.purifi-audio.com/shop/p...,5210,5211,5212,5213,5214,5215,5216,5217,7591
Eg.
From-
https://ptt.purifi-audio.com/shop/p...,5210,5211,5212,5213,5214,5215,5216,5217,7591
Great question! Its a new alignment we invented giving an equi-ripple response with a selectable ripple in the pass band (typicall 0.5B is allowed). This gives a deeper bass extention and lower pass band group delay compared to QB3. I am writing an article for Voice Coil about it to appear in the Dcemeber issue. It is also applicable for passive radiator boxes as we show. Note that I made some updates to the algorithm and we have a pending update of the box suggestions in the web shop