How to estimate sensitivity of a two way speaker

[Subbu68]

I saw on the net a two way OB kit from Monacor called Katana M1 https://www.monacor.com/products/components/speaker-technology/diy-/katana-m1

Individual speaker parameters are available from Monacor but not for this particular OB combo?

How to estimate the overall sensitivity? The kit is available from Amazon.de and perhaps some other EU based vendors. Before swiping the card have to make sure it won't sound anaemic with my SE amp that is 8W pc.

 

[keith_correa]

 

[arunkvivek]

I think Manzanita kit (open baffle) is far more sensitive.

 

[Subbu68]

View attachment 68624

Thanks a lot. Wonder why Monacor did not publish these data.

It is disappointing though. My amp will top out . Was hoping to avoid cutting wood in my apartment for the Ahuja OB I am trying out.

I think Manzanita kit (open baffle) is far more sensitive.

Checked it.

They are also in the range of 86 to 91 dB and recommend amp is 25W or more..mine is just 8W or max 10W with KT 88 valves . It is a single ended amp.

 

[grindstone]

Naveenbnc's thread below discusses your first question.

About the rest, it is difficult not knowing room size and expectations and preferences for loudness. 25W on-up would be "safe" for "most people in most rooms most of the time" etc. Using Sandeepsasi's math in his thread at the bottom of the page , I get 25W @ 2.5m...which is both funny and good. And yes, were I to recommend a min sensitivity for an 8W amp, I'd start at about 93dB (which would be the same kind of safe for my position), but I really don't know it would work for you w/o knowing how big your space is and how loud you listen and what you expect for dynamics. People really are different.

Monacor published 85 in the Katana instruction manual (and rated it 4 ohm). By itself, modeling the spx-31m OB from scratch using Monacor data in halfspace looks closer to 88+ over most of its passband and I'm not seeing less than 6.4 ohms impedance where it runs, either. The problem comes when you see that HF driver paralleled with a lower load--the two paralleled woofers so it's likely there are places where impedance is 3.something ohms and thus their 4 ohm rating. Okay, well, looking at the other drivers (spm-205/8), yeah 3.6 ohms around 260Hz maybe. All this without losses or a whole system w/ filters, BTW. To get closer, you have to get impedance and phase data for each driver and to add the filter and source and all that.

It could be better than the data suggests and might work if your needs and spaces are less-demanding. Alternatively, the factory driver data may be optimistic and my estimates are off. What it tells you is that you might want to use the 4 ohm tap on your output transformer (if avail) and a power supply that can deliver current to get the most out of your 8W amp into these lower loads if you choose to do it.

 

[drlowmu]

Unsolicited Suggestion :

With your interest in good audio, why don't you consider and concentrate on getting decent 101 dB Speakers. ??? Oh higher.

In my own view, this is on the best path to take in audio.

A 15 inch woofer, a two way.

Jeff

 

[Subbu68]

Unsolicited Suggestion :

With your interest in good audio, why don't you consider and concentrate on getting decent 101 dB Speakers. ??? Oh higher.

In my own view, this is on the best path to take in audio.

A 15 inch woofer, a two way.

Jeff

I already have a pair of Klipsch Heresy IIIs that are quite satisfying with TU-8200. That time I had eyed full rangers like Omega but had to look for something locally available.

But DIY fever has caught up again and ended up trying a Ahuja 12FRX a full ranger on a 2 X 3 layer packing boxes OB that is quite fascinating. But the prospects of getting a proper OB with wood is a bit iffy - wood work experience limited to school carpentry work and IKEA, living in an apartment so DIY waste is not so easy to manage and carpenters have been driven out of the city to an industrial area quite far away by the municipality. This kit from Monacor looked promising.

 

[Subbu68]

Naveenbnc's thread below discusses your first question.

About the rest, it is difficult not knowing room size and expectations and preferences for loudness. 25W on-up would be "safe" for "most people in most rooms most of the time" etc. Using Sandeepsasi's math in his thread at the bottom of the page , I get 25W @ 2.5m...which is both funny and good. And yes, were I to recommend a min sensitivity for an 8W amp, I'd start at about 93dB (which would be the same kind of safe for my position), but I really don't know it would work for you w/o knowing how big your space is and how loud you listen and what you expect for dynamics. People really are different.

Monacor published 85 in the Katana instruction manual (and rated it 4 ohm). By itself, modeling the spx-31m OB from scratch using Monacor data in halfspace looks closer to 88+ over most of its passband and I'm not seeing less than 6.4 ohms impedance where it runs, either. The problem comes when you see that HF driver paralleled with a lower load--the two paralleled woofers so it's likely there are places where impedance is 3.something ohms and thus their 4 ohm rating. Okay, well, looking at the other drivers (spm-205/8), yeah 3.6 ohms around 260Hz maybe. All this without losses or a whole system w/ filters, BTW. To get closer, you have to get impedance and phase data for each driver and to add the filter and source and all that.

It could be better than the data suggests and might work if your needs and spaces are less-demanding. Alternatively, the factory driver data may be optimistic and my estimates are off. What it tells you is that you might want to use the 4 ohm tap on your output transformer (if avail) and a power supply that can deliver current to get the most out of your 8W amp into these lower loads if you choose to do it.

View attachment 68643

I had tasted the limitation of the amp when I had my Jamo E855s with a sensitivity of around 86dB. Rather Klipsch Heresy showed what they could not do.

My current listening space is 10m x 4.5m, 3.2m high ceiling and speakers along the long wall. One third of the room to their right is the dining and prayer space opening to a kitchen through a counter and the foyer. It is a rented house. Even if I move room may not exceed this size.

My listening levels are not so loud - Indian classical, fusion and light music. Most of the listening is at night when wifey goes to bed.

The amp is a tube amp and has a 4 ohm tap but not quite sure now to beef up the power supply.

With Monacor I recon the amp may not drive it satisfactorily.

BTW could not see the threads you mentioned in your post. Would you mind pointing to them?

 

[drlowmu]

I already have a pair of Klipsch Heresy IIIs that are quite satisfying with TU-8200. That time I had eyed full rangers like Omega but had to look for something locally available.

But DIY fever has caught up again and ended up trying a Ahuja 12FRX a full ranger on a 2 X 3 layer packing boxes OB that is quite fascinating. But the prospects of getting a proper OB with wood is a bit iffy - wood work experience limited to school carpentry work and IKEA, living in an apartment so DIY waste is not so easy to manage and carpenters have been driven out of the city to an industrial area quite far away by the municipality. This kit from Monacor looked promising.

You need to improve the tube amp, to make the high efficiency speaker even more listenable. See my recent post on 12 resistors, critical to the TU-8200 's sonics, that will make a nice difference. Amps are the weakest link, not speakers, generally speaking, IME / IMHO.

Jeff

 

[grindstone]

BTW could not see the threads you mentioned in your post. Would you mind pointing to them?

Thank you for the additional information and apologies for omitting direct links.

Naveenbnc's thread
Sandeepsasi's thread

Sorry to ask so many questions, but don't want to mis-read. Is it one of these:

1) DIY-fever requires new standalone speaker to work on 8W and sound OB--everything else stays as-is.
2) OK with 12FRX on 8W but need domestically-approvable re-packaging hoping to adapt Katana frame
3) Both wrong want something else

Thanks.

 

[Subbu68]

1. Yes, want to build a speaker, an OB that works on the tube amp.
2. Not to adapt 12FRX to Katana frame. Was thinking of getting Katana kit when I saw it so as to avoid the wood cutting inside the apartment to make a baffle for 12FRX. No way to do the job outside the building as we are in the middle of the city. It's costing me nearly $850 to get a pair of Katana here. So if the amp does not drive it didn't want to risk the money. Yeah, it'll be an alibi to get a new amp,

 

[grindstone]

It's tough to suggest because everything sounds so expensive there. IMO, you just need more cone area (more drivers) for lower-freq support and the loudness contours and OB are working against you at late-night levels. Ideally, the "fix" is 2 15" coners--OB or slot-loaded or H-frame/U-frame/whatever. Bottom is LF-only. Sensitivity is usually "free" when you choose large. Domestically, you might want something else. Doing it w/o doing any construction leaves only kits and the only ones I know like that are the Linkwitz kits at Madisound and I don't even want to know what they'd cost to get there.

If it's me, I think the domestic-approval needs to drive size-acceptability. Picture something wrapped in a decor-complementary fabric with maybe a pre-finished cutting board on top. Then, absent pets/animals/stability issues, you can stay cardboard or use metal or whatever you can find in the city to get enough baffle and driver mounting structure that works. If you magnet-mount or do that Linkwitz leaf-spring type hanging, you could probably do something with threaded rod and posterboard. Modularity is good for that.
If you keep the low freq cross low enough, it wont destroy the coherence of the single-driver but will aid the "completeness" of the presentation on the 8W. Maybe something like mini-dsp is cheaper to get shipped there than crossover parts (?) Sounds like more amps wouldn't be an undue burden.

Maybe that's all too-much DIY and not "kit-enough"?

The thing with fullrangers is that, while beguiling, everybody (me included) wants "a little more fullrange" and there the paths diverge on how best to go. Almost everybody OB ends-up stacking drivers in normal course, too. It all just becomes a larger, more-involved, different thing. For that reason, maybe it's still worth taking a shot at the Katana kit if you listen at late-night-levels only in one end of the room. Everything else is either quite costly or requires construction so maybe it's the least-objectionable option provided you know not to expect it to fill such a large room at louder/daytime levels (?)