BillFitzmaurice.info

Hi all,

I am working on my first build of two TLAH Pros and 1 THTLP (RSS390HF-4 15" driver - plan to make it about 36" wide).

I have been reading through the forum trying to understand voltage and amp selection but I have a few questions I haven't been able to answer. I apologize if this is covered somewhere I missed. I am new to this so will try to break down what I understand so far.

1. The RSS390HF-4 says it has a power handling of 500W at 4ohms. This means in theory they can handle up to sqrt(500x4) = 44v. But in the plans, Bill mentions that amping with anything over 200w is superfluous due to the efficiency of the horn design, so does that mean I should limit to sqrt(200x4) = 28v?

2. I assume that 200W recommendation includes any amp headroom? So I would be looking for an amp that can provide 200w per channel?

3. I am in Spain so have been considering the thomann amps, so for example https://www.thomann.de/gb/the_tamp_ta450_endstufe.htm. I will only have 1 sub so would just be running one channel off this amp unless it is better to consider a 4 channel amp and run all speakers off it, but in my mind this would make limiting, processing and crossover harder as well as matching amps to speakers. Two amps better than one then? Does that amp look ok or should I be considering something else?

4. Also in the THTLP plans, Bill discusses wiring for dual coil drivers but I can't find a reference to this in the RSS390HF-4 so as far as I can tell this is a single coil driver and so I will, in fact, be working with 4ohms. If I am not correct about that then I would be working with 8 ohms and that would, of course, affect amp requirements and these calculations.

5. For the TLAH PRO I am thrown by how to calculate limiting voltage due to there being multiple drivers in series/parallel configuration. The Eminence Alpha 8a is rated at 125W and will be wired according to the plans at 4 ohms. So max voltage for 1 driver is sqrt(125x4) = 22V. But since there are 8 drivers, does this affect this calculation or is 22V the max voltage for the cabinet for limiting purposes? Sorry if this is somehow a stupid question.

Once I am sure on these numbers I can better select amps. This is the first time I am doing this so any wisdom about what to look for in an amp is much appreciated. I also have some questions about crossovers and processing (minidsp ddrc24 vs dbx driverack PA2) but I will post those in the relevant forum section as a separate thread.

Thanks for your help!
Jeremy

As with all of our tops there's no limit mentioned for the TLAH Pro because you'll hear it distorting long before damage is possible. As for the THTLP no limiting is mentioned because it's a home theater sub, and home theaters don't have limiters. If this is a pro-sound application the THTLP is the wrong sub. If it's a home theater the TLAH Pro is probably the wrong top.

Hi Bill,

Thanks very much for the reply. So this is for a mixed-use residential installation. We watch movies in this room but also have parties and DJ (classic house music mostly with vocals, etc.). We also plan to potentially broadcast some internet video/radio dj sessions from this room at some point, but mostly just for listening to, dancing to, and enjoying music and watching movies. The room is much longer than it is wide (about 27.9' x 12.75') with the projector setup to display centered on the long wall with the highest ceiling. There is a sloped ceiling (sloping the short way across the room) with the highest point being about 9' and the lowest 7.67'. The room shape made me choose the TLAH PRO as they will be positioned in the two corners (facing inwards 45 degrees) on the wall with the screen and the wide-dispersion pattern seemed best to cover the whole room reasonably well. I also don't have a lot of depth to work with for speakers so the low profile of the TLAH is ideal for me as most other boxes won't fit.

Just out of curiosity why is the THTLP not recommended for a pro sound/music program? Is the response two slow for transients or music-range frequencies, or am I misunderstanding and it is just that the additional low-frequency response is not necessary for that use?

The goal with the installation is to get a more or less even coverage across the room with the center of the room being the focal point, as well as good sound quality at low to moderate volumes. I am looking more for full-spectrum sound reproduction and don't plan on trying (too hard) to shake the house down, although I am sure that is possible with these designs.

I have already purchased all the drivers and had them shipped over to me in Spain from parts express, customs duties paid, etc. so hopefully I can make this installation work somehow with these drivers. Would building the THTLP less wide than 36" improve things at all?

Thanks again!
Jeremy

jhayward30 wrote: Just out of curiosity why is the THTLP not recommended for a pro sound/music program?

It uses boundary loading and cabin gain for both sensitivity and low frequency extension. You get both in a home sized room. You can't count on getting either in a club, so the pro-sound subs are designed accordingly.

Okay thanks! So hopefully then in my case it should do ok as I will be able to put it in a corner and the room is not too large.

So for the TLAH PRO would a 450w per channel amp be reasonable taking into account a little headroom? If so I will plan on one of those and a 200w for the sub.

Jeremy

jhayward30 wrote: So for the TLAH PRO would a 450w per channel amp be reasonable taking into account a little headroom?

Considering the size of the room I'd say you'd have about 350w of headroom. I run my standard TLAH as loud as I could possibly want in my living room with an 80w/ch receiver, and the Pro has considerably higher sensitivity.

Yikes.. way off Okay, that makes it simple then. Thanks again for all your help!

Jeremy