Not Very Interesting FRFR Story

[Chienmortbb]

I was going to put this on the other thread but it is now too long and unwieldy. The term FRFR means Full Range Flat Response (as a HiFi speaker should be for perfect reproduction of sound). However it seems to have been purloined to mean an active/powered cabinet with Full Range Flat Response. It is worth saying that it is possible to design a  FRFR cabinet that works with existing amplifiers . This was the design goal of the Basschat 1x12 and probably a number of commercial boutique cabinets.

Many bass amps do have a particular sound (often called voicing) but this is usually in the pre-amp section and that can often be bypassed by using the power amp in  or EFX return input on an SS head. So the FRFR system for you may already be close at hand but be aware that cabinets are also "voiced". It there is not tweeter or small driver in the cabinet, it will not be FRFR and many brands just chuck a nasty tweeter with no real crossover in a cab and hope it sounds good. So if you can only afford a Helix (other modelling units are avaialble) try you existing setup. it just may be what you need.

For me a nice head and cabinet just feels right although I would not be upset if offered an RCF, Yamaha or QSC active PA cab as my backline at some time.

 

[itu]

It is also good to understand that flat response and full range mean that the system is everything but efficient. Ordinary PA system has an efficiency that can reach 2 % while hifi systems can be as low as 0.01 %. This difference can be seen so that FRFR could be 200 times less efficient than an ordinary bass system. So you need LOTS of POWER to drive a FRFR, if it really has the features marketed. Two drivers do not automatically equal flat response, but maybe a slightly widened response.

Few simple equations:

Hifi system has 2 x 100 W / 8 ohm power output. Efficiency is 0.01 %. Maximum sound (not power!) output in watts is 2 x 0.01 W = 0.02 W.

Active bass speaker has 200 W / 8 ohm power output. Efficiency is 2 %. Maximum sound (not power!) output in watts is 4 W.

FRFR system with 4 W sound output with pretty good efficiency of 0.2 %. Needed amplifier: 2000 W / 8 ohm.

[Graham]

Hi-fi speakers however, are anything but flat - studio reference monitors should be - but a hi-fi speaker will have an inherent (often mid-scooped) sound

[Bridgehouse]

Just now, Graham said:

Hi-fi speakers however, are anything but flat - studio reference monitors should be - but a hi-fi speaker will have an inherent (often mid-scooped) sound

Absolutely - even some studio monitors seem a bit coloured to me. You have to pay a lot of cash to get true reference monitors - and actually home Hifi speakers in the lower price brackets are often the worst offenders for colouring sound!

[Chienmortbb]

I give up. High  Fidelity should mean that it faithfully reproduces the sound and I assumed that most good ones would be flat.

[BigRedX]

I think rather than flat you have to assume not deliberately coloured, which is what all bass and guitar amps and cabs are.

[Bridgehouse]

11 minutes ago, Chienmortbb said:

I give up. High  Fidelity should mean that it faithfully reproduces the sound and I assumed that most good ones would be flat.

I think nearly all reasonable studio monitors are flat - certainly mine are and they weren’t particularly expensive - but I’ve had a few home Hifi speakers which definitely weren’t flat - they were bass heavy and a bit mid scooped

[Bridgehouse]

I wonder if the term Hifi has been purloined to describe home stereo system speakers and that old “home Hifi” term whereas in fact it should be different - after all high fidelity should mean faithful reproduction of the original which it sometimes doesn’t!

[Phil Starr]

6 minutes ago, Chienmortbb said:

I give up. High  Fidelity should mean that it faithfully reproduces the sound and I assumed that most good ones would be flat.

Don't give up quite yet John. It's pretty obvious you want to discuss bass speakers not hi-fi (so called or not) Given that it is the speakers part of Bass Chat that doesn't seem too unreasonable

I think all you are saying is that the other very long FRFR thread is for those who are going down the route of using PA speakers and you want to share your experience of a passive FRFR cab designed for bass only and maybe started a debate with other people going down the same route.

I'll declare an interest in that I've seen your speaker being developed from my original single driver flat but not very extended frequency response design. 

I'd start off by asking how it has worked out, you started out pretty much just adding a simple horn and crossover but ended up with a really high quality horn and much more sophisticated crossover with a measured response which is as near as can be flat. How does it sound and does it achieve what you hoped? Will you be going back to a typical coloured bass cab any time soon?

[Bridgehouse]

^ I concur!

I really like the idea of a truly flat passive bass cab that can bring out the tonal flavour of an amp. 

My original thread was probably badly titled - but in the guitar/bass world frfr (rightly or wrongly) seems to be universally used to describe an active speaker that offers a full range and flat response for modelling amps. Having said that, the guitar works now has some impressive passive cabs that can be used with powered modelling amps. 

 

[Jack]

Given how unbelievably cheap PA power amps are these days (likely because of the aforementioned boom in the powered PA cabs market) I think a lot of us would be interested in a passive FRFR cab.

[Bridgehouse]

4 minutes ago, Jack said:

Given how unbelievably cheap PA power amps are these days (likely because of the aforementioned boom in the powered PA cabs market) I think a lot of us would be interested in a passive FRFR cab.

I bet a passive frfr cab with a built in 2/4u rack mount would be a killer as well... 

[stevie]

4 hours ago, itu said:

It is also good to understand that flat response and full range mean that the system is everything but efficient.

That is plain wrong. You can have certainly have flat response, full range and high efficiency.

[stevie]

3 hours ago, Graham said:

Hi-fi speakers however, are anything but flat - studio reference monitors should be - but a hi-fi speaker will have an inherent (often mid-scooped) sound

Most hi-fi speakers aim for a flat response, because research shows that this is what customers actually prefer. It is true that they don't always achieve it. The boom - tizz brigade that you describe is something else.

Edited November 6, 2018 by stevie

[jrixn1]

53 minutes ago, Bridgehouse said:

I bet a passive frfr cab with a built in 2/4u rack mount would be a killer as well... 

One thing you would lose is the DSP of an active speaker. My understanding is that it flattens the response and protects against over-excursion.
 

[Bridgehouse]

17 minutes ago, jrixn1 said:

One thing you would lose is the DSP of an active speaker. My understanding is that it flattens the response and protects against over-excursion.
 

Now if line 6 would do a powered helix in a 4u rack size....

[Phil Starr]

1 hour ago, jrixn1 said:

One thing you would lose is the DSP of an active speaker. My understanding is that it flattens the response and protects against over-excursion.
 

That's a good point, though it is interesting that all DSP actives don't sound the same. The other side of DSP is that there is usually a lot of other management going on. Active crossovers with bi amplified speakers are a real positive but you'll also be getting a fair amount of compression in many designs optimised to favour PA use rather than bass. My guess is that many of these things wouldn't be noticeable in a live band but I'd be interested in people's experiences. 

[itu]

2 hours ago, stevie said:

That is plain wrong. You can have certainly have flat response, full range and high efficiency.

Yes, I know, if I choose from those two. Could you please tell me, where can I find a system that has all three parameters and the price is reasonably flat, too?

For those interested, my stereo system has a pair of Gradient Helsinki 1.5. They should be reasonably flat, I think. Except the price. http://www.gradient.fi/en/

[Chienmortbb]

18 hours ago, jrixn1 said:

One thing you would lose is the DSP of an active speaker. My understanding is that it flattens the response and protects against over-excursion.
 

I only worry that DSP has too much influence over the signal. However ar Phil says, you would probably not notice it in a band situation.  As for the flatness, a passive crossover can be very flat but will not be as efficient as an active crossover whether analogue or digital (DSP). However with all the power we have on tap these days it is not really an issue IMHO.

[Jack]

23 hours ago, Bridgehouse said:

I bet a passive frfr cab with a built in 2/4u rack mount would be a killer as well... 

 

22 hours ago, jrixn1 said:

One thing you would lose is the DSP of an active speaker. My understanding is that it flattens the response and protects against over-excursion.
 

This is all true. I was going to suggest that lots of good PA amps have DSP built in, but now we're at the point where we have a self-powered relatively flat speaker system being DSP to be even flatter and we're back at standard FRFR cabs....

 

One of my favourite heads is the Peavey Tour, I like how it's a really clean pedal platform. I don't know how 'flat' it would actually be on a scope but it feels really clean and really neutral sounding. I often think about one of those mounted in an airhead as-flat-as-possible cabinet to make a really clean, full range combo.

Edited November 7, 2018 by Jack

[Chienmortbb]

Out of interest this is the the response of my BC1x12 MK2 as measured by Stevie. It does sound better than my HiFi speakers. The frequency response is the lower trace.