Bi-amping: HF amp selection / UMC200 output questions...

[nedseg]

Hi all, this is my first new post, and would REALLY appreciate suggestions/help.

I'm starting down the path of bi-amping my main speakers and have two items I don't know enough about yet.
Background:

- I'm using REW to try to capture decent 'before/after' measurements at each step along the way - partly because I can, and partly out of curiosity (ears will be final arbiters, regardless). (LOVE how nicely it works with the UMC200!)

- This is a UMC-200 7.1 ch system (ie, all UMC200 pre-outs in use, so can't use the bi-amp option), with an Emo 5ch amp for surrounds/center, Bryston 3B for the mains, and a Crown XLS driving a subwoofer.
- THIS project is only for addressing the Mains.

The PLAN is to passive bi-amp first (using existing LF and HF crossovers), then move up to a driverack venu360 for a fully active system (esp xover tuning).
(Speaker refurb is Part the First).

#1: Easy question first:
Can I just "Y" the UMC-200 main outputs to drive both HF & LF amps in parallel(until I get the dbx), or do I need more drive to do that (ie, buffer amp of some sort)?
(If NO, I'll just wait until I get the 360, but would like to assess improvements at each step along the way.)

#2: HF amp recommendations? This is the one I'd really appreciate feedback/suggestions on.

I'm using a Bryston 3B for full range currently, and will keep that for LF use.

At this point, the only HF amp candidates on my radar are a Bryston 2B LP (used), or Emo A150, mostly because both mfgrs have been great experiences, and I'm right on the tipping point of needing a half rack for amps anyway, and either would 'fit' nicely (yah, I know aesthetics are a silly way to chose, but I have to start somewhere).

The bryston is 1.4v input, the emo is not...other than that, so far a toss up, but I know there are other choices, too.

Budget for the HF amp is $500max, and both of these amps meet that criteria (so, no Macs).

I 'know' that tube amps are frequently recommended for horn systems HF, and am not totally opposed to that, but am NOT at ALL willing to go down the path of chasing 'better tubes' all over the planet - just want to plug it in and spend my efforts on tuning.
Also, I'm not all that sold on selecting an amp to 'sweeten' sound...and like the Bryston 3B sound just fine...and I expect to be able to tame any 'harshness' I might find? with the dbx and/or REW.

SO: Thoughts, Ideas, Opinions? All would be *greatly* appreciated.

PS. As much as I really really like the UMC200 for getting me 'where I am today', I also hope that Emotiva (emersa?) will offer up a new pre/pro with more network/usb DAC emphasis (I'm using an Oppo 103 currently for that, and can't really complain other than it's user interface is, uh, sparse), without room/EQ (won't need that), but most importantly great multi-channel decode, and very slimline (I buit a custom 'cabinet' that just fits the UMC-200 and Oppo 103:).
All my sources are digital now...and I have a vintage gear collection I can use for the little vinyl I have left.

Thanks all - I really enjoy following this forum!

[Gary Cook]

Of course you can Y output from the UMC-200, there is more than enough output and individual channel volume control. You just need to select amplifiers with matching gain for the bi amping. Keep in mind that you won't be able to individually tune the frequency responses so if the power amps have different sound signatures around the cross over points REW won't help you. In comparison, I wouldn't worry too much about wattage differences, in fact having less watts for the higher frequencies may be an advantage.

I didn't notice you mention what speakers you are using?

Personally, based on my experiences, I believe that bi amping (when there is a subwoofer in place) is a complete waste of time, money and effort. That the money is better spent elsewhere, but trying things is the fun part of our hobby (obsession).

Cheers
Gary

[405x5]

What he said......for sure.
Just reading your plan wore me out.

Bill

[nedseg]

Gary - Thanks, thats one item crossed off (I thought so, but wanted confirmation.)

The speakers are JBL L200/300s (ie, 200s w/added 077 supertweets and N8000 xovers).
Passive biamping would be stupid simple, as they already have separate LF and M/HF xovers.
(The sub is a JBL 4645C.)
I've had the speakers since new (1974), and had them modified to 'next to' L300 state by my JBL pro dealer a year later.
(I didn't include that info because I didn't want to sidetrack the main amp question, not to mention the hundreds of forum posts on the L200 topic elsewhere, which have led me to this approach - finally.)

I've spent my first years in retirement researching 'best practice' on upgrades for these, and have concluded that for Me, an active crossover is the best way to go, since it should allow me to upgrade/change LF/Mid drivers down the road, and requires mimimal changes to the cabinets, and can leave the old ones in place, either for passive or active bi-amping. And with the dbx, I get EQ, time alignment, and gobs of other features I've only scratched the surface of so far. (But no Alexa voice command - yet).

Plus, I have too many other demands on my time to chase what seem like endless tweeks to passive xovers, new or restored, and/or cabinet mods.
Granted, I may spend as much time fiddling with software on the dbx unit, but at least it won't require taking them out of service while doing so!
Oh, and the cost of the dbx unit is about the same as (probably less) than 'new' bass or mid drivers(actually different, since the originals seem to be fine, and I have a spare set if reconing is needed).

Finally, I'm generally happy with how they sound - after all my ears have been trained to them for 45 years! - but do think these relatively minor changes could improve them quite a bit - small changes via the UMC200 eq have already hinted at good outcomes, and that's mostly 'by ear'.
(I also finally have a listening space worthy of the 'best they can be'!)

And yes, I'm looking at amps in the 50w/ch class for the mid/high freq, ideally with level controls, as you point out.

If it weren't for this kind of unique circumstance, I'd agree with you on bi-amping as an end to itself.

Bill: -
NO kidding! Consider how exhausting it's been to get to this point for ME - just getting to decision points has been agnonizing.
Also, I'm retired from enterprise project management (and bench electronics tech/QC/tech mgt before that), so also a collision of occupational hazards, you might say.

OK. So: any other thoughts on small amps?

Thanks!

[leonski]

What is the crossover point?
What is the GAIN of the Bryston?

Before I suggested a 'small amp', I'd need to know the crossover intended. I know my Parasound A23, of wihch I have 2, have balanced and single ended ins as well as level controls. But is that the right amp?


Crossover point will generally determine the ratio of power above and below that point. The General Rule is that 350hz is considered the 50:50 point.
Gain is not QUITE as important, given modern active LL crossovers ability to gain match, but you want to be fairly close to begin with.

Will your proposed crossover solution provide gain tuning? Do you care about advanced functions like FIR filters, wihch have NO phase shift thru the passband? Or do you simply want to duplicate the
speaker level crossover, as an active solution?

for my 0.02$ I'd go with MiniDSP, not the DBX. But that's just me. You can even get an All Balanced In/Out version! or not.

The new 'Cubed' amp series from Bryston is so far beyond the B series as to render the early amps nearly obsolete. Again, depending on crossover frequency, a pair of the 2.5 series would kill. The JBL stuff is pretty high sensitivity as they stand. you don't need HUGE amounts of power, and I'm unfamiliar with the power handling capacity (real) of the L200/300 series. My last hands-on with JBL was a pair of the 4311 studio monitors and a very Excellent copy speaker made here in SoCal by a boutique company called RSL. (Rogers Sound Labs) which was highly regarded and still used by a few die-hards.

[nedseg]

Hi & thanks!
The LX16 crosses the LE15Bs over at 1200hz, so the new amp would handle above that (for the passive bi-amp, step 1).
(The N8000 crosses over from the LE85 to the 077 at 8000hz.)
Not sure what gain you're asking for on the Bryston?
The 3BNRB has no level controls, which is why I want to have gain controls on the new MF/HF amp.

BTW, one question I have you might also be able to answer is whether, when using the existing crossovers (ie, removing the connection between the two and connecting instead directly to two amps) I'd need to add protection caps for the MF/HF - I'm assuming this would be covered by the caps in the N8000 circuit?
Both the 3BNRB and the (possible) 2B LP do not have soft start (a mark against it)...which hasn't been a problem with the 3B as I just leave it powered up all the time.

Another point I've wondered about is whether the existing xovers will function properly for bi-amping without the designed loads on them.
For example, doesn't (say) the LX16's freq response depend in part on the (originally designed) LE85 load? (In my case N8000 + LE85+077 load.)

If so, then I might just skip the passive bi-amp step (which I'm doing mostly to spread the costs out over time a bit) and just go directly to active....would just have to wait longer to implement it, effectively.

FWIW, just saw this old thread here about the Bryston 2B LP I've been considering...not directly relevant, but interesting.
emotivalounge.proboards.com/thread/26307

For the active step (2), I want to experiment with different xover points for the LE15 (and/or others I might try in there, such as a 2235).
And, yes, gain control could/would presumably be done in the active xover if/when I get to that stage.
I'm also interested in phase control FIR filters in the proposed active device, as well as other features (but am still reading up on those).

I have not ruled out the miniDSP, certainly would save a few bucks.
But, if I'm reading things right, the dbx360 would get me one more xover channel, which I thought might be possible to use to fine tune the subwoofer xover (below the LE15s) as well...a 'freebie', if so.

The Bryston 3BNRB seems to be a good match to the L200/077s, power/handling wise - I've never come even close to clipping it, and don't like earsplitting sound levels anyway.
My first few REW measurements suggest that all the drivers are working in good condition, but will do more tests.

I'd LOVE to have newer Brystons, but they are waay beyond my budget, which, for the new MF/HF amp is around $500...so looking (mostly) at used...but am sure open to suggestions.

Thanks so much for your comments/suggestions!

[leonski]

First, I'll admit to not being real familiar with the DBx and Beheringer and other crossovers.
A buddy of mine uses a Marchand for which you buy modules of the desired characteristics.

The MiniDSP, OTOH, can be had as a Balanced I/O or single ended or BOTH in from 2 to 10 inputs.

Check out my 'Idea Noodle' thread which has a block diagram of an amp designed for active biamp.
It has a MiniDSP and a pair of the nCore 400 amps as well as power supplies.

Just my opinion, but I'd START with such a noodle for you. Figure out what you want and than start
a block diagram.

For the Cost-No-Object school? PASS makes a crossover which is amazingly flexible and clean.

www.stereotimes.com/amp021513.shtml

Passive and speaker level crossovers are at least partly based on the load. I currently do a passive biamp system
using the speakers crossover. But the gains are minimal, and nothing like the potential bennies of going active.

Gain is important for your needs. Amps have gain. If you have 2 amps for a biamp system and amp#1 is 26db gain and the other is 29db gain? That's potentially
a problem. If you look into the schematics of your current speakers crossover, you may see some resistors. They can be used to 'pad' down a more sensitive (NOT efficient)
driver to match the rest of the system. My RSL copies of JBL 4311s had level controls as did the 4311s.

[nedseg]

Thanks, more really good stuff!

Yup, I get that gains have to 'match' their loads...is why I slightly prefer one with level controls..so I can match the big one easily (for the passive step, at least.)
I have read your noodle thread...great stuff, and did get me looking into the Hypex amps...still on my radar.

THe marchand is out of my range, as is the Pass (even the DYIs), and since I kind of feel 'time's winged chariot', not quite as eager to get into DIY, or design/build stuff myself (and have other non-audio DIY stuff already lined up on the bench) as I used to be...and, yah, kind of eager to Get To Done(ish) quickly...patience is Soo Hard.
The dbx360 has more I/O (3 in, 6 out) than the minidsp, and is still reasonably affordable, but haven't ruled either out yet...lots more reading to do on both...whether I can make use of that 3rd "in" will be one of the deciding factors.

Ooog, thanks! I *totally* forgot that both those xovers have pads/switches on them...too deep in the weeds, I guess, and tend to keep schemas in my head, which is becoming more and more 'faulty' every year Kool.

You sure win the prize for helpfulness!! So much thanks!

[leonski]

I forgot ONE major thing:

sound.whsites.net/bi-amp.htm

Read this and than go on to part II. Very easy understand and written for comprehension.

I think that's it for me!

[nedseg]

Thanks again - I've read that, but a while ago, a refresh sure wouldn't hurt.
You've been very helpful.
I'll report back as I progress & procure!
(Still looking for a nice little amp & still considering the old Bryston 2B LP

[nedseg]

Just a quick update on my amp search & upgrade results.

First, many thanks to those who helped out, esp Leonski, who got me thinking a bit more 'critically'!

I ended up taking a chance on a low cost, used Crown DC75A (~40wpc) on CL locally, and Got Lucky - turns out it's a near perfect match for the (super efficient) JBLs...and, boy is that thing well built (2001 vintage, US made) - very neat little amp.

Disconnecting the Low and Mid/High crossovers from each other did change their response curves slightly (measured with REW), and made for minor differences in sound, but not a WoW! by itself...pretty much as predicted.

The real magic came in applying the REW suggested PEQs on the UMC-200 - especially as compared to the prior EMO-Q settings.
I just continue to be impressed with that little pre/pro - I sure get a lot of bang for the buck out of it!

Anyway, the sonic differences (and REW measurements) before and after are startling; tighter bass, clearer highs (etc etc...) - just better balanced all around.

I found it entertaining to do a bunch of 'random/blind' (hah hah) comparisons between FLAC and MP3/320 CD rips of mine (as well as some purchased ones)...and could easily ID the lossless ones immediately, every time.
Prior to these changes I'd get it right about 50% of the time.
And, some recordings that I'd considered problematic before now sounded 'normal' (eg, flutes, and some guitar music).
THe sound is now much closer to live concerts I've attended recently (mostly 'acoustic' trios, like Loreena McKennitt).

Next up: active crossover - but am so happy with this as is, I may put that off a while.

Thanks again!