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BassManGraham

Best Power Amp for TECH 21 Sansamp RBI preamp?

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Have had a much under-used Sansamp RBI preamp kept rack-mounted as stand-by for gigs for a while.
Not really been used as my bass heads have had decent preamp and tone shaping capabilities and good DI outs, which didn't need any enhancement. Didn't see the point of running a preamp into another preamp?
I am now thinking of getting a class D power amp to give the RBI preamp the use it deserves.
Any players use these preamps with power amps?
Looking for around 350- 500W into 8ohms and 500-900 into 4 ohms respectively.
Welcome comments:

Edited by BassManGraham

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Depends on budget but this may suit; http://www.bassgear.co.uk/product/demeter-minnie-800d-power-amplifier/

A lot of people on here rave about their retro-looking pre+power amp & I believe this is just the power section from there.

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Guest bassman7755

Well given you already need a rack for the RBI I'd look at some lightweight rack PA power amp, something like this http://www.gear4music.com/PA-DJ-and-Lighting/Crown-XLS1000-DriveCore-Class-D-Power-Amp/QB8?origin=product-ads&campaign=PLA+Shop+-+GENERIC&adgroup=GENERIC&medium=vertical_search&network=google&merchant_id=1279443&product_id=34100d1&product_country=GB&product_partition_id=127285164799&gclid=CKH46PL5hckCFY9uGwodkoAJ-A

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[quote name='Lw.' timestamp='1447156941' post='2905300']
Depends on budget but this may suit; [url="http://www.bassgear.co.uk/product/demeter-minnie-800d-power-amplifier/"]http://www.bassgear....ower-amplifier/[/url]

A lot of people on here rave about their retro-looking pre+power amp & I believe this is just the power section from there.
[/quote] Thanks, not seen these before, but bit on the pricey side and Ideally looking for a 1U or 2 U rack mount unit.

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[quote name='bassman7755' timestamp='1447162045' post='2905372']
Well given you already need a rack for the RBI I'd look at some lightweight rack PA power amp, something like this [url="http://www.gear4music.com/PA-DJ-and-Lighting/Crown-XLS1000-DriveCore-Class-D-Power-Amp/QB8?origin=product-ads&campaign=PLA+Shop+-+GENERIC&adgroup=GENERIC&medium=vertical_search&network=google&merchant_id=1279443&product_id=34100d1&product_country=GB&product_partition_id=127285164799&gclid=CKH46PL5hckCFY9uGwodkoAJ-A"]http://www.gear4musi...CFY9uGwodkoAJ-A[/url]
[/quote] Thanks. yes this is more within my budget. I will also consider the Crown XLS1500 which is a very good price on Thomann at the moment.

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[quote name='BassManGraham' timestamp='1447187164' post='2905699']
I will also consider the Crown XLS1500 which is a very good price on Thomann at the moment.
[/quote]

That was my rig for a while...



Looked quite cool but, if I'm honest, the RBI wasn't such a great match with the XLS1500 as it didn't seem to put out a strong enough signal to really drive the power amp. It was alright, but nowhere near as loud as the XLS is actually capable of when used for PA and driven by a decent mixer.

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[quote name='Ed_S' timestamp='1447198217' post='2905803']
That was my rig for a while...



Looked quite cool but, if I'm honest, the RBI wasn't such a great match with the XLS1500 as it didn't seem to put out a strong enough signal to really drive the power amp. It was alright, but nowhere near as loud as the XLS is actually capable of when used for PA and driven by a decent mixer.
[/quote] Hi Ed, many thanks for the really useful feedback, seems I will have to think again!!

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[quote name='BassManGraham' timestamp='1447204309' post='2905841']
Hi Ed, many thanks for the really useful feedback, seems I will have to think again!!
[/quote]

Crown's new Drivecore 2 series should solve this - switchable input sensitivity 1.4V/0.775V

http://www.crownaudio.com/en-US/products/xls-1502

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[quote name='dincz' timestamp='1447220527' post='2905859']
Crown's new Drivecore 2 series should solve this - switchable input sensitivity 1.4V/0.775V

http://www.crownaudio.com/en-US/products/xls-1502
[/quote]

Nice.. and the right colour this time, too! Aside from the input sensitivity the old ones were/are great and, although I didn't rate the RBI/XLS combination, I still have two 1500s in a 4U rack for occasional PA duties. Might have to see about getting a v2 to try with bass preamps :-)

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[quote name='dincz' timestamp='1447220527' post='2905859']
Crown's new Drivecore 2 series should solve this - switchable input sensitivity 1.4V/0.775V

[url="http://www.crownaudio.com/en-US/products/xls-1502"]http://www.crownaudi...oducts/xls-1502[/url]
[/quote] Now that looks more like it Dincz, thanks for bring it to my attention. The switchable input sensitivity is a great idea, I'll remember this one! Might try and acquire one always useful for PA/monitor duties!

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[quote name='Ed_S' timestamp='1447225421' post='2905865']
Nice.. and the right colour this time, too! Aside from the input sensitivity the old ones were/are great and, although I didn't rate the RBI/XLS combination, I still have two 1500s in a 4U rack for occasional PA duties. Might have to see about getting a v2 to try with bass preamps :-)
[/quote]
Hi Ed, Other than the RBIs lack of signal to drive the Crown XLS1500 was the sound quality OK?. Were you using the Crown XLS in Bridged or stereo mode? Would a active bass make a difference? I am thinking about the Crown XLS 1002 produces 1100W in to 4 ohms bridged which seems more than ample if the new higher sensitivity input allows the RBI to drive the power amp. Appreciate your feedback. Cheers

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[quote name='BassManGraham' timestamp='1447260474' post='2906233']
Hi Ed, Other than the RBIs lack of signal to drive the Crown XLS1500 was the sound quality OK?. Were you using the Crown XLS in Bridged or stereo mode? Would a active bass make a difference? I am thinking about the Crown XLS 1002 produces 1100W in to 4 ohms bridged which seems more than ample if the new higher sensitivity input allows the RBI to drive the power amp. Appreciate your feedback. Cheers
[/quote]

Hi Graham,

Other than the mismatch between the RBI and XLS, the power amp is great - so good that I bought another and shipped out my old Yamaha P3500S which I never thought I'd get rid of... but (quite unscientifically) the rack case with both XLS1500s in it is probably lighter than the Yamaha on its own.

When I was using the XLS for bass, I was using it bridged into a Barefaced Super 12 (sensitive 4ohm 2x12 in the unlikely event that you haven't come across one on your travels) and whilst it was loud enough, the XLS was on full and the settings that I had to use on the RBI were such that an excessive amount of hum / mains noise / RFI etc. was coming through. In the end, I just dropped the Crown out of the rack and put my Markbass LM2 in, which eventually resulted in me just using the LM2 without the rest of the rack.

Hindsight being the wonderful thing that it is, I wish I'd tried putting my MXR micro-amp between the pre and power to just give the signal a push going into the amp, but I didn't think of it at the time, and I've since traded the RBI as it wasn't getting used, so I can't give it a go. I don't think an active bass would make much difference; the signal needs to be hotter leaving the preamp, not going into it.

I think the new XLS1002 would be fine bridged into a 4ohm cab, though I might be tempted to go for the 1502 myself as it would have a bit more poke per-side for conventional PA / monitor use, so might be more handy from a double-duty perspective for the same size and weight. That, and hey, you can always turn down if you've got too much power but turning up past full can be tricky.

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[quote name='Ed_S' timestamp='1447198217' post='2905803']
That was my rig for a while...



Looked quite cool but, if I'm honest, the RBI wasn't such a great match with the XLS1500 as it didn't seem to put out a strong enough signal to really drive the power amp. It was alright, but nowhere near as loud as the XLS is actually capable of when used for PA and driven by a decent mixer.
[/quote]

Sorry but this is not correct. We have been through this numerous times on the Talk Bass forum years back. We even measured our RBI's output to duplicate Crown's test specs. These are the results:

[quote][color=#141414][font=verdana, geneva, lucida,]With a -10dB 1kz sine wave (which is what Crown uses for the specs) (.3V rms which is an instrument level signal) and all the EQ controls on the RBI set flat, output level at 3 o'clock and the blend off, the output voltage of the RBI is 3.6 V rms. [/font][/color][/quote]

:Part of the problem is that Crown makes power amps for sound reinforcement applications not musical instrument use. While a pro multi channel mixer with all its channels being driven to the max can put out a significant signal level and exceed the input level requirements of the Crown there is no extra output to be had. You would simply have to turn down the gains on the Crown to prevent the mixer from overloading the input of the power amp. You would have to do the same with the RBI.

The wattage rating of the power amp and your speaker system are only part of the equation. Typically many bass cabs that handle higher wattage ratings are also lower efficiency. You have to look at the SPL the cab is capable of reproducing and most bass cabs will not compete with high quality sound reinforcement speaker systems. With an amp like the Crown if you're looking for 1000 watts RMS, Crown will recommend a 2000 watt power amp. This is because music is not a steady sine wave. If you don't have the added headroom the power amp will clip at any sustained sounds that go beyond the RMS limit. They can handle small peaks but not continuous peaks.

I would recommend to the OP to try using the RBI into his amps EFX loop return (if provided) to bypass the preamp section of the amp. This will give you a good idea of the sound of the RBI on its own. There is also a way to use the RBI independently from your amp's preamp with certain models of amps.

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[quote name='Tech21NYC' timestamp='1447690832' post='2909524']
Sorry but this is not correct. We have been through this numerous times on the Talk Bass forum years back. We even measured our RBI's output to duplicate Crown's test specs. These are the results:



:Part of the problem is that Crown makes power amps for sound reinforcement applications not musical instrument use. While a pro multi channel mixer with all its channels being driven to the max can put out a significant signal level and exceed the input level requirements of the Crown there is no extra output to be had. You would simply have to turn down the gains on the Crown to prevent the mixer from overloading the input of the power amp. You would have to do the same with the RBI.

The wattage rating of the power amp and your speaker system are only part of the equation. Typically many bass cabs that handle higher wattage ratings are also lower efficiency. You have to look at the SPL the cab is capable of reproducing and most bass cabs will not compete with high quality sound reinforcement speaker systems. With an amp like the Crown if you're looking for 1000 watts RMS, Crown will recommend a 2000 watt power amp. This is because music is not a steady sine wave. If you don't have the added headroom the power amp will clip at any sustained sounds that go beyond the RMS limit. They can handle small peaks but not continuous peaks.

I would recommend to the OP to try using the RBI into his amps EFX loop return (if provided) to bypass the preamp section of the amp. This will give you a good idea of the sound of the RBI on its own. There is also a way to use the RBI independently from your amp's preamp with certain models of amps.
[/quote] Many thanks for this. I will try my RBI into my Genz Benz Shuttle Max 9.2 & Streamer 9 FX loop returns. Ideally I want to take bass head out of rack and just use a power amp. Are there any power amps TECH 21 would recommend or endorse?

Edited by BassManGraham

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[quote name='Tech21NYC' timestamp='1447690832' post='2909524']
Sorry but this is not correct. We have been through this numerous times on the Talk Bass forum years back. We even measured our RBI's output to duplicate Crown's test specs. These are the results:

:Part of the problem is that Crown makes power amps for sound reinforcement applications not musical instrument use. While a pro multi channel mixer with all its channels being driven to the max can put out a significant signal level and exceed the input level requirements of the Crown there is no extra output to be had. You would simply have to turn down the gains on the Crown to prevent the mixer from overloading the input of the power amp. You would have to do the same with the RBI.

The wattage rating of the power amp and your speaker system are only part of the equation. Typically many bass cabs that handle higher wattage ratings are also lower efficiency. You have to look at the SPL the cab is capable of reproducing and most bass cabs will not compete with high quality sound reinforcement speaker systems. With an amp like the Crown if you're looking for 1000 watts RMS, Crown will recommend a 2000 watt power amp. This is because music is not a steady sine wave. If you don't have the added headroom the power amp will clip at any sustained sounds that go beyond the RMS limit. They can handle small peaks but not continuous peaks.

I would recommend to the OP to try using the RBI into his amps EFX loop return (if provided) to bypass the preamp section of the amp. This will give you a good idea of the sound of the RBI on its own. There is also a way to use the RBI independently from your amp's preamp with certain models of amps.
[/quote]

Sorry if you feel that I've spoken out of turn. All I can say is that my cabs at the time were a Barefaced Super 12 and a Markbass STD104HR (both 4ohm and neither considered to lack sensitivity) and the most I was wanting to get out of the rig was the equivalent volume of my 500W Markbass head, so the bridged 1500W XLS was more than the 'recommended' 2x over-spec. The RBI didn't work well for me, but my old Peavey TB-Raxx preamp worked fine in its place - I just didn't want to use the Peavey in my gigging rack and risk damaging it. I swapped the XLS out and the RBI then worked fine into my Markbass head (just as you yourself suggest) and the XLS proved its worth as a PA amp. Given that I'd proven all the bits were fine on their own and with other combinations of gear, the sensible conclusion seemed to be that the RBI and XLS just didn't work well together for some reason. One not having the requisite poke to drive the other was what I came up with, but I admit it was just a guess and I'm happy to stand corrected.

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[quote name='BassManGraham' timestamp='1447698184' post='2909615']
Many thanks for this. I will try my RBI into my Genz Benz Shuttle Max 9.2 & Streamer 9 FX loop returns. Ideally I want to take bass head out of rack and just use a power amp. Are there any power amps TECH 21 would recommend or endorse?
[/quote]

We don't have any specific power amp to recommend. I was mainly responding to the compatibility aspect of the thread. Any power amp should work. It depends on how much continuous power you require. With our amps that use a digital power amp we are able to optimize the system so the preamp section doesn't overload the input to the power section. I've used Crown power amps, Carvin and various other amps over the years. Our band does a lot of large shows and though most gear we use are powered speakers I still see Crown, Crest and QSC power amps from time to time. It really comes down to how much you want to spend and carry. No matter how much power you have you will get to a point of diminishing returns if you don't bring enough speakers.


[quote name='Ed_S' timestamp='1447753992' post='2909954']
Sorry if you feel that I've spoken out of turn. All I can say is that my cabs at the time were a Barefaced Super 12 and a Markbass STD104HR (both 4ohm and neither considered to lack sensitivity) and the most I was wanting to get out of the rig was the equivalent volume of my 500W Markbass head, so the bridged 1500W XLS was more than the 'recommended' 2x over-spec. The RBI didn't work well for me, but my old Peavey TB-Raxx preamp worked fine in its place - I just didn't want to use the Peavey in my gigging rack and risk damaging it. I swapped the XLS out and the RBI then worked fine into my Markbass head (just as you yourself suggest) and the XLS proved its worth as a PA amp. Given that I'd proven all the bits were fine on their own and with other combinations of gear, the sensible conclusion seemed to be that the RBI and XLS just didn't work well together for some reason. One not having the requisite poke to drive the other was what I came up with, but I admit it was just a guess and I'm happy to stand corrected.
[/quote]

How were you using the RBI into the Crown? What were the specific settings on both the RBI and power amp? What type of bass, passive or active? Any other effects in line before the RBI and in the loop or placed between the RBI and power amp. The thing to remember is that those specs are usually based on a 1kHz sine wave, we typically use a 500 Hertz sine wave.

You mentioned the amp worked fine for the PA. What speakers and system? Bass is the hardest thing to amplify. You need more power for the low end. Were you running the bass through the PA system? I'm not trying to give you a hard time but playing one instrument through a bass cab situated on the floor is not the same as a PA system with speakers that are pole mounted or suspended in the air with sub woofers etc.

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[quote name='Tech21NYC' timestamp='1447774697' post='2910236']
We don't have any specific power amp to recommend. I was mainly responding to the compatibility aspect of the thread. Any power amp should work. It depends on how much continuous power you require. With our amps that use a digital power amp we are able to optimize the system so the preamp section doesn't overload the input to the power section. I've used Crown power amps, Carvin and various other amps over the years. Our band does a lot of large shows and though most gear we use are powered speakers I still see Crown, Crest and QSC power amps from time to time. It really comes down to how much you want to spend and carry. No matter how much power you have you will get to a point of diminishing returns if you don't bring enough speakers.

I have just tried my RBI through the FX return of my GenzBenz Shuttle Max 9.2 as suggested. Sounded great & plenty volume (using a pair of Vanderkley 600w MNT112 Bass cabs).

I have also just tried the RBI through a friends T-Amp E800 (a budget power amp, with input sensitivity options). I tried in stereo mode using two outputs from RBI and Bridged
mode, both gave plenty volume & power for my needs.

Appreciate your feedback guys.



How were you using the RBI into the Crown? What were the specific settings on both the RBI and power amp? What type of bass, passive or active? Any other effects in line before the RBI and in the loop or placed between the RBI and power amp. The thing to remember is that those specs are usually based on a 1kHz sine wave, we typically use a 500 Hertz sine wave.

You mentioned the amp worked fine for the PA. What speakers and system? Bass is the hardest thing to amplify. You need more power for the low end. Were you running the bass through the PA system? I'm not trying to give you a hard time but playing one instrument through a bass cab situated on the floor is not the same as a PA system with speakers that are pole mounted or suspended in the air with sub woofers etc.
[/quote]

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I almost got one of these a few weks ago. It was going to replace my Markbass F1 and to be used with my VTBass Di. only reason i didnt was that i relasied i had enough power already.

http://www.amazon.co.uk/Behringer-NU1000-Inuke-1000W-Amplifier/dp/B005EHIN12

The brand does not put me off at all ;-)

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[quote name='Tech21NYC' timestamp='1447774697' post='2910236']
How were you using the RBI into the Crown? What were the specific settings on both the RBI and power amp? What type of bass, passive or active? Any other effects in line before the RBI and in the loop or placed between the RBI and power amp. The thing to remember is that those specs are usually based on a 1kHz sine wave, we typically use a 500 Hertz sine wave.

You mentioned the amp worked fine for the PA. What speakers and system? Bass is the hardest thing to amplify. You need more power for the low end. Were you running the bass through the PA system? I'm not trying to give you a hard time but playing one instrument through a bass cab situated on the floor is not the same as a PA system with speakers that are pole mounted or suspended in the air with sub woofers etc.
[/quote]

Yeah, I get what you're saying - there are a lot of possible variables on both sides and I honestly have no idea at this point what the settings on either piece of equipment were when I was experimenting with the RBI/XLS rack. I'm not the least technically minded person out there and I did experiment quite thoroughly with settings, patching and instruments, but it's feasible that I missed something. It's interesting to reflect that my backup rig in the event of a complete failure is a choice of BDDI or VTDI into a Bose A1 PackLite power amp, and that works brilliantly and is every bit as loud and clear as you'd expect... maybe even louder!

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[quote name='Tech21NYC' timestamp='1447690832' post='2909524']
Sorry but this is not correct. We have been through this numerous times on the Talk Bass forum years back. We even measured our RBI's output to duplicate Crown's test specs.[/quote]

A little bugbear of mine - Sansamp specs quote levels in dB and it's not clear if that means dBm, dBV, dBu.

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[quote name='dincz' timestamp='1447844579' post='2910832']
A little bugbear of mine - Sansamp specs quote levels in dB and it's not clear if that means dBm, dBV, dBu.
[/quote]

Specifications for something like our SansAmp products don't really translate into the sound reinforcement world. Even the specs that manufacturers of power amps like Crown and QSC give are only for comparative purposes. The main difference is that those type of products are designed for sound "reproduction" vs products like ours that are for sound "production." Power amps like Crown or mixers like Mackie aren't designed to create "intentional" distortion like our SansAmps. Did you ever try to look up the specs for a Big Muff. When we did the measurements I mentioned previously for the RBI we used the same type of test that power amp manufacturers use but used a more "instrument relevant" frequency of 500Hz vs 1kHz but even that is not all that helpful in a real world application. We set the unit totally clean as you can't really do reliable measurements when you start "intentionally" distorting the preamp.

People that use power amp's for sound reinforcement don't get bogged down by these specifications like the people I encounter on bass forums. They understand that if you are trying to power a speaker system that has a rating of 1000 watts the general rule of thumb is to use a power amp rated at 2000 watts, The sound company my band uses will triple the power when using newer digital power amps as he feels they don't translate the low end as well as the old lead sled power amps do.

If you look at those big powerful 300-400 watt tube amps that Mesa and Rivera designed for bass and guitar applications those power amps can be driven to full output with a passive bass guitar whereas most sound reinforcement amps will require a preamp to boost the signal. The difference is that one product was designed for guitar & bass and the others are designed to work with mixers.

If you'd like to give me the specific output of "your" bass perhaps I can give you the information you require. I doubt you can arrive at such a figure. I'm not trying to be snarky here but what I think is behind much of this "preamp driving the power amp driving the speakers" debates is that many players are kidding themselves about the reality of live sound. They want to walk in with their 4lb bass amp and a neo 210 cab and have 3000 watts of power. There is no substitute for more speakers pushing air. I've yet to hear anyone play an old school Ampeg SVT driving 810's that wasn't loud enough.

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Thanks for your reply. I appreciate the difficulties but my main point was that "dB" is not a level unit but a relative unit. -10dB relative to what? If using the absolute values dBm, dBu, dBV might be confusing - and I agree that it might be - then why not simply specify levels in volts? Power amp manufacturers often use this convention to specify input sensitivity anyway, and it makes level compatibility visible at a glance.

As regards pedals like the Big Muff, it's usually safe to assume that they're designed to connect to an instrument level input so there's less guesswork involved.

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Whatever the numbers, my own personal experiences with an RBI or RPM or both driving an original XLS1500 were that they had no issues fully driving the amp without maxing the volumes of the preamps. They also happened to sound rather epic especially when the two pre's were linked together and dumped into an 8x10 ;-)

I still have both preamps and the amp but prefer my Kemper with various profiles of that setup nowadays.

Edited by intime-nick

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Just to conclude this thread I eventually bought a Crown Drive Core XLS 1002 which gives me 1100W bridged into 4 Ohm.

Early days but I am very impressed with this great value and nice quality power amp which works really well with My Sansamp RBI. I am using it into a pair of Vanderkleys.

The Crown amp is very easy to program (even by a techno phobe like me) low pass, high pass or a selected bandwidth to cut too much low end rumble. The switchable input sensitivity is brilliant.

Many thanks for all the your comments and suggestions.

I will post a pic soon too as it looks really funky in the rack with the Sansamp RBI and Korg Racktuner (with matching blue lights) which satifies my OCD completely!

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