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Check It Out - Product Pics
- Thread starter jfiles
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Hi John,
I noticed a couple of these in different power configurations on the website. I have a question about them. Well, a couple of questions, followed by some "in print" stream-of-consciousness thinking (and I have ADHD!).
Is this a straight-up power amp? Or is it basically the 350W model without the equalization?
Either way, can it be run in a master/slave configuration with one of the more full-featured amps? SWR tried something like this with the AmpLite and HeadLite (albeit shortly before their demise), and I was actually very surprised the idea didn't take off. If you own a pair of 4-ohm cabs and land a spacious outdoor gig with (*ahem*) "questionable" front-of-house capability, it would be nice to not be limited to the steadily-diminishing selection of 2-ohm-capable heads...
On the other hand, it would be interesting to try a simple amp with just Gain and Master, then using either a bass's on-board EQ, or a pedal (some of them are starting to sound better than the tone-shaping circuits that some amp-makers are using in their heads) to tweak the sound...
This is a complete, albeit stripped down, bass amplifier. It has input gain, output level, a power amp, and a DI. It is a great pedal platform or if you have a bass with an EQ as you suggest. In the Hi-Fi world, we refer to this configuration as 'straight wire with gain'. This suggests that what you put in is what you get out of it (of course, there is no such thing as a completely transparent amplifier, so you will get some coloration). So, it is in between just a power amplifier and full-featured bass amp.
You mentioned a 2-Ohm capable head, please be aware that this is rated at 2.67-Ohms, not 2-Ohms (an 8-Ohm and a 4-Ohm or 3 x 8-Ohm speakers, for example). I don't know how it would work with 2 x 4-Ohms, but it is only rated for a minimum load of 2.67-Ohms.
Your opening paragraph asks if this is like a ONE350 without EQ, and yes, this is essentially what this is. I love the idea because I almost never use tone controls - I either use a different bass, use different strings or change my technique. I don't play in any cover bands or pickup gigs, so that makes my situation easier than some, but that's just my situation.
Let me know if you have any other questions or if I can help in any way.
Thanks! John
You mentioned a 2-Ohm capable head, please be aware that this is rated at 2.67-Ohms, not 2-Ohms (an 8-Ohm and a 4-Ohm or 3 x 8-Ohm speakers, for example). I don't know how it would work with 2 x 4-Ohms, but it is only rated for a minimum load of 2.67-Ohms.
Your opening paragraph asks if this is like a ONE350 without EQ, and yes, this is essentially what this is. I love the idea because I almost never use tone controls - I either use a different bass, use different strings or change my technique. I don't play in any cover bands or pickup gigs, so that makes my situation easier than some, but that's just my situation.
Let me know if you have any other questions or if I can help in any way.
Thanks! John
Hi John,
I don't think I quite articulated the scenario well. My thought was, if I have two 4-ohm cabs I want to use, but only have a head rated to 4 ohm or 2.67 ohm impedances, my thought was to use said head in a master/slave configuration with the product I was inquiring about in order to utilize the power sections of both amplifiers (but the tone-shaping governed by the Master head) to drive the two 4 ohm cabs, effectively creating a rig with scaleable power capabilities. Ashdown's Head of Doom is one of the more recent products to do something like this.
Judging from your reply, it doesn't look like what I outlined was the intent of this product's design, but rather as a "pedal platform" amp, which is a perfectly-valid product niche in its own right, especially when we consider some excellent pre-amp pedals from NYC and Finland!
Hi, You are correct, I misunderstood. I checked out the Head of Doom and wanted to see the manual, but I couldn't find one. I would like to know the impedance and voltage output of the 'slave outputs' on the HOD amp. The diagrams from Ashdown show one wiring scheme where the 'slave outputs' go back into the instrument input of another HOD. This suggests that the 'slave output' is not extremely hot, so it should be able to drive the input of the PureAmp 700x2 without overdriving the input stage. All the 'slave outputs' are is a line/signal output. Those have been on amplifiers since the '60s. We just need to verify the signal level.
If the signal level is OK, you could come out of 'slave A' on the HOD into channel 1 of the PA700x2 and 'slave B' of the HOD into channel 2 of the PureAmp 700x2. Use the input gains to get the signal level, and by not running them wide open allowing you to use them as a variable pad to keep the signal pure. You could then run speakers off of the HOD and also run: (2) 8-Ohm; (4) 8-Ohm; (2) 8-Ohm + (2) 4-Ohm; or (2) 4-Ohm speakers off of the PureAmp 700x2 amplifier. You would then have level controls to adjust the speaker sets independently if needed.
This will provide you with a scalable solution. You will effectively have (3) power amps (HOD 600w RMS @ 4-Ohms, PureAmp 700x2 Channel 1 700w RMS @ 4/2,67-Ohms & PureAmp 700x2 Channel 2 700w RMS @ 4/2.67-Ohms). This would not operate differently than any power amplifier, but with the advantage of a preamp section that you could use as a backup amp in a pinch.
Does this answer your question better and fit more exactly what you are thinking about? Thanks! John
If the signal level is OK, you could come out of 'slave A' on the HOD into channel 1 of the PA700x2 and 'slave B' of the HOD into channel 2 of the PureAmp 700x2. Use the input gains to get the signal level, and by not running them wide open allowing you to use them as a variable pad to keep the signal pure. You could then run speakers off of the HOD and also run: (2) 8-Ohm; (4) 8-Ohm; (2) 8-Ohm + (2) 4-Ohm; or (2) 4-Ohm speakers off of the PureAmp 700x2 amplifier. You would then have level controls to adjust the speaker sets independently if needed.
This will provide you with a scalable solution. You will effectively have (3) power amps (HOD 600w RMS @ 4-Ohms, PureAmp 700x2 Channel 1 700w RMS @ 4/2,67-Ohms & PureAmp 700x2 Channel 2 700w RMS @ 4/2.67-Ohms). This would not operate differently than any power amplifier, but with the advantage of a preamp section that you could use as a backup amp in a pinch.
Does this answer your question better and fit more exactly what you are thinking about? Thanks! John
Hi John,
Yeah, that about covers it. My biggest curiosity was if it was safe to run a line out from a head or pre-amp into the input of a GR Pure-Amp, and it sounds like it could be, provided the line out from the other head operates within instrument-level voltages.
Thanks for the clarification!
Yeah, that about covers it. My biggest curiosity was if it was safe to run a line out from a head or pre-amp into the input of a GR Pure-Amp, and it sounds like it could be, provided the line out from the other head operates within instrument-level voltages.
Thanks for the clarification!
Certainly, that's what I'm here for. If you find the specs for the output of the 'slave out' of the HOD and I will certify the match of running from it into the PA700 x 2. John
have to be perfectly honest...that logo is very cheesy and the fact that it's so largely displayed on the cabinet would keep me from buying one. Total eyesore.
Hi Adam, I appreciate your comments and your honesty. Not all designs are for everyone (I personally like it), but they do sound great. I suppose if you played one and liked it enough you could always remove the logo. Here's wishing you and yours a safe and happy holiday season! Thanks! John
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So when the specs state “4 ohms or 8 ohms,” does that mean you can order a cabinet with either a 4- or an 8-ohm rating, or is it just one model with a switch between 4 and 8 ohms?
No, you pick either 4-Ohms or 8-Ohms for the cabinet and the appropriate driver(s) are loaded into the box at the time of manufacture. The advantage for some players in choosing a 4-Ohm driver is to get the maximum output power of an amplifier rated at 4-Ohms (remember that doubling your power, say from 400w RMS to 800w RMS will only give you a 3db volume increase, so, it's not as great an advantage as it seems - it does, however, provide you with more headroom, which is nice).
If your minimum amplifier load is 4-Ohms, you may choose 1 x 4-Ohm cabinet OR 2 x 8-Ohm cabinets so you can run a pair (8-Ohms / 2= 4-Ohms). The advantage here is that you now have maximum output power and twice the speakers, so you will generate more acoustic energy (i.e. volume and room coverage). Of course, you have 2 x the speakers to carry and have spent 2 x the cost of a single speaker.
There are some speakers on the market with a switch, that don't really do what the suggest they do. Speakers with a switch either use; 1) a dual-coil woofer (you see these a lot in home hi-fi subwoofers) or, 2) will add an additional resistor/capacitor contraption on the input panel. The problem with dual-coil woofers is that you have more mass to move and more voice-coil for the signal to flow through, so you lose whatever efficiency you gained by going from a nominal 8-Ohm load to a 4-Ohm load. The same issue applies to having an additional resistor/capacitor to change the impedance. If lowering the nominal load on the amplifier doubles the power (and you gain 3db in volume), the dual voice-coil and/or resistor switching scheme usually costs you about 2.5db on average, so there is no real gain.
There are a lot of great ideas, but it's impossible to change the laws of physics and there aren't any shortcuts. If you know what your application is going to be it can help you make a decision. The GR Bass amps will run at a 2.67-Ohm nominal load, BTW. What that means is that you can hook up both a 4-Ohm and an 8-Ohm speaker at the same time (2.67-Ohms). This gives you more acoustic output and will allow you to use a single speaker (say you have a pair of 1-12" speakers) for a small gig and a pair for a larger gig. The drawback here is that the 4-Ohm speaker will be louder than the other speaker, so they will not be a perfect balance (the 4-Ohm will often play about 3db louder than the 8-Ohm version). If, however, the 8-Ohm cabinet is more efficient (by between 2-Ohms ~ 4-Ohms) you will have a pretty close match of efficiency when they are both hooked up.
As in all things audio, you will just need to listen to it to decide how it sounds after you have determined your needs. What makes you happy when you are playing is generally the right solution.
If I didn't explain this clearly or if you have more questions, please let me know. Thanks! John
If your minimum amplifier load is 4-Ohms, you may choose 1 x 4-Ohm cabinet OR 2 x 8-Ohm cabinets so you can run a pair (8-Ohms / 2= 4-Ohms). The advantage here is that you now have maximum output power and twice the speakers, so you will generate more acoustic energy (i.e. volume and room coverage). Of course, you have 2 x the speakers to carry and have spent 2 x the cost of a single speaker.
There are some speakers on the market with a switch, that don't really do what the suggest they do. Speakers with a switch either use; 1) a dual-coil woofer (you see these a lot in home hi-fi subwoofers) or, 2) will add an additional resistor/capacitor contraption on the input panel. The problem with dual-coil woofers is that you have more mass to move and more voice-coil for the signal to flow through, so you lose whatever efficiency you gained by going from a nominal 8-Ohm load to a 4-Ohm load. The same issue applies to having an additional resistor/capacitor to change the impedance. If lowering the nominal load on the amplifier doubles the power (and you gain 3db in volume), the dual voice-coil and/or resistor switching scheme usually costs you about 2.5db on average, so there is no real gain.
There are a lot of great ideas, but it's impossible to change the laws of physics and there aren't any shortcuts. If you know what your application is going to be it can help you make a decision. The GR Bass amps will run at a 2.67-Ohm nominal load, BTW. What that means is that you can hook up both a 4-Ohm and an 8-Ohm speaker at the same time (2.67-Ohms). This gives you more acoustic output and will allow you to use a single speaker (say you have a pair of 1-12" speakers) for a small gig and a pair for a larger gig. The drawback here is that the 4-Ohm speaker will be louder than the other speaker, so they will not be a perfect balance (the 4-Ohm will often play about 3db louder than the 8-Ohm version). If, however, the 8-Ohm cabinet is more efficient (by between 2-Ohms ~ 4-Ohms) you will have a pretty close match of efficiency when they are both hooked up.
As in all things audio, you will just need to listen to it to decide how it sounds after you have determined your needs. What makes you happy when you are playing is generally the right solution.
If I didn't explain this clearly or if you have more questions, please let me know. Thanks! John
