| Author | Message | ||
| davekoch
Junior Username: davekoch Post Number: 11 Registered: 1-2003 |
I need advice. I'm getting an F-1X preamp. Now I need a power amp. Lord Valve has good deals on new QSC PLX power amps, so I'll probably buy it there. Anyone have a used PLX 1602 or 2402 for sale? The PLX 1602 bridged would push 1100 watts into my Eden 4x10T (500-watt cab). But in stereo, the PLX 1602 would push only 300 watts into the 4x10T. Is 300 watts too little for the 4x10 500-watt cab? For the Eden 2x10T 250-watt cab (which I don't use all that often anymore), 300 watts is fine, right? If I went with the PLX 2402, it has 425 watts a side at 8 ohms, but 1500 watts bridged. Should I be hesitant about pushing 425 watts into a 250-watt cab, and/or pushing 1500 watts bridged into a 500-watt cab? PLX 1602 bridged at 8 ohms - 1100 watts stereo per side at 8 ohms - 300 watts PLX 2402 bridged at 8 ohms - 1500 watts stereo per side at 8 ohms - 425 watts My (older, white background/red logo) Eden cabs are both 8 ohms: 4x10T 500-watt 2x10T 250-watt The 2402 is $170 more than the 1602. I don't want to buy too much power, or not enough. Guys, I need some advice here, Thanks soooooo much, Dave (Message edited by davekoch on October 26, 2004) | ||
| davehouck
Senior Member Username: davehouck Post Number: 955 Registered: 5-2002 |
I would suggest you go with the 2402. The PLX has output controls for each channel. So you can run one channel full into the 500 watt cab; and on the other channel, back of a click or two for the 250 watt cab. I would not think you would want to run either amp bridged into those cabs. Also, by going with the 2402, you give yourself more options for the future. | ||
| shakeyeraz
Junior Username: shakeyeraz Post Number: 46 Registered: 11-2002 |
What Dave recommends makes sense. I have almost the exact set up with the 1602 and 2 4X10 Eden cabs, each 8-ohms. One is a 410T, the other is an XLT. I now have an Aguilar 659 preamp but previously had an F-1X. When I played in a classic rock band I used both cabs and the 1602 bridged was plenty of power to get over the top of the guitars - they were loud - so no worries on the power there. Now that I'm doing the blues/jazz band I rarely use both cabs together - I don't need the volume but I still run the QSC in bridge mode driving an 8-ohm load. The sound is clean from the low B on up and the QSC runs cool and quiet. One thing I did learn about the QSCs is the configuration for bridge mode works better with most preamps when the parallel channel switches are set to 'off' - i.e. not parallel. You'll see this when you get yours. Parallel mode 'on' bridges the two channels and, more importanly, changes the impedance that the preamp sees which can change the sound. I didn't know this when I had my F-1X so I don't know the impact there but with my Aguilar it definately makes a difference in the sound. Check out talkbass for more QSC info. Bob from QSC hangs out there and responds to inquiries - he is extraordinarily helpful and a great guy to talk with. BTW - I purchased my 1602 pre-owned for $400 k | ||
| davekoch
Junior Username: davekoch Post Number: 12 Registered: 1-2003 |
Am I interpreting these posts correctly? "davehouck" recommends the 2402 running in stereo mode (with 425 watts per side), right? I should avoid bridge mode in any configuration with my cabs. This would underpower the 4x10 - 500 watt cab and overpower the 2x10 - 250 watt cab, right? "shakeyeraz" recommends the 1602 running in bridge mode (delivering 1100 watts into the 4x10), right? This would overpower the 4x10 - 500 watt cab (1100 watts into), right? I wouldn't use the 2x10 in bridge mode. In stereo mode, the 1602 would deliver 300 watts into the 4x10 and 300 watts into the 2x10. How about underpowering vs. overpowering (reasonably, of course) speakers. I mostly use the 4x10 alone. Only a few gigs a year require using both the 4x10 and 2x10 together. (Maybe I should just sell the 2x10 - this would make the power amp decision a lot simpler, huh?) Dave | ||
| shakeyeraz
Junior Username: shakeyeraz Post Number: 47 Registered: 11-2002 |
I was just sharing my configuration - if I could have gotten the 2402 at the time I was looking I would have purchased that one but the 1602 was a good deal and it turns out that I'm happy with it. In general underpowering is not good - too much stress on the amp and leads to premature failures. Not to mention distortion and other signal mangling. Having more power than you need generally gives you transparancy (sp?) with the power amp which is what I prefer. This is why bridge mode, though it looks like an 1100 watt monster, really provides ample power for either of my cabs with sufficient headroom. I run the volume at 1 o'clock which is just over half-way - it's probably not a linear scale but gives you an idea of how I'm using the amp's power. IT always runs nice and cool. Remember too, everything in the signal path is important - use heavy gauge speaker cables and high quality interconnects between preamp and amp. Bottom line is always that you need to try it to confirm that this is what you're looking for sound-wise. | ||
| davekoch
Junior Username: davekoch Post Number: 13 Registered: 1-2003 |
Hi shakeyeraz, Thanks so much for all the information. I hope I didn't misrepresent your views; if I did it wasn't intentional. Eighty percent of the time I use just the 4x10. So in your opinion, would delivering 1100 watts into a 500 watt cab be OK? What are the power ratings on each of your cabs? One more thing. Does bridge mode "sound" different than stereo mode? If so, can you describe the difference? "Parallel mode 'on' bridges the two channels and, more importanly, changes the impedance that the preamp sees which can change the sound. " Thanks again. (Message edited by davekoch on October 26, 2004) | ||
| davehouck
Senior Member Username: davehouck Post Number: 957 Registered: 5-2002 |
I do not have a great understanding of electronics; and what I do learn, I do not retain in memory. There have been some very detailed discussions of this subject before in our group; and a good search should find them. Kevin says he has his gain control set at 1:00. With the gain control set at max, the PLX amps are increasing the input voltage 40 times, or 32db's. At 1:00, Kevin's amp is increasing the input voltage 24db. So, no, Kevin is not sending 1100 watts to his 4x10 unless he is seriously overdriving the input stage of the amp. Of course, if he were to decide to turn the gain control to full and slap the stings hard with the palm of his hand, then he could cause some damage. | ||
| davehouck
Senior Member Username: davehouck Post Number: 958 Registered: 5-2002 |
Here's a previous discussion on the subject: http://alembic.com/club/messages/449/7204.html | ||
| shakeyeraz
Junior Username: shakeyeraz Post Number: 48 Registered: 11-2002 |
I haven't tried stereo mode with the Aguilar so I can't comment on the impact of the impedance in that mode. If it did (does - I'll try this at some pont), I would certainly keep it in bridge mode. Daveh sums up the QSC/PLX operation perfectly - just to reiterate and IMHO, getting more power than you need is better than underpowering. | ||
| davekoch
Junior Username: davekoch Post Number: 14 Registered: 1-2003 |
1. Using the PLX1602 bridged with only the 4x10T (500W), would 1100W be too much power for the 4x10 cabinet? One guy at QSC mentioned that 500W RMS has about 1000W peak capacity. So, to prevent smoking the cab with 1100W, could I just not turn up the power amp as high? 2. Can the power amp be modified to reduce the power output? Other thoughts? (Message edited by davekoch on October 29, 2004) | ||
| gare
Member Username: gare Post Number: 80 Registered: 11-2003 |
I think something that should be considered is how amps are rated. How many different ratings are there ? Rms, peak, peak to peak, etc. The true output gets lost . If you say take an SVT tube head rated at 300 watts, what equivalent power would you need to match it in a solid state amp ? Whats actually a true power rating ? Ever stand in front of a cranked up 100 watt Marshall stack ? (I understand the frequency differences), but its LOUD. I think the manufacturers advertising has become a numbers game. And,like Shakeyeraz says, you're better off running more power than you need,you can run the preamp at a lower setting eliminating some noise and distortion for a cleaner sound. | ||
| davekoch
Junior Username: davekoch Post Number: 15 Registered: 1-2003 |
My main question that remains is: Using the QSC PLX1602 bridged with only the 4x10T, would 1100W be too much power for this 4x10 500W cabinet? We could talk Specs all day, but in the end, it's how does it sound? As long as no clipping occurs, no damage done to the speakers, right? Actually I couldn't talk Specs all day,  , I don't know enough about them. Sorta obvious, huh? (Message edited by davekoch on October 29, 2004) | ||
| davekoch
Junior Username: davekoch Post Number: 16 Registered: 1-2003 |
Thanks to all of you who shared their thoughts, experience, and advice. I decided on and ordered the PLX 1602. I'm excited!! Can anyone recommend a particular type, brand, or specs (gauge, plugs, etc.) for the cable(s) used to connect the F-1X to the power amp? Shorter the better (for 1/4" unbalanced), right? Anyone using, if possible, the balanced out? Recommendations? Thoughts? Dave | ||
| davekoch
Junior Username: davekoch Post Number: 18 Registered: 1-2003 |
TOTAL BUMMER. I received my new PLX 1602 and practically new (3-years old, but yes it's used) F1-X. The system doesn't work. With and without (plugging directly into PLX) the F1-X, the volume is VERY weak. It's about half as loud as my 35-watt Peavey Minx - I couldn't gig with this combo. Lord Valve (who sold me the PLX 1602) says it's a F1-X issue. He says going directly into the power amp will not be loud at all because there's no preamp to boost the signal strong enough so the PLX can utilize it's 1100 watts. Is this true? My bass has an onboard J-Retro preamp and with all Treble/Mids/Bass turned all the way up, it barely makes a difference. The F1-X seller says the F1-X worked perfectly before he shipped it. Should this gear work right out of the box? Does the F1-X and/or PLX 1602 need to tweaked to work with one another? My gear: Modulus Jazz with an onboard J-Retro preamp - produces a very hot signal!! Eden 4x10/2x10 cabs. I've verfied the cords all work. Suggestions? HELP................???? I'm totally frustrated!! | ||
| godoze
Junior Username: godoze Post Number: 48 Registered: 10-2004 |
Uh, the F1-x is a preamp is it not ? that answer makes no sense to me... | ||
| davehouck
Senior Member Username: davehouck Post Number: 1018 Registered: 5-2002 |
First test the F-1X. Plug the bass into input one. From the full range output, plug into the power amp input of the Peavey. This should tell you if there is a problem with the F-1X. Next test the PLX. Plug the bass into the Peavey. From the preamp output, plug into channel one of the PLX. Set all of the DIP switches ON except for number seven which should be OFF. This should tell you if there is a problem with the PLX. | ||
| davekoch
Junior Username: davekoch Post Number: 23 Registered: 1-2003 |
Thanks to all of you - bless your hearts!!! Mica was right about the Effects Loop jack - it was actually bad and needed to be replaced. It was barely getting a very, very weak signal. Jeff Krumm at Savage Audio, who designs and builds the Savage tube guitar amps, did the repair. He is a very competent audio guy, I trust him, and a great guy to boot. He did work for The Who when they were last in town. BTW, Jeff mentioned he's very impressed with the F-1X design, sound, and construction. He's worked on them before. So, he verified both the preamp and power amp, so all the gear is up and running. I feel good about it. However, the guy that sold me the F-1X maintains that it worked before he shipped it to me. Hmmmmm. Anyway, it works like a champ now, and I already love it. The sound of this rig is so very, very clean and warm. The response is just great. I've noticed posts about the Bass/Mid/Treble knobs affecting one another. Is there a guide or some recommendations on how they affect each other, or is it just trial and error? Any other information about using the F-1X that would be helpful? As for the out-of-phase issue, is this a big deal? In Stereo mode and using Full Range and High Pass output jacks, what actually happens? Can it cause damage to the gear? What's the fix - reversing the polarity on a cord, etc.? If I use Parallel mode, it wouldn't be relevant, right (as I'd be just using the Full Range output jack, sending the same signal to both channels of the power amp)? Does Stereo mode sound different than Parallel mode? To all who held my hand through this ordeal, thanks for all your help and concern. I've always heard great things about Alembic Support, and now I'm a believer. But the knowledge and concern on this forum is simply amazing. WOW - you guys are real pros, very smart, and perhaps even more importantly, nice people! I've wanted this preamp for many, many years. I don't play out as often anymore, as my wife's health is failing. I'm a caregiver now (severe diabetes, kidney transplant, and many, many other issues). But now I'm so excited about this gear. Thank you!! Dave | ||
| effclef
Advanced Member Username: effclef Post Number: 268 Registered: 1-2004 |
Dave, out-of-phase won't damage anything except your tone. ;-) When two speakers are out of phase, the sounds will cancel at the listener's ear. This is especially pronounced at bass frequencies! Thus the warning - I'd modify a cable or reverse the spade lugs as was suggested. I'm sorry to hear about your wife. But remember, music can be therapy for you, too, to keep you positive through the tough times. EffClef | ||
| davehouck
Senior Member Username: davehouck Post Number: 1025 Registered: 5-2002 |
>> "I've noticed posts about the Bass/Mid/Treble knobs affecting one another. Is there a guide or some recommendations on how they affect each other, or is it just trial and error? Any other information about using the F-1X that would be helpful?" _________ The following is taken from an article by Mark Gavin. _________ "Fender-style controls are used by many amp manufacturers because most guitarists prefer treble and bass boost (which is to say they prefer midrange cut). The Fender-style tone stack CANNOT provide treble or bass cut (in other words, no true mid boost). One way to regard boost circuits is that all frequencies are attenuated--then that attenuation is cancelled for a range of frequencies. The amount of broad-band attenuation is called insertion loss, and is a necessary evil of any circuit that provides a boost. The standard Fender midrange control does not really boost just the midrange--it boosts ALL frequencies. In other words, it decreases the insertion loss. This is why the value of the midrange pot cannot be increased much past 10k or so: it will render the treble and bass controls ineffective. This is perceived as mid-boost because it does cancel some of the midrange cut, but it cannot be a true boost because there is no way for the mid control to elevate midrange levels any higher than bass or treble levels. In fact, increasing mid control will actually boost the bass and treble a bit." ___________ To visually see how the tone controls interact with each other, go here and download the Tone Stack Calculator: http://www.duncanamps.com/tsc/index.html Choose the Fender tab. The values should be as follows; double click on any value to change it. (I believe these are the correct values for the F-1X; if not, please correct.) Zsrc = 38k R1 = 100k C1 = 250p C2 = 47n C3 = 100n R2 = 250k R3 = 250k R4 = 10k R5 = 1M (Initial post was incorrect, I had the wrong file open!) (Message edited by davehouck on November 17, 2004) | ||
| davekoch
Junior Username: davekoch Post Number: 24 Registered: 1-2003 |
EffClef, thanks for the kind words. I totally love her so I'm happy to care for her. Yes, playing music is therapy to me too - it is amazing in that respect. She's been a little better this past year, so maybe I can play out a little more. I'm hoping.... As for modifying a cable, it's only relevent in Stereo mode when I use two poweramp-to-cabinet cables, thus using both the Full Range AND the High Pass jacks, right? So there's no out-of-phase issue with Parallel mode, right? A pretty tech-savy guy told me that using Parallel mode would be just fine because even my Eden 2x10T cab can handle lows quite well and it matches up nicely with my Eden 4x10T - the coupling thing, I guess. Exactly what do I tell the guitar tech to do to modify a cable? My preamp-to-poweramp cords have 1/4" plugs on both ends. Both my poweramp-to-cabinet cords have one banana plug and one 1/4" plug. In Bridge mode, I connect the banana plug into the poweramp (straddling the 2 channels) and the 1/4" plug into the one cabinet. In Stereo mode, I would connect the banana plugs into each channel of the poweramp and connect the 1/4" plugs into each cabinet. Perhaps to have a backup cord, I should get a new cord made? Or would you suggestion I modify one of my existing speaker cables? Suggestions? Is Stereo mode preferred over Parallel mode by most players? Sound different? Would Stereo mode necessitate I use the Crossover with the High Pass output. If so, I'd connect High Pass output to the Eden 2x10T to reduce some of low frequencies, as it doesn't handle the lows like the Eden 4x10T. If the Crossover is required, what frequency would you set it at? | ||
| davehouck
Senior Member Username: davehouck Post Number: 1026 Registered: 5-2002 |
>> "As for modifying a cable, it's only relevent in Stereo mode when I use two poweramp-to-cabinet cables, thus using both the Full Range AND the High Pass jacks, right?" Right. >> "So there's no out-of-phase issue with Parallel mode, right?" If you are running just one cable from the full range output of the preamp, no cable from either the High or Low Pass outputs, then right, there is no out of phase issue. >> "A pretty tech-savy guy told me that using Parallel mode would be just fine because even my Eden 2x10T cab can handle lows quite well and it matches up nicely with my Eden 4x10T" That seems reasonable. >> "my poweramp-to-cabinet cords have one banana plug and one 1/4" plug" You don't need to modify the cable. Simply reverse one of the banana plugs when you plug it in so that the tab side is inserted in the wrong binding post. >> "Is Stereo mode preferred over Parallel mode by most players?" I use parallel mode. I run one cable from the F-1X full range output to the PLX; and thus, in parallel mode, run both cabs full range. I think this a more efficient use of the cabs. Since your cabs probably do not have a significant difference in low or high end tone, then as far as tone is concerned there is probably no advantage to using both the full range output and the high pass output and running the amp in stereo mode. >> "I'd connect High Pass output to the Eden 2x10T to reduce some of low frequencies, as it doesn't handle the lows like the Eden 4x10T." In this case, don't forget to reverse the tab on the banana plug when you plug it in. >> "If the Crossover is required, what frequency would you set it at?" You may find that you will vary the crossover frequency depending on the room. The accoustics of the room and the type of floor significantly effect the low end coming from the cabs. So you can view the crossover frequency as another tone control. | ||
| davekoch
Junior Username: davekoch Post Number: 25 Registered: 1-2003 |
"You don't need to modify the cable. Simply reverse one of the banana plugs when you plug it in so that the tab side is inserted in the wrong binding post." So that's all it is? Cool, I think I can even handle that.... Dave, thanks so much for clearing all this up. I am truly grateful. |
