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Everything posted by agedhorse

  1. With all 4 MOSFETs, it was capable of greater power into both 8 ohm and 4 ohm loads. There were many versions of these amps that used a similar output section, but it depends on the power transformer (thus the rail voltage) also. If the rail voltage gets too high (to achieve greater power into 8 ohms), then 4 output transistors may not be enough for the resulting higher power into 4 ohms. There were also different MOSFETS used throughout the production history, including special "double-die" parts. Over the years, there were some output stage applications that weren't all that reliable, and sometimes incorrect transformers were fitted in order to ship amps. Many of these unrelaiblities could be traced back to the liberal build philosophy rather than the circuits themselves.
  2. The AH-100 links are for manufacturing to use this PCB assy. with a different model. This amp, from the photo, uses a single pair of output MOSFETS. Depending on the power supply (rail) voltages, it may very well be rated for 8 ohms minimum load only. Especially because it has a single speaker jack in what was a combo, and because Celestion confirmed that it was an 8 ohm driver.
  3. You are going to need to do more testing and troubleshooting. There may be a small difference in DI level between the two different amp models, but not a huge difference.
  4. The later BLX-80's were rated for 4 ohm use and had a larger heatsink. There is no output transformer in the amp, so that part can't be part of any discussion. There were earlier versions of this amp, and there was indeed a version that was 8 ohms only, I believe it can be identified by having only 2 output transistors rather than 4, but my documentation is not entirely clear on this. It was not uncommon for Trace to have several versions of any model, making is more of a challenge to support. This appears to be part of the company culture, as I have had 2 supposedly identical models side by side on the bench and they were entirely different internally.
  5. The ground lift switch can't change the level. By any chance could the mic/line switch be set to the line position on the louder amp?
  6. Note that virtually all of the Chinese IcePower 125ASX2 modules being sold on eBay are counterfeits. The original manufacturer of your amp should be able to supply the part, though many will only supply them to authorized service facilities.
  7. There are indeed more variations than there are what you have suggested. As a generalization, most effects loops (also called insert loops) are serial and operate at line level. Most are post eq, but there are some that are pre-eq also. The normal routing switching is almost always done within the effects return jack. There are line in jacks that are usually called 'AUX IN", they provide a line level input sums with the main signal path. Line outputs are usually the same as the effects send as described above. Most XLR outputs start out as pre eq, balanced, mic level and add switched options such as mic-line level, pre-post eq routing and pin 1 ground lift. Of course there are exceptions, but the above is by far and away the norm.
  8. The circuitry that's used within the deep voicing, the entire voicing circuitry and compression are done very differently between the M3 and the M6/M9 (and there are differences between the M6 and M9 too)
  9. I've tried already on "the other" forum. The voicing is done differently on the M3, it's different from the M6 & M9.
  10. Agreed, when using any soft case with any amplifier, you do need to be careful when you and especially when others are handling your gear. This problem is not unique to the Subway amps, we see it on all brands and models but on the heavier models the damage tends to be more obvious (and more costly to repair). Glad you got it resolved, Westside has a very comprehensive and capable service department.
  11. You can use a 1/4" (6.35mm) female barrel connector and a short 1/4" (6.35mm) cable to extend the existing cable on the WA cabinet. It would be good practice to include an insulating tube over all conductive parts of the shell to prevent noise from ground loops. This advice is specific to the Walkabout which has a ground referenced speaker output. Some conventional amps and many class D amps use a bridged output topology, so because the shell is energized, the shell MUST be insulated from anything and everything that it might come into contact with.
  12. Bill - the Walkabout platform was designed before that point in time (~1999), and simply remained a legacy product many years longer than anticipated. There are 3 separate and distinct issues regarding the adoption of SpeakOn jacks within the international market. The first one was the possibility of a banana connection being too close to some AC power connector dimensions, the second is that with many bridged amps the open circuit voltage on the shell of a 1/4" connector would fall out of the range of the various low voltage directives and the third being that with high powered amps even the single ended voltage on the tip of the plug would fall out of this range. Some of this was later addressed with the the changes incorporated in IEC60065 section which allows higher voltages for audio speaker level signals BUT some jurisdictions will not allow this hence the almost universal migration to SpeakOn as the easier (and better) method of compliance globally.
  13. The 170 volts that I stated was for the 8 ohm example that you gave, I was simply following up on those numbers you gave. The 4 ohm value would be 340 watts, BUT you have to subtract about 2 volts (probably a bit more than this) for Vce(sat) from each rail (because it can't swing fully rail to rail) and because of the emitter resistors you have to subtract for that as well. Presumably, you have the module that has 4 bipolar output transistors (which is actually the 300 watt module, remember what I said earlier that these modules got mixed and matched with various transformers in order to ship products) because if you were really able to get 10 amps RMS which is 14 amps peak, you would have destroyed a single output transistor as soon as the output transistor got hot and the SOA derating kicked in (at right around 10 amps with these circuit voltages) So with each transistor handling 7 amps peak, and the emitter resistor being .22 ohms, the additional voltage drop of 1.5 volts applies (it would try to be 3 volts if it was a single output transistor). Now, doing your calculations on real world numbers, your output under load conditions is based on 56V - 2V - 1.5V = 52.5V, now divide this by 1.414 and your maximum RMS voltage is 37 volts RMS, which is 342 watts, which agrees closely with my prediction above. These are transient, ideal values (in RMS terms) that will be lower in practice because we didn't account for peak IR losses in the transformer, and other smaller factors. Now there are a couple of other possibilities, the first is that you really have a GP11-AH150 which uses MOSFET outputs and does have 2 pair per rail (one pair just didn't work out well, found that out early on for the reasons I mentioned above), which should have about the same performance as the bipolar example above (which is for the 300 watt/4 ohm rated module). The other possibility, and the one that I THINK is responsible for both your confusion as well as my confusion, is that this amp (with either the bipolar or MOSFET module) is rated at 150 watts RMS with a minimum load of 4 ohms in the marketing materials. In the production service docs, the test values given vary from 250 to 275 watts depending on the module and version. The 150 watts, I will agree is a very conservative number IF you consider that it's really a 250 - 275 watt/4 ohm rated amp by the designers/engineers BUT also confusing for nomenclature because they changed their module model numbers from 4 ohm power value from the bipolar series to the 8 ohm power value in the MOSFET series (and even this wasn't consistent depending on the particular documents). As an engineer, I spent a lot of time reviewing TE documentation and designs while working for one of the companies that owned Trace in a previous incarnation. There were a lot of really cool things about the designs but there were a lot of things that did not make sense from model to model or even build to build for the same model. This sort of thing is one example, and it was at the very core of the company's personality. So, in a way we are both right and wrong, for different reasons
  14. 112V peak to peak calculates to ~170 watts (RMS) not 264 watts. Once you get the math correct, you will find that your argument falls apart. You simply can't get 400 watts transient (in RMS metrics) with a pair of 56 volt rails. It's not that I don't believe you, but it's simply impossible.
  15. Sir, the scrap you got yourself into (with me) was of your own doing so let's be accurate here if you are going to claim something that's not true,. It is categorically impossible for your 150 watt (RMS) Trace amp to deliver 400 watt (RMS) under transient conditions, there simply isn't the supply voltage present to make this happen no matter what. I also pulled my product data for that amp and it supported my statement and the math I presented. Perhaps you forgot the part where I had worked for the parent company of Trace and was familiar with the amp? Now, you choose to change the argument or the scenario and consider power at "square wave clipping". (note that I have mentioned many times on that other forum that an amp (any amp) can deliver almost twice it's rated undistorted power when driven deep into clipping because that's an often unrecognized cause of damage of speakers due to overpowering). This is not "transient" power, or "headroom", or anything even remotely useful except to save face. Is is a great amp? Sure it is, no problem with that. Will it deliver 400 watts RMS even under transient conditions, no way.
  16. You are most welcome. I think there may in fact be a segment of the market that does conform to this consumer electronics mentality model. From what I have seen, these are generally companies where price is the biggest feature but I'm sure there are exceptions as well. I personally do not care for this model, it goes against 40+ years of engineering training.
  17. There are (understandably) a lot of misconceptions about this topic, so let me clarify a few things based on actual facts and data rather than internet folklore and perceptions. I looked at the statistics for last 100 class D amp repairs that came through the factory service program (this is for the Genz Benz brand) and found that there were only 6 that needed a replacement module. For the 600 watt class D module, the cost to the customer was $150 USD and the labor for the entire repair (everything else that might have been wrong plus any updated installed) was $75 (USD) flat. So worst case, the cost of the repair INCLUDING a new module was only $225 (USD). For the remaining 94 repairs, 92 cost only $75 (USD) and there were 2 basket cases where either a shop or end user got into the amp and did more damage than covered under the repair program pricing. Even the worst case scenario is generally less expensive than replacing an output transformer, a set of tubes, etc. Turnaround time on all but the 2 basket case repairs was 48 hours also. That said, there certainly are products that are built with no thought towards repairing them. This is much more often seen at the lower end of the market, not an area that I have a lot of experience with. Perhaps this discussion is more like "you get what you pay for" rather than the technology itself, as the same is true for solid state linear output amps (class AB/G/H). What percentage of failures in these amps involve the output section (certainly higher than 6%) and how many of these could be repaired for $75 flat (or even $225)? Of course I can only provide information for the North American market, and only for factory level service where there is no issue with knowledge, skill, professionalism and parts availability, but I can't see how it would be much different for other manufacturers either. Now one disturbing trend I have been seeing over the past 5 or so years is that non-factory service centers have become more and more of a challenge, the quality of techs has declined significantly, the turnaround times have become excessive (IMO, there's no excuse for an amp repair to take 6-8 weeks) and even more worrisome is the new trend of taking an amp in and taking a cash deposit, then doing an estimate (without ever troubleshooting or testing or performing any diagnostics) for an excessive amount of money knowing full well the customer isn't going approve the repair, then keeping the estimate fee. There was a shop I dealt with for a customer that appeared to survive off of estimate fees only and never did any repairs. IMO, this is wrong and borderlines on fraud. So, it's not the technology itself, but how the technology is implemented and the philosophy of the company supporting their products that really dictates the ability to economically repair an amp. I hope this helps explain more completely and accurately this topic.
  18. How is this ANY different than replacing the power amp module in a class D amp?
  19. Sorry, I missed this, even though the "notify" box is ticked. Noise like this can almost always be traced back to noise entering the system. It may be EMC, becoming more commonly encountered with all the new bootlegged (uncertified) LEDs and consumer electronics from China (mostly). The amount some of them can emit is staggering. Sometimes, this can be caused by a cell phone very close to the pickup or the amp but this is probably less common now. One thing that can help is to be sure that the amplifier is powered by an earthed circuit. The earthing conductor aids in EMC control to a large degree.
  20. I suspect that a big portion of the cost is in shipping the driver to the UK. I just looked up the cost of shipping and even if it fits in a Priority Mail large flat rate box (the least expensive way to ship to to be UK), the shipping cost is ~$100 USD (77 GBP). There are still import duties, paperwork and such. Deduct this from the price you were quoted and the cost of the driver isn't quite so bad. Priority Mail International® Large Flat Rate Box USPS-Produced Box: 23-11/16" x 11-3/4" x 3" or 12" x 12" x 5-1/2" Maximum weight 20 pounds. Select a Delivery Option Expected Delivery Day Retail Click-N-Ship® Normal Delivery Time 6 - 10 business days to many major markets $94.25 $94.25 There are 4 different drivers that were used in the PH series, if you are looking for the 8 ohm version, the only one still available is the latest revision and it's a cast frame driver so that may be part of the cost. You can always calculate out for new drivers, but they won't sound the same as the originals so there's a bit of a gamble there. If you do install different drivers, it's common courtesy to disclose this to the buyer when you sell the cabinet.
  21. Due to safety certifications and regulations, IcePower modules are not allowed to be repaired. Since the primary circuitry and all of the associated safety components are part of the integrated module, once the module is worked on the manufacturer's safety certification is no longer valid. As part of the manufacturing and testing process, an extensive number of automated tests (including safety certification tests) are performed on the module and the test result data is logged to the serial number of the module. I don't know of any service centers that have the equipment or knowledge to perform and certify these tests with a Nationally Recognized Agency. It turns out that because of the level of complexity and the specialized nature of the equipment and experience required to CORRECTLY diagnose and repair these modules, it's almost always less expensive to replace them than it would be to repair them. Even IcePower themselves doesn't repair defective parts returned to the factory under OEM warranty, it's less expensive to replace even though they have the necessary test equipment, knowledge and ability. The labor cost (including re-certification) is more than it costs to build. I don't like the concept anymore than you guys do, but when it costs more to repair than replace, it's hard to argue with reality so recycling the defective part is really the best solution.
  22. Give Westside another call, they will help you out. If you still can't get hold of them, let me know and I will follow up. They may be backed up a bit preparing for the new regulations that are taking place due to Brexit as this is "uncharted territory".
  23. Hissing, especially when it's present on both channels, is unlikely to be the tube (valve). The recommended valve for this amp is a 12AX7A (the AC5 is a selected/graded version, selected for lower noise and lower microphonics). In this circuit, its life expectancy is over 20 years (I designed this amp, so I have a pretty good point of reference here) and I have diagnosed only one defective tube in the last 5 years of the factory service/support program. These amps have a low noise floor, and have been a very reliable with no known issues over the past 10+ years. Before getting too deep into this whole tube thing, the very first thing I would recommend is systematic troubleshooting. Specific things to eliminate as possible causes external to the amp are: 1. Is the amp quiet without using any pedals? The most common cause of noise is from pedals, especially compressor pedals. All of the noise generated internally by pedals gets amplified by the amplifier, so a pedal that generates noise ultimately defines the noise floor because this noise is amplified by the total gain of the amplifier. Compressor pedals are especially suspect because the gain reduction circuit (called the gain cell) in the pedal works by starting out with a higher gain under low signal conditions and then reducing the gain as the signal level increases. For every dB of gain cell reduction, this adds a minimum of 1dB of noise to t he noise floor. It's intrusive because the worst noise floor is when there is no signal. This is why high quality pro audio compressors invest so much cost into lower noise circuitry and VCA's, the results are clearly audible. 2. If you are using a lot of treble boost, or if you have the tweeter attenuator all the way up on a cabinet that has an inefficient woofer section, this can make the noise of all preceding electronics appear noisier than they really are. If you are after a bright, in your face tone than this might be something you have to live with, or invest in a line level noise gate inserted into the effects loop. When using a gate, choosing the least amount of gate attenuation as possible to achieve the necessary noise floor improvement will help it sound and feel more natural. A 6dB gate attenuation will cut the noise power by 75%, so generally there is no need to use very deep cuts. 3. If you are using an active bass, be sure that your battery is good. Some active electronics packages can get very noise as the battery voltage falls. 4. If your active bass has eq built in, excessive treble boost can exaggerate noise within the on-board electronics which is then amplified by the amplifier. 5. Is the amp quieter with the tone shaping switches disengaged? Each filter can add a little bit of noise, especially the attack filter when a high amount of attack used. 6.With nothing plugged into your amp except the speaker, is the amp quiet with the channel gain, channel volume, master volume and eq all set to the 12:00 position? When switching between the tube channel and the FET channel, it's normal for there to be a just couple dB more noise in the tube channel. Where do you typically operate the controls? Hope this helps.
  24. I've been in this business for 40 years now. I remember when EVERYBODY (manufacturers, distributors, retailers, service centers) added tremendous value to the products they represented, sold and serviced. Call me "old school", but I still believe that all of these are important for good customer experiences. Of course, it's expensive for all of these businesses to stay current on the products and the technology and when the customer demands an ever-cheaper price, something has to give. The manufacturer gives up quality and has a shorter warranty, the distributor gives up training, knowledge and how many models they can stock/import, the retailer gives up how much they can stock, the level of customer service and what they are able to do to make the customer happy, and the service center finds themselves in the position of not being able to hire top notch techs with the necessary skills because the job pays less and less, which attracts poor quality techs who are simply in over their heads and take much longer to repair an amp than a skilled tech. As an example, there's no Subway amp that I can't fix in 1 hour, period. Same goes for any Genz Benz Shuttle or Streamliner amp. This means that the labor charge to fix it right is often less than what a hack tech charges for an estimate. In your case (UK), Westside puts forth a lot of effort in representing the brands they distribute. They know their stuff, have an excellent service department (as you discovered) and spend a lot of time following through when something isn't right. This doesn't come for free, nor should it IMO.
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