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Posts posted by agedhorse


    1 hour ago, Killed_by_Death said:



    spraying directly onto the plug & then plugging & unplugging

    yay or nay?


    This is generally fine. 

    Spraying into the amp usually gets incompatible substances where they don't belong, creating new and messier problems to deal with.

    • Like 1

  2. 16 hours ago, skidder652003 said:

    buy some servisol and give the inputs a bloomin' good spray!

    Good God I hope not, for the sake of the tech that needs to clean up the resulting mess at least.

  3. 6 hours ago, Dan Dare said:

    Unless it was a valve amp, probably just means they brushed the dust out of the vents and sprayed the contacts and sockets with switch cleaner.

    Sure hope they don't go spraying things down with "magic cure-all spray", I see plenty of gear damaged from such treatment. ESPECIALLY switch contact cleaners.

  4. Ok, that's a GB 410 standard, had to go back deep into the archives but it was a model from the mid to late 1990's and was shipped 8 ohm as standard with a 4 ohm optional version as well.

    I do still have a limited number of recone kits available for this model in both 8 ohms (standard cabinet, series-parallel wiring) and 4 ohms (optional cabinet, 16 ohm driver parallel wiring).



    • Like 2

  5. 11 hours ago, nilebodgers said:

    I seem to recall the Mesa chap that posts on Talkbass saying that their cabs are specifically designed to work together re. tuning / response etc.

    @agedhorse is who I meant.

    Yes, this is correct.

    • Like 2

  6. IME, most 300 watt RMS speaker that will handle this kind of power may be quite colored due to the heavier suspension and long wound voice coil (compared with gap depth) required for mechanical robustness. This results in significant high frequency rolloff compared with a full range or extended range design.

    • Like 1

  7. 5 hours ago, DiMarco said:

    Thanks for the responses guys. It is hard to find this kind of info if you don't know where to look.

    Do bass amp manufacturers state the instrument input impedances and is there a difference between passive and active signal inputs other then the level?

    Thanks again.


    Some but certainly not all manufacturers provide these specifications.

    Depending on the circuit topology, the input impedance may be different or the same between passive and active inputs. On the Subway amps, the input impedance is ~1M in both passive and active positions.

    The specifications for the Subway amps are located in the back of the respective owner’s manuals. 

    • Like 1

  8. 1 hour ago, Bill Fitzmaurice said:

    I think you've got that backwards. The load input impedance should be at least ten times the impedance of the source.

    This goes into greater detail than most of use need to know: http://whirlwindusa.com/support/tech-articles/high-and-low-impedance-signals/   The gist of it says ' In order to preserve signal level and frequency response, it's important to drive equipment with a source signal that is lower in impedance than the destination equipment's input impedance. If the input impedance of a device is not significantly higher than the source impedance, the signal will be reduced or “loaded down” and its signal to noise ratio and frequency response will suffer. '

    It depends. On a console the mic channel needs an additional gain stage because low-Z mics have very low output compared to a a high-Z guitar or bass pickup. But both have lower output than a low-Z line level signal.

    Yeah, I did kind of get that switched around ;)

    • Like 1

  9. In general, where the OUTPUT impedance of the SOURCE is less than 1/10th the INPUT impedance of the LOAD, the effects of loading can be ignored. If this is not true, it's possible for issues to occur. 

    This is independent of level, a different parameter entirely.

    [edit for garbled response, clearly reversed]

  10. 15 hours ago, itu said:

    Glockenklang Soul, 450 W, 2 x 10". 38 kg = 84 lbs!

    SWR has many nice sets and I suppose they are available in Canada. I might look for a head and a cab, as a similar combo is heavy! If 2 x 10" sounds good, a 2 x 12" would also be an option. Cone area is bigger than in a single 15" but not as big as a 4 x 10". Moves air. Soundwise I like a bigger box of a double speaker than like 2 x (1 x 12").

    Are you aware that SWR as a company has been shut down for almost 7 years and that there is no support available (including parts)?

  11. 8 hours ago, Chienmortbb said:

    Very True.To be honest the ASX range is very long in the tooth and is largely superseded by the AS range. To me the ideal module for the diyer is the 700AS1 from ICEPower 350W 8ohm, 700W 4 ohm and all the functions needed to make a modern amp easier to build. I believe that this amp is used in many of the "800 watt" amps of the last 3-4 amps. ICEPower seem to have controlled distribution of this model better than the lower power ASX modules. I suspect @agedhorse knows this module well but it is unfair to ask him about it.

    The ASX-2 models are long in the tooth, but they are actually still quite a ways better or more appropriate (all things considered) that much of the competition. That's why they are still being used in a variety of current products.


    With regard to rated power, there are different applications that exploit different aspects from all of these modules. That's one of the confusing things, where somebody looks at a data sheet or a marketing sheet and comes to a conclusion that simply does not apply for a particular application. I ran into this head-on when I designed an application around the 250ASX2 module that allowed the amp to operate BTL into 4 ohms even though the specifications stated 8 ohm minimum load in BTL mode. Initially, it was claimed that I was a fake, and that it was impossible, couldn't be done, would blow up, and couldn't deliver 900 watts RMS into such a load. This was from other amp manufacturers, as well as end users who hadn't even the slightest clue about amplifier engineering but were high and vocal on the bully pulpit.

    In the end, with ICEPower's support and approval, we received a patent for our approach and delivered many thousands of highly reliable amps based on this "impossible" platform. We were the first to use this part like this, and obviously others followed what we did with their own interpretations (some successful and some not). Some of the concepts behind the newer AS1 platform came out of the research and data that resulted from our off-sheet application of the ASX2 parts. I can't go into anymore on this.

    The short story is that there is more going on in many of these products than the average or even technically inclined person might ever imagine.

  12. ICEPower only sells OEM, that represents 99.9% of their business. That’s likely why it’s not worth the effort or the cost on an older product. 

    Those who buy a product like this on eBay from China, outside of the authorized distribution network, are getting what they pay for in the sense that eBay is well known as a marketplace for counterfeit goods. 

    Profusion is an authorized distributor for some ICEPower models, but yes they are more expensive.


  13. The genuine parts are more expensive to build, the test process is very comprehensive, the factory’s are more expensive to operate because they are under NRTL (nationally recognized test lab) inspections, and the products include international safety and EMC compliance which is also costly to maintain.

    All OEM’s who currently use this part are aware of the situation now, but the damage is done. Most quality OEMs buy directly from ICEPower so there is no issue with us receiving counterfeit parts as the tracking is quite thorough and serial numbered.

  14. 20 hours ago, Chienmortbb said:

     I should add that I respect @agedhorse's knowledge here. I used to think that they were all probably fake but was persuaded otherwise. However I suspect that there are few people on the planet that have more experience/knowledge  with class D modules that @agedhorse so if he says those sourced from the Far East are fake, I trust him.

    It is unfortunate. As a long time (as in almost the beginning of IcePower when they were financed and partially owned by B&O) designer of products using IcePower parts, I have access to much more information than most do. The backstory is complicated and confidential, but it was basically outright theft of their IP. Unfortunately it's hard (read as virtually impossible) to enforce anything in China, and there were some amp manufacturers that used of IcePower product that were tempted by the lower price of the counterfeits (most didn't realize they were counterfeits as they were marketed as surplus from a large Chinese contract manufacturer who got stick with thousands of these parts) only to learn that they were counterfeits and the reliability was nowhere near the same.

    Counterfeiting is a very real problem. I got burned once (about 20 years ago) when I ordered a National Semiconductor part from a reputable authorized National Semiconductor distributor. The parts didn't work the same, but they looked identical in every way. Sent them to the manufacturer for x-ray analysis and it turned out to be a different die inside the package with different characteristics. It turned out that a customer ordered many thousands of these parts and then returned counterfeit parts in counterfeit sealed packaging to the distributor (common practice) several thousand of the parts for credit. They were an expensive enough part that it was worth the hassle apparently. 

  15. On 06/03/2021 at 14:06, owen said:

    If abused, yes. But that does not have to happen. I used to bridge a Chevin A3000 into an Eden 4x10. The headroom was utterly addictive. 

    True until you have an accident, or a momentary lapse of good judgement. 

  16. The "gain factor" of a tube does not necessarily translate into circuit gain. It depends very much on the circuit itself. There are circuits where a tube with "higher gain" will result in a circuit performing with LOWER gain. It really does depend on the circuit the tube is used in.

    Forgive my use of the word tube in place of valve...

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