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Thread: Bgw amp plus eq for free!

  1. #466
    Senior Member RMC's Avatar
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    ANOTHER TOY TO PLAY WITH...

    While being at dealer's place for more Neutrik connectors and Rapco spkr cables, i purchased a used Direct Injection (DI) box. Dealer had an interesting model for cheap. Cosmetically it does show mileage, but everything used they sell goes first to repair tech dept for testing. There's various types and makers of DIs, Digiflex being a Canadian company i'd rather get one from them.

    For $15.CAD the DI is a pretty good deal, i probably have my money's worth or more just with the connectors on the unit. My interest was in getting a stereo one, not a more frequent mono. Its not the only stereo on the market, but others like Rapco or Radial Eng., more often have 1/4" inputs and XLR outputs. The Digiflex has two 1/4", one 1/8" stereo, and two gold plated RCA inputs, then XLR outputs, giving more input flexibility from various devices. This one could be more audiophile or playback oriented, than musician specific (still has 1/4" & XLR).

    It appears to be well made, built tough like most good DIs, the box connectors are protected, and its a relatively heavy unit at just over 1.25 LB. Approx dimensions are 5" L X 4" W X 2" H. The DI having rubber feet it won't scratch or slip on a surface, though one might use it vertically oriented on its side for space saving.

    According to Digiflex its made of high quality components and has Audiophile grade transformers. Haven't had time yet to try it. But it might become a lower cost, passive alternative to an Aphex 124A i use to balance turntable signal for e.g., or using a 1/8" stereo cable to feed my MD recorder in the DI then on to mixer, etc.

    Having checked this DSPDI carefully i'm not worried about the cosmetic, what matters most here is the connectors and the stuff inside that box, both of which are in good condition.

    BTW to all viewers here, i never expected this thread would ever reach a quarter-million views! Thank You. Have other things in the pipeline but not enough time these days, pretty busy for a while. So we'll see.

    Richard

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    Digiflex 2020 price list shown, DSPDI retail price now around $65.CAD

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  2. #467
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    Rocker switch is for ground lift, if need be

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    Gold plating on RCAs is better seen at the bottom of this pic

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  3. #468
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    Just keep in mind that a nominal -10dbm input on the 1/4" jack side of the DI will give you about a -40 dbm mic level XLR output side of the DI. Useful if you're feeding a recorder that has mic level inputs but not really a passive Aphex level convertor. Also those unshielded transformers don't want to be near any sort of power transformer.

    Quote Originally Posted by RMC View Post
    ANOTHER TOY TO PLAY WITH...

    ...
    According to Digiflex its made of high quality components and has Audiophile grade transformers. Haven't had time yet to try it. But it might become a lower cost, passive alternative to an Aphex 124A i use to balance turntable signal for e.g., or using a 1/8" stereo cable to feed my MD recorder in the DI then on to mixer, etc.

    ...

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    Digiflex 2020 price list shown, DSPDI retail price now around $65.CAD

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  4. #469
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    Hi Riley,

    Thanks for the output level reminder. However i don't anticipate any gain problem with the mixer XLR inputs. Mackie channel trim adjustment on XLR provides up to 60 db of gain. Then channel gain pot provides up to 20 db of gain. So there's a lot of gain in store, not counting the masters.

    Richard

    Mackie owner manual

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  5. #470
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    CREST AUDIO AMP MADE IT HOME TODAY

    Been looking at the small (1 RU) Crest Audio PA-150 Class A/B amp for some time. I don't really need it but its hard to say no to a good old Crest, made in the USA, not China. Looks in pretty good condition and was not abusively priced.

    Appears to be made tough and the little i could see inside seemed encouraging.

    Its quite heavy for its size, reminds me of the BGW 100Bs i had. But this Crest is about 20 years younger, and a more modern amp.

    I put the Crest on a scale and it showed about 17 lb, close to BGW 19 lb. Other small size amps i have (QSC, Tascam, etc.) weigh about 12 lb.

    Eager to hear how it sounds, though quite busy these days, hopefully will find some time to give it a good road test. Don't have time now for all the details but will be back later with more.

    Posting below the short features sheet at this time, and no you're not dyslexic if you read the amp provides the same 75W RMS at all impedances (4, 8, 16 ohm). Btw one shall NOT move the impedance selector at the back while the amp is on, it should be turned off (owner manual).

    Checking the amp upon getting it, it does turn-on so a good start, and i noticed a feature i don't recall being mentioned in the docs: seems to have turn-on delay and turn-off muting, which the BGW did not have...

    Small amp with a big heart, lol

    Richard

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  6. #471
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  7. #472
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  8. #473
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    The Crest Audio PA-150 is my first Crest and Commercial series amp also. I figured if that's what it takes to get a good used Crest amp then i'm game. Would not have purchased one from many other brands. Rear panel gain controls and barrier strip connections aren't really my cup of tea, but for this Crest amp its worth the compromise. Years ago a new PA-150 was a $595.US amp (retail) that some dealers discounted to $476. as i saw.

    The decision wasn't made in a hurry, did my homework. Then, getting a third party's feedback, specially from someone who repairs amps, could be helpful re reliability. So recently on my last visit to dealer i spoke with one of the senior repair technicians regarding the Crest inside story. He said we've been using Crest Audio amps for at least 20 years and they're not problematic amps (dealer also uses many Crown Macro-Tech and i-Tech type). Then he inquired about asking price and the unit's condition as seen on pics. Following my positive reply he said i wouldn't hesitate if i were you, go for it.

    Though getting the Crest amp means i bought myself a little work, connections wise. Had a few suitable cables i made in the past (1/4"TRS to barrier strip) however these are assigned to other equipment. I'm used to XLR and 1/4" TRS, as well as binding posts mated with banana plugs for speakers. Checked in my stuff and have all i need for the barrier strips wiring, with many different terminals. Simply needed to make new dedicated cable sets, with connectors and terminals to get going.

    For speaker wires i didn't want to cut some lengths now from my 12 and 14 gauge rolls that i may regret later having cut since i'm still in a temporary setup. Have a pair of 6-7 ft. 16 gauge cables that should do the job for amp testing purpose. I plan to use the largest terminals that will fit on the barrier strips, specially for speaker outputs, in order to minimize resistance and improving current flow to speakers.

    The Crest won't be in a permanent installation for a while, will rather be in my equipment rotation like others do. Commercial/installation gear can sometimes be out of direct sight, the operator not necessarily aware an amp is clipping. So the compression feature on this amp can be useful in preventing CD or tweeter burn-out for example. That feature seems quite logical and in line with the "set and forget" that commercial equipment often is. The show must go on...

    Have not shown pictures inside the amp, nor have i opened it yet, since seller put a sticker joining top and back panels to prevent amp tampering, because he provides a 30 day warranty/return privilege. If the seal is broken, then tough luck buddy. Therefore, after 30 days i'll be more than happy to remove the top cover, plus see among other things what makes it so heavy. Probably not the long heatsinks since these are Alu made, a relatively light metal. More coming.

    Richard

    P.S. Last night and again tonight spent hours listening to various CDs and LPs using the small Crest Audio amp. Sound is impressive, had not expected this much. It deserves to be on duty more often than its turn in my rotation: no days off! Will report on the listening tests in a coming post.

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  9. #474
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    CREST AUDIO AMP LISTENING TESTS

    Since my last post here, i did a third listening session with the Crest amp. The comments cover all three.

    This amp sounds really good. i was struck right at the beginning by the transparency and clean signal it offered in CD reproduction. Presence and detail are also nice. The mid and highs are possibly where it shines the most even though i found bass to be tight. The Crest beats the BGWs i had on sound, the latter having a more incisive top end for example. My Mosfet amps have a softer one, the Crest being in the middle with just the right highs. Globally one of my preferred sounding amp.

    In fact, being so transparent and clean i realized, looking at the output LEDs on the mixer, that i was turning up the master gain higher than usual, with consequent spl, and no listening annoyance. Seems easy to get ambitious on this amp's level. It was not due to amp gain requirements since it has the same (8 ohm) 1V RMS for full output spec, as other amps i have. While using the usual gear, the different component being the Crest amp.

    Using CDs i did note a little brightness, not to my liking, with the Tascam CD 200 SB player (balanced version). I don't recall having this with the other Tascam (CD 200 unbalanced) i have. To confirm if the amp or CD player was the cause, i switched to a consumer CD player i kept and played the same CDs with it. Didn't use the cheap RCA cables that come with these, but instead some nice Digiflex RCA, having twisted pair wires, with good connectors and RCA to 1/4" adaptors to connect in the same mixer channels (though unbalanced this time). No brightness heard at all with that player. Therefore the Crest amp is not the cause here, the balanced Tascam is. Solution is simple, high EQ (12 khz) on mixer at -2db or so gets rid of the brightness, peace restored. Apart from that brightness, the balanced Tascam sounds way better than the consumer player.

    With LPs (using Shure M95ED with an original stylus) the amp did not provide as nice sound as CDs, though results are still pretty good. I'd say the reward might be little less evident here. I think that with LPs one may forfeit some musical realism due to lower dynamic range available (higher noise floor). So the amp's potential sound appears to be program material quality dependant.

    The Crest remains a surprisingly well mannered PA amp, yes for a SR amp company, but no real surprise here when considering Crest previously indicated using computer matched pair of KEF 105 speakers in listening tests for products development. This is a good reference used in order to taylor their amps' sound.

    I'm pleased with the amp, it takes the program material you throw at it and reproduces such competently, which is basically what the job is. Btw when pushed somewhat (say 100 db spl peaks) the amp didn't get warm, although another amp was on top of it partially obstructing the radiators, it remained at room temperature. The compression feature did not activate and i didn't try to get it going, would be too loud level with boss at home...

    Installation gear is a little different world for amp connections, however it doesn't mean these come with poor sound, hell no.

    Richard
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  10. #475
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    I checked the grey twisted pair installation cable i used to connect signals to the Crest Audio amp and counted 10 wire twists per foot so shouldn't be a problem. Easy to identify on this type of cable, contrary to microphone type cables, since at every wire twist i can see and/or feel a small bump on the cable's jacket.

    Upon making these cable sets for the amp i did continuity tests on all and they were good. Even though they work fine i'm not really satisfied with the way i connected the drain wires used as circuit ground. Dumb me: two spade terminals on one input, and having their red plastic ring on, don't fit as nicely on the barrier strip screw for grounding, somewhat thick for the space, needing a little terminal bend.

    I can do better using terminals with no red plastic ring, as i have some, and install two of them thick behind the ground screw, but with their wire entry leg leaning a little to the left for one, and to the right for the other, these two making a slight "V" shape in the barrier strip. They'll fit more appropriately behind the single grounding screw for both channels. Will modify that connection when i get a chance. More later.

    Richard

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  11. #476
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    CREST AUDIO AMP INSIDE PICTURES

    As referred to previously, there ya go.

    The 30-day seller warranty/return privilege has expired. The 19 y.o. amp (2003) works well and sounds good so i kept it. I tested all three impedance settings (4, 8, 16 ohms) and they work fine. Turning off the amp, as recommended, before impedance switch changes to use different impedance speakers. I can also confirm it does have turn-on delay and turn-off muting, therefore no annoying noises heard during these steps, even with gain controls fully up, that's nice.

    Time was up to cut the seal on the amp and see what's in it, plus a possible explanation for the weight. What appears to justify the amp's heaviness is the pretty large toroidal transformer used vs amp size and the 75W RMS power rating. Transformer is about 7.5" diameter and 1.25" thick. The triangular bracket holding the transformer in place is an indirect proof that its heavy. Have not seen such on comparable amps in stock.

    Crest Audio has a reputation for overbuilt power supply. It seems to be true in the present case. Other similar size amps on-hand don't match these transformer dimensions, though the Mosfet amps for example have a little thicker one but a smaller diameter.

    The output devices are directly mounted on each heatsink, four devices per side (plus a temp sensor), coming from Toshiba Japan, and producing very little heat in my tests so effective convection cooling. That's a good thing since it is often said that heat is the enemy of electronic components. Other small size amps i own show more often having two output devices per side. As for the storage capacitors its written on them Nippon Chemi-Con so presumably Japanese too.

    Btw one has to be careful before purchasing this amp (or other Crest), since Peavey purchased Crest Audio in 1999 (late in year according to some). Crest business continued for a while but was eventually made part of Peavey. In my view this raises a question regarding amp quality, i.e. was a particular unit made by Crest or by Peavey? There's an unknown manufacturing switch date. For various reasons i'm confident that mine was made at the Crest factory in the USA.

    I have nothing in particular against Peavey, but i didn't want a Peavey amp, rather a Crest Audio one simply because i think Crest made better amps. Later Peavey integrated Crest Audio in their Commercial Audio division, therefore these became Peavey made amps. Plus the possibility that some be made in low-cost China for Peavey since this being the general trend in audio.

    There are some signs or clues when trying to differentiate a Crest made amp from a Peavey one, specially useful around the transition period between the two.

    Finally, Crest made amplifiers for others too: like Clair Brothers Audio; also in cooperation with Meyer Sound for systems used in Europe; even for Peavey, their ips 150 being similar to the Crest PA-150 i have. More later.

    Richard

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  12. #477
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    A USEFUL PIECE OF INFORMATION

    I've been using Caig's Deoxit Fader F5 for years in order to clean static noise on pots for example. This with more or less success, depending on gear, since static noise eventually comes back, sometimes sooner than later. I know other guys here also use Caig's F5.

    Recently i had it with noise coming back, so on my last visit to dealer i brought with me the Mackie mixer to have the first four channel gain pots (mic/line) replaced hoping to get some more years of silence. Long story short, the senior repair tech told me i'd hate to have to charge you $300-400. to replace these (labor, parts and taxes). I said i'll pay it this small mixer is just too useful to me as a "control center". He went to check in his computer and came back with bad news: all VLZ series mixer pots were discontinued...

    I told him i used Caig's F5 in the past but it hasn't been a lasting solution. These pots are sealed and the easy way to try to clean them is to remove the knobs and spray in the tiny cavity around the pot's shaft, hoping it will work. However, most interesting was the tech's comment about Fader F5: F5 is ok but we prefer to use Caig's F100. (these techs don't usually work on consumer gear, only Pro stuff, many being quite expensive units; they're not a cheap shop but at least they know their knee from their elbow, with mostly 20-30 years of service techs).

    He didn't explain their F100 preference but i might have found the reason. I had a quick look at Caig's F5 and F100 data sheets and in the formulation it says F5 has only 5% Deoxit while the F100 has 20% Deoxit, four times more. Probably better cleaning power, F5 might be too mild in some situations. I figure senior repair techs have tried a lot of things over the years and probably know what works better or less so.

    The tech offered me, free of charge, to spray a number of channel gain pots with Caig's F100, offer accepted, and using the same method as mine. Got home tried it, channel 1 static at 8-9 o'clock still there and channel 2 static around 12 o'clock remained there too, though the knobs were exercised. About a week later time to use mixer again, surprisingly no static noise on the pots sprayed!!

    Well, i doubt the pots have self-repaired themselves. I figure that after a while some F100 Deoxit found its way inside the pots these not being perfectly sealed? Its the only explanation i can think of. So far so good and it didn't cost me a dime. Next static noise issue i'll simply get a can of F100 like the pros use as this might increase my luck...

    Richard

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