How much does a circuit matter????

[soundguy]

periodically we have to wax about mackies, dont we?

I dont think mackie's sound BAD, there are certianly designs that are just ruthlessly impossible to work with and mackie certainly isnt leading the pack. they just dont sound good, and if you are putting stuff like class A neve or api into them, mackie will always be the lowest common demonic-ator that your mixes will boil down to. I couldnt hear things happening with my ghost, and a ghost sounds about a billion times clearer in the mids than a mackie, so go figure whats happening to transients on a mackie.

ANYWAY, re-reading my post, my comments on tube gear are pretty un-fair. I dont really use tube gear after a mic because I have a very particular form of mental retardation. I always have a really hard time getting tube tracks to sit with transistor tracks. I dont know what my problem is, but its a definite problem. I always think of tube amps as mush machines, but the only tube stuff Im using is stuff designed in the 50's/60's, I most certainly can not comment on any new tube designs as I plain and simply havent used it. All I know is that Ive never gotten excited about a tube mic pre the way Ive gotten excited about a 1073, but thats largely personal preference.

dave

 

[Flatpicker]

[quote author="bluebird"]I have a Lynx II card.[/quote]Whoa! Well... no problem there! (I wish I had one of those!)

 

[Flatpicker]

[quote author="Marik"]I just went for a three weeks trip. When got back, I realized that forgot to turn off my probably 20 years old D75. Still works...
[/quote]Probably needs a cap job by now. I've got a Harmon Kardon 730 receiver that needs a cap job, but I'm debating whether or not it's worth the trouble when you can buy slightly used Haflers for ~$125.

 

[AP]

i plugged my old gibson ES330 into the mackie, then the hamptone.... the mackie made the guitar sound dull, flat, and it honestly sounded like it was out of tune... i don't know how. then i plugged it into the hamptone and it sounded phucking amazing. smooth, warm, dynamic, etc. the wierd tuning thing may just be what how the mackie squishes harmonics.

I think it wise to consider what you are testing here....

Typically, guitar pickups like a really high input impedance - certainly over 100k... 1M would be very fine...

The Hamptone (IIRC) is a Fet input preamp - depending upon how it is setup, it is likely to present a really nice high input impedence.

The Mackie, I would guess you plugged it into a line input. Without knowing specifically, I would guess this is probably 10k or so input impedence - way, way too low for a guitar. That alone would kill the sound.

I would also guess that the Hamptone might add a fair bit of harmonic-distortion-you-like. The Mackie would by comparison, be rather clean. So, perhaps it is not so much how the Mackie squashes harmonics, but how the Hamptone adds them.

(Although this latter issue would be academic, compared with the effect of the impedence mis-match).

Jus' guessing...

Alan

 

[NewYorkDave]

I like the small Mackie mixers for applications where reliability and ease-of-use take precedence over absolute sound quality. I've chosen them for editing suites, TV trucks, small lecture-hall PA systems and the like. I've used a 1402 to mix my own demos, and found it inoffensive enough if I kept my levels under control. But for music recording, there are better (albeit mostly costlier) options.

RE: Phase Linear--In the repair biz, we used to half-jokingly call them "Flame Linear" because they had a problem with the thermal coupling in the output stage that would sometimes cause them to burn up. I never thought they sounded very good even when working properly.

The Crown D75 and especially the D75A are fine amps for a nearfield monitoring system using relatively efficient speakers. They're the de facto choice in broadcast because of their reliability--and they're easily repaired if something does happen to go wrong. Ian, I'd go with that one since you own one already.

I despise NS10s driven by ANY amp. I mixed an album on them 11 years ago and I would never, ever do that again. But then again, this is just the opinion of an unknown who has no gold records to his credit.

 

[Learner]

[quote author="NewYorkDave"]

I despise NS10s driven by ANY amp. [/quote]

:grin: they are the ALL time CLASSIC consumer "pro studio" monitor for most muso/post audio engineers, that's why they have some sort of "status" or "cult" following?........the price they are going for is no difference to hi fi audiopoo fanatic accessories.......

might be better off picking up some cheap vintage hi fi Altec or some Japanese retro monitor systems with proper crossover filters inside the package :shock:

Nevertheless, it is always essential to have a pair of those prosumer hi fi speakers to compare your mix. :green:

 

[soundguy]

I have questeds in my studio, which I think totally rule the land, the only problem is, they arent very popular in america and as such, most people dont know what the hell they sound like, so Im always faced with a seasoned musician wanting to hear what a mix sounds like on NS-10s. I should get a pair, simply because people know what they sound like.

dave

 

[owel]

I read tracks mixed with an NS-10 monitor tend to sound boomy, bassy, when played back on a normal system. .. somehow, during the mix process the lack of bass of the monitor is overcompensated.

And tracks mixed with big subwoofers monitor sound thin and lacking bass when played back on normal systems. Not enough bass.

Of course, your mileage may vary depending on how good the mastering engineer is and how well he *knows* his particular monitor.

 

[soundguy]

[quote author="owel"]I read tracks mixed with an NS-10 monitor tend to sound boomy, bassy, when played back on a normal system. .. somehow, during the mix process the lack of bass of the monitor is overcompensated.

And tracks mixed with big subwoofers monitor sound thin and lacking bass when played back on normal systems. Not enough bass.[/quote]

this is lesson one when learning to mix...

If you have bas tracks that are loud on ns-10's, you know youve gotta bring the bass back ALOT. Thats one of the only reasons I ever check on nearfields, just to check the imaging at the bottom- there should be none.

dave

 

[thermionic]

If your Phase Linear amp is one descended from the Hitachi lateral mosfets apps data that Pink Floyd used on tour throughout the early '70s, there is a whole industry offering improvements you can add to it.

I had a Hitachi-based amp that sounded awful, and noticed the sound quality was totally dictated by the psu - it only sounded any good with masses of expensive ELMA 'lytics. I upgraded the PSRR with the addition of constant current sources, fitted a massive poly cap at the front (it only has 1 cap in the path) and paralleled masses of caps in the unregulated psu; it now sounds fantastic, no lie, you wouldn't recognise it sonically from the original raw design.

If you get a schem for the PL and see it is of Hitachi descent I can show you some cost-effective upgrades (<$30/$40 all in), you won't believe the difference.

Personally I think Mackie can be unfairly maligned; they're not musical like a discrete path, but they redefined the price-point when they came along in the early/mid '90s IMHO, and you can get results if you have outboard. If Zep or Spector had mixed their songs on Mackies there is no way they would sound as vibrant, but that doesn?t make Mackie **** - it?s an ic-design with no transformers, what?s it supposed to sound like?

AP is bang-on with the impedance remark, no 10K or 20 K i/p will sound right if you plug a mega high-Z pickup straight into it.

Cheers,
Justin

 

[thermionic]

Hey Ian,

I've pm-ed a link to you for a site with PL schems. I will say that in hindsight, I reckon your amp could well be a completely different design to the 7000 / Hitachi topology. I know the 7000 was based around it, as it was a high-power design and lateral fets were very modern for the early '70s, but the other amps in the PL range could well be completely different.

if you really want to take it to extremes, take a mackie (anything smaller than the 8 bus) into a mastering room with $15,000 speakers. play some incredible-sounding raw (uncompressed) 24 bit material through the mackie as one sidechain, and through any other mid to high end mic pre on the market.

I've used an 8-buss next to expensive class a channels. Of course, the Wackie sounded far inferior, but then you have to consider that its cicruitry is somewhere around 1/50th of the price of your average discrete channel...

Until Mackie came along the "project" mixer market was dominated by noisy, unreliable consoles, I respect what they have achieved (at the price-point of course).

Justin

 

[AP]

I have a hand-draw schematic of the PL400 of that vintage - uses BJTs throughout. I know the schematic is correct (for the version of amp that it came from) as I drew it myself, and used it to repair lots of those things (not madly reliable on the road - one of the biggest problems was the thin aluminium chassis 'tearing' under the weight of the transformer, when the amp racks were dropped off the back of trucks....)

I am not at all sure my schematic will scan at all well - it is drawn in pencil (faded from much use) on graph-paper. I will give it a try if you are really desparate (ie. need to fix it).

... but in terms of 'improving' it - I really wouldn't bother - you would need to redesign it to improve it (it is a really rather standard class-B arrangement 'of the time').

I am always a bit suspicious of suggestion that you can turn sow's ears into silk purses simply by replacing caps, or using oxygen-free output terminals.... (Although I did read that turds actually *can* be polished if you use the correct stuff - I think that snake-oil was the suggestion...)

... put the thing on ebay, and buy a decent hi-fi amp (no - NOT one with glowing bottles in it, and 10% THD - a proper 'modern' one).

Also, Crowns if that vintage were always more highly regarded than PLs... so use that.

Alan (hard-hat on!)

 

[PRR]

> If your Phase Linear amp is one descended from the Hitachi lateral mosfets apps data

I don't know if they used the same chassis on the MOSFET amps as on the originals. I know the picture above looks *just* like my original recipe PL400 except a nicer faceplate. Same bent sheetmetal heatsinks and offset iron. They had FTC trouble with those heatsinks, so I would think they revised it soon after. But maybe the bent-tin sinks were essential to the price-point.

If it is the original: it was revolutionary in its day. Sorta like the Model T. (Or maybe the first Hemi-Cudas.) You got a LOT of watts for your dollars. It beat the unbeatable goal of "$1/Watt" (remember a dollar was worth something those days: pack of cigarettes with change, or 3 gallons of gasoline). It spawned an industry of high-power amplifiers at affordable prices. It didn't have any of the distortions we knew so well from tubes. It wasn't like some of the early transistor amps. It took some time for us to clear our ears and realize that it had its own flaws. You would not like to drive a Model T today. A Hemi-Cuda is still a blast, but very crude and un-handy for everyday driving compared to a recent Subatoyonda sedan.

> 'improving' it - I really wouldn't bother - you would need to redesign it

Agreed. I would even say it was ahead of the state of the art. Few consumer amps had that much LF open-loop gain or swung so close to the rails. But they were pushing 1970 transistors to the edge of feedback stability. You really can't get great audio performance that way with 1MHz-3MHz devices.

Given an old one: probably all the electrolytics are due for replacement. It might make an audible difference. A little more main power capacitance wouldn't hurt, though you should probably use an oversized rectifier too. (It took a while to learn about peak currents in silicon rectifiers with large filter caps.) If you want to, replace the input cap (the only signal cap) with gilded-sow-ear: it may make a difference (though the old film caps were often very good). Pots, jacks, power cord, rubber feet as needed. You'd still be on the bleeding edge of 1970, which was not one of audio's finer times, especially in super-powered amplifiers.

To do much more (i.e., to make it modern and near-transparent) pretty much comes down to ripping all the small bits and output devices out and starting over. *Maybe* a talented designer could replace the outputs and other bottlenecks and do something better on the same PCB. In the time it would take to think, build, and test, you could go work at McDonalds and earn the money to buy something modern. A new Crown bargain-line XLS 202 amp makes the same power as the legendary DC-300A for $269. The Yamaha P2500S sells for the same price as the PL400 did ($399) but makes more power and is reputed to sound very good. Used dinged amps sell for less (though not a lot less: disco operators will buy any high-power amp that works, setting a bottom on the market).

Don't overlook 1980s Japanese home hi-fi. They made a lot of trash (OK, a lot of stuff priced to sell), but there were some very good amps too. I have a Yamaha that was clearly aimed at the high-end of the time: powerful, VERY heavy, chassis all dented with stiffening hexes and copper-plated, subtle tone controls that can be bypassed. I bet you could pick up a 1980s top-line Sony or Yammerer or Kenwood with a dented corner for $100, or free if you know the right person. Sometimes these beauties languish in garages because someone got seduced by a newer-lower-longer-sexier model, and never bothered to trade-in or sell the old mistress.

 

[thermionic]

If you?re curious PRR, I can email you the schem for the ?Hitachi-based? amp I use (related to the PL 700B, not 400). Although it retains the basic topology suggested by Hitachi (inventors of the lateral mosfet, for anyone not aware) it also contains one or two neat additions such as the constant current source that stops voltage fluctuation affecting the quiescent bias to the ?current mirror? transistor pair in the driver stage.

Just a suggestion: Ian - check what your amp is worth on ebay, and compare what it?ll fetch against what you?ll pay for heatsinks and a large mains transformer of similar size. If it doesn?t fetch much more than the value of the surplus my advice would be to build a new topology into the case. In my experience (I work partly in the hi-fi market (for my sins?) and hear grillion pound amps regularly) power-amps constitute an area that is absolutely prime for diy. With the exception of the Chinese-made NAD amps I?ve seen of late (they really offer a hell of a lot for the cash) I genuinely reckon you can kick the hell out of most commercially available ?audiophile? designs in terms of cost-to-performance ratio. A suggestion would be to make a board along the lines of a topology you fancy, say a Pass design, and build it into the PL casework.

Power-amps really are an area where you get what you pay for IMHO, I?ve yet to see a financial shortcut to nirvana. Class A costs particularly, and if you go for surplus parts you can make a class A monster for less than a fraction of what you?d pay for a commercial design.

Cheers,
Justin

 

[PRR]

> check what your amp is worth on ebay

Asking $275 Buy-Now, bidding $1.50 with 4 days left:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=23787&item=3740748433&rd=1&ssPageName=WDVW

 

[bluebird]

Sweet I could get some cash for it...

Heres an update on my monitoring chain....

I'm using my roomates home stereo speakers. they are very nice. I think they are KEF Q something.... 6 ohms. two 6 inch woofers with the tweter in the middle of one, tannoy style.

I have my sound card going directly into the Crown 75A.

OK so I can hear SOOOO much more now. The quick mix I did of a song sounded better that ever. I would like the crown to have a little more. it only sounds better than the PL 400 at low volumes.

All and all I've learned alot from this whole thing. Once again the Group DIY came through for me!!!! :thumb: