Connect Tascam 388 mixer with Tascam 38, +other 38 related...

WhinyLittleRunt

WhinyLittleRunt

Member
I know it's been discussed before but I was thrown off about some of the talk regarding making sure you do not record in Repro mode while using the 388 mixer. I didn't think you recorded in Repro mode technically anyway? I want to get clarification on that either way and what the dangers are.

Otherwise, what do I need to use to get the two connected? I have an M308 mixer that I now realize has problems of its own and I don't think I'm interested in pursuing that as a project. It occurred to me that I could probably use the 388 as a standalone, which probably even works better than the 308 because it's an 8 bus mixer as opposed to a 4. I'm thinking since I already have a 1/4" to RCA snake I would just need a second RCA to RCA snake to accommodate connection from the PGM outs on the 388 to the inputs on the 38, correct? I'm also concerned about having to unplug and plug in stuff all the time during the process; if I can visualize the signal flow, I'm seeing MIC input on 388, set to Mic, choose a PGM odd or even (say channel 1 and 2) depending on the output/channel and with the outputs running from the PGM outs I should see signal on the 38, right? Then, if I want to playback, I would have to switch to LINE mode to hear the outputs of the 38... I think. Where normally I'd be in RMX mode to hear the built-in recorder. Aren't I able to leave Mic and line inputs connected on the 388 without it cancelling anything out or having to unplug stuff? I vaguely remember that I've had them both attached with no issue.

The second (technical) question I wanted to ask is if anyone who's worked on or rehabbed a 38 ever did a full recap of the unit and if it's worth it or not. I can see the voice cards being a necessity, but I might get OCD about it and feel like the whole thing needs a recap. I glanced at the power supply and that thing has a ton of huge caps (didn't check values yet) so that could get fairly expensive. Plus the rear connection board has a ton of caps on it also. The 38 is full of capacitors! Doing any of this would never reward me on my investment so I'd have to consider it a labor of... love? ...if I decide to do it...

Lastly, as I was playing with the 38 last night another thing that has always happened and I don't think it's supposed to: the reels don't stop fast after rewinding or FF. I'm assuming this is a reel table height adjustment or something like that? I've always gotten around it by just approximating where to stop the tape so I didn't overshoot it by so much but if it can be fixed or adjusted semi-easily I'm interested...
 
1. Yes you can use the 388 as a standalone mixer. The danger resides in the risk of a feedback loop. Using the 388 as a standalone is not ideal but can work. It's just not as risk-free as using something like the 308 where you have more source selection and monitoring flexibility than using the 388 mixer. Yes you can have sources simultaneously connected to the 388 MIC and LINE inputs on a given channel. If your live sources are all mics, then you can use the 388 LINE 1~8 inputs as your tape returns, but there is no way to monitor tape returns on any tracks connected to 388 channels that are monitoring MIC inputs, because there is no other way to access the LINE inputs other than that MIC/LINE/RMX switch...it's one source at a time...overdubs can be tricky, possibly requiring repatching to get it done. And back to the feedback loop risk...assuming the 38 outputs 1~8 are connected to 388 LINE inputs 1~8, you just have to be careful to make sure that for a 38 track that is armed and monitoring the input you don't accidentally have that corresponding input of the 388 switched to LINE and assigned to PGM 1. Like let's say you have MIC 4 assigned to track 1, you are monitoring the INPUT on the 38 to set the level and forget you had 388 channel 1 sourced to LINE and assigned to PGM BUSS 1. I know this might be a little hard to follow, but think it through with the 388 in front of you. The input being monitored for track 1 on the 38 will pass through to the output, which in my scenario is going to pass back to the PGM BUSS 1 output back to the 38 track 1 input and so on...*ssssqueeeeeeeee!!!!!*...opamp cooks...there are other possible scenarios too of course. You would just have to careful to watch your settings on the 38 and the 388. Again, it's not ideal because if no flexible input sourcing, hassles with overdubs, and risk of feedback loops. There might be a way to utilize the 388's L-R buss, monitor mixer and auto source/mute functionality to abate some of the issues to some degree, but it's still going to feel like a significant step down in functionality. I don't think I would ever choose to use the 388 mixer over a 308...the 388 mixer has impressive functionality as far as routing and monitoring, but you loose most of it when you aren't using it with the internal tape transport.

What's going on with your 308?

2. I always recommend if you are going to do a partial recap you ALWAYS start with the power supply. Are you having problems that indicate a recap is mandatory? I recap like an OCD madman but it has almost always been overkill...preventative maintenance. But sometimes it has been necessary and more often than not in this vintage of gear I've noticed improvements with the recap, but the biggest bang for the buck and for your time is the power supply...that feeds everything. Then from there I would recap only what is problematic, keeping in mind eventually a full recap will be necessary...it's inevitable eventually, which is often what is behind my efforts..."I'm going to have this [insert make/model here] for a long time...I've got it opened up anyway, I may as well recap it." Plus there's something disturbingly therapeutic for me about recapping, though I've had little time the past several years. HTH.

3. Sounds like you need to adjust the brakes.
 
Hey Cory, thanks for all that info... I knew if anyone was gonna have the answers, it'd be you for sure!

I'll start by saying I'll take your advice about avoiding using the 388 mixer due to all the complications it seems to introduce. I really don't want to damage anything in the 388 by accident either, since that unit (far as I can tell) works and records just fine. Last thing I want is another unexpected project. I may just want to use it temporarily to test record levels and the individual channels etc just to get an idea that things are at least working, albeit out of calibration...

The 308 mixer has two distorted channels and 2 distorted tape returns (the tape returns could honestly be the entire buss of 3 and 4, since they share 3/7 4/8 and they are both damaged). I know I pulled it apart last year and changed some parts on one of the busses, in fact I think I even changed the op amps... if you think it's a worthy mixer to keep around and worth the time to repair it then I will, it only takes one experienced fellow to steer me in the right direction when I'm down and out about my gear lol! What basically happens on regular channels 7 and 8 is the VU pegs instantly and the sound is very distorted and squelchy. Same on the tape returns. I'm guessing somehow they are all linked in the circuit since it seems highly coincidental that the corresponding channels/returns both have the same problem... in fact, I just came to that realization seconds ago. Maybe you have more input on this... have you owned a 308 before? It's what seems like a nice mixing board, and it's heavy and huge so getting rid of it would be challenging, and getting something different is just cost-prohibitive right now, but I'm curious to know what you think...

Also, I get a Zen out of recapping too. I have the right tools so doing it isn't challenging. I have definitely seen improvements in the gear I've worked on. Right now, there isn't specifically anything that makes me think a recap is necessary, I just figured if I want it 100% my OCD isn't going to let that be unless it's recapped... I'm sure you know the feeling.

I looked briefly at the manual late last night about the brake adjustment; I will see what I can do to remedy that. It's not terrible but it definitely takes longer to stop the faster it's going.

EDIT: Well, I made a slight liar out of myself... Ok, I went down and did a quick test to see exactly where the issues are on the 308. So, the channels themselves are fine. 1-8, everything works and sounds right monitored from L/R (I'm running an audio tone generator off my phone for a consistent sound and checking the channels that way). It's when I assign them to the busses I have a problem with 3/7 and 4/8. Bus 3 VU meter doesn't work until I raise the fader to maximum and it's very touchy. Bus 7 when turned on is distorted and squelching. Same with 8. 4 seems to be ok, even though it is linked to 8. So the problem lies in the bus section somewhere, that much I can tell.
 
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I've had a clapped-out M-308, and I currently have a clapped-out M-312 with a poorly-executed balanced line input mod. The M-312 has therefore been a great source for swapping parts to mintify a 388 I refurbished and sold, and an M-106 console I have up for sale...and I'm going to be swapping the pan pots with those on my prototype 12x8 Tascam console because the M-300 pots have center decent. My choice to cannibalize the M-312 is no indication of my affinity to them. If a vintage budget-conscious 4-buss console is on the procurement short-list the M-300 would be on it, especially the M-312 because of its more fully-featured master section, but in any case the M-300s in general are a great non-modular console...the are outfitted with what was the cutting-edge opamp of the day (and is *still* respected decades later), and are a great example of thoughtful engineering in their construction and feature-set resulting in something you just shouldn't have been able to get at that price point. And they aren't all cramped on the control surface. I don't want to take the time to tout the feature-set...would be much easier to describe in-person or on a video...but you're going to have a hard time finding something that matches up at all points for what you can find them for. I think they sound really nice. And though I see some pretty stupid prices for them recently, they can still be found for a really good bargain. Again, if I was looking for a non-modular 4-buss mixer the M-300 series would be on the short-short list. If yours hasn't been molested or suffered trauma I'd try and sort out what is going on with it.

And yes the 388 is a good interim stop-gap solution to get you by, but I think long-term you would be frustrated with loss in functionality and kludgey work-arounds you would have to employ.

So let's help me get a firm understanding of what is going on...where can you hear the squealing/distorted audio?

* At the buss out jacks?
* What about if you assign the affected busses to the main buss? Can you hear the bad stuff at the main buss outs then too and in the monitor buss (like headphones if you monitor the main buss)?
* You mentioned the tape returns are affected...which ones? Where do you hear the bad stuff? Through the input strips if you are monitoring the affected tape returns? How about through the AUX buss(es) when monitoring the affected tape returns inline...? You hear bad stuff in the AUX buss(es) then too?

Be as concise and specific as you can...it could help us narrow down where the problem(s) reside.

Has this console suffered any known trauma or is there any visible physical damage to the chassis?
 
I think I need to understand more thoroughly how a 4 buss mixer would interact properly with an 8 track recorder, even though it says it has 8 tape returns, 2 share a single buss with their own off/on switch etc... that's part of the problem, is when I had it hooked up back in the day, I thought I had it routed correctly but I'm sure I didn't. Either way, I definitely still have a problem, but I investigated it a bit closer.

The way I have my sound test set up is using an audio signal generator app to the line input on channel 1. From there, I can assign it to pgm busses 1-4. On its own, the signal to line input and directly sent to L/R output is fine. The signal when sent to the PGM busses is fine for 1 and 2. 3 and 4 are not only distorted at even the lowest level, they actually sound like a pulse-width modulation effect you'd get on a synthesizer if I sweep the fader. I tried listening to the signal off the monitor outputs, same thing. When I say "tape returns" what I really mean, for testing purposes, is that I'm plugging my signal directly into 1 of the 8 tape returns (in this case 3/7 or 4/8 for testing the bad strips) and hitting the tape button on the strip, which disables the fader but uses the level pot instead. Same distorted sound. I can't figure out how to patch and monitor auxiliary because I'm shot... lol

What it sounds like though, to me, is something in the main output circuit rather than the 2 busses themselves. That's my half-cocked assumption now that I tested directly off the pgm outputs and saw no issue...

While I patiently wait for your extremely helpful and thoroughly appreciated response(s), it's user manual time....

Oh, and regarding condition, the mixer was in pretty much pristine condition when I got it. Doesn't have any dents or dings etc. It looks shabbier from sitting in my basement 9 years! Also I don't recall it having this issue when I first got it so this is another thing that leads me down the re-cap road after it's been sitting dormant for so long.
 
I don't come here often and you guys ^ know what you are about but I would like to make a comment about 'Re Capping' in general.

There seem to be a bit of mania for the task? Anything over 10 years old..MUST change those electros!! Ain't necessarily so, not even at 20+yrs old.

The very first task is to check the audio performance against specification. Is the LF response on specc' into the rated load? If so that channel at least is fine. Would be much better to check the LF THD but that is probably asking a bit much? The nitty-gritty here is, if you don't have the gear to do a response check (or the smarts) FFS don't mess with the 'tronics!

Power supplies are a bit different. These often run quite warm, even hot and that reduces cap' life drastically (halves every 10C rise) If the capacitors are going to be replaced it is wise to use 105C types if they will fit. Probably will since e'cap technology has advanced hugely in two decades.

DO NOT be tempted to increase the value of the PSU capacitors! From 2200mfd say to 47000 EVEN if you can get them in. You will give the transformer a harder time and the resultant improvement in line ripple will amount to but a few dBs.

As you were.

Dave.
 
Yeah I hope I'm doing my due diligence steering people away from automatically jumping at wholesale recapping. Most of mine is with the idea I'm going to keep the unit for a long time and getting it done as a preventative maintenance task...and I agree on the power supply...it's more critical.

I have measured LOTS of original caps that have come out of 30-35 year old Tascam gear and I have yet to find *one* that was out-of-spec as far as the capacitance. I don't have an ESR meter so I don't know about that, but they were still in-spec as to their capacitance.

And it is wise to consider every time you pull something apart and put an iron to it you are introducing risk...potentially bringing on new problems.

Electrolytic caps *will* fail eventually, but some brands are better than others, some designs are better than others...not all are created equal so be mindful of your skills, the goals, and whether or not it is reasonably assured caps are really the problem.
 
Isn't it a general rule to only fix what's broken?
:D :D :D

As to Cory's statement about old tascam gear still having the caps be in spec, I'll add this.

In guitars there is a huge demand for old 50s bumblebee caps, as used on vintage Les Pauls. People pull em out of old Hammond gear and resell just the caps for a premium.

It's amazing how many of these are still in spec. Now keep in mind these are paper in oil and not electrolytic, but still. Quite remarkable.
 
Yeah the old 2,000uF 80V primary filter caps in any of the Ampex AG-440/MM-1000 electronics module power supplies I've ever pulled still measures in spec as to its capacitance...and all of those supplies I've had are from the late 60s. Again, I never measured the ESR, but when rebuilding them I always replace those caps anyway, because the 2,800uF Mallory computer grade replacement has much lower ESR spec than the original part. But I think the original part would be fine. Now, any of the orange paper can Beaver caps? They sucked from the beginning. I always pull them.
 
"If it ain't broke....."
Yes, a good general rule. There are exceptions. Some things have a limited and predictably life. Aircraft parts e.g. but these are components that are KNOWN to fail, usually by fatigue, after a certain service period because on the ground tests are done. The metals are of a very carefully controlled composition and the heat treatment etc has to be done to rigid specifications.
There are safety critical bolts, clips and other parts on cars that must not be re used but again, controlled and tightly specified parts the lifetime of which has been predicted.

One foil cap that has a certain 'cache' in the guitar industry is the Mullard 'mustard' . I personally do not believe they sound ANY better (or worse!) than any other but I CAN say that in my 70 years I cannot recall one ever failing, short or even leaky!" And they were very common in Philips radios and TVs.

Dave.
 
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