Tascam TM-180 as mod platform?

[svyet]

Stumbled on these mics not long ago out of interest in the 18mm aluminum-diaphragm TM-80. These TM-180's (34mm gold) are also very cheap and use through-hole components and a transformer. One vendor with a couple used ones for sale was kind enough to take them apart and send me pics of the boards with permission to post here for you guys to look at and determine what kind of circuit it might be - and therefore what kind of mods might be useful or desirable for anyone looking for a platform (and one that includes two switches that could probably be configured for things like pickup pattern if you didn't want to keep both pad and low cut). At the very least, they make for a very handsome and modern donor body that comes with a hard case, sleeve, and shock mount for around $70 plus tax new. Thoughts?

 

[k brown]

You sure the capsule is aluminum?; never seen one made like that.

 

[svyet]

You sure the capsule is aluminum?; never seen one made like that.

TM-80 has an 18mm aluminum diaphragm. It's been mentioned HERE before in a conversation about moisture-resistant capsules. It was reading about the TM-80 that I discovered the TM-180.

The TM-180 (of which this thread is about) has traditional 34mm gold-coated diaphragm

 

[k brown]

TM-80 has an 18mm aluminum diaphragm. It's been mentioned HERE before in a conversation about moisture-resistant capsules. It was reading about the TM-80 that I discovered the TM-180.

The TM-180 (of which this thread is about) has traditional 34mm gold-coated diaphragm

My fault - I read your post too fast . . .

 

[svyet]

In your defense, it probably would have helped if I had differentiated them in the original post!

 

[Voyager10]

From the pictures the circuit looks most similar to the much copied ADK A-51/MXL 2001/V67 design (example at https://groupdiy.com/threads/mxl.84887/).

Not an exact copy if that transistor is an (NPN) 2SC1740, rather than the more usual PNP 2SA1015.

As a mod platform a lot depends on the mechanical properties - if the body/headbasket is solid it's worth thinking about capsule upgrades (definitely) and circuit upgrades (maybe). If it has annoying resonances that's all you'll be hearing whatever else you change.

 

[Icantthinkofaname]

From the pictures the circuit looks most similar to the much copied ADK A-51/MXL 2001/V67 design (example at https://groupdiy.com/threads/mxl.84887/).

Not an exact copy if that transistor is an (NPN) 2SC1740, rather than the more usual PNP 2SA1015.

As a mod platform a lot depends on the mechanical properties - if the body/headbasket is solid it's worth thinking about capsule upgrades (definitely) and circuit upgrades (maybe). If it has annoying resonances that's all you'll be hearing whatever else you change.

I'd recommend an iSK BM-600 for a donor mic/mod project. But that's because it's fairly U87 shaped and has 3 patterns.

 

[Khron]

I'd recommend an iSK BM-600 for a donor mic/mod project. But that's because it's fairly U87 shaped and has 3 patterns.

That, and apart from the PNP follower and low-ratio transformer, everything else is a pretty accurate copy of the U87Ai circuitry. It's also branded as the Devine BM800 btw.

 

[svyet]

Thanks for the suggestions all!

From the pictures the circuit looks most similar to the much copied ADK A-51/MXL 2001/V67 design (example at https://groupdiy.com/threads/mxl.84887/).

Not an exact copy if that transistor is an (NPN) 2SC1740, rather than the more usual PNP 2SA1015.

As a mod platform a lot depends on the mechanical properties - if the body/headbasket is solid it's worth thinking about capsule upgrades (definitely) and circuit upgrades (maybe). If it has annoying resonances that's all you'll be hearing whatever else you change.

For what it's worth, the seller was kind enough to send me pics of the boards from another TM-180 he had for sale (see first two pics below). I'm just now noticing how different some of the components look (color, labeling, etc.). Might be easier for you to decipher the circuit since more of the components have labels, and some labeling on the board is visible, e.g. below the transistor has "A1015" printed on the board Any fundamental differences here? Does anything look modified or simply difference in component brands based on availability? Noticing the labeling on the transformer is gone, but the screws look untampered with at first glance.

Also worth noting that the older Tascam LD-74 was manufactured by MXL (see third pic), so at least in the past I guess it wouldn't have been a copy of MXL, but the "real deal" haha, though apparently the LD-74 is an MCA SP-1 copy with a Schoeps circuit in it according to Recording Hacks. All of that to say, a lot of cross-pollination going on.

I'd recommend an iSK BM-600 for a donor mic/mod project. But that's because it's fairly U87 shaped and has 3 patterns.

With the pattern circuitry already built in, that sounds like an easy and immediate way to take full advantage of a new capsule. Thanks for the heads up!

That, and apart from the PNP follower and low-ratio transformer, everything else is a pretty accurate copy of the U87Ai circuitry. It's also branded as the Devine BM800 btw.

Would you change those two things or anything at all on the iSK/Devine, or would a good capsule be "good enough" by your estimation?

 

[Voyager10]

Interesting - the components around the 'C1740' transistor are typical of the U87 EQ circuit, which is normally a feedback network around the FET. I'm assuming the FET's on the top PCB (with the switches), so this is something different.

Possibly they've added an extra stage in the signal path to do 'U87 EQ'? This would need to be bypassed if you put a 'flat' capsule in it.

 

[svyet]

Interesting - the components around the 'C1740' transistor are typical of the U87 EQ circuit, which is normally a feedback network around the FET. I'm assuming the FET's on the top PCB (with the switches), so this is something different.

Possibly they've added an extra stage in the signal path to do 'U87 EQ'? This would need to be bypassed if you put a 'flat' capsule in it.

For what it's worth, there is indeed more circuitry on the disk on top. See first two pics. Based on your descriptions, there are already too many unknowns for me personally to spend any money for discovery, but maybe someone else is curious enough. It's definitely a very handsome mic with a more modern look, and therefore a great candidate if my intent was to change everything (e.g. Schoeps/KM + Flat 47). Perhaps later on!

There is the TM-280 as well that immediately struck me as a good body for a Sony clone for anyone working on something like that. See third pic.

 

[Khron]

Would you change those two things or anything at all on the iSK/Devine, or would a good capsule be "good enough" by your estimation?

Depends what exactly it is that you're after..?

 

[Icantthinkofaname]

Thanks for the suggestions all!


For what it's worth, the seller was kind enough to send me pics of the boards from another TM-180 he had for sale (see first two pics below). I'm just now noticing how different some of the components look (color, labeling, etc.). Might be easier for you to decipher the circuit since more of the components have labels, and some labeling on the board is visible, e.g. below the transistor has "A1015" printed on the board Any fundamental differences here? Does anything look modified or simply difference in component brands based on availability? Noticing the labeling on the transformer is gone, but the screws look untampered with at first glance.

Also worth noting that the older Tascam LD-74 was manufactured by MXL (see third pic), so at least in the past I guess it wouldn't have been a copy of MXL, but the "real deal" haha, though apparently the LD-74 is an MCA SP-1 copy with a Schoeps circuit in it according to Recording Hacks. All of that to say, a lot of cross-pollination going on.


With the pattern circuitry already built in, that sounds like an easy and immediate way to take full advantage of a new capsule. Thanks for the heads up!


Would you change those two things or anything at all on the iSK/Devine, or would a good capsule be "good enough" by your estimation?

You should only need to change a capacitor or two if all you want is extra high end roll-off.

If you're gonna spend $150+ on a good capsule you might as well build a clone from scratch.

 

[MicMaven]

I'd recommend an iSK BM-600 for a donor mic/mod project.

Hmmm.... from my research, that one is nearly unobtanium in the US. Aussie vendors on eBay sell them for more than $100 plus $45 US to ship them to the US. Kinda expensive for a donor body, I think.

As for the TM-80, B&H Photo Video dot com frequently sells that model for $39. I acquired a new one in December for just $29 (including shipping). The original post included a photo of the Tascam LD-74, which I also acquired used in December. I plan to use both as donor bodies.

I can provide photos and measurements of both models if that interests anyone comparing different bodies, components, etc.. Just ask. / James

 

[svyet]

Depends what exactly it is that you're after..?

Still figuring that out

You should only need to change a capacitor or two if all you want is extra high end roll-off.

If you're gonna spend $150+ on a good capsule you might as well build a clone from scratch.

That thought comes to me quite often. I'm just continuing to throw things at the wall and seeing what sticks, as well as figuring out actual needs too. Not looking to build something for the mere sake of it.

Hmmm.... from my research, that one is nearly unobtanium in the US. Aussie vendors on eBay sell them for more than $100 plus $45 US to ship them to the US. Kinda expensive for a donor body, I think.

As for the TM-80, B&H Photo Video dot com frequently sells that model for $39. I acquired a new one in December for just $29 (including shipping). The original post included a photo of the Tascam LD-74, which I also acquired used in December. I plan to use both as donor bodies.

I can provide photos and measurements of both models if that interests anyone comparing different bodies, components, etc.. Just ask. / James

Pics would be great! I've seen some pictures on Recording Hacks of insides, but why not post some more detailed ones here. Personally, I like the small size and shape and simplicity of the 80. And at its price, it sure makes for a great donor body.

 

[MicMaven]

Pics would be great!

Roger. I am working on it. (I am distracted today working on a course guide for a handicapped ham radio camp I help teach ... please stay tuned.) James

 

[svyet]

Roger. I am working on it. (I am distracted today working on a course guide for a handicapped ham radio camp I help teach ... please stay tuned.) James

A noble and worthy "distraction" at that! No rush!

 

[MicMaven]

Pics would be great!

Good Day - I finally got some time in my ersatz home (photo) studio - so I attach photos of the Tascam TM-80 - and you guys may ask for more specific close up images if that would help - just ask. The PDF is a chart listing various measurements of the TM-80 and LD-74 microphone parts. Hope this helps some. James / K8JHR

 

[MicMaven]

Good Day - I finally got some time in my ersatz home (photo) studio ...

Howdy y'all. Here are photos of the Tascam LD-44 (made by MXL) with chart of dimensions as per above TM-80. Let me know if you need additional images or measurements and I will do me best to accommodate same. This time, I attach the measurement chart as a photo image. Cheers!

James /K8JHR

 

[svyet]

Wow, super thoughtful..thank you! Excellent pictures. And the spec list! The LD-74 definitely is a readymade DIY platform, whereas the TM-80 would require a lot of finessing (i.e. fabrication..). But not a bad mic as is?