Monoprice LTM500 Tube Mic
« on: September 16, 2020, 04:48:14 PM »
Monoprice appears to have just released a multipattern LDC tube mic at $200
https://www.monoprice.com/product?p_id=625879

Along with solid state multipatern and cardioid only mics

Anybody cracked one open yet? Curious about the circuit and build quality as compared to other chinese tube mics. Not a bad retail price, I imagine the'll be cheaper street price down the road. Here's hoping it's mod-friendly, or even just a decent mic as-is.


Re: Monoprice LTM500 Tube Mic
« Reply #1 on: September 25, 2020, 11:40:56 AM »
Monoprice appears to have just released a multipattern LDC tube mic at $200
https://www.monoprice.com/product?p_id=625879

Along with solid state multipatern and cardioid only mics

Anybody cracked one open yet? Curious about the circuit and build quality as compared to other chinese tube mics. Not a bad retail price, I imagine the'll be cheaper street price down the road. Here's hoping it's mod-friendly, or even just a decent mic as-is.
Looks like the Alctron and Nady tube mics. Expect a K67 capsule, flat circuit, and it'll probably have the same filtering caps as well. I'd be cautious as some of the Chinese tube mics are soldered in place rather than socketed but also a pain to access.

I'd just buy an Apex 460 or the Alctron U47 looking one since I thinking those have tube sockets.

If the frequency response is accurate (which I doubt on a super cheap Chinese mic) it could be interesting. Pretty flat, then +2 dB at 5K, then what looks like +5 at 10K. That pretty much confirms it's a Chinese K67, just not the worst around. I would expect it to be a bit sibilant if you don't mod it. Not harsh, but a bit airy like the Behringer B2 Pro or CAD M179.
« Last Edit: September 25, 2020, 11:52:18 AM by Icantthinkofaname »

Re: Monoprice LTM500 Tube Mic
« Reply #2 on: September 30, 2020, 11:48:59 AM »
I have a handful of the Alctron/Nady/Apex/etc. mics and have modded them, including some with the soldered in place tube (FYI K&K Audio sell some individual pin sockets which make it possible, with care, to convert to socketed).

Monoprice is local and I use their A/V gear a lot for work and am generally very happy with their quality/price ratio. I'm hopeful that extends to these mics, and that they are in fact mod-able.

Re: Monoprice LTM500 Tube Mic
« Reply #3 on: November 18, 2020, 08:29:43 PM »
They are down to $150 so I ordered one today to use for donor body in M49 build using the Oliver Archut alternate design at http://www.tab-funkenwerk.org/ami-parts/mic-kits/m49a-kits/m49-schematic/.  I'll let you all know how it goes.

Re: Monoprice LTM500 Tube Mic
« Reply #4 on: November 21, 2020, 01:39:55 PM »
The kit is nice, except the microphone is a bit small, limiting transformer choices. It is a bit like a longer BM800, no more than 45mm diameter. The PCB seems well-designed, with 6 WIMA film caps, socket for 12AX7 tube, etc. I have not traced the circuit yet, since the plan is to gut it.

Re: Monoprice LTM500 Tube Mic
« Reply #5 on: November 21, 2020, 01:42:51 PM »
Width

Re: Monoprice LTM500 Tube Mic
« Reply #6 on: December 06, 2020, 11:20:18 AM »
Peter J left this fine review on Monoprice's website, which is so helpful. Apparently it's the Apex 460/HST11A circuit with a 17:1 transformer (he mentions this in his review for the LC-200 Fet mic, which I'll include here as well. I ordered the LC-200 and it seems like a decent enough mic in a nice little package. Body seems a bit less robust than other mics, but I'm sure it would perform just fine. Haven't put it through it's paces yet.

LTM-500 review by Peter J:
"
A smart looking stubby HT-11a
They shrank the C12-inspired 460 mic...the width is the same (with a slight taper to the base) but the overall length is only about 19cm vs 25cm for the 460 family. The circuit has been slightly upgraded with a surprising genuine polystyrene 1000pf input cap, some Wima box caps, and a nifty extra board with a cutout that wraps around the socketed 12AX7. The output coupling cap is still a 1uF 400V electrolytic, which could be swapped for a fancier polypropylene film.

The worst component is the tube itself (red print) but pleasant surprises are the braided 20' 7 pin cable and a very hefty high-quality shockmount, better than most aftermarket options and usable with many of these LDC bases. A leatherette wallet, no wood box, but an upgraded power supply taller than the old 460 variants, with largely the same circuit inside. Handsome dark silver headbasket with quite open double mesh, no need to pry that out. The ring at the top sorta gets in the way but sorta doesn't.

A better tube helps some, but I wanted to try the popular mod options on this platform, so I yanked C9/C10 as usual, and placed a 220K resistor over the output transformer primary. Tuning the voicing, the capsule has the typical Chinese 67 hyped tone, and I settled all the way up at 470pf de-emphasis cap (between T1 and ground) and taking T3 cathode bypass cap down to 4.7uF from 100uF. Warming up the bias with a lower resistor just made things more muddy, so I stayed at 2.7K.

Desperate to pour more energy into the absent mids I found that going a notch or two toward omni on the pattern selector helped enormously, and may help you even if you don't mod the mic. Not sure if this is the capsule or the circuit as a whole that's benefitting from this. The de-emphasis I added helps a lot, as you move toward omni you'll need to turn down your treble EQ and up your gain a bit. The null in the figure 8 was strong and even, suggesting both sides of the capsule were healthy. Well...for what it is. Teflon ring, center terminated, the usual.

With a nice tube (6072 to 12Ax7 range all work OK) I could kinda live with this, but it still sounds cheap, so I buffed off the logo with some acetone and will gut this into a much more high end circuit with a new capsule and transformer, which was the plan all along. There's isn't much room in there (45x90mm) but I can work, and the look and components once again are very sharp if you dig the modern thing.

For someone just wanting a decent mic at a good price, yes, this is about as good as you can do for this price in general. Great look and components and a solid build. Don't mind me I'm a bit picky with these things."


LC-200 review by Peter J:
"
Transformer-balanced output
This mic is quite well built and spec'd, with the multipattern "RK 87" capsule (inset brass slot screws in a white plastic ring) and a transformer-balanced output. Making it a direct competitor of the 400-level AKG Perception line. This one has nice through-hole components with a polystyrene input capacitor feeding a K170 JFET. Dual-mesh, small 47-style headbasket, three switches for pattern, pad and low cut. Body a bit lightweight but solid and could be weighted with adhesive wheel weights. Not bad in design.

In practice? The transformer is a quite low 1.85:1 turns ratio, well below the U87's 9.5:1, so a U87 this ain't. But it's there and a nice touch (The LTM500 output transformer is a whopping 17.5:1). Also apparently absent is any de-emphasis measure, the mic is very bright and could use a darker capsule. Overall not nearly as impressive as the tube LTM500 which is a genuine steal from Monoprice. But this price is low enough it's hard to source all these parts...including a very nice 22m threaded shockmount, wallet and case...for the money.

I bought it open box and within an hour already had it stripped down and the capsule backplates isolated. Not sure what I'll do with the transformer, maybe try it backwards as a step-up for a dynamic mic. The capsule and switch set will go into a vintage 87 style body and circuit with negative feedback to tame the highs, and the LC200 body will be turned into a baby Sphere with dual output, which it kinda looks like. To pair with the LTM500 which I already did all this to, turning its power supply into an unregulated U47 supply with a nip tuck to the PCB.

For those just looking for a good deal on mics, try to stretch for the LTM500 tube version. Far better sound even without any mods, and you can refine it with the 9 pattern dial. But this LC200 mic is a nice components kit for the tinkerer, and competitive within its price range in general.

"

Gus

Re: Monoprice LTM500 Tube Mic
« Reply #7 on: December 06, 2020, 11:34:36 AM »
how safe is to order from Monoprice?

Re: Monoprice LTM500 Tube Mic
« Reply #8 on: December 06, 2020, 12:16:34 PM »
how safe is to order from Monoprice?

Very. They're local to me (southern CA) and we've used their various audio/visual gadgets and cables at my work for years, and have had great luck. They're actually a fairly small operation who source direct from manufacturers in China and elsewhere. They've been growing over the last 10 years or so and seem to have a knack for getting prices down while maintaining quality where it counts (within reason of course). Their pro Audio game has been a little weak, but with the "Stage Right" line it looks like they're working on improving that. I don't work for them, but have been a customer for a while and would certainly recommend ordering direct from them. I've never had to return anything, so I can't speak to that, but I've picked stuff up in person and that experience was positive, as were shipped orders. You can find their stuff on Amazn too, but it's usually a few $ more expensive for no good reason.

kingkorg

Re: Monoprice LTM500 Tube Mic
« Reply #9 on: December 06, 2020, 01:11:17 PM »
Looks like a nice body for a C800 project.


 

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