Classic Audio MC Pro Phonostage Review

[sq225917]

Michael, I notice the snr is given for a 0.5mv 10 ohm cartridge, does such a thing exist? All the ones I can see around 0.5mV are measured at 5cm/sec and have higher coil winding resistance. Like the AT ART9Xi which measures 12ohm so 20% higher impedance, and 40% lower output at the more typically given 3.5cm/ second. Or the suiko songbird at 28ohms.

How would a real world cart affect snr performance?

 

[Michael Fidler]

@Michael Fidler Any chance you'll be sending a MM Pro to @amirm for review?

At some point perhaps, although I'm sure our man is quite tied up already with his gardening and very substantial contributions to this forum and the world of audio in general. There's probably a big backlog of stuff to test and I already have another unit in the queue - but the MM Pro could definitely be the next one after that as it's been mentioned a fair few times already. I can confirm on my end that the distortion and frequency response measurements would be much the same as those in this thread, though.

 

[Michael Fidler]

Michael, I notice the snr is given for a 0.5mv 10 ohm cartridge, does such a thing exist? All the ones I can see around 0.5mV are measured at 5cm/sec and have higher coil winding resistance. Like the AT ART9Xi which measures 12ohm so 20% higher impedance, and 40% lower output at the more typically given 3.5cm/ second. Or the suiko songbird at 28ohms.

How would a real world cart affect snr performance?

0.5mV is a pretty often quoted figure due to its roundness, and there are quite a few carts out there that hover around the 10 ohm mark. If you have a high coil resistance, then that changes the thermal noise generated by the cartridge itself (before any preamp is connected) by an proportional to the square root of the impedance ratio - i.e. a 40 ohm coil generates twice the noise voltage of a 10 ohm one.

A 12 ohm coil would generate 0.8dB more thermal noise than a 10 ohm one, but when we add calculate that in terms of the overall noise performance of the MC Pro with a 6dB noise figure, that increase only affects the total by about 0.2dB, which is pretty much below the threshold of measurement. The stated SNR on the site is at least 1dB worse than the actual measured performance of almost all production units to give some leeway on test, so it's not really significant in the grand scheme of things. The figure itself was derived from a test with a real MC cartridge load in any case.

For something like a 28 ohm cartridge resistance, you would probably see a drop in SNR of about 4dB (floor will rise about 3dB and the insertion loss will drop you another dB).

 

[exponent_of_sock]

My two cents about the subsonic filter is that I have 78s from the late 1920s with low frequencies as low as 32 Hz. I don't deal with LPs much, but I'm guessing there's quite a bit of content between 20 and 30 Hz. I think the filter on this is fine for reasons others have stated because this is a listening unit, but if I was archiving I'd want to use something with no filter and take care of any post-processing digitally to ensure accurate capture of all the deep bass.

Slight tangent--a bit of unsolicited feedback for the upcoming SPARTAN 78 phonostage--looks like a pretty good value for a 200 GBP unit, but it would be nice for budget collectors if there was a more robust and slightly more expensive unit with knobs for turnover and rolloff, a true flat setting, and stereo for archiving both groove walls. One EQ knob means that there are a great many records for which a listener couldn't get accurate EQ. I'm not in need of one, but other than the Puffin there aren't really any good 78 RPM EQs for under $3,000. Most shoehorn you into mono or have otherwise limiting designs. I think for a lot of collectors this unit will be a minor miracle compared to using their RIAA stereo receiver and tone controls, but for anyone slighlty more sophisitcated, they'll eventually be left wanting more and have not many other quality options.

 

[MaxwellsEq]

My two cents about the subsonic filter is that I have 78s from the late 1920s with low frequencies as low as 32 Hz. I don't deal with LPs much, but I'm guessing there's quite a bit of content between 20 and 30 Hz

That's something I wasn't aware of. What sort of content is it? Is it for specialised encoding or recordings given most acoustic instruments (other than organ and orchestral bass drum and some pianos) produce very little in the way of sound at those frequencies.

 

[exponent_of_sock]

That's something I wasn't aware of. What sort of content is it? Is it for specialised encoding or recordings given most acoustic instruments (other than organ and orchestral bass drum and some pianos) produce very little in the way of sound at those frequencies.

Fats Waller recorded several organ records for Victor, and the bass is quite robust and crisply-recorded there. Those records make my subwoofers sing! I would think a lot of classical and electronic LPs have good bass between 20 and 30 Hz.

 

[ban25]

Fats Waller recorded several organ records for Victor, and the bass is quite robust and crisply-recorded there. Those records make my subwoofers sing! I would think a lot of classical and electronic LPs have good bass between 20 and 30 Hz.

FWIW, I think collecting and playing 78s is what got Michael into making phono stages in the first place!

 

[MaxwellsEq]

Fats Waller recorded several organ records for Victor, and the bass is quite robust and crisply-recorded there. Those records make my subwoofers sing! I would think a lot of classical and electronic LPs have good bass between 20 and 30 Hz.

For most acoustic recordings that lack organ, some pianos and orchestral bass drum, there is very little music content at those frequencies. There is traffic noise, HVAC, construction noise etc. Some argue that it should be filtered, but I tend to think it's part of the performance (even if the composer didn't intend it).

 

[EJ3]

For most acoustic recordings that lack organ, some pianos and orchestral bass drum, there is very little music content at those frequencies. There is traffic noise, HVAC, construction noise etc. Some argue that it should be filtered, but I tend to think it's part of the performance (even if the composer didn't intend it).

Audio Frequencies​

A list of frequencies generated by things that make noises - like humans and musical instruments - but other stuff as well. As well as the fundamental frequency, most instruments have harmonics and overtones which are noted where known. But assembling this stuff is both tedious and incredibly difficult (it is unknown in some cases, horribly contentious in others or just buried in some obscure place even the search engines can't find). If you can add information use the links at the top or bottom of the page to email us. The world will be grateful. That's it. Grateful.

Note: We are now crediting reader input. Apologies to all previous contributors for the grievous oversight. Table augmented by contributions from - Thomas Wildman - many thanks.

Keyboard Instruments
Instrument	Fundamental	Harmonics	dB(SPL)	Notes
Piano	A0 (28 Hz) to C8 (4,186 Hz or 4.1 kHz)		60 - 100
Organ	C0 (16 Hz) to A9 (7,040 Hz)		35 - 110	some are said to be capable of C-1 (8 Hz)
Wind - without a reed
Instrument	Fundamental	Harmonics	dB(SPL)	Notes
Concert Flute	C4 (262 Hz) to B6 (1,976 Hz)			Some start at B3 (247 Hz)
French Horn	A2 (110 Hz) to A5 (880 Hz)
Picolo	C5 (523 Hz) to B7 (3,951 Hz)
Trombone
Tenor	E2 (82 Hz) to D5 (587 Hz)			Exceptionally F5 (698 Hz). Bb fundamental, sometimes F.
Contrabass	E1 (41 Hz) to E4 (330 Hz)			F fundamental, sometimes Bb.
Bass	C1 (33 Hz) to C5 (523 Hz)			Can start around Bb0 (A#0 - 29Hz). Bb fundamental.
Trumpet	E3 (165 Hz) to B5 (988 Hz)		55 - 95
Tuba (Bass)	F1 (44 Hz) to F4 (349 Hz)			Many play around Bb0 (A#0 - 29Hz)
String Instruments
Instrument	Fundamental	Harmonics	dB(SPL)	Notes
Violin	G3 (196 Hz) - G7 (3,136 Hz) (G-D-E-A) (or C8 (4,186 Hz?)	to 10 kHz	42 - 95
Viola	C3 (131 Hz) - D6 (1,175 Hz)
Cello	C2 (65 Hz) - B5 (988 Hz (C5))	to 8kHz
Double Bass	E1 (41 Hz) to B3 (247 Hz)	7kHz
Guitar (Acoustic)	E2 (82 Hz) to F6 (1,397 Hz)			Standard tuning of E A D G B E. (Open #6 82.407Hz, Open #1 369.63Hz, #1 25th Fret 1,396.91Hz (1.39 KHz)
Guitar (Bass)	4 string E1 (41 Hz) to C4 (262 Hz).	15kHz.		5 string Bass normally starts at B0 (31 Hz) but tops out at the same C4 value.
Guitar (Electric)	E2 (82 Hz) to F6 (1,397 Hz) (Open #6 82.41 Hz (E2), Open #1 369.63 Hz (E4), #1 25th Fret 1,396.91 Hz (1.39 kHz) (F6)		Unlimited!	Same range as for acoustic guitars but electric guitars have more harmonics and effects and these can go way over 20kHz. But, since you cannot hear them (unless you claim to be an audiophile) - who cares.
Note: When using a slide with a guitar the note frequency at any single fret position does not change from that produced by a finger but the instrument's timbre does, due to the reduced dampening effect of the slide over the human finger. In particular, the sustain (of the ADSR envelope) is much longer and there is more power in the higher harmonics. This latter effect may give the impression the note has a higher frequency. Slide technique, however, typically involves moving the slide back and forth on the frets to literally slide from one note to another thus continually changing frequency to produce its distinctive effect.
Percussion Instruments (things you hit)
Instrument	Fundamental	Harmonics	dB(SPL)	Notes
Drums (Timpani)	90Hz - 180Hz
Bass (Kick) Drum	60Hz - 100Hz		35 - 115	Some sources quote a low of 30Hz
Snare Drum	120 Hz - 250 Hz
Toms	60 Hz - 210 Hz
Cymbal - Hi-hat	3 kHz - 5 kHz		4 - 110
Xylophone	700 Hz - 3.5 kHz
Wind (Reed or Woodwind) Instruments
Instrument	Fundamental	Harmonics	dB(SPL)	Notes
Bandoneon	Descant (right) side G3 (196 Hz) to A6 (1,750 Hz). Bass (left) side C3 (131 Hz) to A5# (932 Hz)
Clarinet	E3 (165 Hz) to G6 (1,568 Hz)			C7 sometimes possible (2,093 Hz)
Saxophone
Tenor	G#2 (104 Hz) to E5 (659 Hz)			Bb fundamental.
Barritone	C2 (65 Hz) to A4 (440 Hz)			Eb fundamental.
Humans (You and me - well, sometimes in our case)
Instrument	Fundamental	Harmonics	dB(SPL)	Notes
Hi-Fi	50 Hz - 15 kHz			Originally thought to be the range of human hearing, and still may be depending on your age. Now revised as shown below.
Human Hearing	20Hz - 20kHz.			Unless you spent a lot of your adolescence in a disco or club in which case it is now probably squat. Audiophiles are supposed to be able to hear above 20KHz - or perhaps they only think they can. Over the age of 50 (some research suggests it may be even lower than that) most people are limited to a range of ~50 Hz to 15/16 kHz.
Hearing Sensitivity	300hz - 5 kHz			Humans are not uniformly sensitive to sound across the frequency spectrum. The most sensitivity is from approximately 300 Hz to 5 kHz with a particularly sensitive spot round 2 - 4 kHz (this phenomenon is described by the Fletcher-Munson curves). This means that for many instruments we can be more sensitive to the effects of the 2nd, 3rd or higher harmonics (and equivalent overtones) not the fundamental. A doubling in sound power/energy results in a 3 dB(SPL) increase, 10 times power sound power/energy results in 10 dB(SPL) increase but humans preceive 10 dB(SPL) as only double the loudness.
Sound Power			dB(SPL) rating for some common sounds. 10 - leaves rustling in a breeze 20 - whisper 30 - quiet conversation 50/55 - ambient office 70 - city street 80 - noisy office 100 - pneumatic drill (at 3m or 10 feet) 120 - jet take off 120 - pain threshold (See also Loudness and Sound Power)
Soprano	C4 (262 Hz) to C6 (1,047 Hz).
Mezzo-Soprano	A3 (110 Hz) to A5(880 Hz) (exceptions G3 (196 Hz) to C6(1,047 Hz))
Contralto	F3 (175 Hz) to F5 (698 Hz)
Countertenor	Male voice. Normally sings in the Contralto or Mezzo-Soprano range - exceptionally the soprano range.
Tenor	C3 (130 Hz) to C5 (523 Hz)			F5 (698 Hz) as extreme
Baritone	F2 (87 Hz) to F4 (349 Hz)
Bass	F2 (87 Hz) to E4 (330 Hz)	Harmonics to 12kHz

Frequencies, Harmonics and Under Tones​

This table was conributed by DJ Adi Abhishek. It is the most comprehensive we have ever seen and must have taken enormous work to put together. A truly remarkable (IOHO) piece of work.

The terms Under and Over tone are explained here. Ali quotes a frequency range for most sounds (different manufacturers, human characteristics) and then uses a single Fundamental Frequency for calculation of Under and Over tones.

We have made minor editing changes to Ali's originally supplied table and one significant change. The significant change is that the column headed Harmonics (2nd - 6th) was originally labelled Harmonic Over Tones. We made the change since, as harmonics, they all represent integer multiples of the Fundamental Frequency (a.k.a. 1st Harmonic). Overtones are not always integer multiples.

SOUND	FREQUENCY RANGE	FUNDAMENTAL FREQUENCY	HARMONICS (2nd - 6th)	HARMONIC UNDER TONES
Kick Drum	60	250	155	310	465	620	775	930	77.50	51.67	38.75	31.00	25.83
Toms	60	210	135	270	405	540	675	810	67.50	45	33.75	27.00	22.50
Snare	120	250	185	370	555	740	925	1110	92.50	61.67	46.25	37.00	30.83
Cymbal/Hi-hat	3000	5000	4000	8000	12000	16000	20000	24000	2000	1333.33	1000.00	800.00	666.67
Electric Guitar	82	1397	739.50	1479	2218.50	2958	3697.50	4437	369.75	246.50	184.88	147.90	123.25
Bass Guitar	41	262	151.50	303	454.5	606	757.50	909	75.75	50.50	37.88	30.30	25.25
Acoustic Guitar	82	1397	739.50	1479	2218.50	2958	3697.50	4437	369.75	246.50	184.88	147.90	123.25
Mandolin	136	1320	728	1456	2184	2912	3640	4368	364	242.67	182.00	145.60	121.33
Tenor Sax	104	659	381.50	763	1144.50	1526	1907.50	2289	190.75	127.17	95.38	76.30	63.58
Alto Sax	150	800	475	950	1425	1900	2375	2850	237.50	158.33	118.75	95.00	79.17
Harmonica Various	180	3100	1640	3280	4920	6560	8200	9840	820	546.67	410.00	328.00	273.33
Vocal (Baritone)	87	349	218	436	654	872	1090	1308	109	72.67	54.50	43.60	36.33
Vocal (Tenor)	130	523	326.50	653	979.50	1306	1632.50	1959	163.25	108.83	81.63	65.30	54.42
Vocal (Alto)	180	700	440	880	1320	1760	2200	2640	220	146.67	110.00	88.00	73.33
Vocal (Soprano)	250	1300	775	1550	2325	3100	3875	4650	387.50	258.33	193.75	155.00	129.17
Violin	196	4186	2191	4382	6573	8764	10955	13146	1095.50	730.33	547.75	438.20	365.17
Viola	315	1175	745	1490	2235	2980	3725	4470	372.50	248.33	186.25	149.00	124.17
Cello	65	988	526.50	1053	1579.50	2106	2632.50	3159	263.25	175.50	131.63	105.30	87.75
Double Bass	41	247	144	288	432	576	720	864	72	48	36.00	28.80	24.00
Piccolo	523	3951	2237	4474	6711	8948	11185	13422	1118.50	745.67	559.25	447.40	372.83
Flute	250	2500	1375	2750	4125	5500	6875	8250	687.50	458.33	343.75	275.00	229.17
Oboe	225	1500	862.50	1725	2587.50	3450	4312.50	5175	431.25	287.50	215.63	172.50	143.75
Clarinet	165	1568	866.50	1733	2599.50	3466	4332.50	5199	433.25	288.83	216.63	173.30	144.42
Accordion	180	1000	590	1180	1770	2360	2950	3540	295	196.67	147.50	118.00	98.33
Bassoon	60	620	340	680	1020	1360	1700	2040	170	113.33	85.00	68.00	56.67
Trumpet	165	988	576.50	1153	1729.50	2306	2882.50	3459	288.25	192.17	144.13	115.30	96.08
Trombone	60	500	280	560	840	1120	1400	1680	140	93.33	70.00	56.00	46.67
French Horn	110	880	495	990	1485	1980	2475	2970	247.50	165	123.75	99.00	82.50
Tuba (Bass)	44	349	196.50	393	589.5	786	982.50	1179	98.25	65.50	49.13	39.30	32.75
Harp	30	7000	3515	7030	10545	14060	17575	21090	1757.50	1171.67	878.75	703.00	585.83
Harpsichord	40	1500	770	1540	2310	3080	3850	4620	385	256.67	192.50	154.00	128.33
Piano	28	4186	2107	4214	6321	8428	10535	12642	1053.50	702.33	526.75	421.40	351.17
Pipe Organ	16	7040	3528	7056	10584	14112	17640	21168	1764	1176	882.00	705.60	588.00
Keyboard / Synth	20	4000	2010	4020	6030	8040	10050	12060	1005	670	502.50	402.00	335.00
Female Voice	250	1000	625	1250	1875	2500	3125	3750	312.50	208.33	156.25	125.00	104.17
Male Voice	100	800	450	900	1350	1800	2250	2700	225	150	112.50	90.00	75.00
Sub Bass	16	60	38	76	114	152	190	228	19	12.67	9.50	7.60	6.33
Concert Flute	262	1976	1119	2238	3357	4476	5595	6714	559.50	373	279.75	223.80	186.50
Xylophone	700	3500	2100	4200	6300	8400	10500	12600	1050	700	525.00	420.00	350.00
Timpani (Drum)	90	180	135	270	405	540	675	810	67.50	45	33.75	27.00	22.50
Contra Bass	41	330	185.50	371	556.50	742	927.50	1113	92.75	61.83	46.38	37.10	30.92
Bass	33	330	181.50	363	544.50	726	907.50	1089	90.75	60.50	45.38	36.30	30.25
Baritone Sax	65	440	252.50	505	757.50	1010	1262.50	1515	126.25	84.17	63.13	50.50	42.08
Soprano	262	1047	654.50	1309	1963.50	2618	3272.50	3927	327.25	218.17	163.63	130.90	109.08
Mezzo Soprano	110	880	495	990	1485	1980	2475	2970	247.50	165	123.75	99.00	82.50
Contra Alto	175	698	436.50	873	1309.50	1746	2182.50	2619	218.25	145.50	109.13	87.30	72.75

 

[EJ3]

I did want to emphasize this from the charts that I provided:

​

				A doubling in sound power/energy results in a 3 dB(SPL) increase, 10 times power sound power/energy results in 10 dB(SPL) increase but humans perceive 10 dB(SPL) as only double the loudness.

 

[Michael Fidler]

The SPARTAN 78 is not intended to by an all-singing-all-dancing archival/monitoring unit with multiple outputs and endless EQ combinations - rather a practical and cost-effective way for people to start listening to their discs. Therefore a whole pile of complication would increase the price and make it a less unique and accessible product among the ranks of many others. It needs to be as simple and effective as possible.

I have built quite a few 78 RPM preamps, ranging from flat-level devices in 2010/11, to all kinds of complicated designs that feature multiple knobs on the front panels for all three turnover points, plus variable LF and HF cut-off points for filtering. One of which you can find from 2014 from when I was still a teenager...

https://www.diyaudio.com/community/...ticurve-phono-preamp-for-your-shellac.256771/

I've found the more complicated designs much less fun to use for the simple task of listening to discs (not archiving, for which you want either flat or RIAA), so I don't see any reason to make the entry point even harder and more confusing for the listener. You just want to be able to turn a knob and maybe flick a switch to set the bandwidth and be ready to listen. It's actually the case that the vast majority of discs can be equalised to a highly satisfactory degree with just a few curves for the purposes of listening. Most of the info on EQ out there on the web is rubbish and only a few characteristics are really required. I would even go as far as to say that the 4 middle settings are all that I use in practice, as I very rarely listen to acoustic-cut discs as they're not very enjoyable due to the very poor fidelity.

In case you're wondering, I don't use any of my old designs in-situ anymore and have been using this simple preamp for my listening since at least 2022 when I made the first prototype. Simple is better when you just want to listen!

 

[MaxwellsEq]

I think you are certainly more likely to make a profit with a simple device that sounds excellent with 80% of the discs out in the wild. You could always offer a bespoke build to museums and other archivist where you don't amortise the cost of development and build across many units, but this will be costly to anyone buying it!

 

[Michael Fidler]

I think you are certainly more likely to make a profit with a simple device that sounds excellent with 80% of the discs out in the wild. You could always offer a bespoke build to museums and other archivist where you don't amortise the cost of development and build across many units, but this will be costly to anyone buying it!

I was considering something a bit fancier, like a '78 PRO' but now I'm leaning towards as 'FL PRO' that I have sketched out for something a bit more pricey - a flat preamp with balanced outputs and possibly parts of this design for monitoring. If you're already archiving, then you have access to DSP for more advanced monitoring/processing and all that more complicated analogue shaping isn't really necessary.

Like you said, the market is lacking something relatively inexpensive and easy to use. I know a lot of people who listen all the time are using old Quad 33s as the hi-cut function is very handy, so really it has to be something about the same price. I would go a bit further and say at least 95% of discs will be good with the curves provided. I've got a few thousand 78 RPM discs and they all have a nice natural balance with the appropriate setting.

 

[JP]

I was going to say, I think most archivists have moved on to DSP... and if they haven't, they certainly should. Wayne Kirkwood did a nice balanced flat/monitor system geared toward cutters.

 

[Michael Fidler]

I was going to say, I think most archivists have moved on to DSP... and if they haven't, they certainly should. Wayne Kirkwood did a nice balanced flat/monitor system geared toward cutters.

You're absolutely right - flat recording into DSP, then you can apply all the EQ you like with endless variability and spit it out of the other end through a DAC for monitoring.

All those archival preamps are almost certainly obsolete by now, although I'm sure many are still being used for transfers in various archival businesses I doubt that there's any further market for them. Listening to these discs as a hobby maybe has quite a bit more mileage in it!

 

[exponent_of_sock]

I was considering something a bit fancier, like a '78 PRO' but now I'm leaning towards as 'FL PRO' that I have sketched out for something a bit more pricey - a flat preamp with balanced outputs and possibly parts of this design for monitoring. If you're already archiving, then you have access to DSP for more advanced monitoring/processing and all that more complicated analogue shaping isn't really necessary.

Like you said, the market is lacking something relatively inexpensive and easy to use. I know a lot of people who listen all the time are using old Quad 33s as the hi-cut function is very handy, so really it has to be something about the same price. I would go a bit further and say at least 95% of discs will be good with the curves provided. I've got a few thousand 78 RPM discs and they all have a nice natural balance with the appropriate setting.

I agree that your choices for the Spartan 78 are great for beginners and casual listening. I think it would even work fine for most acousticals. Acousticals can sound great with careful restoration, but it requires a lot of experience. The hardcore listening-only 78 collectors make liberal use of graphic EQs for acousticals. I generally agree with the -7 rolloff curve and that most of the published EQ curves are bunk. The early electricals have flat treble and really bright microphones with peaks around 3 kHz, and -7 is a rougly-accurate compromise. -5 is mostly nonsense. Actually-accurate results requires complex DSP EQ curves that need to be tuned by ear for every record, and the same with bass curves. 250/300/500 is generally a crude approximation and the real recordings aren't a simple 6 dB/octave curve.

I wish this had been available when I was just starting out, because the KAB Souvenir I did have was very poorly engineered. Even when the noise removal circuits were turned off, they massively colored the sound, or there was some other design flaw that massively impacted the transparency. I didn't realize it until I got rid of it.

I like the idea of your future FL Pro product. Although the 78 community is small, I could see there being a niche market for it. You're probably aware of Dave Cawley's Timestep T-03 units which go for around $3k. Not exactly sure if he's still making them. I don't keep the best tabs on what's out there, but I think that's the only real analog archiving-grade preamp out there better than the Parks Waxwing. I've had one, but my friend who knows much more about amp design said it's somewhat value-engineered. I'm now using the $14,000 Millennia LOCi, but just the flat preamp--kind of overkill, but I got a good deal on a used unit. I do everything else digitally in CEDAR Cambridge. There's a lot of stuff you could put in a higher-end archiving preamp like mono/stereo, vertical/lateral, various turnover and rolloff curves, groove wall panning, various gain settings. With my CEDAR computer, I only need the gain settings. Everything else is wasted. I think you'd probably want to build a lot of this into a future FL Pro, though, because archivists don't all have the most sophisticated digital tools for the initial transfer.

 

[JP]

Listening to these discs as a hobby maybe has quite a bit more mileage in it!

For most, probably. I moved to DSP EQ in my playback chain almost a decade ago, so for me it's loading a set of biquads in to a preset. One of the reasons I appreciate the availability of flat phono stages.

 

[WDeranged]

I'm still exceptionally pleased with my Spartan 15. It's so transparent I often forget that I bought it. I hope Amir reviews it one day.

 

[ryanmh1]

What is astonishing to me is how reasonable the parts count appears to be, and fairly simple the circuit, yet how thoroughly this absolutely stomps most of the rest of the market by a meaningful amount. It would be interesting to try to compile a list of MC stage noise levels. I could not find anything that topped this by any meaningful amount, and this is arguably one of the few areas left where we really have not "got the noise out" yet. Has anyone applied an IHF-A filter to this yet? Some of the vintage Yamaha units topped the market by a significant margin back then. It's not directly comparable to an unweighted measurement, but it would be interesting to see how this stacks up on the old IHF-A spec.

 

[gjm]

What is astonishing to me is how reasonable the parts count appears to be, and fairly simple the circuit, yet how thoroughly this absolutely stomps most of the rest of the market by a meaningful amount. It would be interesting to try to compile a list of MC stage noise levels. I could not find anything that topped this by any meaningful amount, and this is arguably one of the few areas left where we really have no "got the noise out" yet. Has anyone applied an IHF-A filter to this yet? Some of the vintage Yamaha units topped the market by a significant market back then. It's not directly comparable to an unweighted measurement, but it would be interesting to see how this stacks up on the old IHF-A spec.

Simple, well-designed kit built with quality parts does perform very well. (Proof evident from Michael!)