RMGI SM911 vs SM468 - Noise Levels and EQ

[vf_marshall]

Good evening Tapeheads!

Had a play around with RMGI's SM911 and SM468 tonight which included complete alignment of two machines (Teac X1000 and Philips N4520) for both tape formulations. I found that the SM911 was exibiting a lot more tape hiss than the 468 (no noise reduction) for both machines, although the overall response was very similar on test tones which surprised me. Both machines were run at 7.5ips with NAB EQ.

Looking though the RMGI pdf for SM911, it looks like the tape is better suited for 15ips and above, so just for fun I run the same tests on the Philips at 15ips, with NAB EQ and the noise level reduces a small degree but really drops dramatically at the IEC EQ setting.

All this makes me wonder if 911 is just a bit too 'good' for this type of machine (most of my recordings are made at 7.5ips) while the SM458 seems to be a lot quieter at the lower speeds. The bias requirements for SM911 seem to about 1.5db less than SM468. I was wondering if anyone else on here has had a play around with both formulations and can add any experiences?

Incidentally, neither tapes seem to be shedding oxide as reported by others on here.

[Lance Lawson]

I am as ever envious of anyone who runs new tape without issue. My last ditch stand for my TEAC will have to be LPR 35. If that won't work then my TEAC becomes decoration.

[vf_marshall]

I am as ever envious of anyone who runs new tape without issue. My last ditch stand for my TEAC will have to be LPR 35. If that won't work then my TEAC becomes decoration.

That would be a real shame to mothball that lovely old Teac, I've not tried LPR35 but I've heard really good things on here and elsewhere about it. Will the Teac not bias up the modern formulations correctly?

[Skywavebe]

Hello Vf,
It will bias up correctly but the problem is the terrible boost at 7.5KHz for the old tape formulas that gets in the way and it needs to be corrected otherwise you end up trying to satisfy the 7.5KHz level within 3 dB and that is done by over bias of the new tape which causes the high end above the EQ boots to be rolled off tremendously. If you want a deck that can do 40 to 12KHz then leave the EQ alone but I have gotten them out to 24KHz with the modification. The machine was built with 3M 203 tape in mind.

[Skywavebe]

Oh, Lance,
In the first few lines of the test it stated that the machines were freshly calibrated and aligned. This is what you machine needs as well as the mod.
Then the new tapes of today will be a lot better sounding. I have not had anyone bring a machine back in all the years I have been doing this and they generally say they like the way it sounds.

[vf_marshall]

Hello Vf,
It will bias up correctly but the problem is the terrible boost at 7.5KHz for the old tape formulas that gets in the way and it needs to be corrected otherwise you end up trying to satisfy the 7.5KHz level within 3 dB and that is done by over bias of the new tape which causes the high end above the EQ boots to be rolled off tremendously. If you want a deck that can do 40 to 12KHz then leave the EQ alone but I have gotten them out to 24KHz with the modification. The machine was built with 3M 203 tape in mind.

Hi Sam,

I guess that the play/record eq boards won't have trimmers to adust the HF on the older teac? Unfortunately my Philips is the same in that respect, although it does seem to play my MRL tape reasonably flat up to 20khz (+/- 2db) without too much drama.

In the case of Lance's Teac, would you replace fixed value resistors in the play/record EQ circuit with trimmers that can be tweaked to flatten out the frequency response? Just curious really!

Thanks again, Vic

[Skywavebe]

Hi Vic,
No, I don't put in variable where regular composites are in general and certainly not in this case. This is a case where the amount of frequency boost is dictated by a Mylar capacitor which is too large. In terms of the cap value you read on them it might be 153J so the caps I find myself putting in
to lessen this boost is a smaller value and it is not fixed but can range from 392 to 562 and sometimes as low as 102 in value. These are the values that are stamped on the caps- usually green colored that Teac used that indicate
value in uFd so a .1 uFd cap would be noted as a 105 which means 1 followed by 5 zeroes. A 1 uFd cap would be 106 but they do not note those in that nomenclature. I hope this makes sense to you in some way. The mod is not a big deal but sometimes to get to where it is best you have to try two or three caps. The playback stays as per normal test tape alignment.

[vf_marshall]

Thanks very much for the detailed reply, Sam. After studying the EQ circuit diagram for the Philips, I can see which caps you would be referring to (no plans to modify my own machine at this stage). It's surprising that manufacturers back in the day would fix these component values to save a few £$, although I guess at this consumer/prosumer end of the market it's not so critical to most owners.

All this great information does mean that Lance's Teac could be modified to run with a modern formulation without too much drama too *Hi5*

One last thing Sam, in your experience, would you suggest that a high end studio tape on a consumer narrow track machine at lower speeds (thinking SM911) is not ideal?

[Lance Lawson]

Oh, Lance,
In the first few lines of the test it stated that the machines were freshly calibrated and aligned. This is what you machine needs as well as the mod.
Then the new tapes of today will be a lot better sounding. I have not had anyone bring a machine back in all the years I have been doing this and they generally say they like the way it sounds.

I had no problem with the sound of 468. My problem is a tracking issue that very well may be aggravated by the substantial thickness of the 468 as well as it's width. On the occasions where the tape and machine were "behaving" the 468 sounds quite nice. But I have my fingers crossed that LPR35 will run better.

Pity I seem to have the only TEAC on the planet with this issue*dunno*

[PioneerRT-2022]

Hi, I am new to the forum, but not to reel to reel or tapes. I have tried them all and this is the order in which I like them SM900 being the best, then SM468 and then the SM911. The SM 468 was my preferred( less brittle and more stable) tape until I tested the SM900 with my pioneer RT-2022. Of course I had to calibrate the machine for this tape, but it wasn’t complicated at all.

This tape can be driven to +9 with no distortion whatsoever. The results are very high output, very low noise and wider dynamic range when I compare it with the other tapes, can’t go wrong with this tape. My settings on this machine are LH, Variable Bias and at 7.5 ips, there is not need for more speed with my machine. The SM900 needs a little bit more bias than the other two formulations

This machine makes it easy, since it is a 2 track 2 channel and has the very convenient variable bias settings. Any tests with this tape(SM900)?, I would like to hear from anyone about this tape and what you think about it.

In general these tapes are excellent, never had any problems regarding poor quality or shedding

[Lance Lawson]

In general these tapes are excellent, never had any problems regarding poor quality or shedding

I have two reels of 1200' 468 unused. If you'r interested PM me. 468 does not run well on my TEAC. But glad you like it.

[PioneerRT-2022]

Thank you for the offer, really appreciate that. I like the SM468 a lot, but when I tried the SM900, that was it. I adjusted my machine for the SM900 to get the most of it since is the tape I am going to use from now on. *bigthumbup* Go here http://www.youtube.com/watch?v=BPtxhAQPCHY check it out.

[shotwell]

900 is some serious tape. Awesome that your record amps are stong enough to record on it.

Once I get the heads worked on my Tascam 42 I'll probably be looking at SM900, or at least 911.

[PioneerRT-2022]

I agree, it is a very serious tape and for me the best of all. I bought a good amount of them from a closeout sale, they come in black plastic reel( is the one I have in my avatar picture), they look great. They are extremely well balanced and since I don’t have to use Hubs Adapters with them they don’t move up or down.

I bough a lot of them in order to get the best possible price( I was lucky they sent me one for me to test before buying the lot) and I am willing to sell a few if you or someone else is interested at a very, very good price. Check the link from the previous post so you can see me testing this tape. PM me for more detail*reelspin*

[shawn]

I finally have all RMGI made tapes. SM 900, SM 911, LPR 35 AND finally SM 468. My Akai 747 has been calibrated to Quantegy 456 thats the same bias for SM 911. Also SM 468 is the same bias right? SM 468 is in line with Quantegy 406/407 right? Anyway SM 900 sounds the best with my UV meters going past +5 with no distortion. The only thing is when you erase on it it does not get erased totally, I have to erase it a couple of times to get it off completely. SM 911 gets erased in one go. The best part is I have yet to find a RMGI tape that is shedding. I have 15 tapes from them now and I alway run the tapes 4 hours each on the 2400" and 6 hours each on the 3600" tapes before recording on them. No shedding at all. I highly recomend all the RMGI tapes that are available. Unlike the ATR ones. Worse tapes I have ever come across. 6 out of 6 including the replacements were bad. Atleast I am happy that we have one reliable tape maker.

[PioneerRT-2022]

Hey Shawn I am glad you like the SM900. All the RMGI tape formulations are excellent. The reason it is difficult to erase is because you are putting more everything to it, this tape can be drive up to +9 with no problems whatsoever, but it takes a little bit more bias the 468 and 911. The 468 is the one that required less bias. The SM900 is my favorite because it can be driven higher than other tapes; therefore, the results are with less noise( I have to be very close to the speakers to hear the hiss between tracks), more headroom and higher output.
How much are you paying for the SM900?

[shawn]

I am paying $25.62 for pancakes from Full compass. I get the 3M 996 gold reels and Basf Maxima 900 reels and put these on to them. I don't like the RMGI style reel. 3M and Basf/Emtec looks much better

[PioneerRT-2022]

Sorry to keep asking you, but where do you get the Basf Maxima 900 reel, I would be interested to get my hands on a few.

I am selling New SM900 with the black plastic reel @ $35 with free shipping to the lower 48 states, just in case someone is interested.*bigthumbup*

[shawn]

Thats ok. I get it from a guy in the LA area. He is called tapeandtape. He is selling on ebay. He is supposed to have the biggest tape stock in the US. He has all the pro tape reels that were manufactured by 3M, AMpex, Basf/ Emtec, quantegy, Agfa, Zonal etc

[PioneerRT-2022]

Thanks, I will check him out

[vf_marshall]

Did a little more testing with the two tapes today on a different deck - a Tascam 32. I've already been using SM468 on the Tascam for a few weeks but hadn't tried SM911 just yet. The 32 will happily overbias both tapes to RMGI's spec sheets, so that's a good start.

I was quite surprised at the lower noise floor of the 911 over 468 on the Tascam, a recording of Newton Faulkners 'Rebuilt by Humans' CD from my Arcam Alpha 9 CD revealed pretty much non -existant background hiss during the quieter passages, and it did 'seem' a bit more punchy and also transparent at the top end - more like the old Ampex 456 that stung most of us with its SSS!

Measurements with test tones for both tapes didn't really reveal much differences though, frequency sweeps were within +/- 2db from 30hz -> 20 Khz for both tapes which was pleasing to say the least!

I conclude that the consumer machines I own (Philips 4520, Teac x1000) don't seem capable of overbiasing the tape sufficiently, and the 1/4 track format can't reveal the full potential unfortunately.