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In Reply to: RE: rebuilt tympani posted by stansnark on February 11, 2015 at 07:53:22
Having done the mod you are thinking of and having compared to a 20.1 though in a different setting and with way more expensive gear on the 20.1, I can say that the Tympani/Neo8 was far superior in every aspect, I have not heard the 20.7 yet but I have done the Tympani/Neo8 with a first order XO (passive line level) and had no coherence issues and with an equidistant arc arrangement I got the best imaging I heard ever. The Tympani bass was definitely better than the 20.1, particularly below 40-50 hz. The midbass was more powerful on the T IV/Neo8.
you can do the Tympani/Neo8 for so much less than a used 20.7 and you can use a medium powered parallel SET since the mids will be about 96db and the ribbon is 90-91 db sensitive on its own. But you will need a 2 ohm tap to work the Neo8/ribbon section since the ribbon is <3 ohms.
Push pull DHTs can also do it with their extra power and sound fantastic on maggie ribbons. Audion and Border patrol amps and similar designs should do well, our Davy from the UK just did a Silver Night PP amp on the top section of his IIIa and was floored by the SQ and those are nowhere near as sensitive as the Neo/Ribbon combo would be.
The Marchand tube XO is what I would have taken had my budget stretched that far, but it cost 3X the SS one so I let it go and eventually went all passive line level.
Your SS Krell amps should be able to control the bass panels and have ample power into 4 ohms.
Follow Ups:
what if I tri-amp with the krell on the woofers and my se-811 on the mids ? my set is 11w and works fine on my 96db infinity compositions.what would be best on the ribbos then ? tubes ?
That sounds like a good plan. But don't knock a higher power DHT PP, they can be very good if run in class A and give a parallel SET with the same tubes a run. If you triamp then the choice of amp for the ribbon is either to be coherent with the midrange amp or to get the cleanest top octave which would be a class A SS amp with no/minimal feedback.
If you want to go with coherent tube top end you can either find a similar amp to that on the mids with a 2 ohm tap or use a Spelz autoformer.
If you triamp then the likely HF XO will be 5-6 khz which leaves the ribbon with very little to do except provide "air" and fast transient edges, which is its strength and important for imaging. The important thing is that you can probably do with just over 10 watts. Some of the First Watt designs are non feedback designs and the XM26 will be "tubey" enough to give the top end a coherent character with a SS amp ribbon amp matching the tube mid amp.
Satie; could you give a few examples of "class A SS amp with no/minimal feedback", that should be good for ribbons/mids?
The "go to" in this category are the first Watt amps from passhttp://www.firstwatt.com/prod.html
And of course Ayre, which are even more expensive.
This one looks interesting though I never heard of it
http://www.highendcity.com/the-end-millennium-power-amplifier-stereo/ available as kit as well.Son of Zen, a pass design, is also a candidate.
The regular class A (XA) Pass amps use low feedback, Most of the heavier Threshold amps and most Fosgate/Haffler/strickland (audionics) designs can have their bias upped to high bias class A but you need to have a fan added. They are reputed to not use as much feedback as most others.
The David Reich amps from Classe used moderate feedback and operated at rather high bias into class A the DR 3 and DR3 VHC are worth restoring.
Project Sphinx amps from Europe qualify,but are all old and should be recapped before use.
Also stumbled on this
http://www.monoandstereo.com/2014/12/m2-x-power-amplifier-class-amplifier-new.html
sold off ebay
Edits: 02/13/15
Do some listeners ever have times when their systems just don't sound 'right'? When that happens to me I often I conclude my Tympani IV-As are behaving wrong, or is it possibly the recording I'm currently using, or that particular recording in combination with the system/speakers?
I'd have one helluva time working with some of the above contrived contraptions. It by no means is making things as simple as they can and should be. Is it being proposed that Magnepan is to restore a set of IV-As only to have them torn apart so that a hobbyist can listen to SET amps? It seems kinda screwy to my way of thinking!
it is kind of screwy but sometimes you just can't go backwards. after the tympani's I can't go back to a box speaker, and after the set's I can't go back to a lesser midrange. so the neo-8 mods seem like the perfect solution. by the way, I had to send the maggies back to the factory because of smoke damage from a house fire that I inadvertently set myself (lol)and insurance covered everything.
I am entirely with you on this line of thinking. In my case the T IV mids were known to be not quite where they should be on resolution and speed as magnepan soon came out with the IVA version to fix it with a lighter diaphragm and longer driver. So the Neo8 drivers were more of a necessity than just a tweak. But hearing the MG20.1 convinced me that it would be a worthwhile upgrade to any maggie with which it can be integrated. The added bonus of high sensitivity allowed me to use a tube amp which is indeed a step up.
I had the T-IVa and now have the 20.1. The 20.1 just cannot do the mid bass and lower bass quality of the T-IVa. Only the 1 ohm Scintilas were able to meet (and beat) that bass quality. But the mids and up, the 20.1 have the nod. The T-IVa and the 20.1 were pretty spot on on HF as they basically have the same tweeter ribbon driver, only difference was they were spaced further from other drivers on the T-IVa, which put them slightly less favorable to me (some here would totally disagree). I like the fact that the 20.1 took up less floorspace in my room than my T-IVa (otherwise I would have kept the T-IVa and just done the Neo 8 mod to make them perfect for me)...
I VOID WARRANTIES
Not quite. The T-IVa has the same 2 ohm ribbon that the IIIa had; 20.1s have the (narrower) 3 ohm ribbon that 3.Xs have. I believe the 3 ohm ribbon sounds just a bit better than the earlier one.So that is how you take some T-IVas to the max:
1. replace each mid panel with a string of Neo8s, and
2. replace the older ribbon with the newer one (which I believe is about 1/2" longer).That is my long term plan for my 'Frankenpans' ... which are essentially T-IVas with only 1 bass panel each side. (They are made from a T-IVa mid / ribbon frame coupled with a 2.5 bass panel - but with hardwood frames, not MDF.)
Regards,Andy
Edits: 02/15/15
About the various ribbons. Originally there was a wide 3 ohm ribbon (like in my T-IVa). This was replaced by a wide 2 ohm ribbon + resistor. Maybe this to was to increase the reliablity of the ribbon? Since quite a few years, there is a narrow 3 ohm ribbon. The steel core is the same but the magnets are thicker, the slot between the magnets is about 5 mm. The older ones had a slot about 7 mm wide. Theoreticly it should be possible to use a narrow ribbon in the wide slot but sensitivity will be lower than for the ones with thicker magnets. The difference in length is 0.6", my T-IVa and my MG 3.6 have different ways of connecting them at their ends. The replacement 2 ohm ribbons have the later type of connecting blocks used today. The replacement 2 ohm ribbon came with a strange recommendation to insert the series resistor ahead of the crossover, would give a different frequency response. I think, the resistor needs to sit after the crossover just ahead of the ribbon driver. Of course, one could also use a different crossover, something like the ones used in the 20-series.
"only difference was they were spaced further from other drivers on the T-IVa", huh?,- and as you well know you could place them *anywhere* their little heart's desired!
One could never know how "perfectly" the Neo8 mod performs unless having the stock speaker in the same place and at the same time. For all I know it may destroy the 'balance' that exists in a pure Maggie, and sound dreadful. The disadvantage of a Tympani IV-A in requiring more floor space is more than overcome by being able to 'bloom' in a manner that no 20.X can, loading an entire room with glorious sound. A 20.X's sound *when* compared to the T IV-A, makes it sound more like a box speaker (not good!).
I, for one, did not like the sound of the Mid/Tweet panel separated, and stuck in front of one of the bass panels. In all honesty, I don't know why Magnepan ever advised doing so. So having them as intended, on the side of the woofer panels, they were a good 16" to 32" away from the tweeter ribbon....this is what I mean by spaced further from other drivers compared to the MG20.1. Now to have them "cupped" as Sadie advised, would make them more acceptable...
I VOID WARRANTIES
Perhaps Magnepan advised sticking the M/T in front of the Bass panels so as to accommodate/attract customers having smaller than optimally sized listening rooms. Other than placing Bass panels so as to reinforce their response, it's all a matter of personal preference after having listened to them in a variety of locations/positions. Listening rooms all differ as well as does every listener's hearing acuity, which goes south in time. Given the exact same environment in which I once by 'padded' the IV-A ribbons, 20+ years later I need to come up with ways to increase their response (short of being fitted with a hearing aid, whatcha say - would you kindly repeat that speaking louder and more slowly?).
Once you take out the original XO, you can use a simple 1st order symmetrical XO and arrange the TIV or IVa in an equidistant arc which gives great imaging.that the 20.1 never managed (nor the stock T IVa)I agree entirely with your observations but the equidistant arc option makes the distance between the drivers a non-issue.
The Neo8 array does a better job on all counts than the 20.1 mids and does better than the ribbon below 4-5 khz. The mids can run 200hz and change up to 6khz with minimal dispersion issues and even left without a low pass filter to give you an on-axis single driver source going to over 10 khz.
Edits: 02/15/15
I began my audio adventure with the AR-3 (before there was an AR-3A). My next long time relationship was with the Tympani 1C, back when Maggies were marketed by the Audio Research Corporation. I (naturally) used ARC's tubed pre-amp SP-3-A-1, and amp(s) D76A and at the same time a 'fling' with SS, GAS' Ampzillas I and II. Then about 22 years ago I went out with and still listen to a Tympani IV-A with Bryston amps (7B STs and 4B SST) Magnepan's XO-1 or a Marchand XO (I prefer to using the former passive XO).
I've never needed to go elsewhere for my audio 'kicks'. Today at my advanced age my hearing couldn't possibly be good enough to even warrant doing so.
IAE, it all boils down to having 'fun' and enjoying the time we've been allotted. So 'screwy' or not, I wish you many years of listening pleasure.
Sincerely, Norman M.
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