Hello I wanted to ask if anyone could explain what the "switchable Air Mod" is that can be fitted to the MK series interface units?
Air Mod
Hello John65b, My MK-121C's have the C mod. Roy Esposito does repairs and upgrades to the MK series interface units. He works for "Sounds Like New". An upgrade he offers is called "switchable Air mod". I emailed Roy but didn't hear back from him so I thought I would ask the question here on the forum.
Hello John65b, My MK-121C's have the C mod. Roy Esposito does repairs and upgrades to the MK series interface units. He works for "Sounds Like New". An upgrade he offers is called "switchable Air mod". I emailed Roy but didn't hear back from him so I thought I would ask the question here on the forum.
A friend had Roy upgrade his interfaces, and also installed the air mod. My friend passed away shortly after getting them, so very little time was spend with them.
But if i remember right, part of the mod takes the adjustable high fre control gain knob out of play.
Hopefully Roy can fill us in with more detail.
But if i remember right, part of the mod takes the adjustable high fre control gain knob out of play.
Hopefully Roy can fill us in with more detail.
That's too bad, I bet your friend was excited to get the upgrades. Hopefully he was able to enjoy them while he had them. Did the speakers stay in the family or did someone buy them? Do you know which model Acoustat he owned? Roy finally acknowledged my email but was too busy to respond because I had several questions about the MK-121. Do you know if one of the upgrades includes removing the flimsy attached power cord and replacing it with a socket to fit standard IEC power cord?
My Buddy had the Model 4. He did very much enjoy the upgrades, he had them for about 4-5 weeks with the upgrades. He got them through a trade with another friend, and afterwards, they went back to the friend.
We did one more project before he passed, and that was we made him a pair a Super tweaters with a pair of Maggie 2.6 Ribbons coming in at around 10,000khz.
He had a smile from ear to ear. I really glad we got them up and running.
3 weeks later he was gone! :O(
RIP
Clay
We did one more project before he passed, and that was we made him a pair a Super tweaters with a pair of Maggie 2.6 Ribbons coming in at around 10,000khz.
He had a smile from ear to ear. I really glad we got them up and running.
3 weeks later he was gone! :O(
RIP
Clay
I have a pair of Model 3s and had the interfaces done by Roy. I'm not really an electronics guy, but the air mod switch does bypass the high frequency control and seems to add "air" and sparkle to the highs, but I couldn't tell you if any additional circuitry is involved. As far as I know, he doesn't offer an iec option, although he does install a new stock power cord as part of the service.
Hey Meat popsicle, Thanks for the info. Is the replacement power cord more substantial or longer then the stock power cord? Also what associated gear are you using to power your Acoustat III's with. Have you tried both SS and tube gear and which do you prefer?
So, the "air mod" bypasses the potentiometer element in the high freq circuit? I can understand that if someone prefers the sound with the pot turned "up" all the way which takes its resistance out of the circuit, then why have it there?
I have always wanted to remove the HF pot altogether (I always have it on min resistance anyway) and put that pot in series with the bass transformer and dial in best bass/midbass.
If anyone has ever seen the schematic to a Sound Labs (actually found it) they would understand why (they have up to 50ohm series resistance on bass tranny)
I know they have separate bass and treble panels unlike the "mixer" of the Acoustats, but wanted to try nontheless... with that kind of series DC resistance, you never have to worry about having an amp peter out on you...
If anyone has ever seen the schematic to a Sound Labs (actually found it) they would understand why (they have up to 50ohm series resistance on bass tranny)
I know they have separate bass and treble panels unlike the "mixer" of the Acoustats, but wanted to try nontheless... with that kind of series DC resistance, you never have to worry about having an amp peter out on you...
Attachments
The schematic you posted is for an early SL design that used separate bass and treble panels.
The 50 Ohm series resistance was not for dialing the amount bass you want, rather it defines the low-pass crossover point for the bass panel. The amount of bass was adjusted by selecting different primary taps. For lower distortion, it would be better to move the series resistance over to the secondary side like Acoustat does with their mixer resistors.
All SL designs since the 90s have used a mixer and drive the entire panel with the same signal just like Acoustat.
I know I have a representative schematic floating around somewhere...will see if I can locate it tonight.
Typical Soundlab Interface Circuit
Attached is a pic and schematic of a typical SL interface.
The circuit will vary slightly depending on the vintage and model.
Note that the circuit is extremely similar to the Acoustat MK-121C
The main difference is the Acoustat mixer resistors are replaced with a high resistance primary winding on the LF transformer.
More info comparing Acoustat and SL mixer here:
http://www.diyaudio.com/forums/plan...cls-ii-stators-best-way-do-2.html#post3822064
Bass level is adjusted by selecting different taps on the LF transformer.
Mid level is adjusted by selecting different inductance in series with LF transformer.
Highs are adjusted with variable resistance in series with HF transformer.
Attached is a pic and schematic of a typical SL interface.
The circuit will vary slightly depending on the vintage and model.
Note that the circuit is extremely similar to the Acoustat MK-121C
The main difference is the Acoustat mixer resistors are replaced with a high resistance primary winding on the LF transformer.
More info comparing Acoustat and SL mixer here:
http://www.diyaudio.com/forums/plan...cls-ii-stators-best-way-do-2.html#post3822064
Bass level is adjusted by selecting different taps on the LF transformer.
Mid level is adjusted by selecting different inductance in series with LF transformer.
Highs are adjusted with variable resistance in series with HF transformer.
Attachments
blgtrio, the new cord appears to be the same or slightly larger gauge as the original, and is roughly 6 ft (2 meters?) in length. I use a Benchmark DAC2L as my pre, and I was running an unrestored TNT-200 amp until recently, now a Parasound Halo A21. I have a Jolida JD 502 BRC in the LR on a set of Janszen Z900's but I've never considered it to be good enough to hook up and do a fair comparison to the SS amps.
Here are a couple of the items that went into my decision making process of choosing SS over tubes, and why I went with the Parasound in particular over the Acoustat TNT-200. Some may find this interesting reading, comments welcome.. Sanders Sound Systems - Tubes vs. Transistors White Paper and http://www.parasound.com/pdfs/JCinterview.pdf
Yeah I read that white paper. Mr Sanders is a great guy! I really liked his 10C and ESL amp I had.
His main point is use an amp ESLs that will never clip - thats why his ESL amp are like 900w@4ohm....
John Curl, Nelson Pass, Roger Sanders...all these guys ROCK! If these guys were absent from this hobby, I would have passed thru my DIY Audio phase years ago...all very helpful...and very patient too!!!
I am actually playing with a Parasound 2250 that sounds very nice on ESLs. It also has the impedance switch 2-4 ohm and 6-8 ohm which comes in kinda handy on ESL speakers.
His main point is use an amp ESLs that will never clip - thats why his ESL amp are like 900w@4ohm....
John Curl, Nelson Pass, Roger Sanders...all these guys ROCK! If these guys were absent from this hobby, I would have passed thru my DIY Audio phase years ago...all very helpful...and very patient too!!!
I am actually playing with a Parasound 2250 that sounds very nice on ESLs. It also has the impedance switch 2-4 ohm and 6-8 ohm which comes in kinda handy on ESL speakers.
Last edited:
Thanks for the info from JC.....
Vary fair guy...no BS...more people should read this..
the res. can... make or break the sound.....most think... well its good a nef...an hes talking about new res...must less 20 year old...hehe
But like Bob Carver i am a tube guy....but as For SS old Krell.....bias up right... with new caps....sounds best for me....Vary tube like...
Most just wont wire...are caps...are cabel lifters....good luck
Vary fair guy...no BS...more people should read this..
the res. can... make or break the sound.....most think... well its good a nef...an hes talking about new res...must less 20 year old...hehe
But like Bob Carver i am a tube guy....but as For SS old Krell.....bias up right... with new caps....sounds best for me....Vary tube like...
Most just wont wire...are caps...are cabel lifters....good luck
Last edited:
- Status
- Not open for further replies.