Mastering Lab crossovers - worth it?

Thermionics

Post Whore In Training
I'm seriously considering building out a set of Big Red cabinets for my 604E drivers (I have the measurements so I'm not worried about being able to build them, other than my general incompetence with woodworking). I figure I can get by with the current subwoofer I'm using to augment the lower octave(s) so I don't need to have the 9 cubic foot cabinets, plus my wife does not want a gigantic pair of monkey coffins in the house.

The question I have for the gallery (@mhardy6647 - I'm looking at you since I believe you have a set) - are the Mastering Lab crossovers worth it / necessary to get the most out of the 604E in the Big Red cabinets? I realize that they are a significant upgrade over the standard N1500 crossovers that came from the Altec factory.

Thanks in advance.
 

John Frum

Secret Society Member
I’ve never seen any schematics published for the Mastering Labs crossovers. Just sayin’.
 

mhardy6647

Señor Member
I’ve never seen any schematics published for the Mastering Labs crossovers. Just sayin’.
You haven't looked very hard ;)


1595277289091.png

there's this too, FWIW...

http://www.audioheritage.org/vbulletin/attachment.php?attachmentid=46901&d=1280933585
(which downloads a PDF file -- in full disclosure)



Are they worth it? I dunno -- they're better than the stock Altec XOs in the sense that they reduce the stridency that some folks complain about. I am not the best person to ask because my "Altecs" have mutated substantially (perhaps hideously*) in the past couple of years. These things do happen... :smoke

______________
* ein ungeheures Ungeziefer, as it were. ;)

1595277681352.png
 
Last edited:

Thermionics

Post Whore In Training
You haven't looked very hard ;)


View attachment 25718

there's this too, FWIW...

http://www.audioheritage.org/vbulletin/attachment.php?attachmentid=46901&d=1280933585
(which downloads a PDF file -- in full disclosure)



Are they worth it? I dunno -- they're better than the stock Altec XOs in the sense that they reduce the stridency that some folks complain about. I am not the best person to ask because my "Altecs" have mutated substantially (perhaps hideously*) in the past couple of years. These things do happen... :smoke

______________
* ein ungeheures Ungeziefer, as it were. ;)

View attachment 25719
Are you using yours with your "mutants", or are you using JELabs crossovers?

(oh, and props for the Kafka reference)
 

je2a3

Senior Member
All that complexity probably took care of the raggedness resulting from the "woofer trying to play too high and horn playing too low" at the expense of efficiency. Those inductors + the 5.5uf/25 ohm Zobel network across the woofer terminals sap power. But it'll still be a relatively easy load for classic PP tube amps but not so sure about flea power DHT amps, like an SE2A3. If memory still serves me right, I read about Doug Sax using behemoth tube amps to drive his ML 604s.
 

Thermionics

Post Whore In Training
All that complexity probably took care of the raggedness resulting from the "woofer trying to play too high and horn playing too low" at the expense of efficiency. Those inductors + the 5.5uf/25 ohm Zobel network across the woofer terminals sap power. But it'll still be a relatively easy load for classic PP tube amps but not so sure about flea power DHT amps, like an SE2A3. If memory still serves me right, I read about Doug Sax using behemoth tube amps to drive his ML 604s.
Well, I'm driving with a PP 7591 amp (Fisher 660A) good for an optimistic 32WPC.
 

je2a3

Senior Member
Well, I'm driving with a PP 7591 amp (Fisher 660A) good for an optimistic 32WPC.

I never built an all-out ML XO but used my 605B with a Zobel. I liked it enough to have uploaded it. But shortly before moving back to the US, I removed the Zobel network from the N1600 because even with an SE300B, I was missing micro/macro dynamics, a compromise I didn't quite like in the long term. Since my 605B was left in the attic, I couldn't continue/follow up on that experiment.

I was just sharing my experience playing around with crossovers and flea power amps in my previous post. I wasn't trying to discourage anyone from building the ML XO because it is an honest and successful attempt to blend the woofer and horn in the Altec Duplex system.
 

Thermionics

Post Whore In Training
From what I understand (3rd or 4th hand, mind you), the Mastering Lab crossovers are supposed to be handy in taming the 3kHz hump that the Altec duplexes seem prone to exhibiting.
 

Thermionics

Post Whore In Training
I never built an all-out ML XO but used my 605B with a Zobel. I liked it enough to have uploaded it. But shortly before moving back to the US, I removed the Zobel network from the N1600 because even with an SE300B, I was missing micro/macro dynamics, a compromise I didn't quite like in the long term. Since my 605B was left in the attic, I couldn't continue/follow up on that experiment.

I was just sharing my experience playing around with crossovers and flea power amps in my previous post. I wasn't trying to discourage anyone from building the ML XO because it is an honest and successful attempt to blend the woofer and horn in the Altec Duplex system.
I'm looking to try and buy an original if I can find one for a decent price. Just want to make sure it is worth the money.
 
All that complexity probably took care of the raggedness resulting from the "woofer trying to play too high and horn playing too low" at the expense of efficiency. Those inductors + the 5.5uf/25 ohm Zobel network across the woofer terminals sap power. But it'll still be a relatively easy load for classic PP tube amps but not so sure about flea power DHT amps, like an SE2A3. If memory still serves me right, I read about Doug Sax using behemoth tube amps to drive his ML 604s.

“Raggedness” is a good description of what I heard when I had GPA 604H drivers with the GPA crossover. Once identified, it was impossible to ignore.
 

Thermionics

Post Whore In Training
All that complexity probably took care of the raggedness resulting from the "woofer trying to play too high and horn playing too low" at the expense of efficiency. Those inductors + the 5.5uf/25 ohm Zobel network across the woofer terminals sap power. But it'll still be a relatively easy load for classic PP tube amps but not so sure about flea power DHT amps, like an SE2A3. If memory still serves me right, I read about Doug Sax using behemoth tube amps to drive his ML 604s.

“Raggedness” is a good description of what I heard when I had GPA 604H drivers with the GPA crossover. Once identified, it was impossible to ignore.
So it sounds like (provided I have sufficient grunt to drive the speakers) the Mastering Lab crossover might be a good investment for these 604E drivers (which I love, BTW), especially if I'm building Bid Red Monitor cabinets.
 

Audionut

Next Round Is On Me
So it sounds like (provided I have sufficient grunt to drive the speakers) the Mastering Lab crossover might be a good investment for these 604E drivers (which I love, BTW), especially if I'm building Bid Red Monitor cabinets.
Had I not know a master crossover builder in @marantzfan , I’d be hunting down a set of ML crossovers for my 604’s..oh and I’ve definitely thought about a big red build. Looking forward to seeing where this takes you.
 
Last edited:
I’m a little late to the thread.

I've owned 604Cs for 44 years. I put them in properly sized and damped cabinets 26 years ago. I added Mastering Lab crossovers 18 years ago (I was lucky to find a NM pair with close serial #s for only $600). But there was little improvement. In fact, sounded worse in some way, it muddied the sound. So I had the caps upgraded to Jensen foil oil caps.

Big huge difference!

The MLCs smooth out the brittleness at/around 1800. If you get the MLCs, assume the caps have dried out and replace them.
 

Audionut

Next Round Is On Me
I’m a little late to the thread.

I've owned 604Cs for 44 years. I put them in properly sized and damped cabinets 26 years ago. I added Mastering Lab crossovers 18 years ago (I was lucky to find a NM pair with close serial #s for only $600). But there was little improvement. In fact, sounded worse in some way, it muddied the sound. So I had the caps upgraded to Jensen foil oil caps.

Big huge difference!

The MLCs smooth out the brittleness at/around 1800. If you get the MLCs, assume the caps have dried out and replace them.
Welcome to the haven! Please stop by the member introduction thread and share a little more about you/your system. System pictures are greatly appreciated too!:)
 
Top