Blasphemy: I do not like the Tobin 104T Mods on my Bozaks

Hey man,

I can't say. I've looked through my N10102 images, I've searched google. Seeing what numbers are on the original board aren't legible enough.

Great news on the l-pad. Without it, the system just sounds dull as a bag of wet marbles. Not cool!

Biggles
 
The labels unfortunately vary by crossover.

The tap position is what ultimately matters.

Your symptoms had to be inductor taps that were incorrect, and it makes sense that both were off in the same physical direction.

Missing half of the midrange would certainly cause voices and instruments to vanish at the high end and be too loud (twice as loud as it should be) and very distorted at the low end.

As we discussed, I think the L-Pad setting turns out to be a matter of individual preference and room characteristics, and Tobin's one size fits all really fits none in practice.

Problem solved, enjoy the Bozaks!
 
Problem solved!

I have been listening them casually for a few hours - I like them again. I am using my old AudioControl EQ for fun - some records need it (Led Zeppelin I and II especially) to bobs the very top end, but I can actually listen to them again. I would like more tweeter, but given all the factors, I'll leave them be for now.
 
So, to all that have followed this thread so far, I'll sum it up:

The Tobin mod does work.

Using an L-pad to attenuate the tweeters is a better (more flexible) option than the 7.5 Ohm resister.

Setting the Woofer to the end of the inductor, (the lug marked N-101 on my crossovers) and the mid should be connected to the center tap of the inductor (the lug marked N-102 on my crossovers).

Retrovert's flower-pot midrange backer is a great addition while you are in there.

PAY ATTENTION TO DETAIL: make sure it is all correct before you judge.

I really hope this thread helps someone in the future - I spent over a year only to realize that I was not paying attention and that I never had clear instructions as to where to connect the woofer/mid inductors.
 
Problem solved!

Which is great news.

I have been listening them casually for a few hours - I like them again.

The rejiggered woofer-midrange crossover point makes a big difference in clarity, as does the flowerpot.

I am using my old AudioControl EQ for fun - some records need it (Led Zeppelin I and II especially) to bobs the very top end, but I can actually listen to them again. I would like more tweeter, but given all the factors, I'll leave them be for now.

BTW, the AudioControl manuals are available, and last year I convinced AudioControl to release the schematics to the old equipment so it could be rebuilt. An AK member here was gifted my AudioControl 11, so I can't readily answers about the internals on it. But I do have the owners manual and schematic if you need them...

I suggest you replace the tantalum capacitors with film as tantalum has higher distortion and DC bias issues. The RCA 4136 opamps used for the gyrators should be reasonably low noise for this application, but they are no longer made. If you want to upgrade them they will need to be replaced with BrownDog adapters for newer, and lower-noise, opamps.

An EQ is always a nice way to tweak the high-end response, and it likely has greater granularity than an L-Pad.
 
Last edited:
PAY ATTENTION TO DETAIL: make sure it is all correct before you judge.

True words for any audio project.

I really hope this thread helps someone in the future - I spent over a year only to realize that I was not paying attention and that I never had clear instructions as to where to connect the woofer/mid inductors.

I am certain your experience will prove useful to others. The doubled low-end of the midrange and its removed high-end certainly would account for your not liking the "upgrade". This easily-made mistake—the position of taps obviously varies whether one looks from the top or the bottom, and even by the wiring on the crossover itself—has likely been made by others who disliked the Tobin modifications, and will likely be again made in the future for similar reasons.

Sorry I didn't more rapidly identify the problem as miswired inductors. Once you stated you had to attenuate the midrange it was clear the woofer tap was off. And the misssing upper end of the midrange could only have come from one place.

If you were local I would have given a listen and probably could have saved some misery. Amtrack, alas, is a bit more involved then a handful of subway stops...

But it's all good now. Do let us know how you like them after listening for a few weeks as you become accustomed to uncolored sound.
 
Just an update for those interested, I have not been able to spend any critical listening time with them, but have used them in the background a few hours. They are much better, at times I quite like them. They need more tweeter - Retrovert is correct that I should move them to the top, but I'll probably not do it. I think I'll make some angled stands for them and see I that helps.
 
Hey Silicon,

Or just grab a slat of wood and toss it under the front and tilt them a bit. It's amazing how well that actually works. I found that the further decoupling you get from the floor, the more the bass suffers. Another mod you can do, is use maybe 3 washers on the lower portion of the mounting hardware on the tweeters. This will angle the tweeters up. I've tried this and it works a lot better than you'd think. I would imagine that opening them back up is the absolute, very least, the last thing you'd ever want to do, again. I say, tilt.

Biggles
 
I am thinking of leaving the factory tweeters in place an augmenting them with a folded ribbon on top with its own crossover - all be external, of course.
 
Hey man,

And that was going to be my next suggestion. I would suggest using external crossovers for the entire system. This way, you could use, or disconnect the original tweeters at your discretion. Or use both the originals up to maybe 8k, then add a super tweeter externally. But having the main crossover outside the box, it makes all these mods doable without having to open up your cabinet. Plus, it looks really cool and all technical.

Biggles
 
Well, it has been a couple weeks. I do not hate them, but I am not in love with them. I just ordered a tube amp to pair with my La Scalas so I can move the Mac 4100 to the Bozaks and try that combination. Will try the tube amp first, of course, just for fun.
 
Last edited:
Hey man,

Welp, you can't ask for more than that. Thankfully, the issues got straightened out so you at least got to hear them properly. Agreed, try them with all the amplification you have on hand. If it's not fun, not worth doing.

Biggles
 
I guess worse case scenario is that I run them with my graphic EQ (AudioControl The Octave) - not a bad thing.
 
I have no issues with using an eq, when needed. I run so many different pairs of speakers and amplifiers, not all are considered to be perfect in every way. Especially in my living room, some need a little kiss of this, and a little hug from that.

Biggles
 
What settings are you using with the EQ? Boosting the high end or the midrange? Unless you are a basshead, or attempting to cause earthquakes, boosting the low end of the B-199 is likely unnecessary, so I expect you're not doing that.

As I recall, and please correct me if I am mistaken, you are using a pair of the paper-cone B-209?

The paper cone delivers a slightly different sound and response than the aluminum cone B-209. Again, one should only use or purchase the B/Bc/C variants, never the A, which requires a special damping ring to reduce ringing issues and is consequently acoustically inferior to its successors, particularly after the ring has dried out or been removed.

The other issue is room treatment which can dramatically affect the sound one hears. This can vary with the height of the speaker, too. You have the Bozaks on stands? I saw you were discussing making some, but I don't know if you've done this. Raising them off the floor on legs will dramatically improve the sound.
 
Back
Top Bottom