Bridgeclone

[Peter Daniel]

What about Jensen JT-11P-1 http://www.comtran.com/datashts/11p1.pdf

It seems to be readily availabe.

 

[ThorstenL]

Koinichiwa,

What about Jensen JT-11P-1 http://www.comtran.com/datashts/11p1.pdf
It seems to be readily availabe.

From Jensen the JT-10KB seems a better solution:

http://www.comtran.com/datashts/10kbd.pdf

For this reduce the 10k input resistors to 5k to compensate the 4:1 stepdown ration instead of 2:1 as for the S&B TX-101. Of course, the Jensen has neither center tap nor dual secondaries, meaning you get a floating balanced drive signal. This has implcations for the offset and the resistance on the non-inverting input and may require changes to the circuit.

Instead of randomly stabbing at a part number and asking "will this work", how about you look at the TX-101 datasheet (or what passes for one anyway) and then look at other manufacturers comparable products? Saves time.

Sayonara

 

[Peter Daniel]

Instead of randomly stabbing at a part number and asking "will this work", how about you look at the TX-101 datasheet (or what passes for one anyway) and then look at other manufacturers comparable products? Saves time.

I would've done it long ago, if I knew where to look. Any links to their site (S&B)? I have no experience regarding transformers whatsoever.

 

[ThorstenL]

I would've done it long ago, if I knew where to look. Any links to their site (S&B)? I have no experience regarding transformers whatsoever.

http://www.stevens-billington.co.uk/pagehifi.htm

Especially interresting is:

http://www.stevens-billington.co.uk/page102.htm

 

[Mats J]

Okay, call me dim, a buffoon, or what have you (trust me, if you can think of an insult, I've been called it). Why would doing this circuit :

http://www.diyaudio.com/forums/attachment.php?s=&postid=161559

but substituting the left hand side from this page for IC1a/b:

http://www.jensen-transformers.com/as/as060.pdf

be suboptimal? What am I missing?

tia-
Mats

 

[carlmart]

Why would doing this circuit be suboptimal? What am I missing?

Who says that substitution, a transfomer for an IC, would be suboptimal?

Please read here:

http://www.diyvideo.com/forums/showthread.php?postid=161763#post161763

You will see that the reason I was looking for a way to stay away from transformers was for the project not to be expensive or limited to specific and hard to get parts (input transformers).

As I carry on several tests, I will tell on eventual differences on the several ways for this project.



Carlos

 

[ErikdeBest]

About the last developments

Ola Carlmart

Have you already built a prototype of your idea? Is it working fine?

How about disponibility of components for a bridgeclone in Brazil?

Boa sorte

 

[leadbelly]

I know this thread has died off, but I was wondering if anyone could explain what to look for in a suitable transformer.

The idea I had in mind was that the xfo + 2 x 3875's would be a great sub amp, and since the band of freq is smaller, less subceptible to poor xfo quality.

Would these do the trick:

15KCT:15KCT

Inexpensive, and easily available.

 

[ThorstenL]

Koiniciwa,

I know this thread has died off, but I was wondering if anyone could explain what to look for in a suitable transformer.

The idea I had in mind was that the xfo + 2 x 3875's would be a great sub amp, and since the band of freq is smaller, less subceptible to poor xfo quality.

Would these do the trick:

15KCT:15KCT

Inexpensive, and easily available.

Well, most "inexpensive" transformers suffer especially at the frequency extremes. So for a sub-amp you are probably better off using a cheap chip. The closer you get to DC the better cheap Op-Amp's become. Below a few 100Hz they can be quite good.

Horses for courses, for a subwoofer I'd suggest the dual Op-Amp circuit I suggested to Carlos (further up in the thread) as better choice, using an NE5532 will be just fine that far down.

Sayonara

PS, always consider parallel/bridged, better thermal handling and more peak current capability, both count in subs.

 

[leadbelly]

Thanks,

And after researching it a bit more, I can see that the economics are not great either, as the lm6181 is $C5 and that cheapo xfo was $C6. Just doesn't make sense at all, really.

So, you were suggesting a preference for the lm6182, would you therefore think using twice as many of the still available lm6181's would work better than lm6172's?

 

[ThorstenL]

Koinichiwa,

Thanks,

And after researching it a bit more, I can see that the economics are not great either, as the lm6181 is $C5 and that cheapo xfo was $C6. Just doesn't make sense at all, really.

So, you were suggesting a preference for the lm6182, would you therefore think using twice as many of the still available lm6181's would work better than lm6172's?

I am actually suggesting that used in a subwoofer filter, there is little to choose between the much maligned NE5532, TL07X/08X or any other Op-Amp. I mean don't dig the 741 out of retirement, but for such low frequencies the PSU becomes much more more important than the chip. Chip's make large difference at higher frequencies, but not so much in subwoofers.

Sayonara

 

[Terry Demol]

Koinichiwa,



They would sort of work, but are really by far too low impedance to work well in a lineinput. The LL7901/7902 is what you'd be better looking at, if it has to be lundahl.

Sayonara

KYW,

I am using LL7902 for mic pre's currently and they are
switchable in/out specifically for their coloration. They do
have some DDR degradation and they also flatten
dynamics somewhat.
I think the S & B or Jensen would be better option
if transparency is the goal.

T

 

[leadbelly]

I checked a bit and it looks like the only 0.1% resistors easily available in small quantities are 1/16 watt. Would these work as feedback resistors or are they too small?

 

[leadbelly]

OK, well if nobody likes that question, let me ask a more basic one for my knowledge: why 0.1%?

Is that a tolerance spec for the actual construction, so that the constructor must match resistance values within that range and so it is meant as a spec for mass production? (in which case matching pairs of 1% resistors would be acceptable)

Or is it a manufacturing tolerance dictating that product tolerance must be met in order to guarantee properties other than resistance, such as impedance or stability over a long lifespan? (in which case 0.1% resistors must be used)

 

[ThorstenL]

Koinichiwa,

OK, well if nobody likes that question, let me ask a more basic one for my knowledge: why 0.1%?

Is that a tolerance spec for the actual construction, so that the constructor must match resistance values within that range and so it is meant as a spec for mass production? (in which case matching pairs of 1% resistors would be acceptable)

Or is it a manufacturing tolerance dictating that product tolerance must be met in order to guarantee properties other than resistance, such as impedance or stability over a long lifespan? (in which case 0.1% resistors must be used)

Well, the 0.1% Spec is given as 0.1% Resistors are readily available from any decent electronic part supplier (Mouser & Digikey certainly should do them in the US, in Europe Radio Spares or Farnell).

Ideally all resistors should be zero tolerance, but the tighter toleranced resistors get the more expensive they get and the harder to find are they. And yes, you could hand select if you like.

Sayonara

 

[leadbelly]

Thanks!

It was Digikey that I was hoping to order from, as the whole digikey.ca thing makes it so easy. But they only have 0.1% SMD 1/16W in small quantities. Mouser however does stock 0.1% leaded resistors.

 

[cybervagrant]

I've looked into this BPA. Here's my two cents.

Use the servos unless you are a miser or a sloth. I talked with an engineer at Nationals audio division about this. The servos will keep the noise level and extraneous current flowing between the devices much lower. That means it will better and louder, if you do.

 

[tbla]

i use the servos....

 

[carlmart]

Use the servos unless you are a miser or a sloth. I talked with an engineer at Nationals audio division about this. The servos will keep the noise level and extraneous current flowing between the devices much lower. That means it will better and louder, if you do.

Aren't you being a bit fast in lining up with what a Nationals engineer may say?

First of all, I haven't much against servos or have had so much practice with them, but many people whose ears I trust say they can be "heard". That is they introduce behaviours that do not belong in a "clean" sound, that is they do not improve the sound or add nonlinearities that shouldn't be there.

Second, National suggests a parallel/bridging arrangement that some find not ideal, using inverting and non-inverting blocks. When I named this thread "Bridgeclone", the idea was to do something using the inverting circuit as the basic brick to work from.

So perhaps your suggestion would belong on a new thread, which I would happily follow as I am a flexible DIYer who does not believe in stone cut recipes.



Carlos

 

[vic2]

I have reread the app note from National. It specifically says that if .1% tolerance resistors are used, then the servos can be avoided.

The .1% resistors are apparently there to keep current from flowing through the other opamp circuits. Could this be avoided by increasing the output resistances of the individual circuits thereby allowing on to get away lower tolerance resistors?

Vic