TX102 OCC copper version review

John Chapman · « **on:** 2 Sep 2003, 01:52 am »

Hello!

No I am not going to review my own stuff here! That would be kind of sad...

Just wanted to post that the latest issue of HiFi World has a review of the TX102 OCC copper version. I have read the review and will post it as soon as the next issue hits the streets (and once we clear it with Hifi World!). The contents of the issue can be found here:

http://www.hi-fiworld.co.uk/hfw/currentish.html

Many Thansk!

John Chapman
www.bentaudio.com

gonefishin · « **Reply #1 on:** 2 Sep 2003, 02:17 pm »

Hello John...thanks for letting us know about the review. I'll have to see if Barnes&Nobles has that magazine. (if not...could you e-mail me a copy before next month? as long as you get permission...of course)

I must say that I'm really interested in your tx102 pre. Right now...I'm considering two preamps. The Purist and your NOH.

After doing some reading and talking with others, both units seem to be very good performers...with most of the decision coming down to preference and system/room matching. There is one problem, which I'm sure your aware...is that it is almost impossible to find a unit near where you live...let alone talk someone into loaning it to ya. Do you offer any type of Demo unit for an in home audition (or something)?

I've also read some info leading me to believe, that in a few instances the tx102 may not match up well with the amplifier used in a system...I do understand that this situation is not all that common...but I would like to know more about this...before I may choose to buy.

My system can be seen thru the link below...located in my signature. At this time I've got some Cary 300B (with 6sl7 drivers) driving the "tops" of my speakers...and IRD mb100's driving the woofers. My plans are to upgrade the preamp...then build a new tube amp for the "tops". The amps I will most likely build will be a DRD type design (designed by someone else) that uses a 300B as the output, a 10y as the driver...and a 6sn7 as the input. My source will remain to be the Philips sacd1000...this will remain to be the sole source (for music) for some time...until a get me a TT. My system is integrated with my HT system. Now, I'm using a HT by-pass switch on my Joule-Electra pre. If there are no complications, I have no problem with simply using an input on the NOH...then turning the volume to "max"...allowing my pre/pro to be in control of all volume but allowing the signal to be passed thru to my 2 channel amps. My main concern is certainly music and 2 channel...but I do need to have an HT function.

thanks!
Dan

John Chapman · « **Reply #2 on:** 2 Sep 2003, 02:35 pm »

Gonefishin,

Thanks for the post! e-mail me about the article if you can not find it.

I just parked the last of the units I had on tour. I sent out 3 units on tour with good intentions even though many folks told me I was crazy. To make a long story short - I was crazy. It was a dissapointment that I could not keep it going but I do this for fun (full time and then some - but for fun!). Keeping the tour units organized and moving along was not fun- at all. One time a unit shower up with the lid right off and stuffed with packing peanuts. Another unit spent 5 months at one stop - rather than the 1 week demo period I was shooting for. I'd best not go on! I know it is tough to decide and demo's are best but with the low margin's I run I just can't afford the tour units. I do not want to raise pricing to cover that and I would have to.

Your system seems like it should fit fine with a TX102. The occational times a tx102 does not fit is with VERY high output impedance sources (rare) and very low amplifier input inpedance values (although this is less of a problem than folks might think). The other issue is getting enough gain but here again it is rare to have trouble - most systems have more than enough gain to run passive and if needed we can use the +6db gain mode.

Your system has a solid state source that will have a low output impedance and the tube amps will be highish impedance. The IRD is 22K input impedance so the net imp load the tx102 would see will still be fine.

Many Thanks!

John Chapman
www.bentaudio.com

gonefishin · « **Reply #3 on:** 2 Sep 2003, 02:42 pm »

Thanks for the reply

I can certainly understand your points about sending the units out.

Could you explain the 6db gain hook up? Is this a feature that can be switchable with the 0 gain? If so...can this be done with little detriment to the sound or performance with 0 gain?

Thanks,
Dan

John Chapman · « **Reply #4 on:** 2 Sep 2003, 02:49 pm »

Hello!

All TX102's ship ready to be run unity gain or +6db gain. It can be easily switched but I am a nut for keeping the signal path as clean as possible and so I don't recomend putting it in as a 'just in case' kinda thing - since it is rarely needed. If you think you'll have the need for it we can work out the best way to handle it. When you use +6db mode the TX102's becomes a harder load for the source to drive and so it's not a 'free lunch'. For a source like your player this is not a concern as it would be fine driving the unit either way.

Many Thansk!

John Chapman
www.bentaudio.com

gonefishin · « **Reply #5 on:** 2 Sep 2003, 03:36 pm »

ok...one last question...then I'll try not to pester you for a while

Do you have any cost effective ways of attenuating one of the outputs from the preamp...to the amp. This attenuation is need to level match the output from my speakers between the two amps (the mid/tweets are using first order crossovers...I have been trying a few things out...but, right now...these are going to stay) I currently have the outputs from the preamp split, and going to each of my amps...the output going to the tube amp has a Creek passive unit on there...until I figure out what I'm going to do.

If I do end up going with the NOH pre...what do you suggest would be best to attenuate the signal going to the mid/tweets? An in-line attenuator? or maybe after finding the value just use a resistive pad...as a set value?

thanks...ok....I'll try to give you a break now.

again...thanks!

John Chapman · « **Reply #6 on:** 2 Sep 2003, 05:25 pm »

Hello!

No problem with the questions - they are all great questions for the forum!

I have been lucky that when I bi-amp (which I do quite often) that I have had to pad down the low pass and that keeps the path to the more critical mid/high amp cleaner. You can pad down with a creek or just a pot or a pair of resistors once you know the value but in all these cases you loose much of the benifit of the transformer by introducing a significant series resistance between the TX102 and the amp.

This is a strange suggestion from a passive pre-amp guy but what I would do is use an active pre-amp in-line to the bass amp to boost the output to than amp - rather than pad down the signal line to the tube amp. If you bi-amp and use an electronic crossover (something to considder) in the bass section then choose a unit with a level control and with some gain to do essentially the same thing. Most electronic crossovers would have both gain and a way to set levels. This seems strange but it can work well and I think it is preferable to messing up the signal path to the high pass amp.

Post a bit more about crossover frequencies and crossover types you use and we'll work out a plan.

Many Thanks!

John Chapman
www.bentaudio.com

gonefishin · « **Reply #7 on:** 2 Sep 2003, 07:41 pm »

Quote

Post a bit more about crossover frequencies and crossover types you use and we'll work out a plan.

Many Thanks!

John Chapman

The Tad woofers are using a second order crossed at 800Hz* right now The 2441/EdgarHorn midrange comes in at 800Hz* using a first order crossover...from there...the 2441/horn combo has a nice natural drop-off at 10kHz...which is where the Fane tweeter comes in using a first order also.

*I do plan to try a 600Hz cross-over point at some time*

So far...I haven't tried any active cross-overs with my new speakers...I've only tried the existing first, first, second...and a set of line-level passives (which I didn't care for...although I will give it another try before I give up on them)

I'm not sure how much I have the tube amps "turned down" with my current set up/amps...I think it's about 10db. I do plan on getting another amp to drive my woofers...but that is certainly going to have to wait. (that dang money tree hasn't sprouted yet

)

thank ya

John Chapman · « **Reply #8 on:** 2 Sep 2003, 09:18 pm »

Hello!

I have some TAD 1601 drivers here and really like them. I also really like Edgarhorns - must be a really great system you have! To stay passive on the crossover I would get a used active pre-amp for the bass section. Then pump up the bass level 10db (or to suit). This would keep the high pass signal path clean. If you are into DIY there are lots of active pre-amp circuits that might be fun to put ahead of the bass amp to get the gain and do it for very little $. Start with a pot and then just put in a resistor divider network ahead of the active stage once you pick a level.

Thansk!

John

gonefishin · « **Reply #9 on:** 2 Sep 2003, 09:31 pm »

Huh...use an active on the bass to add X amount of gain to match up with the tube amps running wide open on the midrange...This idea makes me feel so much better! I like it!!! I really hated the fact that I had to pad down the midrange/treble.

What are you using the TAD's in?

thank you!!!!!!!!!!

John Chapman · « **Reply #10 on:** 2 Sep 2003, 09:56 pm »

Hello!

The TAD's are in vented enclosures. One of my earlier and more extreme boxes - 500 lbs per side nested boxes with 2" of sand all around and a 3" thich front baffle. Crazy and a pain to move around. I did not do that again!

I use my deep throat (named by Dan at Bottlehead... who else!) 140 Hz round tractrix horns with REPS drivers on top.

Always had the urge to try some TADS's in wodden round tractix horns from Bruce Edgar but never got to that project yet....

Thansk!

John

gonefishin · « **Reply #11 on:** 6 Sep 2003, 02:25 am »

Hmmm...deep throat...if he comes up with a couple more names like that...I may start thinking he has a fixation about something

I did look at the Barnes & Nobles...they do not have the mag. If you could get me a copy sometime, I'd appreciate it.

Well, here's what I'm thinking...If I get the NOH pre...I could hook it up to my tube amp to drive the midhorn and tweeters, with an unmolested signal...so to speak. Then, I can use the second rca out to go to a Foreplay that feeds the mb100 SS amps...I'll dial the 19db of gain on the foreplay down to match the output of my mid/tweets. The 19db of gain is actually a bit more than I would want...but hey, the foreplay is the right price...and is ready to be put together.

Whatcha think...do you foresee any problems or conflicts with this?

thanks again

John Chapman · « **Reply #12 on:** 6 Sep 2003, 03:50 am »

Hello!

Dan does have a theme going with the product names - lots of fun though!

The foreplay should be fine for that - esp if you have one around waiting to be built! It has lots of gain so that will be no problem at all.

Thanks!

John Chapman
www.bentaudio.com

gonefishin · « **Reply #13 on:** 7 Sep 2003, 08:06 pm »

John,

I notice that the NOH has a remote option. If I decide not to get the remote right away...I'm sure it would be fine to add it at a later date (when i get more money

)...BUT...is there anything to keep in mind, if someone plans to add the remote later? Maybe how you route the wires...length of wires...or something like that.

Thanks

John Chapman · « **Reply #14 on:** 7 Sep 2003, 09:36 pm »

Hello!

The Model TX102 and TX102S kits had a remote option too but it was added long after the case was designed so it was kinda patched in and not too easy to install. The NOH case was desinged with the remote in mind and it can be added easily later. No wires need to be moved and the switch stays mounted where it is without the remote so you don't need to plan for it when building.

Many Thanks!

John Chapman
www.bentaudio.com

ABEX · « **Reply #15 on:** 8 Sep 2003, 04:42 am »

Hello:
I have been intrested in OCC Copper and would like to know what differences you have found with it in comparision to regular OFC Copper. It has always been my contention that the grades of copper are important and that the interaction between insulators should be made also.

Often you see people alluding to the Dielectric constants where Teflon being best,besides air of course,but no one as yet can explain how sound might be changed by the use of certain insulators.

I have been experimenting with a different insulator materials at the moment that I shall be using in new designs I am marketing with better than satisfactory results.

Another thing I tried was, I had a cable made with the same type of insulator as what is used in 47 Labs OTA,but the sound is different even though thay are the same. Seems the Copper used might be of better quality than the OTA. I wonder also if it might be the way the copper is drawn or if the processes are different that accounts for the chamge in sound. People prefer my version it seems from the field testing I have done.

One of the things I recently read was the reason why Ven Den Hul started his own Co..When younger he noticed that when using 2 wires that were identical in specs sounded different in coils of cartridges.When he went to ask his authority why this was he could not get a definitive answer.

I have found that I have some good Silver IC designs that are cost effective that I can sell for substantially under $100 which is one of the reasons I have decided to start my own cable biz.

Anyways,what are your impressions of the different coppers? What makes the OCC standout over the OFC if you can say?

I hope I am not off base here and you are using OCC Copper in the BENT models.

Good Luck and TIA!

John Chapman · « **Reply #16 on:** 8 Sep 2003, 12:51 pm »

Hello!

The wiring inside Bent Audio TX102's has been OCC copper from neotech:

http://www.neotech.com.tw/occ.htm

The OCC is a process to minimize the grain structure in the wire and also to get the purity of the wire up to a decent level. From the little I knoww of it OFC (Oxygen free copper) is typically a putrity designation without reference to the crystal structure inside the wire.

We changed from standard grade copper magnet wire about a year ago in an effort to tweak the performance of the TX102 a bit. I have not compared enough different systems to make extensive comments but I feel that it pays to use decent quality wire and the neotech was the best I could find. We never did the in-between step of using OFC copper inside the TX102 windings. There are quite a few options for regular insulated wire but finding premium quality magnet wire (like that used for transformer winding) limits you too only a small number of sources - all with rather large min qty orders! This limits the number of different wires we could afford to test so I just went with the best quality I could find and called it a day.

Please let me know how you make out with your wire testing and what wires you discover to have what qualities.

Many Thanks!

John Chapman
www.bentaudio.com