Pass B1

[rikhav]

When I used 221ohms in all recommended positions,I found thin sound with less bass.Sound was lively.But found that actual sound in recording was little different.
When I used all 1K,Bass was there,but no attack.Also lot of detailing missed which was there in 221 ohms X 4 mod.So started to find the midway solution and probably better one.I found that output resistor is actually changing sound signature and not the other two.So I tried different combinations and found this as balanced.

Thanks for the detailed explanation
Maybe some people can try out the mod you suggested and give some feedback

In my setup there is a very evident increase in bass, details and resolution through out

So does that means its ultimately upon system matching?

With some amps 4 x 221 ohm will work and with some what you have suggested

 

[spirovious]

Yes.Depending on speakers, sound will change.With this mod,mid bass improved too.Some will find that soundstage narrowed,but l feel its a complete signature.As said earlier,its a midway to achieve a balance.

 

[TheCoolestOne]

Today I had the opportunity to check out the Mod done by Spirovious on his B1 when he and FM Darshan Joshi came over. We has a 4 hr listening session.

We compared my B1 with the 221 ohm mod suggested by Om and others with Spiro's B1 and his mod of 306 ohms. Both Spiro and Darshan are very familiar with my setup so the difference was noticed in seconds when we connected Spiro's B1 to the chain, especially the bass which sounded much more improved than mine.

In my earlier post I had mentioned that the 221 ohms mod improved detailing and the soundstage on my B1 but there something lacking/missing in the Bass.

Spiro's B1 sounds balanced - more fuller and complete. It has the characteristic open, dark and clean sound that the B1 is associated with, but with an added advantage of a nice tight , enhanced bass and rounded treble while maintaining a wide sound stage.

Others should try this simple mod and share their views. The cost factor involved is negligible but the satisfaction is priceless. I for sure plan to mod mine at the earliest. We plan to try a 350 ohm mod next instead of the 306 ohm, time permitting. Will post our updates when done.

After reading about B1 mods,I tried myself.I got a modified kit from Sachin which included 221 ohms resistors and not 1K.When I finished B1,I felt that sound was very open,but some what thin.Bass was less.So I tried 1 k resistors and heard the original B1 sound.Yes bass improved and sound was lifeless or with less details.So I just followed the circuit path and found that output resistors(104 and 204)are the only which are making difference.Not other two suggested in the mod.So kept 102,202 as it is(1K) and used two 221ohm resistors in series.So effective resistance at 104 and 204 is now around 442ohms.Why around 442,I did not remove earlier 1K and its parallel to 442ohms.
Now I feel the overall sound is complete.Good Bass and certainly detailed sound.In my opinion,it outputs the original sound present in the recording.I thing this mod is midway to original B1 and modded by experts.
So its as followed-

102,202 = 1K
104,204 = 442 ohms.(if 1K in parellel,its 306.5ohms as final)

One must try and post their views.

 

[spirovious]

It was a really nice time spending with you.I was eager to know how my findings reflect on others set up and today got the chance.When a different set up too have some good outcomes,we can say that the mod is working in correct way.

Yes,the sound was very natural with correct amount of Bass and silk treble. Vocals were perfect.We also had a quick change with 265ohm resistance,but it spoiled the balanced.So we listened with 306ohm and compared with other options.Instruments could be felt and effect was a live sound.I must say it was a musical day today.

Set up used used was=
Sony BDp/Toshiba BDp > Subbu DAC> modded B1> Rotel power amp> Wharfedale 9.2

 

[darshanjoshi]

What an experience over all.

Could not belive that small changes in resistors could make so much of a difference.
Spiro has done a good job in coming up with this mod.

I guees spiro spotted that B1 was not doing good job when he had connected headphones directly to the DAC and found DAC sounds much better without B1 in the chain.

With the modded B1 sounded became much livlier, full bodied with darker background.
Maybe it was more of system matching but still superb SQ overall.

We are tried Norge 2060 but it was not upto the mark. However adding B1 in the chain, SQ became much better.

 

[spirovious]

Maybe it was more of system matching but still superb SQ overall.

May be,but it matched with 2 systems.Definitely one can give a try.The Mod is very cheap and one looses nothing much in experimenting.If it doesn't work,change the resistor value till you get the perfect balance in your system.

 

[rikhav]

May be,but it matched with 2 systems.Definitely one can give a try.The Mod is very cheap and one looses nothing much in experimenting.If it doesn't work,change the resistor value till you get the perfect balance in your system.

Surely its a case of proper system matching but hats off to you for thinking out of the box

In my case with 221 ohm resistors at all 4 points has improved bass and body in the sound by quiet a margin

Will surely like to try the Spiro mod

 

[keith_correa]

Can't one use a potentiometer and then determine what value works best? That will eliminate the need to swap resistors while experimenting.

 

[gobble]

I think what's happening here is a form of active BSC in the preamp. Therefore with different speakers and different compensation circuits in them, people are experiencing different SQ.
G0bble

 

[omishra]

Set up used used was=
Sony BDp/Toshiba BDp > Subbu DAC> modded B1> Rotel power amp> Wharfedale 9.2

Thanks for sharing this. IMO you have WF9.2 speakers, which I think more bass heavy. So finding may differ.

 

[spirovious]

Thanks for sharing this. IMO you have WF9.2 speakers, which I think more bass heavy. So finding may differ.

Yes,but in that case 220ohm resister should have been enough.in fact bass was very less with bass heavy speakers,that surprised me.So changed the resistor value to higher.

 

[jls001]

With nothing better to do on a Sunday evening, Rikhav and me monkeyed around with the Spiro mod at my place.

In my setup, there is a definite change. Most noticeable is the bass weight, which went up a notch.

I think the mids recessed a bit with the mod, and this led to vocals to be pushed back in the mix, and gave a sense of deeper soundstage than before.

The highs were airier.

We did many rounds of (sighted, btw) A/B of all 220 Ohms v/s

R102, R202 = 1K
R104, R204 = 306 ohms.

The Spiro Mod (TM of Spiro) sounded better to me in my setup, though the changes were mostly subtle, except for the fairly obvious improved bass weight and texture.

I hope Rikhav will write his impression and preference in my setup as well as his when he has some time to give it a listen.

 

[TheCoolestOne]

In my setup, there is a definite change. Most noticeable is the bass weight, which went up a notch.

Yes this was the most noticeable change in my setup with spiro's mod. Wharf 9.2 being base heavy we were expecting spiro's mod might create an overwhelming base as compared to the 220 mod but surprisingly the base sounded good.

With the 220 ohm mod and base heavy speakers one would expect sufficient heaviness in the base but it was not so.

The original 1k gave a heavy base in my setup but with a smaller sound stage and recessed vocals and mids. With the 306 mod the system sounds more open and better balanced but still a little scope for improvement in the low frequencies therefore time permitting we are looking forward to a mod near abouts 350 ohms.

 

[spirovious]

The Spiro Mod (TM of Spiro) sounded better to me in my setup, though the changes were mostly subtle, except for the fairly obvious improved bass weight and texture.
.

Nice to know that the sound improved a bit.Also different speakers can sound different way.So may everyone not improve vast improvement.Whenever I test a device,I try to listen it with my ATH-M50 headphones.It picks up minor changes too which are easily missed in speaker systems due to many reasons.I am sure that in acoustically corrected room and flat sounding speaker system,one can make out the changes easily.Using 350ohm resister,bass can be improved,may be heavy.A simple way is that instead of 1K resistor in parellal to 440ohms,add another 1k in series (to 1k)and make so that 2K will be parallel with 440ohms.It will make total resistance of 362ohms.That will increase the bass,but may sound stage will shrink and also treble may not be better.Not tried yet though.

 

[omishra]

Nice to know that the sound improved a bit.Also different speakers can sound different way.So may everyone not improve vast improvement.Whenever I test a device,I try to listen it with my ATH-M50 headphones.It picks up minor changes too which are easily missed in speaker systems due to many reasons.I am sure that in acoustically corrected room and flat sounding speaker system,one can make out the changes easily.Using 350ohm resister,bass can be improved,may be heavy.A simple way is that instead of 1K resistor in parellal to 440ohms,add another 1k in series (to 1k)and make so that 2K will be parallel with 440ohms.It will make total resistance of 362ohms.That will increase the bass,but may sound stage will shrink and also treble may not be better.Not tried yet though.

Rather parallel default 1K? with 560? which will give ~360? result, or 510? will give 338?. 560? and 510? are standard values easily available.

 

[sachu888]

Any Diyaudio members are using b1 with 330r or 390r resisters.

Regards
Sachin

 

[spirovious]

Rather parallel default 1K? with 560? which will give ~360? result, or 510? will give 338?. 560? and 510? are standard values easily available.

No, 1K resistor in series with existing 1K in the circuit.So total 2K parallel with 440ohm will give 362ohms.Current mod is using 1K in parallel with 440ohms.

 

[spirovious]

Any Diyaudio members are using b1 with 330r or 490t resisters.

Regards
Sachin

I dont know really,I did some experiments and found this mod. In fact I got this mod in less than half an hour of testing.

 

[sachu888]

I dont know really,I did some experiments and found this mod.

I know Spiro,
Thanks for posting your findings. I never tried anything other than 1k in B1. I will try different values and post my findings.
BTW I have edited my previous post. It was 330r and 390r.

Regards
Sachin

 

[omishra]

No, 1K resistor in series with existing 1K in the circuit.So total 2K parallel with 440ohm will give 362ohms.Current mod is using 1K in parallel with 440ohms.

In the end final resistance value matters, whatever combinations you do. You are free to create resistance network to yield specific value.