Tracing The PeeCeeBee

[shaan]

Thought I'd share some pics of the latest design that's playing now.

 

[avesbilal]

Hello Everyone,

Today finally I was able to complete my V3 Amp which was long pending.

Originally I built this cabinet for a preamp however it didn't materialized, hence cabinet looks too crowded.

Here are some pictures.

http://i844.photobucket.com/albums/ab6/avesbilal/PeeCeeBee/IMG_20170705_174913_HDR_zpstwpcwhin.jpg

http://i844.photobucket.com/albums/ab6/avesbilal/PeeCeeBee/IMG_20170705_174004_HDR_zpst8jhisnc.jpg

http://i844.photobucket.com/albums/ab6/avesbilal/PeeCeeBee/IMG_20170705_174606_HDR_zps5u96r99x.jpg

http://i844.photobucket.com/albums/ab6/avesbilal/PeeCeeBee/IMG_20170705_174538_HDR_zpsmihgqgcb.jpg


Any suggestions/recommendation are welcome.

Thank you Shaan for the Amp kit.

Regards
Bilal

 

[shaan]

The cabinet looks superb! I love wooden cabs! You put some substantial work on it and the internal assembling! Kudos!

If you do not hear any hum from the speakers then let it be in the "packed" form. No space wasted!

Thanks for the update, I hope you will enjoy listening to PeeCeeBee V3.

 

[avesbilal]

The cabinet looks superb! I love wooden cabs! You put some substantial work on it and the internal assembling! Kudos!

If you do not hear any hum from the speakers then let it be in the "packed" form. No space wasted!

Thanks for the update, I hope you will enjoy listening to PeeCeeBee V3.

Yes, there is no hum at all, can't hear any hum even by placing ear near to speakers.

I have grounded from both power supply at a single point. I also have a question here, I also grounded the earth pin from the power socket also to same ground, is that fine? With my experience I think this should be fine.

It was very difficult to assemble all the boards into such a small cabinet, I had to fit and remove at least 4-5 times before final assembly.

I had to reset the bias as I think I screwed up the bias preset by you while adjusting the output DC offset.

Currently bias is set to around 11.7-11.9mva for respective channels and DC offset is around ~0.5 - ~0.6 mv respectively.

Regards
Bilal

 

[shaan]

Very nice!

Usually loop-breaker should be installed between the chassis and PSU ground but if connecting the amp to source/preamp causes no motorboating from the speaker then not necessary.

 

[avesbilal]

Very nice!

Usually loop-breaker should be installed between the chassis and PSU ground but if connecting the amp to source/preamp causes no motorboating from the speaker then not necessary.

I read somewhere that isolater circuit is required to ground two separate psu together to single chassis, but thought to try it without isolater circuit first. I don't know if isolater circuit will help me in anyway, if it would I will implement it. By the way I always power off everything before connecting amp to preamp/DAC. Once while I was testing the amp before compete assembly, i disconnected the source while the amp was ON and i heard a continuous noise from speakers (is that Moterboarting effect)

The cabinet is built with metal sheet, on which I used wooden face and back plate.

Regards
Bilal

 

[shaan]

Without proper shielding and/or open inputs stray-EMI/RFI can sometimes cause noise from speaker. This noise is similar to the sound amps generate when one touches the open input.

The motorboating effect caused by ground loop is a low-volume low-frequency "krrrrrr..." type noise with almost no high frequency information.

 

[MaSh]

Hello Everyone,

Today finally I was able to complete my V3 Amp which was long pending.

Originally I built this cabinet for a preamp however it didn't materialized, hence cabinet looks too crowded.

Here are some pictures.

Thank you Shaan for the Amp kit.

Regards
Bilal

Wow that looks fantastic.

 

[shaan]

A short review on how the V4 sounds in a basic set-up:

PeeCeeBee V4 GB

 

[Aniket]

PCB's look stunning bro.

Appreciate your work.

 

[SanjeevM]

Awesome work !

Sent from my ASUS_Z00AD using Tapatalk

 

[manniraj]

Here is my build of the V4

I would say one of the sweetest amplifier that I have heard so far. Effortless and very good sound stage. Couple of weeks back we heard it with Captain's XLS-Encore bookshelf made for a local member and surprised at how good the pairing was with respect to the bass, sweet mids and clear highs. It paired well with XLS compared to my Frugal horns . The cabinet is actually for Class A and I was using for Aleph J till sometime back but planning to use it for my upcoming Sony VFET2 amp build. Because of the size of the heat sinks I have cranked up the lateral mosfets bias to 500mV and planning to increase till 1V and see if there is actually any difference to the sound quality. As per Shaan's build guide the recommended bias is 110mV

Very easy and simple to build and right now powering with a 25-0-25 400VA power transformer paired with the Eight Audio PSU which as 40000uf caps (10000uf*4). Shaan helped me to debug some issues which I encountered because of my oversight for the NJW transistors especially over the mobile and sometimes on the mail

 

[shaan]

Hi Ramesh! Thanks for the review.

It is the first PeeCeeBee with a manual bias spreading trimmer for the purpose of fine-tuning the bias to suit one's taste or increasing the class-A output level. In fact one can lower the PSU voltage to +/-20V and increase the bias to 2A and have a pure class-A amplifier (with huge heatsinks of course). Good to see that you are experimenting with it. Looking forward to your report on how frugal horns sound with 1A biased V4. :cheers:

 

[Aniket]

Is there a version with BJT output devices ?

 

[shaan]

Is there a version with BJT output devices ?

Nope.

I think manniraj meant the MOSFETs by mentioning "NJW transistors".

 

[Aniket]

Nope.

I think manniraj meant the MOSFETs by mentioning "NJW transistors".

any plans for designing one ?

 

[shaan]

any plans for designing one ?

A subwoofer amplifier yes. However, a BJT output amplifier will not be a PeeCeeBee.

 

[Aniket]

A subwoofer amplifier yes. However, a BJT output amplifier will not be a PeeCeeBee.

BTW, what is a PeeCeeBee ?
perhaps i got your point here. this amp is not suited for BJT outputs.
according to the datasheets Lateral FETs have much higher input and output capacitance, specially P-channel compared to BJT's,
and Lat FETs require much more idle current comparatively for similar THD performance.

Regards,
Aniket

 

[captrajesh]

I would say one of the sweetest amplifier that I have heard so far. Effortless and very good sound stage. Couple of weeks back we heard it with Captain's XLS-Encore bookshelf made for a local member and surprised at how good the pairing was with respect to the bass, sweet mids and clear highs. It paired well with XLS compared to my Frugal horns.

Just saw the post. My GRR speaker build is over, finally. I was driving past Bangalore on my way from Trivandrum to my new place Kurnool and thought of hand delivering the X-LS & X-LS to forum member Sethu_nr who had requested me to help him out with the build. So, the speakers were in my Car's boot when I visited Manniraj, essentially to pick up the Ovation SX kit which I bought off him.

Coming to the point, I was skeptical of the DIY amp builders who used to document their design and builds on the forum.

We had FLAC files on his Laptop going through a Soekris DAC, BA-3, Peeceebee driving the Frugel Horns having Alpair 7.3P drivers. They were sounding nice but I thought the highs were a wee bit rolled off. I was wondering (probably stemming from my prejudice) how they would've sounded if driven by the SX. We then shifted to Continuums of Kartikey. Though highs were better, being small speakers, their limitation to reproduce the lows was clearly evident. They sounded marginally better when Kartikey played the source through his Mojo DAC bypassing the BA-3.

I wanted to see how the X-LS would sound in the same setting. We took out the pair from the boot, unpacked and plugged them in. I was completely taken by surprise at how good the setup sounded. The synergy of the whole chain was amazing. We played several tracks across the genre. All that came out was wonderfully balanced sound that was very pleasing to our ears. Kudos to Shaan for designing such a wonderful sounding amp.

 

[shaan]

BTW, what is a PeeCeeBee ?

This is PeeCeeBee- PeeCeeBee

perhaps i got your point here. this amp is not suited for BJT outputs.

I don't think that's true.

according to the datasheets Lateral FETs have much higher input and output capacitance, specially P-channel compared to BJT's, and Lat FETs require much more idle current comparatively for similar THD performance.

Respectfully disagree. There are multiple ways other than heatsinks to work around such a problem. As for example, PeeCeeBee V4 has 0.0005% 100Hz THD and 0.001% 1KHz THD with 30mA MOSFET bias i.e. deep into Class-AB.

Also, if output devices dictated THD then what on earth is GNFB doing in the damn circuit?