Don-Audio MEQ vs Analogvibes midrange eq chassis

[EugeneKei]

Hello gents.
I have a nice clone of dual PEQ and my next eq I want to try to build is a mid-range MEQ-5 clone. I found full kit on Don-Audio, and it looks good, I mean you can buy there almost all you need. But after I saw Analogvibes meq chassis I've fallen in love with it)
Do you have experience in building Don-Audio MEQ kit and Analogvibes meq chassis?
Which one has better structure (architecture) and which one sounds better?
My main concern that I'm more noob than experienced builder) From one side Don-Audio has pcb, list on components, and in general almost all you need to built a unit. From other hand Analogvibes midrange eq chassis looks great, and at the same time more complex as there is no pcb I believe and not sure if it's easy enough to find all details and their price.
Any pitfalls, advantages and disadvantages of both? and what would you suggest?
Thank you in advance

 

[JMan]

Hi Eugene,

As you said, Don Audio offers a pcb-based project. The AnalogVibes chassis is designed for a Point-To-Point (handwired) build. AV only sells the chassis, which comes with a wiring diagram and BOM, but you'll have to source parts yourself. I assume that for the Don Audio project, they sell many of the major components, or perhaps even a complete components kit (no doubt at a substantial mark-up, but you're paying for someone else to take the work out of it for you in that case).

I have built four units from AnalogVibes (two LA2As and two EQP-1As), and I find them to be very clear, fun to build, and in some ways easier than pcbs. I was going to write a whole long explanation clarifying why I think they are easier, but honestly it was too much text. Suffice it to say that P2P and pcbs each have their own pros and cons. P2P is probably going to represent more labor up front, and sourcing your own parts adds even more work to that, so I would suggest that you factor that into your decision.

I can't comment on the sound of either of these MEQs, except to say that the AnalogVibes will be a pretty straightforward recreation of the original unit, substituting a few modern parts where you find that certain out-of-production "vintage" stuff is unavailable or unreasonably priced (or simply doesn't matter to the end product). It won't be a "take" on the circuit, or a modified or "improved" version. Whether that means it's better, worse, or the same as Don Audio's (which might also be identical to the original circuit), I couldn't say. I'm sure they will both sound great. Hand-wired is more "authentic." Does this matter in the end? I don't know.

It would also be irresponsible not to mention that, since you say you're a "noob," tube projects are generally more hazardous than the average solid state build due to the high voltages involved, so be sure that you have some understanding of how to stay safe when working on these. That said, I am no rocket scientist (rather, I am a musician with a penchant for overcomplicated hobbies) and I have managed to build the tube projects I mentioned above without incident, paying close attention to good safety practices.

Okay, sorry that this post has become so long. To conclude, I guess I'll say that I personally would go the AnalogVibes route, with the understanding that the building process itself will be more labor. However, whichever you choose, I'm sure you will be happy with the end result. Good luck!

 

[soapfoot]

One really hard thing is the 2k5 reverse log pot.

I’ve got a fully built MEQ-5 in an A-V chassis but have not managed to source a through-hole pot for the mid dip.

I’ve been in contact with Blore-Edwards, but for whatever reason haven’t managed to get one shipped to me yet.

 

[JMan]

I got all excited when I saw 2k2 reverse log pots from audio maintenance thinking that it was the right value, but alas...

I'm planning to start a pair of MEQ-5s from AV sometime this upcoming year, so if you happen to get a line on some of those pots (i.e. if Blore Edwards gets back to you), please let me know! I'd be up for grabbing a couple as well. Maybe having more than one person interested in buying would help the cause.

Sorry to derail the thread!

 

[soapfoot]

2k2 just might be close enough for me—if you got one in the higher end of the tolerance range, it’d be nearly within 10%

 

[EugeneKei]

Hi Eugene,

As you said, Don Audio offers a pcb-based project. The AnalogVibes chassis is designed for a Point-To-Point (handwired) build. AV only sells the chassis, which comes with a wiring diagram and BOM, but you'll have to source parts yourself. I assume that for the Don Audio project, they sell many of the major components, or perhaps even a complete components kit (no doubt at a substantial mark-up, but you're paying for someone else to take the work out of it for you in that case).

I have built four units from AnalogVibes (two LA2As and two EQP-1As), and I find them to be very clear, fun to build, and in some ways easier than pcbs. I was going to write a whole long explanation clarifying why I think they are easier, but honestly it was too much text. Suffice it to say that P2P and pcbs each have their own pros and cons. P2P is probably going to represent more labor up front, and sourcing your own parts adds even more work to that, so I would suggest that you factor that into your decision.

I can't comment on the sound of either of these MEQs, except to say that the AnalogVibes will be a pretty straightforward recreation of the original unit, substituting a few modern parts where you find that certain out-of-production "vintage" stuff is unavailable or unreasonably priced (or simply doesn't matter to the end product). It won't be a "take" on the circuit, or a modified or "improved" version. Whether that means it's better, worse, or the same as Don Audio's (which might also be identical to the original circuit), I couldn't say. I'm sure they will both sound great. Hand-wired is more "authentic." Does this matter in the end? I don't know.

It would also be irresponsible not to mention that, since you say you're a "noob," tube projects are generally more hazardous than the average solid state build due to the high voltages involved, so be sure that you have some understanding of how to stay safe when working on these. That said, I am no rocket scientist (rather, I am a musician with a penchant for overcomplicated hobbies) and I have managed to build the tube projects I mentioned above without incident, paying close attention to good safety practices.

Okay, sorry that this post has become so long. To conclude, I guess I'll say that I personally would go the AnalogVibes route, with the understanding that the building process itself will be more labor. However, whichever you choose, I'm sure you will be happy with the end result. Good luck!

Thank you a lot. The most concerning with AV chassis are some details which I think would be hard to find or are pretty expensive(inductor, transformers) . But I got your point. Appreciate your reply)

 

[Script]

Do you really need a faithful reproduction ? Faithful electronically and in looks ?

Those AV panels do look nice. But do you need all the additional metalwork for transformers etc ? Pretty much looks like that's what the AV offer is, meaning you'd need all the right transformers etc etc etc. -- I see cost explosion...

Instead might go truly DIY and use schematics on Gyraf's page here:
https://www.gyraf.dk/gy_pd/pultec/pultec.htm
It's actually few, or a manageable number of, components -- and doesn't really need a PCB (breadboard fine to hold inductors). Wiring the rotaries, albeit easy, would be a bit time consuming though.

Just the inductor set can be had for comparatively cheap (if you can't or do not want to DIY, like me). Just the front panel can also be custom ordered for comparatively cheap (or do your own). Could skip all the expensive parts and go op amps. And a PSU for op amps is not too complicated, potentially lethal, or expensive.

If you do not want to design and build op amp stages from scratch, you could buy 'modules' and just hook them together. You'd need a line receiver, an output buffer (gain stage), and a line driver.

That way it won't be a faithful Pultec reproduction -- just an inductor filter DIY unit
___

Image shows an MEQ5 stereo unit that I housed in a 1U case, with extra filter frequencies and bandwidth for the mid cut. No tubes, no transformers, no B+ PSU -- instead all op amps -- and the faceplate is handmade with handwritten legend. Not too difficult to build and, above all, cost effective

 

[JMan]

Thank you a lot. The most concerning with AV chassis are some details which I think would be hard to find or are pretty expensive(inductor, transformers) . But I got your point. Appreciate your reply)

Of course!

Regarding those inductors and transformers…would you not still need those parts for the Don Audio version? In which case, you could — at the very least — buy those items from them, exactly as you would be doing if you went with their kit. I wonder how they solved some of those supply issues? After all, Don Audio is in fact the distributor for AnalogVibes (different companies, but all AV orders are actually fulfilled by Don Audio), and they have many hard-to-find bits that are used in those builds.

If the concern is that you “need” specific transformers in order to use the AV chassis (e.g., you must find a vintage transformer that hasn’t been made in half a century and only comes up on eBay for the price of a kidney), that’s not strictly true. AV offers the cutouts for vintage iron and adapter plates for Sowters, and it’s quite easy to find mounting solutions for a host of other readily available transformers, so you have lots of options. Similarly, you aren’t locked in to using the pricey can capacitor in the PSU (you can just use regular electrolytics mounted inside the chassis), and so on and so on. In other words, you have the option to go full vintage (and crazy expensive) if you so choose, but you definitely aren’t required to. Or, of course, just go with the Don Audio kit, which is no doubt also a good option.

The other way to go, of course, is as Script suggested — really DIY the thing. While I’m less familiar with the history of the MEQ, a quick look at the numerous incarnations of the EQP makes it quite clear that Pultec themselves have not been slavishly devoted to one single version of the circuit, so I’d say that customization and experimentation is in the spirit of these units.

 

[HerbertR]

I also have ordered nearly all parts for a pair MEQ-5. The Frontpanels should come from Franks the next days. Power Coated, in Pultec Blue Ral 5009. As for the 2K5 Revlog Pot I will use more common Dual 5K Revlog using both 5K gangs connected in parallel to get the half value. I bought Alpha Pots from Tayda. Should thoeretically work. I will also go with DONs MEQ5 PCBs and his EF Inductors. For the Gainstage I will use Gyrafs SRPP from the GPultec, classical equipped with Transformers Lundahls.

 

[EugeneKei]

I also have ordered nearly all parts for a pair MEQ-5. The Frontpanels should come from Franks the next days. Power Coated, in Pultec Blue Ral 5009. As for the 2K5 Revlog Pot I will use more common Dual 5K Revlog using both 5K gangs connected in parallel to get the half value. I bought Alpha Pots from Tayda. Should thoeretically work. I will also go with DONs MEQ5 PCBs and his EF Inductors. For the Gainstage I will use Gyrafs SRPP from the GPultec, classical equipped with Transformers Lundahls.

Hello. Do you know where to buy/order Gyrafs SRPP? I was surfing the internet and just found PEQ pcb +Gyrafs SRPP but no option just buy Gyrafs SRPP pcb

 

[HerbertR]

Hello. Do you know where to buy/order Gyrafs SRPP? I was surfing the internet and just found PEQ pcb +Gyrafs SRPP but no option just buy Gyrafs SRPP pcb

Hi, I think you can only buy them together and throw the two PEQ1 Filterboards into the wastepaper basket. You can also try to etch them yourself or do Gyrafs SRPP Circuit Mainboard with the 6.3V DC regulated Heatervoltage and the Lundahltransformerplacement PTP. It is an easy circuit.

 

[Lakewood]

Hello. Do you know where to buy/order Gyrafs SRPP? I was surfing the internet and just found PEQ pcb +Gyrafs SRPP but no option just buy Gyrafs SRPP pcb

I recently redesigned the SRPP PCB and the FILTER PCB of the Gyraf Pultec! I still have PCBs available! Just write me a PM

 

[Gustav]

I’ve been in contact with Blore-Edwards, but for whatever reason haven’t managed to get one shipped to me yet.

Any luck getting through? I found your post doing a search for BE to see if people were experiencing problems - because, I am.

Gustav

 

[soapfoot]

No luck yet.

I ordered a dual 5k RA that I’m going to gang together as a substitute in the meantime

 

[HerbertR]

I got the MEQ-5 Filterboards, the EF Inductors and the Lundahls In/Out TX for the SSRP today from Don's.
The MEQ-5 Filterboards look pretty nice. Very easy, excellent. I traced the components on the board and comparerd them to the Schematic from Gyraf.
There is one difference in the Low boost section. In the MEQ5 schematic the 500 Hz Low Boost show LC Filter 280mH+150nF - that gives a frequency of about 770Hz, thats wrong IMHO.
The Don's PCB Board say 280mH+470nF - that gives much more correct 450Hz for the 500Hz Low Boost Band.
Analog Vibes schematic shows also like in Gyrafs Schematic 280mH+150nF, that should not give the 500Hz Band. Or am I wrong?
Calculated with fc=1/(2pi✓(LC))

The only thing I am missing in the Dons MEQ-5 board design is the bypass. I will implement a "real" Relay Bypass board from SilentArts I ve laying around. With a small cheap StepUp Board I will convert Voltage from the 6.3V DC Rail from the SSRP Gpultec MakeUp Mainboards to 12 V for driving the two bypass 12V Relays.

 

[EugeneKei]

I got the MEQ-5 Filterboards, the EF Inductors and the Lundahls In/Out TX for the SSRP today from Don's.
The MEQ-5 Filterboards look pretty nice. Very easy, excellent. I traced the components on the board and comparerd them to the Schematic from Gyraf.
There is one difference in the Low boost section. In the MEQ5 schematic the 500 Hz Low Boost show LC Filter 280mH+150nF - that gives a frequency of about 770Hz, thats wrong IMHO.
The Don's PCB Board say 280mH+470nF - that gives much more correct 450Hz for the 500Hz Low Boost Band.
Analog Vibes schematic shows also like in Gyrafs Schematic 280mH+150nF, that should not give the 500Hz Band. Or am I wrong?
Calculated with fc=1/(2pi✓(LC))

The only thing I am missing in the Dons MEQ-5 board design is the bypass. I will implement a "real" Relay Bypass board from SilentArts I ve laying around. With a small cheap StepUp Board I will convert Voltage from the 10V Rail from the SSRP Gpultec MakeUp Mainboards to 12 V for driving the two bypass 12V Relays.

What is the Width and Height of pcb?

 

[HerbertR]

What is the Width and Height of pcb?

They are 16,5 x 10cm.

 

[HerbertR]

Merry Xmas, I want to share my progress with the Dons Audio MEQ5 Filterboards, the sexy powedercoated/UV printed Frontpanel from Franks frontpanels.de (Frank you are the best), Adam Hall 19" 2HE Case, the used SSRP Gainstage from Gyrafs (respect) GPultec PCBs Kit equipped with Lundahl Audio TX, and Sedlbauer 30VA Power Transformers (TX1 220V->12V and TX2 15V->220V)
I get after the Bride Rectifier for the B+/HT Anode-Voltage about 242V DC loaded with Tube (my used 6N23P Sovtec draws about 5mA). The Voltage drops about 5 Volt down after my used 1K R2 to about 237 Volts. I really recommend to mount especially the LM317 for the 6.3VDC rail directly on the Case. It will get really, really warm and to avoid a thermal shoutdown you should do this. For driving the real Bypass Relays I am using SilentArts PCBs. They are holding directly the In/Out XLRs Jacks. I ve taped the 6.3V DC heater rail and convert this voltage useing cheap step down/up boards for driving Lamps and Relays. Easy...

 

[HerbertR]

These are the fully populated Filterboards from DONs. I am using Dons EF Inductors. They should show a little bit more color compared to optional possible RM Inductors as they should tend earlier to saturate. But I am definitily not a Inductor nor a Transformer specialist. Correct me if I am Wrong. Cool to have two options...

 

[HerbertR]

First test of my builds show a lot of necessity of optimization.
-my ordered Inductors from Dons are particulary far away from the needed values and I got no response of Don. So I recalculated/matched the LC Filtercircuits and adopted the Caps for correct Frequecies, perfectly now...
-too much hum actually for my taste, I will replace all rotaryswitch-cables and potentiometer-cables with new ordered shielded ones.The unshieled ones are super sensitive and collect exensivly nearly all like hum. If these action is to less I will additionally transfer all Transformers into a external box. This piece is worth really every effort......
-Does anyone has an idea to increase the passive loss makeup Gain about 2.5dB to get unity gain on the SSRP circuit? Negative feedback, how to do?

And btw - this EQ sounds "overkill". Never heard any better EQ on A/E Guitars. On the point, always good.... Honestly, throw your MEQ5 plugins in the waste paper basket. These plugs do only a static homeopathic dose....This outboard is a total other league ....