Quadzilla
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Amp Guts Photos - Official Thread - Lets see those pics
- Thread starter svtb15
- Start date
Quadzilla
Supporting Member
Quadzilla
Supporting Member
Demeter HBP1J-800D to be more specific (the "J" denotes the Jensen transformer DI option)... ;-)
Actually - might that be classified as the HBP1J-800D? Looking closer, I think I see the Jansen there in the back left corner...
was doing some tube rolling in my Demeter VTBP-M-800DJ and decided I might as well post some gut shots of it while I was at it.
FWIW, I ended up replacing the stock V1 EH 12AX7 with a Sovtek 12AX7LPS, and the stock V2 JJ EC81/12AT7 with a NOS Jan Phillips 12AT7WC.
The Sovtek in V1 did not do a great deal to the over all tone, other than having much less hiss than the EH 12AX7.
The Jan Phillips in V2 did something very nice to my ears. Hard to put it words, but it would seem to have made an already impressively responsive amp even more so .. more responsive to the touch on each string. IDK, my ears are not great anymore, but I did hear something change for the better - and it was already pretty great to begin with
New tubes - top view.
View attachment 982494
Real gut shot
View attachment 982495
enjoy!
Is it just me or is the workmanship of the Demeter stuff, uh, not great for high dollar gear? Both of these look prototype-ish to me with parts and jumpers barnacled onto the PCBs. Definitely not at the same level as say the Darkglass or Arkham pieces posted in this thread.
I’ve always thought that. The boards and packaging are not up to the professional standards that you see today in comparatively priced products.
Quadzilla
Supporting Member
While I agree that the board layout is a bit unusual I also like the fact that the components are spread out from each other which may in itself, may provide some level of isolation from electronic noise from one part to another.
Bass Player Magazine doesn’t seem to think so:
“CALIFORNIA AMP AND STUDIO GEAR GURU JAMES Demeter has been a major force in the biz for over 35 years, with many of his designs achieving industry-standard status in studios across the world.”
“The Demeter Minnie head is exceptionally well built and handsome, with a refreshingly no-nonsense front-panel that’s as grokable as they come. The box is covered in vinyl and blessed with a durable top-mounted handle and sizable rubber feet. It’s not as portable as some Class D amps, but its small footprint and low weight still make it a cinch to schlep. Removing the amp from its box revealed a interestingly anachronistic internal design, with the old-school PCB of the preamp standing in stark visual contrast to the thoroughly contemporary surface-mounted board of the Class D/SMPS amp module. The two dual triodes are well protected when in the box, but I’m not a big fan of the blue LEDs that illuminate them from below when the amp is powered up. Seems a little cheesy, although this subjective opinion is certainly not shared by many high-end amp audiophile amp designers. The preamp features good components, like metal-film resistors and Wima capacitors. Tube nuts will approve.”
Quotes from Bass Player Magazine’s review of the Demeter VTBP-M-800D head linked below.
Besides, no other amp sounds like a Demeter, especially in a mix!
Invalid Link Removed
Quadzilla
Supporting Member
And there you have it..... It's not cramped, with components practically stacked on-top of each other like many newer designs. It's just more old-school, which works for me...
Agreed. I have been waffling about commenting on it for a while but one of their mic preamps made it onto my bench the other day and it's really poorly laid out inside with traces cut and components barnacled on to the PCB and cables and wire going every which way. It does sound wonderful and all of the Demeter stuff I've used does but I have to say the internal workmanship is marginal.
Nah, not if the board designer knows what they are doing. Though my beef is not the layout so much as the way it's assembled. The cap stuck off the switch for example.
Bass Player also thought the Accuswitch was an awesome feature.
Again, I actually quite like Demeter stuff sonically and I really dug the HBP1-800D I tried at Bass Central a while back. I was a bit taken aback at the internal build quality and would have expected better. Oh well, if it works it works. Carry on.
For contrast, this is an old school design and it is beautifully built:
Hi DIYers
You asked for a pic so here is my upgrade to my personal Peavey MKIV 300W Bass Amp made in 1980. Has really good functionality with two independent switchable channels. The mod you can see is to the power supply, where the original 5,000 uF filter caps in each of + and - rails were increased to 100,000 uF each rail (10 x 10,000 uF). This set of caps is in series with the speaker so directly affects the sound. The LV supply was also increased from 1,000 uF to 22,000 uF in each rail. Also modified some of the coupling capacitors and EQ caps to improve bottom end. Numeric power output remains unchanged but the amp delivers better sustain and better LF performance. Did not cost much to do. The amp has been like this for more than ten years and has never missed a beat with regular use. Thank you Peavey for a great starting point.
Why did I do this ? To find out if it would work and what benefit would result - and because it is my amp and I can. The 200,000 uF is an overkill.
44,000 uF as used to upgrade my Peavey XRD680 2 x 150W mixer amp would have been adequate, but had the room in the MKIV so why not ?
Computer bus caps are way better than the domestic quality caps I used but were too large to fit into the space available - so compromise played a role.
With a pair of 18 inch Eminence drivers this amp delivers wall shaking bass with ease.
I have installed similar mods to my other higher powered Class AB rack amps as and where space permits. The more modern amps have larger caps anyway as standard so in many cases they are adequate as-is. They also run at much higher voltages - ie more than 100 VDC - so suitable large value caps are hard to find
You asked for a pic so here is my upgrade to my personal Peavey MKIV 300W Bass Amp made in 1980. Has really good functionality with two independent switchable channels. The mod you can see is to the power supply, where the original 5,000 uF filter caps in each of + and - rails were increased to 100,000 uF each rail (10 x 10,000 uF). This set of caps is in series with the speaker so directly affects the sound. The LV supply was also increased from 1,000 uF to 22,000 uF in each rail. Also modified some of the coupling capacitors and EQ caps to improve bottom end. Numeric power output remains unchanged but the amp delivers better sustain and better LF performance. Did not cost much to do. The amp has been like this for more than ten years and has never missed a beat with regular use. Thank you Peavey for a great starting point.
Why did I do this ? To find out if it would work and what benefit would result - and because it is my amp and I can. The 200,000 uF is an overkill.
44,000 uF as used to upgrade my Peavey XRD680 2 x 150W mixer amp would have been adequate, but had the room in the MKIV so why not ?
Computer bus caps are way better than the domestic quality caps I used but were too large to fit into the space available - so compromise played a role.
With a pair of 18 inch Eminence drivers this amp delivers wall shaking bass with ease.
I have installed similar mods to my other higher powered Class AB rack amps as and where space permits. The more modern amps have larger caps anyway as standard so in many cases they are adequate as-is. They also run at much higher voltages - ie more than 100 VDC - so suitable large value caps are hard to find
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