Post by jml77 on Dec 27, 2019 19:52:38 GMT
My son gave me this amp which he had rescued from being dumped in a skip. it was rather mouldy as it had been kept in damp basement flat.
He had no idea if it worked or not, but was surprised to see it had a Celestion Seventy 80 speaker, which was in reasonable condition despite the damp.
Well, it works. A few of the pots are a little crackly.
Channel 1 has Gain, Voice, Bass, Treble and Volume controls. Channel 2 has a switchable gain control, followed by TMB and Volume. Global Reverb, an 'Insert' 1/4 inch TRS jack and a 1/4 inch TRS footswitch jack socket. I've not tested these, and unsure of how they are configured.
The ch1 voice control seems to go from a mid notched sound, probably more fender like to a rather dull mid focused sound at the far end of the dial. The gain stays fairly clean until 4-ish on the dial (***see edited note 1), then it begins to clip. I'm not sure what the clipping circuit is but it maybe reverse series zener diodes, possibly a hard clipping circuit with high threshold, not sure yet as I've not traced the circuit out or tested by following the signal, only a visual inspection.
Channel 2 has a switchable gain control, and it looks as if the clipping is produced by a reverse parallel diode network, 2 in each leg. The typical 1n4148 diodes, whcih maybe in an opamp feedback loop giving tight yet soft low threshold clipping. TMB eq and channel volume follows. The gain sounds best to my ears by cutting the treble and bass and boosting the mids, a little tube screamer like with these settings.
It uses several channel switching dual opamps, JRC2120D, these help to produce a fairly uncluttered PCB. A few TL072 opamps, 1 at the input and for the reverb controls and tank driver.
The power amp is integrated IC, TDA7294v, having DMOS output buffers hence giving the amp the name 'Mosfet Lead' . Not sure how this is configured, could be anywhere between 40 - 80 watts depending on load and supply voltage. Some reviews suggect it is 40W @ 8 ohm and 65W @ 4 ohm, which differs from the later versions of the HB-80R
It has an R-core mains transformer, and it is very quiet in use, not much mains HUM or high gain hiss can be heard even with all controls at max.
The PCB is stamped with the code TEC80G and a google search reveals that the same amp is rebranded in various guises. Danville TEC80G and Tecamp TEC80G. Exactly the same except different brand names and odd cosmetic changes to the dial indicator transfers.
I thought the reverb was likely to be digital, but surprised to find a spring reverb tank inside the chassis. It is rather small though (8inch max) , unbranded and goes from barely on to extreme splash very quickly.
There are a few puzzles to solve, notably the 1/4 inch jack sockets on the front panel. (***Note 2) The rear panel has an external speaker socket and a line out 1/4 inch socket. from looking inside it would appear that the line out is taken from the speaker out via a potential divider network.
I'm not sure if it's worth contacting Thomann to see if they have a pdf manual. Somehow I doubt it after 12 years and further versions in production, but might be worth trying.
If anyone has such a manual I would be very grateful to get a copy. I have copies of the later versions, they have some similarities in layout and function but also some differences as far as I can tell.
I'm quite impressed with the sound, as long as it's kept fairly clean, the overdrive sounds can be very harsh. It can be a very bright amp particularly at low master volume levels, and the treble controls can make it rather ice-picky, but dialling them down and tweaking the bass and mids gives quite a warm tone with plenty of punch.
If the new ones are similar to this 2007 version then they are good value at such a low cost.
(Edit Note1: On checking this the overdrive/distortion starts at just a little over 1 on the gain control. There is no other preamp control on channel 1 so this is mostly a distortion channel, having said that there's quite a bit of clean preamp gain/volume between 0 and 1.)
(Edit Note2: I'm fairly sure that the Insert socket on the front panel, is configured for a line out send on the ring, Return on the tip. I'll need to mangle up a lead to check this out with effects pedals some time in the near future)
He had no idea if it worked or not, but was surprised to see it had a Celestion Seventy 80 speaker, which was in reasonable condition despite the damp.
Well, it works. A few of the pots are a little crackly.
Channel 1 has Gain, Voice, Bass, Treble and Volume controls. Channel 2 has a switchable gain control, followed by TMB and Volume. Global Reverb, an 'Insert' 1/4 inch TRS jack and a 1/4 inch TRS footswitch jack socket. I've not tested these, and unsure of how they are configured.
The ch1 voice control seems to go from a mid notched sound, probably more fender like to a rather dull mid focused sound at the far end of the dial. The gain stays fairly clean until 4-ish on the dial (***see edited note 1), then it begins to clip. I'm not sure what the clipping circuit is but it maybe reverse series zener diodes, possibly a hard clipping circuit with high threshold, not sure yet as I've not traced the circuit out or tested by following the signal, only a visual inspection.
Channel 2 has a switchable gain control, and it looks as if the clipping is produced by a reverse parallel diode network, 2 in each leg. The typical 1n4148 diodes, whcih maybe in an opamp feedback loop giving tight yet soft low threshold clipping. TMB eq and channel volume follows. The gain sounds best to my ears by cutting the treble and bass and boosting the mids, a little tube screamer like with these settings.
It uses several channel switching dual opamps, JRC2120D, these help to produce a fairly uncluttered PCB. A few TL072 opamps, 1 at the input and for the reverb controls and tank driver.
The power amp is integrated IC, TDA7294v, having DMOS output buffers hence giving the amp the name 'Mosfet Lead' . Not sure how this is configured, could be anywhere between 40 - 80 watts depending on load and supply voltage. Some reviews suggect it is 40W @ 8 ohm and 65W @ 4 ohm, which differs from the later versions of the HB-80R
It has an R-core mains transformer, and it is very quiet in use, not much mains HUM or high gain hiss can be heard even with all controls at max.
The PCB is stamped with the code TEC80G and a google search reveals that the same amp is rebranded in various guises. Danville TEC80G and Tecamp TEC80G. Exactly the same except different brand names and odd cosmetic changes to the dial indicator transfers.
I thought the reverb was likely to be digital, but surprised to find a spring reverb tank inside the chassis. It is rather small though (8inch max) , unbranded and goes from barely on to extreme splash very quickly.
There are a few puzzles to solve, notably the 1/4 inch jack sockets on the front panel. (***Note 2) The rear panel has an external speaker socket and a line out 1/4 inch socket. from looking inside it would appear that the line out is taken from the speaker out via a potential divider network.
I'm not sure if it's worth contacting Thomann to see if they have a pdf manual. Somehow I doubt it after 12 years and further versions in production, but might be worth trying.
If anyone has such a manual I would be very grateful to get a copy. I have copies of the later versions, they have some similarities in layout and function but also some differences as far as I can tell.
I'm quite impressed with the sound, as long as it's kept fairly clean, the overdrive sounds can be very harsh. It can be a very bright amp particularly at low master volume levels, and the treble controls can make it rather ice-picky, but dialling them down and tweaking the bass and mids gives quite a warm tone with plenty of punch.
If the new ones are similar to this 2007 version then they are good value at such a low cost.
(Edit Note1: On checking this the overdrive/distortion starts at just a little over 1 on the gain control. There is no other preamp control on channel 1 so this is mostly a distortion channel, having said that there's quite a bit of clean preamp gain/volume between 0 and 1.)
(Edit Note2: I'm fairly sure that the Insert socket on the front panel, is configured for a line out send on the ring, Return on the tip. I'll need to mangle up a lead to check this out with effects pedals some time in the near future)